Laser tweezers for atomic solitons

We describe a controllable and precise laser tweezers for Bose-Einstein condensates of ultracold atomic gases. In our configuration, a laser beam is used to locally modify the sign of the scattering length in the vicinity of a trapped BEC. The induced attractive interactions between atoms allow to extract and transport a controllable number of atoms. We analyze, through numerical simulations, the number of emitted atoms as a function of the width and intensity of the outcoupling beam. We also study different configurations of our system, as the use of moving beams. The main advantage of using the control laser beam to modify the nonlinear interactions in comparison to the usual way of inducing optical forces, i.e. through linear trapping potentials, is to improve the controllability of the outcoupled solitary wave-packet, which opens new possibilities for engineering macroscopic quantum states.Comment: 6 pages, 7 figure

Kinetics of occupancy of defect states in poly(3-hexylthiophene): fullerene solar cells

Energetics and kinetics of defects in the effective band gap of organic bulk heterojunctions are determined by means of capacitance methods. The technique consists of calculating the junction capacitance derivative with respect to the angular frequency of the small voltage perturbation applied to thin film poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester solar cells, varying the temperature. The analysis reveals the presence of defect bands (shallow acceptors) centered at E0 = 35 meV above the highest-occupied molecular orbital level of P3HT. The total density of defects results of order 1016 cm− 3. Characteristic frequency is obtained to be situated within the range of 1–10 Hz. Defect bands acting as negatively charged levels are responsible for the p-doping of the active layer and the band-bending near the cathode contact, as derived from Mott–Schottky capacitance–voltage analysis

Correction: Assessment of angle velocity in girls with adolescent idiopathic scoliosis

Correction to Escalada F, Marco E, Duarte E, Muniesa JM, Boza R, Tejero M, Cáceres E. Assessment of angle velocity in girls with adolescent idiopathic scoliosis. Scoliosis 2009; 4:20

Nonautonomous "rogons" in the inhomogeneous nonlinear Schrodinger equation with variable coefficients

The analytical nonautonomous rogons are reported for the inhomogeneous nonlinear Schr\"odinger equation with variable coefficients in terms of rational-like functions by using the similarity transformation and direct ansatz. These obtained solutions can be used to describe the possible formation mechanisms for optical, oceanic, and matter rogue wave phenomenon in optical fibres, the deep ocean, and Bose-Einstein condensates, respectively. Moreover, the snake propagation traces and the fascinating interactions of two nonautonomous rogons are generated for the chosen different parameters. The obtained nonautonomous rogons may excite the possibility of relative experiments and potential applications for the rogue wave phenomenon in the field of nonlinear science.Comment: 11 pages, 6 figure

Transcriptionally active HERV-H retrotransposons demarcate topologically associating domains in human pluripotent stem cells.

Chromatin architecture has been implicated in cell type-specific gene regulatory programs, yet how chromatin remodels during development remains to be fully elucidated. Here, by interrogating chromatin reorganization during human pluripotent stem cell (hPSC) differentiation, we discover a role for the primate-specific endogenous retrotransposon human endogenous retrovirus subfamily H (HERV-H) in creating topologically associating domains (TADs) in hPSCs. Deleting these HERV-H elements eliminates their corresponding TAD boundaries and reduces the transcription of upstream genes, while de novo insertion of HERV-H elements can introduce new TAD boundaries. The ability of HERV-H to create TAD boundaries depends on high transcription, as transcriptional repression of HERV-H elements prevents the formation of boundaries. This ability is not limited to hPSCs, as these actively transcribed HERV-H elements and their corresponding TAD boundaries also appear in pluripotent stem cells from other hominids but not in more distantly related species lacking HERV-H elements. Overall, our results provide direct evidence for retrotransposons in actively shaping cell type- and species-specific chromatin architecture

El GEOCAMP : un sitio web y una herramienta de edición para las actividades de campo en Geología

El GEOCAMP es un portal informático de apoyo a las actividades de campo en Geología. Es un sitio web de libre acceso a disposición de docentes y estudiantes que realizan prácticas de campo como parte de sus enseñanzas o aprendizajes. Es un espacio hipermedia que contiene materiales didácticos de producción propia y numerosos enlaces a todo tipo de informaciones relacionadas con las prácticas de campo en asignaturas de Ciencias de la Tierra. El portal incorpora una herramienta de autoedición - el GEOCAMP-EDITOR -, una aplicación informática que permite introducir desde cualquier lugar del mundo los textos y figuras que conforman la descripción de un punto o itinerario de interés geológico. A partir de la información proporcionada, se genera un documento con una maquetación propia que puede ser consultado en formato HTML o descargado como PDF y utilizado como guía de campo.GEOCAMP is a website devoted to field activities in Geology. It is a free access web site available for both teachers and students who carry out field exercises as part of their teaching or learning. It is a hypermedia resource containing original teaching materials and several links with all kind of topics related to field exercises in subjects of Earth Sciences. The website includes a desktop publishing tool - the GEOCAMP-EDITOR -, a software application that allows to download from anywhere in the world the text and images that describe a point or route of geological interest. Once the information has been downloaded, a document is automatically generated. This document can be accessed in HTML format or downloaded as a PDF document to be used as a field guide

PIP5KIβ Selectively Modulates Apical Endocytosis in Polarized Renal Epithelial Cells

Localized synthesis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] at clathrin coated pits (CCPs) is crucial for the recruitment of adaptors and other components of the internalization machinery, as well as for regulating actin dynamics during endocytosis. PtdIns(4,5)P2 is synthesized from phosphatidylinositol 4-phosphate by any of three phosphatidylinositol 5-kinase type I (PIP5KI) isoforms (α, β or γ). PIP5KIβ localizes almost exclusively to the apical surface in polarized mouse cortical collecting duct cells, whereas the other isoforms have a less polarized membrane distribution. We therefore investigated the role of PIP5KI isoforms in endocytosis at the apical and basolateral domains. Endocytosis at the apical surface is known to occur more slowly than at the basolateral surface. Apical endocytosis was selectively stimulated by overexpression of PIP5KIβ whereas the other isoforms had no effect on either apical or basolateral internalization. We found no difference in the affinity for PtdIns(4,5)P2-containing liposomes of the PtdIns(4,5)P2 binding domains of epsin and Dab2, consistent with a generic effect of elevated PtdIns(4,5)P2 on apical endocytosis. Additionally, using apical total internal reflection fluorescence imaging and electron microscopy we found that cells overexpressing PIP5KIβ have fewer apical CCPs but more internalized coated structures than control cells, consistent with enhanced maturation of apical CCPs. Together, our results suggest that synthesis of PtdIns(4,5)P2 mediated by PIP5KIβ is rate limiting for apical but not basolateral endocytosis in polarized kidney cells. PtdIns(4,5)P2 may be required to overcome specific structural constraints that limit the efficiency of apical endocytosis. © 2013 Szalinski et al

Investigation of pre-existing and generated defects in non-filamentary a-Si/TiO2 RRAM and their impacts on RTN amplitude distribution

An extensive investigation of the pre-existing and generated defects in amorphous-Si/TiO2 based non-filamentary (a-VMCO) RRAM device has been carried out in this work to identify the switching and degradation mechanisms, through a combination of random-telegraph-noise (RTN) and constant- voltage-stress (CVS) analysis. The amplitude of RTN, which leads to read instability, is also evaluated statistically at different stages of cell degradation and correlated with different defects, for the first time. It is found that the switching between low and high resistance states (LRS and HRS) are correlated with the profile modulation of pre-existing defects in the ‘defect-less’ region near the a-Si/TiO2 interface. The RTN amplitude observed at this stage is small and has a tight distribution. At longer stress times, a percolation path is formed due to defects generation, which introduces larger RTN amplitude and a significant tail in its distribution