Online research in philosophy

It is often argued that development aid can and should compensate the restrictions on migration. Such compensation, Shachar has recently argued, should be levied as a tax on citizenship to further the global equality of opportunity. Since citizenship is essentially a ‘birthright lottery’, that is, a way of legalizing privileges obtained by birth, it would be fair to compensate the resulting gap in opportunities available to children born in rich versus poor countries by a ‘birthright privilege levy’. This article (...) sets out a defence of three theses. The first states that equality of opportunity is incompatible with, and cannot be achieved in, segregated territories. The second posits that to believe that material equality compensates the injustice of restrictions on movement is to commit a ‘sedentarist mistake’. The third affirms that any citizenship levy, including the egalitarian and non-sedentarist formula I’m proposing, would be better understood as a penalty rather than a tax. (shrink)

Brain drain critiques and human rights advocates have conflicting views on emigration. From a brain drain perspective, the emigration harms a country when emigrants are skilled and the source country is poor. From the human rights perspective, the right "to leave any country, including one's own" is a fundamental right, protected for all, whatever their skills. Is the concern with poverty and social justice at odds with the right to emigrate? At the beginning of the l970s, the economist Jagdish Bhagwati (...) replied in the negative. He imagined a tax on the income earned by the skilled migrants in the destination country, to the benefit of the source country. He thus sought to reconcile the right to emigration and the brain drain effects. -/- This article argues that there is no need to tax skilled migrants in order to reconcile the right to emigration and social justice. Social justice is not incompatible with the right to emigration but rather with restrictions on mobility. If it is both the case that equal opportunities are a minimal requisite for social justice, and that access to opportunities implies freedom of movement, as I shall argue, then the brain drain criticism doesn't satisfy the minimal requirements of social justice. -/- The article is divided into three parts. Each part rejects one of the possible justifications of the Bhagwati tax, that is, as a way, for skilled migrants, (i.) to compensate the welfare loss occasioned to their country of origin; (ii.) to discharge for their obligation to the national community when it publicly financed their education; and (iii.) to compensate for the resulting inequality of opportunities between themselves and their non-migrant compatriots. (shrink)

The assumption that human socializing instincts are restricted to the community of birth and upbringing was long accepted without question. But today’s modern states have passed from the nation-building stage into that of multicultural belonging, and fluidity of membership allied to perpetual population shifts is the norm. This article traces changing patterns of global migration: first, territoriality plus rooted identity plus ‘gardening’; second, emigration to supposedly ‘empty’ lands; third, interlocked diasporas. How may we now live with and in the (...) right to difference? Identity formation is never fixed, never final, veering between the pole of freedom and that of security. It is an intertwining of continuity and discontinuity that may now hold society together. (shrink)

Calls to expand temporary work programmes come from two directions. First, as global justice advocates observe, every year thousands of poor migrants cross borders in search of better opportunities, often in the form of improved employment opportunities. As a result, international organizations now lobby in favour of expanding ‘guest-work’ opportunities, that is, opportunities for citizens of poorer countries to migrate temporarily to wealthier countries to fill labour shortages. Second, temporary work programmes permit domestic governments to respond to two internal, contradictory (...) political pressures: (1) to fill labour shortages and (2) to do so without increasing rates of permanent migration. Temporary work programmes permit governments to appear ‘tough’ on migration, while responding to employer pressure to locate workers willing to work in low-skilled, poorly remunerated positions. The coincidence of national self-interest and global justice generates a strong case in favour of expanding guest-work. We evaluate the moral benefits and burdens of expanding guest-work opportunities, and conclude that although there are benefits to be gleaned from the perspective of global wealth redistribution, at present, temporary work programmes are generally unjust. We will argue that just temporary work programmes, in time, permit temporary workers to attain citizenship. This spells the end of traditional temporary work programmes, which require that workers return to their home country in time; instead, what is temporary is the employment obligation that must be fulfilled as a requirement to access citizenship. As long as this requirement is met, we endorse guest-work programmes as a tool to respond to global inequality. (shrink)

Popper's thesis that the growth of knowledge lies in the emergence of problems out of criticism and takes place in an autonomous world of products of the human mind (his so-called world-3) raises two questions: (1) Why does criticism lead to new problems, and (2) Why can only a limited number of tentative solutions arise at a given time? I propose the following answer: Criticism entails an overlooked evolutionary world-3 mechanism, namely, the migration of piece meal conceptual schemes from (...) one research tradition to another. Popper by passed the questions above because he relied very heavily on the selective power of criticism. (shrink)

The intensified nurse migration leads to severe problems for the health care systems in many developing countries. Using the Philippines as an example, this paper will address the question of global nurse migration from a philosophical perspective. John Rawls' liberal and Michael Walzer's communitarian theory of justice will be examined in view of the ethical problem of nurse migration. In line with Rawls' A Theory of Justice, nurse migration undermines the ability of the people in developing (...) countries to make use of their basic rights and liberties. Walzer's communitarian assessment of nurse migration, on the other hand, will stress the shared ‘thin’ morality, as well as the shared history between the ‘donating’ and receiving countries. This paper argues that the commonality of a shared history and common values implies the moral obligation to ensure a fairer distribution of nurses. (shrink)

Many nations in the developing world invest scarce funding into training health workers. When these workers migrate to richer countries, particularly when this migration occurs before the source community can recoup the costs of training, the destination community realizes a net gain in resources by obtaining the workers' skills without having to pay for their training. This effect of health worker migration has frequently been condemned as 'poaching' or a case of theft. I assess the charge that the (...) rich nations of the world poach the resources of the developing world through the active recruitment of migrants. I argue that the charge of poaching is misguided in these cases. The misuse of the term poaching is particularly troubling as it distracts attention away from the many actual moral wrongs taking place through the process of health worker migration and objectifies health workers. (shrink)

Department of Philosophy and Center for Health Policy, Research and Ethics, George Mason University, 4400 University Avenue, MS 2D7, Fairfax, VA 22030, USA. Tel.: +1 703 993 1724; Fax: +1 5703 993 1555; Email: leckenwi{at}gmu.edu ' + u + '@' + d + ' '//--> . Abstract Here I consider the migration of health workers and propose a conception of transnational justice that can best address the concerns it raises, including the perpetuation of global health inequities. My focus will (...) be on nurses and direct care workers (DCWs), also called paraprofessionals—the vast majority of whom are women—coming from the global South to the United States. In the first part of the paper I will identify the factors behind this flow of what I will hereafter call ‘care workers’. From there, I will describe a conception of transnational justice that seems especially promising and explore selected policy options. Finally, I will conclude by offering specific prescriptions for action on the part of a wide range of agents, including institutions as well as individuals. CiteULike Connotea Del.icio.us What's this? (shrink)

While the control of cell migration by biochemical and biophysical factors is largely documented, a precise quantification of cell migration parameters in different experimental contexts is still questionable. Indeed, these phenomenological parameters can be evaluated from data obtained either at the cell population level or at the individual cell level. However, the range within which both characterizations of cell migration are equivalent remains unclear. We analyse here to which extent both sources of data could be integrated within (...) a unified description of cell migration by considering the motility of the endothelial cell line EAhy926. Using time-lapse video-microscopy and associated analysis of digital image time series, we quantified EAhy926 random motility coefficient, migration speed and trajectory persistence time in two different migration assays: the in vitro wound healing assay, and the cell-populated agarose drop assay. In order to analyse the agreement between independent quantifications of cell motility based either on individual cell analysis or cell population dynamic analysis, a theoretical multi-agents cellular model was developed and discussed as a possible theoretical framework able to unify these multi-scale data. Model simulations especially reveal the potential bias induced by cell proliferation and cell-cell adhesion when cell migration parameters are estimated from the extensively used in vitro wound healing assay. (shrink)

Human migration is nonrandom. In small scale societies of the past, and in the modern world, people tend to move to wealthier, safer, and more just societies from poorer, more violent, less just societies. If immigrants are assimilated, such nonrandom migration can increase the occurrence of culturally transmitted beliefs, values, and institutions that cause societies to be attractive to immigrants. Here we describe and analyze a simple model of this process. This model suggests that long run outcomes depend (...) on the relative strength of migration and local adaptation. When local adaption is strong enough to preserve cultural variation among groups, cultural variants that make societies attractive always predominate, but never drive alternative variants to extinction. When migration predominates, outcomes depend both on the relative attractiveness of alternative variants and on the initial sizes of societies that provide and receive immigrants. (shrink)

In a theological understanding of nature, what is the significance of herons? This article reflects on the question of herons by first describing how bird migration can be included in a theological approach to nature. To explore the theological meaning of migration, theology must model nature as defined by the idea of 'emplacement'. Next, it investigates how the migration of herons challenges and complements our sense of dwelling by detailing the different ways that herons are emplaced as (...) migratory birds. It concludes by offering three insights into the place of herons in a philosophical theology of nature. First, migrating herons and other non-human animals penetrate into nature as both radically particular creatures and anonymously general ones. Second, herons push us to understand the theological meaning of the otherness of Otherness. Third, non-human animals remind us to move beyond solipsistic views of our emplacement. Together with a general description of the elements of emplacement that are added by the migration of herons, we see how we are theologically influenced by the 'intimate distance' of herons. (shrink)

The grounds for global solidarity have been theorized and conceptualized in recent years, and many have argued that we need a global concept of solidarity. But the question remains: what can motivate efforts of the international community and nation-states? Our focus is the grounding of solidarity with respect to global inequities in health. We explore what considerations could motivate acts of global solidarity in the specific context of health migration, and sketch briefly what form this kind of solidarity could (...) take. First, we argue that the only plausible conceptualization of persons highlights their interdependence. We draw upon a conception of persons as ‘ecological subjects’ and from there illustrate what such a conception implies with the example of nurses migrating from low and middle-income countries to more affluent ones. Next, we address potential critics who might counter any such understanding of current international politics with a reference to real-politik and the insights of realist international political theory. We argue that national governments – while not always or even often motivated by moral reasons alone – may nevertheless be motivated to acts of global solidarity by prudential arguments. Solidarity then need not be, as many argue, a function of charitable inclination, or emergent from an acknowledgment of injustice suffered, but may in fact serve national and transnational interests. We conclude on a positive note: global solidarity may be conceptualized to helpfully address global health inequity, to the extent that personal and transnational interdependence are enough to motivate national governments into action. (shrink)

I would like to thank all of the respondents to my article both for their expansions on the theme of health worker migration and for their criticisms of my argument against the use of the term ’poaching’ in the context of international health worker migration. In this response, I will clarify my argument in light of the worries raised primarily by Tache and Schillinger and Ari Zivotofsky and Naomi Zivotofsky.

We consider a two-patch epidemiological system where individuals can move from one patch to another, and local interactions between the individuals within a patch are governed by the classical SIRS model. When the time-scale associated with migration is much smaller than the time-scale associated with infection, aggregation methods can be used to simplify the initial complete model formulated as a system of ordinary differential equations. Analysis of the aggregated model then shows that the two-patch basic reproduction rate is smaller (...) than the 1 patch one. We extend this result to a linear chain of P patches (P > 2). These results are illustrated by some examples for which numerical integration of the system of ordinary differential equations is performed. Simulations of an individual based model implemented with a multi-agent system are also carried out. (shrink)

As cultural evolutionists interested in how culture changes over the long term, we've thought and written a lot about migration, but only recently tumbled to an obvious idea: migration has a profound effect on how societies evolve culturally because it is selective. People move to societies that provide a more attractive way of life, and all other things being equal, this process spreads ideas and institutions that lead to economic efficiency, social order and equality.

This paper argues that in liberal nations migration law orders chaotic images and is an important site for the construction of national identities. Empirical illustrations are drawn primarily from Australia, but the thesis is applicable to all immigrant nations and also provides insights for the “Old World”. The argument proceeds by first examining the role of migration laws in liberal democratic societies. Building on this framework, it then looks at how Australian migration law responds to images of (...) disorder outside the nation. Finally, it considers how migration law addresses disorder within the nation by reflecting a coherent picture of Australian national identity. (shrink)

There are few issues more urgently in need of intelligent analysis both in the UK and elsewhere than those relating to displacement, asylum, and migration. In this volume, based on the 2004 Oxford Amnesty Lectures, major figures in philosophy, political science, law, psychoanalysis, sociology, and literature address the challenges that displacement, asylum, and migration pose to our notions of human rights. Each lecture is accompanied by a critical response from another leading thinker in the field. -/- The volume (...) contains lectures by Slavoj Zizek, Bhikhu Parekh, Ali A.Mazrui, Matthew J. Gibney, Saskia Sassen, Harold Hongju Koh, Caryl Phillips, and Jacqueline Rose, with critical responses from Michael Ignatieff, Seyla Benhabib, Iftikhar Malik, Melissa Lane, Christian Joppke, Rey Koslowski, Elleke Boehmer, and Ali Abunimah. -/- This is the twelfth volume of Oxford Amnesty Lectures to be published since 1992. -/- 'All good citizens should probably want to buy them . . . simply because they are published in support of such a good cause. It turns out, though, that no self-sacrifice is involved. [These] are immensely rich, challenging, stimulating volumes . . . The contributors' lists are star-studded . . . and each book has a clear, coherent, overarching theme, despite the extreme diversity of the individual lectures' (The Independent, April 10, 2003). (shrink)

The article discusses a particularly contentious aspect of labour mobility—state sanctioned and controlled temporary labour migration. In contrast to forced migration, which always has had a recognizable ethical dimension in terms of the universal right to asylum, temporary labour migration has tended to be viewed as an exclusively economic and thus ethically neutral phenomenon. This article presents a diametrically opposite approach to temporary labour migration: it is argued that this form of labour mobility creates a plethora (...) of ethical challenges to the body which regulates it—the state. Furthermore, attention is drawn to employers’ rationalizations in relation to temporary migrant workers and trade unions’ responses to it. The article examines how these industrial relations actors deal with the moral hazards characteristic to temporary labour migration. It concludes with the exploration of the emergent issues in migration ethics and points out to a tentative research agenda. (shrink)

Latinos comprise the largest minority group in the U.S. and 63 percent are foreign-born. An educational gap exists between Latinos in the U.S. and other groups in the U.S. Lower educational attainment has ramifications for labor market and other socioeconomic outcomes. Factors involving family context have best explained the educational gap, along with English proficiency and migration history. This study, using the Census long-form data, explores the role of socio-economic background, ethnicity, and migration history on educational outcomes of (...) Latinos in the Midwest, an area that is experiencing recent growth in its Latino population. Results indicate that these factors do impinge negatively on academic achievement of Latino and Non-Hispanic black youth. In order to be more effective in alleviating the achievement gap, multicultural education must not only incorporate culture and inclusion, but also a true understanding of the factors and circumstances that impact youth achievement and how these impact achievement. (shrink)

The notion of a migration system is often invoked but it is rarely clearly defined or conceptualized. De Haas recently provided a powerful critique of the current literature highlighting some important flaws that recur through it. In particular, migration systems tend to be identified as fully formed entities, and there is no theorization as to how they come into being and how they break down. The internal dynamics which drive such changes are not examined. Such critiques of (...) class='Hi'>migration systems relate to wider critiques of the concept of systems in the broader social science literature, where they are often presented as black boxes in which human agency is largely excluded. The challenge is how to theorize system dynamics in which the actions of people at one time contribute to the emergence of systemic linkages at a later time. This article focuses on the genesis of migration systems and the notion of pioneer migration. It draws attention both to the role of particular individuals, the pioneers, and also the more general activity of pioneering which is undertaken by many migrants. By disentangling different aspects of agency, it is possible to develop hypotheses about how the emergence of migrations systems is related to the nature of the agency exercised by different pioneers or pioneering activities in different contexts. Content Type Journal Article Category Article Pages 413-437 DOI 10.1558/jcr.v11i4.413 Authors Oliver Bakewell, International Migration Institute, University of Oxford Hein De Haas, International Migration Institute, University of Oxford Agnieszka Kubal, International Migration Institute, University of Oxford Journal Journal of Critical Realism Online ISSN 1572-5138 Print ISSN 1476-7430 Journal Volume Volume 11 Journal Issue Volume 11, Number 4 / 2012. (shrink)

Human migration is nonrandom. In small scale societies of the past, and in the modern world, people tend to move to wealthier, safer, and more just societies from poorer, more violent, less just societies. If immigrants are assimilated, such nonrandom migration can increase the occurrence of culturally transmitted beliefs, values, and institutions that cause societies to be attractive to immigrants. Here we describe and analyze a simple model of this process. This model suggests that long run outcomes depend (...) on the relative strength of migration and local adaptation. When local adaption is strong enough to preserve cultural variation among groups, cultural variants that make societies attractive always predominate, but never drive alternative variants to extinction. When migration predominates, outcomes depend both on the relative attractiveness of alError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapError: Illegal entry in bfrange block in ToUnicode CMapternative variants and on the initial sizes of societies that provide and receive immigrants. (shrink)

Highly malignant neuroepithelial tumors are known for their extensive tissue invasion. Investigating the relationship between their spatial behavior and temporal patterns by employing detrended fluctuation analysis (DFA), we report here that faster glioma cell motility is accompanied by both greater predictability of the cells' migration velocity and concomitantly, more directionality in the cells' migration paths. Implications of this finding for both experimental and clinical cancer research are discussed.

In this work we study the behavior of a time discrete multiregional stochastic model for a population structured in age classes and spread out in different spatial patches between which individuals can migrate. The dynamics of the population is controlled both by reproduction-survival and by migration. These processes take place at different time scales in the sense of the latter being much faster than the former. We incorporate the effect of demographic stochasticity into the population, which results in both (...) dynamics being modelled by multitype Bienaymé–Galton–Watson branching processes. We present a multitype global model that incorporates the effect of both processes and, making use of the existence of different time scales for demography and migration, build a reduced model in which the variables correspond to the total population in each age class. We extend previous results that relate the behavior of the original and the reduced model showing that, given a large enough separation of time scales between demography and migration, we can obtain information about the behavior of the multitype global model through the study of the simpler reduced model. We concentrate on the case where the two systems are supercritical and therefore the expected number of individuals grows to infinity, and show that we can approximate the asymptotic structure of the population vector and the asymptotic population size of the original system through the study of the reduced model. (shrink)

Christine Straehle | : Qui peut revendiquer un territoire, sur quelles bases et avec quelles conséquences sont des questions qui font l’objet de débats en philosophie politique contemporaine. En réponse, j’adopte « la théorie de l’État légitime » proposée par Stilz. Selon Wellman, une conséquence des revendications territoriales serait le droit de l’État de refuser la migration sur son territoire. Je juxtapose son propos de l’État légitime avec celui de Stilz et soutiens que, si l’on accepte la fondation de (...) l’État légitime sur la valeur de l’autonomie individuelle, accepter seulement des devoirs négatifs, soit de ne pas violer les droits des non-citoyens, n’est pas plausible. Je justifie les devoirs positifs des États légitimes d’aider à la réalisation de l’autonomie individuelle pour tous ceux dont les États d’origine échouent à la tâche et qui souhaitent se joindre et soutenir les institutions de l’État légitime. Cela implique l’obligation de l’État de permettre leur immigration. | : Who can claim a territory, on what grounds and what such claims entitle to has recently been the subject of much philosophical debate. In answer to this question, I adopt the ‘legitimate state theory’ proposed by Stilz. One consequence of the claim to territory that has been proposed by Wellman is the right to refuse migration onto a territory. I contrast his and Stilz’ account of the legitimate state and argue that if we accept that legitimate states are grounded on the value of individual autonomy, it is not plausible why states only have the negative duty to not violate human rights in dealings with non-citizens ; instead, I argue that states have positive duties to realize the possibility for individual autonomy for all those whose states fail in providing them with the means to individual autonomy and who wish to join and support the institutions of the legitimate state. This implies a duty to allow their immigration. (shrink)

: When health care workers migrate from poor countries to rich countries, they are exercising an important human right and helping rich countries fulfill obligations of social justice. They are also, however, creating problems of social justice in the countries they leave. Solving these problems requires balancing social needs against individual rights and studying the relationship of social justice to international justice.

A key dividing line in the literature on post-national citizenship concerns the role of collective identity. While some hold that a post-national form of identity is desirable in developing citizenship in contexts such as the European Union (EU), others question the defensibility of a collective identity at this supra-national level. The aim of this article is to intervene in this debate, drawing on qualitative research to consider the extent to which post-national citizenship should be accompanied by a form of post-national (...) identity. The article takes the UK as a case study, and explores tensions between the immigration policies and rhetoric of the Coalition Government since 2010 and the post-national citizenship rights of EU citizens migrating into British local communities. It draws on independently collected qualitative data from the county of Herefordshire, UK, to argue that the persistent reinforcement of national identity reproduces national lines of difference which further problematise the full realisation of European citizenship. At a theoretical level, this highlights the need for the development of post-national citizenship rights to be accompanied by a paradigmatic shift in the way that collective identity is constituted in post-national contexts. (shrink)

Little work has been done to explore the moral foundations of the state’s right to territory.1 In modern times, the state has mostly been assumed to be a territorial unit, and no need was perceived to reflect on precisely what justifies its territorial jurisdiction. The state’s territoriality is related to another topic that has remained under-theorized: immigration. There is, moreover, an obvious relationship between these topics: the more powerful a state’s rights over its territory, the more powerful the right to (...) constrain access to that territory might become – or so, at any rate, we might suppose. Rights to territory and rights to immigration are usefully theorized together.2 Our starting point is a Lockean analysis of the moral foundations of territoriality offered by Simmons (2001). This is a natural starting point not only because Simmons is one of the very few contemporary writers who have taken up philosophical questions about territoriality in the first place, but also because Locke’s thought, as Simmons makes clear, actually allows for the development of a sophisticated account of territoriality. This makes Locke stand out simply because generally modern political.. (shrink)

Does humanity have a moral obligation toward the estimated millions of individuals who will be displaced from their homes over the course of this century primarily due to sea-level rise as the Earth’s climate warms? If there are indeed sound reasons for the world to act on their behalf, what form should these actions take? -/- This paper argues that migration and permanent resettlement would be the only possible “adaptation” strategy available to millions. While existing international law provides no (...) solution for these individuals, the only just remedy is in the form of special rights of free global movement and resettlement in regions and countries on higher ground in advance of disaster. (shrink)

Hannah Arendt argued that refugees pose a major problem for liberalism. Most liberal theorists endorse the idea of human rights. At the same time, liberalism takes the existence of sovereign states for granted. When large numbers of people petition a liberal state for asylum, Arendt argued, these two commitments will come into conflict. An unwavering respect for human rights would mean that no refugee is ever turned away. Being sovereign, however, allows states to control their borders. States supposedly committed to (...) human rights will thus often violate the rights of refugees by denying them entry. I attempt to defend liberalism from Arendt’s criticism by outlining a rights-based model of asylum that is enforceable by sovereign states. This approach avoids the question of what border-enforcement measures, if any, are defensible at the level of ideal justice, and instead seeks to outline a framework of refugee rights that can be realized in a world in which migration controls are a fact of life. Central to my argument is a distinction between the place where a person is recognized as a rights-bearing agent and the potentially different place where he or she exercises those rights. (shrink)

It is often claimed that states enjoy, as a consequence of their sovereign status, the right to control the passage of outsiders through their territory and that they have a discretion to admit or to refuse to admit outsiders, whether those outsiders be tourists, business travelers, would-be economic migrants, or even refugees. Or, to be more exact, such limitations on that right to control are derived from the agreement of states to treaties and conventions, agreement which they could have withheld (...) and could yet revoke. As a statement of the legal position this is not completely uncontroversial,1 but my aim in this paper is not to make a contribution to international law or law at all. Rather, my concern is with political philosophy and with the issue of whether.. (shrink)

Most observers of the Chinese consumer market have seen its linear evolution from a traditional culture toward a more Westernized consumer society during the country's three-decade experimentation of the free market. Recent development, however, shows a cultural renaissance in China wherein Chinese people have increasingly demanded their traditional culture components to be part of their consumption experience, coinciding with China's re-emergence as a country of economic and political power. We identify this shift, explore its causes, and discuss its managerial and (...) theoretical implications. (shrink)

Mathematical models of tumour invasion appear as interesting tools for connecting the information extracted from medical imaging techniques and the large amount of data collected at the cellular and molecular levels. Most of the recent studies have used stochastic models of cell translocation for the comparison of computer simulations with histological solid tumour sections in order to discriminate and characterise expansive growth and active cell movements during host tissue invasion. This paper describes how a deterministic approach based on reaction-diffusion models (...) and their generalisation in the mechano-chemical framework developed in the study of biological morphogenesis can be an alternative for analysing tumour morphological patterns. We support these considerations by reviewing two studies. In the first example, successful comparison of simulated brain tumour growth with a time sequence of computerised tomography (CT) scans leads to a quantification of the clinical parameters describing the invasion process and the therapy. The second example considers minimal hypotheses relating cell motility and cell traction forces. Using this model, we can simulate the bifurcation from an homogeneous distribution of cells at the tumour surface toward a nonhomogeneous density pattern which could characterise a pre-invasive stage at the tumour-host tissue interface. (shrink)

Our main thesis is that the U.S. has a duty of justice to adopt an open-border policy with regard to economic migrants because it is significantly responsible for the unjust social and economic conditions that bring such migrants to its borders. From this perspective, President Bush’s recent “guest worker” proposal is morally objectionable because it is designed more to serve U.S. business interests than the interests of the migrants. We address three objections to opening borders: it will worsen the economic (...) condition especially of low-skilled native workers; it will harm developing countries by increasing the so-called “brain drain”; and it is preferable to discharge our responsibility to the global poor by increasing development assistance instead of adopting an open-border policy. (shrink)

The American Journal of Bioethics, Volume 12, Issue 9, Page 11-13, September 2012.

TRYING to trace the ancient roots of a modern language is always a maddeningly ambiguous and uncertain enterprise. With Yiddish, the language of the Ashkenazic Jews of Central and Eastern Europe, the task is even harder because of the horrifying fact that most of the speakers were exterminated in the Holocaust.

Background Traditional top-down national regulation of internationally mobile doctors and nurses is fast being rendered obsolete by the speed of globalisation and digitisation. Here we propose a bottom-up system in which responsibility for hiring and accrediting overseas staff begins to be shared by medical employers, managers, and insurers. Discussion In this model, professional Boards would retain authority for disciplinary proceedings in response to local complaints, but would lose their present power of veto over foreign practitioners recruited by employers who have (...) independently evaluated and approved such candidates' ability. Evaluations of this kind could be facilitated by globally accessible National Registers of professional work and conduct. A decentralised system of this kind could also dispense with time-consuming national oversight of continuing professional education and license revalidation, which tasks could be replaced over time by tighter institutional audit supported by stronger powers to terminate underperforming employees. Summary Market forces based on the reputation (and, hence, financial and political viability) of employers and institutions could continue to ensure patient safety in the future, while at the same time improving both national system efficiency and international professional mobility. (shrink)

We study the effects of density dependent migrations on the stability of a predator-prey model in a patchy environment which is composed with two sites connected by migration. The two patches are different. On the first patch, preys can find resource but can be captured by predators. The second patch is a refuge for the prey and thus predators do not have access to this patch. We assume a repulsive effect of predator on prey on the resource patch. Therefore, (...) when the predator density is large on that patch, preys are more likely to leave it to return to the refuge. We consider two models. In the first model, preys leave the refuge to go to the resource patch at constant migration rates. In the second model, preys are assumed to be in competition for the resource and leave the refuge to the resource patch according to the prey density. We assume two different time scales, a fast time scale for migration and a slow time scale for population growth, mortality and predation. We take advantage of the two time scales to apply aggregation of variables methods and to obtain a reduced model governing the total prey and predator densities. In the case of the first model, we show that the repulsive effect of predator on prey has a stabilizing effect on the predator-prey community. In the case of the second model, we show that there exists a window for the prey proportion on the resource patch to ensure stability. (shrink)

Brain drain, the migration of skilled labor out of less-developed countries, is an especially acute problem in the medical sector. Countries in the global South face enormous shortages of health-care workers. The most direct solution, to train more doctors and nurses, does not solve the problem because so many of those who are trained move to the global North to take advantage of higher salaries and an improved standard of living. Because we live in a world with porous boundaries (...) and integrated economies, it is incumbent on us to think through questions that arise because of structural factors that benefit the already wealthy and developed economies at the expense of impoverished and struggling economies. Medical .. (shrink)

We examine the consequences of long-range effects on tumour cell migration. Our starting point are previous results of ours where we have shown that the migration patterns of glioma cells are best interpreted if one assumes attractive interactions between cells. Here we complement the cellular automaton model previously introduced by the assumption of the existence of a chemorepellent produced by the main bulk of large spheroids (in the hypoxic/necrotic areas). Visible effects due to the presence of such a (...) substance can be found in the density profiles of cells migrating out of a single spheroid as well as in the angular distribution of cells coming from two close-lying spheroids. These effects depend crucially on the diffusion speed of the chemorepellent. A comparison of the simulation results to experimental data of Werbowetski et al. allows to draw (tentative) conclusions on the existence of a chemorepellent and its properties. (shrink)

This article improves our understanding of the reasons underlying the intellectual migration of scientists from existing cognitive domains to nascent scientific fields. To that purpose we present, first, a number of findings from the sociology of science that give different insights about scientific migration. We then attempt to bring some of these insights together under the conceptual roof of an actor-based approach linking expected utility and diffusion theory. Intellectual migration is seen as the choice of scientists who (...) decide under uncertainty and on the base of estimations about probabilities, costs, and benefits of the migration. The resulting choice model can be used as a heuristic base for further exploration of the subject. (shrink)