6,720 research outputs found

    ESR theory for interacting 1D quantum wires

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    We compute the electron spin resonance (ESR) intensity for one-dimensional quantum wires in semiconductor heterostructures, taking into account electron-electron interactions and spin-orbit coupling. The ESR spectrum is shown to be very sensitive to interactions. While in the absence of interactions, the spectrum is a flat band, characteristic threshold singularities appear in the interacting limit. This suggests the practical use of ESR to reveal spin dynamics in a Luttinger liquid.Comment: 7 pages, 2 figures. To be published in Europhys. Let

    Thermodynamics of rotating self-gravitating systems

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    We investigate the statistical equilibrium properties of a system of classical particles interacting via Newtonian gravity, enclosed in a three-dimensional spherical volume. Within a mean-field approximation, we derive an equation for the density profiles maximizing the microcanonical entropy and solve it numerically. At low angular momenta, i.e. for a slowly rotating system, the well-known gravitational collapse ``transition'' is recovered. At higher angular momenta, instead, rotational symmetry can spontaneously break down giving rise to more complex equilibrium configurations, such as double-clusters (``double stars''). We analyze the thermodynamics of the system and the stability of the different equilibrium configurations against rotational symmetry breaking, and provide the global phase diagram.Comment: 12 pages, 9 figure

    Disentanglement among vitamins D

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    Vitamin D is essential for intestinal calcium absorption andtherefore crucial for skeletal health. In addition, its beneficialeffects extend outside bone tissue. The list of putative non-skeletal effects for which vitamin D adequacy is needed rangesfrom diseases at birth to those causing death. Associationsbetween a poor vitamin D status and endometriosis, uterinemyoma, dysmenorrhea, abnormal PAP smear results, and high-risk HPV infection of the cervix have also been described. Just tostay in our days, a possible favorable role of“vitamin D”in mod-ulating SARS-COV-2 infection has been demonstrated by some[1] but not all researchers. However, hypovitaminosis D (a termwe would prefer to indicate both deficiency and insufficiency, inanalogy with other clinical conditions, i.e. hypomagnesemia, hypo-calcemia, hyposideremia) is highly prevalent in the world

    Upper Triassic basinal carbonates between the Molise and Sannio Nappes near Frosolone (Duronia, Molise): geological implications.

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    E’ stata riconosciuta nell’area di Duronia (Molise) l’esistenza di dolomie e calcari dolomitici con selce del Trias superiore riferibili alla Formazione dei “Calcari con Selce” delle Unità Lagonegresi. Questi carbonati bacinali, presenti nella parte basale della Falda Sannitica in prossimità del contatto con le Falde Molisane (Unità di Frosolone), sono stati interpretati in passato come olistoliti all’interno delle Argille Varicolori, come depositi della successione sannitica o come depositi della successione sicilide e ad essi sono state attribuite età che vanno dal Cretaceo superiore al Miocene medio. L’esistenza di depositi bacinali triassici nella regione molisano-sannitica ha come implicazione paleogeografica la continuazione verso nord di un ramo del Bacino Lagonegrese e come implicazione tettonica un forte raccorciamento tra i massicci carbonatici riferibili alla Piattaforma Appenninica e quelli riferibili alla Piattaforma Simbruini-Matese

    Detecting the traders' strategies in Minority-Majority games and real stock-prices

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    Price dynamics is analyzed in terms of a model which includes the possibility of effective forces due to trend followers or trend adverse strategies. The method is tested on the data of a minority-majority model and indeed it is capable of reconstructing the prevailing traders' strategies in a given time interval. Then we also analyze real (NYSE) stock-prices dynamics and it is possible to derive an indication for the the ``sentiment'' of the market for time intervals of at least one day.Comment: 13 pages, 10 figure

    The X-ray properties of the magnetic cataclysmic variable UUColumbae

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    Aims. XMM-Newton observations to determine for the first time the broad-band X-ray properties of the faint, high galactic latitude intermediate polar UUCol are presented. Methods. We performed X-ray timing analysis in different energy ranges of the EPIC cameras, which reveals the dominance of the 863 s white dwarf rotational period. The spin pulse is strongly energy dependent. Weak variabilities at the beat 935 s and at the 3.5 h orbital periods are also observed, but the orbital modulation is detected only below 0.5 keV. Simultaneous UV and optical photometry shows that the spin pulse is anti-phased with respect to the hard X-rays. Analysis of the EPIC and RGS spectra reveals the complexity of the X-ray emission, which is composed of a soft 50 eV black–body component and two optically thin emission components at 0.2 keV and 11 keV strongly absorbed by dense material with an equivalent hydrogen column density of 1023 cm−2 that partially (50%) covers the X-ray source. Results. The complex X-ray and UV/optical temporal behaviour indicates that accretion occurs predominantly (∼80%) via a disc with a partial contribution (∼20%) directly from the stream. The main accreting pole dominates at high energies whilst the secondary pole mainly contributes in the soft X-rays and at lower energies. The bolometric flux ratio of the soft-to-hard X-ray emissions is found to be consistent with the prediction of the standard accretion shock model. We find the white dwarf in UUCol accretes at a low rate and possesses a low magnetic moment. It is therefore unlikely that UUCol will evolve into a moderate field strength polar, so that the soft X-ray intermediate polars still remain an enigmatic small group of magnetic cataclysmic variables

    Histamine plasma levels and elimination diet in chronic idiopathic urticaria

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    Abstract: Objective: The aim of this study was to evaluate the effects of an oligoantigenic and histamine-free diet on patients affected with chronic idiopathic urticaria (CIU). Design: Ten patients with chronic idiopathic urticaria were prescribed an oligoantigenic and histamine-free diet for 21 days, followed by serial and controlled reintroduction of foods during a further 70 days. Modification in clinical illness as well as histamine plasma levels, post-heparin plasma diamine oxidase (DAO) and intestinal permeability were evaluated. Results: The oligoantigenic and histamine-free diet induced a significant improvement of symptoms (P < 0.05). Moreover, CIU patients on free diet showed higher histamine plasma levels (P < 0.05 vs post-diet and vs controls) that fell to control levels during the oligoantigenic and histamine-free diet. Post-heparin plasma diamine oxidase values were slightly reduced and were unchanged during the diet as well as intestinal permeability, which was always normal in all patients. Conclusions: These data suggest that histamine plays a major role in chronic idiopathic urticaria. The finding of normal intestinal permeability suggests that a morphological damage of intestinal mucosa should be excluded in these patients. However, the presence of low levels of post-heparin plasma diamine oxidase may indicate a subclinical impairment of small bowel enterocyte function that could induce a higher sensitivity to histamine-rich or histamine-producing food
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