864 research outputs found
Yukawa Unification and the Superpartner Mass Scale
Naturalness in supersymmetry (SUSY) is under siege by increasingly stringent
LHC constraints, but natural electroweak symmetry breaking still remains the
most powerful motivation for superpartner masses within experimental reach. If
naturalness is the wrong criterion then what determines the mass scale of the
superpartners? We motivate supersymmetry by (1) gauge coupling unification, (2)
dark matter, and (3) precision b-tau Yukawa unification. We show that for an
LSP that is a bino-Higgsino admixture, these three requirements lead to an
upper-bound on the stop and sbottom masses in the several TeV regime because
the threshold correction to the bottom mass at the superpartner scale is
required to have a particular size. For tan beta about 50, which is needed for
t-b-tau unification, the stops must be lighter than 2.8 TeV when A_t has the
opposite sign of the gluino mass, as is favored by renormalization group
scaling. For lower values of tan beta, the top and bottom squarks must be even
lighter. Yukawa unification plus dark matter implies that superpartners are
likely in reach of the LHC, after the upgrade to 14 (or 13) TeV, independent of
any considerations of naturalness. We present a model-independent, bottom-up
analysis of the SUSY parameter space that is simultaneously consistent with
Yukawa unification and the hint for m_h = 125 GeV. We study the flavor and dark
matter phenomenology that accompanies this Yukawa unification. A large portion
of the parameter space predicts that the branching fraction for B_s to mu^+
mu^- will be observed to be significantly lower than the SM value.Comment: 34 pages plus appendices, 20 figure
A new approach for obtaining rapid uniformity in rice (Oryza sativa L.) via a 3x x 2x cross
A triploid (2n = 3x = 36) rice plant was obtained by screening a twin seedling population in which each seed germinated to two or three sprouts that were then crossed with diploid plants. One diploid plant was chosen among the various F1 progenies and developed into an F 2 population via self-pollination. Compared with the control variety Shanyou 63, this F 2 population had a stable agronomical performance in field trials, as confirmed by the F-test. The stability of the F 2 population was further substantiated by molecular analysis with simple sequence repeat markers. Specifically, of 160 markers assayed, 37 (covering all 12 chromosomes) were polymorphic between the parental lines. Testing the F 1 hybrid individually with these markers showed that each PCR product had only a single band instead of two bands from each parent. The bands were identical to either maternal (23 markers) or paternal (eight markers) bands or distinct from both parents (six markers). The amplified bands of all 60 randomly selected F 2 plants were uniform and identical to those of the F 1 hybrid. These results suggest that the F 1 plant is a non-segregating hybrid and that a stable F 2 population was obtained. This novel system provides an efficient means for shortening the cycle of hybrid rice seed production
Minimal flavour violation extensions of the seesaw
We analyze the most natural formulations of the minimal lepton flavour
violation hypothesis compatible with a type-I seesaw structure with three heavy
singlet neutrinos N, and satisfying the requirement of being predictive, in the
sense that all LFV effects can be expressed in terms of low energy observables.
We find a new interesting realization based on the flavour group (being and respectively the SU(2) singlet and
doublet leptons). An intriguing feature of this realization is that, in the
normal hierarchy scenario for neutrino masses, it allows for sizeable
enhancements of transitions with respect to LFV processes involving
the lepton. We also discuss how the symmetries of the type-I seesaw
allow for a strong suppression of the N mass scale with respect to the scale of
lepton number breaking, without implying a similar suppression for possible
mechanisms of N productionComment: 14 pages, 6 figure
Band Alignments, Electronic Structure, and Core-Level Spectra of Bulk Molybdenum Dichalcogenides (MoS<inf>2</inf>, MoSe<inf>2</inf>, and MoTe<inf>2</inf>)
A comprehensive study of bulk molybdenum dichalcogenides is presented with the use of soft and hard X-ray photoelectron (SXPS and HAXPES) spectroscopy combined with hybrid density functional theory (DFT). The main core levels of MoS2, MoSe2, and MoTe2 are explored. Laboratory-based X-ray photoelectron spectroscopy (XPS) is used to determine the ionization potential (IP) values of the MoX2 series as 5.86, 5.40, and 5.00 eV for MoSe2, MoSe2, and MoTe2, respectively, enabling the band alignment of the series to be established. Finally, the valence band measurements are compared with the calculated density of states which shows the role of p-d hybridization in these materials. Down the group, an increase in the p-d hybridization from the sulfide to the telluride is observed, explained by the configuration energy of the chalcogen p orbitals becoming closer to that of the valence Mo 4d orbitals. This pushes the valence band maximum closer to the vacuum level, explaining the decreasing IP down the series. High-resolution SXPS and HAXPES core-level spectra address the shortcomings of the XPS analysis in the literature. Furthermore, the experimentally determined band alignment can be used to inform future device work
Repressing Anarchy in Neutrino Mass Textures
The recent results that is relatively large, of the order of
the previous upper bound, and the indications of a sizable deviation of
from the maximal value are in agreement with the predictions of
Anarchy in the lepton sector. The quark and charged lepton hierarchies can then
be reproduced in a SU(5) GUT context by attributing non-vanishing
charges, different for each family, only to the SU(5) tenplet states. The fact
that the observed mass hierarchies are stronger for up quarks than for down
quarks and charged leptons supports this idea. As discussed in the past, in the
flexible context of , different patterns of charges can
be adopted going from Anarchy to various types of hierarchy. We revisit this
approach by also considering new models and we compare all versions to the
present data. As a result we confirm that, by relaxing the extreme ansatz of
equal charges for all SU(5) pentaplets and singlets, better
agreement with the data than for Anarchy is obtained without increasing the
model complexity. We also present the distributions obtained in the different
models for the Dirac CP-violating phase. Finally we discuss the relative merits
of these simple models.Comment: v1: 12 pages, 3 figures; v2: 13 pages, 3 figures, text improved,
matches version accepted for publication; v3: submitted to add an
acknowledgment to a networ
A habituation account of change detection in same/different judgments
We investigated the basis of change detection in a short-term priming task. In two experiments, participants were asked to indicate whether or not a target word was the same as a previously presented cue. Data from an experiment measuring magnetoencephalography failed to find different patterns for “same” and “different” responses, consistent with the claim that both arise from a common neural source, with response magnitude defining the difference between immediate novelty versus familiarity. In a behavioral experiment, we tested and confirmed the predictions of a habituation account of these judgments by comparing conditions in which the target, the cue, or neither was primed by its presentation in the previous trial. As predicted, cue-primed trials had faster response times, and target-primed trials had slower response times relative to the neither-primed baseline. These results were obtained irrespective of response repetition and stimulus–response contingencies. The behavioral and brain activity data support the view that detection of change drives performance in these tasks and that the underlying mechanism is neuronal habituation
O-GlcNAc Modification of NFκB p65 Inhibits TNF-α-Induced Inflammatory Mediator Expression in Rat Aortic Smooth Muscle Cells
BACKGROUND: We have shown that glucosamine (GlcN) or O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino-N-phenylcarbamate (PUGNAc) treatment augments O-linked-N-acetylglucosamine (O-GlcNAc) protein modification and attenuates inflammatory mediator expression, leukocyte infiltration and neointima formation in balloon injured rat carotid arteries and have identified the arterial smooth muscle cell (SMC) as the target cell in the injury response. NFκB signaling has been shown to mediate the expression of inflammatory genes and neointima formation in injured arteries. Phosphorylation of the p65 subunit of NFκB is required for the transcriptional activation of NFκB. This study tested the hypothesis that GlcN or PUGNAc treatment protects vascular SMCs against tumor necrosis factor (TNF)-α induced inflammatory stress by enhancing O-GlcNAcylation and inhibiting TNF-α induced phosphorylation of NFκB p65, thus inhibiting NFκB signaling. METHODOLOGY/PRINCIPAL FINDINGS: Quiescent rat aortic SMCs were pretreated with GlcN (5 mM), PUGNAc (10(-4) M) or vehicle and then stimulated with TNF-α (10 ng/ml). Both treatments inhibited TNF-α-induced expression of chemokines [cytokine-induced neutrophil chemoattractant (CINC)-2β and monocyte chemotactic protein (MCP)-1] and adhesion molecules [vascular cell adhesion molecule (VCAM)-1 and P-Selectin]. Both treatments inhibited TNF-α induced NFκB p65 activation and promoter activity, increased NFκB p65 O-GlcNAcylation and inhibited NFκB p65 phosphorylation at Serine 536, thus promoting IκBα binding to NFκB p65. CONCLUSIONS: There is a reciprocal relationship between O-GlcNAcylation and phosphorylation of NFκB p65, such that increased NFκB p65 O-GlcNAc modification inhibits TNF-α-Induced expression of inflammatory mediators through inhibition of NFκB p65 signaling. These findings provide a mechanistic basis for our previous observations that GlcN and PUGNAc treatments inhibit inflammation and remodeling induced by acute endoluminal arterial injury
Caveolin-1 protects B6129 mice against Helicobacter pylori gastritis.
Caveolin-1 (Cav1) is a scaffold protein and pathogen receptor in the mucosa of the gastrointestinal tract. Chronic infection of gastric epithelial cells by Helicobacter pylori (H. pylori) is a major risk factor for human gastric cancer (GC) where Cav1 is frequently down-regulated. However, the function of Cav1 in H. pylori infection and pathogenesis of GC remained unknown. We show here that Cav1-deficient mice, infected for 11 months with the CagA-delivery deficient H. pylori strain SS1, developed more severe gastritis and tissue damage, including loss of parietal cells and foveolar hyperplasia, and displayed lower colonisation of the gastric mucosa than wild-type B6129 littermates. Cav1-null mice showed enhanced infiltration of macrophages and B-cells and secretion of chemokines (RANTES) but had reduced levels of CD25+ regulatory T-cells. Cav1-deficient human GC cells (AGS), infected with the CagA-delivery proficient H. pylori strain G27, were more sensitive to CagA-related cytoskeletal stress morphologies ("humming bird") compared to AGS cells stably transfected with Cav1 (AGS/Cav1). Infection of AGS/Cav1 cells triggered the recruitment of p120 RhoGTPase-activating protein/deleted in liver cancer-1 (p120RhoGAP/DLC1) to Cav1 and counteracted CagA-induced cytoskeletal rearrangements. In human GC cell lines (MKN45, N87) and mouse stomach tissue, H. pylori down-regulated endogenous expression of Cav1 independently of CagA. Mechanistically, H. pylori activated sterol-responsive element-binding protein-1 (SREBP1) to repress transcription of the human Cav1 gene from sterol-responsive elements (SREs) in the proximal Cav1 promoter. These data suggested a protective role of Cav1 against H. pylori-induced inflammation and tissue damage. We propose that H. pylori exploits down-regulation of Cav1 to subvert the host's immune response and to promote signalling of its virulence factors in host cells
Characterization of PERV in a new conserved pig herd as potential donor animals for xenotransplantation in China
Spontaneous R-Parity Violation, Flavor Symmetry and Tribimaximal Mixing
We explore the possibility of spontaneous R parity violation in the context
of flavor symmetry. Our model contains singlet matter chiral superfields which are arranged as triplet of
and as well as few additional Higgs chiral superfields which are singlet
under MSSM gauge group and belong to triplet and singlet representation under
the flavor symmetry. R parity is broken spontaneously by the vacuum
expectation values of the different sneutrino fields and hence we have
neutrino-neutralino as well as neutrino-MSSM gauge singlet higgsino mixings in
our model, in addition to the standard model neutrino- gauge singlet neutrino,
gaugino-higgsino and higgsino-higgsino mixings. Because all of these mixings we
have an extended neutral fermion mass matrix. We explore the low energy
neutrino mass matrix for our model and point out that with some specific
constraints between the sneutrino vacuum expectation values as well as the MSSM
gauge singlet Higgs vacuum expectation values, the low energy neutrino mass
matrix will lead to a tribimaximal mixing matrix. We also analyze the potential
minimization for our model and show that one can realize a higher vacuum
expectation value of the singlet
sneutrino fields even when the other sneutrino vacuum expectation values are
extremely small or even zero.Comment: 18 page
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