529 research outputs found

    Charge Lattices and Consistency of 6D Supergravity

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    We extend the known consistency conditions on the low-energy theory of six-dimensional N = 1 supergravity. We review some facts about the theory of two-form gauge fields and conclude that the charge lattice Gamma for such a theory has to be self-dual. The Green-Schwarz anomaly cancellation conditions in the supergravity theory determine a sublattice of Gamma. The condition that this sublattice can be extended to a self-dual lattice Gamma leads to a strong constraint on theories that otherwise appear to be self-consistent.Comment: 15 pages. v2: minor changes; references, additional example added; v3: minor corrections and clarifications added, JHEP versio

    Comments on Supercurrent Multiplets, Supersymmetric Field Theories and Supergravity

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    We analyze various supersymmetry multiplets containing the supercurrent and the energy-momentum tensor. The most widely known such multiplet, the Ferrara-Zumino (FZ) multiplet, is not always well-defined. This can happen once Fayet-Iliopoulos (FI) terms are present or when the Kahler form of the target space is not exact. We present a new multiplet S which always exists. This understanding of the supersymmetry current allows us to obtain new results about the possible IR behavior of supersymmetric theories. Next, we discuss the coupling of rigid supersymmetric theories to supergravity. When the theory has an FZ-multiplet or it has a global R-symmetry the standard formalism can be used. But when this is not the case such simple gauging is impossible. Then, we must gauge the current S. The resulting theory has, in addition to the graviton and the gravitino, another massless chiral superfield Phi which is essential for the consistency of the theory. Some of the moduli of various string models play the role of Phi. Our general considerations, which are based on the consistency of supergravity, show that such moduli cannot be easily lifted thus leading to constraints on gravity/string models.Comment: 27 pages. v2: references added and minor changes. v3: minor changes. v4: minor clarification

    Rigid Supersymmetric Theories in Curved Superspace

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    We present a uniform treatment of rigid supersymmetric field theories in a curved spacetime M\mathcal{M}, focusing on four-dimensional theories with four supercharges. Our discussion is significantly simpler than earlier treatments, because we use classical background values of the auxiliary fields in the supergravity multiplet. We demonstrate our procedure using several examples. For M=AdS4\mathcal{M}=AdS_4 we reproduce the known results in the literature. A supersymmetric Lagrangian for M=S4\mathcal{M}=\mathbb{S}^4 exists, but unless the field theory is conformal, it is not reflection positive. We derive the Lagrangian for M=S3×R\mathcal{M}=\mathbb{S}^3\times \mathbb{R} and note that the time direction R\mathbb{R} can be rotated to Euclidean signature and be compactified to §1\S^1 only when the theory has a continuous R-symmetry. The partition function on M=S3ק1\mathcal{M}=\mathbb{S}^3\times \S^1 is independent of the parameters of the flat space theory and depends holomorphically on some complex background gauge fields. We also consider R-invariant N=2\mathcal{N}=2 theories on S3\mathbb{S}^3 and clarify a few points about them.Comment: 26 pages, uses harvmac; v2 with added reference

    Combinatorial CRISPR-Cas9 screens for de novo mapping of genetic interactions.

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    We developed a systematic approach to map human genetic networks by combinatorial CRISPR-Cas9 perturbations coupled to robust analysis of growth kinetics. We targeted all pairs of 73 cancer genes with dual guide RNAs in three cell lines, comprising 141,912 tests of interaction. Numerous therapeutically relevant interactions were identified, and these patterns replicated with combinatorial drugs at 75% precision. From these results, we anticipate that cellular context will be critical to synthetic-lethal therapies

    Control and Characterization of Individual Grains and Grain Boundaries in Graphene Grown by Chemical Vapor Deposition

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    The strong interest in graphene has motivated the scalable production of high quality graphene and graphene devices. Since large-scale graphene films synthesized to date are typically polycrystalline, it is important to characterize and control grain boundaries, generally believed to degrade graphene quality. Here we study single-crystal graphene grains synthesized by ambient CVD on polycrystalline Cu, and show how individual boundaries between coalescing grains affect graphene's electronic properties. The graphene grains show no definite epitaxial relationship with the Cu substrate, and can cross Cu grain boundaries. The edges of these grains are found to be predominantly parallel to zigzag directions. We show that grain boundaries give a significant Raman "D" peak, impede electrical transport, and induce prominent weak localization indicative of intervalley scattering in graphene. Finally, we demonstrate an approach using pre-patterned growth seeds to control graphene nucleation, opening a route towards scalable fabrication of single-crystal graphene devices without grain boundaries.Comment: New version with additional data. Accepted by Nature Material

    Patients' opinion on the barriers to diabetes control in areas of conflicts: The Iraqi example

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    <p>Abstract</p> <p>Background</p> <p>The health system in Iraq has undergone progressive decline since the embargo that followed the second gulf war in 1991. The aim of this study is to see barriers to glycemic control form the patient perspective, in a diabetic clinic in the south of Iraq.</p> <p>Methods</p> <p>A cross sectional study from the diabetes out-patient clinic in Al-Faiha general hospital in Basrah, South Iraq for the period from January to December 2007. The study includes diabetic patients whether type 1 or 2 if they have at least one year of follow up in the same clinic. Those with A1C ≥ 7% were interviewed by special questionnaire, that was filled in by the medical staff of the clinic. The subjects analyzed in this study were adults (≥ 18 years old) with previously diagnosed diabetes (n = 3522). The duration of diabetes range from 1 to 30 years.</p> <p>Results</p> <p>Mean A1C was 8.4 ± 2 percent, with 835(23.7%) patients with A1C less than 7% and 2688(76.3%) equal to or more than 7%. Of 3522 studied patients, 46.6% were men and 51.5% were women, with mean age of 53.78 ± 12.81 year and age range 18–97 years. Patient opinion for not achieving good glycemic control among 2688 patients with HbA1C ≥ 7% included the following. No drug supply from primary health care center (PHC) or drug shortage is a cause in 50.8% of cases, while drugs and or laboratory expense were the cause in 50.2%. Thirty point seven percent of patients said that they were unaware of diabetics complications and 20.9% think that diabetes is an untreatable disease. Thirty percent think that non-control of their diabetes is due to migration after the war. No electricity or erratic electricity, self-monitoring of blood glucose (SMBG) is not available, or strips were not available or could not be used, and illiteracy as a cause was seen in 15%, 10.8% and 9.9% respectively.</p> <p>Conclusion</p> <p>Our patients with diabetes mellitus declared that of the causes for poor glycemic control most of them related to the current health situation in Iraq.</p

    Effects of the mu-opioid receptor antagonist GSK1521498 on hedonic and consummatory eating behaviour: a proof of mechanism study in binge-eating obese subjects.

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    The opioid system is implicated in the hedonic and motivational processing of food, and in binge eating, a behaviour strongly linked to obesity. The aim of this study was to evaluate the effects of 4 weeks of treatment with the mu-opioid receptor antagonist GSK1521498 on eating behaviour in binge-eating obese subjects. Adults with body mass index ⩾30 kg m−2 and binge eating scale scores ⩾19 received 1-week single-blind placebo run-in, and were then randomized to 28 days with either 2 mg day−1 GSK1521498, 5 mg day−1 GSK1521498 or placebo (N=21 per arm) in a double-blind parallel group design. The outcome measures were body weight, fat mass, hedonic and consummatory eating behaviour during inpatient food challenges, safety and pharmacokinetics. The primary analysis was the comparison of change scores in the higher-dose treatment group versus placebo using analysis of covariance at each relevant time point. GSK1521498 (2 mg and 5 mg) was not different from placebo in its effects on weight, fat mass and binge eating scores. However, compared with placebo, GSK1521498 5 mg day−1 caused a significant reduction in hedonic responses to sweetened dairy products and reduced calorific intake, particularly of high-fat foods during ad libitum buffet meals, with some of these effects correlating with systemic exposure of GSK1521498. There were no significant effects of GSK1521498 2 mg day−1 on eating behaviour, indicating dose dependency of pharmacodynamics. GSK1521498 was generally well tolerated and no previously unidentified safety signals were detected. The potential for these findings to translate into clinically significant effects in the context of binge eating and weight regain prevention requires further investigation

    Absence of system xc⁻ on immune cells invading the central nervous system alleviates experimental autoimmune encephalitis

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    Background: Multiple sclerosis (MS) is an autoimmune demyelinating disease that affects the central nervous system (CNS), leading to neurodegeneration and chronic disability. Accumulating evidence points to a key role for neuroinflammation, oxidative stress, and excitotoxicity in this degenerative process. System x(c)- or the cystine/glutamate antiporter could tie these pathological mechanisms together: its activity is enhanced by reactive oxygen species and inflammatory stimuli, and its enhancement might lead to the release of toxic amounts of glutamate, thereby triggering excitotoxicity and neurodegeneration. Methods: Semi-quantitative Western blotting served to study protein expression of xCT, the specific subunit of system x(c)-, as well as of regulators of xCT transcription, in the normal appearing white matter (NAWM) of MS patients and in the CNS and spleen of mice exposed to experimental autoimmune encephalomyelitis (EAE), an accepted mouse model of MS. We next compared the clinical course of the EAE disease, the extent of demyelination, the infiltration of immune cells and microglial activation in xCT-knockout (xCT(-/-)) mice and irradiated mice reconstituted in xCT(-/-) bone marrow (BM), to their proper wild type (xCT(+/+)) controls. Results: xCT protein expression levels were upregulated in the NAWM of MS patients and in the brain, spinal cord, and spleen of EAE mice. The pathways involved in this upregulation in NAWM of MS patients remain unresolved. Compared to xCT(+/+) mice, xCT(-/-) mice were equally susceptible to EAE, whereas mice transplanted with xCT(-/-) BM, and as such only exhibiting loss of xCT in their immune cells, were less susceptible to EAE. In none of the above-described conditions, demyelination, microglial activation, or infiltration of immune cells were affected. Conclusions: Our findings demonstrate enhancement of xCT protein expression in MS pathology and suggest that system x(c)- on immune cells invading the CNS participates to EAE. Since a total loss of system x(c)- had no net beneficial effects, these results have important implications for targeting system x(c)- for treatment of MS

    Similar dispersal patterns between two closely related birds with contrasting migration strategies

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    Studying dispersal is crucial to understand metapopulation and sink-source dynamics and invasion processes. The capability to disperse is especially important for species living in fragmented habitats like wetlands. We investigated the distribution of natal and breeding dispersal distances and philopatry in Spanish populations of two closely related reedbed-nesting birds, the Moustached Warbler Acrocephalus melanopogon and the Eurasian Reed Warbler Acrocephalus scirpaceus. These warblers are morphologically very similar, but differ in migration strategy and, in our study area, in population size. Our aims were to find the best model for dispersal distances and to assess the occurrence of intra- or interspecific differences in dispersal patterns. We used ringing data from the Spanish marking scheme and selected recaptures to avoid including migrating individuals. In both species, most individuals were philopatric but dispersing birds were able to cross large distances (up to more than 100 km), suggesting the capability to compensate for habitat fragmentation. We found the heavy-tailed Cauchy distribution to be the best conceptual description for our data, in all cases but natal dispersal of Moustached Warblers. Among Eurasian Reed Warblers, natal philopatry was lower than breeding philopatry. We found no significant interspecific differences. This does not confirm the hypothesis of higher dispersal ability in long distance migrants (like Eurasian Reed Warblers) than in resident/short distance migrant bird species (like Moustached Warblers). The similarity in dispersal patterns among the two warblers may be explained by their close phylogenetic relatedness, similar constraints imposed on both species by a patchy habitat or similar evolutionary pressures.We are grateful to the many ringers who collected the data during years of fieldwork in Spain. Francesco Ceresa is supported by an "Atraent talent'' grant from the University of Valencia.Ceresa, F.; Belda, E.; Monrós González, JS. (2016). Similar dispersal patterns between two closely related birds with contrasting migration strategies. Population Ecology. 58(3):421-427. doi:10.1007/s10144-016-0547-0S421427583Banco de datos de anillamiento del remite ICONA – Ministerio de Medio Ambiente (2015) Datos de anillamiento y recuperaciones en España. Ministerio de Agricultura, Alimentación y Medio Ambiente, SEO/BirdLife, ICO, EBD-CSIC y GOB. Madrid (in Spanish)Begon M, Townsend CR, Harper JL (2006) Ecology: from individual to ecosystems, 4th edn. Blackwell Publishing, OxfordBlomqvist D, Fessl B, Hoi H, Kleindorfer S (2005) High frequency of extra-pair fertilisation in the moustached warbler, a songbird with a variable breeding system. Behaviour 142:1133–1148Bohonak AJ (1999) Dispersal, gene flow, and population structure. Q Rev Biol 74:21–45Burnham KP, Anderson DR (2002) Model selection and multi-model inference: a practical information-theoretic approach. Springer Verlag, New YorkCantos FJ, Tellería JL (1994) Stopover site fidelity of four migrant warblers in the Iberian Peninsula. J Avian Biol 25:131–134Carrascal LM, Palomino D (2008) Las aves comunes reproductoras en España. Población en 2004–2006. SEO/BirdLife, Madrid (in Spanish with English abstract)Carrascal LM, Weykam S, Palomino D, Lobo JM, Díaz L (2005) Atlas Virtual de las Aves Terrestres de España. http://www.vertebradosibericos.org/atlasaves.html . Accessed 16 Feb 2016Castany J (2003) El carricerín real (Acrocephalus melanopogon) en el P. N. del Prat de Cabanes-Torreblanca. Doctoral thesis. University of Valencia, Valencia (in Spanish)Castany J, López G (2006) El carricerín real en España. I Censo Nacional (2005). SEO/BirdLife, Madrid (in Spanish with English abstract)Ceresa F, Belda EJ, Kvist L, Rguibi-Idrissi H, Monrós JS (2015) Does fragmentation of wetlands affect gene flow in sympatric Acrocephalus warblers with different migration strategies? J Avian Biol 46:577–588Cooper NW, Murphy MT, Redmond LJ, Dolan AC (2009) Density-dependent age at first reproduction in the eastern kingbird. Oikos 118:413–419Delignette-Muller ML, Dutang C (2015) fitdistrplus: An R Package for fitting distributions. J Stat Softw 64:1–34. http://www.jstatsoft.org/v64/i04/ . Accessed 2 Sep 2015Frankham R, Ballou JD, Briscoe DA (2010) Introduction to conservation genetics, 2nd edn. Cambridge University Press, CambridgeHengeveld R (1994) Small step invasion research. Trends Ecol Evol 9:339–342Hodges MF Jr, Krementz DG (1996) Neotropical migratory breeding bird communities in riparian forests of different widths along the Altamaha River, Georgia. Wilson Bulletin 108:496–506Ibrahim KM, Nichols RA, Hewitt GM (1996) Spatial patterns of genetic variation generated by different forms of dispersal during range expansion. Heredity 77:282–291Kennerley P, Pearson D (2010) Reed and bush warblers. Christopher Helm Publishers Ltd., LondonKoenig WD, Van Vuren D, Hooge PN (1996) Detectability, philopatry, and the distribution of dispersal distances in vertebrates. Trends Ecol Evol 11:514–517Kralj J, Procházka P, Fainová D, Patzenhauerová H, Tutiš V (2010) Intraspecific variation in the wing shape and genetic differentiation of reed warblers Acrocephalus scirpaceus in Croatia. Acta Ornithologica 45:51–58Lambrechts MM, Blondel J, Caizergues A, Dias PC, Pradol R, Thomas DW (1999) Will estimates of lifetime recruitment of breeding offspring on small-scale study plots help us to quantify processes underlying adaptation? Oikos 86:147–151Machtans CS, Villard MA, Hannon SJ (1996) Use of riparian buffer strips as movement corridors by forest birds. Conserv Biol 10:1366–1379Nathan R, Perry G, Cronin JT, Strand AE, Cain ML (2003) Methods for estimating long-distance dispersal. Oikos 103:261–273Newton I (1992) Experiments on the limitation of bird numbers by territorial behaviour. Biol Rev 67:129–173Norberg UM (1990) Vertebrate flight, mechanics, physiology, morphology, ecology and evolution. Springer Verlag, BerlinParacuellos M, Tellería JL (2004) Factors affecting the distribution of a waterbird community: the role of habitat configuration and bird abundance. Waterbirds 27:446–453Paradis E, Baillie SR, Sutherland WJ, Gregory RD (1998) Patterns of natal and breeding dispersal in birds. J Anim Ecol 67:518–536Paradis E, Baillie SR, Sutherland WJ (2002) Modeling large-scale dispersal distances. Ecol Model 151:279–292Peirò IG (2003) Intraspecific variation in the wing shape of the long-distance migrant Reed Warbler Acrocephalus scirpaceus: effects of age and distance of migration. Ardeola 50:31–37Plissner JH, Gowaty PA (1996) Patterns of natal dispersal, turnover, and dispersal costs in eastern bluebirds. Anim Behav 51:1307–1322Procházka P, Stokke BG, Jensen H, Fainová D, Bellinvia E, Fossøy F, Vikan JR, Bryja J, Soler M (2011) Low genetic differentiation among reed warbler Acrocephalus scirpaceus populations across Europe. J Avian Biol 42:103–113R Core Team (2014) R: A language and environment for statistical computing. R foundation for statistical computing, ViennaRobinson WD (1999) Long-term changes in the avifauna of Barro Colorado Island, Panama, a tropical forest isolate. Conserv Biol 13:85–97SEO/BirdLife (2016a) Acrocephalus melanopogon. Anillamientos por década. http://www.anillamientoseo.org/ . Accessed 19 Feb 2016 (in Spanish)SEO/BirdLife (2016b) Acrocephalus scirpaceus. Anillamientos por década. http://www.anillamientoseo.org/ . Accessed 19 Feb 2016 (in Spanish)Shigesada N, Kawasaki K, Takeda Y (1995) Modeling stratified diffusion in biological invasions. Am Nat 146:229–251Silva JP, Phillips L, Jones W, Eldridge J, O’Hara E (2007) Life and Europe’s wetlands, restoring a vital ecosystem. Office for Official Publications of the European Communities, LuxembourgSutherland GD, Harestad AS, Price K, Lertzman KP (2000) Scaling of natal dispersal distances in terrestrial birds and mammals. Conservation ecology 4:16. http://www.consecol.org/vol4/iss1/art16 . Accessed 23 Oct 2015Vadász C, Német Á, Karcza Z, Loránt M, Biró C, Csörgő T (2008) Study on breeding site fidelity of Acrocephalus Warblers in Central Hungary. Acta Zool Acad Sci H 54(Suppl. 1):167–175Van Houtan KS, Pimm SL, Halley JM, Bierregaard RO Jr, Lovejoy TE (2007) Dispersal of Amazonian birds in continuous and fragmented forest. Ecol Lett 10:219–229Van Houtan KS, Bass OL Jr, Lockwood J, Pimm SL (2010) Importance of estimating dispersal for endangered bird management. Conservation Letters 3:260–266Van Vessem J, Hecker N, Tucker GM (1997) Inland wetlands. In: Tucker GM, Evans MI (eds) Habitats for birds in Europe: A conservation strategy for the wider environment. BirdLife Conservation Series 6. BirdLife International, Cambridge, pp 125–158Waser PM, Creel SR, Lucas JR (1994) Death and disappearance: estimating mortality risk associated with philopatry and dispersal. Behav Ecol 5:135–141Willis EO (1974) Populations and local extinctions of birds on Barro Colorado Island, Panama. Ecol Monogr 44:153–169Winkler DW, Wrege PH, Allen PE, Kast TL, Senesac P, Wasson MF, Llambías PE, Ferretti V, Sullivan PJ (2004) Breeding dispersal and philopatry in the tree swallow. Condor 106:768–776Winkler DW, Wrege PH, Allen PE, Kast TL, Senesac P, Wasson MF, Sullivan PJ (2005) The natal dispersal of tree swallows in a continuous mainland environment. J Anim Ecol 74:1080–109
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