292 research outputs found
Constraining warm dark matter with cosmic shear power spectra
We investigate potential constraints from cosmic shear on the dark matter
particle mass, assuming all dark matter is made up of light thermal relic
particles. Given the theoretical uncertainties involved in making cosmological
predictions in such warm dark matter scenarios we use analytical fits to linear
warm dark matter power spectra and compare (i) the halo model using a mass
function evaluated from these linear power spectra and (ii) an analytical fit
to the non-linear evolution of the linear power spectra. We optimistically
ignore the competing effect of baryons for this work. We find approach (ii) to
be conservative compared to approach (i). We evaluate cosmological constraints
using these methods, marginalising over four other cosmological parameters.
Using the more conservative method we find that a Euclid-like weak lensing
survey together with constraints from the Planck cosmic microwave background
mission primary anisotropies could achieve a lower limit on the particle mass
of 2.5 keV.Comment: 26 pages, 9 figures, minor changes to match the version accepted for
publication in JCA
Wavy Strings: Black or Bright?
Recent developments in string theory have brought forth a considerable
interest in time-dependent hair on extended objects. This novel new hair is
typically characterized by a wave profile along the horizon and angular
momentum quantum numbers in the transverse space. In this work, we
present an extensive treatment of such oscillating black objects, focusing on
their geometric properties. We first give a theorem of purely geometric nature,
stating that such wavy hair cannot be detected by any scalar invariant built
out of the curvature and/or matter fields. However, we show that the tidal
forces detected by an infalling observer diverge at the `horizon' of a black
string superposed with a vibration in any mode with . The same
argument applied to longitudinal () waves detects only finite tidal
forces. We also provide an example with a manifestly smooth metric, proving
that at least a certain class of these longitudinal waves have regular
horizons.Comment: 45 pages, latex, no figure
Dietary intake and risk of non-severe hypoglycemia in adolescents with type 1 diabetes
Aims To determine the association between dietary intake and risk of non-severe hypoglycemia in adolescents with type 1 diabetes. Methods Type 1 adolescents from a randomized trial wore a blinded continuous glucose monitoring (CGM) system at baseline for one week in free-living conditions. Dietary intake was calculated as the average from two 24-h dietary recalls. Non-severe hypoglycemia was defined as having blood glucose < 70 mg/dL for ≥ 10 min but not requiring external assistance, categorized as daytime and nocturnal (11 PM–7AM). Data were analyzed using logistic regression models. Results Among 98 participants with 14,277 h of CGM data, 70 had daytime hypoglycemia, 66 had nocturnal hypoglycemia, 55 had both, and 17 had neither. Soluble fiber and protein intake were positively associated with both daytime and nocturnal hypoglycemia. Glycemic index, monounsaturated fat, and polyunsaturated fat were negatively associated with daytime hypoglycemia only. Adjusting for total daily insulin dose per kilogram eliminated all associations. Conclusions Dietary intake was differentially associated with daytime and nocturnal hypoglycemia. Over 80% of type 1 adolescents had hypoglycemia in a week, which may be attributed to the mismatch between optimal insulin dose needed for each meal and actually delivered insulin dose without considering quality of carbohydrate and nutrients beyond carbohydrate
On Some New Black String Solutions in Three Dimensions
We derive several new solutions in three-dimensional stringy gravity. The
solutions are obtained with the help of string duality transformations. They
represent stationary configurations with horizons, and are surrounded by
(quasi) topologically massive Abelian gauge hair, in addition to the dilaton
and the Kalb-Ramond axion. Our analysis suggests that there exists a more
general family, where our solutions are special limits. Finally, we use the
generating technique recently proposed by Garfinkle to construct a traveling
wave on the extremal variant of one of our solutions.Comment: revtex, 38 pages including 3 figure
Inflation: flow, fixed points and observables to arbitrary order in slow roll
I generalize the inflationary flow equations of Hoffman and Turner to
arbitrary order in slow roll. This makes it possible to study the predictions
of slow roll inflation in the full observable parameter space of tensor/scalar
ratio , spectral index , and running . It also becomes
possible to identify exact fixed points in the parameter flow. I numerically
evaluate the flow equations to fifth order in slow roll for a set of randomly
chosen initial conditions and find that the models cluster strongly in the
observable parameter space, indicating a ``generic'' set of predictions for
slow roll inflation. I comment briefly on the the interesting proposed
correspondence between flow in inflationary parameter space and renormalization
group flow in a boundary conformal field theory.Comment: 16 pages, 7 figures. LaTeX. V4: Fixed important error in numerical
constant in the second-order slow roll expressions for the observables r, n,
and dn/dlog(k). See footnote after Eq. (48). New figures, minor changes to
conclusions. Supersedes version published in Phys. Rev.
Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at TeV
Inclusive transverse momentum spectra of primary charged particles in Pb-Pb
collisions at = 2.76 TeV have been measured by the ALICE
Collaboration at the LHC. The data are presented for central and peripheral
collisions, corresponding to 0-5% and 70-80% of the hadronic Pb-Pb cross
section. The measured charged particle spectra in and GeV/ are compared to the expectation in pp collisions at the same
, scaled by the number of underlying nucleon-nucleon
collisions. The comparison is expressed in terms of the nuclear modification
factor . The result indicates only weak medium effects ( 0.7) in peripheral collisions. In central collisions,
reaches a minimum of about 0.14 at -7GeV/ and increases
significantly at larger . The measured suppression of high- particles is stronger than that observed at lower collision energies,
indicating that a very dense medium is formed in central Pb-Pb collisions at
the LHC.Comment: 15 pages, 5 captioned figures, 3 tables, authors from page 10,
published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/98
Natural product derivative Gossypolone inhibits Musashi family of RNA-binding proteins
Background: The Musashi (MSI) family of RNA-binding proteins is best known for the role in post-transcriptional regulation of target mRNAs. Elevated MSI1 levels in a variety of human cancer are associated with up-regulation of Notch/Wnt signaling. MSI1 binds to and negatively regulates translation of Numb and APC (adenomatous polyposis coli), negative regulators of Notch and Wnt signaling respectively. Methods: Previously, we have shown that the natural product (-)-gossypol as the first known small molecule inhibitor of MSI1 that down-regulates Notch/Wnt signaling and inhibits tumor xenograft growth in vivo. Using a fluorescence polarization (FP) competition assay, we identified gossypolone (Gn) with a > 20-fold increase in Ki value compared to (-)-gossypol. We validated Gn binding to MSI1 using surface plasmon resonance, nuclear magnetic resonance, and cellular thermal shift assay, and tested the effects of Gn on colon cancer cells and colon cancer DLD-1 xenografts in nude mice. Results: In colon cancer cells, Gn reduced Notch/Wnt signaling and induced apoptosis. Compared to (-)-gossypol, the same concentration of Gn is less active in all the cell assays tested. To increase Gn bioavailability, we used PEGylated liposomes in our in vivo studies. Gn-lip via tail vein injection inhibited the growth of human colon cancer DLD-1 xenografts in nude mice, as compared to the untreated control (P < 0.01, n = 10). Conclusion: Our data suggest that PEGylation improved the bioavailability of Gn as well as achieved tumor-targeted delivery and controlled release of Gn, which enhanced its overall biocompatibility and drug efficacy in vivo. This provides proof of concept for the development of Gn-lip as a molecular therapy for colon cancer with MSI1/MSI2 overexpression
An introduction to the SCOUT-AMMA stratospheric aircraft, balloons and sondes campaign in West Africa, August 2006: rationale and roadmap
A multi-platform field measurement campaign involving aircraft and balloons took place over West Africa between 26 July and 25 August 2006, in the frame of the concomitant AMMA Special Observing Period and SCOUT-O3 African tropical activities.
Specifically aiming at sampling the upper troposphere and lower stratosphere, the high-altitude research aircraft M55 Geophysica was deployed in Ouagadougou (12.3° N, 1.7° W), Burkina Faso, in conjunction with the German D-20 Falcon, while a series of stratospheric balloon and sonde flights were conducted from Niamey (13.5° N, 2.0° E), Niger.
The stratospheric aircraft and balloon flights intended to gather experimental evidence for a better understanding of large scale transport, assessing the effect of lightning on NOx production, and studying the impact of intense mesoscale convective systems on water, aerosol, dust and chemical species in the upper troposphere and lower stratosphere. The M55 Geophysica carried out five local and four transfer flights between southern Europe and the Sahel and back, while eight stratospheric balloons and twenty-nine sondes were flown from Niamey.
These experiments allowed a characterization of the tropopause and lower stratosphere of the region. We provide here an overview of the campaign activities together with a description of the general meteorological situation during the flights and a summary of the observations accomplished
Holography, diffeomorphisms, and scaling violations in the CMB
We analyze diffeomorphism invariance in inflationary spacetimes regulated by a boundary at late time. We present the action for quadratic fluctuations in the presence of a boundary, and verify that it is gauge invariant precisely when the correct local counterterms are included. The scaling behavior of bulk correlation functions at the boundary is determined by Callan-Symanzik equations which predict scaling violations in agreement with the standard inflationary predictions for spectral indices of the CMB.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49149/2/jhep072004062.pd
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