Some effects of Mach number and geometry on sonic boom

Mach number and geometry effects on level of sonic boom overpressure and applicability of Whitham theory to calculation of sonic boo

Women cotton farmers: Their perceptions and experiences with transgenic varieties: A case study for Colombia

This paper explores gender differences in cotton cultivation and looks into the perceptions and experiences of women and men with transgenic varieties. With few exceptions, researchers in the area of impact evaluation of crop biotechnology have only marginally included gender considerations in their work. This exploratory pilot study was developed in order to incorporate gender into our quantitative evaluation work. This study used a participatory and descriptive approach that allowed us to listen to women and men farmers' perceptions and insights. The project was conducted in the main cotton-producing regions of Colombia where a handful of transgenic varieties have been in the market for the past six years.crop biotechnology, Genetically modified crops, Genetic engineering, Cotton, Gender,

Uprolides N, O and P from the Panamanian Octocoral Eunicea succinea.

Three new diterpenes, uprolide N (1), uprolide O (2), uprolide P (3) and a known one, dolabellane (4), were isolated from the CH₂Cl₂-MeOH extract of the gorgonian octocoral Eunicea succinea, collected from Bocas del Toro, on the Caribbean coast of Panama. Their structures were determined using spectroscopic analyses, including 1D and 2D NMR and high-resolution mass spectrometry (HRMS) together with molecular modeling studies. Compounds 1-3 displayed anti-inflammatory properties by inhibiting production of Tumor Necrosis Factor (TNF) and Interleukin (IL)-6 induced by lipopolysaccharide (LPS) in murine macrophages

Thinly Traded Growth Stocks: A Joint Examination of Transparency in Communication and the Trading Platform

When thinly traded growth stocks (TTGS) listed on a secondary exchange experience difficulty in gaining investors' attention, one possible solution is to increase the intensity of disclosure. However, if the stock is traded on a quote-driven system, market makers can collude to maintain wide bid-ask spreads that discourage firms from disclosing. As a result, TTGS traded on a quote-driven system can face a liquidity trap that can prevent them from harvesting the benefits of increased disclosure activities. In this paper, we argue that the well-documented negative relation between disclosure and the bid-ask spread is likely to be moderated by the type of protocol chosen by exchanges to handle the trading of TTGS. To test our theory we use a unique setting created by the introduction of a hybrid order-driven protocol for TTGS in the UK. Following an increase in the disclosure activity by a TTGS, we find that the magnitudes of the predicted reductions in the bid-ask spreads are dependent on whether the TTGS switch their trading protocols. © 2013 © 2013 European Accounting Association

Hydrological control of large hurricane-induced lahars: evidence from rainfall-runoff modeling, seismic and video monitoring

Abstract. The Volcán de Colima, one of the most active volcanoes in Mexico, is commonly affected by tropical rains related to hurricanes that form over the Pacific Ocean. In 2011, 2013 and 2015 hurricanes Jova, Manuel and Patricia, respectively, triggered tropical storms that deposited up to 400 mm of rain in 36 h, with maximum intensities of 50 mm h −1. The effects were devastating, with the formation of multiple lahars along La Lumbre and Montegrande ravines, which are the most active channels in sediment delivery on the south-southwest flank of the volcano. Deep erosion along the river channels and several marginal landslides were observed, and the arrival of block-rich flow fronts resulted in damages to bridges and paved roads in the distal reaches of the ravines. The temporal sequence of these flow events is reconstructed and analyzed using monitoring data (including video images, seismic records and rainfall data) with respect to the rainfall characteristics and the hydrologic response of the watersheds based on rainfall-runoff numerical simulation. For the studied events, lahars occurred 5–6 h after the onset of rainfall, lasted several hours and were characterized by several pulses with block-rich fronts and a maximum flow discharge of 900 m3 s −1. Rainfall-runoff simulations were performer using the SCS-curve number and the Green–Ampt infiltration models, providing a similar result in the detection of simulated maximum watershed peaks discharge. Results show different behavior for the arrival times of the first lahar pulses that correlate with the simulated catchment's peak discharge for La Lumbre ravine and with the peaks in rainfall intensity for Montegrande ravine. This different behavior is related to the area and shape of the two watersheds. Nevertheless, in all analyzed cases, the largest lahar pulse always corresponds with the last one and correlates with the simulated maximum peak discharge of these catchments. Data presented here show that flow pulses within a lahar are not randomly distributed in time, and they can be correlated with rainfall peak intensity and/or watershed discharge, depending on the watershed area and shape. This outcome has important implications for hazard assessment during extreme hydro-meteorological events, as it could help in providing real-time alerts. A theoretical rainfall distribution curve was designed for Volcán de Colima based on the rainfall and time distribution of hurricanes Manuel and Patricia. This can be used to run simulations using weather forecasts prior to the actual event, in order to estimate the arrival time of main lahar pulses, usually characterized by block-rich fronts, which are responsible for most of the damage to infrastructure and loss of goods and lives

ES cells-derived ectomesenchymal cells for tooth engineering.

Recent progresses in stem cell biology and tissue engineering allow considering the possible development of new therapies for compensating the dental tissue losses associated with traumas, pathologies or ageing. The possibility of generating a tooth by mimicking development through reassociations between dental epithelial cells and ectomesenchymal cells derived from the neural crest (NC) has been demonstrated in the mouse. In the search of cell sources to be used for a human transfer, pluripotent stem cells could represent a good alternative. Our study thus focuses on obtaining, ectomesenchymal cells from pluripotent ES cells, capable of promoting tooth histomorphogenesis, when reassociated with a competent dental epithelium. To this end, two ES differentiation protocols, using cyclopamine or a combination of FGF2 and BMP4, have been developed and tested for their capacity to generate such cells. The differentiated ES cells were characterized by quantitative RT-PCR. Both protocols led the cells to acquire in 10 days a mesenchymal-like cell morphology. Rapidly after induction, the cells loose their expression of pluripotent genes while sequentially activating typical NC specifiers. However, the kinetics of gene activation differed between the 2 protocols. Interestingly, Twist, a gene whose expression in the NC is associated with a commitment towards an ectomesenchymal fate, is only activated under the influence of FGF2 and BMP4. Reassociation experiments with a competent epithelium will allow testing the odontogenic potential of the differentiated ES cells. These experiments performed in the mouse system should allow defining a strategy for obtaining odontogenic competent human cells. Les progrès en matière de biologie de cellules souches et d’ingénierie tissulaire permettent d’envisager le développement de nouvelles thérapies pour pallier les pertes de tissus dentaires consécutives à des traumatismes, des situations pathologiques ou au vieillissement. La possibilité de générer une dent en mimant le développement, par réassociations entre cellules dentaires épithéliales et mésenchymateuses dérivées des crêtes neurales (CN), a été démontrée chez la souris. Dans la recherche de ressources cellulaires utilisables pour un transfert chez l’homme, les cellules souches pluripotentes pourraient constituer une alternative. Notre but est d’obtenir à partir de ces dernières, des cellules ectomésenchymateuses capables d’interagir avec un épithélium dentaire pour promouvoir l’histomorphogenèse d’une dent. Pour cela, deux protocoles de différenciation de cellules ES, utilisant la cyclopamine ou une combinaison de FGF2/BMP4, ont été mis au point. Les cellules induites ont été caractérisées par PCR quantitative. Les deux protocoles de différenciation amènent les cellules à acquérir en 10 jours, une morphologie de type mésenchymateux. Après induction, l’expression des gènes de pluripotence chute de façon drastique alors que celle des gènes spécificateurs de CN est activée. Toutefois, la cinétique varie selon le protocole. Le gène Twist, dont l’expression dans les CN est associée à un engagement vers l’ectomésenchyme, n’est activé significativement que sous l’action de FGF2/BMP4. Des expériences de réassociations avec un épithélium dentaire sont en cours pour évaluer le potentiel odontogène des cellules ES différenciées. A terme, ces approches menées chez la souris devraient permettre de définir une stratégie pour l’obtention de cellules compétentes humaines.Recent progresses in stem cell biology and tissue engineering allow considering the possible development of new therapies for compensating the dental tissue losses associated with traumas, pathologies or ageing. The possibility of generating a tooth by mimicking development through reassociations between dental epithelial cells and ectomesenchymal cells derived from the neural crest (NC) has been demonstrated in the mouse. In the search of cell sources to be used for a human transfer, pluripotent stem cells could represent a good alternative. Our study thus focuses on obtaining, ectomesenchymal cells from pluripotent ES cells, capable of promoting tooth histomorphogenesis, when reassociated with a competent dental epithelium. To this end, two ES differentiation protocols, using cyclopamine or a combination of FGF2 and BMP4, have been developed and tested for their capacity to generate such cells. The differentiated ES cells were characterized by quantitative RT-PCR. Both protocols led the cells to acquire in 10 days a mesenchymal-like cell morphology. Rapidly after induction, the cells loose their expression of pluripotent genes while sequentially activating typical NC specifiers. However, the kinetics of gene activation differed between the 2 protocols. Interestingly, Twist, a gene whose expression in the NC is associated with a commitment towards an ectomesenchymal fate, is only activated under the influence of FGF2 and BMP4. Reassociation experiments with a competent epithelium will allow testing the odontogenic potential of the differentiated ES cells. These experiments performed in the mouse system should allow defining a strategy for obtaining odontogenic competent human cells. Les progrès en matière de biologie de cellules souches et d’ingénierie tissulaire permettent d’envisager le développement de nouvelles thérapies pour pallier les pertes de tissus dentaires consécutives à des traumatismes, des situations pathologiques ou au vieillissement. La possibilité de générer une dent en mimant le développement, par réassociations entre cellules dentaires épithéliales et mésenchymateuses dérivées des crêtes neurales (CN), a été démontrée chez la souris. Dans la recherche de ressources cellulaires utilisables pour un transfert chez l’homme, les cellules souches pluripotentes pourraient constituer une alternative. Notre but est d’obtenir à partir de ces dernières, des cellules ectomésenchymateuses capables d’interagir avec un épithélium dentaire pour promouvoir l’histomorphogenèse d’une dent. Pour cela, deux protocoles de différenciation de cellules ES, utilisant la cyclopamine ou une combinaison de FGF2/BMP4, ont été mis au point. Les cellules induites ont été caractérisées par PCR quantitative. Les deux protocoles de différenciation amènent les cellules à acquérir en 10 jours, une morphologie de type mésenchymateux. Après induction, l’expression des gènes de pluripotence chute de façon drastique alors que celle des gènes spécificateurs de CN est activée. Toutefois, la cinétique varie selon le protocole. Le gène Twist, dont l’expression dans les CN est associée à un engagement vers l’ectomésenchyme, n’est activé significativement que sous l’action de FGF2/BMP4. Des expériences de réassociations avec un épithélium dentaire sont en cours pour évaluer le potentiel odontogène des cellules ES différenciées. A terme, ces approches menées chez la souris devraient permettre de définir une stratégie pour l’obtention de cellules compétentes humaines

Magnetoresistance Anomalies in (Ga,Mn)As Epilayers with Perpendicular Magnetic Anisotropy

We report the observation of anomalies in the longitudinal magnetoresistance of tensile-strained (Ga,Mn)As epilayers with perpendicular magnetic anisotropy. Magnetoresistance measurements carried out in the planar geometry (magnetic field parallel to the current density) reveal "spikes" that are antisymmetric with respect to the direction of the magnetic field. These anomalies always occur during magnetization reversal, as indicated by a simultaneous change in sign of the anomalous Hall effect. The data suggest that the antisymmetric anomalies originate in anomalous Hall effect contributions to the longitudinal resistance when domain walls are located between the voltage probes. This interpretation is reinforced by carrying out angular sweeps of $\vec{H}$, revealing an antisymmetric dependence on the helicity of the field sweep.Comment: Submitted to Phys. Rev.