Individuals differ considerably in their emotion experience. Some experience emotions in a highly differentiated manner, clearly distinguishing among a variety of negative and positive discrete emotions. Others experience emotions in a relatively undifferentiated manner, treating a range of like-valence terms as interchangeable. Drawing on self-regulation theory, we hypothesised that individuals with highly differentiated emotion experience should be better able to regulate emotions than individuals with poorly differentiated emotion experience. In particular, we hypothesised that emotion differentiation and emotion regulation would (...) be positively related in the context of intense negative emotions, where the press for emotion regulation is generally greatest. To test this hypothesis, participants' negative and positive emotion differentiation was assessed using a 14-day diary protocol. Participants' regulation of negative and positive emotions was assessed using laboratory measures. As predicted, negative emotion differentiation was positively related to the frequency of negative emotion regulation, particularly at higher levels of emotional intensity. (shrink)

Highly mobile computing devices promise to improve quality of life, productivity, and performance. Increased situation awareness and reduced mental workload are two potential means by which this can be accomplished. However, it is difficult to measure these concepts in the ‘wild’. We employed an ultra-portable battery operated and wireless functional near infrared spectroscopy (fNIRS) to non-invasively measure hemodynamic changes in the brain’s prefrontal cortex. Measurements were taken during navigation of a college campus with either a hand-held display, or an augmented (...) reality wearable display. Hemodynamic measures were also paired with secondary tasks of visual perception and auditory working memory to provide behavioral assessment of situation awareness and mental workload. Navigating with an augmented reality wearable display produced the least workload during both secondary tasks. The hemodynamics associated with errors were also different between the two devices. Errors with an augmented reality wearable display were associated with increased prefrontal activity and the opposite was observed for the hand-held display. This suggests that the cognitive mechanisms underlying errors between the two devices differ. These findings show fNIRS is a valuable tool for assessing new technology in ecologically valid settings and that head-mounted displays offer benefits with regards to mental workload while navigating, and potentially superior situation awareness with improved display design. (shrink)

In this third installment of his series on key, underappreciated ideas in Ayn Rand's epistemology, the author discusses the nature of differentiation and integration as the functional essence of consciousness and applies that insight to various cognitive and noncognitive processes of awareness, with a special emphasis on logic and illogic. He offers an extended analysis of the fallacies of “Frozen Abstraction” and “False Alternative,” as well as critiques of a long-standing Objectivist conflation of falsity and contradiction and a relatively (...) more recent Objectivist error, the fallacy of “genuine awareness.”. (shrink)

Studies on the ethical culture of organizations have mainly focused on ethical culture at the organizational level. This study explores ethical culture at the team level because this can add a more detailed understanding of the ethics of an organization, which is necessary for more customized and effective management interventions. To find out whether various teams within an organization can have different ethical cultures, we employ the differentiation perspective and conduct a survey of 180 teams from one organization. The (...) results show that there are significant differences between the ethical cultures of teams. These differences are relevant given the different relationships that were established between high and low clusters of team ethical culture and two outcome variables. The results also show that the dimensions of ethical cultures among teams have different patterns, which indicates the usefulness of using a multidimensional scale for capturing further differences among team ethical cultures. (shrink)

Studies on the ethical culture of organizations have mainly focused on ethical culture at the organizational level. This study explores ethical culture at the team level because this can add a more detailed understanding of the ethics of an organization, which is necessary for more customized and effective management interventions. To find out whether various teams within an organization can have different ethical cultures, we employ the differentiation perspective and conduct a survey of 180 teams from one organization. The (...) results show that there are significant differences between the ethical cultures of teams. These differences are relevant given the different relationships that were established between high and low clusters of team ethical culture and two outcome variables. The results also show that the dimensions of ethical cultures among teams have different patterns, which indicates the usefulness of using a multidimensional scale for capturing further differences among team ethical cultures. (shrink)

Studies on the ethical culture of organizations have mainly focused on ethical culture at the organizational level. This study explores ethical culture at the team level because this can add a more detailed understanding of the ethics of an organization, which is necessary for more customized and effective management interventions. To find out whether various teams within an organization can have different ethical cultures, we employ the differentiation perspective and conduct a survey of 180 teams from one organization. The (...) results show that there are significant differences between the ethical cultures of teams. These differences are relevant given the different relationships that were established between high and low clusters of team ethical culture and two outcome variables. The results also show that the dimensions of ethical cultures among teams have different patterns, which indicates the usefulness of using a multidimensional scale for capturing further differences among team ethical cultures. (shrink)

ABSTRACTPrevious research has found that individuals vary greatly in emotion differentiation, that is, the extent to which they distinguish between different emotions when reporting on their own fe...

In modern academic career systems there are a large number of entry positions, much smaller numbers of intermediate positions, and still fewer full professorships. We examine how this system has developed in Germany, the country where the modern academic system was introduced, tracing the historical development of academic positions since the early 19th century. We show both a differentiation and professionalization. At first, professorships and private lecturer positions were the only formal positions, but later, lower formal academic positions emerged. (...) Over the whole period, the share of higher academic positions steadily decreased. This differentiation process was closely connected to professionalization: remuneration through salaries was extended from professors to almost everyone working in the German academic system. We propose that the process of differentiation and professionalization was induced by the expansion and democratization of higher education. Finally, our study shows that the opportunities for PhDs to obtain salaried doctoral positions have increased since the 1950s. On the other hand, opportunities for PhDs to become a professor or obtain another tenured job have decreased since the 1980s due to a slowdown of higher education expansion. (shrink)

Nineteenth-century scientist Hermann von Helmholtz’s peculiar wavering between empiricism and transcendentalism in his philosophy of science in general, and in his theory of perception in particular, is a much debated and well-documented topic in the history and philosophy of science. This contribution aims at providing a fresh angle on this classical issue, by considering Helmholtz’s account of differential consciousness against the background of a centuries-old philosophical debate between the empiricist tradition and the tradition of transcendental idealism. By placing Helmholtz’s psychology (...) against the background of a historical narrative stretching from Hume to Fichte, one can gain insight into the possible merits of his empirico-transcendentalism with regard to the problem of differentiation. More particularly, it is argued that Helmholtz’s psychology tilted towards transcendentalism when met with the classical theoretical problems of strict empiricism in dealing with the foundation of consciousness, most notably circularity and infinite regress. Without claiming that Helmholtz’s theorizing presented a self-conscious attempt to overcome the latter issues, his well-known wavering between perspectives in general, and his appropriation of the a priori in particular, might have served him well in avoiding the deadlocks of empiricism. As noted at the end, however, Helmholtz’s account produced complex philosophical problems of its own. (shrink)

Worship as the work of the people of God does not arise in a vacuum. It is contextual and cultural. In the areas of the world, long designated as the mission field, many developments were transported to countries in the global south and imposed on local peoples. This was true of the arrival of Presbyterians who came to settle in southern Africa. Presbyterians imported two differing traditions of worship, the evangelical and the liturgical, and introduced them to the indigenous peoples (...) they encountered. They were adopted without adaptation and have largely followed their European ancestors and contemporaries. Africans have largely followed their missionary mentors but have found ways of subverting these traditions by forming a new tradition by blending aspects of each and adding their own African brand of Spirit inspired and led. worship while their mentors pay only lip service to their African colleagues. Contribution: This article highlights the historical continuities in the worship of a mainline Church of European Origin (CEO) with their ecclesiastical and ecumenical source(s). This is in discontinuity with the worship traditions of African Christian communities, which are less formal and tend to incline towards the charismatic and Pentecostal traditions with their freedom of expression of faith rather than the more cerebral forms of expression. (shrink)

Musical flutes constructed from bird bone and mammoth ivory begin to appear in the archaeological record from around 40,000 years ago. Due to the different physical demands of acquiring and working with these source materials in order to produce a flute, researchers have speculated about the significance—aesthetic or otherwise—of the use of mammoth ivory as a raw material for flutes. I argue that biological signaling theory provides a theoretical basis for the proposition that mammoth ivory flute production is a signal (...) of increasing social differentiation in Upper Palaeolithic human life. (shrink)

The sources show that two different groups of sheikhs were followed in the Hanafi usūl al-fiqh: ‘Iraqi and Samarqandi sheikhs. However, the perception of followers of ‘Iraqi sheikhs formed the dominant Hanafī tradition. This situation has caused different approaches of the theologian methodologists who followed the Samarqandi sheikhs to become in shadow. Considering this separation within this denomination, when the sunnah sections of usūl al-fiqh literature are compared it is possible to see the different points raised within the Hanafi usūl (...) al-fiqh. In this study, “the definition of sunnah”, “the acts of the Prophet”, “the imitating companions”, “the criteria of ard (submission) to the Qur’an” and “the problem of faqīh (jurist) narrator” are determined as differentiated notions. Considering these issues, since the concepts which differentiate theologian methodologists, whose perception have been taken into account in this paper, from the dominant Hanafi usūl tradition have been generally related to theological concerns, it is possible to argue that this distinction can be explained by their approach of usūl in which theological premises considered as important as other concerns. Eventually, this paper aims to show that like any denomination Hanafi sect also does not have a uniform approach about sunnah.Summary: In this study, the marks of differentiations in sunnah topics were followed based on the works of Ḥanafī usūl al-fiqh written in the Transoxanian region between 5th-8th centuries A.H. The reason for the limitation of this issue is that there have been some changes and developments in the sect in this region and period. It is because Ḥanafī usūl al-fiqh, which is in two different lines, namely ʿIrāqī sheikhs and Samarqandī sheikhs, has improved in favor of one side in this period. It is thought that this dual disintegration occurs due to the effect of different theological tendencies. This situation has caused the different approaches of the theologian methodologists who mostly followed the Samarqandī sheikhs to be overshadowed. Because Ḥanafī tradition, which became a permanent establishment, mostly followed the line of ʿIrāqī sheikhs in terms of both the topics that are discussed and the approaches in these issues. The aim of this study is to determine the different approaches of the line of Samarqandī sheikhs to sunnah. In the study which is based on comparative method, sunnah topics of Dabūsī, Pazdawī, Sarakhsī and those who followed them and the theologian methodologists Abū l-Yusr, Samarqandī, Lamishī and Usmendī’s sunnah topics were compared and the differentiation points of the second group were determined.In this context, it is seen that there are two different approaches in the Ḥanafī usūl al-fiqh regarding the definition and scope of sunnah. Because the Ḥanafī principals who followed the ʿIrāqī sheikhs, while describing the sunnah, they included the companions in the scope of sunnah. However, Abū l-Yusr, Samarqandī and Lamishī did not mention the companions in the sunnah description and stated that the only person to be subjected was the Prophet. In addition, the Ḥanafīs in the second group, unlike others, do not accept the opinion that the meaning of absolute sunnah word is only sunnah of the Prophet. At this point they have shared the same conviction with the ahl al-ḥadīth (the traditionists) and cumhūr al-ulemā (majority of ulema).There are two different approaches, which are based on ʿIrāqī and Samarqandī sheikhs in the show of the judgments of the acts of the Prophet. According to the ʿIrāqī Ḥanafīs, the Prophet's act is attributed to mubāh (permissible) when there is no evidence about its feature. According to the Samarqandī sheiks, such an act is attributed to vucūb (obligation) in terms of practice and stopped in terms of faith. Most of the later Ḥanafī scholars have adopted the idea of ​​ibāha (permissibility) of the ʿIrāqī Ḥanafīs. On the other hand, Samarqandī, Lamishī and Itkanī have tended to the opinion of the Samarqandī sheikhs.It is seen that two different approaches were adopted by Ḥanafī scholars in the field of imitation of companions. Most of the Ḥanafīs adopted the view of Bardaī. According to this view, it is necessary to imitate companions and their expression takes precedence over the qiyās (legal analogy). On the other hand Samarqandī and Lamishī adopted the opinion of Māturīdī. According to this opinion, a companion who has reached the rank of fatwā (legal opinion), it is necessary to imitate that person if one of his peers did not oppose his opinion on a subject that is not likely to be hidden because the general public needs it.There is also a dispute between the Ḥanafī scholars on the type of information expressed by the famous report. Dabūsī, Pazdawī and Sarakhsī and later Ḥanafīs believe that the famous report does not refer to certain knowledge but to assured knowledge. However, it is understood that, Abū l-Yusr, Samarqandī and Lamishī believe that the famous report refers to certain knowledge. But this conflict between the Ḥanafīs only affects the issue of the takfīr who denies the famous report. It does not cause any dispute on judgments.There are two different approaches in the sect about the issue of opposition to the Qur'an covered by internal interruption. In this matter, the issue of opposition to the Qur'an, especially through ziyāda alā al-nās, has been evaluated in different ways. According to the ʿIrāqī sheikhs and majority of the Ḥanafīs, which followed them, ziyada ala al-nas is naskh (abrogation). But according to Māturīdī and Ḥanafīs which followed him, it is also possible that ziyāda alā al-nās is naskh and statement. One of them cannot be preferred without any evidence. In addition, according to the ʿIrāqī sheikhs general and apparent words of the Qur'an express certain knowledge. However, according to the Samarqandī sheikhs the general words of the Qur'an don not express certain knowledge. So, these words can be specialized by isolated tradition. But it was observed that this conflict between the Ḥanafīs was related to the fact that the first opinion caused some problems related to the faith.In the issue of the faqīh narrator, it was determined that three different approaches were exhibited by Ḥanafī scholars. Firstly, the attitude towards not accepting the report of the non-faqih narrator, expressed by the ‘Īsā b. Abān in Abū Hurayra, is gradually being softened along with Dabūsī and adopted by the later Ḥanafī principals. However, despite the same scientific environment and period, Abū l-Yusr does not follow this approach. At the same time, it is possible to say that Samarqandī, Lamishī and Usmendī don not adopt the faqīh narrator criterion. While ‘Abd al-‘Azīz Bukhārī and Kakī did not adopt this approach but criticized it openly. As a result, it is seen that Ḥanafī sect which contains different orientations in itself does not have a uniform approach about sunnah. The points which differentiate theologian methodologists, whose perception have been taken into account in this paper, from the dominant Ḥanafī usūl tradition have been generally related to theological concerns. So, it is possible to say that this distinction can be explained by their approach of usūl in which theological premises considered as important as other concerns. In addition, it is seen that some of the opinions theologian methodologists present as an alternative to dominant Ḥanafī usūl al-fiqh tradition are close to the ahl al-ḥadīth and cumhūr al-ulemā. (shrink)

Species are considered the basic unit of biological classification and evolution. Hence, they are used as a benchmark in several fields, although the ontological status of such a category has always been a matter of debate. This paper aims to discuss the problem of the definition of species within the new mechanistic approach. Nevertheless, the boundary between entities, activities, and mechanisms remains difficult to establish and always requires an analysis of what is meant by explanation. As a case study, the (...) paper describes the debate concerning the species category by considering different kingdoms: Animals, Bacteria, and Fungi. The inherently biological differences between those groups prevent the use of a single, universally applicable concept of species that could fit the mechanisms responsible for the variability present in these kingdoms. The same issue is encountered within each group, as highlighted through a focus on mammals and microbes. This controversy has given rise to opposite approaches, namely: monism, which looks for a single definition that might account for all species, and pluralism, which admits that different groups of organisms require somewhat different definitions. In order to develop an adequate definition of species, we propose to apply a new mechanistic framework, which considers the ontic-epistemic dimensions of scientific explanation in close parallel. The apt correlation between epistemic and the ontic aspects highlights the way in which the concept of species and the reference to data are strictly co-determined. This suggests that the concept of species is better understandable within a dual ontic-epistemic approach. (shrink)

Central to the differentiation and patterning of the Drosophila oocyte is the asymmetric intracellular localization of numerous mRNA and protein molecules involved in developmental signalling. Recent advances have identified some of the molecules mediating oocyte differentiation, specification of the anterior pole of the embryo, and determination of the embryonic germ line. This work is considered in the context of the classical model of the germ plasm as a cytoplasmic determinant for germ cell formation.

Academics have the impression that human nature is good advocate Confucianism, Christianity should make the evil human nature. So when Matteo Ricci and other missionaries to China, agree that people are basically good in the Chinese writings of contemporary scholars do not think that Ricci would have just done for the purpose of mission compromise and will be attached. This article do not support this view. Through on Aquinas' Summa Theologica, "read the relevant chapter and" Mencius "rigorous analysis, I believe (...) that Ricci received" basically good "proposition has its theology support, and closer to Mencius, human nature is good on. However, the era of Matteo Ricci in China is also the era of the popular theory of Wang Yangming. In this article, by a large number of text analysis, pointed out that Wang's human nature is good and Mencius on human nature is good vary widely. Thus, while certainly human nature is good Matteo Ricci, the other critics' re the first, "said, has its theoretical basis. In fact, this return to Mencius Ricci, resist the neo-Confucian practice, is the common position of the Qing Dynasty Han scholars. In this paper, Dai Zhen and Chen Li as an example to illustrate how they both certainly Mencius on human nature is good, but criticized the excessive expansion of human nature is good Song learning theory. Therefore, the Ricci's human nature is good, unexpectedly affected the development of Confucianism in the Qing Dynasty. A large number of contemporary Chinese somehow got the impression that whereas the key tenet of Confucianism is the Thesis of the Innate Goodness of Human Nature, the key tenet of Christianity is the opposite, viz., The Thesis of the Innate Evilness of Human Nature. When Matteo Ricci and his fellow Jesuit missionaries came to China and learnt Chinese culture, Ricci endorses the Thesis of the Innate Goodness of Human Nature in his Chinese book The True Meaning of The Lord of Heaven. Some contemporary Chinese scholars find this endorsement unreasonable and argue that Ricci's endorsement strains the interpretation of Christian doctrine for the appeasement of Confucian literati. This article argues that such contemporary Chinese assessments are based on a misunderstanding of Christian thought. A meticulous reading of relevant sections of Summa Theologiae by Thomas Aquinas shows that there is no conflict between Catholic theological anthropology and the theory of human nature according to Menzi. However, Ricci and his company came to China when the thought of Wang Yangming, one major school of neo-Confucianism, was very influential. Ostensibly Wang also endorses the Innate Goodness of Human Nature, but a careful reading of his works indicates that there is a tremendous difference his thesis and that of Menzi. The latter advocates only that there is a "sprout of goodness" in human nature whereas the former advocates the fill presence of supreme goodness in human nature. Accordingly, it is legitimate for Ricci to endorse the Thesis of the Innate Goodness of Human Nature in the sense of Menzi and simultaneously reject the Thesis of Uncovering the Supreme Goodness in Human Nature of the neo-Confucians. In fact, Ricci's stance of aligning with Menzi in opposition to Song-Ming neo-Confucianism is a common stance of most Qing Confucian scholars. For example, among his fierce criticisms, one of Dai Zhen's critiques is against the neo-Confucian Thesis of Uncovering the Supreme Goodness in Human Nature. He argues that Mengzi's view of "developing the good inclinations" is conducive to the cultivation of virtues whereas neo-Confucians' view of "uncovering our original supreme goodness," misled by Buddhism and Daoism, is not. Very recent historical scholarship in mainland China articulates a view that Dai Zhen has carefully read Ricci's book The True Meaning of The Lord of Heaven and borrows views from it. In fact, according to these historians, Dai Zhen and a closed circle of court scholars who are in charge of compiling the Siku quanshu have read all the works of the Jesuit missionaries and admire their scholarship. Hence the first encounter between Christian civilization and Confucian civilization helped develop the Han School of Learning in opposition to the Song School of Learning in the early Qing Dynasty. (shrink)

Summary While historians have dealt with the origins of the concept of drug receptors in the work of Paul Ehrlich (1854–1915) and John N. Langley (1852–1925) as well as with some of its applications in modern pharmaceutical research, the history of the receptor theory as such has been neglected. Discussing major developments and conceptual changes in receptor theory between about 1910 and 1960 (including relevant contributions by A. V. Hill, A. J. Clark, J. H. Gaddum, E. J. Ariëns and others), (...) this paper attempts to fill this gap in historiography. It provides a case study of the unfolding of research under a new paradigm, but it considers also contemporary criticism and scepticism. By the early 1960s, quantitative investigations of drug action and interpretations of the experimental findings in terms of the receptor concept had become constitutive of the emerging field of ‘molecular pharmacology’. Even then, however, receptors were still hypothetical entities. (shrink)

There is some very limited evidence for a role of estrogens in human psychosexual masculinization; its interpretation is uncertain. Fitch & Denenberg's demonstration of a role for estrogens in the behavioral feminization of nonhuman mammals implicitly suggests an answer to a riddle posed by the syndrome of congenital adrenal hyperplasia in women.

In Primitive Classification, Durkheim suggests using the notion of affectivity to explain the emergence of various social structures. This bold attempt to extend the role of affectivity in sociological thinking has been rejected by most social scientists. By greatly elaborating Durkheim's outline for a sociology of emotions, however, this essay suggests that there is a fruitful way to use affectivity in macrosociological theory. This model allows us to develop in a new way Durkheim's description of structural differentiation and stratification (...) in The Division of Labor in Society. (shrink)

The “community effect” is necessary for tissue differentiation. In the Xenopus muscle paradigm, e‐FGF has been identified as a candidate community factor. Standley et al.1 now show that the community effect, mediated through FGF signalling, continues to be important at later stages of development in the posterior part of the embryo. In this region, the paraxial mesoderm is still undergoing segmentation into somites, which are the site of early skeletal muscle formation. Indeed, somitogenesis, together with the read‐out of the (...) Hox code, which confers anteroposterior positional identity, is regulated by FGF signalling. This raises the question of the co‐ordination between these events and the community effect which orchestrates myogenesis. BioEssays 25:13–16, 2003. © 2002 Wiley Periodicals, Inc. (shrink)

On the basis of the evidence that tumor development is suppressed by the embryonic microenvironment, some experiments using the factors taken from Zebrafish embryo at precise stages of cell differentiation were made. These experiments demonstrated a significant growth inhibition on different tumor cell lines in vitro. The observed mechanism of tumor growth inhibition is connected with the key-role cell cycle regulation molecules, such as p53 and pRb, which are modified by transcriptional or post-translational processes. Research on apoptosis and (...) class='Hi'>differentiation revealed that treatment with these factors induces caspase-3 with a p73 apoptotic-dependent pathway activation and a concurrent significant normalization of e-cadherin and beta-catenin ratio. Other experiments found a synergistic effect on the colon cancer proliferation curve after the concurrent treatment with these factors and 5-fluorouracil. Finally, a product prepared for human therapy demonstrated 19.8% regression and 16% stable disease in an... (shrink)

There are many obvious morphological and behavioural differences between male and female Drosophila, whose differing phenotypes are produced by a hierarchy of sex determination genes. These genes have been well characterised at the genetic and molecular level. Similarly, a number of sex‐specific differentiation genes have been characterised, such as the chorion and vitelline membrane genes in females and the sex peptide and other accessory gland proteins in males. Despite the depth of these parallel studies, there is only one example (...) of a direct link between the sex determination pathway and the downstream sex differentiation genes, namely the regulation of the female‐specific yolk protein genes. The yolk proteins are synthesised in the fat body and ovarian follicle cells of the adult female and are subsequently transported to the oocyte where they are stored for utilization during embrygenesis. The expression of the yolk protein genes is not entirely controlled by the sex determination hierarchy, as several different regulatory pathways must interact to direct their correct sexual, temporal and spatial regulation during development. (shrink)

On the basis of research in the social identity tradition, we contend (a) that identification and differentiation are not mutually exclusive, (b) that a sequence in which identification gives way to differentiation is not necessarily associated with superior organizational outcomes, and (c) that social identification, and leadership that builds this, is generally a prerequisite for group success.

The ascidian embryo has long provided a model system for ‘mosaic’ development. This article reviews recent advances in the study of ascidian developmental biology. These include: (a) the re‐analysis of cell lineages in ascidian embryos with the ascertainment of developmental fates of every blastomere of a 110‐cell embryo; (b) the development of several tissue‐specific monoclonal antibodies; (c) the investigation and description of cell cycle requirements for differentiation; it has been found that neither cytokinesis nor nuclear division is required for (...) differentiation, but that several rounds of DNA replication are essential for the expression of certain tissue‐specific genes; and (d) the demonstration by new descriptive and experimental studies of the presence of cytoplasmic factors or determinants responsible for specification of embryonic cell features; myoplasm which is thought to contain muscle determinants has been isolated, and immunological attempts to elucidate the molecular nature of the factors have begun. (shrink)

Embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) can self‐renew indefinitely and contribute to all tissue types of the adult organism. Stem cell‐based therapeutic approaches hold enormous promise for the cure of regenerative diseases. Over the last few years, several studies have attempted to decipher the important role of transcription factor networks and epigenetic regulatory signals in the maintenance of ESC pluripotency, but the exact underlying mechanisms have yet to be identified. Among the epigenetic factors, chromatin dynamics and (...) structure have been found to contribute greatly to maintenance of pluripotency and regulation of differentiation in ESCs. These modifications include: covalent histone acetylation and methylation, histone bivalents and chromatin remodeling, and DNA methylation. Studies in ESCs have shown that genes associated with early development are arranged within a bivalent chromatin structure. This is thought to be a “poised yet repressed” situation, which can be activated upon differentiation. The breakthrough of iPSCs has opened a new era in stem cell biology. During reprogramming, the chromatin state of differentiated cells is reset to an embryonic form via a largely unknown mechanism. In this review, the fundamental impact of chromatin dynamic in ESCs as well as its critical role in the generation of iPSCs is discussed. (shrink)

The neural crest is a transient population of multipotent progenitors arising at the lateral edge of the neural plate in vertebrate embryos. After delamination and migration from the neuroepithelium, these cells contribute to a diverse array of tissues including neurons, smooth muscle, craniofacial cartilage, bone cells, endocrine cells and pigment cells. Considerable progress in recent years has furthered our understanding at a molecular level of how this important group of cells is generated and how they are assigned to specific lineages. (...) Here we review a number of recent studies supporting a role for Wnt signaling in neural crest induction, differentiation, and apoptosis. We also summarize the timing of expression of a number of Wnt ligands and receptors with respect to neural crest induction. BioEssays 25:317–325, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

Many lymphokine genes have now been cloned from activated T cells and their products have been expressed in mammalian cells. Use of these recombinant lymphokines has provided the opportunity to evaluate both the spectrum of their biological activities and the mechanisms of their action in promoting proliferation and differentiation of hemopoietic and lymphoid cells. Characterization of the structure of lymphokine genes will provide information about their regulated expression in T‐cell activation.

This review explores the hypothesis that regulation of nucleocytoplasmic shuttling is a means of driving differentiation, using spermatogenesis as a model. The transition from undifferentiated spermatogonial stem cell to terminally differentiated spermatozoon is, at its most basic, a change in the repertoire of expressed genes. To effect this, the complement of nuclear proteins, such as transcription factors and chromatin remodelling components must change. Current knowledge of the nuclear proteins and nucleocytoplasmic transport machinery relevant to spermatogenesis is consolidated in this (...) review, and their functional linkages are highlighted not only as a means of regulating nuclear protein composition, but also as a key mechanism regulating gene transcription and hence cell fate. Through this, we hypothesize that male germ cell differentiation is mediated through regulation of nuclear transport machinery components, and thereby of the access of critical factors to the nucleus. The importance of nucleocytoplasmic trafficking to male germ cell differentiation is discussed, using the sex-determining factors Sry and SOX9, cell cycle regulators, CREM and cofactors and the Smads as specific examples, together with the roles in gametogenesis for particular nuclear transport factors in Caenorhabditis elegans and Drosophila. BioEssays 27:1011–1025, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

Our research focuses on the perception of difference in the evaluations of positive and negative options. The literature provides evidence for two opposite effects: on the one hand, negative objects are said to be more differentiated, on the other, people are shown to see greater differences between positive options. In our study, we investigated the perception of difference between fictitious political candidates, hypothesizing greater differences among the evaluations of favorable candidates. Additionally, we analyzed how positive and negative information affect candidate (...) evaluation, predicting further asymmetries. In three experiments, participants evaluated various candidate profiles presented in a numeric and narrative manner. The evaluation tasks were designed as individual or joint assessments. In all three studies, we found more differentiation between positive than negative options. Our research suggests that after exceeding a certain, relatively small level of negativity, people do not see any further increase in negativity. The increase in positivity, on the other hand, is more gradual, with greater differentiation among positive options. Our findings are discussed in light of cognitive-experiential self-theory and density hypothesis. (shrink)