522 research outputs found
Experimental Signals of Phase Transition
The connection between the thermodynamics of charged finite nuclear systems
and the asymptotically measured partitions is presented. Some open questions,
concerning in particular equilibrium partitions are discussed. We show a
detailed comparison of the decay patterns in Au+ C,Cu,Au central collisions and
in Au quasi-projectile events. Observation of abnormally large fluctuations in
carefully selected samples of data is reported as an indication of a first
order phase transition (negative heat capacity) in the nuclear equation of
state.Comment: 8 pages, 8th International Conference on Nucleus-Nucleus Collisions,
Moscow 200
Looking for bimodal distributions in multi-fragmentation reactions
The presence of a phase transition in a finite system can be deduced,
together with its order, from the shape of the distribution of the order
parameter. This issue has been extensively studied in multifragmentation
experiments, with results that do not appear fully consistent. In this paper we
discuss the effect of the statistical ensemble or sorting conditions on the
shape of fragment distributions, and propose a new method, which can be easily
implemented experimentally, to discriminate between different fragmentation
scenarii. This method, based on a reweighting of the measured distribution to
account for the experimental constraints linked to the energy deposit, is
tested on different simple models, and appears to provide a powerful
discrimination.Comment: 11 pages, 7 figure
Interregional migration of human creative capital:The case of "Bohemian graduates"
The human capital endowment has long been perceived to be of paramount importance to regional growth and development. In recent years, there also has been a widely held belief that creativity, going hand in hand with innovation and knowledge creation, readily translates into regional competitiveness. Attracting quality human capital and cultivating creative industry/class have been given an unprecedented level of significance in regional policies. As a result of this, understanding the factors determining the migration behaviour of graduates – and especially graduates in creative disciplines – has clear implications for policy makers. In addressing these issues and advancing our understanding of the relationship between creativity and mobility in human capital, this study provides the first empirical analysis of the role played by graduates' subject background (i.e. creative vs. non-creative subjects) in influencing their migration choice in the UK. Our data employed in this paper primarily draw on the Destinations of Lea-vers from Higher Education Survey (DLHE) 2006/2007, collected by the UK's Higher Education Statistic Agency. Graduates are classified into five migration categories based on their migration choices from domicile to university and then onto workplace. Our results show that graduates from disciplines such as business/management and more importantly engineering/technology are more migratory and more likely to be repeat migrants and land higher paid jobs, while graduates from creative arts, education or law are less mobile and, on average, earn less
A Procedure to Calibrate a Multi-Modular Telescope
A procedure has been developed for the charge, mass and energy calibration of
ions produced in nuclear heavy ion reactions. The charge and mass
identification are based on a E-E technique. A computer code determines
the conversion from ADC channels into energy values, atomic number and mass of
the detected fragments by comparing with energy loss calculations through a
minimization routine. The procedure does not need prior measurements with beams
of known energy and charge. An application of this technique to the calibration
of the MULTICS apparatus is described.Comment: 9 pages, Tex file, 3 postscript figures available upon request from
[email protected]; to appear in Nucl. Inst. Met
Negative heat capacity in the critical region of nuclear fragmentation: an experimental evidence of the liquid-gas phase transition
An experimental indication of negative heat capacity in excited nuclear
systems is inferred from the event by event study of energy fluctuations in
quasi-projectile sources formed in collisions at 35 A.MeV. The
excited source configuration is reconstructed through a calorimetric analysis
of its de-excitation products. Fragment partitions show signs of a critical
behavior at about 5 A.MeV excitation energy. In the same energy range the heat
capacity shows a negative branch providing a direct evidence of a first order
liquid gas phase transition.Comment: 4 Postscript figures, submitted to Phys. Rev. Lett. on 14-apr-199
Signals of bimodality in the fragmentation of Au quasi-projectiles
Signals of bimodality have been investigated in experimental data of
quasi-projectile decay produced in Au+Au collisions at 35 AMeV. This same data
set was already shown to provide several signals characteristic of a first
order, liquid-gas-like phase transition. Different event sortings proposed in
the recent literature are analyzed. A sudden change in the fragmentation
pattern is revealed by the distribution of the charge of the largest fragment,
compatible with a bimodal behavior.Comment: 17 pages, 8 figures, submitted to Nuclear Physics
Neuroendocrine tumor presenting like lymphoma: a case report
INTRODUCTION: Neuroendocrine tumors are a rare but diverse group of malignancies that arise in a wide range of organ systems, including the mediastinum. Differential diagnosis includes other masses arising in the middle mediastinum such as lymphoma, pericardial, bronchogenic and enteric cysts, metastatic tumors, xanthogranuloma, systemic granuloma, diaphragmatic hernia, meningocele and paravertebral abscess. CASE PRESENTATION: We present a case of 42-year-old Caucasian man with a neuroendocrine tumor of the middle-posterior mediastinum and liver metastases, which resembled a lymphoma on magnetic resonance imaging. CONCLUSION: The differential diagnosis in patients with mediastinal masses and liver lesions should include neuroendocrine tumor
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