Previous simulation models have found positive effects of cognitive diversity on group performance, but have not explored effects of diversity in demographics (e.g., gender, ethnicity). In this paper, we present an agent-based model that captures two empirically supported hypotheses about how demographic diversity can improve group performance. The results of our simulations suggest that, even when social identities are not associated with distinctive task-related cognitive resources, demographic diversity can, in certain circumstances, benefit collective performance by counteracting two types of conformity (...) that can arise in homogeneous groups: those relating to group-based trust and those connected to normative expectations towards in-groups. (shrink)

Debates in feminist political philosophy often focus on what problematic(s) to use in order to understand normative ideals, gendered differences, and their histories. For the purposes of this chapter, I will contrast two important problematics in these debates, the procedural/deliberative politics in the tradition of Critical Theory, represented here by Seyla Benhabib, and the poststructuralist or postmodern politics, represented here by Judith Butler. The goal of the contrast will be to set up the contribution that Gadamer’s work can make to (...) contemporary feminist philosophy. (shrink)

Abstract: There has been an ongoing dispute between defenders of world disclosure (understood here in a loosely Heideggerian sense) and advocates of normative debate. I will take up a recent confrontation between Charles Taylor and Robert Brandom over this question as my point of departure for showing how world disclosure can expand the range of normative argument. I begin by distinguishing pre-reflective disclosure—the already interpreted, structured world in which we find ourselves—from reflective disclosure—the discrete intervention of a particular utterance or (...) text. I discuss Taylor’s notion of social imaginaries as a way of thematizing our pre-reflective background and Talal Asad’s critique of Taylor to show how this background can be one space of argument. I then develop my own understanding of reflective disclosure, of which Taylor gives an indequate account, developing my argument with help of literature, including a close analysis of Susan Glaspell short story “A Jury of Her Peers.” This story illustrates how world disclosure can make normative arguments without confining itself to Brandom’s or Habermas’s idea of the exchange of reasons. (shrink)

The main aim of this book is to introduce the topic of limited awareness, and changes in awareness, to those interested in the philosophy of decision-making and uncertain reasoning.

The Bayesian maxim for rational learning could be described as conservative change from one probabilistic belief or credence function to another in response to newinformation. Roughly: ‘Hold fixed any credences that are not directly affected by the learning experience.’ This is precisely articulated for the case when we learn that some proposition that we had previously entertained is indeed true (the rule of conditionalisation). But can this conservative-change maxim be extended to revising one’s credences in response to entertaining propositions or (...) concepts of which one was previously unaware? The economists Karni and Vierø (2013, 2015) make a proposal in this spirit. Philosophers have adopted effectively the same rule: revision in response to growing awareness should not affect the relative probabilities of propositions in one’s ‘old’ epistemic state. The rule is compelling, but only under the assumptions that its advocates introduce. It is not a general requirement of rationality, or so we argue. We provide informal counterexamples. And we show that, when awareness grows, the boundary between one’s ‘old’ and ‘new’ epistemic commitments is blurred. Accordingly, there is no general notion of conservative change in this setting. (shrink)

In this paper, we develop a novel response to counterfactual scepticism, the thesis that most ordinary counterfactual claims are false. In the process we aim to shed light on the relationship between debates in the philosophy of science and debates concerning the semantics and pragmatics of counterfactuals. We argue that science is concerned with many domains of inquiry, each with its own characteristic entities and regularities; moreover, statements of scientific law often include an implicit ceteris paribus clause that restricts the (...) scope of the associated regularity to circumstances that are ‘fitting’ to the domain in question. This observation reveals a way of responding to scepticism while, at the same time, doing justice both to the role of counterfactuals in science and to the complexities inherent in ordinary counterfactual discourse and reasoning. (shrink)

In the biomedical context, policy makers face a large amount of potentially discordant evidence from different sources. This prompts the question of how this evidence should be aggregated in the interests of best-informed policy recommendations. The starting point of our discussion is Hunter and Williams’ recent work on an automated aggregation method for medical evidence. Our negative claim is that it is far from clear what the relevant criteria for evaluating an evidence aggregator of this sort are. What is the (...) appropriate balance between explicitly coded algorithms and implicit reasoning involved, for instance, in the packaging of input evidence? In short: What is the optimal degree of ‘automation’? On the positive side: We propose the ability to perform an adequate robustness analysis as the focal criterion, primarily because it directs efforts to what is most important, namely, the structure of the algorithm and the appropriate extent of automation. Moreover, where there are resource constraints on the aggregation process, one must also consider what balance between volume of evidence and accuracy in the treatment of individual evidence best facilitates inference. There is no prerogative to aggregate the total evidence available if this would in fact reduce overall accuracy. (shrink)

We argue that concerns about double-counting—using the same evidence both to calibrate or tune climate models and also to confirm or verify that the models are adequate—deserve more careful scrutiny in climate modelling circles. It is widely held that double-counting is bad and that separate data must be used for calibration and confirmation. We show that this is far from obviously true, and that climate scientists may be confusing their targets. Our analysis turns on a Bayesian/relative-likelihood approach to incremental confirmation. (...) According to this approach, double-counting is entirely proper. We go on to discuss plausible difficulties with calibrating climate models, and we distinguish more and less ambitious notions of confirmation. Strong claims of confirmation may not, in many cases, be warranted, but it would be a mistake to regard double-counting as the culprit. 1 Introduction2 Remarks about Models and Adequacy-for-Purpose3 Evidence for Calibration Can Also Yield Comparative Confirmation3.1 Double-counting I3.2 Double-counting II4 Climate Science Examples: Comparative Confirmation in Practice4.1 Confirmation due to better and worse best fits4.2 Confirmation due to more and less plausible forcings values5 Old Evidence6 Doubts about the Relevance of Past Data7 Non-comparative Confirmation and Catch-Alls8 Climate Science Example: Non-comparative Confirmation and Catch-Alls in Practice9 Concluding Remarks. (shrink)

The Repugnant Conclusion served an important purpose in catalyzing and inspiring the pioneering stage of population ethics research. We believe, however, that the Repugnant Conclusion now receives too much focus. Avoiding the Repugnant Conclusion should no longer be the central goal driving population ethics research, despite its importance to the fundamental accomplishments of the existing literature.

Highlights: -/- • -/- Proposes forward-looking approach to studying climate collapse risks. • -/- Suggests diminishing returns on climate adaptation as a collapse mechanism. • -/- Suggests strategies for sustainable adaptation pathways in face of climate change. • -/- Illustrates analysis with examples of small island states and global food security. -/- Abstract: -/- This article proposes a forward-looking approach to studying societal collapse risks related to climate change. Such an approach should indicate how to study emerging collapse risks and (...) suggest strategies for adapting to them. Our approach is based on three postulates that facilitate a forward-looking approach: (1) collapse, if it occurred, would be a lengthy process rather than an abrupt event; (2) significant collapse risks already exist in some places; and (3) diminishing returns on adaptation to intensifying climate impacts are a key driver of collapse risks. The first two postulates suggests that collapse risks can be studied in process, while the third points to strategies for adaptation pathways that avoid unsustainable diminishing returns. Applying diminishing returns to climate change adaptation, rather than sociopolitical complexity or resource extraction, is also a novel theoretical contribution to collapse literature. [Open access]. (shrink)

In this article, we claim that recent developments in climate science and renewable energy should prompt a reframing of debates surrounding climate change mitigation. Taken together, we argue that these developments suggest (1) global climate collapse in this century is a non-negligible risk, (2) mitigation offers substantial benefits to current generations, and (3) mitigation by some can generate social tipping dynamics that could ultimately make renewables cheaper than fossil fuels. We explain how these claims undermine familiar framings of climate change, (...) wherein mitigation is understood as self-sacrifice that individuals and governments must be morally persuaded or incentivized to undertake. [Open access]. (shrink)

This article argues that common intuitions regarding (a) the specialness of ‘use-novel’ data for confirmation and (b) that this specialness implies the ‘no-double-counting rule’, which says that data used in ‘constructing’ (calibrating) a model cannot also play a role in confirming the model’s predictions, are too crude. The intuitions in question are pertinent in all the sciences, but we appeal to a climate science case study to illustrate what is at stake. Our strategy is to analyse the intuitive claims in (...) light of prominent accounts of confirmation of model predictions. We show that on the Bayesian account of confirmation, and also on the standard classical hypothesis-testing account, claims (a) and (b) are not generally true; but for some select cases, it is possible to distinguish data used for calibration from use-novel data, where only the latter confirm. The more specialized classical model-selection methods, on the other hand, uphold a nuanced version of claim (a), but this comes apart from (b), which must be rejected in favour of a more refined account of the relationship between calibration and confirmation. Thus, depending on the framework of confirmation, either the scope or the simplicity of the intuitive position must be revised. (shrink)

This appears in a supplementary issue of the Bulletin of the Institute of Classical Studies, entitled "Ancient Approaches to Plato's Timaeus.".

Although the treatise presented here is most interesting, it was never widely disseminated. As far as we know, it is preserved only in Latin, in one manuscript. The text poses many questions. Who produced a copy of the text? Who is the translator? Is the treatise a genuine work of Averroes? And if so, what was his intention in writing this monograph on the First Cause?

Laurie Paul argues that, when it comes to many of your most significant life-changing decisions, the principles of rational choice are silent. That is because, in these cases, you anticipate that one of your choice options would yield a transformative experience. We argue that such decisions are best seen as ones in which you anticipate awareness growth. You do not merely lack knowledge about which possible outcome will arise from a transformative option; you lack knowledge about what are the possible (...) outcomes. We show how principles of rational choice can be extended to cases of anticipated awareness growth. (shrink)

In engineering, as in other scientific fields, researchers seek to confirm their models with real-world data. It is common practice to assess models in terms of the distance between the model outputs and the corresponding experimental observations. An important question that arises is whether the model should then be ‘tuned’, in the sense of estimating the values of free parameters to get a better fit with the data, and furthermore whether the tuned model can be confirmed with the same data (...) used to tune it. This dual use of data is often disparagingly referred to as ‘double-counting’. Here, we analyse these issues, with reference to selected research articles in engineering. Our example studies illustrate more and less controversial practices of model tuning and double-counting, both of which, we argue, can be shown to be legitimate within a Bayesian framework. The question nonetheless remains as to whether the implied scientific assumptions in each case are apt from the engineering point of view. (shrink)

The expression of fragility has always been a difficult and complex matter for African Americans, for the discourse of mainstream media is set up to sustain their fragility while at the same time misrecognizing it. Even though the black public sphere split off from the dominant public sphere after the Civil War to enable distinctive forms of expression, the “practiced habits” of which Coates speaks continued in the structures of the dominant discourse. My essay will analyze the structure of America’s (...) indifference to fragility in three parts. In the first section, I will introduce a normative problematic that can track how the hegemonic public sphere uses the rhetoric of formal equality to subordinate and silence African Americans speech while it also opens a space for black speech to be heard rather than dismissed. I then will trace the silencing structures back to the Brown v. Board of Education Supreme Court decision of 1954, for this “progressive” decision provided a template for what can be said and cannot be said. The next second section examines how Ralph Ellison thematizes and revises the encounter between the black and dominant public spheres. In the last section of the essay, I analyze the ways that Ta-Nehisi Coates exposes the contemporary forms of these discursive structures. (shrink)

Debates in feminist political philosophy often focus on what problematic(s) to use in order to understand normative ideals, gendered differences, and their histories. For the purposes of this chapter, I will contrast two important problematics in these debates, the procedural/deliberative politics in the tradition of Critical Theory, represented here by Seyla Benhabib, and the poststructuralist or postmodern politics, represented here by Judith Butler. The goal of the contrast will be to set up the contribution that Gadamer’s work can make to (...) contemporary feminist philosophy. (shrink)

When speaking of the philosophical importance of James’s late style, critics and philosophers have taken two broad approaches. One route, exemplified by Martha Nussbaum, attributes this style to the sensitivity of the characters. The other, exemplified by Robert Pippin, attributes the writing’s complexity to the ambiguities of the moral codes during this period of history. In my reading, James’s texts address a more general problem of modernity, which is the flattening of the lifeworld (Lebenswelt) by disengaged approaches to both epistemology (...) and morality, the reduction of the lifeworld to the environment (Umwelt). James’s works open an ontological dimension to the question of language and normativity, a question that modernity’s moral languages—whether based on deontology, utility, or virtue—fail to articulate. His texts interrogate what normativity is rather than just portraying the sensitivity of the characters or uncertainty of the historical moment, although both of those readings are certainly justified. (shrink)

This book addresses a central dilemma in critical theory today: how to theorize the subject as both a construct of oppressive discourse and as a dialogical agent. By engaging a wide range of leading philosophical and critical thinkers—James, Habermas, MacIntyre, Rorty, Taylor, Derrida and West are all critiqued—Meili Steele proposes linking language with human agency in order to develop an alternative textual and ethical theory of the subject. Developing this theory through readings that address issues of identity politics, race and (...) feminist theory, Steele argues that we do not have to choose between an idealized or demonized modernity, offering new ways of understanding the ethical and political dimensions of imaginative narratives. (shrink)

While there is an extensive literature on how the precautionary principle should be interpreted and when precautions should be taken, relatively little discussion exists about the fair distribution of costs of taking precautions. We address this issue by proposing a general framework for deciding how costs of precautions should be shared, which consists of a series of default principles that are triggered according to desert, rights, and ability to pay. The framework is developed with close attention to the pragmatics of (...) how distributions will affect actual behaviours. It is intended to help decision-makers think more systematically about distributional consequences of taking precautionary measures, thereby to improve decision-making. Two case studies—one about a ban on turtle fishing in Costa Rica, and one about a deep-sea mining project in Papua New Guinea—are given to show how the framework can be applied. (shrink)

Olympe de Gouges is known primarily for La Déclaration des droits de la femme et de la citoyenne (1791), which is her response to the Declaration of the Rights of Man, adopted in 1789 by the National Assembly. Carol Sherman's book, Reading Olympe de Gouges, turns our attention away from normative principles of La Déclaration and directs it toward the ways that de Gouges's other texts challenge the normativity of the dominant social imaginaries of the time. Sherman’s book is required (...) reading for anyone wanting to participate in the debates about whether de Gouges deserves a place the Panthéon, but also in broader discussions about the history of feminism and the French Revolution. (shrink)

We address Steel’s Programme to identify a ‘preferred’ universe of set theory and the best axioms extending ZFC by using his multiverse axioms MV and the ‘core hypothesis’. In the first part, we examine the evidential framework for MV, in particular the use of large cardinals and of ‘worlds’ obtained through forcing to ‘represent’ alternative extensions of ZFC. In the second part, we address the existence and the possible features of the core of MV_T (where T is ZFC+Large Cardinals). In (...) the last part, we discuss the hypothesis that the core is Ultimate-L, and examine whether and how, based on this fact, the Core Universist can justify V=Ultimate-L as the best (and ultimate) extension of ZFC. To this end, we take into account several strategies, and assess their prospects in the light of MV’s evidential framework. (shrink)

Le problème de l’induction (humien) a récemment été abordé par Steel dans son article de 2010. Celui-ci soutient que les théories d’apprentissage formelles permettent de justifier logiquement le principe de l’induction, ce dernier assurant la fiabilité logique des méthodes. Cette proposition a été critiquée par Howson en 2011, ce dernier mettant en doute la possibilité même qu’une méthode puisse être logiquement fiable. Bien que Steel ait offert une réponse à cette critique, il n’y répond pas directement. Dans le présent article, (...) une réponse frontale à celle-ci est offerte en s’inspirant des pratiques de tests d’hypothèses en sciences biologiques. Pour ce faire, une règle de construction des ensembles d’hypothèses est proposée, règle offrant une justification logique au fait qu’une méthode convergera nécessairement vers la vérité. Cet amendement étant cohérent avec l’ensemble de la proposition de Steel, il est ainsi possible d’affirmer que sa thèse est renforcée par cette proposition. (shrink)

Floridi and Taddeo propose a condition of “zero semantic commitment” for solutions to the grounding problem, and a solution to it. I argue briefly that their condition cannot be fulfilled, not even by their own solution. After a look at Luc Steels' very different competing suggestion, I suggest that we need to re-think what the problem is and what role the ‘goals’ in a system play in formulating the problem. On the basis of a proper understanding of computing, I (...) come to the conclusion that the only sensible ground-ing problem is how we can explain and re-produce the behavioral ability and function of meaning in artificial computational agents. (shrink)

The view that phenomenally conscious robots are on the horizon often rests on a certain philosophical view about consciousness, one we call “nomological behaviorism.” The view entails that, as a matter of nomological necessity, if a robot had exactly the same patterns of dispositions to peripheral behavior as a phenomenally conscious being, then the robot would be phenomenally conscious; indeed it would have all and only the states of phenomenal consciousness that the phenomenally conscious being in question has. We experimentally (...) investigate whether the folk think that certain (hypothetical) robots made of silicon and steel would have the same conscious states as certain familiar biological beings with the same patterns of dispositions to peripheral behavior as the robots. Our findings provide evidence that the folk largely reject the view that silicon-based robots would have the sensations that they, the folk, attribute to the biological beings in question. (shrink)

John Steele interviewed Paul Davies on the subject of time. In that interview Davies stated that time is not a flow, which is correct. His reasoning for that conclusion, however, was flawed, based on a confused version of the flowing river analogy with time. A correct version of the analogy is presented, followed by an analysis of Davies’ argument. A detailed explanation is presented of the intrinsic nature of the type of change that time is. Transdisciplinary methodology based on isomorphies (...) is used to bring forth the nature of temporal change, and reveal why time is not a flow. (shrink)

It is sometimes argued that certain sentences of natural language fail to express truth conditional contents. Standard examples include e.g. Tipper is ready and Steel is strong enough. In this paper, we provide a novel analysis of truth conditional meaning using the notion of a question under discussion. This account explains why these types of sentences are not, in fact, semantically underdetermined, provides a principled analysis of the process by which natural language sentences can come to have enriched meanings in (...) context, and shows why various alternative views, e.g. so-called Radical Contextualism, Moderate Contextualism, and Semantic Minimalism, are partially right in their respective analyses of the problem, but also all ultimately wrong. Our analysis achieves this result using a standard truth conditional and compositional semantics and without making any assumptions about enriched logical forms, i.e. logical forms containing phonologically null expressions. (shrink)

Within the field of neuroscience, it is assumed that the central nervous system is divided into two functionally distinct components: the brain, which does the cognizing, and the spinal cord, which is a conduit of information enabling the brain to do its job. We dub this the “Cinderella view” of the spinal cord. Here, we suggest it should be abandoned. Marshalling recent empirical findings, we claim that the spinal cord is best conceived as an intrabodily cognitive extension: a piece of (...) biological circuitry that, together with the brain, constitutes our cognitive engine. To do so, after a brief introduction to the anatomy of the spinal cord, we briefly present a number of empirical studies highlighting the role played by the spinal cord in cognitive processing. Having so done, we claim that the spinal cord satisfies two popular and often endorsed criteria used to adjudicate cases of cognitive extension; namely the parity principle and the so-called “trust and glue” criteria. This, we argue, is sufficient to vindicate the role of the spinal cord as an intrabodily mental extension. We then steel our case considering a sizable number of prominent anti-extension arguments, showing that none of them poses a serious threat to our main claim. We then conclude the essay, spelling out a number of far-from trivial implications of our view. (shrink)

This piece is a comment on Quilty-Dunn, Jake, Nicolas Porot, and Eric Mandelbaum. 2023. “The Best Game in Town: The Reemergence of the Language-of-Thought Hypothesis across the Cognitive Sciences.” Behavioral and Brain Sciences 46: e261. -/- The target article signal boosts important ongoing work across the cognitive sciences. However, its theoretical claims, generative value, and purported contributions are – where not simply restatements of arguments extensively explored elsewhere – imprecise, noncommittal, and underdeveloped to a degree that makes them difficult to (...) evaluate. The article's apparent force results from engaging with straw rather than steel opponents. (shrink)

Hilary Greaves and David Wallace argue that conditionalization maximizes expected accuracy and so is a rational requirement, but their argument presupposes a particular picture of the bridge between rationality and accuracy: the Best-Plan-to-Follow picture. And theorists such as Miriam Schoenfield and Robert Steel argue that it's possible to motivate an alternative picture—the Best-Plan-to-Make picture—that does not vindicate conditionalization. I show that these theorists are mistaken: it turns out that, if an update procedure maximizes expected accuracy on the Best-Plan-to-Follow picture, it's (...) guaranteed to maximize expected accuracy on the Best-Plan-to-Make picture as well, in which case moving from the former to the latter can't help us avoid the conclusion that conditionalization is a rational requirement. If there's a problem with Greaves and Wallace’s argument, it must lie elsewhere. (shrink)

Ayn Rand and Immanuel Kant had profound disagreements, not just about the possible scope of knowledge, but (more importantly) about the possible scope of philosophy, especially metaphysics. This paper explores those disagreements, steel-manning both sides. My conclusion is that 1) both thinkers have worthwhile points to make, yet 2) Rand is guilty of poor scholarship while 3) Kant is guilty of appeal to ignorance. Despite the fallacious nature of (3), I stress that ignorance is not by itself something that philosophers (...) committed to objectivity should panic about. (shrink)

The foundation of a building connects the main body superstructure to the ground. Every form of foundation and footing have a unique application in a given location for a certain weather condition. Understanding the foundation work is crucial for carrying out building activities. Due to the variety of structures they support, foundations are frequently built in different subsoil conditions and are exposed to static loads. The proper evaluation of soil-bearing capacity is fundamental to the construction of various buildings. One of (...) the quick, easy, and affordable ways to determine soil carrying capacity is the plate load test. The effect of subsoil conditions on the test results is assessed and analyzed in thorough parametric investigations. An overview of axial static and dynamic plate load testing will be given in this study. This article presents detailed processes and schematics. In an effort to highlight the differences and shared characteristics of the results, computational test results of the static load plate test and the dynamic load plate test are contrasted. A load cell, a steel plate, a hydraulic actuator mounted on a big truck to apply a load, a load cell to measure the load, and one or more linear variable displacement transformers to measure the vertical displacements make up the test setup. The maximum thrust load that should be applied to a fixed or stationary actuator when it is not moving is known as a "static load depending on the actuator's static load capacity, we can determine what a safe load is. The maximum thrust load that should be applied to the actuator while it is moving is known as a dynamic load. Dynamic load capacity refers to how much force an actuator can exert when driven and extending or retracting. With each method's benefits and drawbacks considered, it can be determined that using them in various situations and agreeing to the confrontation of these tests for the purpose of comparing results is the best course of action in order to have a base that satisfies the construction standards. (shrink)

Mark Wilson argues that the standard categorizations of "Theory T thinking"— logic-centered conceptions of scientific organization (canonized via logical empiricists in the mid-twentieth century)—dampens the understanding and appreciation of those strategic subtleties working within science. By "Theory T thinking," we mean to describe the simplistic methodology in which mathematical science allegedly supplies ‘processes’ that parallel nature's own in a tidily isomorphic fashion, wherein "Theory T’s" feigned rigor and methodological dogmas advance inadequate discrimination that fails to distinguish between explanatory structures that (...) are architecturally distinct. One of Wilson's main goals is to reverse such premature exclusions and, thus, early on Wilson returns to John Locke's original physical concerns regarding material science and the congeries of descriptive concern insofar as capturing varied phenomena (i.e., cohesion, elasticity, fracture, and the transmission of coherent work) encountered amongst ordinary solids like wood and steel are concerned. Of course, Wilson methodologically updates such a purview by appealing to multiscalar techniques of modern computing, drawing from Robert Batterman's work on the greediness of scales and Jim Woodward's insights on causation. (shrink)

I examine the role of time-sensitivity in science by drawing on a discussion between Kevin Elliott and Daniel McKaughan and Daniel Steel, on the role of non-epistemic values in theory assessment and the epistemic status of speed of inference. I argue that: 1) speed supervenes on ease of use in the cases they discuss, 2) speed is an epistemic value, and 3) Steel’s account of values doesn’t successfully distinguish extrinsically epistemic from non-epistemic values. Finally, I propose an account of time-sensitivity.

Os dois ensaios aqui traduzidos: “Uma visita a uma glândula pineal”, publicado originalmente em 21 de abril de 1713 no número 35 do Guardian e a “A glândula pineal (continuação)”, publicado no dia 25 de abril, no número 39, formam uma unidade não apenas pela referência a ideia de glândula pineal concebida por Descartes como ponto de interação entre a alma e o corpo, mas também pela forma literária e pelo pseudônimo comum. Eles fazem parte de um conjunto de quatorze (...) ensaios atribuídos a George Berkeley, reunidos e publicados pela primeira vez apenas em 1871, no volume III da edição organizada por A. C. Fraser. Os ensaios publicados no Guardian foram escritos durante a permanência de Berkeley em Londres em 1713, quando Jonathan Swift (1667-1745) e Richard Steele (1672-1729), seus conterrâneos, contribuiriam para lhe abrir caminho no ambiente literário inglês. O principal objetivo de Berkeley ao publicar os ensaios foi o de defender o teísmo cristão contra os “livre-pensadores” da época, assumidos como materialistas e ateus. A tradução aqui apresentada foi realizada com base na edição organizada por Luce e Jessop. The Works of George Berkeley Bishop of Cloyne. Luce, A. A. and Jessop, T. E. London and Edimburgh: Nelson, 1948, v. 7, 185-192. (shrink)

Objective: Evidence suggests people experience an oral size illusion and commonly perceive oral size inaccurately; however, the nature of the illusion remains unclear. The objectives of the present study were to confirm the presence of an oral size illusion, determine the magnitude (amount) and direction (underestimation or overestimation) of the illusion, and determine whether immediately prior crossmodal perceptual experiences affected the magnitude and direction. Design: Participants (N = 27) orally assessed 9 sizes of stainless steel spheres (1/16 in to 1/2 (...) in) categorized as small, medium, or big, and matched them with digital and visual reference sets. Each participant completed 20 matching tasks in 3 assessments. For control assessments, 6 oral spheres were matched with reference sets of same-sized spheres. For primer-control assessments, similar to control, 6 matching tasks were preceded by cross-modal experiences of the same-sized sphere. For experimental assessments, 8 matching tasks were preceded by a cross-modal experience of a differently sized sphere. Results: For control assessments, small and medium spheres were consistently underestimated, and big spheres were consistently overestimated. For experimental assessments, magnitude and direction of the oral size illusion varied according to the size of the sphere used in the cross-modal experience. Conclusion: Results seemed to confirm an oral size illusion, but direction of the illusion depended on the size of the object. Immediately prior cross-modal experiences influenced magnitude and direction of the illusion, suggesting that aspects of oral perceptual experience are dependent upon factors outside of oral perceptual anatomy and the properties of the oral stimulus. (shrink)

The historic material culture produced by American Cold War nuclear weapons testing includes objects of scientific inquiry that can be generally categorized as being either ephemeral or enduring. Objects deemed to be ephemeral were of a less substantial nature, being impermanent and expendable in a nuclear test, while enduring objects were by nature more durable and long-lasting. Although all of these objects were ultimately subject to disappearance, the processes by which they were transformed, degraded, or destroyed prior to their disappearing (...) differ. Drawing principally upon archaeological theory, this paper proposes a functional dichotomy for categorizing and studying the historical trajectories of nuclear weapons testing technoscience artifacts. In examining the transformation patterns of steel towers and concrete blockhouses in particular, it explores an associated loss of scientific method that accompanies a science object's disappearance. (shrink)

Purpose. To determine the potential of deforming broaching for the improvement of efficiency of cutter chisels in the mining industry. Methodology. The study of the application of the technological process of deforming broaching was carried out based on the experimental research into conditions of assembly of press couplings corresponding to cutting rock-destroying tools, the working surface of which is reinforced with solid-alloy inserts. Findings. Based on the conducted research, a new process of assembling the crowns of cutter chisels with the (...) use of deforming broaching was developed. Originality. It was determined that the range of angles of inclination of generatrix of the working cone of the deforming element and the roll-treading lip of the insert, which are necessary for efficient machining and pressing in crowns of cutters, is 4–16°. It was proven that the “solid alloy-steel” press couplings for cutter chisels will have the maximum bearing capacity at total tension a/d0 ≤ 3 %. It was found that it is necessary to foresee the following distribution of tensions: to perform 2 % of deformation by preliminary deforming broaching, and 1 % ‒ by pressing in an insert Practical value. The use of deforming broaching makes it possible to increase the strength of fastening the inserts of cutter chisels by 2 times, to reduce specific consumption of the tool by 4.4 times, and to increase the average drilling rate by 4 times. (shrink)

Nutrient losses from sloping farmland in karst areas lead to the decline in land productivity and nonpoint source pollution. A specially tailored steel channel with an adjustable slope and underground hole fissures was used to simulate the microenvironment of the "dual structure" of the surface and underground of sloping farmland in a karst area. The artificial rainfall simulation method was used to explore the surface and underground runoff characteristics and nutrient losses from sloping farmland under different rainfall intensities. The effect (...) of rainfall intensity on the nutrient loss of farmland on karst sloping land was clarified. The results showed that the surface was the main route of runoff and nutrient loss during the rainy season on sloping farmland in karst areas. The influence of rainfall intensity on the nutrients in surface runoff was more substantial than that on underground runoff nutrients. Nutrient loss was more likely to occur underground than on the surface. The losses of total nitrogen, total phosphorus, and total potassium in surface and underground runoff initially increased and then gradually stabilized with the extension of rainfall duration and increased with increasing rainfall intensity and the amount of nutrient runoff. The output of nutrients through surface runoff accounted for a high proportion of the total, and underground runoff was responsible for a low proportion. Although the amount of nutrients output by underground runoff was small, it could directly cause groundwater pollution. The research results provide a theoretical reference for controlling land source pollution from sloping farming in karst areas. (shrink)

Digital innovation has become a most forwarded proposition of economic policies aiming for economic diversification and technological innovation. Moreover, it appears to be a feasible solution to the problem for Luxembourg that lacks the physical space to foster the development of an industrial sector that would require large areas. Also, diversifying from the well-established large steel industry complex is a plus. However, many obstacles can hinder the effective implementation of sharing economy principles in the digital world. This study underlines the (...) most active industry sector, transportation, which adopts the sharing economy principles. Moreover, it provides the status of sharing economy by the figures showing participation and motivation of people living in the Grand Duchy of Luxembourg. This study also highlights its challenges and related issues in terms of citizen participation and sharing economy based on digital platforms. (shrink)

There is an unacknowledged disagreement on what kind of dialogue best supports democracy. Many view democracy as analogous to a law court and so view “democratic dialogue” as a contest between competing advocates who have acquired the kind of “steel trap” critical thinking skills that are ideal for winning in the external marketplace of ideas. Others assume that the propensity to seriously reflect on opposing viewpoints within the minds of individuals is ideal for democratic maintenance. It will be argued here (...) that our love affair with “critical thinking” that tends to support an external battle of ideas harms democracy. It will be argued that the complexity of our common humanity, the complexity of our form of governance, the complexity of the approaches needed to face wicked problems, and the complexity of the internal engine of personal development requires that we learn to readily engage in open truth-seeking dialogue with those who hold opposing viewpoints and in so doing, enhance the dimensionality through which we view the world. With regard to the educational implications, this suggests that, since engaging in dialogue across difference is the essence of the pedagogical framework that anchors Philosophy for Children, Philosophy for Children ought to be embraced as an essential component of any educational enterprise that views cultivating democratic citizenship as part of its mandate. (shrink)

“Free will” puzzles are failed attempts to make freedom fit into forms of science. The failures seem puzzling because of widespread beliefs that forms of science describe and control everything. Errors in such beliefs are shown by reconstruction of forms of “platonic science” that were invented in ancient Greece and that have developed into modern physics. Like platonic Ideas, modern Laws of Physics are said to exercise hegemonic control through eternal, universal principles. Symmetries, rigidity and continuity are imposed through linear (...) forms that have been abstracted from geometry and indifference. Static and quasi-static forms presume placid equilibrium conditions and relaxation processes. Such forms, based on empty space, fail to describe actual material transformations that occur during the making of steel or the generation of snowflakes. They also fail to describe muscular movements and related bodily feelings of persons and animals that have actual life. Limitations of platonic science are overcome by means of new forms with the character of time, such as “beats” and saccadic, jumpy forms. New technologies of action and freedom generate and control temporal forms in proposed device models of brains and muscles. Some temporal forms have critical moments of transformation, resembling moments when persons exercise freedom, e.g., a moment of overtaking during a footrace or a moment of decision by a jury during a civil trial. (shrink)

DESENVOLVIMENTO EMBRIONÁRIO E DIFERENCIAÇÃO SEXUAL -/- E. I. C. da Silva Departamento de Agropecuária – IFPE Campus Belo Jardim Departamento de Zootecnia – UFRPE sede -/- 1.1 INTRODUÇÃO O sexo foi definido como a soma das diferenças morfológicas, fisiológicas e psicológicas que distinguem o macho da fêmea permitindo a reprodução sexual e assegurando a continuidade das espécies. Os processos de diferenciação sexual são realizados durante o desenvolvimento embrionário, onde ocorre a proliferação, diferenciação e maturação das células germinativas e primordiais, precursoras (...) de ovócitos e espermatozoides em fêmeas e machos, respectivamente. Assim, os embriões machos e fêmeas iniciam o seu desenvolvimento de forma semelhante, de modo que em ambos os sexos se estabelecem em estruturas idênticas a partir das quais se formarão os órgãos reprodutores correspondentes a cada sexo. O conhecimento da origem e do desenvolvimento do aparelho genital é indispensável para entender sua função e as alterações que produzem infertilidade ou esterilidade. 1.2 DETERMINAÇÃO DO SEXO CROMOSSÔMICO Nos mamíferos, o sexo cromossômico é determinado no momento da fertilização, quando um óvulo, que contém um cromossomo X, é fecundado por um espermatozoide portador de um cromossomo X ou um cromossomo Y. No primeiro caso, o complemento cromossômico seria XX, o que originaria uma fêmea (sexo homogamético), e no segundo daria como resultado um macho com a fórmula cromossômica XY (sexo heterogâmico). 1.3 A GÔNADA INDIFERENCIADA A primeira manifestação das gônadas se aprecia no embrião em forma de um par de eminências longitudinais chamadas cristas ou dobras gonodais, situadas em ambos os lados da linha média entre os mesonefros (rins em desenvolvimento) e do mesentério dorsal. Nos embriões dos mamíferos, as células germinativas primordiais (CGP) manifestam-se em estágios precoces do desenvolvimento, podendo ser detectadas pela primeira vez na metade da gastrulação. As CGP são células grandes, de citoplasma claro e núcleo grande e redondo, localizadas na parede do saco vitelino, perto do alantoide. Essas células possuem grande capacidade de proliferação e vão migrar desde o endoderma do intestino e o epitélio do saco vitelino, através do mesentério, até as cristas gonodais. Isso ocorre por volta do 26° dia da gestação no bovino. Sua migração realiza-se graças aos movimentos de translocação passiva e deslocamento ameboide ativo. Desconhece-se o mecanismo pelo qual estas células são dirigidas para as cristas gonodais, porém foram estudadas algumas moléculas que se expressam durante sua migração e que poderiam desempenhar um papel importante na diferenciação deste tipo celular. A fosfatase alcalina é uma enzima que tem sido usada como marcador de CGP para determinar a sua origem e migração. Num estudo recente, foi inserido um marcador fluorescente que se exprime unicamente nas células germinativas primordiais de embriões transgênicos, e utilizando este marcador e a fosfatase alcalina determinou-se a origem e o padrão de migração destas células. O primeiro sinal de diferenciação das células germinativas primordiais é a expressão de fosfatase alcalina, e esta apareceu pela primeira vez na parte mais posterior da linha primitiva. No sétimo dia de desenvolvimento no embrião do camundongo, o endoderma visceral (AF+) é substituído pelo endoderma definitivo (AF-) originado na parte anterior da linha primitiva. O fator de transcrição Oct-4 é expresso nas CGP de ambos os sexos, pelo que acredita-se estar envolvido na mantença a totipotêncialidade das células. O receptor tirosina quinase, cujo ligante é o fator de Steel, é outra das moléculas que expressam as CGP. Tem sido demonstrado que este receptor possui um papel muito importante na sobrevivência deste tipo celular. Existem outros fatores que promovem a sobrevivência e/ou proliferação de CGP in vitro. Em experiências realizadas com o fator de transformação beta I (TGFβ-I), observou-se que este tem um efeito negativo sobre a proliferação das CGP. Outra atividade que tem sido postulada a este fator é o de um agente quimioatraente que possivelmente possa direcionar a migração destas células para a gônada. a) Um formado pelas células germinativas primordiais (precursoras dos gametas masculinos ou femininos), rodeadas de células somáticas das quais posteriormente se derivarão as células de Sertoli no macho e as células da granulosa na fêmea. b) O tecido que formará o estroma da gônada: tecido conjuntivo, vasos sanguíneos e as células intersticiais com atividade esteroidogênica (células de Leydig no testículo e a teca interna do ovário). As células somáticas do primórdio gonodal originam-se do mesoderma. Inicialmente são de três tipos: mesenquimáticas, mesoteliais e endoteliais. As células mesenquimáticas e mesoteliais iniciam grande atividade proliferativa ao chegar as CGP. Observa-se então uma condensação de células de origem mesotelial e mesenquimatoso que forma um agregado compacto denominado "blastema gonodal". A partir deste primórdio embrionário, diferenciam-se dois tecidos gonodais: os cordões sexuais e o estroma. Os cordões sexuais são arranjos epiteliais que se encontram delimitados por uma folha basal, e dentro deles encontramos as CGP. Por sua vez, no estroma encontram-se células do tipo mesenquimático e vasos sanguíneos. Neste momento, as gônadas são indiferenciadas e bipotencialmente sexuais, sendo impossível diferenciar, morfologicamente, uma gônada masculina de uma feminina, mas no caso dos machos genéticos já existe uma diferenciação da gônada a nível molecular. Nesta fase já se encontram presentes as estruturas das quais se desenvolvem os dutos mesonéfricos ou de Wolff precursores do aparelho genital masculino e os dutos paramesonéfricos ou de Müller que darão origem ao aparelho reprodutor feminino. Há uma série de fatores envolvidos no desenvolvimento precoce da gônada, entre os quais o fator esteroidogênico I (SFI: Steroidogenic fator l), que é um membro da subfamília de receptores nucleares, receptores órfãos. Este fator de transcrição tem um local de ligação ao DNA composto por dois dedos-de-Zinc. O SFI foi identificado como um ativador de genes envolvidos na biossíntese de esteroides em diferentes células. O SFI está presente durante o desenvolvimento embrionário em regiões associadas com funções endócrinas como gônadas, adrenais, pituitárias e hipotálamos. Os animais homozigotos para o gene SFI defeituoso, necessitam de gônadas e adrenais e têm a função gonadotrófica alterada. Os ratos sem SFI carecem de gonadotrofos e têm um desenvolvimento anormal do núcleo ventro-medial do hipotálamo; em particular as gônadas deixam de se desenvolver entre os dias 11 a 15 e degeneram-se por apoptose. No entanto, a crista genital forma-se e é colonizada pelas células germinativas, o que indica que estas continuam a receber o sinal adequado para a sua migração. Portanto, o SFI não está envolvido no desenvolvimento precoce da gônada e do sistema urogenital, mas parece estar envolvido na manutenção do crescimento das células somáticas presentes na gônada indiferenciada. O gene associado ao tumor de Wilms (WTI: Wilm's tumor Associated) está envolvido no desenvolvimento da gônada e do rim. Durante o desenvolvimento embrionário, WTI se expressa em todo o mesoderma intermediário e posteriormente na gônada indiferenciada, bem como no rim em formação. WTI regula o sinal indutivo do mesênquima para o epitélio celômico dos mesonefros. Se este for o caso, então WTI é responsável pelo crescimento da crista genital ao dirigir a entrada do epitélio celômico. Dado que estas células darão origem às células de Sertoli, a carência de WTI pode causar o desenvolvimento de embriões XY como fêmeas simplesmente porque não se formam as células de Sertoli. Em geral, todos os genes importantes na diferenciação do mesoderma intermediário e do sistema urogenital intervêm no desenvolvimento da gônada precoce. 1.4 DIFERENCIAÇÃO GONODAL O desenvolvimento das gônadas e ductos genitais descritos até o momento, é o mesmo para ambos os sexos. Igualmente, os genes descritos, que estão envolvidos no desenvolvimento das gônadas, ductos genitais e migração das células germinativas, afetam igualmente os embriões com genótipo XX ou XY. A gônada primitiva consiste anatomicamente de uma medula (interna) e uma crosta (externa), e de acordo com o local onde ocorre a colonização das células germinativas, diferenciara em testículo ou um ovário, respectivamente. Nos mamíferos, a primeira manifestação estrutural de diferenciação sexual é detectada na gônada dos machos, onde as células germinativas estão localizadas na medula. A diferenciação do testículo inicia-se quando os cordões sexuais se separam do epitélio celômico como consequência dos arranjos produzidos por uma invasão do mesênquima e vasos sanguíneos que provoca a compactação dos cordões, agora denominados cordões testiculares. As células que rodeiam os cordões se achatam e formam as células mioides, que são responsáveis pela formação das membranas basais. As células do epitélio interno, ou seja, as células de Sertoli, têm duas funções principais: o suporte das CGP e a síntese da hormona antimulleriana, responsável pela regressão dos ductos de Müller e secretada durante o período de diferenciação sexual. As células do estroma que rodeiam os cordões testiculares diferenciam-se para formar vários tipos de células: células mioides, fibroblastos, endotélio e células de Leydig, que são as mais importantes pela sua atividade endócrina. Posteriormente, os cordões testiculares dão origem aos túbulos seminíferos, que contêm o epitélio que produzirá os espermatozoides ao chegar à puberdade. Na fêmea, durante os estágios iniciais de diferenciação gonodal, não se observam mudanças em relação à gônada indiferenciada, só pode-se observar um certo crescimento devido à proliferação de células somáticas e germinativas. As células germinativas iniciam um período de proliferação, que termina com o início da meiose. Iniciada a meiose, dá-se o processo de foliculogênese; neste momento os cordões epiteliais se fragmentam, de tal maneira que cada ovócito fica rodeado de células epiteliais cobertas por uma folha basal fina (figura 1). Para que a gônada primitiva se desenvolva em testículo é indispensável a presença do cromossoma Y, independentemente do número de cromossomas X que contenha o genoma de um indivíduo. O gene determinante do testículo encontra-se localizado no cromossoma Y, denominado sry em ratos e SRY em humanos. O gene sry se expressa durante o desenvolvimento embrionário na crista genital de embriões de camundongos. A expressão é detectável no dia 10,5, pouco depois do aparecimento das cristas genitais, atinge o seu máximo durante o dia 11,5 e mantém-se até pouco depois de ocorrerem os primeiros sinais morfológicos de diferenciação testicular no dia 12,5. Este padrão de expressão é compatível com a teoria de que sry atua induzindo a ativação dos genes (figura 2) que conduzem ao desenvolvimento testicular, sem que exista a necessidade da expressão contínua de sry para manter a diferenciação do testículo após o dia 12,5. Como mencionado anteriormente, a gônada primitiva é composta por vários tipos de células. No entanto, as células germinativas primordiais não são o local de expressão do sry, já que os embriões que necessitam de células germinativas mantêm a expressão de sry e desenvolvem o sexo gonodal normalmente. As células somáticas na gônada em desenvolvimento incluem também as células de suporte. Sabe-se que é nestas células que o sry é expresso para que se diferenciem em células de Sertoli, e a expressão transitória de sry indica que deve ativar a outros genes para a manutenção das células de Sertoli. Uma vez diferenciadas as células de Sertoli, elas se encarregarão da diferenciação do resto das células na gônada. -/- Figura 1: Representação da diferenciação dos órgãos genitais internos. Adaptado de BRONSON, 1989. Figura 2: Cascada de genes envolvidos na diferenciação sexual, adaptado de KOOPMAN, 1999. O fator sry é necessário para a diferenciação do testículo. Embora não se conheçam os genes que provavelmente regulam esse gene, estudos realizados em camundongos demonstram que este gene parece coordenar-se com certos genes autossômicos. Entre estes genes autossômicos, o sox9, que é produzido pelas células de Sertoli uma vez que são estimuladas por sry, de modo que sox9 é um dos genes relacionados estruturalmente com sry. O Sox9 funciona como um fator de transcrição, mas não se sabe se a proteína tem qualquer outra função estrutural; este gene exprime-se abundantemente nos condrócitos e está relacionado com defeitos do aparelho ósseo chamados displasia campomélica. Curiosamente, os pacientes XY com esta condição sofrem frequentemente de reversão do sexo. O Sox9 é um dos poucos genes, além do SRY, do qual as mutações demonstraram interferir com a determinação sexual masculina. No entanto, apenas 75% dos pacientes com anomalias esqueléticas de tipo displasia campomélica têm reversão sexual e não foram encontrados casos de reversão sexual devido a um defeito de Sox9 que não seja acompanhado de defeitos esqueléticos. Isso indica que o Sox9 é apenas um membro da rede de genes que são ativados para determinar a diferenciação sexual, enquanto a rota que rege a condrogênese é mais sensível a perturbações deste. O momento em que se detecta a expressão do gene Sox9 (11dpc em ratos) coincide com a máxima expressão de sry, o que poderia indicar a possibilidade de que sry regule positivamente a Sox9. De fato, na região do promotor de Sox9 há um local de união ao que potencialmente se pode unir o sry. A expressão de Sox9 durante a diferenciação sexual sugere um papel abaixo de sry na diferenciação das células de Sertoli. O cromossoma X também é importante na diferenciação gonodal. O gene DAX-I foi isolado do lócus DSS (Dosage sensitive sex reversal) do cromossoma X. DAX-I é parte da cascata de determinação sexual, mas não é necessário para a formação do testículo. DAX-I é um membro dos receptores nucleares conhecidos como receptores órfãos. Este gene demonstrou ser um poderoso repressor da transcrição de SFI e de vários genes. Os padrões de expressão de DAX-I são complementares daqueles de SFI, ambos expressos nas cristas genitais. Em resumo, dada a evidência exposta, desenvolveu-se a hipótese de que DAX-I é um antagonista de sry; esse antagonismo é dependente dos níveis relativos de DAX-I e sry e de um limiar que varia de espécie para espécie. A DAX-I foi classificada como o gene antitestículo. Na fêmea (cariótipo XX) é importante que ocorra a inativação de um dos cromossomas sexuais X para que se mantenha o equilíbrio genético ao igualar o conteúdo de DNA dos cromossomas. Esse cromossoma inativado constitui o chamado corpúsculo de Barr. No entanto, para que a meiose se realize, é necessário dos dois cromossomas X ativos nos ovócitos para assegurar a diferenciação ovárica e a fertilidade. 1.5 DIFERENCIAÇÃO DOS DUCTOS SEXUAIS O embrião possui, além das gônadas indiferenciadas, dois sistemas de ductos: os de potencialidade masculina denominam-se ductos de Wolff ou mesonéfricos, e os de potencialidade feminina se chamam ductos de Müller ou paramesonéfricos (figura 1). Se a diferenciação gonodal levou à formação de um testículo, a partir do ducto mesonéfrico ou de Wolff se desenvolverão os ductos eferentes, o epidídimo, os ductos deferentes e as vesículas seminais. As hormonas importantes no desenvolvimento do aparelho genital masculino são a testosterona, produzida pelas células de Leydig, e sua forma 5α reduzida, a 5α di-hidrotestosterona. Acredita-se que a testosterona é responsável pela virilização dos ductos de Wolff, e a di-hidrotestosterona dos órgãos genitais externos. No macho, os canais de Müller atrofiam-se devido à ação de uma hormona fetal de origem testicular denominada hormona inibidora das estruturas de Müller (HIM) ou hormona antimulleriana. Este processo começa assim que os cordões espermáticos se formam e se diferenciam as células de Sertoli. A existência de HIM foi proposta baseada em estudos realizados em bezerras freemartin, devido à existência de uma hormona responsável pela atresia dos ductos de Müller que na fêmea dá origem ao útero e aos ovidutos. Essa hormona provoca a involução do aparelho genital do bovino nas gestações gemelares nas quais os produtos de diferente sexo têm comunicação sanguínea por ter ocorrido a anastomose dos vasos de ambas as placentas (figura 3). A HIM é uma glicoproteína pertencente à subfamília de TGFβ, é expressa pelas células que darão origem às células de Sertoli e é um dos primeiros marcadores de diferenciação nestas células. A HIM é secretada na vida adulta pelas células de Sertoli no testículo e por células da granulosa no ovário. No rato a HIM é expressa-se no 12° dia em um teste padrão que segue muito de perto o aumento na expressão de sry. No macho, esta secreção de HIM continua durante a vida fetal e adulta, contudo os níveis de HIM declinam na puberdade devido a um aumento na secreção de testosterona. Vários fatores intervêm na regulação do gene de HIM, incluindo os acima descritos SFI e Sox9. O gene HIM contém segmentos de DNA que são conservados em várias espécies de vertebrados. Existe um nexo de ligação para SFI, que ativa a transcrição de HIM. A mutação no local de ligação de SFI resulta em reversão do sexo em indivíduos XY incluindo genitais femininos normais, presença de um útero formado enfatizando a importância de SFI na determinação sexual e na expressão de HIM. Embora SFI seja um bom candidato como regulador de HIM, é expresso em outras células, como as de Leydig e adrenais, que não expressam HIM. Em contrapartida, Sox9 é expresso unicamente nas células de Sertoli que são as produtoras de HIM. O gene HIM também tem um nexo de ligação para Sox9. Além disso, Sox9 pode atuar sinergicamente com SFI para promover a secreção de HIM. Ao contrário destes dois fatores de transcrição, DAX-I antagoniza a ação de Sox9 e provavelmente SFI sobre o promotor de HIM. Assim, para que as células de Sertoli secretem HIM, a transcrição de DAX-I deve diminuir. Figura 3: Representação da diferenciação dos órgãos genitais externos. Adaptado de BRONSON, 1989. Os ductos de Wolff tornam-se o sistema de ejaculação do macho. A porção mais próxima dos testículos dá origem ao epidídimo, a parte central ao ducto deferente e a porção mais distal às vesículas seminais. A próstata e a parte membranosa da uretra do macho desenvolvem-se a partir da porção pélvica do seio urogenital. A virilização e diferenciação dos ductos de Wolff dependem da produção de testosterona pelo testículo. Quanto aos órgãos genitais externos do macho, o tubérculo genital é ampliado e as dobras uretrais se fundem para formar a uretra peniana. A fusão das dobras uretrais aproxima os tubérculos genitais para formar o escroto (figura 4). Figura 4: Diferenciação do aparelho genital da fêmea e do macho. Adaptado de KOOPMAN, 1989. A diferenciação dos órgãos genitais da fêmea ocorre de forma passiva, já que a ausência de testículos e por isso da hormona inibidora dos ductos de Müller (HIM), assim como dos andrógenos virilizantes, favorece o desenvolvimento dos ductos de Müller, enquanto os de Wolff sofrem atrofia. A porção cefálica dos ductos de Müller dá origem aos ovidutos, que na sua terminação caudal se fundem com o útero. O contato dos ductos de Müller com o seio urogenital induz uma intensa proliferação celular que resulta na formação da área uterovaginal localizado entre o seio urogenital e os ductos de Müller. As células do prato uterovaginal proliferam e aumentam a distância entre as duas estruturas criando o espaço que formará a vagina quando o prato é canalizado e forma um lúmen. Em contraste com o que ocorre no macho, na fêmea a maior parte do seio urogenital se mantém exposta na superfície da abertura onde desembocam a vagina e a uretra. O tubérculo urogenital da fêmea tem um crescimento limitado e forma o clitóris. A sequência de passos da diferenciação sexual do aparelho genital é resumida na tabela 1. Tabela 1: Destino em desenvolvimento dos rudimentos sexuais dos fetos macho e fêmea dos mamíferos -/- Rudimento sexual Macho Fêmea Gônada Testículo Ovário Ductos de Müller (Paramesonéfricos) Vestígios Útero, parte da vagina, ovidutos Ductos de Wolff (Mesonéfricos) Ductos eferentes deferentes, epidídimo, vesículas seminais Vestígios Seio urogenital Uretra, próstata, glândulas bulbouretrais Parte da vagina, uretra, vestíbulo, glândulas vestibulares Tubérculo genital Pênis Clitóris Pregas vestibulares Escroto Lábios vulvares Fonte: HAFEZ, 2004. 1.6 DIFERENCIAÇÃO SEXUAL DO HIPOTÁLAMO Os processos de diferenciação sexual não se limitam apenas às células somáticas do organismo do feto, mas incluem também os centros nervosos superiores do cérebro. Assim, da mesma maneira que a gônada e os ductos sexuais se desenvolvem para o tipo feminino ou masculino, propôs-se que o cérebro pode ser "masculinizado" ou permanecer "Feminizado". A diferenciação do hipotálamo vai depender do ambiente esteroidal do neonato e ocorre na fase perinatal. Estes eventos serão de grande transcendência na vida reprodutiva do indivíduo. Tanto a fêmea como o macho nascem com a capacidade de secreção de gonadotropinas de acordo com um padrão cíclico; contudo, no macho, a exposição do hipotálamo à ação dos andrógenos testiculares durante os primeiros dias da vida extrauterina provoca a masculinização, com o qual o hipotálamo do macho é programado para que a secreção de gonadotropinas se realize a um ritmo relativamente constante por parte da hipófise (secreção tônica). Na fêmea, tanto a secreção tônica como a cíclica se conservam. No entanto, observou-se que a injeção de testosterona ou o transplante de testículo na rata fêmea durante os primeiros dias de vida, suprime a sua futura atividade estral (secreção cíclica). Por outro lado, se os ovários forem transplantados para o rato macho normal castrado na idade adulta, o animal não desenvolve qualquer atividade cíclica, mas se os machos transplantados forem castrados ao nascer, o ovário é capaz de efetuar mudanças cíclicas e ovulações. Isto foi demonstrado em roedores, mas não em animais domésticos ou na espécie humana. Portanto, o padrão de secreção de gonadotropinas, seja cíclico ou tônico, não depende da hipófise, mas do hipotálamo e sua correta diferenciação. 1.7 CONCLUSÕES A maioria dos conhecimentos no campo da biologia do desenvolvimento e, muito especificamente, dos processos de diferenciação sexual têm sido originados de estudos relacionados com desordens congênitas, que na sua maioria devem-se a defeitos de genes específicos. A análise detalhada destas desordens permitiu entender alguns mecanismos endócrinos, moleculares e genéticos envolvidos na diferenciação sexual. A identificação do gene sry como determinante do testículo foi uma contribuição crucial e abriu as portas à compreensão dos mecanismos moleculares e celulares relacionados com o desenvolvimento do testículo. Se este gene não estiver presente, é criado um programa genético alternativo para levar a cabo a diferenciação gonodal para o ovário. Finalmente, devemos ter presente que é necessária uma correlação entre mudanças morfológicas e expressão de genes durante o desenvolvimento para entender os mecanismos relacionados com a diferenciação. -/- Apoio -/- Realização -/- REFERÊNCIAS BIBLIOGRÁFICAS ANDERSON, Robert et al. The onset of germ cell migration in the mouse embryo. Mechanisms of development, v. 91, n. 1-2, p. 61-68, 2000. AUSTIN, Colin Russell; SHORT, R. V. Reproduction in Mammals: Volume 1, Germ Cells and Fertilization. Londres: Cambridge University Press, 1972. BRONSON, Franklin H. Mammalian reproductive biology. Chicago: University of Chicago Press, 1989. BUEHR, Mia. The primordial germ cells of mammals: some current perspectives. Experimental cell research, v. 232, n. 2, p. 194-207, 1997. BYSKOV, Anne G. Differentiation of mammalian embryonic gonad. Physiological reviews, v. 66, n. 1, p. 71-117, 1986. CAPEL, Blanche et al. Migration of mesonephric cells into the mammalian gonad depends on Sry. Mechanisms of development, v. 84, n. 1-2, p. 127-131, 1999. CAPEL, Blanche. The battle of the sexes. Mechanisms of development, v. 92, n. 1, p. 89-103, 2000. DERIVAUX, Jules; BARNABÉ, Renato Campanarut. Reprodução dos animais domésticos. Zaragoza: Acribia, 1980. DOMENICE, Sorahia et al. Aspectos moleculares da determinação e diferenciação sexual. Arquivos Brasileiros de Endocrinologia & Metabologia, v. 46, n. 4, p. 433-443, 2002. DONAHOE, Patricia K. et al. Mullerian inhibiting substance activity in bovine fetal, newborn and prepubertal testes. Biology of reproduction, v. 16, n. 2, p. 238-243, 1977. HAFEZ, Elsayed Saad Eldin; HAFEZ, B. Reprodução animal. São Paulo: Manole, 2004. HANLEY, Neil A. et al. Steroidogenic factor 1 (SF-1) is essential for ovarian development and function. Molecular and cellular endocrinology, v. 163, n. 1-2, p. 27-32, 2000. HIORT, Olaf; PAUL-MARTIN, H. The molecular basis of male sexual differentiation. European journal of endocrinology, v. 142, n. 2, p. 101-110, 2000. HOLY, Lubos; MARTÍNEZ JÚSTIZ, G. Colab. Biología de la reproducción bovina. Havana: Revolucionária, 1975. JOSSO, Nathalie et al. The role of anti-Müllerian hormone in gonadal development. Molecular and cellular endocrinology, v. 145, n. 1-2, p. 3-7, 1998. JOST, Alfred et al. Studies on sex differentiation in mammals. In: Proceedings of the 1972 Laurentian Hormone Conference. Londres: Academic Press, 1973. p. 1-41. KNOBIL, Ernst. Knobil and Neill's physiology of reproduction. EUA: Gulf Professional Publishing, 2006. KOFMAN ALFARO, S.; MERCHANT LARIOS, H.; PEREZ PALACIOS, G. Diferenciacion sexual. I. Bases biologicas del dimorfismo sexual. Rev. invest. clín, p. 349-59, 1982. KOOPMAN, Peter. Sry and Sox9: mammalian testis-determining genes. Cellular and Molecular Life Sciences CMLS, v. 55, n. 6-7, p. 839-856, 1999. MCDONALD, L. E. Veterinary endocrinology. Lea & Febiger, Philadelphia, Pa, 1969. MEIZEL, S.; JOHNSON, M. H. Development in mammals. MH Johnson, Ed, v. 3, p. 1-64, 1978. MELLO, Maricilda Palandi de; ASSUMPÇÃO, Juliana de G.; HACKEL, Christine. Genes envolvidos na determinação e diferenciação do sexo. Arquivos Brasileiros de Endocrinologia & Metabologia, v. 49, n. 1, p. 14-25, 2005. -/- REFERÊNCIAS BIBLIOGRÁFICAS MERCHANT-LARIOS, H. Ovarian differentiation. The Vertebrate Ovary, p. 47-81, 1978. MIES FILHO, Antonio. Reprodução dos animais. Porto Alegre: Sulina, 1987. NEF, Serge; PARADA, Luis F. Hormones in male sexual development. Genes & Development, v. 14, n. 24, p. 3075-3086, 2000. PARKER, Keith L.; SCHEDL, Andreas; SCHIMMER, Bernard P. Gene interactions in gonadal development. Annual review of physiology, v. 61, n. 1, p. 417-433, 1999. SWAIN, Amanda; LOVELL-BADGE, Robin. Mammalian sex determination: a molecular drama. Genes & development, v. 13, n. 7, p. 755-767, 1999. WILHELM, Dagmar; PALMER, Stephen; KOOPMAN, Peter. Sex determination and gonadal development in mammals. Physiological reviews, v. 87, n. 1, p. 1-28, 2007. WILSON, Jean D.; GRIFFIN, James E.; GEORGE, Fredrick W. Sexual differentiation: early hormone synthesis and action. Biology of reproduction, v. 22, n. 1, p. 9-17, 1980. -/- Emanuel Isaque Cordeiro da Silva Belo Jardim, 07 de Maio de 2020. (shrink)

Już w 1775 r. Joshua Steele sformułował tezę o występowaniu równych pod względem czasowym interwałów – nie tylko w muzyce, ale również w mowie ludzkiej. Tak zwana teoria izochronizmu stała się w późniejszym okresie wyjściowym kryterium dla typologicznego podziału języków świata pod względem zjawisk rytmicznych. Na podstawie badań akustyczno-audytywnych niemożliwe było jednak znalezienie empirycznych dowodów co do równości odstępów pomiędzy sylabami akcentowanymi w językach grupy stress-timed ani co do równego czasu trwania poszczególnych sylab w językach typu syllable-timed. Tak więc pierwotny (...) typologiczny podział języków według dwóch typów rytmicznych okazał się nieuzasadniony. Celem niniejszego artykułu jest ukazanie innych kryteriów typologicznego opisu języków pod względem rytmu, który ma duże znaczenie w dziedzinie językoznawstwa kontrastywnego oraz nauczania języków obcych. (shrink)

Trung Quốc là nền kinh tế lớn hàng đầu thế giới, vận hành với hiệu suất cao để đáp ứng nhu cầu sinh kế của hơn 1,4 tỷ người dân, và cung cấp một lượng hàng hóa công nghệ, tiêu dùng và cả nông phẩm tới thế giới. Hệ quả tất yếu của quá trình tăng trưởng liên tục hơn 4 thập niên là việc sử dụng tài nguyên, và trong quá trình sản xuất, chế tạo, chế biến cũng sản (...) sinh ra một lượng khí nhà kính (GHG) tích lũy khổng lồ phát thải vào khí quyển. Trong một thống kê được đăng trên The Guardian năm 2017, thế giới đã nhận thấy trong giai đoạn 1988-2015, 100 tổ hợp công nghiệp hàng đầu thế giới chịu trách nhiệm cho việc phát thải tới 71% tổng tồn lượng GHG trong khí quyển. Dẫn đầu danh sách này trên phương diện quốc gia là Trung Quốc, với thống kê chỉ 5 đại công ty Trung Quốc đã chiếm tới gần 17% tổng lượng phát thải, trong đó tổ hợp ngành than có trách nhiệm lớn nhất, tới 14,32%. Sau những tiến bộ công nghệ vượt bậc cũng như tích lũy thặng dư nền kinh tế, quá trình hiện đại hóa ở Trung Quốc sang thời kỳ Chủ tịch Tập Cận Bình đã chuyển hướng sang bảo vệ môi trường với các mục tiêu phát thải nghiêm ngặt. Chẳng hạn như xác định nhóm ngành sản xuất gang thép với vai trò lớn trong mục tiêu giảm phát thải GHG, chính phủ và lãnh đạo công nghiệp liên tục tìm kiếm giải pháp cho sự hạn chế nguồn tài nguyên, thúc đẩy khuếch tán công nghệ, ứng dụng tiến bộ trong giảm phát thải và thu giữ, chôn lấp các-bon, thích hợp với ngành thép, dựa trên đánh giá bằng hệ thống phân tích hướng tới giải quyết mục tiêu biến đổi khí hậu có tên viết tắt “C3IAM/NET-IS.”. (shrink)