1,878 research outputs found
A New Physical Performance Classification System for Elite Handball Players : Cluster Analysis
The aim of the present study was to identify different cluster groups of handball players according to their physical performance level assessed in a series of physical assessments, which could then be used to design a training program based on individual strengths and weaknesses, and to determine which of these variables best identified elite performance in a group of under-19 [U19] national level handball players. Players of the U19 National Handball team (n=16) performed a set of tests to determine: 10 m (ST(10)) and 20 m (ST(20)) sprint time, ball release velocity (BRv), countermovement jump (CMJ) height and squat jump (SJ) height. All players also performed an incremental-load bench press test to determine the 1 repetition maximum (1RM(est)), the load corresponding to maximum mean power (Load(MP)), the mean propulsive phase power at Load(MP) (P(MPP)MP) and the peak power at Load(MP) (P(PEAK)MP). Cluster analyses of the test results generated four groupings of players. The variables best able to discriminate physical performance were BRv, ST(20), 1RM(est), P(PEAK)MP and P(MPP)MP. These variables could help coaches identify talent or monitor the physical performance of athletes in their team. Each cluster of players has a particular weakness related to physical performance and therefore, the cluster results can be applied to a specific training programmed based on individual needs
A Targeted Sampling Strategy for Compressive Cryo Focused Ion Beam Scanning Electron Microscopy
Cryo Focused Ion-Beam Scanning Electron Microscopy (cryo FIB-SEM) enables
three-dimensional and nanoscale imaging of biological specimens via a slice and
view mechanism. The FIB-SEM experiments are, however, limited by a slow
(typically, several hours) acquisition process and the high electron doses
imposed on the beam sensitive specimen can cause damage. In this work, we
present a compressive sensing variant of cryo FIB-SEM capable of reducing the
operational electron dose and increasing speed. We propose two Targeted
Sampling (TS) strategies that leverage the reconstructed image of the previous
sample layer as a prior for designing the next subsampling mask. Our image
recovery is based on a blind Bayesian dictionary learning approach, i.e., Beta
Process Factor Analysis (BPFA). This method is experimentally viable due to our
ultra-fast GPU-based implementation of BPFA. Simulations on artificial
compressive FIB-SEM measurements validate the success of proposed methods: the
operational electron dose can be reduced by up to 20 times. These methods have
large implications for the cryo FIB-SEM community, in which the imaging of beam
sensitive biological materials without beam damage is crucial.Comment: Submitted to ICASSP 202
The Potential of Subsampling and Inpainting for Fast Low-Dose Cryo FIB-SEM Imaging and Tomography
Traditional image acquisition for cryo focused ion-beam scanning electron
microscopy tomography often sees thousands of images being captured over a
period of many hours, with immense data sets being produced. When imaging beam
sensitive materials, these images are often compromised by additional
constraints related to beam damage and the devitrification of the material
during imaging, which renders data acquisition both costly and unreliable.
Subsampling and inpainting are proposed as solutions for both of these aspects,
allowing fast and low-dose imaging to take place in the FIB-SEM without an
appreciable low in image quality. In this work, experimental data is presented
which validates subsampling and inpainting as a useful tool for convenient and
reliable data acquisition in a FIB-SEM, with new methods of handling
3-dimensional data being employed in context of dictionary learning and
inpainting algorithms using a newly developed microscope control software and
data recovery algorithm.Comment: In submission to "Microscopy and Microanalysis" journal. Authorship
reviewed from previous submissio
A Targeted Sampling Strategy for Compressive Cryo Focused Ion Beam Scanning Electron Microscopy
Cryo Focused Ion-Beam Scanning Electron Microscopy (cryo FIB-SEM) enables
three-dimensional and nanoscale imaging of biological specimens via a slice and
view mechanism. The FIB-SEM experiments are, however, limited by a slow
(typically, several hours) acquisition process and the high electron doses
imposed on the beam sensitive specimen can cause damage. In this work, we
present a compressive sensing variant of cryo FIB-SEM capable of reducing the
operational electron dose and increasing speed. We propose two Targeted
Sampling (TS) strategies that leverage the reconstructed image of the previous
sample layer as a prior for designing the next subsampling mask. Our image
recovery is based on a blind Bayesian dictionary learning approach, i.e., Beta
Process Factor Analysis (BPFA). This method is experimentally viable due to our
ultra-fast GPU-based implementation of BPFA. Simulations on artificial
compressive FIB-SEM measurements validate the success of proposed methods: the
operational electron dose can be reduced by up to 20 times. These methods have
large implications for the cryo FIB-SEM community, in which the imaging of beam
sensitive biological materials without beam damage is crucial
Understanding Russia's return to the Middle East
Over recent years, there has been a significant resurgence of Russian power and influence in the Middle East, which has been evident in the diplomatic and military intervention into Syria. This article identifies the principal factors behind Russia’s return to the region. First, there are domestic political influences with the coincidence of the uprisings in the Middle East, the so-called ‘Arab Spring,’ with large-scale domestic opposition protests within Russia during the elections in 2011–2012. Second, there is the role of ideas, most notably the growing anti-Westernism in Putin’s third presidential term, along with Russia’s own struggle against Islamist terrorism. These ideational factors contributed to Russia’s resolve to support the Assad government against both Western intervention and its domestic Islamist opposition. Third, Russia has benefited from a pragmatic and flexible approach in its engagement with the region. Moscow seeks to ensure that it is a critical actor for all the various states and political movements in the Middle East
Knotted optical vortices in exact solutions to Maxwell's equations
We construct a family of exact solutions to Maxwell's equations in which the
points of zero intensity form knotted lines topologically equivalent to a given
but arbitrary algebraic link. These lines of zero intensity, more commonly
referred to as optical vortices, and their topology are preserved as time
evolves and the fields have finite energy. To derive explicit expressions for
these new electromagnetic fields that satisfy the nullness property, we make
use of the Bateman variables for the Hopf field as well as complex polynomials
in two variables whose zero sets give rise to algebraic links. The class of
algebraic links includes not only all torus knots and links thereof, but also
more intricate cable knots. While the unknot has been considered before, the
solutions presented here show that more general knotted structures can also
arise as optical vortices in exact solutions to Maxwell's equations.Comment: 5 pages, 3 figures; revised abstract, introduction, and conclusion;
results unchange
Quantum state preparation and macroscopic entanglement in gravitational-wave detectors
Long-baseline laser-interferometer gravitational-wave detectors are operating
at a factor of 10 (in amplitude) above the standard quantum limit (SQL) within
a broad frequency band. Such a low classical noise budget has already allowed
the creation of a controlled 2.7 kg macroscopic oscillator with an effective
eigenfrequency of 150 Hz and an occupation number of 200. This result, along
with the prospect for further improvements, heralds the new possibility of
experimentally probing macroscopic quantum mechanics (MQM) - quantum mechanical
behavior of objects in the realm of everyday experience - using
gravitational-wave detectors. In this paper, we provide the mathematical
foundation for the first step of a MQM experiment: the preparation of a
macroscopic test mass into a nearly minimum-Heisenberg-limited Gaussian quantum
state, which is possible if the interferometer's classical noise beats the SQL
in a broad frequency band. Our formalism, based on Wiener filtering, allows a
straightforward conversion from the classical noise budget of a laser
interferometer, in terms of noise spectra, into the strategy for quantum state
preparation, and the quality of the prepared state. Using this formalism, we
consider how Gaussian entanglement can be built among two macroscopic test
masses, and the performance of the planned Advanced LIGO interferometers in
quantum-state preparation
Searching for a Stochastic Background of Gravitational Waves with LIGO
The Laser Interferometer Gravitational-wave Observatory (LIGO) has performed
the fourth science run, S4, with significantly improved interferometer
sensitivities with respect to previous runs. Using data acquired during this
science run, we place a limit on the amplitude of a stochastic background of
gravitational waves. For a frequency independent spectrum, the new limit is
. This is currently the most sensitive
result in the frequency range 51-150 Hz, with a factor of 13 improvement over
the previous LIGO result. We discuss complementarity of the new result with
other constraints on a stochastic background of gravitational waves, and we
investigate implications of the new result for different models of this
background.Comment: 37 pages, 16 figure
Measurement of the cross-section and charge asymmetry of bosons produced in proton-proton collisions at TeV with the ATLAS detector
This paper presents measurements of the and cross-sections and the associated charge asymmetry as a
function of the absolute pseudorapidity of the decay muon. The data were
collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with
the ATLAS experiment at the LHC and correspond to a total integrated luminosity
of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements
varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the
1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured
with an uncertainty between 0.002 and 0.003. The results are compared with
predictions based on next-to-next-to-leading-order calculations with various
parton distribution functions and have the sensitivity to discriminate between
them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables,
submitted to EPJC. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
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