A Low-Dimensional Model of Coordinated Eye and Head Movements

Eye and head movement data, were recorded under head fixed and head-free conditions, and compared with theoretical results obtained using a nonlinear model of eye-head coordination. The model explains slow, or pursuit movement correlated closely to target movement, and saccades, or quick phases of eye movement. Eye movement under head-fixed conditions was modeled by an externally forced Duffing equation, whilst properties of head movement are described by a second externally forced Duffing equation with lower eigen frequency. In the more natural, head-free conditions where both eye and head movements are used synergetically to pursue a visual target, the vestibulocular reflex (VOR) is represented by coefficients defining the mutual coupling between these two oscillatory systems. In the present model, the oscillator that models eye movement has an inhibitory influence on head movement; head to eye coupling coefficients are included to model the influence of the VOR mechanism. Individual eye and head movement patterns in different subjects can be adequately modeled by altering the coupling coefficients. In order to adequatcly simulate those changes introduced by microgravity conditions, the coefficients defining eye-head coordination (mutual coupling) must be changed. It may be hypothesized tlmt such changes in the neurovestibular system could introduce the instability in eye-head coordination, which is known to lead to space sickness.Whitehall Foundation (S93-24

Counterexample Guided Abstraction Refinement Algorithm for Propositional Circumscription

Circumscription is a representative example of a nonmonotonic reasoning inference technique. Circumscription has often been studied for first order theories, but its propositional version has also been the subject of extensive research, having been shown equivalent to extended closed world assumption (ECWA). Moreover, entailment in propositional circumscription is a well-known example of a decision problem in the second level of the polynomial hierarchy. This paper proposes a new Boolean Satisfiability (SAT)-based algorithm for entailment in propositional circumscription that explores the relationship of propositional circumscription to minimal models. The new algorithm is inspired by ideas commonly used in SAT-based model checking, namely counterexample guided abstraction refinement. In addition, the new algorithm is refined to compute the theory closure for generalized close world assumption (GCWA). Experimental results show that the new algorithm can solve problem instances that other solutions are unable to solve

Exact solutions of noncommutative vacuum Einstein field equations and plane-fronted gravitational waves

We construct a class of exact solutions of the noncommutative vacuum Einstein field equations, which are noncommutative analogues of the plane-fronted gravitational waves in classical gravity.Comment: 10 pages, comments adde

Depletion of Trp53 and Cdkn2a does not promote self-renewal in the mammary gland but amplifies proliferation induced by TNF-α

Dermatology-oncolog

76 T dwarfs from the UKIDSS LAS : benchmarks, kinematics and an updated space density

We report the discovery of 76 new T dwarfs from the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). Near-infrared broad- and narrow-band photometry and spectroscopy are presented for the new objects, along with Wide-field Infrared Survey Explorer (WISE) and warm-Spitzer photometry. Proper motions for 128 UKIDSS T dwarfs are presented from a new two epoch LAS proper motion catalogue. We use these motions to identify two new benchmark systems: LHS 6176AB, a T8p+M4 pair and HD 118865AB, a T5.5+F8 pair. Using age constraints from the primaries and evolutionary models to constrain the radii, we have estimated their physical properties from their bolometric luminosity. We compare the colours and properties of known benchmark T dwarfs to the latest model atmospheres and draw two principal conclusions. First, it appears that the H - [4.5] and J - W2 colours are more sensitive to metallicity than has previously been recognized, such that differences in metallicity may dominate over differences in T-eff when considering relative properties of cool objects using these colours. Secondly, the previously noted apparent dominance of young objects in the late-T dwarf sample is no longer apparent when using the new model grids and the expanded sample of late-T dwarfs and benchmarks. This is supported by the apparently similar distribution of late-T dwarfs and earlier type T dwarfs on reduced proper motion diagrams that we present. Finally, we present updated space densities for the late-T dwarfs, and compare our values to simulation predictions and those from WISE.Peer reviewe

Large-scale magnetic fields from inflation in dilaton electromagnetism

The generation of large-scale magnetic fields is studied in dilaton electromagnetism in inflationary cosmology, taking into account the dilaton's evolution throughout inflation and reheating until it is stabilized with possible entropy production. It is shown that large-scale magnetic fields with observationally interesting strength at the present time could be generated if the conformal invariance of the Maxwell theory is broken through the coupling between the dilaton and electromagnetic fields in such a way that the resultant quantum fluctuations in the magnetic field has a nearly scale-invariant spectrum. If this condition is met, the amplitude of the generated magnetic field could be sufficiently large even in the case huge amount of entropy is produced with the dilution factor $\sim 10^{24}$ as the dilaton decays.Comment: 28 pages, 5 figures, the version accepted for publication in Phys. Rev. D; some references are adde

Variability in the efficacy of a standardized antenatal steroid treatment is not due to maternal or fetal plasma drug levels. Evidence from a sheep model of pregnancy.

Background Antenatal steroids (ANS) are standard of care for women judged to be at imminent risk of preterm delivery. Worldwide, there is significant variation in ANS dosing strategy, selection for treatment criteria, and agent choice. This, combined with very limited optimization of ANS use per se means that treatment efficacy is highly variable and the rate of respiratory distress syndrome is decreased perhaps as little as 40%. In some cases, ANS use is associated with limited benefit and potential harm. Objective We hypothesized that individual differences in maternal and fetal steroid exposure would contribute to observed variability in ANS treatment efficacy. Using a chronically catheterized sheep model of pregnancy, we aimed to explore the relationship between materno-fetal steroid exposure and ANS treatment efficacy as determined by functional lung maturation in preterm lambs undergoing ventilation. Methods Ewes carrying a single fetus had surgery to catheterize a fetal and maternal jugular vein at 119 days’ gestation. Animals recovered for 24h before being randomized to either: i) a single maternal intramuscular injection (IM) of 2ml saline (Negative Control Group, n=10); or ii) a single maternal IM of 0.25mg/kg betamethasone phosphate + acetate (ANS Group, n=20). Serial maternal and fetal plasma samples were collected from each animal over 48h before fetuses were delivered and ventilated for 30 minutes. Total and free plasma betamethasone concentration was measured by mass spectrometry. Fetal lung tissue was collected for analysis using quantitative polymerase chain reaction. Results One animal of the Control Group and one animal from the ANS Group had did not complete their treatment protocol and were removed from analyses. Animals in the ANS Group were divided into a Responder (n=12/19) Sub-Group and a Non-Responder Sub-Group (n=7/19) using a cut-off of a PaCO2 at 30 minutes ventilation within 2SD of the mean value from saline-treated Negative Control Group animals. While ANS improved fetal lung maturation in the undivided ANS group, and in the Responder Sub-Group both physiologically (blood gas and ventilation related data) and biochemically (mRNA expression related to fetal lung maturation), these values were not improved relative to saline-treated Control Group animals in the ANS Non-Responder Sub-Group. Interestingly, no differences in betamethasone distribution, clearance, or protein binding were identified between the ANS Responder and Non-Responder Sub-Groups. Conclusion This study correlated individual materno-fetal steroid exposures with preterm lung maturation as determined by pulmonary ventilation. Herein, approximately 40% of preterm lambs exposed to antenatal steroids had lung maturation not significantly different to saline-treated Control Group animals. These non-responsive animals received maternal and fetal betamethasone exposures identical to animals that had a significant improvement in functional lung maturation. These data suggest that the efficacy of ANS therapy is not solely determined by materno-fetal drug levels, and that individual fetal or maternal factors may play a role in determining treatment outcomes in response to glucocorticoid-driven signaling

A complete 3D numerical study of the effects of pseudoscalar-photon mixing on quasar polarizations

We present the results of three-dimensional simulations of quasar polarizations in the presence of pseudoscalar-photon mixing in the intergalactic medium. The intergalactic magnetic field is assumed to be uncorrelated in wave vector space but correlated in real space. Such a field may be obtained if its origin is primordial. Furthermore we assume that the quasars, located at cosmological distances, have negligible initial polarization. In the presence of pseudoscalar-photon mixing we show, through a direct comparison with observations, that this may explain the observed large scale alignments in quasar polarizations within the framework of big bang cosmology. We find that the simulation results give a reasonably good fit to the observed data.Comment: 15 pages, 8 figures, significant changes, to appear in EPJ

Discarded livers tested by normothermic machine perfusion in the VITTAL trial:Secondary end points and 5-year outcomes

Normothermic machine perfusion (NMP) enables pretransplant assessment of high-risk donor livers. The VITTAL trial demonstrated that 71% of the currently discarded organs could be transplanted with 100% 90-day patient and graft survivals. Here, we report secondary end points and 5-year outcomes of this prospective, open-label, phase 2 adaptive single-arm study. The patient and graft survivals at 60 months were 82% and 72%, respectively. Four patients lost their graft due to nonanastomotic biliary strictures, one caused by hepatic artery thrombosis in a liver donated following brain death, and 3 in elderly livers donated after circulatory death (DCD), which all clinically manifested within 6 months after transplantation. There were no late graft losses for other reasons. All the 4 patients who died during the study follow-up had functioning grafts. Nonanastomotic biliary strictures developed in donated after circulatory death livers that failed to produce bile with pH &gt;7.65 and bicarbonate levels &gt;25 mmol/L. Histological assessment in these livers revealed high bile duct injury scores characterized by arterial medial necrosis. The quality of life at 6 months significantly improved in all but 4 patients suffering from nonanastomotic biliary strictures. This first report of long-term outcomes of high-risk livers assessed by normothermic machine perfusion demonstrated excellent 5-year survival without adverse effects in all organs functioning beyond 1 year (ClinicalTrials.gov number NCT02740608).</p