Características Estereológicas del Hígado de Rata (Rattus norvergicus) sometidas a Menopausia Inducida por Ovariectomía

Trujillo, E (reprint author), Univ Talca, Univ La Frontera, Lircay S-N, Talca, Chile.During menopause, hormonal changes such as decreased estradiol and increased follicle stimulating and luteinizing hormones occur. In premenopausal women fibrosis and hepatic steatosis is less than in postmenopausal women and improves when hormone replacement therapy is administered. The aim of this study was to determine quantitative aspects of the liver of rats undergoing an experimental model of ovariectomy-induced menopause. We used 10 Sprague-Dawley (Rattus norvergicus) healthy adults. The rats were weighed and divided into two groups (bilateral oophorectomy = Group Ovx and control = Group Sham). The animals were sacrificed at 60 days and the liver removed, obtaining a piece of each liver. Five cuts were made of 4 microns and stained with HE. We analyzed five fields per slide. M42 test was used. Stereo logical parameters considered were as follows: Nv, Vv, Sv and total number (Tn) of hepatocytes and sinusoids. The average weight of Ovx and Sham group was 300.8 g and 285.8 g, respectively. The Nv of hepatocytes of rats subjected to sham surgery (CS) and Ovx (CO) was 6.89 and 7.70 x 10(5)/mm(3) x 10(5)/mm(3), respectively. The Vv of CS and CO hepatocytes was 71.92% and 80.48%, respectively. SV and CO, CS hepatocytes was 260.61mm(2)/mm(3) and 273.64 mm(2)/mm(3), respectively. The average volume of CS livers was 8.40 mm(3) and hepatocyte Tn averaged 5.79 x 10(6). The average volume was 9.28 mm(3) CO livers and Tn of 7.15 x 10(6). Regarding the sinusoids, the Nv in the liver CS and CO was 2.81 x 10(5)/mm(3) and 2.64 x 10(5)/mm(3), respectively. The Vv of sinusoids in CS and CO was 16.74% and 16.46%, respectively. The sinusoids in rats Sv CS and CO was 49.40 mm(2)/mm(3) and 45.21 mm(2)/mm(3), respectively. The sinusoids Tn CS and CO averaged 2.37 x 10(6) and 2.45 x 10(6), respectively. The lack of estrogen can cause fibrosis and hepatic steatosis as noted by other authors, but also changes in the organization and the proportion of the components of the liver, factors to consider during diagnosis and prognosis of liver disorders

Dissipative Dynamics of Collisionless Nonlinear Alfven Wave Trains

The nonlinear dynamics of collisionless Alfven trains, including resonant particle effects is studied using the kinetic nonlinear Schroedinger (KNLS) equation model. Numerical solutions of the KNLS reveal the dynamics of Alfven waves to be sensitive to the sense of polarization as well as the angle of propagation with respect to the ambient magnetic field. The combined effects of both wave nonlinearity and Landau damping result in the evolutionary formation of stationaryOA S- and arc-polarized directional and rotational discontinuities. These waveforms are freqently observed in the interplanetary plasma.Comment: REVTeX, 6 pages (including 5 figures). This and other papers may be found at http://sdphpd.ucsd.edu/~medvedev/papers.htm

Followup Observations of SDSS and CRTS Candidate Cataclysmic Variables

We present photometry of 11 and spectroscopy of 35 potential cataclysmic variables from the Sloan Digital Sky Survey, the Catalina Real-Time Transient Survey and vsnet-alerts. The photometry results include quasi-periodic oscillations during the decline of V1363 Cyg, nightly accretion changes in the likely Polar (AM Herculis binary) SDSS J1344+20, eclipses in SDSS J2141+05 with an orbital period of 76+/-2 min, and possible eclipses in SDSS J2158+09 at an orbital period near 100 min. Time-resolved spectra reveal short orbital periods near 80 min for SDSS J0206+20, 85 min for SDSS J1502+33, and near 100 min for CSS J0015+26, RXS J0150+37, SDSS J1132+62, SDSS J2154+15 and SDSS J2158+09. The prominent HeII line and velocity amplitude of SDSS J2154+15 are consistent with a Polar nature for this object, while the lack of this line and a low velocity amplitude argue against this classification for RXS J0150+37. Single spectra of 10 objects were obtained near outburst and the rest near quiescence, confirming the dwarf novae nature of these objects.Comment: 34 pages, 14 figures, in press at A

Fermion localization on a split brane

In this work we analyze the localization of fermions on a brane embedded in five-dimensional, warped and non-warped, space-time. In both cases we use the same nonlinear theoretical model with a non-polynomial potential featuring a self-interacting scalar field whose minimum energy solution is a soliton (a kink) which can be continuously deformed into a two-kink. Thus a single brane splits into two branes. The behavior of spin 1/2 fermions wavefunctions on the split brane depends on the coupling of fermions to the scalar field and on the geometry of the space-time.Comment: 17 pages, 6 figure

Twisted topological structures related to M-branes

Studying the M-branes leads us naturally to new structures that we call Membrane-, Membrane^c-, String^K(Z,3)- and Fivebrane^K(Z,4)-structures, which we show can also have twisted counterparts. We study some of their basic properties, highlight analogies with structures associated with lower levels of the Whitehead tower of the orthogonal group, and demonstrate the relations to M-branes.Comment: 17 pages, title changed on referee's request, minor changes to improve presentation, typos correcte

A search for rapidly pulsating hot subdwarf stars in the GALEX survey

NASA's Galaxy Evolution Explorer (GALEX) provided near- and far-UV observations for approximately 77 percent of the sky over a ten-year period; however, the data reduction pipeline initially only released single NUV and FUV images to the community. The recently released Python module gPhoton changes this, allowing calibrated time-series aperture photometry to be extracted easily from the raw GALEX data set. Here we use gPhoton to generate light curves for all hot subdwarf B (sdB) stars that were observed by GALEX, with the intention of identifying short-period, p-mode pulsations. We find that the spacecraft's short visit durations, uneven gaps between visits, and dither pattern make the detection of hot subdwarf pulsations difficult. Nonetheless, we detect UV variations in four previously known pulsating targets and report their UV pulsation amplitudes and frequencies. Additionally, we find that several other sdB targets not previously known to vary show promising signals in their periodograms. Using optical follow-up photometry with the Skynet Robotic Telescope Network, we confirm p-mode pulsations in one of these targets, LAMOST J082517.99+113106.3, and report it as the most recent addition to the sdBVr class of variable stars.Comment: 11 Pages, 8 Figures, Accepted for publication in the Astrophysical Journa

Influence functions for a hysteretic deformable mirror with a high-density 2D array of actuators

We present modeling and analysis of a hysteretic deformable mirror where the facesheet interacts with a continuous layer of piezoelectric material that can be actuated distributively by a matrix of electrodes through multiplexing. Moreover, a method for calculating the actuator influence functions is described considering the particular arrangement of electrodes. The results are presented in a semi-analytical model to describe the facesheet's deformation caused by a high density array of actuators, and validated in a simulation. The proposed modeling of an interconnection layout of electrodes is used to determine the optimal pressures the actuators have to exert for achieving a desired surface deformation