Search Results - (Author, Cooperation:Sassi)

1525-1314

Blackwell Publishing Journal Backfiles 1879-2005

Geosciences

Chemical data for 139 natural paragonite-muscovite (Pg-Ms) pairs illustrate the effects of ferromagnesian components on the P-T-X topology of the Pg-Ms solvus. The pairs were selected on the basis of: reasonably accurate knowledge of the P-T conditions of formation; evidence for close approach to equilibrium at peak metamorphic conditions; exclusion of pairs in which paragonite contains more than 5 mol% margarite; and exclusion of pairs from polymetamorphic rocks that contain more than one set of cogenetic Pg-Ms pairs. Graphical analysis reveals considerable scatter in the data; nevertheless, it is evident that the muscovite limb of the solvus shifts markedly toward end-member muscovite with increasing pressure from approximately 7 kbar to 21 kbar. This shift is attributed to a pressure-induced increase of the ferromagnesian content of muscovite, which increases the size of the XII alkali site - to the effect that K is more readily accommodated than Na. The data also suggest that the paragonite limb of the solvus migrates slightly toward end-member paragonite with increasing pressure. Broadening of the Pg-Ms solvus with increasing pressure reflects increasingly nonideal Na-K mixing as the phengite content of muscovite increases. Due to the wide scatter of data for Pg-phengitic-Ms pairs, it is concluded that, at the present time, Pg-Ms solvus thermometry is only viable for quasibinary Pg-Ms pairs.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Monte Carlo simulation has been used to study the configurational properties of a lattice-model isolated polyelectrolyte with attractive segment–segment interaction potentials. This model provides a simple representation of a hydrophobic polyelectrolyte. Configurational properties were investigated as a function of chain ionization, Debye screening length, and segment–segment potential. For chains with highly attractive segment–segment potentials (i.e., hydrophobic chains), large, global changes in polymer dimensions were observed with increasing ionization. The transformation from a collapsed chain at low ionization to an expanded chain at high ionization becomes increasingly sharp (i.e., occurs over a smaller range of ionization) with increasing chain hydrophobicity. The ionization-induced structural transitions for this model hydrophobic polyelectrolyte are analogous to pH-induced transitions seen in real polyelectrolytes and gels. These studies suggest a simple explanation for such transitions based on competing hydrophilic and hydrophobic interactions.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Monte Carlo simulation has been used to study titration and configurational properties of an isolated hydrophobic polymer containing weakly-ionizable groups. Using a cubic lattice, simulations were performed in the grand canonical ensemble to include the effect of the local charge environment on the ionization of weak electrolyte segments. Properties were studied as a function of polymer hydrophobicity, fraction of ionizable segments, solution ionic strength, and pH. The polymer segments experienced three types of competing interaction: excluded volume, attractive nearest-neighbor forces which account for the net balance of segment–segment, segment–solvent, and solvent–solvent interactions, and long-range electrostatic forces between ionized segments, calculated with a screened Debye–Hückel potential. Simulations show that the model chain expands with chain ionization, which depends on solution pH. As the chain becomes increasingly charged, the ionization process becomes more difficult because of rising local charge density around the ionizable segments. The effect of rising local charge density increases for larger fractions of ionizable groups, with increased hydrophobicity and with low ionic strength.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

The frequency of seven rovibrational transitions in the ν3 band, Q branch of 188OsO4 have been measured with high accuracy. The spectrometer used consists of two CO2 lasers [∼3 W on the 10R(0)], the first of which is stabilized on the 4.3 μm fluorescence Lamb dip of the CO2 and the second on the saturated absorption dip of the rovibrational transitions of 188OsO4. The OsO4 transition frequencies are obtained combining the known frequency of the first laser with the measured frequency of the beat note between the two laser beams. For the assignment of the transitions the recent Fourier transform analysis by Bobin et al. [J. Mol. Spectrosc. 122, 229 (1987)] was used. The access to the 10R(0) laser line has made it possible to investigate, for the first time, the Q branch of the ν3 band of OsO4 in a sub-Doppler regime. Furthermore, the tetrahedral fine structure in the ground and in the ν3 state has been analyzed using the infrared–radio frequency double resonance technique. The tetrahedral splitting constants, Dt for the ground state and Z3t for the ν3 state, have been calculated with higher accuracy than in previous works.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Monte Carlo simulations were performed to obtain the distribution of charged segments around the center of mass in a lattice-model, isolated weak polyelectrolyte with attractive segment–segment (hydrophobic) interactions. The charge distribution (relative to the mean ionization for a given state) is shown to depend essentially on chain conformation (stiffness).

Electronic Resource

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Radiation-induced fibrosis is a common side-effect of cancer treatment. The pathophysiological events leading to fibrosis are not known in detail. We analysed the effect of therapeutic irradiation on human skin collagen synthesis, skin thickness, gelatinases and their inhibitors. Twenty randomly chosen women who had been treated for breast cancer with surgery and radiation therapy participated in the study. In each patient, the irradiated skin area was compared with a corresponding non-treated skin area. Suction blister fluid (SBF) and serum samples were analysed for the aminoterminal propeptides of type I and type III procollagens (PINP and PIIINP), tissue inhibitors of matrix metalloproteinases (MMPs) 1 and 2 (TIMP-1 and TIMP-2) and MMP-9 and MMP-2/TIMP-2 complex. Skin biopsies were analysed for PINP and immunohistochemical staining was used for PIIINP. In irradiated skin, PINP, PIIINP, TIMP-1 and MMP-2/TIMP-2 complex levels in SBF and the number of PINP-positive fibroblasts in tissue sections were significantly higher in comparison with non-treated skin. The levels of TIMP-2 in irradiated and non-irradiated skin were similar. MMP-9 could not be detected in SBF with the assay used. The serum levels of MMP-9 were higher in the treated subjects than the reference values. The serum values of PINP, PIIINP, TIMP-1, TIMP-2 and MMP-2/TIMP-2 complex were not significantly affected. These results indicate increased local collagen synthesis and accumulation of connective tissue in irradiated skin. The marked upregulation of collagen synthesis as a result of irradiation offers a possibility to treat this complication with compounds such as topical steroids which downregulate collagen synthesis.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

A multigap cascade solar cell system which incorporates graded composition layers is proposed. The new design adds other useful benefits to the advantages of both cascade systems and graded gap regions. Moreover, the pair generation rate in each cell is a bell-shaped curve and it will be approximated by a normal distribution curve, with the result that the photocurrent will be formally determined. Such a procedure could be of some use even for generical generation rates, as it will be discussed. Efficiencies for 2, 3, and 4 cells will be worked out under AM1.5 solar spectrum and the influence of different air mass conditions will be analyzed. Finally, a comparison of these results with the limiting efficiency of multigap cascade structures will be considered and the presence of a particular intrinsic loss usually not contemplated will be shown.

Electronic Resource

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

1360-0443

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Psychology

Aims  To assess the prevalence of potential alcohol use disorders and associated factors using the Alcohol Use Disorders Identification Test (AUDIT).Design  Cross-sectional study.Setting  A town in southern Brazil.Participants  A representative sample of 1260 people aged 15 and over.Measurements  Demographic, socioeconomic, smoking habit and mental health data were collected. Logistic regression was used in the multivariate analysis, and odds ratios (ORs) and 95% confidence intervals (CIs) were calculated.Findings  Overall prevalence of alcohol use disorder was 7.9%, with 14.5% prevalence among men and 2.4% among women. The risk of alcohol misuse increased across social class (P linear trend = 0.03) and compared with the highest classes (A and B), groups C through E had ORs of 1.48, 1.51 and 2.36, respectively. Males had an OR of 6.89 (CI 3.61–13.16) compared with women. A linear trend was found (P = 0.001) between smoking categories, and smokers (OR 3.27; CI 1.91–5.58) and ex-smokers (OR 1.30; CI 0.56–2.98) were at higher risk than non-smokers. Those with minor psychiatric disorders had a 2.48 OR (CI 1.35–4.56) of presenting a positive test.Conclusions  The AUDIT detected a high prevalence of potential alcohol use disorders in the population sampled. Those identified are potential targets for preventive measures implemented through health policies.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Polarized light scattering experiments in the GHz frequency range (Rayleigh–Brillouin spectra) are reported for liquid acetonitrile. Hypersonic velocities and absorption coefficients have been measured as a function of temperature and of transferred wave vector. The plots of these quantities versus frequency show characteristic dispersion which is indicative of relaxation phenomena. The occurring relaxation has been interpreted as due to a thermal process in which the translational energy of molecules is transferred, during the collisions or through dipolar interactions, into internal degrees of freedom of low quanta vibrational motions. The quite strange behavior of the relaxation time with the temperature has been interpreted and compared with the behavior of the relaxation time in liquid chloroform. © 1998 American Institute of Physics.

Electronic Resource

1442-9993

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Abstract  An important aspect of arid regions is the spatial heterogeneity resulting from differences among plant communities. There are process differences among different vegetation patches increasing variability in the functioning of the ecosystem. The purpose of this study was to estimate granivory, by studying variation of seed removal rates among patches at the local scale and variation according to seed type. We carried out experiments during four seasons in three plant communities in the Monte Desert, Argentina: ‘peladal’, mesquite forest and creosotebush. Seed trays were offered to ants, birds and rodents. Two types of commercial seeds (sunflower and millet) were used. We found that seed removal rate was significantly different among plant communities, among taxa (birds, ants and murid rodents), and among seasons, and that removal rate was higher for sunflower. Seed removal rates by murid rodents were higher than by birds or ants, and occasionally as high as those found in other deserts. The heterogeneity of seed removal patterns at the local level was as strong as that found between continents. Further studies may show similar local heterogeneity in other deserts of the world.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] The recent abundance of genome sequence data has brought an urgent need for systematic proteomics to decipher the encoded protein networks that dictate cellular function. To date, generation of large-scale protein–protein interaction maps has relied on the yeast two-hybrid system, which ...

Electronic Resource

0003-4916

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource

0375-9601

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource

0921-4488

Adjustment factors ; Average daily gain ; Barbarine breed ; Correlations ; Heritability

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Electronic Resource

0003-4916

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource

0003-2697

''enkephalinase'' ; dansyl ; fluorometric assay ; kinetics enzyme ; neuropeptides ; organic synthesis

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Chemistry and Pharmacology

Electronic Resource

0014-4827

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Medicine

Electronic Resource

0012-821X

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Geosciences

Physics

Electronic Resource

0022-4073

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource