4,764 research outputs found

    Gauge-Higgs Unification In Spontaneously Created Fuzzy Extra Dimensions

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    We propose gauge-Higgs unification in fuzzy extra dimensions as a possible solution to the Higgs naturalness problem. In our approach, the fuzzy extra dimensions are created spontaneously as a vacuum solution of certain four-dimensional gauge theory. As an example, we construct a model which has a fuzzy torus as its vacuum. The Higgs field in our model is associated with the Wilson loop wrapped on the fuzzy torus. We show that the quadratic divergence in the mass of the Higgs field in the one-loop effective potential is absent. We then argue based on symmetries that the quantum corrections to the Higgs mass is suppressed including all loop contributions. We also consider a realization on the worldvolume theory of D3-branes probing C3/(ZN×ZN)C^3/(Z_N \times Z_N) orbifold with discrete torsion.Comment: 1+38 pages, 4 figures v2: refs adde

    Stochastic population growth in spatially heterogeneous environments

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    Classical ecological theory predicts that environmental stochasticity increases extinction risk by reducing the average per-capita growth rate of populations. To understand the interactive effects of environmental stochasticity, spatial heterogeneity, and dispersal on population growth, we study the following model for population abundances in nn patches: the conditional law of Xt+dtX_{t+dt} given Xt=xX_t=x is such that when dtdt is small the conditional mean of Xt+dtiXtiX_{t+dt}^i-X_t^i is approximately [xiμi+j(xjDjixiDij)]dt[x^i\mu_i+\sum_j(x^j D_{ji}-x^i D_{ij})]dt, where XtiX_t^i and μi\mu_i are the abundance and per capita growth rate in the ii-th patch respectivly, and DijD_{ij} is the dispersal rate from the ii-th to the jj-th patch, and the conditional covariance of Xt+dtiXtiX_{t+dt}^i-X_t^i and Xt+dtjXtjX_{t+dt}^j-X_t^j is approximately xixjσijdtx^i x^j \sigma_{ij}dt. We show for such a spatially extended population that if St=(Xt1+...+Xtn)S_t=(X_t^1+...+X_t^n) is the total population abundance, then Yt=Xt/StY_t=X_t/S_t, the vector of patch proportions, converges in law to a random vector YY_\infty as tt\to\infty, and the stochastic growth rate limtt1logSt\lim_{t\to\infty}t^{-1}\log S_t equals the space-time average per-capita growth rate \sum_i\mu_i\E[Y_\infty^i] experienced by the population minus half of the space-time average temporal variation \E[\sum_{i,j}\sigma_{ij}Y_\infty^i Y_\infty^j] experienced by the population. We derive analytic results for the law of YY_\infty, find which choice of the dispersal mechanism DD produces an optimal stochastic growth rate for a freely dispersing population, and investigate the effect on the stochastic growth rate of constraints on dispersal rates. Our results provide fundamental insights into "ideal free" movement in the face of uncertainty, the persistence of coupled sink populations, the evolution of dispersal rates, and the single large or several small (SLOSS) debate in conservation biology.Comment: 47 pages, 4 figure

    Circle of Willis variation in a complex stroke presentation: a case report

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    BACKGROUND: The impact of circle of Willis anatomical variation upon the presentation of stroke is probably underrecognised. CASE PRESENTATION: A 63-year-old right-handed woman developed a left hemiparesis and right leg weakness sequentially following a road traffic accident (RTA). Despite initial concern about the possibility of cervical spinal cord injury, the final diagnosis was bilateral artery-to-artery embolic cerebral infarction with dominant right internal carotid artery. CONCLUSION: The case illustrates the complex presentation of stroke as a pseudo-cervical cord lesion and the impact of circle of Willis anatomical variation upon the expression of large vessel cerebrovascular disease

    Stem cell differentiation increases membrane-actin adhesion regulating cell blebability, migration and mechanics

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    This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder in order to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/K. S. is funded by an EPSRC PhD studentship. S.T. is funded by an EU Marie Curie Intra European Fellowship (GENOMICDIFF)

    WPŁYW WYCIĄGÓW Z ROŚLIN BODZISZKOWATYCH NA BIELINKA KAPUSTNIKA

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    The conducted studies comprised the analyses of activity of extracts derived from selected plants of the Geranium family on some processes of large white butterfly (Pieris brassicae) development (oviposition, survival of eggs and caterpillar feeding). The results proved that all tested extracts showed activity against large white butterfly. Geranium pratense L. and Geranium senquineum L. showed better activity than other Geranium plants. Water extracts from these species protected cabbage plants against laying eggs, while applied on eggs caused their mortality. Alcohol and water extracts from G. pratense L. and water extracts from G. senquineum L. increased an amount of food put on mass gain of caterpillars.Analizowano oddziaływanie ekstraktów uzyskanych z wybranych roślin z rodziny Bodziszkowate na: rozwój bielinka kapustnika (przebieg składania jaj, przeżywalność jaj oraz na żerowanie gąsienic). Stwierdzono, że wszystkie testowane wyciągi, wykazywały aktywne działanie w stosunku do bielinka kapustnika. Szczególnie wyróżniały się bodziszek łąkowy i bodziszek czerwony. Wodne wyciągi z tych roślin chroniły rośliny kapusty przed składaniem na nie jaj przez samice, a zastosowane na jaja, powodowały ich zamieranie. Alkoholowy i wodny wyciąg z bodziszka łąkowego oraz wyciąg wodny z bodziszka czerwonego wpływały na zwiększenie ilości pokarmu zużywanego na przyrost masy ciała gąsienic

    Systemic effects of epidural methylprednisolone injection on glucose tolerance in diabetic patients

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    ABSTRACT: BACKGROUND: Several studies have shown that in diabetic patients, the glycemic profile was disturbed after intra-articular injection of corticosteroids. Little is known about the impact of epidural injection in such patients. The goal of this study was double, at first comparing the glycaemic profile in diabetic patients after a unique injection of 80 mg of acetate methylprednisolone either intra-articular or epidural and secondly to compare the amount of systemic diffusion of the drug after both procedures. METHODS: Seventeen patients were included. Glycemic changes were compared in 9 diabetic patients following intra-articular (4 patients) and epidural injections (5 patients). Epidural injections were performed using the sacral route under fluoroscopic control in patients with lumbar spinal stenosis. Diabetes control had to stable for more than 10 days and the renal function to be preserved. Blood glucose was monitored using a validated continuous measuring device (GMS, Medtronic) the day before and for two days following the injection. Results were expressed in the form of daily glycemic profiles and as by mean, peak and minimal values +/ SD. The urinary excretion of methylprednisolone after the 2 routes of injection was analyzed in 8 patients (4 in each group). Urine samples were cropped one hour before the injections, then 4 times during the first day and 3 times a week for 2 weeks. The measurements included the free and conjugated fraction RESULTS: The glycaemic profile remains unchanged with no significant changes in the group of the 5 diabetic patients receiving epidural injections. On the other end, the average peak and mean values were enhanced up to 3 mmol/l above baseline two days after the infiltration in the groups of the 4 diabetic patients infiltrated intra-articular. The mean urinary excretion of the steroid was about ten times higher in the intra-articular versus epidural group: 7000 ng/ml versus 700 ng/ml. Looking at each individual there were marked differences especially after intra-articular injections. CONCLUSION: This is the first study to show that a single epidural steroid injection of 80 mg depot methylprednisolone had no effect on the glycemic control in diabetic patients. The absence of glycemic control changes correlated well with the very low urinary excretion of the drug after epidural injection. Trial registration NCT01420497

    Diagnostic delay for giant cell arteritis – a systematic review and meta-analysis

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    Background Giant cell arteritis (GCA), if untreated, can lead to blindness and stroke. The study’s objectives were to (1) determine a new evidence-based benchmark of the extent of diagnostic delay for GCA and (2) examine the role of GCA-specific characteristics on diagnostic delay. Methods Medical literature databases were searched from inception to November 2015. Articles were included if reporting a time-period of diagnostic delay between onset of GCA symptoms and diagnosis. Two reviewers assessed the quality of the final articles and extracted data from these. Random-effects meta-analysis was used to pool the mean time-period (95% confidence interval (CI)) between GCA symptom onset and diagnosis, and the delay observed for GCA-specific characteristics. Heterogeneity was assessed by I 2 and by 95% prediction interval (PI). Results Of 4128 articles initially identified, 16 provided data for meta-analysis. Mean diagnostic delay was 9.0 weeks (95% CI, 6.5 to 11.4) between symptom onset and GCA diagnosis (I 2 = 96.0%; P < 0.001; 95% PI, 0 to 19.2 weeks). Patients with a cranial presentation of GCA received a diagnosis after 7.7 (95% CI, 2.7 to 12.8) weeks (I 2 = 98.4%; P < 0.001; 95% PI, 0 to 27.6 weeks) and those with non-cranial GCA after 17.6 (95% CI, 9.7 to 25.5) weeks (I 2 = 96.6%; P < 0.001; 95% PI, 0 to 46.1 weeks). Conclusions The mean delay from symptom onset to GCA diagnosis was 9 weeks, or longer when cranial symptoms were absent. Our research provides an evidence-based benchmark for diagnostic delay of GCA and supports the need for improved public awareness and fast-track diagnostic pathways

    Recapitulation of Human Retinal Development from Human Pluripotent Stem Cells Generates Transplantable Populations of Cone Photoreceptors

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    Transplantation of rod photoreceptors, derived either from neonatal retinae or pluripotent stem cells (PSCs), can restore rod-mediated visual function in murine models of inherited blindness. However, humans depend more upon cone photoreceptors that are required for daylight, color, and high-acuity vision. Indeed, macular retinopathies involving loss of cones are leading causes of blindness. An essential step for developing stem cell-based therapies for maculopathies is the ability to generate transplantable human cones from renewable sources. Here, we report a modified 2D/3D protocol for generating hPSC-derived neural retinal vesicles with well-formed ONL-like structures containing cones and rods bearing inner segments and connecting cilia, nascent outer segments, and presynaptic structures. This differentiation system recapitulates human photoreceptor development, allowing the isolation and transplantation of a pure population of stage-matched cones. Purified human long/medium cones survive and become incorporated within the adult mouse retina, supporting the potential of photoreceptor transplantation for treating retinal degeneration
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