Long-Lived Neutralino NLSPs

We investigate the collider signatures of heavy, long-lived, neutral particles that decay to charged particles plus missing energy. Specifically, we focus on the case of a neutralino NLSP decaying to Z and gravitino within the context of General Gauge Mediation. We show that a combination of searches using the inner detector and the muon spectrometer yields a wide range of potential early LHC discoveries for NLSP lifetimes ranging from 10^(-1)-10^5 mm. We further show that events from Z(l+l-) can be used for detailed kinematic reconstruction, leading to accurate determinations of the neutralino mass and lifetime. In particular, we examine the prospects for detailed event study at ATLAS using the ECAL (making use of its timing and pointing capabilities) together with the TRT, or using the muon spectrometer alone. Finally, we also demonstrate that there is a region in parameter space where the Tevatron could potentially discover new physics in the delayed Z(l+l-)+MET channel. While our discussion centers on gauge mediation, many of the results apply to any scenario with a long-lived neutral particle decaying to charged particles.Comment: 31 pages, 12 figure

The acute muscular response to two distinct blood flow restriction protocols

The purpose of this study was to determine acute physiological and perceptual responses to two commonly implemented blood flow restriction protocols. Using a within-subject design, 15 participants (age ∼25) performed four sets of unilateral elbow flexion with each arm. One arm exercised using a 3-cm elastic cuff inflated to 160 mmHg, whereas the other arm exercised using a 5-cm nylon cuff inflated to 40% of the individual’s arterial occlusion pressure. While both protocols elicited increases in acute muscle thickness [pre: 4.5 (0.2) cm, post: 5.0 (0.2) cm; p < 0.001] and electromyography amplitude [first 3 reps: 55 (5) %MVC; last 3 reps: 87 (10) %MVC], there were no differences between conditions. Both protocols produced decreases in post-exercise strength (pre: 70 Nm, post: 51 Nm; p < 0.001) with no difference between conditions. The nylon protocol resulted in more repetitions during sets 2 [13 (2) vs. 9 (4); p = 0.001] and 3 [10 (2) vs. 7 (4); p = 0.05], while producing lower levels of discomfort following each set (average 3 vs. 4; p < 0.05). In conclusion, both protocols produced similar acute responses thought to be important for promoting muscle growth. However, the use of arbitrary pressures may place some individuals under complete arterial occlusion which may increase the potential risk of an adverse event

Prompt Decays of General Neutralino NLSPs at the Tevatron

Recent theoretical developments have shown that gauge mediation has a much larger parameter space of possible spectra and mixings than previously considered. Motivated by this, we explore the collider phenomenology of gauge mediation models where a general neutralino is the lightest MSSM superpartner (the NLSP), focusing on the potential reach from existing and future Tevatron searches. Promptly decaying general neutralino NLSPs can give rise to final states involving missing energy plus photons, Zs, Ws and/or Higgses. We survey the final states and determine those where the Tevatron should have the most sensitivity. We then estimate the reach of existing Tevatron searches in these final states and discuss new searches (or optimizations of existing ones) that should improve the reach. Finally we comment on the potential for discovery at the LHC.Comment: 41 pages, minor changes, added refs and discussion of previous literatur

Exploring novel correlations in trilepton channels at the LHC for the minimal supersymmetric inverse seesaw model

We investigate signatures of the minimal supersymmetric inverse seesaw model at the large hadron collider (LHC) with three isolated leptons and large missing energy (3\ell + \mET or 2\ell + 1\tau + \mET, with \ell=e,\mu) in the final state. This signal has its origin in the decay of chargino-neutralino (\chpm1\ntrl2) pair, produced in pp collisions. The two body decays of the lighter chargino into a charged lepton and a singlet sneutrino has a characteristic decay pattern which is correlated with the observed large atmospheric neutrino mixing angle. This correlation is potentially observable at the LHC by looking at the ratios of cross sections of the trilepton + \mET channels in certain flavour specific modes. We show that even after considering possible leading standard model backgrounds these final states can lead to reasonable discovery significance at the LHC with both 7 TeV and 14 TeV center-of-mass energy.Comment: 28 pages, 9 .eps figures. 3 new figures and discussions on LHC observables added, minor modifications in text and in the abstract, 23 new references added, matches with the published version in JHE

The Type III Secreted Protein BspR Regulates the Virulence Genes in Bordetella bronchiseptica

Bordetella bronchiseptica is closely related with B. pertussis and B. parapertussis, the causative agents of whooping cough. These pathogenic species share a number of virulence genes, including the gene locus for the type III secretion system (T3SS) that delivers effector proteins. To identify unknown type III effectors in Bordetella, secreted proteins in the bacterial culture supernatants of wild-type B. bronchiseptica and an isogenic T3SS-deficient mutant were compared with iTRAQ-based, quantitative proteomic analysis method. BB1639, annotated as a hypothetical protein, was identified as a novel type III secreted protein and was designated BspR (Bordetella secreted protein regulator). The virulence of a BspR mutant (ΔbspR) in B. bronchiseptica was significantly attenuated in a mouse infection model. BspR was also highly conserved in B. pertussis and B. parapertussis, suggesting that BspR is an essential virulence factor in these three Bordetella species. Interestingly, the BspR-deficient strain showed hyper-secretion of T3SS-related proteins. Furthermore, T3SS-dependent host cell cytotoxicity and hemolytic activity were also enhanced in the absence of BspR. By contrast, the expression of filamentous hemagglutinin, pertactin, and adenylate cyclase toxin was completely abolished in the BspR-deficient strain. Finally, we demonstrated that BspR is involved in the iron-responsive regulation of T3SS. Thus, Bordetella virulence factors are coordinately but inversely controlled by BspR, which functions as a regulator in response to iron starvation

Mutually beneficial host exploitation and ultra-biased sex ratios in quasisocial parasitoids

Selfish interests usually preclude resource sharing, but under some conditions collective actions enhance per capita gains. Such Allee effects underlay early explanations of social evolution but current understanding focusses on kin selection (inclusive fitness). We find an Allee effect that explains unusual quasisociality (cooperative brood care) among parasitoid wasps without invoking or precluding kin selection effects. In Sclerodermus harmandi, individual females produce most offspring when exploiting small hosts alone. However, larger hosts are more successfully exploited by larger groups of females, with the per-female benefits outweighing the costs of host sharing. Further, the extremely biased sex ratios (97% female) are better explained by mutually beneficial female–female interactions that increase the reproductive value of daughters (local resource enhancement), rather than by the usually invoked local mate competition between males. Thus, atypical quasisocial behaviour in a parasitoid wasp directly enhances reproductive success and selects for very extremely female-biased sex ratios

Non-uniform recovery of left ventricular transmural mechanics in ST-segment elevation myocardial infarction

<p>Abstract</p> <p>Background</p> <p>After a transient ischemic episode, the subendocardial region is more severely injured than outer subepicardial layers and may regain a proportionately greater degree of mechanical function in the longitudinal direction. We sought to explore left ventricular (LV) transmural mechanics in patients with ST-segment elevation myocardial infarction (STEMI) for determining the mechanism underlying recovery of global LV function after primary percutaneous coronary intervention (PCI).</p> <p>Methods</p> <p>A total of 42 patients (62 ± 11 years old, 71% male) with a first STEMI underwent serial assessments of LV longitudinal, circumferential and radial strains (LS, CS and RS) by selective tracking of subendocardial and subepicardial regions within 48 hours and a median of 5 months after PCI. LV mechanical parameters were compared with sixteen age and gender matched normal controls.</p> <p>Results</p> <p>In comparison with controls, endocardial and epicardial LS were markedly attenuated at 48 hours following PCI (P < 0.001). An improvement in LV ejection fraction (EF > 5%) following PCI was seen in 24 (57%) patients and was associated with improvement in endocardial and epicardial LS (P < 0.001 and P = 0.003, respectively) and endocardial CS (P = 0.01). Radial strain and wall motion score index, however, remained persistently abnormal. The change in endocardial LS (OR 1.2, 95% CI 1.03 to 1.42, P = 0.01) and the change in epicardial LS (OR 1.2, 95% 1.03 to 1.46, P = 0.02) were significantly associated with the improvement in LVEF, independent of the location of STEMI and the presence of underlying multivessel disease.</p> <p>Conclusions</p> <p>In patients with STEMI treated by PCI, the recovery of LV subendocardial shortening strain seen in the longitudinal direction underlies the improvement in LV global function despite persistent abnormalities in radial mechanics and wall motion score index.</p

Search for a Technicolor omega_T Particle in Events with a Photon and a b-quark Jet at CDF

If the Technicolor omega_T particle exists, a likely decay mode is omega_T -> gamma pi_T, followed by pi_T -> bb-bar, yielding the signature gamma bb-bar. We have searched 85 pb^-1 of data collected by the CDF experiment at the Fermilab Tevatron for events with a photon and two jets, where one of the jets must contain a secondary vertex implying the presence of a b quark. We find no excess of events above standard model expectations. We express the result of an exclusion region in the M_omega_T - M_pi_T mass plane.Comment: 14 pages, 2 figures. Available from the CDF server (PS with figs): http://www-cdf.fnal.gov/physics/pub98/cdf4674_omega_t_prl_4.ps FERMILAB-PUB-98/321-

Overexpression of HMGA1 promotes anoikis resistance and constitutive Akt activation in pancreatic adenocarcinoma cells

HMGA1 proteins are architectural transcription factors that are overexpressed by pancreatic adenocarcinomas. Roles of HMGA1 in mediating the malignant phenotype of this cancer are poorly understood. We tested the hypothesis that overexpression of HMGA1 promotes resistance to anoikis (apoptosis induced by anchorage deprivation) in pancreatic cancer cells. HMGA1 cDNA was stably transfected into MiaPaCa2 human pancreatic adenocarcinoma cells (which have low baseline expression levels of HMGA1). Cells were grown in suspension on PolyHEMA-coated plates and their susceptibility to anoikis was assayed using flow cytometry. Overexpression of HMGA1 was associated with marked reductions in susceptibility to anoikis in concert with increases in Akt phosphorylation (Ser473) and in Akt kinase activity and with reductions in caspase 3 activation. Inhibition of phosphoinositidyl-3 (PI3-K)/Akt pathway with either the small molecule inhibitor LY294002 or dominant-negative Akt resulted in reversal of anoikis resistance induced by HMGA1 overexpression. Further, RNA interference-mediated HMGA1 silencing in MiaPaCa2 and BxPC3 (a human pancreatic adenocarcinoma cell line with high baseline levels of HMGA1 expression) cells resulted in significant increases in susceptibility to anoikis. Our findings suggest HMGA1 promotes anoikis resistance through a PI3-K/Akt-dependent mechanism. Given the putative associations between anoikis resistance and metastatic potential, HMGA1 represents a potential therapeutic target in pancreatic adenocarcinoma

Measurement of D-s(+) and D-s(*+) production in B meson decays and from continuum e(+)e(-) annihilation at √s=10.6 GeV

This is the pre-print version of the Article. The official published version can be accessed from the links below. Copyright @ 2002 APSNew measurements of Ds+ and Ds*+ meson production rates from B decays and from qq̅ continuum events near the Υ(4S) resonance are presented. Using 20.8 fb-1 of data on the Υ(4S) resonance and 2.6 fb-1 off-resonance, we find the inclusive branching fractions B(B⃗Ds+X)=(10.93±0.19±0.58±2.73)% and B(B⃗Ds*+X)=(7.9±0.8±0.7±2.0)%, where the first error is statistical, the second is systematic, and the third is due to the Ds+→φπ+ branching fraction uncertainty. The production cross sections σ(e+e-→Ds+X)×B(Ds+→φπ+)=7.55±0.20±0.34pb and σ(e+e-→Ds*±X)×B(Ds+→φπ+)=5.8±0.7±0.5pb are measured at center-of-mass energies about 40 MeV below the Υ(4S) mass. The branching fractions ΣB(B⃗Ds(*)+D(*))=(5.07±0.14±0.30±1.27)% and ΣB(B⃗Ds*+D(*))=(4.1±0.2±0.4±1.0)% are determined from the Ds(*)+ momentum spectra. The mass difference m(Ds+)-m(D+)=98.4±0.1±0.3MeV/c2 is also measured.This work was supported by DOE and NSF (USA), NSERC (Canada), IHEP (China), CEA and CNRS-IN2P3 (France), BMBF (Germany), INFN (Italy), NFR (Norway), MIST (Russia), and PPARC (United Kingdom). Individuals have received support from the Swiss NSF, A. P. Sloan Foundation, Research Corporation, and Alexander von Humboldt Foundation