205 research outputs found
Signatures of clumpy dark matter in the global 21 cm background signal
We examine the extent to which the self-annihilation of supersymmetric
neutralino dark matter, as well as light dark matter, influences the rate of
heating, ionisation and Lyman-alpha pumping of interstellar hydrogen and helium
and the extent to which this is manifested in the 21cm global background
signal. We fully consider the enhancements to the annihilation rate from DM
halos and substructures within them. We find that the influence of such
structures can result in significant changes in the differential brightness
temperature. The changes at redsfhits z<25 are likely to be undetectable due to
the presence of the astrophysical signal; however, in the most favourable
cases, deviations in the differential brightness temperature, relative to its
value in the absence of self-annihilating DM, of up to ~20 mK at z=30 can
occur. Thus we conclude that, in order to exclude these models, experiments
measuring the global 21cm signal, such as EDGES and CORE, will need to reduce
the systematics at 50 MHz to below 20 mK.Comment: V3: 32 pages, 14 figures, 4 tables. Replaced to match version
accepted for publication in PRD. Major revisions to address referee's
comment
Difficulties for Compact Composite Object Dark Matter
It has been suggested ``that DM particles are strongly interacting composite
macroscopically large objects ... made of well known light quarks (or ...
antiquarks)." In doing so it is argued that these compact composite objects
(CCOs) are ``natural explanations of many observed data, such as [the] 511 keV
line from the bulge of our galaxy" observed by INTEGRAL and the excess of
diffuse gamma-rays in the 1-20 MeV band observed by COMPTEL. Here we argue that
the atmospheres of positrons that surround CCOs composed of di-antiquark pairs
in the favoured Colour-Flavour-Locked superconducting state are sufficiently
dense as to stringently limit the penetration of interstellar electrons
incident upon them, resulting in an extreme suppression of previously estimated
rates of positronium, and hence the flux of 511 keV photons resulting from
their decays, and also in the rate of direct electron-positron annihilations,
which yield the MeV photons proposed to explain the 1-20 MeV excess. We also
demonstrate that even if a fraction of positrons somehow penetrated to the
surface of the CCOs, the extremely strong electric fields generated from the
bulk antiquark matter would result in the destruction of positronium atoms long
before they decay.Comment: 7 Pages, 4 Figures. Major changes invoke
Light neutralino in the MSSM: An update with the latest LHC results
We discuss the scenario of light neutralino dark matter in the minimal
supersymmetric standard model, which is motivated by the results of some of the
direct detection experiments --- DAMA, CoGENT, and CRESST. We update our
previous analysis with the latest results of the LHC. We show that new LHC
constraints disfavour the parameter region that can reproduce the results of
DAMA and CoGENT.Comment: 4 pages, 4 figures, to appear in the conference proceedings of TAUP
2011, Munich Germany, 5-9 September 201
A multi-centre cohort study evaluating the role of Inflammatory Markers In patient’s presenting with acute ureteric Colic (MIMIC)
BACKGROUND:
Spontaneous Stone Passage (SSP) rates in acute ureteric colic range from 47–75%. There is conflicting evidence on the role of raised inflammatory markers in acute ureteric colic. The use of an easily applicable biomarker that could predict SSP or need for intervention would improve the management of obstructing ureteric stones. Thus, there is a need to determine in an appropriately powered study, in patients who are initially managed conservatively, which factors at the time of acute admission can predict subsequent patient outcome such as SSP and the need for intervention. Particularly, establishing whether levels of white cell count (WBC) at presentation are associated with likelihood of SSP or intervention may guide clinicians on the management of these patients’ stones.
DESIGN:
Multi-center cohort study disseminated via the UK British Urology Researchers in Surgical Training (BURST) and Australian Young Urology Researchers Organisation (YURO).
PRIMARY RESEARCH QUESTION:
What is the association between WBC and SSP in patients discharged from emergency department after initial conservative management?
PATIENT POPULATION:
Patients who have presented with acute renal colic with CT KUB evidence of a solitary ureteric stone. A minimum sample size of 720 patients across 15 centres will be needed.
HYPOTHESIS:
A raised WBC is associated with decreased odds of spontaneous stone passage.
PRIMARY OUTCOME:
The occurrence of SSP within six months of presentation with acute ureteric colic (YES/NO). SSP was defined as absence of need for intervention to assist stone passage
STATISTICAL ANALYSIS PLAN:
A multivariable logistic regression model will be constructed, where the outcome of interest is SSP using data from patients who do not undergo intervention at presentation. A random effect will be used to account for clustering of patients within hospitals/institutions. The model will include adjustments for gender, age as control variables
Cosmic Ray Anomalies from the MSSM?
The recent positron excess in cosmic rays (CR) observed by the PAMELA
satellite may be a signal for dark matter (DM) annihilation. When these
measurements are combined with those from FERMI on the total () flux
and from PAMELA itself on the ratio, these and other results are
difficult to reconcile with traditional models of DM, including the
conventional mSUGRA version of Supersymmetry even if boosts as large as
are allowed. In this paper, we combine the results of a previously
obtained scan over a more general 19-parameter subspace of the MSSM with a
corresponding scan over astrophysical parameters that describe the propagation
of CR. We then ascertain whether or not a good fit to this CR data can be
obtained with relatively small boost factors while simultaneously satisfying
the additional constraints arising from gamma ray data. We find that a specific
subclass of MSSM models where the LSP is mostly pure bino and annihilates
almost exclusively into pairs comes very close to satisfying these
requirements. The lightest in this set of models is found to be
relatively close in mass to the LSP and is in some cases the nLSP. These models
lead to a significant improvement in the overall fit to the data by an amount
dof in comparison to the best fit without Supersymmetry
while employing boosts . The implications of these models for future
experiments are discussed.Comment: 57 pages, 31 figures, references adde
Closing in on Asymmetric Dark Matter I: Model independent limits for interactions with quarks
It is argued that experimental constraints on theories of asymmetric dark
matter (ADM) almost certainly require that the DM be part of a richer hidden
sector of interacting states of comparable mass or lighter. A general requisite
of models of ADM is that the vast majority of the symmetric component of the DM
number density must be removed in order to explain the observed relationship
via the DM asymmetry. Demanding the efficient
annihilation of the symmetric component leads to a tension with experimental
limits if the annihilation is directly to Standard Model (SM) degrees of
freedom. A comprehensive effective operator analysis of the model independent
constraints on ADM from direct detection experiments and LHC monojet searches
is presented. Notably, the limits obtained essentially exclude models of ADM
with mass 1GeV 100GeV annihilating to SM quarks via
heavy mediator states. This motivates the study of portal interactions between
the dark and SM sectors mediated by light states. Resonances and threshold
effects involving the new light states are shown to be important for
determining the exclusion limits.Comment: 18+6 pages, 18 figures. v2: version accepted for publicatio
Making sense of violence: a study of narrative meaning
Dramatized violence has been a feature of entertainment in western civilization throughout history. The function of film violence is explored and compared to violence encountered in real life. The role of narrative in individuals' meaning-making processes is also investigated. Six adults were individually interviewed using a semi-structured schedule and narrative analysis was implemented. The findings revealed that real life violence is experientially distinct from film violence but narrative was found to be central to participants' quest for the meaning of violence in both contexts. The narrative framework of violence and whether it is justifiable were fundamental to participants' understanding. The function of violent film was found to be multifaceted: it can teach viewers about the consequences of violence; it allows them to speculate about their own and others' reactions to violence; and it provides an opportunity to experience something which is ordinarily outside of our experience in order to satisfy our human existential needs
Integrated analyses of copy number variations and gene differential expression in lung squamous-cell carcinoma
Probing new physics with long-lived charged particles produced by atmospheric and astrophysical neutrinos
As suggested by some extensions of the Standard Model of particle physics,
dark matter may be a super-weakly interacting lightest stable particle, while
the next-to-lightest particle (NLP) is charged and meta-stable. One could test
such a possibility with neutrino telescopes, by detecting the charged NLPs
produced in high-energy neutrino collisions with Earth matter. We study the
production of charged NLPs by both atmospheric and astrophysical neutrinos;
only the latter, which is largely uncertain and has not been detected yet, was
the focus of previous studies. We compute the resulting fluxes of the charged
NLPs, compare those of different origins, and analyze the dependence on the
underlying particle physics setup. We point out that even if the astrophysical
neutrino flux is very small, atmospheric neutrinos, especially those from the
prompt decay of charmed mesons, may provide a detectable flux of NLP pairs at
neutrino telescopes such as IceCube. We also comment on the flux of charged
NLPs expected from proton-nucleon collisions, and show that, for theoretically
motivated and phenomenologically viable models, it is typically sub-dominant
and below detectable rates.Comment: 27 pages, 6 figures; accepted for publication in JCA
Dark Matter Searches: The Nightmare Scenario
The unfortunate case where the Large Hadron Collider (LHC) fails to discover
physics Beyond the Standard Model (BSM) is sometimes referred to as the
"Nightmare scenario" of particle physics. We study the consequences of this
hypothetical scenario for Dark Matter (DM), in the framework of the constrained
Minimal Supersymmetric Standard Model (cMSSM). We evaluate the surviving
regions of the cMSSM parameter space after null searches at the LHC, using
several different LHC configurations, and study the consequences for DM
searches with ton-scale direct detectors and the IceCube neutrino telescope. We
demonstrate that ton-scale direct detection experiments will be able to
conclusively probe the cMSSM parameter space that would survive null searches
at the LHC with 100fb of integrated luminosity at 14TeV. We also
demonstrate that IceCube (80 strings plus DeepCore) will be able to probe as
much as 17% of the currently favoured parameter space after 5 years of
observation.Comment: V2: 24 pages, 6 figures, 4 tables. Replaced to match version
published in JCAP. Minor revisions made to address referee's comment
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