1,380 research outputs found

    The Specific Heat of a Ferromagnetic Film.

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    We analyze the specific heat for the O(N)O(N) vector model on a dd-dimensional film geometry of thickness LL using ``environmentally friendly'' renormalization. We consider periodic, Dirichlet and antiperiodic boundary conditions, deriving expressions for the specific heat and an effective specific heat exponent, \alpha\ef. In the case of d=3d=3, for N=1N=1, by matching to the exact exponent of the two dimensional Ising model we capture the crossover for \xi_L\ra\infty between power law behaviour in the limit {L\over\xi_L}\ra\infty and logarithmic behaviour in the limit {L\over\xi_L}\ra0 for fixed LL, where ξL\xi_L is the correlation length in the transverse dimensions.Comment: 21 pages of Plain TeX. Postscript figures available upon request from [email protected]

    Scaling of the specific heat in superfluid films

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    We study the specific heat of the xyx-y model on lattices L×L×HL \times L \times H with LHL \gg H (i.e. on lattices representing a film geometry) using the Cluster Monte--Carlo method. In the HH--direction we apply Dirichlet boundary conditions so that the order parameter in the top and bottom layers is zero. We find that our results for the specific heat of various thickness size HH collapse on the same universal scaling function. The extracted scaling function of the specific heat is in good agreement with the experimentally determined universal scaling function using no free parameters.Comment: 4 pages, uuencoded compressed PostScrip

    Understanding the nature of psychiatric comorbidity in migraine: A systematic review focused on interactions and treatment implications

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    Background: Migraine is a highly prevalent and disabling neurological disorder which is commonly linked with a broad range of psychiatric comorbidities, especially among subjects with migraine with aura or chronic migraine. Defining the exact nature of the association between migraine and psychiatric disorders and bringing out the pathophysiological mechanisms underlying the comorbidity with psychiatric conditions are relevant issues in the clinical practice. Methods: A systematic review of the most relevant studies about migraine and psychiatric comorbidity was performed using "PubMed", "Scopus", and "ScienceDirect" electronic databases from 1 January 1998 to 15 July 2018. Overall, 178 studies met our inclusion criteria and were included in the current review. Results: According to the most relevant findings of our overview, the associations with psychiatric comorbidities are complex, with a bidirectional association of major depression and panic disorder with migraine. Importantly, optimizing the pharmacological and non-pharmacological treatment of either migraine or its psychiatric comorbidities might help clinicians to attenuate the burden of both these conditions. Conclusions: The available data highlight the need for a comprehensive evaluation of psychiatric disorders in migraine in order to promote an integrated model of care and carefully address the burden and psychosocial impairment related to psychiatric comorbidities in migraine

    InterMiG: international differences in the therapeutic approach to migraine patients in specialized headache centers

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    Antidepressiu; Migranya; Tractament preventiuAntidepresivo; Migraña; Tratamiento preventivoAntidepressant; Migraine; Preventive treatmentBackground There is currently a wide therapeutic arsenal for migraine patients, without a single first-line preventive drug and we choose the different available alternatives taking into account comorbidities, national guidelines, previous treatments and personal experiences. Our objective was to evaluate the differences in the use of migraine treatments between neurologists from different countries. Methods This is a multi-centre observational study carried out by neurologists from specialized headache units in seven countries, retrospective with consecutive inclusion of all patients presenting with a migraine diagnosis, over a period of three months. Results A total of 734 patients were recruited but only 600 were considered in the analysis in order to homogenize the patient cohorts from countries: 200 Spain (ES), 100 Italy (IT), 85 Russia (RUS), 80 Germany (DE), 60 Portugal (PT), 45 Poland (PL) and 30 Australia (AU). 85.4 % of patients were women with a mean age of 42.6 ± 11.8 years. Considering previous and current preventive treatment, the order of use was: antidepressants (69.3 %), antiepileptic drugs (54.7 %), beta-blockers and antihypertensive drugs (49.7 %), OnabotulinumtoxinA (44.0 %) and others (36.2 %). Statistically significant differences were found between all pharmacological classes: antidepressants were commonly used in all countries, with the exception of Poland (AU: 76.7 %, IT: 71.0 %, DE: 60.0 %, PL: 31.1 %, PT: 71.7 %, RUS: 70.6 %, ES: 78.5 %; p < 0.0001); antiepileptic drugs were more frequently prescribed in Portugal, Australia and Spain (AU: 73.3 %, IT: 40.0 %, DE: 37.5 %, PL: 48.9 %, PT: 85.0 %, RUS: 29.4 % and ES: 69.0 %; p < 0.0001); beta-blockers and antihypertensive drugs were frequently used in all countries except Italy (AU: 60.0 %, IT: 14.0 %, DE: 53.8 %, PL: 48.9 %, PT: 68.3 %, RUS: 49.4 % and ES: 59.0 %; p < 0.0001); BTX-A were predominately used in Spain, Italy and Australia (AU:56.7 %, IT:58.0 %, DE:20.0 %, PL: 42.2 %, PT: 26.7 %, RUS: 24.7 % and ES: 58.5 %; p < 0.0001) and others were most frequently used in Poland (AU: 0.0 %, IT: 19.0 %, DE: 42.5 %, PL: 95.6 %, PT: 31.7 %, RUS: 3.5 % and ES: 49.5 %; p < 0.0001). If only patients without comorbidities are considered (200/600), statistically differences between countries persist in all preventive treatments. Conclusions There is heterogeneity in the choice of preventive treatment between different countries. Prospective comparative studies of the different oral and subcutaneous alternatives would help to create a global therapeutic algorithm that would guarantee the best option for our patients.This work did not receive any funds

    The three-nucleon bound state using realistic potential models

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    The bound states of 3^3H and 3^3He have been calculated using the Argonne v18v_{18} plus the Urbana three-nucleon potential. The isospin T=3/2T=3/2 state have been included in the calculations as well as the nn-pp mass difference. The 3^3H-3^3He mass difference has been evaluated through the charge dependent terms explicitly included in the two-body potential. The calculations have been performed using two different methods: the solution of the Faddeev equations in momentum space and the expansion on the correlated hyperspherical harmonic basis. The results are in agreement within 0.1% and can be used as benchmark tests. Results for the CD-Bonn interaction are also presented. It is shown that the 3^3H and 3^3He binding energy difference can be predicted model independently.Comment: 5 pages REVTeX 4, 1 figures, 6 table

    Changes in western Mediterranean thermohaline circulation in association with a deglacial Organic Rich Layer formation in the Alboran Sea

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    We thank the constructive comments of three anonymous reviewers that substantially improved this manuscript. JNPA has been funded by a Postdoctoral fellowship Beatriu de Pinós funded by the AGAUR from the Generalitat de Catalunya and the European Union through the Marie Curie-COFUND actions. LDP acknowledges support from the Ramón y Cajal program (MINECO, Spain), JF from the Serra Húnter Programme (Generalitat de Catalunya) and IC from the ICREA-Academia program from the Generalitat de Catalunya. We are indebted to Albert Català and Montse Guart (University of Barcelona), and Joaquim Perona and Regina Roca (CCiT-UB) for their support with the laboratory work.Supplementary data to this article can be found online at https://doi.org/10.1016/j.quascirev.2019.106075.The accumulation of an Organic Rich Layer (ORL) during the last deglaciation in the Alboran Sea (western Mediterranean Sea) and its link to changes in deep and intermediate water circulation are here investigated. Benthic foraminiferal assemblages and the shallow infaunal foraminifer Uvigerina peregrina δ13C record support the establishment of sustained high organic matter fluxes, and thus eutrophic conditions at the sea floor, during the late phase of the ORL (Younger Dryas to early Holocene periods). Since organic matter fluxes were lower (mesotrophic conditions) during the Bølling-Allerød period, they cannot be solely responsible for the ORL initiation. Geochemical, sedimentological and micropalaeontological proxies support a major weakening of the deep-water convection in the Gulf of Lion as the main driver for the development of poorly-ventilated conditions from intermediate depths (946 m) to the deep western Mediterranean basin that promoted the beginning of the ORL deposition. Nevertheless, a better ventilation at intermediate depths was established during the late ORL, while the deep basin remained poorly ventilated. We propose that our data reflect the arrival of a new better-ventilated intermediate water mass analogue to the current Levantine Intermediate Water (LIW) and/or a new intermediate water mass from the Gulf of Lion. The ultimate source of this water mass needs to be further explored but chronologies of the changes recorded here indicate that intermediate and deep ventilation phases were decoupled between the western and eastern Mediterranean basins during the deglaciation and early-middle Holocene.This work was funded by the projects TIMED (Call ref: ERC-CoG-2015; proposal number 683237) of the European Research Council (Consolidator Grants), CHIMERA (CTM2016-75411-R), CGL2015-66835-P and RTI2018-099489-B-I00 of the Ministerio de Economía y Competitividad of Spain. The Research Group GRC Geociències Marines (2017 SGR 315) of the Generalitat de Catalunya is also acknowledged, as well as the Research Groups RNM-178 and RNM-190 (Junta de Andalucía)

    The detection of neutron clusters

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    A new approach to the production and detection of bound neutron clusters is presented. The technique is based on the breakup of beams of very neutron-rich nuclei and the subsequent detection of the recoiling proton in a liquid scintillator. The method has been tested in the breakup of 11Li, 14Be and 15B beams by a C target. Some 6 events were observed that exhibit the characteristics of a multineutron cluster liberated in the breakup of 14Be, most probably in the channel 10Be+4n. The various backgrounds that may mimic such a signal are discussed in detail.Comment: 11 pages, 12 figures, LPCC 01-1

    Perturbative calculation of the scaled factorial moments in second-order quark-hadron phase transition within the Ginzburg-Landau description

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    The scaled factorial moments FqF_q are studied for a second-order quark-hadron phase transition within the Ginzburg-Landau description. The role played by the ground state of the system under low temperature is emphasized. After a local shift of the order parameter the fluctuations are around the ground state, and a perturbative calculation for FqF_q can be carried out. Power scaling between FqF_q's is shown, and a universal scaling exponent ν1.75\nu\simeq 1.75 is given for the case with weak correlations and weak self-interactions.Comment: 12 pages in RevTeX, 12 eps figure

    The nucleon-nucleon interaction

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    We review the major progress of the past decade concerning our understanding of the nucleon-nucleon interaction. The focus is on the low-energy region (below pion production threshold), but a brief outlook towards higher energies is also given. The items discussed include charge-dependence, the precise value of the πNN\pi NN coupling constant, phase shift analysis and high-precision NN data and potentials. We also address the issue of a proper theory of nuclear forces. Finally, we summarize the essential open questions that future research should be devoted to.Comment: 42 pages, 12 figures, iopart.cls style; Topical Review prepared for J. Phys. G: Nucl. Part. Phy

    The effect of a high-polyphenol Mediterranean diet (Green-MED) combined with physical activity on age-related brain atrophy: The Dietary Intervention Randomized Controlled Trial Polyphenols Unprocessed Study (DIRECT PLUS)

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    Background: The effect of diet on age-related brain atrophy is largely unproven. Objectives: We aimed to explore the effect of a Mediterranean diet (MED) higher in polyphenols and lower in red/processed meat (Green-MED diet) on age-related brain atrophy. Methods: This 18-mo clinical trial longitudinally measured brain structure volumes by MRI using hippocampal occupancy score (HOC) and lateral ventricle volume (LVV) expansion score as neurodegeneration markers. Abdominally obese/dyslipidemic participants were randomly assigned to follow 1) healthy dietary guidelines (HDG), 2) MED, or 3) Green-MED diet. All subjects received free gym memberships and physical activity guidance. Both MED groups consumed 28 g walnuts/d (+440 mg/d polyphenols). The Green-MED group consumed green tea (3-4 cups/d) and Mankai (Wolffia-globosa strain, 100 g frozen cubes/d) green shake (+800 mg/d polyphenols). Results: Among 284 participants (88% men; mean age: 51 y; BMI: 31.2 kg/m2; APOE-ε4 genotype = 15.7%), 224 (79%) completed the trial with eligible whole-brain MRIs. The pallidum (-4.2%), third ventricle (+3.9%), and LVV (+2.2%) disclosed the largest volume changes. Compared with younger participants, atrophy was accelerated among those ≥50 y old (HOC change: -1.0% ± 1.4% compared with -0.06% ± 1.1%; 95% CI: 0.6%, 1.3%; P Conclusions: A Green-MED (high-polyphenol) diet, rich in Mankai, green tea, and walnuts and low in red/processed meat, is potentially neuroprotective for age-related brain atrophy.This trial was registered at clinicaltrials.gov as NCT03020186
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