1,183 research outputs found
Kernel-Level Interception and Applications on Mobile Devices
The techniques of kernel-level system call interception are well known today for many different operating systems. This work starts with transferring these technique to the Windows CE type of operating systems. Afterwards, two current problems are solved. The first solution uses the technique for dynamic malware analysis with a sandbox approach, extending previous solutions in terms of effectiveness. The second solution enhances the expressiveness of security policies by implementing the concept of a reference monitor on the operating system level. Windows CE based devices are now enabled to enforce sophisticated security policies without the need to change the underlying operating system
Chromosomal Gains and Losses in Uveal Melanomas Detected by Comparative Genomic Hybridization
Eleven uveal melanomas were analyzed using comparative genomic hybridization (CGH). The most abundant genetic changes were loss of chromosome 3, overrepresentation of 6p, loss of 6q, and multiplication of 8q. The smallest overrepresented regions on 6p and 8q were 6pterp21 and 8q24qter, respectively. Several additional gains and losses of chromosome segments were repeatedly observed, the most frequent one being loss of 9p (three cases). Monosomy 3 appeared to be a marker for ciliary body involvement.
CGH data were compared with the results of chromosome banding. Some alterations, e.g., gains of 6p and losses of 6q, were observed with higher frequencies after CGH, while others, e.g., 9p deletions, were detected only by CGH. The data suggest some similarities of cytogenetic alterations between cutaneous and uveal melanoma. In particular, the 9p deletions are of interest due to recent reports about the location of a putative tumor-suppressor gene for cutaneous malignant melanoma in this region
Infrared regulators and SCETII
We consider matching from SCETI, which includes ultrasoft and collinear
particles, onto SCETII with soft and collinear particles at one loop. Keeping
the external fermions off their mass shell does not regulate all IR divergences
in both theories. We give a new prescription to regulate infrared divergences
in SCET. Using this regulator, we show that soft and collinear modes in SCETII
are sufficient to reproduce all the infrared divergences of SCETI. We explain
the relationship between IR regulators and an additional mode proposed for
SCETII.Comment: 9 pages. Added discussion about relationship between IR regulators
and messenger mode
On the breaking of collinear factorization in QCD
We investigate the breakdown of collinear factorization for non-inclusive
observables in hadron-hadron collisions. For pure QCD processes, factorization
is violated at the three-loop level and it has a structure identical to that
encountered previously in the case of super-leading logarithms. In particular,
it is driven by the non-commutation of Coulomb/Glauber gluon exchanges with
other soft exchanges. Beyond QCD, factorization may be violated at the two-loop
level provided that the hard subprocess contains matrix element contributions
with phase differences between different colour topologies.Comment: Version 2: minor improvements for journal publicatio
Metaphase and Interphase Cytogenetics with Alu-PCR-amplified Yeast Artificial Chromosome Clones Containing the BCR Gene and the Protooncogenes c-raf-1, c-fms, and c-erbB-21
A human yeast artificial chromosome (YAC) library was screened by polymerase chain reaction with oligonucleotide primers defined for DNA sequences of the BCR gene and the protooncogenes c-raf-1, c-fms, and c-erB-2. Alu-PCR-generated human DNA sequences were obtained from the respective YAC clones and used for fluorescence in situ hybridization experiments under suppression conditions. After chromosomal in situ suppression hybridization to GTG-banded human prometaphase chromosomes, seven of nine initially isolated YAC clones yielded strong signals exclusively in the chromosome bands containing the respective genes. Two clones yielded additional signals on other chromosomes and were excluded from further tests. The band-specific YACs were successfully applied to visualize specific structural chromosome aberrations in peripheral blood cells from patients with myelodysplasia exhibiting del(5)(q13q34), chronic myeloid leukemia and acute lymphocytic leukemia with t(9;22)(q34;q11), acute promyelocytic leukemia (M3) with t(15;17)(q22;q21), and in a cell line established from a proband with the constitutional translocation t(3;8)(p14.2;q24). In addition to the analysis of metaphase spreads, we demonstrate the particular usefulness of these YAC clones in combination with whole chromosome painting to analyze specific chromosome aberrations directly in the interphase nucleus
Visible-to-telecom quantum frequency conversion of light from a single quantum emitter
Quantum frequency conversion (QFC), a nonlinear optical process in which the
frequency of a quantum light field is altered while conserving its
non-classical correlations, was first demonstrated 20 years ago. Meanwhile, it
is considered an essential tool for the implementation of quantum repeaters
since it allows for interfacing quantum memories with telecom-wavelength
photons as quantum information carriers. Here we demonstrate efficient (>30%)
QFC of visible single photons (711 nm) emitted by a quantum dot (QD) to a
telecom wavelength (1,313 nm). Analysis of the first and second-order coherence
before and after wavelength conversion clearly proves that important
properties, such as the coherence time and photon antibunching, are fully
conserved during the frequency translation process. Our findings underline the
great potential of single photon sources on demand in combination with QFC as a
promising technique for quantum repeater schemes.Comment: 11 pages, 4 figure
String Breaking as a Mixing Phenomenon in the SU(2) Higgs Model
We study the potential of a static quark anti-quark pair in the confinement
``phase'' of the SU(2) Higgs model. Around separation r_b, the confining string
of the gauge field breaks by formation of a dynamical pair of light quarks. The
ground state and first excited state static potentials are determined by a
variational technique from a matrix correlation in which suitably smeared gauge
and Higgs fields enter. Our results at beta=2.4 clearly show string breaking
(r_b ~ 1.9r_0). The investigation of properly defined overlaps confirms the
interpretation of string breaking as a level crossing phenomenon between
string-type and meson-type states. We study the scaling properties of the
static potentials along a line of constant physics, varying the lattice spacing
by a factor of 2. Our results show compatibility with scaling within tiny
errors.Comment: 21 pages, 9 figure
Dissolution Power, Confidence Votes, and Policymaking in Parliamentary Democracies
There is striking variation across parliamentary democracies in the power of prime ministers to employ two prominent procedures to resolve legislative conflict: the vote of confidence and the dissolution of parliament. While previous contributions in comparative politics have investigated each of these two fundamental institutions in isolation, I develop a simple unified model to unbundle how this richer variety of institutional configurations shapes political bargaining over policy. The analysis clarifies that the effects of the confidence vote and dissolution power interact. As a consequence, there can be a non-monotonic effect of increasing prime ministers’ formal power on their ability to shape the policy compromise. Counterintuitively, introducing dissolution power makes the prime minister worse off under some conditions. These results suggest new directions for empirical research on the consequences of parliamentary institutions for legislative politics and policy. They also lay analytical foundations for explaining institutional variation and reforms
Etiology, risk factors and sex differences in ischemic stroke in the Ludwigshafen stroke study, a population-based stroke registry
Background: Stroke etiology in ischemic stroke guides preventive measures and etiological stroke subgroups may show considerable differences between both sexes. In a population-based stroke registry we analyzed etiological subgroups of ischemic stroke and calculated sex-specific incidence and mortality rates. Methods: The Ludwigshafen Stroke Study is a prospective ongoing population-based stroke registry. Multiple overlapping methods of case ascertainment were used to identify all patients with incident stroke or transient ischemic attack. Modified TOAST ( Trial of Org 10172 in Acute Stroke Treatment) criteria were applied for subgroup analysis in ischemic stroke. Results: Out of 626 patients with first-ever ischemic stroke in 2006 and 2007, women (n = 327) were older (73.5 8 12.6 years) than men (n = 299; 69.7 8 11.5 years; p < 0.001). The age-adjusted incidence rate of ischemic stroke was significantly higher in men (1.37; 95% CI 1.20–1.56) than in women (1.12; 95% CI 0.97–1.29; p = 0.04). Cardioembolism (n = 219; 35.0%), smallartery
occlusion (n = 164; 26.2%), large-artery atherosclerosis (n = 98; 15.7%) and ‘probable atherothrombotic stroke’
(n = 84; 13.4%) were common subgroups of ischemic stroke.
Stroke due to large-artery atherosclerosis (p = 0.025), current smoking (p = 0.008), history of smoking (p 85 years) was detected. Conclusions: Cardioembolism is the main source for ischemic stroke in our population. Etiology of ischemic stroke differs between sexes, with large-artery atherosclerotic stroke and associated diseases (coronary artery disease and peripheral artery disease) being more common in men
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