52 research outputs found
The neutrino signal at HALO: learning about the primary supernova neutrino fluxes and neutrino properties
Core-collapse supernova neutrinos undergo a variety of phenomena when they
travel from the high neutrino density region and large matter densities to the
Earth. We perform analytical calculations of the supernova neutrino fluxes
including collective effects due to the neutrino-neutrino interactions, the
Mikheev-Smirnov-Wolfenstein (MSW) effect due to the neutrino interactions with
the background matter and decoherence of the wave packets as they propagate in
space. We predict the numbers of one- and two-neutron charged and
neutral-current electron-neutrino scattering on lead events. We show that, due
to the energy thresholds, the ratios of one- to two-neutron events are
sensitive to the pinching parameters of neutrino fluxes at the neutrinosphere,
almost independently of the presently unknown neutrino properties. Besides,
such events have an interesting sensitivity to the spectral split features that
depend upon the presence/absence of energy equipartition among neutrino
flavors. Our calculations show that a lead-based observatory like the Helium
And Lead Observatory (HALO) has the potential to pin down important
characteristics of the neutrino fluxes at the neutrinosphere, and provide us
with information on the neutrino transport in the supernova core.Comment: 30 pages, 12 figures, 6 tables, minor correction
Neutrino Probes of the Nature of Light Dark Matter
Dark matter particles gravitationally trapped inside the Sun may annihilate
into Standard Model particles, producing a flux of neutrinos. The prospects of
detecting these neutrinos in future multi-\kton{} neutrino detectors designed
for other physics searches are explored here. We study the capabilities of a
34/100 \kton{} liquid argon detector and a 100 \kton{} magnetized iron
calorimeter detector. These detectors are expected to determine the energy and
the direction of the incoming neutrino with unprecedented precision allowing
for tests of the dark matter nature at very low dark matter masses, in the
range of 5-50 GeV. By suppressing the atmospheric background with angular cuts,
these techniques would be sensitive to dark matter - nucleon spin dependent
cross sections at the fb level, reaching down to a few ab for the most
favorable annihilation channels and detector technology.Comment: Minor changes and clarifications, matches JCAP versio
Enhanced Sensitivity to Dark Matter Self-annihilations in the Sun using Neutrino Spectral Information
Self-annihilating dark matter gravitationally captured by the Sun could yield
observable neutrino signals at current and next generation neutrino detectors.
By exploiting such signals, neutrino detectors can probe the spin-dependent
scattering of weakly interacting massive particles (WIMPs) with nucleons in the
Sun. We describe a method how to convert constraints on neutrino fluxes to a
limit on the WIMP-nucleon scattering cross section. In this method all neutrino
flavors can be treated in a very similar way. We study the sensitivity of
neutrino telescopes for Solar WIMP signals using vertex contained events and
find that this detection channel is of particular importance in the search for
low mass WIMPs. We obtain highly competitive sensitivities with all neutrino
flavor channels for a Megaton sized detector through the application of basic
spectral selection criteria. Best results are obtained with the electron
neutrino channel. We discuss associated uncertainties and provide a procedure
how to treat them for analyses in a consistent way.Comment: 21 pages, 6 figure
First Study of Combined Blazar Light Curves with FACT and HAWC
For studying variable sources like blazars, it is crucial to achieve unbiased
monitoring, either with dedicated telescopes in pointing mode or survey
instruments. At TeV energies, the High Altitude Water Cherenkov (HAWC)
observatory monitors approximately two thirds of the sky every day. It uses the
water Cherenkov technique, which provides an excellent duty cycle independent
of weather and season. The First G-APD Cherenkov Telescope (FACT) monitors a
small sample of sources with better sensitivity, using the imaging air
Cherenkov technique. Thanks to its camera with silicon-based photosensors, FACT
features an excellent detector performance and stability and extends its
observations to times with strong moonlight, increasing the duty cycle compared
to other imaging air Cherenkov telescopes. As FACT and HAWC have overlapping
energy ranges, a joint study can exploit the longer daily coverage given that
the observatories' locations are offset by 5.3 hours. Furthermore, the better
sensitivity of FACT adds a finer resolution of features on hour-long time
scales, while the continuous duty cycle of HAWC ensures evenly sampled
long-term coverage. Thus, the two instruments complement each other to provide
a more complete picture of blazar variability. In this presentation, the first
joint study of light curves from the two instruments will be shown, correlating
long-term measurements with daily sampling between air and water Cherenkov
telescopes. The presented results focus on the study of the variability of the
bright blazars Mrk 421 and Mrk 501 during the last two years featuring various
flaring activities.Comment: 6 pages, 2 figures. Contribution to the 6th International Symposium
on High Energy Gamma-Ray Astronomy (Gamma2016), Heidelberg, Germany. To be
published in the AIP Conference Proceeding
Protocol for a cluster randomised waitlist-controlled trial of a goal-based behaviour change intervention for employees in workplaces enrolled in health and wellbeing initiatives.
Many workplaces offer health and wellbeing initiatives to their staff as recommended by international and national health organisations. Despite their potential, the influence of these initiatives on health behaviour appears limited and evaluations of their effectiveness are rare. In this research, we propose evaluating the effectiveness of an established behaviour change intervention in a new workplace context. The intervention, 'mental contrasting plus implementation intentions', supports staff in achieving their health and wellbeing goals by encouraging them to compare the future with the present and to develop a plan for overcoming anticipated obstacles. We conducted a systematic review that identified only three trials of this intervention in workplaces and all of them were conducted within healthcare organisations. Our research will be the first to evaluate the effectiveness of mental contrasting outside a solely healthcare context. We propose including staff from 60 organisations, 30 in the intervention and 30 in a waitlisted control group. The findings will contribute to a better understanding of how to empower and support staff to improve their health and wellbeing. Trial registration: ISRCTN17828539
Static platelet adhesion, flow cytometry and serum TXB2 levels for monitoring platelet inhibiting treatment with ASA and clopidogrel in coronary artery disease: a randomised cross-over study
<p>Abstract</p> <p>Background</p> <p>Despite the use of anti-platelet agents such as acetylsalicylic acid (ASA) and clopidogrel in coronary heart disease, some patients continue to suffer from atherothrombosis. This has stimulated development of platelet function assays to monitor treatment effects. However, it is still not recommended to change treatment based on results from platelet function assays. This study aimed to evaluate the capacity of a static platelet adhesion assay to detect platelet inhibiting effects of ASA and clopidogrel. The adhesion assay measures several aspects of platelet adhesion simultaneously, which increases the probability of finding conditions sensitive for anti-platelet treatment.</p> <p>Methods</p> <p>With a randomised cross-over design we evaluated the anti-platelet effects of ASA combined with clopidogrel as well as monotherapy with either drug alone in 29 patients with a recent acute coronary syndrome. Also, 29 matched healthy controls were included to evaluate intra-individual variability over time. Platelet function was measured by flow cytometry, serum thromboxane B<sub>2 </sub>(TXB<sub>2</sub>)-levels and by static platelet adhesion to different protein surfaces. The results were subjected to Principal Component Analysis followed by ANOVA, t-tests and linear regression analysis.</p> <p>Results</p> <p>The majority of platelet adhesion measures were reproducible in controls over time denoting that the assay can monitor platelet activity. Adenosine 5'-diphosphate (ADP)-induced platelet adhesion decreased significantly upon treatment with clopidogrel compared to ASA. Flow cytometric measurements showed the same pattern (r<sup>2 </sup>= 0.49). In opposite, TXB<sub>2</sub>-levels decreased with ASA compared to clopidogrel. Serum TXB<sub>2 </sub>and ADP-induced platelet activation could both be regarded as direct measures of the pharmacodynamic effects of ASA and clopidogrel respectively. Indirect pharmacodynamic measures such as adhesion to albumin induced by various soluble activators as well as SFLLRN-induced activation measured by flow cytometry were lower for clopidogrel compared to ASA. Furthermore, adhesion to collagen was lower for ASA and clopidogrel combined compared with either drug alone.</p> <p>Conclusion</p> <p>The indirect pharmacodynamic measures of the effects of ASA and clopidogrel might be used together with ADP-induced activation and serum TXB<sub>2 </sub>for evaluation of anti-platelet treatment. This should be further evaluated in future clinical studies where screening opportunities with the adhesion assay will be optimised towards increased sensitivity to anti-platelet treatment.</p
The GRAVITY+ Project: Towards All-sky, Faint-Science, High-Contrast Near-Infrared Interferometry at the VLTI
The GRAVITY instrument has been revolutionary for near-infrared
interferometry by pushing sensitivity and precision to previously unknown
limits. With the upgrade of GRAVITY and the Very Large Telescope Interferometer
(VLTI) in GRAVITY+, these limits will be pushed even further, with vastly
improved sky coverage, as well as faint-science and high-contrast capabilities.
This upgrade includes the implementation of wide-field off-axis
fringe-tracking, new adaptive optics systems on all Unit Telescopes, and laser
guide stars in an upgraded facility. GRAVITY+ will open up the sky to the
measurement of black hole masses across cosmic time in hundreds of active
galactic nuclei, use the faint stars in the Galactic centre to probe General
Relativity, and enable the characterisation of dozens of young exoplanets to
study their formation, bearing the promise of another scientific revolution to
come at the VLTI.Comment: Published in the ESO Messenge
Tuberculosis among people living with HIV/AIDS in the German ClinSurv HIV Cohort: long-term incidence and risk factors
BACKGROUND: Tuberculosis (TB) still presents a leading cause of morbidity and mortality among people living with HIV/AIDS (PLWHA), including those on antiretroviral therapy. In this study, we aimed to determine the long-term incidence density rate (IDR) of TB and risk factors among PLWHA in relation to combination antiretroviral therapy (cART)-status. METHODS: Data of PLWHA enrolled from 2001 through 2011 in the German ClinSurv HIV Cohort were investigated using survival analysis and Cox regression. RESULTS: TB was diagnosed in 233/11,693 PLWHA either at enrollment (Nâ=â62) or during follow-up (Nâ=â171). The TB IDR during follow-up was 0.37 cases per 100 person-years (PY) overall [95% CI, 0.32-0.43], and was higher among patients who never started cART and among patients originating from Sub-Saharan Africa (1.23 and 1.20 per 100PY, respectively). In two multivariable analyses, both patients (I) who never started cART and (II) those on cART shared the same risk factors for TB, namely: originating from Sub-Saharan Africa compared to Germany (I, hazard ratio (HR); [95% CI]) 4.05; [1.87-8.78] and II, HR 5.15 [2.76-9.60], CD4+ cell count <200 cells/ÎŒl (I, HR 8.22 [4.36-15.51] and II, HR 1.90 [1.14-3.15]) and viral load >5 log(10) copies/ml (I, HR 2.51 [1.33-4.75] and II, HR 1.77 [1.11-2.82]). Gender, age or HIV-transmission risk group were not independently associated with TB. CONCLUSION: In the German ClinSurv HIV cohort, patients originating from Sub-Saharan Africa, with low CD4+ cell count or high viral load at enrollment were at increased risk of TB even after cART initiation. As patients might be latently infected with Mycobacterium tuberculosis complex, early screening for latent TB infection and implementing isoniazid preventive therapy in line with available recommendations is crucial
Global variations in diabetes mellitus based on fasting glucose and haemogloblin A1c
Fasting plasma glucose (FPG) and haemoglobin A1c (HbA1c) are both used to diagnose
diabetes, but may identify different people as having diabetes. We used data from 117
population-based studies and quantified, in different world regions, the prevalence of
diagnosed diabetes, and whether those who were previously undiagnosed and detected
as having diabetes in survey screening had elevated FPG, HbA1c, or both. We developed
prediction equations for estimating the probability that a person without previously
diagnosed diabetes, and at a specific level of FPG, had elevated HbA1c, and vice versa.
The age-standardised proportion of diabetes that was previously undiagnosed, and
detected in survey screening, ranged from 30% in the high-income western region to 66%
in south Asia. Among those with screen-detected diabetes with either test, the agestandardised
proportion who had elevated levels of both FPG and HbA1c was 29-39%
across regions; the remainder had discordant elevation of FPG or HbA1c. In most low- and
middle-income regions, isolated elevated HbA1c more common than isolated elevated
FPG. In these regions, the use of FPG alone may delay diabetes diagnosis and
underestimate diabetes prevalence. Our prediction equations help allocate finite
resources for measuring HbA1c to reduce the global gap in diabetes diagnosis and
surveillance.peer-reviewe
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