Equivalent variational approaches to biaxial liquid crystal dynamics

Within the framework of liquid crystal flows, the Qian & Sheng (QS) model for Q-tensor dynamics is compared to the Volovik & Kats (VK) theory of biaxial nematics by using Hamilton's variational principle. Under the assumption of rotational dynamics for the Q-tensor, the variational principles underling the two theories are equivalent and the conservative VK theory emerges as a specialization of the QS model. Also, after presenting a micropolar variant of the VK model, Rayleigh dissipation is included in the treatment. Finally, the treatment is extended to account for nontrivial eigenvalue dynamics in the VK model and this is done by considering the effect of scaling factors in the evolution of the Q-tensor.Comment: 8 pages. Third versio

FSI Rescattering in B±B^\pm Decays via States with η,η′,ω\eta, \eta', \omega and ϕ\phi

New results going beyond those obtained from isospin and flavor symmetry and subject to clear experimental tests are obtained for effects of FSI in $B^\pm$ decays to charmless strange final states containing neutral flavor-mixed mesons like $\omega$, $\phi$, $\eta$ and $\eta'$. The most general strong-interaction diagrams containing arbitrary numbers of quarks and gluons are included with the assumptions that any $q \bar q$ pair created by gluons must be a flavor singlet, and that there are no hairpin diagrams in which a final meson contains a $q \bar q$ pair from the same gluon vertex. The smallness of $K^- \eta$ suggests that it might have a large CP violation. A sum rule is derived to test whether the large $K^- \eta'$ requires the addition of an additional glueball or charm admixture. Further analysis from $D_s$ decay systematics supports this picture of FSI and raises questions about charm admixture in the $\eta'$

Spatial attention can be biased towards an expected dimension

A commonly held view in both exogenous and endogenous orienting is that spatial attention is associated with enhanced processing of all stimuli at the attended location. However, we often search for a specific target at a particular location, so an observer should be able to jointly specify the target identity and expected location. Whether attention can bias dimension-specific processes at a particular location is not yet clear. We used a dual task to examine the effects of endogenous spatial cues on the accuracy of perceptual judgments of different dimensions. Participants responded to a motion target and a colour target, presented at the same or different locations. We manipulated a central cue to predict the location of the motion or colour target. While overall performance in the two tasks was comparable, cueing effects were larger for the target whose location was predicted by the cue, implying that when attending a particular location, processing of the likely dimension was preferentially enhanced. Additionally, an asymmetry between the motion and colour tasks was seen; motion was modulated by attention, and colour was not. We conclude that attention has some ability to select a dimension at a particular location, indicating integration of spatial and feature-based attention. </jats:p

Ontogenetic scaling patterns and functional anatomy of the pelvic limb musculature in emus (Dromaius novaehollandiae)

Emus (Dromaius novaehollandiae) are exclusively terrestrial, bipedal and cursorial ratites with some similar biomechanical characteristics to humans. Their growth rates are impressive, as their body mass increases eighty-fold from hatching to adulthood whilst maintaining the same mode of locomotion throughout life. These ontogenetic characteristics stimulate biomechanical questions about the strategies that allow emus to cope with their rapid growth and locomotion, which can be partly addressed via scaling (allometric) analysis of morphology. In this study we have collected pelvic limb anatomical data (muscle architecture, tendon length, tendon mass and bone lengths) and calculated muscle physiological cross sectional area (PCSA) and average tendon cross sectional area from emus across three ontogenetic stages (n = 17, body masses from 3.6 to 42 kg). The data were analysed by reduced major axis regression to determine how these biomechanically relevant aspects of morphology scaled with body mass. Muscle mass and PCSA showed a marked trend towards positive allometry (26 and 27 out of 34 muscles respectively) and fascicle length showed a more mixed scaling pattern. The long tendons of the main digital flexors scaled with positive allometry for all characteristics whilst other tendons demonstrated a less clear scaling pattern. Finally, the two longer bones of the limb (tibiotarsus and tarsometatarsus) also exhibited positive allometry for length, and two others (femur and first phalanx of digit III) had trends towards isometry. These results indicate that emus experience a relative increase in their muscle force-generating capacities, as well as potentially increasing the force-sustaining capacities of their tendons, as they grow. Furthermore, we have clarified anatomical descriptions and provided illustrations of the pelvic limb muscle–tendon units in emus

Perturbative Prediction for Parton Fragmentation into Heavy Hadron

By expanding functions of parton fragmentation into a heavy hadron in the inverse of the heavy quark mass $m_Q$ we attempt to factorize them into perturbative- and nonperturbative parts. In our approach the nonperturbative parts can be defined as matrix elements in heavy quark effective theory, the shape of the functions is predicted by perturbative QCD. In this work we neglect effect at order of $m_Q^{-2}$ and calculate the perturbative parts at one-loop level for heavy quark- and gluon fragmentation. We compare our results from leading log approximation with experimental results from $e^+e^-$ colliders and find a deviation below or at 10% level. Adding effect of higher order in $\alpha_s$ it can be expected to reduce the deviation. The size of matrix elements appearing at the order we consider for several types of heavy hadrons is determined.Comment: 21 pages + 3 pages figures, plain te

Delta s density in a proton and unpolarized lepton - polarized proton scatterings

It is shown that the parity--violating deep--inelastic scatterings of unpolarized charged leptons on polarized protons, $\ell^{\mp} + \vec P\to \stackrel{\scriptscriptstyle(-)}{\nu_{\ell}} + X$, could provide a sensitive test for the behavior and magnitude of the polarized strange--quark density in a proton. Below charm threshold these processes are also helpful to uniquely determine the magnitude of individual polarized parton distributions.Comment: LaTeX file, 12 pages+4 fiigures not included (available upon request

Searching for sub-stellar companion into the LkCa15 proto-planetary disk

Recent sub-millimetric observations at the Plateau de Bure interferometer evidenced a cavity at ~ 46 AU in radius into the proto-planetary disk around the T Tauri star LkCa15 (V1079 Tau), located in the Taurus molecular cloud. Additional Spitzer observations have corroborated this result possibly explained by the presence of a massive (>= 5 MJup) planetary mass, a brown dwarf or a low mass star companion at about 30 AU from the star. We used the most recent developments of high angular resolution and high contrast imaging to search directly for the existence of this putative companion, and to bring new constraints on its physical and orbital properties. The NACO adaptive optics instrument at VLT was used to observe LkCa15 using a four quadrant phase mask coronagraph to access small angular separations at relatively high contrast. A reference star at the same parallactic angle was carefully observed to optimize the quasi-static speckles subtraction (limiting our sensitivity at less than 1.0). Although we do not report any positive detection of a faint companion that would be responsible for the observed gap in LkCa15's disk (25-30 AU), our detection limits start constraining its probable mass, semi-major axis and eccentricity. Using evolutionary model predictions, Monte Carlo simulations exclude the presence of low eccentric companions with masses M >= 6 M Jup and orbiting at a >= 100 AU with significant level of confidence. For closer orbits, brown dwarf companions can be rejected with a detection probability of 90% down to 80 AU (at 80% down to 60 AU). Our detection limits do not access the star environment close enough to fully exclude the presence of a brown dwarf or a massive planet within the disk inner activity (i.e at less than 30 AU). Only, further and higher contrast observations should unveil the existence of this putative companion inside the LkCa15 disk.Comment: 6 pages, 4 figures, accepted for publication in A&

Comparison of Protocols to Reduce Diabetic Ketoacidosis in Patients With Type 1 Diabetes Prescribed a Sodium–Glucose Cotransporter 2 Inhibitor

OBJECTIVE Sodium–glucose cotransporter 2 (SGLT2) inhibitors are approved for type 1 diabetes in Europe and Japan, with off-label use in type 1 diabetes in the United States. Although there were no consistent approaches to risk mitigation in clinical trials of these agents, protocols have been developed to try to reduce the risk of diabetic ketoacidosis (DKA). However, a validated risk mitigation strategy does not exist. We reviewed available DKA risk mitigation protocols to better understand the various strategies currently in use. METHODS We conducted a search of the published medical literature and other medical information sources, including conference presentations, for protocols. We then categorized the information provided into guidance on patient se-lection, initiation of SGLT2 inhibitors, ketone monitoring, necessary patient action in the event of ketosis or DKA, and inpatient treatment of ketosis or DKA. RESULTS Patient selection is generally similar among the protocols, although some require a minimum BMI and insulin dose. All protocols advocate routine measurement of ketones, although some insist on blood ketone tests. Although action steps for ketosis varies, all protocols advocate rapid patient intervention. The importance of evaluating ketones and acid-base balance even in the absence of hyperglycemia is emphasized by all protocols, as is the need to continue administering insulin until ketosis has resolved. CONCLUSION DKA risk mitigation must be pursued systematically in individuals with type 1 diabetes, although the best strategy remains to be determined. Given the ongoing need for adjunctive therapies in type 1 diabetes and current use of SGLT2 inhibitors for this purpose, additional education and research are crucial, especially in the hospital environment, where DKA may not be diagnosed promptly and treated appropriately

Measuring tiny mass accretion rates onto young brown dwarfs

We present low-resolution Keck I/LRIS spectra spanning from 3200-9000 A of nine young brown dwarfs and three low-mass stars in the TW Hya Association and in Upper Sco. The optical spectral types of the brown dwarfs range from M5.5-M8.75, though two have near-IR spectral types of early L-dwarfs. We report new accretion rates derived from excess Balmer continuum emission for the low-mass stars TW Hya and Hen 3-600A and the brown dwarfs 2MASS J12073347-3932540, UScoCTIO 128, SSSPM J1102-3431, UScoJ160606.29-233513.3, DENIS-P J160603.9-205644, and Oph J162225-240515B, and upper limits on accretion for the low-mass star Hen 3-600B and the brown dwarfs UScoCTIO 112, Oph J162225-240515A, and USco J160723.82-221102.0. For the six brown dwarfs in our sample that are faintest at short wavelengths, the accretion luminosity or upper limit is measurable only when the image is binned over large wavelength intervals. This method extends our sensivity to accretion rate down to ~1e-13 solar masses/year for brown dwarfs. Since the ability to measure an accretion rate from excess Balmer continuum emission depends on the contrast between excess continuum emission and the underlying photosphere, for objects with earlier spectral types the upper limit on accretion rate is much higher. Absolute uncertainties in our accretion rate measurements of ~3-5 include uncertainty in accretion models, brown dwarf masses, and distance. The accretion rate of 2e-12 solar masses/year onto 2MASS J12073347-3932540 is within 15% of two previous measurements, despite large changes in the H-alpha flux.Comment: Accepted by ApJ. 23 pages, 5 figures, 3 table