Preparation of Isolated Blood Capillaries

Blood capillaries have been isolated from various tissue sources yielding suspensions of capillary segments. These have provided opportunities to study the cellular properties of capillary endothelium under conditions uncomplicated by the presence of stromal tissues and in which measured parameters can be attributed to endothelial cells. Fresh capillary isolates have been used directly as experimental systems but the yield of endothelium is quite low. Amplification of endothelial biomass has been accomplished by using freshly isolated capillaries as explants for primary tissue culture. It has not been previously possible, however, to obtain large amounts of capillary endothelium from a single preparation nor have different capillary types been isolated from the same tissue. The rete mirabile of the eel swim bladder is a copious source of capillaries of two types: thick-walled, continuous capillaries heavily invested with pericytes and thin-walled, fenestrated capillaries. These can be isolated in large numbers free of large blood vessels and contaminating stromal tissue. The two types of capillaries can be isolated from each other by perfusing magnetic beads into one type prior to isolation and separating them from the other type in a magnetic field. This provides a system in which the cellular properties of the two types of endothelium can be studied in vitro and, due to a common isolation procedure, direct comparisons can be made

Nonlocal Effects on the Magnetic Penetration Depth in d-wave Superconductors

We show that, under certain conditions, the low temperature behavior of the magnetic penetration depth $\lambda(T)$ of a pure d-wave superconductor is determined by nonlocal electrodynamics and, contrary to the general belief, the deviation $\Delta\lambda(T) = \lambda(T)-\lambda(0)$ is proportional to T^2 and not T. We predict that the $\Delta\lambda(T)\propto T^2$ dependence, due to nonlocality, should be observable experimentally in nominally clean high-T_c superconductors below a crossover temperature $T^* = (\xi_o/\lambda_o)\Delta_o \sim 1 K$. Possible complications due to impurities, surface quality and crystal axes orientation are discussed.Comment: REVTeX3.0; 4 pages, 1 EPS figure (included); Submitted to Phys. Rev. Let

USPIO-enhanced magnetic resonance imaging of the knee in asymptomatic volunteers

The aim of this study was to compare signal characteristics of the synovium in knees of asymptomatic volunteers before and after intravenous administration of ultrasmall superparamagnetic iron oxide particles (USPIO). Ten knees of 10 asymptomatic volunteers were examined before and 36h after intravenous administration of USPIO on a 1.5-T MR system using T1-weighted spin-echo, T2-weighted fast spin-echo, T2*-weighted gradient-echo (GRE), and short inversion time inversion-recovery sequences. In addition, synovial perfusion was measured using Gd-enhanced GRE imaging during the first imaging session. Images were analyzed qualitatively for any visual changes before and after USPIO administration. Signal-to-noise ratios (SNR) of the synovium were determined on unenhanced and USPIO-enhanced sequences. All MR images were reviewed for presence of any degenerative changes. Qualitative image analysis revealed no visually detectable changes of any knee joint before and after USPIO administration. The SNR values of the synovium on T1w, T2w, and T2*w images before and after USPIO administration showed no significant difference (T1, P = 0.86; T2, P = 0.95; T2*, P = 0.86). None of the volunteers showed any relevant degenerative changes of the knee and synovial perfusion was within normal limits. In knees of asymptomatic volunteers without any relevant degenerative changes and normal synovial perfusion neither visual changes nor changes of SNR values of the synovium can be depicted after USPIO administration. This means that USPIO-enhanced MRI may be used for assessment of knee disorders with increased macrophage activit

Aqueous Black Colloids of Reticular Nanostructured Gold

Since ancient times, noble gold has continuously contributed to several aspects of life from medicine to electronics. It perpetually reveals its new features. We report the finding of a unique form of gold, reticular nanostructured gold (RNG), as an aqueous black colloid, for which we present a one-step synthesis. The reticules consist of gold crystals that interconnect to form compact strands. RNG exhibits high conductivity and low reflection and these features, coupled with the high specific surface area of the material, could prove valuable for applications in electronics and catalysis. Due to high absorption throughout the visible and infrared domain, RNG has the potential to be applied in the construction of sensitive solar cells or as a substrate for Raman spectroscopy

Roots of the derivative of the Riemann zeta function and of characteristic polynomials

We investigate the horizontal distribution of zeros of the derivative of the Riemann zeta function and compare this to the radial distribution of zeros of the derivative of the characteristic polynomial of a random unitary matrix. Both cases show a surprising bimodal distribution which has yet to be explained. We show by example that the bimodality is a general phenomenon. For the unitary matrix case we prove a conjecture of Mezzadri concerning the leading order behavior, and we show that the same follows from the random matrix conjectures for the zeros of the zeta function.Comment: 24 pages, 6 figure

Estimating the Sex Composition of the Summer Flounder Catch using Fishery-Independent Data

Models that account for sex-specific behavior and population dynamics are becoming more common in the stock assessment of sexually dimorphic fishes. However, such models can be data intensive and require some knowledge or assumptions about the sex ratio of fishery landings. A recent stock assessment review of Summer Flounder Paralichthys dentatus identified the need to account for sex-specific fishing mortality in the assessment model; however, no data on the sex composition of the catch were available. Fishery-independent, sex-specific information for this species is collected annually by the National Marine Fisheries Service\u27s Northeast Fisheries Science Center during their bottom trawl survey. Sex at age from the survey could be applied to the fishery landings if the probability of landing a given sex at a given age is equivalent for fish collected by the survey and those in the landings. To generate the first regionally comprehensive database on the sex ratio of Summer Flounder landings and to determine the efficacy of using survey sex-at-age keys to estimate the sex of landed fish, we recorded the sex composition of the commercial and recreational catches of Summer Flounder (n = 31,912) in 2010 and 2011. When (1) trawl survey length data were left-truncated to simulate the minimum retention sizes in the fisheries and (2) age-length keys generated from fishery-dependent data were applied to length frequency distributions from the survey to simulate the growth rates of landed fish, the sex-at-age pattern in the survey-derived data closely resembled the patterns in the catch. However, statistically significant differences in sex at age remained between the catch and the survey-derived data. We hypothesize that these differences are attributable to differences in the spatiotemporal distributions of the sexes and of the survey and fishing effort

Risk Assessment to the Health of Amazonian Indigenous For the Consumption of Fish, Meat of Hunts and Vegetables Containing Metylmercury

This study was to evaluate the exposure to methylmercury (HgMe) and the potential health risk of Tupari Indians through the consumption of their main foods. Were collection of samples of plant foods and muscle tissue from different species of fish and wild animals consumed in three villages of the Rio Branco Indigenous Land in Rondônia, in the Brazilian Amazon. The HgMe was measured in an atomic fluorescence spectrophotometer with gas chromatography. The statistical treatment of the data was performed by software R. Of the six different plant species, only sweet potato (Ipomoea batatas) had mean concentrations of HgMe above the limit of detection of the analytical technique for the three villages. There was a significant difference in the levels of HgMe between the species of wild animals and fish belonging to the same alimentary habit. Carnivores presented higher levels of HgMe than those obtained for non-predators, both for fish and for wild animals. The results of the assessment of the potential risk to indigenous health indicated a total HgMe of the weekly ingestion rate (WIR) of between 8.4 and 15.0 μg / kg of body weight for the villages evaluated, extrapolating all reference doses ( RfD) regarding for the Provisional Tolerable Weekly Intake (PTWI). The risk quotients (RQ) varied from 5.3 to 21.4, considerably exceeding the limit (RQ ≤ 1), which allows to consider the impossibility of toxic effects of HgMe. The fishes accounted for the highest percentage of WIR of HgMe for all villages, with an emphasis on predatory species. Considering the nutritional value of fish meat, it is suggested the continuity of the consumption of this meat in the villages with preference for non-carnivores

Dynamical Properties of small Polarons

On the basis of the two-site polaron problem, which we solve by exact diagonalization, we analyse the spectral properties of polaronic systems in view of discerning localized from itinerant polarons and bound polaron pairs from an ensemble of single polarons. The corresponding experimental techniques for that concern photoemission and inverse photoemission spectroscopy. The evolution of the density of states as a function of concentration of charge carriers and strength of the electron-phonon interaction clearly shows the opening up of a gap between single polaronic and bi-polaronic states, in analogy to the Hubbard problem for strongly correlated electron systems. The crossover regime between adiabatic and anti-adiabatic small polarons is triggered by two characteristic time scales: the renormalized electron hopping rate and the renormalized vibrational frequency becoming equal. This crossover regime is then characterized by temporarily alternating self- localization and delocalization of the charge carriers which is accompanied by phase slips in the charge and molecular deformation oscillations and ultimately leads to a dephasing between these two dynamical components of the polaron problem. We visualize these features by a study of the temporal evolution of the charge redistribution and the change in molecular deformations. The spectral and dynamical properties of polarons discussed here are beyond the applicability of the standard Lang Firsov approach to the polaron problem.Comment: 31 pages and 23 figs.(eps), accepted in the Phys. Rev.