935 research outputs found

    An Effect of α′\alpha' Corrections on Racetrack Inflation

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    We study the effects of α′ \alpha ' corrections to the K\"ahler potential on volume stabilisation and racetrack inflation. In a region where classical supergravity analysis is justified, stringy corrections can nevertheless be relevant for correctly analyzing moduli stabilisation and the onset of inflation.Comment: 13 pages, 4 figures. Typos corrected, references added, this version to appear in JHE

    On 'Light' Fermions and Proton Stability in 'Big Divisor' D3/D7 Swiss Cheese Phenomenology

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    Building up on our earlier work [1,2], we show the possibility of generating "light" fermion mass scales of MeV-GeV range (possibly related to first two generations of quarks/leptons) as well as eV (possibly related to first two generations of neutrinos) in type IIB string theory compactified on Swiss-Cheese orientifolds in the presence of a mobile space-time filling D3-$brane restricted to (in principle) stacks of fluxed D7-branes wrapping the "big" divisor \Sigma_B. This part of the paper is an expanded version of the latter half of section 3 of a published short invited review [3] written up by one of the authors [AM]. Further, we also show that there are no SUSY GUT-type dimension-five operators corresponding to proton decay, as well as estimate the proton lifetime from a SUSY GUT-type four-fermion dimension-six operator to be 10^{61} years. Based on GLSM calculations in [1] for obtaining the geometric Kaehler potential for the "big divisor", using further the Donaldson's algorithm, we also briefly discuss in the first of the two appendices, obtaining a metric for the Swiss-Cheese Calabi-Yau used, that becomes Ricci flat in the large volume limit.Comment: v2: 1+25 pages, Title modified and text thoroughly expanded including a brief discussion on obtaining Ricci-flat Swiss Cheese Calabi-Yau metrics using the Donaldson's algorithm, references added, to appear in EPJ

    Biochemical parameters of silver catfish (Rhamdia quelen) after transport with eugenol or essential oil of Lippia alba added to the water

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    The transport of live fish is a routine practice in aquaculture and constitutes a considerable source of stress to the animals. The addition of anesthetic to the water used for fish transport can prevent or mitigate the deleterious effects of transport stress. This study investigated the effects of the addition of eugenol (EUG) (1.5 or 3.0 mu L L-1) and essential oil of Lippia alba (EOL) (10 or 20 mu L L-1) on metabolic parameters (glycogen, lactate and total protein levels) in liver and muscle, acetylcholinesterase activity (AChE) in muscle and brain, and the levels of protein carbonyl (PC), thiobarbituric acid reactive substances (TBARS) and nonprotein thiol groups (NPSH) and activity of glutathione-S-transferase in the liver of silver catfish (Rhamdia quelen; Quoy and Gaimard, 1824) transported for four hours in plastic bags (loading density of 169.2 g L-1). The addition of various concentrations of EUG (1.5 or 3.0 mu L L-1) and EOL (10 or 20 mu L L-1) to the transport water is advisable for the transportation of silver catfish, since both concentrations of these substances increased the levels of NPSH antioxidant and decreased the TBARS levels in the liver. In addition, the lower liver levels of glycogen and lactate in these groups and lower AChE activity in the brain (EOL 10 or 20 mu L L-1) compared to the control group indicate that the energetic metabolism and neurotransmission were lower after administration of anesthetics, contributing to the maintenance of homeostasis and sedation status.Fundacao de Amparo a Pesquisa do Estado do Rio Grande do Sul (FAPERGS/PRONEX) [10/0016-8]; Conselho Nacional de Pesquisa e Desenvolvimento Cientifico (CNPq) [470964/2009-0]; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); CNPqinfo:eu-repo/semantics/publishedVersio

    Energy landscape of relaxed amorphous silicon

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    We analyze the structure of the energy landscape of a well-relaxed 1000-atom model of amorphous silicon using the activation-relaxation technique (ART nouveau). Generating more than 40,000 events starting from a single minimum, we find that activated mechanisms are local in nature, that they are distributed uniformly throughout the model and that the activation energy is limited by the cost of breaking one bond, independently of the complexity of the mechanism. The overall shape of the activation-energy-barrier distribution is also insensitive to the exact details of the configuration, indicating that well-relaxed configurations see essentially the same environment. These results underscore the localized nature of relaxation in this material.Comment: 8 pages, 12 figure

    Prenatal Tdap immunization and risk of maternal and newborn adverse events

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    Many countries recommend combined tetanus toxoid, reduced diphtheria toxoid and acellular pertussis immunization (Tdap) during pregnancy to stimulate transplacental transmission of pertussis antibodies to newborns. The immune system can be altered during pregnancy, potentially resulting in differing immunization risks in pregnant women. The safety of widespread Tdap immunization during pregnancy needs to be established. Our objective was to assess whether prenatal Tdap immunization was associated with adverse birth outcomes, and to evaluate the effect of timing of Tdap administration on these outcomes. We identified pregnancies at delivery in a large insurance claims database (2010–2014). Tdap immunization was categorized as optimal prenatal (27 + weeks), early prenatal (<27 weeks), postpartum (≤7 days post-delivery), or none. Medical claims were searched to identify maternal adverse immunization reactions (e.g. anaphylaxis, fever, Guillian-Barre syndrome [GBS]), adverse birth outcomes (e.g. preeclampsia/eclampsia, premature rupture or membranes, chorioamnionitis) and newborn outcomes (e.g. respiratory distress, pulmonary hypertension, neonatal jaundice). Women with optimal or early prenatal Tdap were compared to those not immunized in pregnancy, using propensity score-weighted log-binomial regression and Cox proportional hazards models to estimate risk ratios (RR) and hazard ratios (HR). We identified 1,079,034 deliveries and 677,075 linked newborns; 11.5% were immunized optimally and 2.3% immunized early. There were 1 case of post-immunization anaphylaxis, and 12 cases of maternal encephalopathy (all post- delivery); there were no cases of GBS. Optimally-timed immunization was associated with small increased relative risks of: chorioamnionitis [RR = 1.11, (95% CI: 1.07–1.15), overall risk = 2.8%], and postpartum hemorrhage [RR = 1.23 (95% DI: 1.18–1.28), overall risk = 2.4%]; however, these relative increases corresponded to low absolute risk increases. Tdap was not associated with increased risk of any adverse newborn outcome. Overall, prenatal Tdap immunization was not associated with newborn adverse events, but potential associations with chorioamnionitis consistent with one previous study and postpartum hemorrhage require further investigation

    On the complete classification of the unitary N=2 minimal superconformal field theories

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    Aiming at a complete classification of unitary N=2 minimal models (where the assumption of space-time supersymmetry has been dropped), it is shown that each modular invariant candidate of a partition function for such a theory is indeed the partition function of a minimal model. A family of models constructed via orbifoldings of either the diagonal model or of the space-time supersymmetric exceptional models demonstrates that there exists a unitary N=2 minimal model for every one of the allowed partition functions in the list obtained from Gannon's work. Kreuzer and Schellekens' conjecture that all simple current invariants can be obtained as orbifolds of the diagonal model, even when the extra assumption of higher-genus modular invariance is dropped, is confirmed in the case of the unitary N=2 minimal models by simple counting arguments.Comment: 53 pages; Latex; minor changes in v2: intro expanded, references added, typos corrected, footnote added on p31; renumbering of sections; main theorem reformulated for clarity, but contents unchanged. Minor revisions in v3: typos corrected, footnotes 5, 6 added, lemma 1 and section 3.3.2 rewritten for greater generality, section 3.3 review removed. To appear in Comm. Math. Phy

    Effectiveness of Prenatal Tetanus, Diphtheria, Acellular Pertussis Vaccination in the Prevention of Infant Pertussis in the U.S.

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    Introduction: It is recommended that all pregnant women in the U.S. receive tetanus, diphtheria, acellular pertussis (Tdap) immunization to prevent infant pertussis. This study's objective was to examine the clinical effectiveness of prenatal Tdap, and whether effectiveness varies by gestational age at immunization. Methods: A nationwide cohort study of pregnant women with deliveries in 2010–2014 and their infants was performed. Commercial insurance claims data were analyzed in 2016–2017 to identify Tdap receipt by the pregnant women, and hospitalizations and outpatient visits for pertussis in their infants until the infants reached 18 months of age. Pertussis occurrence was compared between infants of mothers who received prenatal Tdap (overall and stratified by gestational age at administration) and infants of unvaccinated mothers. Results: There were 675,167 mother–infant pairs in the cohort. Among infants whose mothers received prenatal Tdap, the rate of pertussis was 43% lower (hazard ratio=0.57, 95% CI=0.35, 0.92) than infants whose mothers did not receive prenatal or postpartum Tdap; this reduction was consistent across pertussis definitions (hazard ratio for inpatient-only pertussis=0.32, 95% CI=0.11, 0.91). Pertussis rates were also lower for infants whose mothers received Tdap during the third trimester. Infants whose mothers received Tdap at <27 weeks of gestation did not experience reductions in pertussis rates (hazard ratio for pertussis=1.10, 95% CI=0.54, 2.25). Conclusions: Infants of mothers who received prenatal Tdap experienced half the rate of pertussis as compared with infants of unimmunized mothers. These results do not provide evidence to support changing the currently recommended timing of Tdap administration in pregnancy

    Predictors of low uptake of prenatal tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis immunization in privately insured women in the United States

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    OBJECTIVE: To examine the uptake of prenatal tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) immunization among pregnant women in the United States. METHODS: Using MarketScan data, we conducted a historical cohort study among pregnant women with employer-based commercial insurance in the United States who delivered between January 1, 2010, and December 31, 2014. We examined temporal trends of uptake, predictors of uptake, and timing of Tdap immunization. RESULTS: Among 1,222,384 eligible pregnancies in 1,147,711 women, receipt of prenatal Tdap immunization increased from 0.0% of women who delivered in January 2010 to 9.8% who delivered in October 2012 (the date of the recommendation by the Advisory Committee on Immunization Practices for Tdap during every pregnancy) to 44.4% who delivered in December 2014. Among women who received Tdap during pregnancy, the majority were immunized between 27 weeks and 36 6/7 weeks of gestation per the Advisory Committee on Immunization Practices recommendation. In multivariable analyses among women who delivered between November 2012 and December 2014, rates of prenatal Tdap immunization were lower for women younger than 25 years of age (eg, 20-24 compared with 30-34 years rate ratio [RR] 0.83, 95% confidence interval [CI] 0.85-0.88), with other children (eg, three compared with zero children: RR 0.86, 95% CI 0.84-0.88), residing in the South compared with the Midwest (RR 0.81, 95% CI 0.80-0.82), or with emergency department visits in early pregnancy (RR 0.93, 95% CI 0.92-0.95). The proportion of pregnant women who received prenatal Tdap increased with increasing gestational age at birth. CONCLUSION: By the end of 2014, fewer than half of pregnant women in the United States were receiving prenatal Tdap immunization. Implementation and dissemination strategies are needed to increase Tdap coverage among pregnant women, especially those who are young, have other children, or reside in the South

    Product-Group Unification in Type IIB String Thoery

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    The product-group unification is a model of unified theories, in which masslessness of the two Higgs doublets and absence of dimension-five proton decay are guaranteed by a symmetry. It is based on SU(5) x U(N) (N=2,3) gauge group. It is known that various features of the model are explained naturally, when it is embedded in a brane world. This article describes an idea of how to accommodate all the particles of the model in Type IIB brane world. The GUT-breaking sector is realized by a D3--D7 system, and chiral quarks and leptons arise from intersection of D7-branes. The D-brane configuration can be a geometric realization of the non-parallel family structure of quarks and leptons, an idea proposed to explain the large mixing angles observed in the neutrino oscillation. The tri-linear interaction of the next-to-minimal supersymmetric standard model is obtained naturally in some cases.Comment: 33 pages, 5 figure

    Probing neutrino non-standard interactions with atmospheric neutrino data

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    We have reconsidered the atmospheric neutrino anomaly in light of the laetst data from Super-Kamiokande contained events and from Super-Kamiokande and MACRO up-going muons. We have reanalysed the proposed solution to the atmospheric neutrino anomaly in terms of non-standard neutrino-matter interactions (NSI) as well as the standard nu_mu -> nu_tau oscillations (OSC). Our statistical analysis shows that a pure NSI mechanism is now ruled out at 99%, while the standard nu_mu -> nu_tau OSC mechanism provides a quite remarkably good description of the anomaly. We therefore study an extended mechanism of neutrino propagation which combines both oscillation and non-standard neutrino-matter interactions, in order to derive limits on flavour-changing (FC) and non-universal (NU) neutrino interactions. We obtain that the off-diagonal flavour-changing neutrino parameter epsilon and the diagonal non-universality neutrino parameter epsilon' are confined to -0.03 < epsilon < 0.02 and |epsilon'| < 0.05 at 99.73% CL. These limits are model independent and they are obtained from pure neutrino-physics processes. The stability of the neutrino oscillation solution to the atmospheric neutrino anomaly against the presence of non-standard neutrino interactions establishes the robustness of the near-maximal atmospheric mixing and massive-neutrino hypothesis. The best agreement with the data is obtained for Delta_m^2 = 2.3*10^{-3} eV^2, sin^2(2*theta) = 1, epsilon = 6.7*10^{-3} and epsilon' = 1.1*10^{-3}, although the chi^2 function is quite flat in the epsilon and epsilon' directions for epsilon, epsilon' -> 0.Comment: 26 pages, LaTeX file using REVTeX4, 1 table and 12 figures included. Added a revised analysis which takes into account the new 1489-day Super-Kamiokande and final MACRO data. The bound on NSI parameters is considerably improve
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