Gender-Specific Protection from Microvessel Rarefaction in Female Hypertensive Rats

Epidemiologic studies reveal that women have a significantly lower age-adjusted morbidity and mortality from cardiovascular disease than men, suggesting that gender is a cardiovascular disease risk factor. The mechanism of the “gender protection” is unknown. In this study, we investigated the microvascular remodeling in reduced renal mass plus a high salt (4.0% NaCl) diet model of hypertension (RRM + HS). We hypothesized that women would be protected from the increase in blood pressure and from the microvascular rarefaction associated with RRM + HS hypertension. Studies were designed to determine whether female rats were less susceptible to changes in microvessel density during RRM + HS. Microvessel density was measured in male and female low salt (0.4% LS) sham-operated controls (Sham + LS) and after 3 days or 4 weeks of RRM + HS hypertension. The microcirculation of hind limb (medial and lateral gastrocnemius, plantaris, soleus) muscles was visualized using rhodamine-labeled Griffonia simplicifolia I lectin. Tissue sections were examined by videomicroscopy and microvessel density was determined by quantitative stereology. As shown previously, mean arterial pressure increased to 160 ± 8 mm Hg and microvessel density decreased (\u3e30% decrease in all beds) in male RRM + HS. In contrast, mean arterial pressure of female RRM + HS rats was modestly increased from 101 ± 2 to 118 ± 4 mm Hg. Despite previous results showing a reduction in microvessel density of both normotensive and hypertensive male rats on a high salt diet, microvessel density of female RRM + HS rats was not reduced at either time. These results suggest that gender protection in the RRM rat extends beyond an attenuation of the increase in pressure to an immunity from microvascular rarefaction

Scattering of rare-gas atoms at a metal surface: evidence of anticorrugation of the helium-atom potential-energy surface and the surface electron density

Recent measurements of the scattering of He and Ne atoms at Rh(110) suggest that these two rare-gas atoms measure a qualitatively different surface corrugation: While Ne atom scattering seemingly reflects the electron-density undulation of the substrate surface, the scattering potential of He atoms appears to be anticorrugated. An understanding of this perplexing result is lacking. In this paper we present density functional theory calculations of the interaction potentials of He and Ne with Rh(110). We find that, and explain why, the nature of the interaction of the two probe particles is qualitatively different, which implies that the topographies of their scattering potentials are indeed anticorrugated.Comment: RevTeX, 4 pages, 10 figure

From a kinetic equation to a diffusion under an anomalous scaling

A linear Boltzmann equation is interpreted as the forward equation for the probability density of a Markov process (K(t), i(t), Y(t)), where (K(t), i(t)) is an autonomous reversible jump process, with waiting times between two jumps with finite expectation value but infinite variance, and Y(t) is an additive functional of K(t). We prove that under an anomalous rescaling Y converges in distribution to a two-dimensional Brownian motion. As a consequence, the appropriately rescaled solution of the Boltzmann equation converges to a diffusion equation

2-(3-Cyanopropyldimethylsilyl)ethyl as a Polar Sulfur Protecting Group

Organosulfur compounds are ubiquitous in synthetic chemistry, biology and materials chemistry. The reactivity of free sulfhydryls requires their masking in many synthetic strategies. To facilitate the isolation of protected thiols by chromatography, we propose 2-(3-cyanopropyldimethylsilyl)ethyl as a polar protecting group analogue of 2-(trimethylsilyl)ethyl. The masked thiophenol is obtained in two synthetically complementing ways. Either an existing thiophenol is protected, or the protected thiol group is introduced by a cross-coupling reaction. In both cases the required reagents are readily available from inexpensive starting materials. Thiol protection and thiol introduction both tolerate a large variety of functional groups and substitution patterns, and the protected thiophenols are stable toward a broad range of reaction conditions. The stability of the protected derivatives in cross-coupling reactions and the mild reaction conditions for the release of the protecting group further emphasizes the potential of the methodology

The clustered universe : het geclusterde heelal

In this PhD thesis, I describe work done in the CosmoGrid and AMUSE projects. CosmoGrid is a _CDM N-body simulation containing 8.5 billion dark matter particles within a volume of only (30 Mpc)^3, resulting in very high mass resolution. In order to run such a large simulation, we investigate a method of combining multiple supercomputers via a fast network; combining them into one large machine for the final calculation. We compare the results of CosmoGrid to previous _CDM simulations, and use the finalised CosmoGrid data to investigate how an aligned group of galaxies in a void region might have formed. Combining CosmoGrid with the Astrophysical Multipurpose Software Environment (AMUSE), we investigate a method to embed simulated star clusters in a large-scale environment such as a dark matter halo. Finally, we use this method to run self-consistent simulations of open star clusters embedded in a forming Milky Way-like galaxy.NWO grant #643.000.803, Leids Kerkhoven-Bosscha FondsUBL - phd migration 201

The formation of young massive clusters by colliding flows

Young massive clusters (YMCs) are the most intense regions of star formation in galaxies. Formulating a model for YMC formation whilst at the same time meeting the constraints from observations is highly challenging however. We show that forming YMCs requires clouds with densities $\gtrsim$ 100 cm$^{-3}$ to collide with high velocities ($\gtrsim$ 20 km s$^{-1}$). We present the first simulations which, starting from moderate cloud densities of $\sim100$ cm$^{-3}$, are able to convert a large amount of mass into stars over a time period of around 1 Myr, to produce dense massive clusters similar to those observed. Such conditions are commonplace in more extreme environments, where YMCs are common, but atypical for our Galaxy, where YMCs are rare.Comment: 6 pages, 5 figures, accepted for publication in MNRAS Letter

Site determination and thermally assisted tunneling in homogenous nucleation

A combined low-temperature scanning tunneling microscopy and density functional theory study on the binding and diffusion of copper monomers, dimers, and trimers adsorbed on Cu(111) is presented. Whereas atoms in trimers are found in fcc sites only, monomers as well as atoms in dimers can occupy the stable fcc as well as the metastable hcp site. In fact the dimer fcc-hcp configuration was found to be only 1.3 meV less favorable with respect to the fcc-fcc configuration. This enables a confined intra-cell dimer motion, which at temperatures below 5 K is dominated by thermally assisted tunneling.Comment: 4 pages, 4 figure

Comment on "A centrosome-independent role for gamma-TuRC proteins in the spindle assembly checkpoint"

Müller et al. (Reports, 27 October 2006, p. 654) showed that inhibition of the γ-tubulin ring complex (γ-TuRC) activates the spindle assembly checkpoint (SAC), which led them to suggest that γ-TuRC proteins play molecular roles in SAC activation. Because γ-TuRC inhibition leads to pleiotropic spindle defects, which are well known to activate kinetochore-derived checkpoint signaling, we believe that this conclusion is premature

A platform independent communication library for distributed computing

We present MPWide, a platform independent communication library for performing message passing between supercomputers. Our library couples several local MPI applications through a long distance network using, for example, optical links. The implementation is deliberately kept light-weight, platform independent and the library can be installed and used without administrative privileges. The only requirements are a C++ compiler and at least one open port to a wide area network on each site. In this paper we present the library, describe the user interface, present performance tests and apply MPWide in a large scale cosmological N-body simulation on a network of two computers, one in Amsterdam and the other in Tokyo