Characterizing varieties of colength 644

Let A be an associative algebra over a field F of characteristic zero, and let n(A), n=1,2,, be the sequence of cocharacters of A. For every n1, let ln(A) denote the nth colength of A, counting the number of Sn-irreducibles appearing in n(A). In this article, we classify the algebras A such that the sequence of colengths ln(A), n=1,2,, is bounded by four. Moreover we construct a finite number of algebras A1,, Ad, such that ln(A)4 if and only if A1,, Ad var(A)

Codimensions of algebras with additional structures

Let A be an associative algebra endowed with an automorphism or an antiautomorphism phi of order <= 2. One associates to A, in a natural way, a numerical sequence c(n)(phi)(A), n = 1, 2, ... , called the sequence of phi-codimensions of A which is the main tool for the quantitative investigation of the polynomial identities satisfied by A. In [13] it was proved that such a sequence is eventually nondecreasing in case phi is an antiautomorphism. Here we prove that it still holds in case phi is an automorphism and present some recent results about the asymptotics of c(n)(phi)(A)

Real Exchange Rates, Preferences, and Incomplete Markets: Evidence, 1961-2001

Many international macroeconomic models link the real exchange rate to a ratio of marginal utilities. We examine this link empirically, allowing the marginal utility of consumption to depend on government expenditure, real money balances, or external habit. We also consider two environments with incomplete asset markets; one with exogenously missing markets but an endogenous discount rate that anchors the distribution of wealth and one with endogenous market segmentation. Although none of these satisfies theoretical and over-identifying restrictions for every country, utility with external habit persistence provides the best match with real exchange rates for OECD countries between 1961 and 2001.real exchange rate, consumption, marginal utility

Real exchange rates, preferences, and incomplete markets: Evidence, 1961-2001

Many international macroeconomic models link the real exchange rate to a ratio of marginal utilities. We examine this link empirically, allowing the marginal utility of consumption to depend on government expenditure, real money balances, or external habit. We also consider two environments with incomplete asset markets; one with exogenously missing markets but an endogenous discount rate that anchors the distribution of wealth and one with endogenous market segmentation. Although none of these satisfies theoretical and over-identifying restrictions for every country, utility with external habit persistence provides the best match with real exchange rates for OECD countries between 1961 and 2001

Pressure effects on the transition temperature and the magnetic field penetration depth in the pyrochlore superconductor RbOs_2O_6

We report magnetization measurements under high hydrostatic pressure in the newly discovered pyrochlore superconductor RbOs_2O_6 (T_c\simeq6.3K at p=0). A pronounced and {\it positive} pressure effect (PE) on T_c with dT_c/dp =0.090(1)K/kbar was observed, whereas no PE on the magnetic penetration depth \lambda was detected. The relative pressure shift of T_c [ dlnT_c/dp \simeq 1.5%/kbar] is comparable with the highest values obtained for highly underdoped high-temperature cuprate superconductors. Our results suggest that RbOs_2O_6 is an adiabatic BCS-type superconductor.Comment: 11 pages, 4 figure

Second- and Third-Line Chemotherapy in Advanced Gastric Cancer: a Real-Life Clinical Picture

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Study of the magnetic penetration depth in RbOs_2O_6

Measurements of the magnetic field penetration depth \lambda in the pyrochlore superconductor RbOs_2O_6 (T_c\simeq6.3 K) were carried out by means of the muon-spin-rotation (\muSR) technique. At low temperatures \lambda^{-2}(T) saturates and becomes constant below T\simeq 0.2T_c, in agreement with what is expected for weak-coupled s-wave BCS superconductors. The value of \lambda at T=0 was found to be in the range of 250 nm to 300 nm. \muSR and equilibrium magnetization measurements both reveal that at low temperatures $\lambda$ is almost (at the level of 10%) independent of the applied magnetic field. This result suggests that the superconducting energy gap in RbOs_2O_6 is isotropic.Comment: 8 pages, 9 figure

Embolic strokes of undetermined source: prevalence and patient features in the ESUS Global Registry

Background: Recent evidence supports that most non-lacunar cryptogenic strokes are embolic. Accordingly, these strokes have been designated as embolic strokes of undetermined source (ESUS). Aims: We undertook an international survey to characterize the frequency and clinical features of ESUS patients across global regions. Methods: Consecutive patients hospitalized for ischemic stroke were retrospectively surveyed from 19 stroke research centers in 19 different countries to collect patients meeting criteria for ESUS. Results: Of 2144 patients with recent ischemic stroke, 351 (16%, 95% CI 15% to 18%) met ESUS criteria, similar across global regions (range 16% to 21%), and an additional 308 (14%) patients had incomplete evaluation required for ESUS diagnosis. The mean age of ESUS patients (62 years; SD = 15) was significantly lower than the 1793 non-ESUS ischemic stroke patients (68 years, p ≤ 0.001). Excluding patients with atrial fibrillation (n = 590, mean age = 75 years), the mean age of the remaining 1203 non-ESUS ischemic stroke patients was 64 years (p = 0.02 vs. ESUS patients). Among ESUS patients, hypertension, diabetes, and prior stroke were present in 64%, 25%, and 17%, respectively. Median NIHSS score was 4 (interquartile range 2–8). At discharge, 90% of ESUS patients received antiplatelet therapy and 7% received anticoagulation. Conclusions: This cross-sectional global sample of patients with recent ischemic stroke shows that one-sixth met criteria for ESUS, with additional ESUS patients likely among those with incomplete diagnostic investigation. ESUS patients were relatively young with mild strokes. Antiplatelet therapy was the standard antithrombotic therapy for secondary stroke prevention in all global regions

Bioavailability in soils

The consumption of locally-produced vegetables by humans may be an important exposure pathway for soil contaminants in many urban settings and for agricultural land use. Hence, prediction of metal and metalloid uptake by vegetables from contaminated soils is an important part of the Human Health Risk Assessment procedure. The behaviour of metals (cadmium, chromium, cobalt, copper, mercury, molybdenum, nickel, lead and zinc) and metalloids (arsenic, boron and selenium) in contaminated soils depends to a large extent on the intrinsic charge, valence and speciation of the contaminant ion, and soil properties such as pH, redox status and contents of clay and/or organic matter. However, chemistry and behaviour of the contaminant in soil alone cannot predict soil-to-plant transfer. Root uptake, root selectivity, ion interactions, rhizosphere processes, leaf uptake from the atmosphere, and plant partitioning are important processes that ultimately govern the accumulation ofmetals and metalloids in edible vegetable tissues. Mechanistic models to accurately describe all these processes have not yet been developed, let alone validated under field conditions. Hence, to estimate risks by vegetable consumption, empirical models have been used to correlate concentrations of metals and metalloids in contaminated soils, soil physico-chemical characteristics, and concentrations of elements in vegetable tissues. These models should only be used within the bounds of their calibration, and often need to be re-calibrated or validated using local soil and environmental conditions on a regional or site-specific basis.Mike J. McLaughlin, Erik Smolders, Fien Degryse, and Rene Rietr

Intrachromosomal tandem duplication and repeat expansion during attempts to inactivate the subtelomeric essential gene GSH1 in Leishmania

Gamma-glutamylcysteine synthetase encoded by GSH1 is the rate-limiting enzyme in the biosynthesis of glutathione and trypanothione in Leishmania. Attempts to generate GSH1 null mutants by gene disruption failed in Leishmania infantum. Removal of even a single allele invariably led to the generation of an extra copy of GSH1, maintaining two intact wild-type alleles. In the second and even third round of inactivation, the markers integrated at the homologous locus but always preserved two intact copies of GSH1. We probed into the mechanism of GSH1 duplication. GSH1 is subtelomeric on chromosome 18 and Southern blot analysis indicated that a 10-kb fragment flanked by 466-bp direct repeated sequences was duplicated in tandem on the same chromosomal allele each time GSH1 was targeted. Polymerase chain reaction analysis and sequencing confirmed the generation of novel junctions created at the level of the 466-bp repeats consequent to locus duplication. In loss of heterozygosity attempts, the same repeated sequences were utilized for generating extrachromosomal circular amplicons. Our results are consistent with break-induced replication as a mechanism for the generation of this regional polyploidy to compensate for the inactivation of an essential gene. This chromosomal repeat expansion through repeated sequences could be implicated in locus duplication in Leishmania