Ultracold polarized Fermi gas at intermediate temperatures

We consider non-zero temperature properties of the polarized two-component Fermi gas. We point out that stable polarized paired states which are more stable than their phase separated counterparts with unpolarized superfluid region can exist below the critical temperature. We also solve the system behavior in a trap using the local density approximation and find gradually increasing polarization in the center of the system as the temperature is increased. However, in the strongly interacting region the central polarization increases most rapidly close to the mean-field critical temperature, which is known to be substantially higher than the critical temperature for superfluidity. This indicates that most of the phase separation occurs in the fluctuation region prior to superfluidity and that the polarization in the actual superfluid is modest.Comment: Final published versio

Interaction-induced current-reversals in driven lattices

We demonstrate that long-range interactions can cause, as time evolves, consecutive reversals of directed currents for dilute ensembles of particles in driven lattices. These current-reversals are based on a general mechanism which leads to an interaction-induced accumulation of particles in the regular regions of the underlying single-particle phase space and to a synchronized single-particle motion as well as an enhanced efficiency of Hamiltonian ratchets.Comment: 5 pages, 5 figure

Graphs of large girth and surfaces of large systole

The systole of a hyperbolic surface is bounded by a logarithmic function of its genus. This bound is sharp, in that there exist sequences of surfaces with genera tending to infinity that attain logarithmically large systoles. These are constructed by taking congruence covers of arithmetic surfaces. In this article we provide a new construction for a sequence of surfaces with systoles that grow logarithmically in their genera. We do this by combining a construction for graphs of large girth and a count of the number of $\mathrm{SL}_2(\mathbb{Z})$ matrices with positive entries and bounded trace

Pheochromocytomas and paragangliomas: from DNA to the daily clinical practice

The neuroendocrine system is a diffuse system in which the nervous system and the hormones of the endocrine glands interact. The neuroendocrine organs of the sympathetic and parasympathetic autonomic nervous system are called paraganglia. These organs usually manifest as anatomically discrete bodies, which derive from the neural crest and produce catecholamines and various peptides. Various localizations of paraganglia in the human body are known, including the adrenal gland, organs of Zuckerkandl, and carotid and aortic bodies. Paraganglia are divided into two functional groups, i.e. the sympathoadrenal and the parasympathetic autonomic nervous system. Sympathetic paraganglia are predominantly located in the prevertebral and paravertebral sympathetic trunks, and along the fibers of the hypogastric plexus, innervating pelvic and retroperitoneal organs. Parasympathetic paraganglia are almost exclusively located in the region of cranial as well as thoracic branches of the of the glossopharyngeal nerves and vagal nerves. The principal glossopharyngeal paraganglia are the tympanic (located in the wall of the middle ear), and the carotid bodies (Figure 1). Neoplasms of the paraganglia are called pheochromocytomas (PCC), sympathetic and parasympathetic paragangliomas. The name PCC is derived from the Greek synonym “dark colored tumor”, because it was first described by Pick as a chromium salt-reactive tumor which lead to dark coloration. PCC are tumors which originate in the adrenal medulla. Sympathetic paragangliomas (sPGL), in the literature often described as extra-adrenal PCC, usually produce catecholamines and occur in the abdominal cavity and the aorticopulmonary bodies, but not in the adrenal medulla. Parasympathetic paragangliomas, also called head and neck paraganglioma, usually do not produce catecholamines and are situated in the wall of the middle ear, along the vagal nerve, and the carotid and jugular bodies. In the literature they are still often referred to as chemodectomas, glomus tumors, or carotid body tumors

A thermodynamical fiber bundle model for the fracture of disordered materials

We investigate a disordered version of a thermodynamic fiber bundle model proposed by Selinger, Wang, Gelbart, and Ben-Shaul a few years ago. For simple forms of disorder, the model is analytically tractable and displays some new features. At either constant stress or constant strain, there is a non monotonic increase of the fraction of broken fibers as a function of temperature. Moreover, the same values of some macroscopic quantities as stress and strain may correspond to different microscopic cofigurations, which can be essential for determining the thermal activation time of the fracture. We argue that different microscopic states may be characterized by an experimentally accessible analog of the Edwards-Anderson parameter. At zero temperature, we recover the behavior of the irreversible fiber bundle model.Comment: 18 pages, 10 figure

Circadian Organization in Hemimetabolous Insects

The circadian system of hemimetabolous insects is reviewed in respect to the locus of the circadian clock and multioscillatory organization. Because of relatively easy access to the nervous system, the neuronal organization of the clock system in hemimetabolous insects has been studied, yielding identification of the compound eye as the major photoreceptor for entrainment and the optic lobe for the circadian clock locus. The clock site within the optic lobe is inconsistent among reported species; in cockroaches the lobula was previously thought to be a most likely clock locus but accessory medulla is recently stressed to be a clock center, while more distal part of the optic lobe including the lamina and the outer medulla area for the cricket. Identification of the clock cells needs further critical studies. Although each optic lobe clock seems functionally identical, in respect to photic entrainment and generation of the rhythm, the bilaterally paired clocks form a functional unit. They interact to produce a stable time structure within individual insects by exchanging photic and temporal information through neural pathways, in which serotonin and pigment-dispersing factor (PDF) are involved as chemical messengers. The mutual interaction also plays an important role in seasonal adaptation of the rhythm

Exponential torsion growth for random 3-manifolds

We show that a random 3-manifold with positive first Betti number admits a tower of cyclic covers with exponential torsion growth

Directed transport and localization in phase-modulated driven lattices

We explore the dynamics of non-interacting particles loaded into a phase-modulated one-dimensional lattice formed by laterally oscillating square barriers. Tuning the parameters of the driven unit cell of the lattice selected parts of the classical phase space can be manipulated in a controllable manner. We find superdiffusion in position space for all parameters regimes. A directed current of an ensemble of particles can be created through locally breaking the spatiotemporal symmetries of the time-driven potential. Magnitude and direction of the current are tunable. Several mechanisms for transient localization and trapping of particles in different wells of the driven unit cell are presented and analyzed