392 research outputs found
The WKB Approximation without Divergences
In this paper, the WKB approximation to the scattering problem is developed
without the divergences which usually appear at the classical turning points. A
detailed procedure of complexification is shown to generate results identical
to the usual WKB prescription but without the cumbersome connection formulas.Comment: 13 pages, TeX file, to appear in Int. J. Theor. Phy
Automatic and controlled attentional orienting in the elderly: A dual-process view of the positivity effect
Mouse tracking to explore motor inhibition processes in go/no-go and stop signal tasks
Response inhibition relies on both proactive and reactive mechanisms that exert a synergic control on goal-directed actions. It is typically evaluated by the go/no-go (GNG) and the stop signal task (SST) with response recording based on the key-press method. However, the analysis of discrete variables (i.e., present or absent responses) registered by key-press could be insufficient to capture dynamic aspects of inhibitory control. Trying to overcome this limitation, in the present study we used a mouse tracking procedure to characterize movement profiles related to proactive and reactive inhibition. A total of fifty-three participants performed a cued GNG and an SST. The cued GNG mainly involves proactive control whereas the reactive component is mainly engaged in the SST. We evaluated the velocity profile from mouse trajectories both for responses obtained in the Go conditions and for inhibitory failures. Movements were classified as one-shot when no corrections were observed. Multi-peaked velocity profiles were classified as non-one-shot. A higher proportion of one-shot movements was found in the SST compared to the cued GNG when subjects failed to inhibit responses. This result suggests that proactive control may be responsible for unsmooth profiles in inhibition failures, supporting a differentiation between these tasks
An increased burden of rare exonic variants in NRXN1 microdeletion carriers is likely to enhance the penetrance for autism spectrum disorder.
Autism spectrum disorder (ASD) is characterized by a complex polygenic background, but with the unique feature of a subset of cases (~15%-30%) presenting a rare large-effect variant. However, clinical interpretation in these cases is often complicated by incomplete penetrance, variable expressivity and different neurodevelopmental trajectories. NRXN1 intragenic deletions represent the prototype of such ASD-associated susceptibility variants. From chromosomal microarrays analysis of 104 ASD individuals, we identified an inherited NRXN1 deletion in a trio family. We carried out whole-exome sequencing and deep sequencing of mitochondrial DNA (mtDNA) in this family, to evaluate the burden of rare variants which may contribute to the phenotypic outcome in NRXN1 deletion carriers. We identified an increased burden of exonic rare variants in the ASD child compared to the unaffected NRXN1 deletion-transmitting mother, which remains significant if we restrict the analysis to potentially deleterious rare variants only (P = 6.07
7 10-5 ). We also detected significant interaction enrichment among genes with damaging variants in the proband, suggesting that additional rare variants in interacting genes collectively contribute to cross the liability threshold for ASD. Finally, the proband's mtDNA presented five low-level heteroplasmic mtDNA variants that were absent in the mother, and two maternally inherited variants with increased heteroplasmic load. This study underlines the importance of a comprehensive assessment of the genomic background in carriers of large-effect variants, as penetrance modulation by additional interacting rare variants to might represent a widespread mechanism in neurodevelopmental disorders
Multi-systemic alterations by chronic exposure to a low dose of bisphenol a in drinking water: Effects on inflammation and nad+-dependent deacetylase sirtuin1 in lactating and weaned rats
Bisphenol A (BPA) is largely used as a monomer in some types of plastics. It accumulates in tissues and fluids and is able to bypass the placental barrier, affecting various organs and systems. Due to huge developmental processes, children, foetuses, and neonates could be more sensitive to BPA-induced toxicity. To investigate the multi-systemic effects of chronic exposure to a low BPA dose (100 µg/L), pregnant Wistar rats were exposed to BPA in drinking water during gestation and lactation. At weaning, newborn rats received the same treatments as dams until sex maturation. Free and conjugated BPA levels were measured in plasma and adipose tissue; the size of cerebral ventricles was analysed in the brain; morpho-functional and molecular analyses were carried out in the liver with a focus on the expression of inflammatory cytokines and Sirtuin 1 (Sirt1). Higher BPA levels were found in plasma and adipose tissue from BPA treated pups (17 PND) but not in weaned animals. Lateral cerebral ventricles were significantly enlarged in lactating and weaned BPA-exposed animals. In addition, apart from microvesicular steatosis, liver morphology did not exhibit any statistically significant difference for morphological signs of inflammation, hypertrophy, or macrovesicular steatosis, but the expression of inflammatory cytokines, Sirt1, its natural antisense long non-coding RNA (Sirt1-AS LncRNA) and histone deacetylase 1 (Hdac1) were affected in exposed animals. In conclusion, chronic exposure to a low BPA dose could increase the risk for disease in adult life as a consequence of higher BPA circulating levels and accumulation in adipose tissue during the neonatal period
Molecular absorption lines toward star-forming regions : a comparative study of HCO+, HNC, HCN, and CN
Aims. The comparative study of several molecular species at the origin of the
gas phase chemistry in the diffuse interstellar medium (ISM) is a key input in
unraveling the coupled chemical and dynamical evolution of the ISM. Methods.
The lowest rotational lines of HCO+, HCN, HNC, and CN were observed at the
IRAM-30m telescope in absorption against the \lambda 3 mm and \lambda 1.3 mm
continuum emission of massive star-forming regions in the Galactic plane. The
absorption lines probe the gas over kiloparsecs along these lines of sight. The
excitation temperatures of HCO+ are inferred from the comparison of the
absorptions in the two lowest transitions. The spectra of all molecular species
on the same line of sight are decomposed into Gaussian velocity components.
Most appear in all the spectra of a given line of sight. For each component, we
derived the central opacity, the velocity dispersion, and computed the
molecular column density. We compared our results to the predictions of
UV-dominated chemical models of photodissociation regions (PDR models) and to
those of non-equilibrium models in which the chemistry is driven by the
dissipation of turbulent energy (TDR models). Results. The molecular column
densities of all the velocity components span up to two orders of magnitude.
Those of CN, HCN, and HNC are linearly correlated with each other with mean
ratios N(HCN)/N(HNC) = 4.8 1.3 and N(CN)/N(HNC) = 34 12, and more
loosely correlated with those of HCO+, N(HNC)/N(HCO+) = 0.5 0.3,
N(HCN)/N(HCO+) = 1.9 0.9, and N(CN)/N(HCO+) = 18 9. These ratios
are similar to those inferred from observations of high Galactic latitude lines
of sight, suggesting that the gas sampled by absorption lines in the Galactic
plane has the same chemical properties as that in the Solar neighbourhood. The
FWHM of the Gaussian velocity components span the range 0.3 to 3 km s-1 and
those of the HCO+ lines are found to be 30% broader than those of CN-bearing
molecules. The PDR models fail to reproduce simultaneously the observed
abundances of the CN-bearing species and HCO+, even for high-density material
(100 cm-3 < nH < 104 cm-3). The TDR models, in turn, are able to reproduce the
observed abundances and abundance ratios of all the analysed molecules for the
moderate gas densities (30 cm-3 < nH < 200 cm-3) and the turbulent energy
observed in the diffuse interstellar medium. Conclusions. Intermittent
turbulent dissipation appears to be a promising driver of the gas phase
chemistry of the diffuse and translucent gas throughout the Galaxy. The details
of the dissipation mechanisms still need to be investigated
Reversal of <i>MYB </i>-dependent suppression of <i>MAFB </i>expression overrides leukaemia phenotype in MLL-rearranged AML
Abstract The transcription factor MYB plays a pivotal role in haematopoietic homoeostasis and its aberrant expression is involved in the genesis and maintenance of acute myeloid leukaemia (AML). We have previously demonstrated that not all AML subtypes display the same dependency on MYB expression and that such variability is dictated by the nature of the driver mutation. However, whether this difference in MYB dependency is a general trend in AML remains to be further elucidated. Here, we investigate the role of MYB in human leukaemia by performing siRNA-mediated knock-down in cell line models of AML with different driver lesions. We show that the characteristic reduction in proliferation and the concomitant induction of myeloid differentiation that is observed in MLL-rearranged and t(8;21) leukaemias upon MYB suppression is not seen in AML cells with a complex karyotype. Transcriptome analyses revealed that MYB ablation produces consensual increase of MAFB expression in MYB-dependent cells and, interestingly, the ectopic expression of MAFB could phenocopy the effect of MYB suppression. Accordingly, in silico stratification analyses of molecular data from AML patients revealed a reciprocal relationship between MYB and MAFB expression, highlighting a novel biological interconnection between these two factors in AML and supporting new rationales of MAFB targeting in MLL-rearranged leukaemias
Cognitive disorders in patients with chronic kidney disease: specificities of clinical assessment
Neurocognitive disorders are frequent among chronic kidney disease (CKD) patients. Identifying and characterizing cognitive impairment (CI) can help to assess the ability of adherence to CKD risk reduction strategy, identify potentially reversible causes of cognitive decline, modify pharmacotherapy, educate the patient and caregiver and provide appropriate patient and caregiver support. Numerous factors are associated with the development and progression of CI in CKD patients and various conditions can influence the results of cognitive assessment in these patients. Here we review clinical warning signs that should lead to cognitive screening; conditions frequent in CKD at risk to interfere with cognitive testing or performance, including specificities of cognitive assessment in dialysis patients or after kidney transplantation; and available tests for screening and observed cognitive patterns in CKD patients
Engine Gaseous, Aerosol Precursor and Particulated Flight Altitude Conditions
The overall objective of the NASA Atmospheric Effects of Aviation Project (AEAP) is to develop scientific bases for assessing atmospheric impacts of the exhaust emissions by both current and future fleets of subsonic and supersonic aircraft. Among the six primary elements of the AEAP is Emissions Characterization. The objective of the Emission Characterization effort is to determine the exhaust emission constituents and concentrations at the engine exit plane. The specific objective of this engine test is to obtain a database of gaseous and particulate emissions as a function of fuel sulfur and engine operating conditions. The database of the particulate emission properties is to be used as a comparative baseline with subsequent flight measurement. The engine used in this test was a Pratt & Whitney F1OO-200E turbofan engine. Aviation fuel (Jet A) with a range of fuel sulfur was used. Low and high sulfur values are limited by commercially available fuels and by fuel specification limits of O.3% by weight. Test matrix was set by parametrically varying the combustor inlet temperature (T(sub 3) between idle and maximum power setting at simulated SLS and up to five other altitudes for each fuel. Four diagnostic systems, extractive and non-intrusive, were assembled for the gaseous and particulate emissions characterization measurements study. NASA extractive system includes smoke meter and analyzers for measurement of CO, CO2, NO, NOx, O2, total unburnt hydrocarbons (THC), and SO2. Particulate emissions were characterized by University of Missouri-Rolla Mobile Aerosol Sampling System. A chemical ionization mass spectrometer from the Air Force Research Laboratory at Hanscom AFB was used to measure SO2 and HNO3. Aerodyne Research. Inc. used infrared tunable diode laser absorption to measure SO2, SO3, NO, H2O and CO2
- …