10 research outputs found
All-particle cosmic ray energy spectrum measured with 26 IceTop stations
We report on a measurement of the cosmic ray energy spectrum with the IceTop
air shower array, the surface component of the IceCube Neutrino Observatory at
the South Pole. The data used in this analysis were taken between June and
October, 2007, with 26 surface stations operational at that time, corresponding
to about one third of the final array. The fiducial area used in this analysis
was 0.122 km^2. The analysis investigated the energy spectrum from 1 to 100 PeV
measured for three different zenith angle ranges between 0{\deg} and 46{\deg}.
Because of the isotropy of cosmic rays in this energy range the spectra from
all zenith angle intervals have to agree. The cosmic-ray energy spectrum was
determined under different assumptions on the primary mass composition. Good
agreement of spectra in the three zenith angle ranges was found for the
assumption of pure proton and a simple two-component model. For zenith angles
{\theta} < 30{\deg}, where the mass dependence is smallest, the knee in the
cosmic ray energy spectrum was observed between 3.5 and 4.32 PeV, depending on
composition assumption. Spectral indices above the knee range from -3.08 to
-3.11 depending on primary mass composition assumption. Moreover, an indication
of a flattening of the spectrum above 22 PeV were observed.Comment: 38 pages, 17 figure
Search for Gravitational Waves from Intermediate Mass Binary Black Holes
We present the results of a weakly modeled burst search for gravitational
waves from mergers of non-spinning intermediate mass black holes (IMBH) in the
total mass range 100--450 solar masses and with the component mass ratios
between 1:1 and 4:1. The search was conducted on data collected by the LIGO and
Virgo detectors between November of 2005 and October of 2007. No plausible
signals were observed by the search which constrains the astrophysical rates of
the IMBH mergers as a function of the component masses. In the most efficiently
detected bin centered on 88+88 solar masses, for non-spinning sources, the rate
density upper limit is 0.13 per Mpc^3 per Myr at the 90% confidence level.Comment: 13 pages, 4 figures: data for plots and archived public version at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=62326, see also the
public announcement at http://www.ligo.org/science/Publication-S5IMBH
Effect of polyethylene glycol on in vitro gas production of some non-leguminous forage trees in tropical region of the south of Mexico
The aim of this study was to evaluate the chemical
composition of five foliages, and the effect of adding
PEG during incubation on in vitro gas production
(GP), metabolizable energy (ME), partitioning factor
(PF24h), in vitro organic matter digestibility (OMD),
short chain fatty acids (SCFA) and microbial biomass
production (MBP) as tools to detect the adverse effect
of tannins in the foliage of non-leguminous trees.The objective of the current study was to
evaluate the chemical composition and the in vitro gas
production (GP) of some non-leguminous forage trees
in presence or absence of polyethylene glycol (PEG).
Guazuma ulmifolia, Crescentia alata, Ficus glabrata,
Ficus cotinifolia, Spondias purpurea, Mangifera
indica, Licania arborea, Simira mexicana were collected
during the rainy season, in the Bejucos locality,
State of Mexico. Metabolizable energy (ME), partitioning
factor (PF24h), in vitro organic matter digestibility
(OMD), short chain fatty acids (SCFA) and
microbial biomass production (MBP) were estimated
as tools to detect the adverse effects of tannins in tree
foliage. The chemical composition data were analyzed
in a random design, and the in vitro digestion
parameters on a randomized design with 8 9 2
factorial arrangement. Chemical composition showed
a wide variation (P\0.05) between species. The use
of PEG increased (P\0.05) GP from the foliage of S.
purpurea, L. arborea, F. glabrata and G. ulmifolia,
showing activity of total phenolics and condensed
tannins. Similarly, ME (5.9 MJ kg-1 DM), OMD
(354.5 g kg-1 DM) and SCFA (2.3 mol/150 mL)
increased (P\0.05); it was higher for S. purpurea,
because of the PEG addition effect. The PF24h and
MBP were different between species (P\0.05), and
decreased due to PEG addition (P\0.05); the species
with lower production was S. purpurea. It could be
concluded that S. purpurea and F. cotinifolia represent
important sources of fodder for livestock in the south
region of Mexico
All-particle cosmic ray energy spectrum measured with 26 IceTop stations
We report on a measurement of the cosmic ray energy spectrum with the IceTop air shower array, the surface component of the IceCube Neutrino Observatory at the South Pole. The data used in this analysis were taken between June and October, 2007, with 26 surface stations operational at that time, corresponding to about one third of the final array. The fiducial area used in this analysis was 0.122 km2. The analysis investigated the energy spectrum from 1 to 100 PeV measured for three different zenith angle ranges between 0° and 46°. Because of the isotropy of cosmic rays in this energy range the spectra from all zenith angle intervals have to agree. The cosmic-ray energy spectrum was determined under different assumptions on the primary mass composition. Good agreement of spectra in the three zenith angle ranges was found for the assumption of pure proton and a simple two-component model. For zenith angles θ < 30°, where the mass dependence is smallest, the knee in the cosmic ray energy spectrum was observed at about 4 PeV, with a spectral index above the knee of about −3.1. Moreover, an indication of a flattening of the spectrum above 22 PeV was observed
Cosmic ray composition and energy spectrum from 1–30 PeV using the 40-string configuration of IceTop and IceCube
The mass composition of high energy cosmic rays depends on their production, acceleration, and propagation. The study of cosmic ray composition can therefore reveal hints of the origin of these particles. At the South Pole, the IceCube Neutrino Observatory is capable of measuring two components of cosmic ray air showers in coincidence: the electromagnetic component at high altitude (2835 m) using the IceTop surface array, and the muonic component above ∼1 TeV using the IceCube array. This unique detector arrangement provides an opportunity for precision measurements of the cosmic ray energy spectrum and composition in the region of the knee and beyond. We present the results of a neural network analysis technique to study the cosmic ray composition and the energy spectrum from 1 PeV to 30 PeV using data recorded using the 40-string/40-station configuration of the IceCube Neutrino Observatory. </p
BJS commission on surgery and perioperative care post-COVID-19
Coronavirus disease 2019 (COVID-19) was declared a pandemic by the WHO on 11 March 2020 and global surgical practice was compromised. This Commission aimed to document and reflect on the changes seen in the surgical environment during the pandemic, by reviewing colleagues' experiences and published evidence
Higher harmonic anisotropic flow measurements of charged particles in Pb-Pb collisions at √sNN=2.76 TeV
We report on the first measurement of the triangular v3, quadrangular v4, and pentagonal v5 charged particle flow in Pb–Pb collisions at √sNN= 2.76 TeV measured with the ALICE detector at the CERN Large Hadron Collider. We show that the triangular flow can be described in terms of the initial spatial anisotropy and its fluctuations, which provides strong constraints on its origin. In the most central events, where the elliptic flow v2 and v3 have similar magnitude, a double peaked structure in the two-particle azimuthal correlations is observed, which is often interpreted as a Mach cone response to fast partons. We show that this structure can be naturally explained from the measured anisotropic flow Fourier coefficients