Higher-order Van Hove singularity in magic-angle twisted trilayer graphene

Twisted trilayer graphene (TTG) has recently emerged experimentally as a fascinating playground to study correlated and exotic superconducting phases. We have found that TTG hosts a zero-energy higher-order Van Hove singularity with an exponent −1/3 that is stronger than the one predicted in twisted bilayer graphene. This singularity is protected by a threefold rotation symmetry and a combined mirror-particle-hole symmetry and can be tuned with only the twist angle and a perpendicular electric field. It arises from the combined merging of Van Hove singularities and Dirac cones at zero energy, a scheme that goes beyond the recent classifications of Van Hove singularities in single-band models. This structure gives a topological Lifshitz transition, with anomalous exponent −2/5, which can be achieved in TTG by varying a third control parameter such as the atomic corrugation. The interplay between the nonstandard class of higher-order Van Hove singularities and interaction effects offers an unprecedented platform for studying correlation and superconductivity

Vertical finger displacement is reduced in index finger tapping during repeated bout rate enhancement

The present study analyzed (a) whether a recently reported phenomenon of repeated bout rate enhancement in finger tapping (i.e., a cumulating increase in freely chosen finger tapping frequency following submaximal muscle activation in the form of externally unloaded voluntary tapping) could be replicated and (b) the hypotheses that the faster tapping was accompanied by changed vertical displacement of the fingertip and changed peak force during tapping. Right-handed, healthy, and recreationally active individuals (n = 24) performed two 3-min index finger tapping bouts at freely chosen tapping frequency, separated by 10-min rest. The recently reported phenomenon of repeated bout rate enhancement was replicated. The faster tapping (8.8 ± 18.7 taps/min, corresponding to 6.0 ± 11.0%, p = .033) was accompanied by reduced vertical displacement (1.6 ± 2.9 mm, corresponding to 6.3 ± 14.9%, p = .012) of the fingertip. Concurrently, peak force was unchanged. The present study points at separate control mechanisms governing kinematics and kinetics during finger tapping.</jats:p

Were they engraved? Cave art taphonomy in the Lesser Antilles - Working hypotheses

Here we present the working hypotheses of a project dedicated to the taphonomy of cave rock art in the Lesser Antilles, based on results provided by the preliminary study of two Amerindian-occupied caves in Marie-Galante, FWI. In the caves of Guadeloupe, it is sometimes possible to observe wall morphologies that resemble pre-Columbian petroglyphs, but without engraved lines. The question arises then whether these morphologies are engraved pictures. Blanchard Cave (S coast of Marie-Galante), contains such wall morphologies that can be thought to represent weathered petroglyphs, especially when considering the pre-Columbian burials preserved in the cave entrance. The study of physical processes acting in the site provides an understanding of mechanisms that could have caused the engravings' disappearance. Site microclimatology, assessed by hygrometric and thermic measurements, reveals an unstable regime due to air currents that bring cold air deep into the cave. The result is a limited hygrometry and, above all, a transport of sea spray. The marine aerosol inputs highlight the occurrence of salt and gypsum minerals on the walls that trigger salt weathering of the rock. The resulting sediment is typically loose, very light tan silt that accumulates on the cave floor. Test pits were used to characterize and to date sediments deposited in the cave. Taking into account the rate of accumulation of sediments produced by weathering allows estimates of mean wall weathering of up to 0.6 cm/century. Such a rate would explain the alteration and even the disappearance of Amerindian carvings that are several centuries old. The questionable morphologies observed in Blanchard Cave have been compared to the Pre-Columbian petroglyphs preserved in the nearby cave of Morne Rita through photogrammetric recording. This comparison shows that the wall morphologies observed in the first site have a size and shape that fall into the variability of Pre-Columbian artworks, although they are characterized by a blurred surface and an enlargement of the outline and the cupules ascribable to the wall alteration by salt weathering. Based on these observations, it can be hypothesized that the Blanchard cave is a degraded petroglyph site. These preliminary results also help to identify the factors leading to certain types of degradation (size, morphology, nature of the rock and location). Considering that such factors are common in Lesser Antilles caves, a more general theory can be proposed that a number of engraved caves of the Lesser Antilles have not been identified as such. These hypotheses, if proven true, have two important implications for the interpretation of the pre-Columbian decorated caves distribution: 1) an under-representation of the number of known sites and 2) a bias, in the preserved sites, favoring "wet" caves where salt weathering of the cave walls does not occur.Aquí presentamos la hipótesis de trabajo de un proyecto dedicado a la tafonomía de arte de cuevas en las Antillas Menores, basada en el estudio preliminar de dos cuevas en Marie-Galante, FWI, ocupadas por amerindios. En las cuevas de Guadeloupe, a veces se puede observar morfologías de la pared que parecen indicar la presencia de petroglifos precolombinos, pero no dejan reconocer líneas grabadas. La pregunta es si realmente se trata de creaciones humanas. La cueva de Blanchard (costa sur de Marie-Galante) muestra este fenómeno, hacemos notar que en este sitio también existen tumbas precolombinas. El estudio de los procesos físicos que actúan en el sitio provee un entendimiento de los mecanismos que podrían haber causado la desaparición de los grabados. La microclimatología del sitio, evaluada por medidas higrométricas y térmicas, revela un régimen inestable debido al corriente de aire que trae aire frío al interior de la cueva. El resultado es una higrometría limitada y, sobre todo, el ingreso de rociada de agua del mar. El efecto de "aerosol marino" favorece la ocurrencia de sal y minerales de yeso en la pared que resulta en un desgaste por sales y un sedimento suelto de color claro que acumula en el suelo de la cueva. Se excavaron sondeos para caracterizar y datar los sedimentos depositados en la cueva. Tomando en cuenta el grado de acumulación producido por el desgaste permite estimaciones del desgaste de pared de hasta 0,6 cm / siglo. Esto podría explicar la alteración y aún la desaparición de grabados amerindios que tienen una antigüedad de varios centenares de años. Comparamos loas morfologías en cuestión de la cueva de Blanchard a petroglifos precolombinos preservados en la cueva cercana de Morne Rita a través de la documentación fotogramétrica. Esta comparación muestra que las morfologías de la pared en el primer sitio tiene un tamaño y una forma que caen dentro de la variabilidad de arte precolombino aunque se caracterizan por una superficie borrosa y un tamaño mayor del contorno y depresiones que pueden ser adscritos a los efectos de desgaste por sal. Basado en estas observaciones, sugerimos que la cueva de Blanchard es un sitio de petroglifos erosionados. Estos resultados preliminares pueden ayudar a identificar los factores que conducen a ciertos tipos de erosión (tamaño, morfología, naturaleza de la roca y ubicación). Considerando que estos factores son corrientes en las cuevas de las Antillas Menores, proponemos que una cantidad de cuevas con grabados no fueron identificadas como tales. Si esta hipótesis puede ser comprobada, hay dos implicancias importantes para la distribución de cuevas decoradas precolombinas: 1- una sub-representación de la cantidad de sitios conocidas y 2- un prejuicio en los sitios preservados, ya que se favorecen cuevas "húmedas" donde el desgaste por sales no ocurre

In Vitro versus in Mice: Efficacy and Safety of Decoquinate and Quinoline-O-Carbamate Derivatives against Experimental Infection with Neospora caninum Tachyzoites.

The effects of decoquinate (DCQ) and three O-quinoline-carbamate-derivatives were investigated using human foreskin fibroblasts (HFF) infected with Neospora caninum tachyzoites. These compounds exhibited half-maximal proliferation inhibition (IC50s) from 1.7 (RMB060) to 60 nM (RMB055). Conversely, when applied at 5 (DCQ, RMB054) or 10µM (RMB055, RMB060), HFF viability was not affected. Treatments of infected cell cultures at 0.5µM altered the ultrastructure of the parasite mitochondrion and cytoplasm within 24 h, most pronounced for RMB060, and DCQ, RMB054 and RMB060 did not impair the viability of splenocytes from naïve mice. Long-term treatments of N. caninum-infected HFF monolayers with 0.5µM of each compound showed that only exposure to RMB060 over a period of six consecutive days had a parasiticidal effect, while the other compounds were not able to kill all tachyzoites in vitro. Thus, DCQ and RMB060 were comparatively assessed in the pregnant neosporosis mouse model. The oral application of these compounds suspended in corn oil at 10 mg/kg/day for 5 d resulted in a decreased fertility rate and litter size in the DCQ group, whereas reproductive parameters were not altered by RMB060 treatment. However, both compounds failed to protect mice from cerebral infection and did not prevent vertical transmission/pup mortality. Thus, despite the promising in vitro efficacy and safety characteristics of DCQ and DCQ-derivatives, proof of concept for activity against neosporosis could not be demonstrated in the murine model

Hydrobia ulvae imposex levels at Ria de Aveiro (NW Portugal) between 1998 and 2007: a counter-current bioindicator?

Imposex expression in prosobranch gastropods has been widely used as a biomarker of tributyltin (TBT) pollution. Estuaries have been described as the most affected areas by this problem since they usually enclose the main TBT sources—ports, dockyards and marinas—resulting from the compound’s application as a biocide in antifouling paints on ships. Using Hydrobia ulvae as a bioindicator, the current work addresses the most reliable methods to reduce the influence of critical variables, such as the animals’ size, on imposex levels assessment for TBT pollution monitoring and presents its temporal trends from 1998 to 2007 in Ria de Aveiro (NW Portugal) to evaluate the effectiveness of recent legislation applied to reduce TBT environmental levels. H. ulvae imposex levels did not decrease in this estuarine system during the last decade despite the implementation of the EU Regulation No. 782/2003. Instead, there was a global significant increase in the percentage of females affected by imposex and a slight increase of the vas deferens sequence index (VDSI), contrasting with what has been described for other bioindicators in the same study area. These results show that different biology/ecology traits determine distinct routes of TBT uptake and/or bioaccumulation, pointing the importance of choosing the bioindicator depending on the compartment that is being monitored (sediment vs. water). Sediment ingestion as feeding habit is discussed and pointed as a reason to choose H. ulvae as a bioindicator of TBT pollution persistence in sediment. It is therefore predicted that the response of different prosobranch species around the world may diverge according to the compartment that is being monitored and that female masculinisation may not be completely eradicated in the near future due to TBT persistence in sediments

Vocabulaire 3D - Lexique pour les Sciences Humaines et Sociales

Ce document est le résultat d’un effort continu pour permettre aux acteurs des SHS et ceux de la 3D d’interagir autour d’un vocabulaire commun. Ce lexique a pour but d’accompagner les différents livrables du consortium 3D. Il a aussi vocation à terme à aider à l’enrichissement de TaDiRAH , « Taxonomy of Digital Research Activities in the Humani-ties » du consortium européen DARIAH . Ce processus continu est illustré par le fait que ce document en est à sa deuxième versionCe document est le résultat d’un effort continu pour permettre aux acteurs des SHS et ceux de la 3D d’interagir autour d’un vocabulaire commun. Ce lexique a pour but d’accompagner les différents livrables du consortium 3D. Il a aussi vocation à terme à aider à l’enrichissement de TaDiRAH , « Taxonomy of Digital Research Activities in the Humani-ties » du consortium européen DARIAH . Ce processus continu est illustré par le fait que ce document en est à sa deuxième versio