Lower and upper bounds on the fidelity susceptibility

We derive upper and lower bounds on the fidelity susceptibility in terms of macroscopic thermodynamical quantities, like susceptibilities and thermal average values. The quality of the bounds is checked by the exact expressions for a single spin in an external magnetic field. Their usefulness is illustrated by two examples of many-particle models which are exactly solved in the thermodynamic limit: the Dicke superradiance model and the single impurity Kondo model. It is shown that as far as divergent behavior is considered, the fidelity susceptibility and the thermodynamic susceptibility are equivalent for a large class of models exhibiting critical behavior.Comment: 19 page

On the Finite-Temperature Generalization of the C-theorem and the Interplay between Classical and Quantum Fluctuations

The behavior of the finite-temperature C-function, defined by Neto and Fradkin [Nucl. Phys. B {\bf 400}, 525 (1993)], is analyzed within a d -dimensional exactly solvable lattice model, recently proposed by Vojta [Phys. Rev. B {\bf 53}, 710 (1996)], which is of the same universality class as the quantum nonlinear O(n) sigma model in the limit $n\to \infty$. The scaling functions of C for the cases d=1 (absence of long-range order), d=2 (existence of a quantum critical point), d=4 (existence of a line of finite temperature critical points that ends up with a quantum critical point) are derived and analyzed. The locations of regions where C is monotonically increasing (which depend significantly on d) are exactly determined. The results are interpreted within the finite-size scaling theory that has to be modified for d=4. PACS number(s): 05.20.-y, 05.50.+q, 75.10.Hk, 75.10.Jm, 63.70.+h, 05.30-d, 02.30Comment: 15 pages LATEX, ioplppt.sty file used, 6 EPS figures. Some changes made in section V (on finite-size scaling interpretation of the results obtained

Leydig cell-immune cell interaction: an example of neuroendocrine-immune communication in testis

In her paper "Tilings will never be the same again" Dr Kathleen L. Wishner quoted Alvin Toffler's book Future Shock written in 1970. Toffler defined "future shock" as a time phenomenon, a product of the greatly accelerated change in society. The scientific research itself is a demonstration of this accelerated change. In particular, data systematized by Davidoff et al in this volume of Biomedical Reviews indicate the change in the understanding of the nature and origin of Leydig cells of the human testis.Biomedical Reviews 1996; 6: 1-4

A suggestive neurotrophic potential of mast cells in heart and submandibular glands of the rat

According to the neurotrophic theory, the nerve growth factor (NGF) is widely distributed in the effector tissues of peripheral sympathetic and sensory neurons, suggesting that the density of innervation is controlled by effector derived NGF. Sympathetic neurons require access to NGF for survival throughout life, whereas sensory neurons are dependent on NGF only during restricted period of embryonic development. This development-related feature of sympathetic neurons suggests that they crucially depend on plasticity of NGF biology, including secretion, availability, and utilization, to maintain appropriate neuronal function in adult life, and even in old age. While most previous studies on the cellular source of NGF have focused on neuronal and nonneuronal effector cells, it was recently demonstrated that NGF secretion is not only restricted to cells receiving a direct innervation. Immune cells, including mast cells (MC), lymphocytes and macrophages, for example, produce and release NGF as well as NGF secretion-inducing cytokines. Likewise, since the first evidence that NGF treatment causes a significant increase in the number and size of MC has been published by Aloe and Levi-Montalcini in 1977, it has been repeatedly shown that these cells are also NGF-responsive cells, thus providing further evidence for a widely investigated MC-nerve interaction. Further on this trophobiological line, a positive correlation of the amount of NGF and expression of NGF mRNA with the density of sympathetic innervation was demonstrated in a variety of organs. In the rat heart, one such example, the atrium contains a higher amount of NGF corresponding to a denser sympathetic nerve supply compared to the ventricle. Such a correlation was also revealed in the submandibular glands (SMG) and iris. Likewise, the density of MC in the ankle joint capsule, which is heavily innervated, is greater than in the capsule of the knee, which is less densely innervated, and the MC number in the synovial joint of spontaneously hypertensive rats, which have increased sympathetic nerve supply, is significantly greater than in normotensive rats. A summing-up of the above mentioned data shows that (i) MC are NGF secreting/responsive cells and frequently colocalized with nerves, and (ii) a higher NGF amount correlates with a denser sympathetic innervation of a tissue . This, in our eyes, brings into question the sole contribution of the "classical" effector cells to neurotrophic support of sympathetic nerve-innervated tissues. Consequently, we suggest that MC, through their own and/or cytokine-induced NGF secretion, may also be implicated in the neurotrophic potential in these tissues.Biomedical Reviews 1998; 9: 143-145

Estimation of errors in text and data processing

The company Adiss Lab Lts. obtained 1 000 000 medical reports that are either in free form text, or in XML format. One of the main goals of their development is to integrate an algorithm for information extraction (IE) in their platform. The verification of the algorithm’s output for a report is done by a medical doctor (MD) for a certain fee. Validating the correctness of all data would be overwhelming and very expensive. Hence, the problem, as presented by the company, is to provide a method (algorithm) which determines the minimum amount of reports that will validate the correctness of the IE algorithm and a procedure for selecting these reports. In order to solve the problem we have considered an algorithm-centric approach uses active learning and semi-supervised learning

Neutral-current neutrino cross section and expected supernova signals for 40^{40}Ar from a three-fold increase in the magnetic dipole strength

In view of the great interest in liquid argon neutrino detectors, the $^{40}$Ar($\gamma,\gamma'$)$^{40}$Ar$^{*}$ reaction was revisited to guide a calculation of the neutral current neutrino cross section at supernova energies. Using the nuclear resonance fluorescence technique with a monoenergetic, 99% linearly polarized photon beam, we report a three-fold increase in magnetic dipole strength at around 10 MeV in $^{40}$Ar. Based on shell-model calculations, and using the experimentally identified transitions, the neutral current neutrino cross sections for low-energy reactions on $^{40}$Ar are calculated

Quantum critical scaling and the Gross-Neveu model in 2+1 dimensions

The quantum critical behavior of the 2+1 dimensional Gross--Neveu model in the vicinity of its zero temperature critical point is considered. The model is known to be renormalisable in the large $N$ limit, which offers the possibility to obtain expressions for various thermodynamic functions in closed form. We have used the concept of finite--size scaling to extract information about the leading temperature behavior of the free energy and the mass term, defined by the fermionic condensate and determined the crossover lines in the coupling (\g) -- temperature ($T$) plane. These are given by T\sim|\g-\g_c|, where \g_c denotes the critical coupling at zero temperature. According to our analysis no spontaneous symmetry breaking survives at finite temperature. We have found that the leading temperature behavior of the fermionic condensate is proportional to the temperature with the critical amplitude $\frac{\sqrt{5}}3\pi$. The scaling function of the singular part of the free energy is found to exhibit a maximum at $\frac{\ln2}{2\pi}$ corresponding to one of the crossover lines. The critical amplitude of the singular part of the free energy is given by the universal number $\frac13[\frac1{2\pi}\zeta(3)-\mathrm{Cl}_2(\frac{\pi}3)]=-0.274543...$, where $\zeta(z)$ and $\mathrm{Cl}_2(z)$ are the Riemann zeta and Clausen's functions, respectively. Interpreted in terms the thermodynamic Casimir effect, this result implies an attractive Casimir "force". This study is expected to be useful in shedding light on a broader class of four fermionic models.Comment: 6 pages, 3 figure