64 research outputs found
Attractive Solution of Binary Bose Mixtures: Liquid-Vapor Coexistence and Critical Point
We study the thermodynamic behavior of attractive binary Bose mixtures using
exact path-integral Monte-Carlo methods. Our focus is on the regime of
interspecies interactions where the ground state is in a self-bound liquid
phase, stabilized by beyond mean-field effects. We calculate the isothermal
curves in the pressure vs density plane for different values of the attraction
strength and establish the extent of the coexistence region between liquid and
vapor using the Maxwell construction. Notably, within the coexistence region,
Bose-Einstein condensation occurs in a discontinuous way as the density jumps
from the normal gas to the superfluid liquid phase. Furthermore, we determine
the critical point where the line of first-order transition ends and
investigate the behavior of the density discontinuity in its vicinity. We also
point out that the density discontinuity at the transition could be observed in
experiments of mixtures in traps.Comment: v1: 6 pages, 5 figures. Supplemental material: 4 pages, 2 figures.
Data available on zenodo.org; v2: minor improvements, matches PRL published
versio
Thermal-induced Local Imbalance in Repulsive Binary Bose Mixtures
We study repulsive two-component Bose mixtures with equal populations and
confined in a finite-size box through path-integral Monte Carlo simulations.
For different values of the -wave scattering length of the interspecies
potential, we calculate the local population imbalance in a region of fixed
volume inside the box at different temperatures. We find two different
behaviors: for phase-separated states at , thermal effects induce a
diffusion process which reduces the local imbalance whereas, for miscible
states at , a maximum in the local population imbalance appears at a
certain temperature, below the critical one. We show that this intriguing
behavior is strongly related to the bunching effect associated with the
Bose-Einstein statistics of the particles in the mixture and to an unexpected
behavior of the cross pair distribution function not reported before.Comment: 7 pages, 7 figure
Fermi-Liquid Behavior of the Normal Phase of a Strongly Interacting Gas of Cold Atoms
International audienceWe measure the magnetic susceptibility of a Fermi gas with tunable interactions in the low-temperature limit and compare it to quantum Monte Carlo calculations. Experiment and theory are in excellent agreement and fully compatible with the Landau theory of Fermi liquids. We show that these measure- ments shed new light on the nature of the excitations of the normal phase of a strongly interacting Fermi gas
Organizzazione e valutazione della didattica nella Facoltà di Economia di Modena
Il lavoro esamina gli aspetti essenziali dell'organizzazione dei corsi, del carico didattico, del calendario delle lezioni, della prestazione degli studenti, del processo di apprendimento, del sistema europeo di trasferimento dei crediti, del monitoraggio e della valutazione della didattica a livello di tutta la Facoltà di Economia.NOTA: il testo è curato da G. Ricci e M. Lalla; gli altri autori indicati hanno contribuito a scrivere uno o piú paragrafi
Insomnia and Migraine: A Missed Call?
: Migraine is one of the most prevalent and disabling neurological conditions, presenting episodes of throbbing headache that limit activities of daily living. Several factors may influence migraine frequency, such as lifestyle or alcohol consumption. Among the most recognised ones, sleep plays a biunivocal role, since poor sleep quality may worsen migraine frequency, and a high migraine frequency may affect sleep quality. In this paper, the authors evaluate the relationship between migraine and insomnia by exploring a cohort of patients affected by episodic or chronic migraine. To do so, a phone interview was performed, asking patients about their migraine frequency and mean pain intensity, in addition to the questions of the Insomnia Severity Index. The last one explores several symptoms impairing sleep that focus on insomnia. Patients complaining of insomnia showed an increased migraine frequency, and a weak but significant correlation was found between headache days per month and insomnia scores. Such results were particularly evident in patients affected by chronic migraine. Such results suggest how insomnia, in the presented data, seems to be associated with migraine frequency but not with pain intensity
The Clinical Relevance of Artificial Intelligence in Migraine
: Migraine is a burdensome neurological disorder that still lacks clear and easily accessible diagnostic biomarkers. Furthermore, a straightforward pathway is hard to find for migraineurs' management, so the search for response predictors has become urgent. Nowadays, artificial intelligence (AI) has pervaded almost every aspect of our lives, and medicine has not been missed. Its applications are nearly limitless, and the ability to use machine learning approaches has given researchers a chance to give huge amounts of data new insights. When it comes to migraine, AI may play a fundamental role, helping clinicians and patients in many ways. For example, AI-based models can increase diagnostic accuracy, especially for non-headache specialists, and may help in correctly classifying the different groups of patients. Moreover, AI models analysing brain imaging studies reveal promising results in identifying disease biomarkers. Regarding migraine management, AI applications showed value in identifying outcome measures, the best treatment choices, and therapy response prediction. In the present review, the authors introduce the various and most recent clinical applications of AI regarding migraine
Sleep and Chronobiology as a Key to Understand Cluster Headache
: The cluster headache is a primary headache characterized by attacks of unilateral pain associated with ipsilateral cranial autonomic features. These attacks recur in clusters during the years alternating with periods of complete remission, and their onset is often during the night. This annual and nocturnal periodicity hides a strong and mysterious link among CH, sleep, chronobiology and circadian rhythm. Behind this relationship, there may be the influence of genetic components or of anatomical structures such as the hypothalamus, which are both involved in regulating the biological clock and contributing even to the periodicity of cluster headaches. The bidirectional relationship manifests itself also with the presence of sleep disturbances in patients affected by cluster headaches. What if the key to studying the physiopathology of such disease could rely on the mechanisms of chronobiology? The purpose of this review is to analyze this link in order to interpret the pathophysiology of cluster headaches and the possible therapeutic implications
The Singularity Problem for Space-Times with Torsion
The problem of a rigorous theory of singularities in space-times with torsion
is addressed. We define geodesics as curves whose tangent vector moves by
parallel transport. This is different from what other authors have done,
because their definition of geodesics only involves the Christoffel connection,
though studying theories with torsion. We propose a preliminary definition of
singularities which is based on timelike or null geodesic incompleteness, even
though for theories with torsion the paths of particles are not geodesics. The
study of the geodesic equation for cosmological models with torsion shows that
the definition has a physical relevance. It can also be motivated, as done in
the literature, remarking that the causal structure of a space-time with
torsion does not get changed with respect to general relativity. We then prove
how to extend Hawking's singularity theorem without causality assumptions to
the space-time of the ECSK theory. This is achieved studying the generalized
Raychaudhuri equation in the ECSK theory, the conditions for the existence of
conjugate points and properties of maximal timelike geodesics. Hawking's
theorem can be generalized, provided the torsion tensor obeys some conditions.
Thus our result can also be interpreted as a no-singularity theorem if these
additional conditions are not satisfied. In other words, it turns out that the
occurrence of singularities in closed cosmological models based on the ECSK
theory is less generic than in general relativity. Our work is to be compared
with previous papers in the literature. There are some relevant differences,
because we rely on a different definition of geodesics, we keep the field
equations of the ECSK theory in their original form rather than casting them in
a form similar to general relativity with a modified energy momentum tensor,Comment: 17 pages, plain-tex, published in Nuovo Cimento B, volume 105, pages
75-90, year 199
Molecular analysis of post-harvest withering in grape by AFLP transcriptional profiling
Post-harvest withering of grape berries is used in the production of dessert and fortified wines to alter must quality characteristics and increase the concentration of simple sugars. The molecular processes that occur during withering are poorly understood, so a detailed transcriptomic analysis of post-harvest grape berries was carried out by AFLP-transcriptional profiling analysis. This will help to elucidate the molecular mechanisms of berry withering and will provide an opportunity to select markers that can be used to follow the drying process and evaluate different drying techniques. AFLP-TP identified 699 withering-specific genes, 167 and 86 of which were unique to off-plant and on-plant withering, respectively. Although similar molecular events were revealed in both withering processes, it was apparent that off-plant withering induced a stronger dehydration stress response resulting in the high level expression of genes involved in stress protection mechanisms, such as dehydrin and osmolite accumulation. Genes involved in hexose metabolism and transport, cell wall composition, and secondary metabolism (particularly the phenolic and terpene compound pathways) were similarly regulated in both processes. This work provides the first comprehensive analysis of the molecular events underpinning post-harvest withering and could help to define markers for different withering processes
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