Formation of cluster crystals in an ultra-soft potential model on a spherical surface

We investigate the formation of cluster crystals with multiply occupied lattice sites on a spherical surface in systems of ultra-soft particles interacting via repulsive, bounded pair potentials. Not all interactions of this kind lead to clustering: we generalize the criterion devised in C. N. Likos et al., Phys. Rev. E, 2001, 63, 031206 to spherical systems in order to distinguish between cluster-forming systems and fluids which display reentrant melting. We use both DFT and Monte Carlo simulations to characterize the behavior of the system, and obtain semi-quantitative agreement between the two. We find that the number of clusters is determined by the ratio between the size s of the ultra-soft particles and the radius R of the sphere in such a way that each stable configuration spans a certain interval of s/R. Furthermore, we study the effect of topological frustration on the system due to the sphere curvature by comparing the properties of disclinations, i.e., clusters with fewer than six neighbors, and non-defective clusters. Disclinations are shown to be less stable, contain fewer particles, and be closer to their neighbors than other lattice points: these properties are explained on the basis of geometric and energetic considerations

Free light chain UV quantification compared with immunochemical measurement: How dimers and monomers may influence the results

Serum κ and λ free light chain (FLC) levels are important for the management of plasma cell disorders. Immunochemical measurements on automated platforms with different reagents occasionally return different results that make them not interchangeable. The reasons for this behaviour are not clear and it is not known which result is the most accurate. The aim of the study is to quantify naturally occurring FLCs with a reference method (UV absorbance) in a sample devoid of other sources of UV absorbance. This was possible on a particular urine sample containing only lambda FLC proteins, dialyzed to clear it from low molecular weight UV absorbing compounds. The sample was submitted to Fast Protein Liquid Chromatography separation with a size-exclusion column in order to separate the FLC monomers and dimers. FLCs were also measured with the Freelite and N Latex FLC methods and the results were compared. The results demonstrated that the amount of FLC calculated on the basis of UV absorbance was overestimated by both immunochemical methods, and that the amount measured by the two reagents was affected by the different proportions of dimers or monomers. The present findings may be useful for the comprehension of the immunochemical measurement of FLC

Light Bottom Squark Phenomenology

Agreement of theoretical calculations with the observed production rate of bottom quarks at hadron colliders is improved by the introduction of a contribution from pair-production of light gluinos, of mass 12 to 16 GeV, having two-body decays into bottom quarks and light bottom squarks with mass $\simeq 2$ to 5.5 GeV. Predictions are made for hadronic and radiative decays of the Upsilon states. In the limit of large $\tan\beta$, the dominant decay mode of the light scalar Higgs boson is into a pair of light bottom squarks that materialize as jets of hadrons.Comment: 3 pages, latex, no figures, uses espcrc2.sty style file. Paper to be published in the Proceedings of the 31st International Conference on High Energy Physics (ICHEP02), Amsterdam, July 24 - 31, 200

Optical issues for the diagnostic stations for the ELI-NP compton gamma source

A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. In order to measure the beam properties, the optical radiation detecting system must have the necessary accuracy and resolution. This paper deals with the studies of different optic configurations to achieve the magnification, resolution and accuracy in order to measure very small beam (below 30 μm) or to study the angular distribution of the OTR and therefore the energy of the beam. Several configurations of the optical detection line will be studied both with simulation tools (e.g. Zemax) and experimentally. The paper will deal also with the sensibility of optic system (in terms of depth of field, magnification and resolution) to systematic error

Emission of Two Hard Photons in Large-Angle Bhabha Scattering

A closed expression for the differential cross section of the large-angle Bhabha $e^+ e^-$ scattering which explicitly takes into account the leading and next-to-leading contributions due to the emission of two hard photons is presented. Both collinear and semi-collinear kinematical regions are considered. The results are illustrated by numerical calculations.Comment: 13 pages, LaTeX, 1 PostScript figure, submitted to Nucl. Phys.

Nanoscale patterning of STIM1 and Orai1 during store-operated Ca2+ entry

Stromal interacting molecule (STIM) and Orai proteins constitute the core machinery of store-operated calcium entry. We used transmission and freeze-fracture electron microscopy to visualize STIM1 and Orai1 at endoplasmic reticulum (ER)-plasma membrane (PM) junctions in HEK 293 cells. Compared with control cells, thin sections of STIM1-transfected cells possessed far more ER elements, which took the form of complex stackable cisternae and labyrinthine structures adjoining the PM at junctional couplings (JCs). JC formation required STIM1 expression but not store depletion, induced here by thapsigargin (TG). Extended molecules, indicative of STIM1, decorated the cytoplasmic surface of ER, bridged a 12-nm ER-PM gap, and showed clear rearrangement into small clusters following TG treatment. Freeze-fracture replicas of the PM of Orai1-transfected cells showed extensive domains packed with characteristic "particles"; TG treatment led to aggregation of these particles into sharply delimited "puncta" positioned upon raised membrane subdomains. The size and spacing of Orai1 channels were consistent with the Orai crystal structure, and stoichiometry was unchanged by store depletion, coexpression with STIM1, or an Orai1 mutation (L273D) affecting STIM1 association. Although the arrangement of Orai1 channels in puncta was substantially unstructured, a portion of channels were spaced at ?15 nm. Monte Carlo analysis supported a nonrandom distribution for a portion of channels spaced at ∼15 nm. These images offer dramatic, direct views of STIM1 aggregation and Orai1 clustering in store-depleted cells and provide evidence for the interaction of a single Orai1 channel with small clusters of STIM1 molecules

The Cultural Production of Health Inequalities: A Cross-Sectional, Multilevel Examination of 52 Countries

In a 2001 report, the U.S. National Institutes of Health called for more integration of the social sciences into health-related research, including research guided by theories and methods that take social and cultural systems into consideration. Based on a theoretical framework that integrates Hofstede\u27s cultural dimensions with sociological theory, the authors used multilevel modeling to explore the association of culture with structural inequality and health disparities. Their results support the idea that cultural dimensions and social structure, along with economic development, may account for much of the cross-national variation in the distribution of health inequalities. Sensitivity tests also suggest that an interaction between culture and social structure may confound the relationship between income inequality and health. It is necessary to identify important cultural and social structural characteristics before we can achieve an understanding of the complex, dynamic systems that affect health, and develop culturally sensitive interventions and policies. This study takes a step toward identifying some of the relevant cultural and structural influences. More research is needed to explore the pathways leading from the sociocultural environment to health inequalities