352 research outputs found
A rare case of arterial avulsion presenting with occult blood loss following total hip arthroplasty: a case report
INTRODUCTION: Iatrogenic arterial damage during total hip replacement is a rare but potentially life- or limb-threatening complication. To the best of our knowledge, this is the first reported case of an avulsion injury to a posterior branch of the profunda femoral artery during primary hip arthroplasty. CASE PRESENTATION: We describe the case of a 55-year-old Caucasian man who underwent a total hip replacement. The patient's hemoglobin levels dropped postoperatively, but there was no obvious bleeding, hemodynamic instability, pulsatile mass, or limb ischemia. The patient's hemoglobin levels continued to drop despite nine units of transfused blood. Three days after surgery, the patient underwent an angiography that showed an avulsion injury to a posterior branch of the profunda femoral artery. The avulsion was ligated and the hematoma was evacuated. CONCLUSION: Vascular damage may present in many ways including obvious bleeding, haemodynamic instability, a pulsatile mass, limb ischemia, and occult blood loss. Any of these signs in isolation or in combination could represent a vascular injury and an urgent angiogram should be considered
Inference algorithms for gene networks: a statistical mechanics analysis
The inference of gene regulatory networks from high throughput gene
expression data is one of the major challenges in systems biology. This paper
aims at analysing and comparing two different algorithmic approaches. The first
approach uses pairwise correlations between regulated and regulating genes; the
second one uses message-passing techniques for inferring activating and
inhibiting regulatory interactions. The performance of these two algorithms can
be analysed theoretically on well-defined test sets, using tools from the
statistical physics of disordered systems like the replica method. We find that
the second algorithm outperforms the first one since it takes into account
collective effects of multiple regulators
Reverse Engineering Gene Networks with ANN: Variability in Network Inference Algorithms
Motivation :Reconstructing the topology of a gene regulatory network is one
of the key tasks in systems biology. Despite of the wide variety of proposed
methods, very little work has been dedicated to the assessment of their
stability properties. Here we present a methodical comparison of the
performance of a novel method (RegnANN) for gene network inference based on
multilayer perceptrons with three reference algorithms (ARACNE, CLR, KELLER),
focussing our analysis on the prediction variability induced by both the
network intrinsic structure and the available data.
Results: The extensive evaluation on both synthetic data and a selection of
gene modules of "Escherichia coli" indicates that all the algorithms suffer of
instability and variability issues with regards to the reconstruction of the
topology of the network. This instability makes objectively very hard the task
of establishing which method performs best. Nevertheless, RegnANN shows MCC
scores that compare very favorably with all the other inference methods tested.
Availability: The software for the RegnANN inference algorithm is distributed
under GPL3 and it is available at the corresponding author home page
(http://mpba.fbk.eu/grimaldi/regnann-supmat
Asymptomatic giant coronary aneurysm in an adolescent with Behcet's syndrome
<p>Abstract</p> <p>Objective</p> <p>Behcet's is an idiopathic multi-organ syndrome, which may have onset during childhood. Vascular involvement is uncommon, with rarely reported coronary aneurysm formation. We present a case report of a teenager girl who developed recalcitrant life-threatening Behcet's vasculitis, involving both small and large venous and arterial systems including a giant coronary aneurysm.</p> <p>Case report</p> <p>De-identified data were collected retrospectively in case report format. Although our sixteen year old female with Behcet's vasculitis had resolution of many arterial aneurysms, she had persistent venous thrombosis of large vessels, as well as persistent, giant arterial aneurysms requiring intra-arterial coiling of a lumbar artery and coronary bypass grafting despite intensive immunosuppression including glucocorticoids, cyclophosphamide, infliximab, methotrexate, azathioprine and intravenous immunoglobulin.</p> <p>Conclusions</p> <p>Vascular manifestations may be seen in Behcet's syndrome, including asymptomatic coronary aneurysm, which may be refractory to immunosuppression and ultimately require surgical intervention. Increased awareness is essential for prompt diagnosis and management.</p
Direct constraint on the distance of y2 Velorum from AMBER/VLTI observations
In this work, we present the first AMBER observations, of the Wolf-Rayet and
O (WR+O) star binary system y2 Velorum. The AMBER instrument was used with the
telescopes UT2, UT3, and UT4 on baselines ranging from 46m to 85m. It delivered
spectrally dispersed visibilities, as well as differential and closure phases,
with a resolution R = 1500 in the spectral band 1.95-2.17 micron. We interpret
these data in the context of a binary system with unresolved components,
neglecting in a first approximation the wind-wind collision zone flux
contribution. We show that the AMBER observables result primarily from the
contribution of the individual components of the WR+O binary system. We discuss
several interpretations of the residuals, and speculate on the detection of an
additional continuum component, originating from the free-free emission
associated with the wind-wind collision zone (WWCZ), and contributing at most
to the observed K-band flux at the 5% level. The expected absolute separation
and position angle at the time of observations were 5.1±0.9mas and
66±15° respectively. However, we infer a separation of
3.62+0.11-0.30 mas and a position angle of 73+9-11°. Our analysis thus
implies that the binary system lies at a distance of 368+38-13 pc, in agreement
with recent spectrophotometric estimates, but significantly larger than the
Hipparcos value of 258+41-31 pc
Calibration and Characterization of the IceCube Photomultiplier Tube
Over 5,000 PMTs are being deployed at the South Pole to compose the IceCube
neutrino observatory. Many are placed deep in the ice to detect Cherenkov light
emitted by the products of high-energy neutrino interactions, and others are
frozen into tanks on the surface to detect particles from atmospheric cosmic
ray showers. IceCube is using the 10-inch diameter R7081-02 made by Hamamatsu
Photonics. This paper describes the laboratory characterization and calibration
of these PMTs before deployment. PMTs were illuminated with pulses ranging from
single photons to saturation level. Parameterizations are given for the single
photoelectron charge spectrum and the saturation behavior. Time resolution,
late pulses and afterpulses are characterized. Because the PMTs are relatively
large, the cathode sensitivity uniformity was measured. The absolute photon
detection efficiency was calibrated using Rayleigh-scattered photons from a
nitrogen laser. Measured characteristics are discussed in the context of their
relevance to IceCube event reconstruction and simulation efforts.Comment: 40 pages, 12 figure
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
An improved method for measuring muon energy using the truncated mean of dE/dx
The measurement of muon energy is critical for many analyses in large
Cherenkov detectors, particularly those that involve separating
extraterrestrial neutrinos from the atmospheric neutrino background. Muon
energy has traditionally been determined by measuring the specific energy loss
(dE/dx) along the muon's path and relating the dE/dx to the muon energy.
Because high-energy muons (E_mu > 1 TeV) lose energy randomly, the spread in
dE/dx values is quite large, leading to a typical energy resolution of 0.29 in
log10(E_mu) for a muon observed over a 1 km path length in the IceCube
detector. In this paper, we present an improved method that uses a truncated
mean and other techniques to determine the muon energy. The muon track is
divided into separate segments with individual dE/dx values. The elimination of
segments with the highest dE/dx results in an overall dE/dx that is more
closely correlated to the muon energy. This method results in an energy
resolution of 0.22 in log10(E_mu), which gives a 26% improvement. This
technique is applicable to any large water or ice detector and potentially to
large scintillator or liquid argon detectors.Comment: 12 pages, 16 figure
Search for Relativistic Magnetic Monopoles with IceCube
We present the first results in the search for relativistic magnetic
monopoles with the IceCube detector, a subsurface neutrino telescope located in
the South Polar ice cap containing a volume of 1 km. This analysis
searches data taken on the partially completed detector during 2007 when
roughly 0.2 km of ice was instrumented. The lack of candidate events
leads to an upper limit on the flux of relativistic magnetic monopoles of
\Phi_{\mathrm{90%C.L.}}\sim 3\e{-18}\fluxunits for . This is a
factor of 4 improvement over the previous best experimental flux limits up to a
Lorentz boost below . This result is then interpreted for a
wide range of mass and kinetic energy values.Comment: 11 pages, 11 figures. v2 is minor text edits, no changes to resul
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