2,375 research outputs found
Avian Resistance to Campylobacter jejuni Colonization Is Associated with an Intestinal Immunogene Expression Signature Identified by mRNA Sequencing
peer-reviewedThis research was funded by the The Irish Department of Agriculture and Food’s Food Institutional Research Measure (http://www.agriculture.gov.ie/
research/foodinstitutionalresearchmeasurefirm) – Grant No: 06_RDD_486.Campylobacter jejuni is the most common cause of human bacterial gastroenteritis and is associated with several post-infectious manifestations, including onset of the autoimmune neuropathy Guillain-Barré syndrome, causing significant morbidity and mortality. Poorly-cooked chicken meat is the most frequent source of infection as C. jejuni colonizes the avian intestine in a commensal relationship. However, not all chickens are equally colonized and resistance seems to be genetically determined. We hypothesize that differences in immune response may contribute to variation in colonization levels between susceptible and resistant birds. Using high-throughput sequencing in an avian infection model, we investigate gene expression associated with resistance or susceptibility to colonization of the gastrointestinal tract with C. jejuni and find that gut related immune mechanisms are critical for regulating colonization. Amongst a single population of 300 4-week old chickens, there was clear segregation in levels of C. jejuni colonization 48 hours post-exposure. RNAseq analysis of caecal tissue from 14 C. jejuni-susceptible and 14 C. jejuni-resistant birds generated over 363 million short mRNA sequences which were investigated to identify 219 differentially expressed genes. Significantly higher expression of genes involved in the innate immune response, cytokine signaling, B cell and T cell activation and immunoglobulin production, as well as the renin-angiotensin system was observed in resistant birds, suggesting an early active immune response to C. jejuni. Lower expression of these genes in colonized birds suggests suppression or inhibition of a clearing immune response thus facilitating commensal colonization and generating vectors for zoonotic transmission. This study describes biological processes regulating C. jejuni colonization of the avian intestine and gives insight into the differential immune mechanisms incited in response to commensal bacteria in general within vertebrate populations. The results reported here illustrate how an exaggerated immune response may be elicited in a subset of the population, which alters host-microbe interactions and inhibits the commensal state, therefore having wider relevance with regard to inflammatory and autoimmune disease
General Neutralino NLSPs at the Early LHC
Gauge mediated supersymmetry breaking (GMSB) is a theoretically
well-motivated framework with rich and varied collider phenomenology. In this
paper, we study the Tevatron limits and LHC discovery potential for a wide
class of GMSB scenarios in which the next-to-lightest superpartner (NLSP) is a
promptly-decaying neutralino. These scenarios give rise to signatures involving
hard photons, 's, 's, jets and/or higgses, plus missing energy. In order
to characterize these signatures, we define a small number of minimal spectra,
in the context of General Gauge Mediation, which are parameterized by the mass
of the NLSP and the gluino. Using these minimal spectra, we determine the most
promising discovery channels for general neutralino NLSPs. We find that the
2010 dataset can already cover new ground with strong production for all NLSP
types. With the upcoming 2011-2012 dataset, we find that the LHC will also have
sensitivity to direct electroweak production of neutralino NLSPs.Comment: 26 page
Light Stop NLSPs at the Tevatron and LHC
How light can the stop be given current experimental constraints? Can it
still be lighter than the top? In this paper, we study this and related
questions in the context of gauge-mediated supersymmetry breaking, where a stop
NLSP decays into a W, b and gravitino. Focusing on the case of prompt decays,
we simulate several existing Tevatron and LHC analyses that would be sensitive
to this scenario, and find that they allow the stop to be as light as 150 GeV,
mostly due to the large top production background. With more data, the existing
LHC analyses will be able to push the limit up to at least 180 GeV. We hope
this work will motivate more dedicated experimental searches for this simple
scenario, in which, for most purposes, the only free parameters are the stop
mass and lifetime.Comment: 31 pages, 11 figures; v2: added minor clarifications and reference
Social determinants of content selection in the age of (mis)information
Despite the enthusiastic rhetoric about the so called \emph{collective
intelligence}, conspiracy theories -- e.g. global warming induced by chemtrails
or the link between vaccines and autism -- find on the Web a natural medium for
their dissemination. Users preferentially consume information according to
their system of beliefs and the strife within users of opposite narratives may
result in heated debates. In this work we provide a genuine example of
information consumption from a sample of 1.2 million of Facebook Italian users.
We show by means of a thorough quantitative analysis that information
supporting different worldviews -- i.e. scientific and conspiracist news -- are
consumed in a comparable way by their respective users. Moreover, we measure
the effect of the exposure to 4709 evidently false information (satirical
version of conspiracy theses) and to 4502 debunking memes (information aiming
at contrasting unsubstantiated rumors) of the most polarized users of
conspiracy claims. We find that either contrasting or teasing consumers of
conspiracy narratives increases their probability to interact again with
unsubstantiated rumors.Comment: misinformation, collective narratives, crowd dynamics, information
spreadin
The FUSE survey of OVI absorption in and near the Galaxy
We present FUSE observations of OVI absorption in a sample of 100
extragalactic targets and 2 distant halo stars. We describe the details of the
calibration, alignment in velocity, continuum fitting, and manner in which
contaminants were removed (Galactic H2, absorption intrinsic to the background
target and intergalactic Ly-beta lines). We searched for OVI absorption in the
velocity range -1200 to 1200 km/s. With a few exceptions, we only find OVI
between -400 and 400 km/s; the exceptions may be intergalactic OVI. We discuss
the separation of the observed OVI absorption into components associated with
the Galactic halo and components at high-velocity, which are probably located
in the neighborhood of the Galaxy. We describe the measurements of equivalent
width and column density, and we analyze the different contributions to the
errors. We conclude that low-velocity Galactic OVI absorption occurs along all
sightlines - the few non-detections only occur in noisy spectra. We further
show that high-velocity OVI is very common, having equivalent width >65 mAA in
50% of the sightlines and >30 mAA in 70% of the high-quality sightlines. The
high-velocity OVI absorption has velocities relative to the LSR of
+/-(100--330) km/s; there is no correlation between velocity and absorption
strength. We present 50 km/s wide OVI channel maps. These show evidence for the
imprint of Galactic rotation. They also highlight two known HI high-velocity
clouds (complex~C and the Magellanic Stream). The channel maps further show
that OVI at velocities <-200 km/s occurs along all sightlines in the region
l=20-150, b200 km/s occurs along all sightlines
in the region l=180-300, b>20 (abbreviated).Comment: 85 pages, 127 figures, 13 color figures, 3 tables, AASTeX preprint
format. All figures are in PNG format due to space concerns. Bound copies of
manuscript and two accompanying articles are available upon request.
submitted to ApJ
The Status of GMSB After 1/fb at the LHC
We thoroughly investigate the current status of supersymmetry in light of the
latest searches at the LHC, using General Gauge Mediation (GGM) as a
well-motivated signature generator that leads to many different simplified
models. We consider all possible promptly-decaying NLSPs in GGM, and by
carefully reinterpreting the existing LHC searches, we derive limits on both
colored and electroweak SUSY production. Overall, the coverage of GGM parameter
space is quite good, but much discovery potential still remains even at 7 TeV.
We identify several regions of parameter space where the current searches are
the weakest, typically in models with electroweak production, third generation
sfermions or squeezed spectra, and we suggest how ATLAS and CMS might modify
their search strategies given the understanding of GMSB at 1/fb. In particular,
we propose the use of leptonic to suppress backgrounds.
Because we express our results in terms of simplified models, they have broader
applicability beyond the GGM framework, and give a global view of the current
LHC reach. Our results on 3rd generation squark NLSPs in particular can be
viewed as setting direct limits on naturalness.Comment: 44 pages, refs added, typos fixed, improved MC statistics in fig 1
Methods and systems for advanced spaceport information management
Advanced spaceport information management methods and systems are disclosed. In one embodiment, a method includes coupling a test system to the payload and transmitting one or more test signals that emulate an anticipated condition from the test system to the payload. One or more responsive signals are received from the payload into the test system and are analyzed to determine whether one or more of the responsive signals comprises an anomalous signal. At least one of the steps of transmitting, receiving, analyzing and determining includes transmitting at least one of the test signals and the responsive signals via a communications link from a payload processing facility to a remotely located facility. In one particular embodiment, the communications link is an Internet link from a payload processing facility to a remotely located facility (e.g. a launch facility, university, etc.)
Small steps towards Grand Unification and the electron/positron excesses in cosmic-ray experiments
We consider a small extension of the standard model by adding two Majorana
fermions; those are adjoint representations of the SU(2)_L and SU(3)_c gauge
groups of the standard model. In this extension, the gauge coupling unification
at an energy scale higher than 10^{15} GeV is realized when the masses of the
triplet and the octet fermions are smaller than 10^4 GeV and 10^{12} GeV,
respectively. We also show that an appropriate symmetry ensures a long lifetime
of the neutral component of the triplet fermion whose thermal relic density
naturally explains the observed dark matter density. The electron/positron
excesses observed in recent cosmic-ray experiments can be also explained by the
decay of the triplet fermion.Comment: 11 pages, 5 figure
Viability of MSSM scenarios at very large tan(beta)
We investigate the MSSM with very large tan(beta) > 50, where the fermion
masses are strongly affected by loop-induced couplings to the "wrong" Higgs,
imposing perturbative Yukawa couplings and constraints from flavour physics.
Performing a low-energy scan of the MSSM with flavour-blind soft terms, we find
that the branching ratio of B->tau nu and the anomalous magnetic moment of the
muon are the strongest constraints at very large tan(beta) and identify the
viable regions in parameter space. Furthermore we determine the scale at which
the perturbativity of the Yukawa sector breaks down, depending on the
low-energy MSSM parameters. Next, we analyse the very large tan(beta) regime of
General Gauge Mediation (GGM) with a low mediation scale. We investigate the
requirements on the parameter space and discuss the implied flavour
phenomenology. We point out that the possibility of a vanishing Bmu term at a
mediation scale M = 100 TeV is challenged by the experimental data on B->tau nu
and the anomalous magnetic moment of the muon.Comment: 29 pages, 7 figures. v2: discussion in sections 1 and 4 expanded,
conclusions unchanged. Matches version published in JHE
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