Shedding light on the ttˉt \bar t asymmetry: the photon handle

We investigate a charge asymmetry in $t \bar t \gamma$ production at the LHC that provides complementary information to the measured asymmetries in $t \bar t$ production. We estimate the experimental uncertainty in its measurement at the LHC with 8 and 14 TeV. For new physics models that simultaneously reproduce the asymmetry excess in $t \bar t$ at the Tevatron and the SM-like asymmetry at the LHC, the measurement in $t \bar t \gamma$ at the LHC could exhibit significant deviations with respect to the SM prediction.Comment: LaTeX 15 page

Spontaneous electro-weak symmetry breaking and cold dark matter

In the standard model, the weak gauge bosons and fermions obtain mass after spontaneous electro-weak symmetry breaking, which is realized through one fundamental scalar field, namely Higgs field. In this paper we study the simplest scalar cold dark matter model in which the scalar cold dark matter also obtains mass through interaction with the weak-doublet Higgs field, the same way as those of weak gauge bosons and fermions. Our study shows that the correct cold dark matter relic abundance within $3\sigma$ uncertainty ($0.093 < \Omega_{dm} h^2 < 0.129$) and experimentally allowed Higgs boson mass ($114.4 \le m_h \le 208$ GeV) constrain the scalar dark matter mass within $48 \le m_S \le 78$ GeV. This result is in excellent agreement with that of W. de Boer et.al. ($50 \sim 100$ GeV). Such kind of dark matter annihilation can account for the observed gamma rays excess ($10\sigma$) at EGRET for energies above 1 GeV in comparison with the expectations from conventional Galactic models. We also investigate other phenomenological consequences of this model. For example, the Higgs boson decays dominantly into scalar cold dark matter if its mass lies within $48 \sim 64$ GeV.Comment: 4 Revtex4 pages, refs adde

Measuring the W-t-b Interaction at the ILC

The large top quark mass suggests that the top plays a pivotal role in Electroweak symmetry-breaking dynamics and, as a result, may have modified couplings to Electroweak bosons. Hadron colliders can provide measurements of these couplings at the ~10% level, and one of the early expected triumphs of the International Linear Collider is to reduce these uncertainties to the per cent level. In this article, we propose the first direct measurement of the Standard Model W-t-b coupling at the ILC, from measurements of t tbar-like signals below the t tbar production threshold. We estimate that the ILC with 100 fb^{-1} can measure a combination of the coupling and top width to high precision, and when combined with a direct measurement of the top width from the above-threshold scan, results in a model-independent measurement of the W-t-b interaction of the order of ~ 3%

The logic of strategic consensus: state environment and civil war

Doctor of PhilosophySecurity StudiesEmizet F. KisanganiWhy are states sometimes unable to avoid the occurrence of civil war? Most existing theories of civil war focus on rebels’ motivation and capabilities, while taking government’s actions as givens. Not only is the government a key player in the process leading up to civil war, but it is also a non-unitary actor composed of individuals and groups with diverging aspirations. Thus, understanding civil war requires an explanation of the conditions that facilitate or impede what governments do to provide political order. To fill this gap, this dissertation proposes a state-centered theory that explains civil war as an indirect function of state environment, defined in terms of structural and institutional conditions under which governments operate. The argument is that state environment determines the scope of leaders’ consensus on accommodation and coercion, two strategies that governments rely on to provide political order. Specifically, harsh socioeconomic conditions reduce leaders’ strategic consensus. Moreover, leaders’ divisions in socioeconomically poor societies is further exacerbated by democratic institutions. In turn, the lack of consensus on accommodation and coercion increases the risks of civil war. Quantitative and qualitative methods are used to test the theory. The quantitative analysis relies on mediation techniques and on a cross-sectional time series of 162 countries from 1960 to 2007. The results support the theoretical argument. Socioeconomic development is indirectly and inversely related to civil war. About two-thirds of its effect is transmitted through accommodation, while one-third occurs through coercion. Moreover, democratic institutions are positively associated with civil war. When socioeconomic development is low, states with open institutions are the least accommodative and the most coercive. The qualitative methods of “structured, focused comparison” and “process tracing” are used to investigate three cases (Côte d’Ivoire, Romania, and Benin). The findings show that the emergence of sociopolitical dissidence often results from changes in the structure of the state’s socioeconomic or political environment. However, the risks of escalation into civil war are highest when leaders lack consensus about a strategy to resolve the issue at stake. In turn, leaders’ disunity about a bargaining strategy is found to be a product of calculations for political survival

Nitric oxide sensing in plants is mediated by proteolytic control of group VII ERF transcription factors

Nitric oxide (NO) is an important signaling compound in prokaryotes and eukaryotes. In plants, NO regulates critical developmental transitions and stress responses. Here, we identify a mechanism for NO sensing that coordinates responses throughout development based on targeted degradation of plant-specific transcriptional regulators, the group VII ethylene response factors (ERFs). We show that the N-end rule pathway of targeted proteolysis targets these proteins for destruction in the presence of NO, and we establish them as critical regulators of diverse NO-regulated processes, including seed germination, stomatal closure, and hypocotyl elongation. Furthermore, we define the molecular mechanism for NO control of germination and crosstalk with abscisic acid (ABA) signaling through ERF-regulated expression of ABSCISIC ACID INSENSITIVE5 (ABI5). Our work demonstrates how NO sensing is integrated across multiple physiological processes by direct modulation of transcription factor stability and identifies group VII ERFs as central hubs for the perception of gaseous signals in plants

Effect of various dietary regimens on oral challenge with Mycobacterium avium subsp. paratuberculosis in a rabbit model

Rabbits are susceptible to infection by Mycobacterium avium subspecies paratuberculosis (MAP) in both wildlife and experimental conditions. Under the hypotheses that nutrient balance might influence the establishment of infection, we designed an experiment where MAP intestinal colonization was assessed under three dietary regimens: high fiber, high protein, and regular diet in New Zealand white rabbits submitted to oral challenge with MAP.Lowest weight gain (F=5.17, p=0.024), higher tissue culture positivity rates (X2=7.43, p=0.024) and especially extended MAP-compatible lesions (F=5.78, p=0.017) were detected in the regular diet.Taken altogether, results indicate that paratuberculosis infection was achieved affecting mostly regular diet animals and showing that dietary changes may modulate the course of the infection

Plasmonic/magnetic nanocomposites: Gold nanorods-functionalized silica coated magnetic nanoparticles

: We report here on the fabrication of a new example of nano-object that combines magnetic and plasmonic properties. The strategy is based on the electrostatic assembly of negatively charged gold nanorods (NIR-resonant) on positively charged silica-coated iron oxide nanoparticles. Silica coating of magnetic nanoparticles prevented iron oxide nanoparticles irreversible aggregation in water environment. Finally the stability of the nanocomposite in biological medium has been improved through a protein coating (BSA, bovine serum albumin). Morphological, optical and magnetic properties of the hybrid nanomaterials have been evaluated as well as its ability to be manipulated by an external magnetic field. Furthermore, temperature characterization upon NIR laser excitation has been performed in order to assess nanocomposite capability of increasing local environmental temperature. This nanomaterial could be used as a smart tool for photothermal treatment of cancerous lesions in order to maximize precision and efficacy of tissue heating upon laser stimulation by magnetically accumulating nanoparticles nearby the cancerous lesion, avoiding dispersion of the nanomaterial

Confined cell migration and asymmetric hydraulic environments to evaluate the metastatic potential of cancer cells

Metastasis, a hallmark of cancer development, is also the leading reason for most cancer-related deaths. Furthermore, cancer cells are highly adaptable to microenvironments and can migrate along pre-existing channel-like tracks of anatomical structures. However, more representative three-dimensional models are required to reproduce the heterogeneity of metastatic cell migration in vivo to further understand the metastasis mechanism and develop novel therapeutic strategies against it. Here, we designed and fabricated different microfluidic-based devices that recreate confined migration and diverse environments with asymmetric hydraulic resistances. Our results show different migratory potential between metastatic and nonmetastatic cancer cells in confined environments. Moreover, although nonmetastatic cells have not been tested against barotaxis due to their low migration capacity, metastatic cells present an enhanced preference to migrate through the lowest resistance path, being sensitive to barotaxis. This device, approaching the study of metastasis capability based on confined cell migration and barotactic cell decisions, may pave the way for the implementation of such technology to determine and screen the metastatic potential of certain cancer cells

Detection of rhabdovirus viral RNA in oropharyngeal swabs and ectoparasites of spanish bats

Rhabdoviruses infect a variety of hosts, including mammals, birds, reptiles, fish, insects and plants. As bats are the natural host for most members of the genus Lyssavirus, the specificity of the amplification methods used for active surveillance is usually restricted to lyssaviruses. However, the presence of other rhabdoviruses in bats has also been reported. In order to broaden the scope of such methods, a new RT-PCR, able to detect a diverse range of rhabdoviruses, was designed. The method detected 81 of 86 different rhabdoviruses. In total, 1488 oropharyngeal bat swabs and 38 nycteribiid samples were analysed, and 17 unique rhabdovirus-related sequences were detected. Phylogenetic analysis suggested that those sequences detected in bats did not constitute a monophyletic group, even when originating from the same bat species. However, all of the sequences detected in nycteribiids and one sequence obtained from a bat did constitute a monophyletic group with Drosophila melanogaster sigma rhabdovirus. © 2013 Crown.Peer Reviewe

Immune response profiles of calves following vaccination with live BCG and inactivated Mycobacterium bovis vaccine candidates

<div><p>Conventional control and eradication strategies for bovine tuberculosis (BTB) face tremendous difficulties in developing countries; countries with wildlife reservoirs, a complex wildlife-livestock-human interface or a lack of veterinary and veterinary public health surveillance. Vaccination of cattle and other species might in some cases provide the only suitable control strategy for BTB, while in others it may supplement existing test-and-slaughter schemes. However, the use of live BCG has several limitations and the global rise of HIV/AIDS infections has furthermore warranted the exploration of inactivated vaccine preparations. The aim of this study was to compare the immune response profiles in response to parenteral vaccination with live BCG and two inactivated vaccine candidates in cattle.</p><p>Twenty-four mixed breed calves (<i>Bos taurus</i>) aged 4–6 months, were allocated to one of four groups and vaccinated sub-cutaneously with live <i>M</i>. <i>bovis</i> BCG (Danish 1331), formalin-inactivated <i>M</i>. <i>bovis</i> BCG, heat-killed <i>M</i>. <i>bovis</i> or PBS/Montanide™ (control). Interferon-γ responsiveness and antibody production were measured prior to vaccination and at weekly intervals thereafter for twelve weeks. At nine weeks post-priming, animals were skin tested using tuberculins and MTBC specific protein cocktails and subsequently challenged through intranodular injection of live <i>M</i>. <i>bovis</i> BCG.</p><p>The animals in the heat-killed <i>M</i>. <i>bovis</i> group demonstrated strong and sustained cell-mediated and humoral immune responses, significantly higher than the control group in response to vaccination, which may indicate a protective immune profile. Animals in this group showed reactivity to the skin test reagents, confirming good vaccine take. Lastly, although not statistically significant, recovery of BCG after challenge was lowest in the heat-killed <i>M</i>. <i>bovis</i> group.</p><p>In conclusion, the parenteral heat-killed <i>M</i>. <i>bovis</i> vaccine proved to be clearly immunogenic in cattle in the present study, urging further evaluation of the vaccine in challenge studies using virulent <i>M</i>. <i>bovis</i> and assessment of vaccine efficacy in field conditions.</p></div