Ambivalence of the anisotropy of the vortex lattice in an anisotropic type-II superconductor

We present a geometry-based discussion of possible vortex configurations in the mixed state of anisotropic type-II superconductors. It is shown that, if energy considerations assign six nearest neighbors to each vortex, two distinct modifications of the vortex lattice are possible. It is expected that certain conditions lead to a first order phase transition from one modification of the vortex lattice to the other upon varying the external magnetic field.Comment: 3 pages, 2 figure

Intra- and interspecies interactions between prion proteins and effects of mutations and polymorphisms

Recently, crystallization of the prion protein in a dimeric form was reported. Here we show that native soluble homogenous FLAG-tagged prion proteins from hamster, man and cattle expressed in the baculovirus system are predominantly dimeric. The PrP/PrP interaction was confirmed in Semliki Forest virus-RNA transfected BHK cells co-expressing FLAG- and oligohistidine-tagged human PrP. The yeast two-hybrid system identified the octarepeat region and the C-terminal structured domain (aa90-aa230) of PrP as PrP/PrP interaction domains. Additional octarepeats identified in patients suffering from fCJD reduced (wtPrP versus PrP+90R) and completely abolished (PrP+90R versus PrP+90R) the PrP/PrP interaction in the yeast two-hybrid system. In contrast, the Met/Val polymorphism (aa129), the GSS mutation Pro102Leu and the FFI mutation Asp178Asn did not affect PrP/PrP interactions. Proof of interactions between human or sheep and bovine PrP, and sheep and human PrP, as well as lack of interactions between human or bovine PrP and hamster PrP suggest that interspecies PrP interaction studies in the yeast two-hybrid system may serve as a rapid pre-assay to investigate species barriers in prion diseases

Standing Without Gravity: the Use of Lower Body Negative Pressure for Research and Reconditioning in Spaceflight

Weightlessness during spaceflight causes cephalad redistribution of intravascular and extravascular fluid, provoking cardiovascular and autonomic nervous system adaptations. The resulting functional state is appropriate for weightlessness but can result in orthostatic hypotension and intolerance during and after return to a persistent acceleration or gravitational environment. Lower body negative pressure (LBNP) applies subambient air pressure to the legs and lower abdomen inside a volume sealed at the waist, and decompression by 4050 mmHg reverses the spaceflightinduced cephalad shift. LBNP has been used both to test the state of cardiovascular system during spaceflight and as a countermeasure by all spacefaring nations. Two configurations have thus far been used in spaceflight since the first LBNP flew on the first Soviet Salyut station in 1971. The Soviet and Russian configuration, used in four Salyut stations, the Mir space station and the Russian segment of the International Space Station, has no saddle to support the body so during decompression the feet press against the bottom of the collapsible chamber which shortens and applies force against the feet proportional to the decompression level. Thus, activation of the skeletal musculature partially counteracts vascular and venous pooling in the enclosed body segments, stimulating the orthostatic compensatory mechanisms as they would be standing on Earth. In the American configuration, used aboard Skylab and the Space Shuttle, a saddle supported the astronaut so the feet did not contact the bottom of the chamber, and vascular engorgement was not countered by muscular contraction. This minimized skeletal muscle involvement, unmasked vascular compensatory mechanisms for research purposes, and allowed measurements of changes in leg volume and muscle sympathetic nerve activity. Both variants have demonstrated research and therapeutic value in appropriately designed protocols. LBNP continues to be used for research and countermeasures on ISS, and future versions may explore the value of exercise during LBNP as an integrated countermeasure. This paperwill review the history and development of LBNP for spaceflight research and therapeutic purposes

Excitation spectrum of vortex lattices in rotating Bose-Einstein condensates

Using the coarse grain averaged hydrodynamic approach, we calculate the excitation spectrum of vortex lattices sustained in rotating Bose-Einstein condensates. The spectrum gives the frequencies of the common-mode longitudinal waves in the hydrodynamic regime, including those of the higher-order compressional modes. Reasonable agreement with the measurements taken in a recent JILA experiment is found, suggesting that one of the longitudinal modes reported in the experiment is likely to be the $n=2$, $m=0$ mode.Comment: 2 figures. Submitted to Physical Review A. v2 contains more references. No change in the main resul

Inhomogeneous chiral symmetry breaking in noncommutative four fermion interactions

The generalization of the Gross-Neveu model for noncommutative 3+1 space-time has been analyzed. We find indications that the chiral symmetry breaking occurs for an inhomogeneous background as in the LOFF phase in condensed matter.Comment: 17 pages, 2 figures, published version, minor correction

Strong, weak and flavor scalar triplets for the CDF Wjj anomaly

A model describing the 4.1\sigma\ Wjj anomaly observed by the CDF experiment at the Tevatron collider is introduced. It features new scalar particles which are charged both under the SU(3)_C and the SU(2)_L gauge groups and which couple to pairs of quarks. We introduce several identical replicas of the scalar multiplets in order to leave an unbroken U(3)_Q x U(3)_U x U(3)_D flavor symmetry to satisfy the constraints coming from flavor physics. We discuss the LHC reach on the new scalar resonances both in the resonant production channel (with the Wjj final state) and in the QCD pair production channel (with the 4j final state).Comment: 17 pages, 6 figures and 4 table

Effects of unidirectional flow shear stresses on the formation, fractal microstructure and rigidity of incipient whole blood clots and fibrin gels

Incipient clot formation in whole blood and fibrin gels was studied by the rheometric techniques of controlled stress parallel superposition (CSPS) and small amplitude oscillatory shear (SAOS). The effects of unidirectional shear stress on incipient clot microstructure, formation kinetics and elasticity are reported in terms of the fractal dimension (df ) of the fibrin network, the gel network formation time (TGP ) and the shear elastic modulus, respectively. The results of this first haemorheological application of CSPS reveal the marked sensitivity of incipient clot microstructure to physiologically relevant levels of shear stress, these being an order of magnitude lower than have previously been studied by SAOS. CSPS tests revealed that exposure of forming clots to increasing levels of shear stress produces a corresponding elevation in df , consistent with the formation of tighter, more compact clot microstructures under unidirectional flow. A corresponding increase in shear elasticity was recorded. The scaling relationship established between shear elasticity and df for fibrin clots and whole blood confirms the fibrin network as the dominant microstructural component of the incipient clot in terms of its response to imposed stress. Supplementary studies of fibrin clot formation by rheometry and microscopy revealed the substantial additional network mass required to increase df and provide evidence to support the hypothesis that microstructural changes in blood clotted under unidirectional shear may be attributed to flow enhanced thrombin generation and activation. CSPS also identified a threshold value of unidirectional shear stress above which no incipient clot formation could be detected. CSPS was shown to be a valuable haemorheological tool for the study of the effects of physiological and pathological levels of shear on clot properties

A New Neutrino Cross Section Database

We describe a new web based data resource being developed to provide access to accurate and validated cross sections of low energy neutrino and antineutrino interactions. The proposed content of this database are outlined which cover total and differential cross from inclusive, quasi-elastic and exclusive pion production processes from charged and neutral current interactions. Efforts to obtain these data, which come mainly from old bubble chamber experiments, are described as well as the implementation of an embryonic web site to make the resource generally accessible.Comment: 6 pages, 3 figures, To appear in the proceedings of the 3rd International Workshop on Neutrino Nucleus Interactions in the few GeV region (NuInt04), Gran Sasso, Assergi, Italy, 17-21 Mar 200

Socket interface pressure and amputee reported outcomes for comfortable and uncomfortable conditions of patellar tendon bearing socket: a pilot study

The objectives of the current study were to compare intra-socket pressure differences between comfortable and uncomfortable socket conditions, and the usefulness of subject perception of satisfaction, activity limitations, and socket comfort in distinguishing between these two socket conditions. Five unilateral trans-tibial amputees took part in the study. They answered the Socket Comfort Score (SCS) and Trinity Amputation and Prosthetic Experience Scale (TAPES) questionnaires before the interface pressure (in standing and walking) was measured for the uncomfortable socket condition at five regions of the residual limb. Participants were then provided with a comfortable socket and wore it for two weeks. Participants who were satisfied with the socket fit after two weeks repeated the SCS and TAPES questionnaires and interface pressure measurements. The differences between the test results of the two conditions were not statistically significant, except for the interface pressure at the popliteal region during the early stance phase, TAPES socket fit subscale, and the SCS. Due to large variability of the data and the lack of statistical significance, no firm conclusion can be made on the possible relationship between the interface pressure values and the patient-reported outcomes of the two socket conditions. A larger sample size and longer acclimation period are required to locate significant differences.N/