825 research outputs found
Screening disability insurance applications
This paper investigates the effects of stricter screening of disability insurance applications. A large-scale experiment was setup where in two of the 26 Dutch regions case workers of the disability insurance administration were instructed to screen applications more stringently. The empirical results show that stricter screening reduces long-term sickness absenteeism and disability insurance applications. We find evidence for direct effects of stricter screening on work resumption during the period of sickness absence and for self-screening by potential disability insurance applicants. Stricter screening seems to improve targeting efficiency, without inducing negative spillover effects to the inflow into unemployment insurance. The costs of stricter screening are only a small fraction of the monetary benefits.Disability insurance; experiment; policy evaluation; sickness absenteeism; self-screening
Biliary Bicarbonate Secretion Constitutes a Protective Mechanism against Bile Acid-Induced Injury in Man
Background: Cholangiocytes expose a striking resistance against bile acids: while other cell types, such as hepatocytes, are susceptible to bile acid-induced toxicity and apoptosis already at micromolar concentrations, cholangiocytes are continuously exposed to millimolar concentrations as present in bile. We present a hypothesis suggesting that biliary secretion of HCO(3)(-) in man serves to protect cholangiocytes against bile acid-induced damage by fostering the deprotonation of apolar bile acids to more polar bile salts. Here, we tested if bile acid-induced toxicity is pH-dependent and if anion exchanger 2 (AE2) protects against bile acid-induced damage. Methods: A human cholangiocyte cell line was exposed to chenodeoxycholate (CDC), or its glycine conjugate, from 0.5 mM to 2.0 mM at pH 7.4, 7.1, 6.7 or 6.4, or after knockdown of AE2. Cell viability and apoptosis were determined by WST and caspase-3/-7 assays, respectively. Results: Glycochenodeoxycholate (GCDC) uptake in cholangiocytes is pH-dependent. Furthermore, CDC and GCDC (pK(a) 4-5) induce cholangiocyte toxicity in a pH-dependent manner: 0.5 mM CDC and 1 mM GCDC at pH 7.4 had no effect on cell viability, but at pH 6.4 decreased viability by >80% and increased caspase activity almost 10- and 30-fold, respectively. Acidification alone had no effect. AE2 knockdown led to 3- and 2-fold enhanced apoptosis induced by 0.75 mM CDC or 2 mM GCDC at pH 7.4. Discussion: These data support our hypothesis of a biliary HCO(3)(-) umbrella serving to protect human cholangiocytes against bile acid-induced injury. AE2 is a key contributor to this protective mechanism. The development and progression of cholangiopathies, such as primary biliary cirrhosis, may be a consequence of genetic and acquired functional defects of genes involved in maintaining the biliary HCO(3)(-) umbrella. Copyright (C) 2011 S. Karger AG, Base
Noncommutative geometry inspired black holes in higher dimensions at the LHC
When embedding models of noncommutative geometry inspired black holes into
the peridium of large extra dimensions, it is natural to relate the
noncommutativity scale to the higher-dimensional Planck scale. If the Planck
scale is of the order of a TeV, noncommutative geometry inspired black holes
could become accessible to experiments. In this paper, we present a detailed
phenomenological study of the production and decay of these black holes at the
Large Hadron Collider (LHC). Noncommutative inspired black holes are relatively
cold and can be well described by the microcanonical ensemble during their
entire decay. One of the main consequences of the model is the existence of a
black hole remnant. The mass of the black hole remnant increases with
decreasing mass scale associated with noncommutative and decreasing number of
dimensions. The experimental signatures could be quite different from previous
studies of black holes and remnants at the LHC since the mass of the remnant
could be well above the Planck scale. Although the black hole remnant can be
very heavy, and perhaps even charged, it could result in very little activity
in the central detectors of the LHC experiments, when compared to the usual
anticipated black hole signatures. If this type of noncommutative inspired
black hole can be produced and detected, it would result in an additional mass
threshold above the Planck scale at which new physics occurs.Comment: 21 pages, 7 figure
Top Quarks as a Window to String Resonances
We study the discovery potential of string resonances decaying to
final state at the LHC. We point out that top quark pair production is a
promising and an advantageous channel for studying such resonances, due to
their low Standard Model background and unique kinematics. We study the
invariant mass distribution and angular dependence of the top pair production
cross section via exchanges of string resonances. The mass ratios of these
resonances and the unusual angular distribution may help identify their
fundamental properties and distinguish them from other new physics. We find
that string resonances for a string scale below 4 TeV can be detected via the
channel, either from reconstructing the semi-leptonic
decay or recent techniques in identifying highly boosted tops.Comment: 22 pages, 6 figure
Wolbachia in the flesh: symbiont intensities in germ-line and somatic tissues challenge the conventional view of Wolbachia transmission routes
Symbionts can substantially affect the evolution and ecology of their hosts. The investigation of the tissue-specific distribution of symbionts (tissue tropism) can provide important insight into host-symbiont interactions. Among other things, it can help to discern the importance of specific transmission routes and potential phenotypic effects. The intracellular bacterial symbiont Wolbachia has been described as the greatest ever panzootic, due to the wide array of arthropods that it infects. Being primarily vertically transmitted, it is expected that the transmission of Wolbachia would be enhanced by focusing infection in the reproductive tissues. In social insect hosts, this tropism would logically extend to reproductive rather than sterile castes, since the latter constitute a dead-end for vertically transmission. Here, we show that Wolbachia are not focused on reproductive tissues of eusocial insects, and that non-reproductive tissues of queens and workers of the ant Acromyrmex echinatior, harbour substantial infections. In particular, the comparatively high intensities of Wolbachia in the haemolymph, fat body, and faeces, suggest potential for horizontal transmission via parasitoids and the faecal-oral route, or a role for Wolbachia modulating the immune response of this host. It may be that somatic tissues and castes are not the evolutionary dead-end for Wolbachia that is commonly thought
On encoding symbol degrees of array BP-XOR codes
Low density parity check (LDPC) codes, LT codes and digital fountain techniques have received significant attention from both academics and industry in the past few years. By employing the underlying ideas of efficient Belief Propagation (BP) decoding process (also called iterative message passing decoding process) on binary erasure channels (BEC) in LDPC codes, Wang has recently introduced the concept of array BP-XOR codes and showed the necessary and sufficient conditions for MDS [k + 2,k] and [n,2] array BP-XOR codes. In this paper, we analyze the encoding symbol degree requirements for array BP-XOR codes and present new necessary conditions for array BP-XOR codes. These new necessary conditions are used as a guideline for constructing several array BP-XOR codes and for presenting a complete characterization (necessary and sufficient conditions) of degree two array BP-XOR codes and for designing new edge-colored graphs. Meanwhile, these new necessary conditions are used to show that the codes by Feng, Deng, Bao, and Shen in IEEE Transactions on Computers are incorrect
Is Our Universe Natural?
It goes without saying that we are stuck with the universe we have.
Nevertheless, we would like to go beyond simply describing our observed
universe, and try to understand why it is that way rather than some other way.
Physicists and cosmologists have been exploring increasingly ambitious ideas
that attempt to explain why certain features of our universe aren't as
surprising as they might first appear.Comment: Invited review for Nature, 11 page
Statistical modeling of ground motion relations for seismic hazard analysis
We introduce a new approach for ground motion relations (GMR) in the
probabilistic seismic hazard analysis (PSHA), being influenced by the extreme
value theory of mathematical statistics. Therein, we understand a GMR as a
random function. We derive mathematically the principle of area-equivalence;
wherein two alternative GMRs have an equivalent influence on the hazard if
these GMRs have equivalent area functions. This includes local biases. An
interpretation of the difference between these GMRs (an actual and a modeled
one) as a random component leads to a general overestimation of residual
variance and hazard. Beside this, we discuss important aspects of classical
approaches and discover discrepancies with the state of the art of stochastics
and statistics (model selection and significance, test of distribution
assumptions, extreme value statistics). We criticize especially the assumption
of logarithmic normally distributed residuals of maxima like the peak ground
acceleration (PGA). The natural distribution of its individual random component
(equivalent to exp(epsilon_0) of Joyner and Boore 1993) is the generalized
extreme value. We show by numerical researches that the actual distribution can
be hidden and a wrong distribution assumption can influence the PSHA negatively
as the negligence of area equivalence does. Finally, we suggest an estimation
concept for GMRs of PSHA with a regression-free variance estimation of the
individual random component. We demonstrate the advantages of event-specific
GMRs by analyzing data sets from the PEER strong motion database and estimate
event-specific GMRs. Therein, the majority of the best models base on an
anisotropic point source approach. The residual variance of logarithmized PGA
is significantly smaller than in previous models. We validate the estimations
for the event with the largest sample by empirical area functions. etc
The brain's response to pleasant touch: an EEG investigation of tactile caressing
Somatosensation as a proximal sense can have a strong impact on our attitude toward physical objects and other human beings. However, relatively little is known about how hedonic valence of touch is processed at the cortical level. Here we investigated the electrophysiological correlates of affective tactile sensation during caressing of the right forearm with pleasant and unpleasant textile fabrics. We show dissociation between more physically driven differential brain responses to the different fabrics in early somatosensory cortex - the well-known mu-suppression (10-20 Hz) - and a beta-band response (25-30 Hz) in presumably higher-order somatosensory areas in the right hemisphere that correlated well with the subjective valence of tactile caressing. Importantly, when using single trial classification techniques, beta-power significantly distinguished between pleasant and unpleasant stimulation on a single trial basis with high accuracy. Our results therefore suggest a dissociation of the sensory and affective aspects of touch in the somatosensory system and may provide features that may be used for single trial decoding of affective mental states from simple electroencephalographic measurements
Gene and protein expression of glucose transporter 1 and glucose transporter 3 in human laryngeal cancer—the relationship with regulatory hypoxia-inducible factor-1α expression, tumor invasiveness, and patient prognosis
Increased glucose uptake mediated by glucose
transporters and reliance on glycolysis are common features
of malignant cells. Hypoxia-inducible factor-1α supports the
adaptation of hypoxic cells by inducing genes related to
glucose metabolism. The contribution of glucose transporter
(GLUT) and hypoxia-inducible factor-1α (HIF-1α) activity to
tumor behavior and their prognostic value in head and neck
cancers remains unclear. The aim of this study was to examine
the predictive value of GLUT1, GLUT3, and HIF-1α messenger
RNA (mRNA)/protein expression as markers of tumor
aggressiveness and prognosis in laryngeal cancer. The level of
hypoxia/metabolic marker genes was determined in 106 squamous
cell laryngeal cancer (SCC) and 73 noncancerous
matched mucosa (NCM) controls using quantitative realtime
PCR. The related protein levels were analyzed by
Western blot. Positive expression of SLC2A1, SLC2A3, and
HIF-1α genes was noted in 83.9, 82.1, and 71.7 % of SCC
specimens and in 34.4, 59.4, and 62.5 % of laryngeal cancer
samples. Higher levels of mRNA/protein for GLUT1 and
HIF-1α were noted in SCC compared to NCM (p<0.05).
SLC2A1 was found to have a positive relationship with grade,
tumor front grading (TFG) score, and depth and mode of
invasion (p<0.05). SLC2A3 was related to grade and invasion
type (p<0.05). There were also relationships of HIF-1α with
pTNM, TFG scale, invasion depth and mode, tumor recurrences,
and overall survival (p<0.05). In addition, more advanced
tumors were found to be more likely to demonstrate
positive expression of these proteins. In conclusion, the
hypoxia/metabolic markers studied could be used as molecular
markers of tumor invasiveness in laryngeal cancer.This work was supported, in part, by the statutory
fund of the Department of Cytobiochemistry, University of Łódź, Poland
(506/811), and by grant fromtheNational Science Council, Poland (N403
043 32/2326)
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