179 research outputs found
PPPC 4 DM ID: A Poor Particle Physicist Cookbook for Dark Matter Indirect Detection
We provide ingredients and recipes for computing signals of TeV-scale Dark
Matter annihilations and decays in the Galaxy and beyond. For each DM channel,
we present the energy spectra of electrons and positrons, antiprotons,
antideuterons, gamma rays, neutrinos and antineutrinos e, mu, tau at
production, computed by high-statistics simulations. We estimate the Monte
Carlo uncertainty by comparing the results yielded by the Pythia and Herwig
event generators. We then provide the propagation functions for charged
particles in the Galaxy, for several DM distribution profiles and sets of
propagation parameters. Propagation of electrons and positrons is performed
with an improved semi-analytic method that takes into account
position-dependent energy losses in the Milky Way. Using such propagation
functions, we compute the energy spectra of electrons and positrons,
antiprotons and antideuterons at the location of the Earth. We then present the
gamma ray fluxes, both from prompt emission and from Inverse Compton scattering
in the galactic halo. Finally, we provide the spectra of extragalactic gamma
rays. All results are available in numerical form and ready to be consumed.Comment: 57 pages with many figures and tables. v4: updated to include a 125
higgs boson, computation and discussion of extragalactic spectra corrected,
some other typos fixed; all these corrections and updates are reflected on
the numerical ingredients available at
http://www.marcocirelli.net/PPPC4DMID.html they correspond to Release 2.
Quark mixing from softly broken symmetries
Quark flavor mixing may originate in the soft breaking of horizontal
symmetries. Those symmetries, which in the simplest case are three family U(1)
groups, are obeyed only by the dimension-4 Yukawa couplings and lead, when
unbroken, to the absence of mixing. Their breaking may arise from the
dimension-3 mass terms of SU(2)-singlet vector-like quarks. Those gauge-singlet
mass terms break the horizontal symmetries at a scale much higher than the
Fermi scale, yet softly, leading to quark mixing while the quark masses remain
unsuppressed.Comment: 9 pages, plain Latex, no figure
Dirty black holes: Quasinormal modes
In this paper, we investigate the asymptotic nature of the quasinormal modes
for "dirty" black holes -- generic static and spherically symmetric spacetimes
for which a central black hole is surrounded by arbitrary "matter" fields. We
demonstrate that, to the leading asymptotic order, the [imaginary] spacing
between modes is precisely equal to the surface gravity, independent of the
specifics of the black hole system.
Our analytical method is based on locating the complex poles in the first
Born approximation for the scattering amplitude. We first verify that our
formalism agrees, asymptotically, with previous studies on the Schwarzschild
black hole. The analysis is then generalized to more exotic black hole
geometries. We also extend considerations to spacetimes with two horizons and
briefly discuss the degenerate-horizon scenario.Comment: 15 pages; uses iopart.cls setstack.sty; V2: one additional reference
added, no physics changes; V3: two extra references, minor changes in
response to referee comment
SU(5) Unified Theories from Intersecting Branes
We discuss the first string theory examples of three generation
non-supersymmetric SU(5) and {\em flipped} SU(5) GUTS, which break to the
Standard model at low energy, without extra matter and/or gauge group factors.
Our GUT examples are based on IIA orientifolds with D6-branes
intersecting at non-trivial angles. These theories necessarily satisfy RR
tadpoles and are free of NSNS tadpoles as the complex structure moduli are
frozen (even though a dilaton tadpole remains) to discrete values. We identify
appropriately the bifundamental Higgses responsible for electroweak symmetry
breaking. In this way, the neutrino see-saw mechanism get nicely realized in
these constructions. Moreover, as baryon number is not a gauged symmetry gauge
mediated dimension six operators do contribute to proton decay; however proton
lifetime may be safely enhanced by appropriately choosing a high GUT scale. An
accompanying natural doublet-triplet splitting guarantees the suppression of
scalar mediated proton decay modes and the stability of triplet scalar masses
against higher dimensional non-renormalizable operators.Comment: 26 pages, 5 figures; no changes, one comment added in the
introductio
Notes on Amanita section Validae in Hainan Island, China
Hainan is the second largest island in China with the most extensive and well-preserved tropical forests and is also the largest island of the Indo Burma Biodiversity Hotspot. It provides in situ conservation for the unique ecosystem of the island. Recent studies have shown that there are diverse fungal species in Hainan. In this study, about 40 collections of the genus Amanita have been studied based on the morphology and molecular systematics, including 35 Chinese specimens (24 from Hainan, and eleven from other regions) and three specimens from other countries (Singapore and Malaysia). In total, five new species belonging to Amanita section Validae are described: A. cacaina, A. parvigrisea, A. pseudofritillaria, A. pseudosculpta, and A. yangii. Amanita parvifritillaria is recorded for the first time in Hainan. It is also the first report of this fungus occurring, outside Yunnan Province, China. Among the five new species, two are unique in this section because of the appendiculate pileus margin and the absence of an annulus. Based on these new findings, the diagnosis of the section Validae should be slightly modified to include a few species with appendiculate margin and the lack of annulus
Epidemiological and Clinical Characteristics of Melioidosis Caused by Gentamicin-Susceptible Burkholderia pseudomallei in Sarawak, Malaysia
Burkholderia pseudomallei, the causative agent of melioidosis, is intrinsically resistant to a broad range of antibiotics, including aminoglycosides. In Sarawak, Malaysia, a high proportion of melioidosis cases are caused by gentamicin-susceptible isolates. There are limited epidemiological and clinical data on these infections.
Methods. We conducted a retrospective study of culture-confirmed melioidosis among adults admitted to Bintulu Hospital in Sarawak, Malaysia, from January 2011 until December 2016.
One hundred forty-eight adults with culture-confirmed melioidosis were identified. Of 129 (87%) tested, 84 (65%)
had gentamicin-susceptible B pseudomallei. The average annual incidence of melioidosis was 12.3 per 100 000 population, with marked variation between districts ranging from 5.8 to 29.3 per 100 000 population. Rural districts had higher incidences of melioidosis and overwhelmingly larger proportions of gentamicin-susceptible B pseudomallei infection. Significantly more patients with gentamicin-susceptible infection had no identified risk factors, with diabetes less frequently present in this group. Ninety-eight percent had acute presentations. Pneumonia, reported in 71%, was the most common presentation. Splenic abscesses were found in 54% of those imaged. Bacteremia was present in 88%; septic shock occurred in 47%. Forty-five (35%) patients died. No differences in clinical, laboratory, or outcome characteristics were noted between gentamicin-susceptible and gentamicin-resistant infections.
Gentamicin-susceptible B pseudomallei infections are common in Sarawak and dominate in the high-incidence rural interior regions. Clinical manifestations and outcomes are the same as for gentamicin-resistant B pseudomallei infections.
Further studies are required to determine if all gentamicin-susceptible B pseudomallei infections in Sarawak are clonal and to ascertain their environmental drivers and niches
Mechanistic modelling of dynamic MRI data predicts that tumour heterogeneity decreases therapeutic response
Mechanistic modelling of dynamic MRI data predicts that tumour heterogeneity decreases therapeutic respons
A crowdsourced global data set for validating built-up surface layers
Several global high-resolution built-up surface products have emerged over the last five years, taking full advantage of open sources of satellite data such as Landsat and Sentinel. However, these data sets require validation that is independent of the producers of these products. To fill this gap, we designed a validation sample set of 50 K locations using a stratified sampling approach independent of any existing global built-up surface products. We launched a crowdsourcing campaign using Geo-Wiki (https://www.geo-wiki.org/) to visually interpret this sample set for built-up surfaces using very high-resolution satellite images as a source of reference data for labelling the samples, with a minimum of five validations per sample location. Data were collected for 10 m sub-pixels in an 80 × 80 m grid to allow for geo-registration errors as well as the application of different validation modes including exact pixel matching to majority or percentage agreement. The data set presented in this paper is suitable for the validation and inter-comparison of multiple products of built-up areas
- …
