2,537 research outputs found
Feasibility study for the Cryogenic Orbital Nitrogen Experiment (CONE)
An improved understanding of low gravity subcritical cryogenic fluid behavior is critical for the continued development of space based systems. Although early experimental programs provided some fundamental understanding of zero gravity cryogenic fluid behavior, more extensive flight data are required to design space based cryogenic liquid storage and transfer systems with confidence. As NASA's mission concepts evolve, the demand for optimized in-space cryogenic systems is increasing. Cryogenic Orbital Nitrogen Experiment (CONE) is an attached shuttle payload experiment designed to address major technological issues associated with on-orbit storage and supply of cryogenic liquids. During its 7 day mission, CONE will conduct experiments and technology demonstrations in active and passive pressure control, stratification and mixing, liquid delivery and expulsion efficiency, and pressurant bottle recharge. These experiments, conducted with liquid nitrogen as the test fluid, will substantially extend the existing low gravity fluid data base and will provide future system designers with vital performance data from an orbital environment
'An Apotheosis of Well-Being': Durkheim on austerity and double-dip recessions
This article is an attempt to contribute a view on the economic crisis from classical sociology, a voice often missing from the sociological response to the crisis. The work of Ămile Durkheim provides a unique perspective here centred on morality and inequality produced in a historical context akin to our neoliberal times. It is argued there are four key points to take from Durkheimâs work. Firstly, that the initial credit crunch can be more fully understood with reference to the economic anomie which Durkheim sees as âchronicâ in a time of marketization. Secondly, that this creates an antagonistic relationship between a supposedly self-dependent rich and lazy poor. Thirdly, this conception of self-dependency and individual initiative makes any attempt to regulate the economy akin to sacrilege. Finally, the state is unwilling to intervene due to the emergence of âpseudo-democraciesâ. Therefore, Durkheimâs theory accounts for the initial crisis, austerity and double-dip recessions in a sociological framework. The article concludes by returning to the centrality of morality to the crisis for Durkheim and highlighting the omission of this in contemporary debates
Corrections to the universal behavior of the Coulomb-blockade peak splitting for quantum dots separated by a finite barrier
Building upon earlier work on the relation between the dimensionless interdot
channel conductance g and the fractional Coulomb-blockade peak splitting f for
two electrostatically equivalent dots, we calculate the leading correction that
results from an interdot tunneling barrier that is not a delta-function but,
rather, has a finite height V and a nonzero width xi and can be approximated as
parabolic near its peak. We develop a new treatment of the problem for g much
less than 1 that starts from the single-particle eigenstates for the full
coupled-dot system. The finiteness of the barrier leads to a small upward shift
of the f-versus-g curve at small values of g. The shift is a consequence of the
fact that the tunneling matrix elements vary exponentially with the energies of
the states connected. Therefore, when g is small, it can pay to tunnel to
intermediate states with single-particle energies above the barrier height V.
The correction to the zero-width behavior does not affect agreement with recent
experimental results but may be important in future experiments.Comment: Title changed from ``Non-universal...'' to ``Corrections to the
universal...'' No other changes. 10 pages, 1 RevTeX file with 2 postscript
figures included using eps
Detection of Coulomb Charging around an Antidot in the Quantum Hall Regime
We have detected oscillations of the charge around a potential hill (antidot)
in a two-dimensional electron gas as a function of a large magnetic field B.
The field confines electrons around the antidot in closed orbits, the areas of
which are quantised through the Aharonov-Bohm effect. Increasing B reduces each
state's area, pushing electrons closer to the centre, until enough charge
builds up for an electron to tunnel out. This is a new form of the Coulomb
blockade seen in electrostatically confined dots. Addition and excitation
spectra in DC bias confirm the Coulomb blockade of tunnelling.Comment: 4 pages, 4 Postscript figure
Existence of solutions for a higher order non-local equation appearing in crack dynamics
In this paper, we prove the existence of non-negative solutions for a
non-local higher order degenerate parabolic equation arising in the modeling of
hydraulic fractures. The equation is similar to the well-known thin film
equation, but the Laplace operator is replaced by a Dirichlet-to-Neumann
operator, corresponding to the square root of the Laplace operator on a bounded
domain with Neumann boundary conditions (which can also be defined using the
periodic Hilbert transform). In our study, we have to deal with the usual
difficulty associated to higher order equations (e.g. lack of maximum
principle). However, there are important differences with, for instance, the
thin film equation: First, our equation is nonlocal; Also the natural energy
estimate is not as good as in the case of the thin film equation, and does not
yields, for instance, boundedness and continuity of the solutions (our case is
critical in dimension in that respect)
A Novel Calculus? Institutional Change, Globalization and Industrial Conflict in Europe
Collective industrial conflict in Europe has declined dramatically since the 1970s. This decline is the result of significant changes in institutional factors, influencing the calculations of employees and their organizations when considering strike action. Declining union density and changes in market protection seem major influences, while institutional and legal changes are important explanations of persistent major inter-country variance. This indicates a novel industrial conflict calculus for employees, which entails a more restricted use, but not the withering away of the strike
Questioning policy, youth participation and lifestyle sports
Young people have been identified as a key target group for whom participation in sport and physical activity could have important benefits to health and wellbeing and consequently have been the focus of several government policies to increase participation in the UK. Lifestyle sports represent one such strategy for encouraging and sustaining new engagements in sport and physical activity in youth groups, however, there is at present a lack of understanding of the use of these activities within policy contexts. This paper presents findings from a government initiative which sought to increase participation in sport for young people through provision of facilities for mountain biking in a forest in south-east England. Findings from qualitative research with 40 young people who participated in mountain biking at the case study location highlight the importance of non-traditional sports as a means to experience the natural environments through forms of consumption which are healthy, active and appeal to their identities. In addition, however, the paper raises questions over the accessibility of schemes for some individuals and social groups, and the ability to incorporate sports which are inherently participant-led into state-managed schemes. Lifestyle sports such as mountain biking involve distinct forms of participation which present a challenge for policy-makers who seek to create and maintain sustainable communities of youth participants
Tunneling through a multigrain system: deducing the sample topology from the nonlinear conductance
We study a current transport through a system of a few grains connected with
tunneling links. The exact solution is given for an arbitrarily connected
double-grain system with a shared gate in the framework of the orthodox model.
The obtained result is generalized for multigrain systems with strongly
different tunneling resistances. We analyse the large-scale nonlinear
conductance and demonstrate how the sample topology can be unambiguously
deduced from the spectroscopy pattern (differential conductance versus
gate-bias plot). We present experimental data for a multigrain sample and
reconstruct the sample topology. A simple selection rule is formulated to
distinguish samples with spectral patterns free from spurious disturbance
caused by recharging of some grains nearby. As an example, we demonstrate
experimental data with additional peaks in the spectroscopy pattern, which can
not be attributed to coupling to additional grains. The described approach can
be used to judge the sample topology when it is not guaranteed by fabrication
and direct imaging is not possible.Comment: 13 pages (including 8 figures
Coherent Resonant Tunneling Through an Artificial Molecule
Coherent resonant tunneling through an artificial molecule of quantum dots in
an inhomogeneous magnetic field is investigated using an extended Hubbard
model. Both the multiterminal conductance of an array of quantum dots and the
persistent current of a quantum dot molecule embedded in an Aharanov-Bohm ring
are calculated. The conductance and persistent current are calculated
analytically for the case of a double quantum dot and numerically for larger
arrays using a multi-terminal Breit-Wigner type formula, which allows for the
explicit inclusion of inelastic processes. Cotunneling corrections to the
persistent current are also investigated, and it is shown that the sign of the
persistent current on resonance may be used to determine the spin quantum
numbers of the ground state and low-lying excited states of an artificial
molecule. An inhomogeneous magnetic field is found to strongly suppress
transport due to pinning of the spin-density-wave ground state of the system,
and giant magnetoresistance is predicted to result from the ferromagnetic
transition induced by a uniform external magnetic field.Comment: 23 pages, 12 figure
The Paradoxes of Democracy and the Rule of Law
The promise of modernization after the Second World War was that economic growth, equality, the rule of law and democracy would proceed together. In many ways, this has happened. Yet many of the promises of social progress developed after WWII have been undermined by internal tensions within the democratic project, as well as by social and economic trends. While stating the challenges that these trends have posed for democratic institutions and actors, we also look at the responses (both proposals and practices) that have emerged in order to address those challenges. In doing this, we note that the very conception of democracy as liberal democracy (based on delegation and majority voting) is under stress as neoliberalism has attacked those very intermediary institutions (parties, unions, voluntary associations) that had been at the basis of the development of the welfare state and democratic capitalism. We start by noting the growth in inequality, which means that formal democracy is shaped by uneven power resources as concentration of wealth provides advantages in the capacity to influence public decision making with mutual convertibility of economic and political resources. The spiral of inequality and corporate political power is reflected in a growing legitimacy crisis in old and new democracies. Liberalism, which promised the separation between the state and the market, has evolved into neoliberalism, , based on the domination of the corporation, exacerbated by privatization and de-regulation. This has raised private profit criteria about considerations of the broader public good and in many cases encouraged corruption. The ensuing inefficiency and lack of transparency foster institutional mistrust, with perverse effects. Challenges are also related to the fact that democracy has been mainly defined in a national mode, with the demos identified as the nation. Economic rescaling produced by global capitalism has however a produced both de-territorialization and re-territorialization, which requires a (yet unachieved) rethinking of the basis for democracy but also of welfare and its foundation in both identities and institutions. In the North and (with different characteristics) in the South of the globe, movement of capital and of people pose challenges of national pluralism and its constitutional recognition, questioning key concepts such as the definition of political community and popular sovereignty and the . relationship between human rights and citizenship. Citizenship is more appropriately considered as related not to fixed institutions but rather as âacts of citizenshipsâ requiring subjectivity and agency and more inclusive conceptions. The main actors in democratic development have been affected by these challenges. Political parties are an important element in democracy but they have become an interest in their own right. A crisis of representation has emerged from growing social detachment of political parties from social cleavages as well as of elected representatives from the citizens. This had most dramatic effects on the Left, when left-wing parties have supported neoliberal reforms. Relying on expertise for the development of progressive policies is not a solution given the non-accountable power of science as well as the increasing challenges of privatization of knowledge-making, opacity of knowledge production and persistence of fundamental class imbalances in access to knowledge. Participatory channels of access to institutions have been opened to âordinary citizensâ but, within neoliberalism, they are often based on individualist conceptions and do not address fundamental issues of inequalities. While citizens often call for direct participation, existing experiments rarely empower the citizens. While the judiciary has been seen as a surrogate for democratic participation for marginalized minority groups, its capacity for rights enforcement is limited by the expansion (in particular at international level) of a lex mercatoria as well as the use of courts in order to protect economic freedom from democratic dynamics. The rule of law has also been subverted by unequal access to the law and by the influence of money while the judiciary also has its own particular interests and corporate lawyers assume a brokerage function in globalized markets. On the other hand, in the control of political dissent, the state, rather than being weakened from globalization, increases its reach and power. The âwar on terrorâ has been used to challenge the rule of law by states of emergency as well as authoritarian drifts with attempts at imposing a permanent âstate of exceptionâ. On the other hand, progressive social movements have addressed growing inequalities and democratic crises by developing alternative visions of democracy, stressing participation over delegation and deliberation over majoritarian decision-making. Participatory and deliberative conceptions have been prefigured as well as elaborated in recent waves of protests. The consolidation of oppositional actors, however, faces challenges in the fragmentation of the potential social bases, the need to build a new collective identity as well as to establish channels of access to power. This has resulted from, but also triggered, the reduction in citizensâ entitlements and the weakening of the social contract upon which social progress depends
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