On the Path Integral Representation for Spin Systems

We propose a classical constrained Hamiltonian theory for the spin. After the Dirac treatment we show that due to the existence of second class constraints the Dirac brackets of the proposed theory represent the commutation relations for the spin. We show that the corresponding partition function, obtained via the Fadeev-Senjanovic procedure, coincides with the one obtained using coherent states. We also evaluate this partition function for the case of a single spin in a magnetic field.Comment: To be published in J.Phys. A: Math. and Gen. Latex file, 12 page

Low-energy renormalization of the electron dispersion of high-Tc_c superconductors

High-resolution ARPES studies in cuprates have detected low-energy changes in the dispersion and absorption of quasi-particles at low temperatures, in particular, in the superconducting state. Based on a new 1/N expansion of the t-J-Holstein model, which includes collective antiferromagnetic fluctuations already in leading order, we argue that the observed low-energy structures are mainly caused by phonons and not by spin fluctuations, at least, in the optimal and overdoped regime.Comment: 6 pages, 3 figure

Testicular histopathology, semen analysis and FSH, predictive value of sperm retrieval: supportive counseling in case of reoperation after testicular sperm extraction (TESE)

Background: To provide indicators for the likelihood of sperm retrieval in patients undergoing testicular sperm extraction is a major issue in the management of male infertility by TESE. The aim of our study was to determine the impact of different parameters, including testicular histopathology, on sperm retrieval in case of reoperation in patients undergoing testicular sperm extraction. Methods: We retrospectively analyzed 486 patients who underwent sperm extraction for intracytoplasmic sperm injection and testicular biopsy. Histology was classified into: normal spermatogenesis; hypospermatogenesis (reduction in the number of normal spermatogenetic cells); maturation arrest (absence of the later stages of spermatogenesis); and Sertoli cell only (absence of germ cells). Semen analysis and serum FSH, LH and testosterone were measured. Results: Four hundred thirty patients had non obstructive azoospermia, 53 severe oligozoospermia and 3 necrozoospermia. There were 307 (63%) successful sperm retrieval. Higher testicular volume, lower levels of FSH, and better histological features were predictive for sperm retrieval. The same parameters and younger age were predictive factors for shorter time for sperm recovery. After multivariable analysis, younger age, better semen parameters, better histological features and lower values of FSH remained predictive for shorter time for sperm retrieval while better semen and histology remained predictive factors for successful sperm retrieval. The predictive capacity of a score obtained by summing the points assigned for selected predictors (1 point for Sertoli cell only, 0.33 points for azoospermia, 0.004 points for each FSH mIU/ml) gave an area under the ROC curve of 0.843. Conclusions: This model can help the practitioner with counseling infertile men by reliably predicting the chance of obtaining spermatozoa with testicular sperm extraction when a repeat attempt is planne

ARPES kink is a "smoking gun" for the theory of high-Tc superconductors: dominance of the electron-phonon interaction with forward scattering peak

The ARPES spectra in high-Tc superconductors show four distinctive features in the quasiparticle self-energy. All of them can be explained consistently by the theory in which the electron phonon interaction (EPI) with the forward scattering peak dominates over the Coulomb scattering. In particular, this theory explains why there is no shift of the nodal kink at 70 meV in the superconducting state, contrary to the clear shift of the anti-nodal singularity at 40 meV. The theory predicts a ``knee''-like structure of the imaginary part of the self-energy, which is phonon dominated for $\omega \approx \omega^{(70)}_{ph}$, and shows linear behavior for $\omega > \omega^{(70)}_{ph}$ - due to the Coulomb scattering. Recent ARPES spectra give that the EPI coupling constant is much larger than the Coulomb one. The dip-hump structure in the spectral function comes out naturally from the proposed theory.Comment: 5 pages, 3 figure

Sudden hearing loss as an early detector of multiple sclerosis: a systematic review

To evaluate whether Sudden Sensorineural Hearing Loss (S-SNHL) may be an early symptom of Multiple Sclerosis (MS). A systematic review was conducted using the following keywords: "Multiple sclerosis, hearing loss, sudden hearing loss, vertigo, tinnitus, magnetic resonance imaging, otoacoustic emission, auditory brainstem responses, white matter lesions, sensorineural hearing loss, symptoms of MS and otolaryngology, nerve disease and MS". Only the articles that included results of at least one auditory test and MRI were considered. We evaluated the prevalence of SNHL in patients with MS, the presence of different forms of SNHL (S-SNHL and Progressive SNHL (P-SNHL)) and their correlation with the stage of MS, the results of electrophysiological tests, and the location (if any) of MS lesions as detected by white matter hyperintensities in the MRI. We reviewed a total of 47 articles, which included 29 case reports, 6 prospective studies, 6 cohort studies, 4 case-control studies, and 2 retrospective studies. 25% of patients suffered from SNHL. S-SNHL typically occurred in the early stage of the disease (92% of patients) and was the only presenting symptom in 43% of female subjects. Instead, P-SNHL occurred in the late stage of MS (88% of patients). Auditory Brainstem Responses (ABR) were abnormal in all MS patients with S-SNHL. When S-SNHL appeared during the early stage of the disease, MS lesions were found in the brain in 60% of patients and in the Internal Auditory Canal in 40% of patients. ABR remained abnormal after recovery. S-SNHL can be an early manifestation of MS and should always be considered in the differential diagnosis of this condition, especially in women. The pathophysiology can be explained by the involvement of microglia attacking the central and/or peripheral auditory pathways as indicated by WMHs

Sinonasal angioleiomyoma with adipocyte differentiation: clinicopathologic study of 2 cases and review of the literature

Angioleiomyoma (ALM) is a benign tumor of the skin and soft tissues composed of well differentiated smooth muscle cells arranged around and among many vascular channels. Few cases have been reported in the sinonasal region, where ALM may show a variable amount of mature adipose tissue that may make hard the distinction from angiomyolipoma. We report here two cases that presented with a three- and six-month history of left nasal obstruction respectively. In both patients, clinical examination and imaging studies failed to reveal features of tuberous sclerosis complex and demonstrated a mass obliterating the nasal cavity arising from the inferior turbinate. Both masses were endoscopically excised. Pathologic analysis revealed highly vascularized tumors composed of well differentiated smooth muscle cells intermingled with a variable number of mature adipocytes. Immunostaining for melanocytic markers was negative. Based on these findings, both tumors were diagnosed as sinonasal-ALM with adipocytic differentiation. These two cases indicate that both clinical data (i.e. absence of features of tuberous sclerosis complex) and immunohistochemistry (i.e. absence of melanocytic markers) are mandatory for the recognition of sinonasal-ALM with adipocytic differentiation. The term angiomyolipoma to identify these lesions is confusing and should be abandoned