191 research outputs found
Disorder Effects on Exciton-Polariton Condensates
The impact of a random disorder potential on the dynamical properties of Bose
Einstein condensates is a very wide research field. In microcavities, these
studies are even more crucial than in the condensates of cold atoms, since
random disorder is naturally present in the semiconductor structures. In this
chapter, we consider a stable condensate, defined by a chemical potential,
propagating in a random disorder potential, like a liquid flowing through a
capillary. We analyze the interplay between the kinetic energy, the
localization energy, and the interaction between particles in 1D and 2D
polariton condensates. The finite life time of polaritons is taken into account
as well. In the first part, we remind the results of [G. Malpuech et al. Phys.
Rev. Lett. 98, 206402 (2007).] where we considered the case of a static
condensate. In that case, the condensate forms either a glassy insulating phase
at low polariton density (strong localization), or a superfluid phase above the
percolation threshold. We also show the calculation of the first order spatial
coherence of the condensate versus the condensate density. In the second part,
we consider the case of a propagating non-interacting condensate which is
always localized because of Anderson localization. The localization length is
calculated in the Born approximation. The impact of the finite polariton life
time is taken into account as well. In the last section we consider the case of
a propagating interacting condensate where the three regimes of strong
localization, Anderson localization, and superfluid behavior are accessible.
The localization length is calculated versus the system parameters. The
localization length is strongly modified with respect to the non-interacting
case. It is infinite in the superfluid regime whereas it is strongly reduced if
the fluid flows with a supersonic velocity.Comment: chapter for a book "Exciton Polaritons in Microcavities: New
Frontiers" by Springer (2012), the original publication is available at
http://www.springerlink.co
Finite Fault Analysis and Near Field Dynamic Strains and Rotations due to the 11/05/2011 (Mw5.2) Lorca Earthquake, South-Eastern Spain
The 11/5/2011 Lorca, Spain earthquake (Mw5.2) and related seismicity produced
extensive damage in the town of Lorca and vicinity. During these earthquakes,
evidence of rotations and permanent deformations in structures were observed.
To analyze these aspects and study the source properties from the near field,
the displacement time histories were obtained including the static component at
Lorca station. Displacement time histories were computed by an appropriate
double time integration procedure of accelerograms. Using these data, the
foreshock and mainshock slip distributions were calculated by means of a
complete waveform kinematic inversion. To study the dynamic deformations, the
3D tensor of displacement gradients at Lorca station was first estimated by a
single station method. Using the finite fault inversion results and by means of
a first order finite difference approach, the dynamic deformations tensor at
surface was calculated at the recording site. In order to estimate the
distribution of the peak dynamic deformations, the calculation was extended to
the close neighboring area of the town. The possible influence of the
near-field deformations on the surface structures was analyzed.Comment: 29 pages, 8 figure
Validation of a Cost-Efficient Multi-Purpose SNP Panel for Disease Based Research
BACKGROUND: Here we present convergent methodologies using theoretical calculations, empirical assessment on in-house and publicly available datasets as well as in silico simulations, that validate a panel of SNPs for a variety of necessary tasks in human genetics disease research before resources are committed to larger-scale genotyping studies on those samples. While large-scale well-funded human genetic studies routinely have up to a million SNP genotypes, samples in a human genetics laboratory that are not yet part of such studies may be productively utilized in pilot projects or as part of targeted follow-up work though such smaller scale applications require at least some genome-wide genotype data for quality control purposes such as DNA "barcoding" to detect swaps or contamination issues, determining familial relationships between samples and correcting biases due to population effects such as population stratification in pilot studies. PRINCIPAL FINDINGS: Empirical performance in classification of relative types for any two given DNA samples (e.g., full siblings, parental, etc) indicated that for outbred populations the panel performs sufficiently to classify relationship in extended families and therefore also for smaller structures such as trios and for twin zygosity testing. Additionally, familial relationships do not significantly diminish the (mean match) probability of sharing SNP genotypes in pedigrees, further indicating the uniqueness of the "barcode." Simulation using these SNPs for an African American case-control disease association study demonstrated that population stratification, even in complex admixed samples, can be adequately corrected under a range of disease models using the SNP panel. CONCLUSION: The panel has been validated for use in a variety of human disease genetics research tasks including sample barcoding, relationship verification, population substructure detection and statistical correction. Given the ease of genotyping our specific assay contained herein, this panel represents a useful and economical panel for human geneticists
Developing Students’ Communication in Technical English with Project Based Learning Methodology
Technical communication is an extremely important soft skill for civil engineers at the
workplace. Due to globalization trends this technical communication often should be
performed in English. If we join the fact that undergraduate engineering programs in Spain
have been taught exclusively in Spanish, with which in addition, in rare cases those
programs provide intentionally placed discipline-specific technical communication
experiences, this all amounts to a major problem, regarded as an obstacle that limit
undergraduates’ opportunities to work abroad. Aware of this problem, some schools
provide their students with a brief course on “Technical English”. However, this course does
not cover all the skills that the student would need in the labour market, such as speaking
and listening abilities.
This paper promotes an innovative teaching methodology that allows Spanish Civil
Engineering students to hone English communication skills through “Lunch&Movies”
sessions. In each session a documentary about technical Civil Engineering topics is shown.
After the screening, students work in small inter-cohort groups with a guiding lecturer.
These groups debate on different questions related to the video, encouraging participation,
and fostering their self-confidence to talk about technical English topics in public. Different
surveys were developed to demonstrate the students’ interest in learning technical English,
and to evaluate the benefit for the attendees and their achievements. The results show that
the students are conscious of the importance of technical English for their future careers,
and most of them improved their initial level as the sessions progressed and they gained
confidence in the foreign language. Also, through a pilot subject in English, it was
demonstrated that the participants of the “Lunch&Movies” sessions obtained better oral
qualifications than those who did not participate. In fact, the overall results indicated that
Lunch & Movie sessions can improve students' technical oral skills as well as their own
perceptions of their abilities
A systematic review of cerebral microdialysis and outcomes in TBI: relationships to patient functional outcome, neurophysiologic measures, and tissue outcome
OBJECTIVE: To perform a systematic review on commonly measured cerebral microdialysis (CMD) analytes and their association to: (A) patient functional outcome, (B) neurophysiologic measures, and (C) tissue outcome; after moderate/severe TBI. The aim was to provide a foundation for next-generation CMD studies and build on existing pragmatic expert guidelines for CMD. METHODS: We searched MEDLINE, BIOSIS, EMBASE, Global Health, Scopus, Cochrane Library (inception to October 2016). Strength of evidence was adjudicated using GRADE. RESULTS: (A) Functional Outcome: 55 articles were included, assessing outcome as mortality or Glasgow Outcome Scale (GOS) at 3-6 months post-injury. Overall, there is GRADE C evidence to support an association between CMD glucose, glutamate, glycerol, lactate, and LPR to patient outcome at 3-6 months. (B) Neurophysiologic Measures: 59 articles were included. Overall, there currently exists GRADE C level of evidence supporting an association between elevated CMD measured mean LPR, glutamate and glycerol with elevated ICP and/or decreased CPP. In addition, there currently exists GRADE C evidence to support an association between elevated mean lactate:pyruvate ratio (LPR) and low PbtO2. Remaining CMD measures and physiologic outcomes displayed GRADE D or no evidence to support a relationship. (C) Tissue Outcome: four studies were included. Given the conflicting literature, the only conclusion that can be drawn is acute/subacute phase elevation of CMD measured LPR is associated with frontal lobe atrophy at 6 months. CONCLUSIONS: This systematic review replicates previously documented relationships between CMD and various outcome, which have driven clinical application of the technique. Evidence assessments do not address the application of CMD for exploring pathophysiology or titrating therapy in individual patients, and do not account for the modulatory effect of therapy on outcome, triggered at different CMD thresholds in individual centers. Our findings support clinical application of CMD and refinement of existing guidelines
Development of a Panel of Genome-Wide Ancestry Informative Markers to Study Admixture Throughout the Americas
Most individuals throughout the Americas are admixed descendants of Native American, European, and African ancestors. Complex historical factors have resulted in varying proportions of ancestral contributions between individuals within and among ethnic groups. We developed a panel of 446 ancestry informative markers (AIMs) optimized to estimate ancestral proportions in individuals and populations throughout Latin America. We used genome-wide data from 953 individuals from diverse African, European, and Native American populations to select AIMs optimized for each of the three main continental populations that form the basis of modern Latin American populations. We selected markers on the basis of locus-specific branch length to be informative, well distributed throughout the genome, capable of being genotyped on widely available commercial platforms, and applicable throughout the Americas by minimizing within-continent heterogeneity. We then validated the panel in samples from four admixed populations by comparing ancestry estimates based on the AIMs panel to estimates based on genome-wide association study (GWAS) data. The panel provided balanced discriminatory power among the three ancestral populations and accurate estimates of individual ancestry proportions (R2>0.9 for ancestral components with significant between-subject variance). Finally, we genotyped samples from 18 populations from Latin America using the AIMs panel and estimated variability in ancestry within and between these populations. This panel and its reference genotype information will be useful resources to explore population history of admixture in Latin America and to correct for the potential effects of population stratification in admixed samples in the region
Rate and duration of hospitalisation for acute pulmonary embolism in the real-world clinical practice of different countries : Analysis from the RIETE registry
publishersversionPeer reviewe
Detection of Alpha-Rod Protein Repeats Using a Neural Network and Application to Huntingtin
A growing number of solved protein structures display an elongated structural
domain, denoted here as alpha-rod, composed of stacked pairs of anti-parallel
alpha-helices. Alpha-rods are flexible and expose a large surface, which makes
them suitable for protein interaction. Although most likely originating by
tandem duplication of a two-helix unit, their detection using sequence
similarity between repeats is poor. Here, we show that alpha-rod repeats can be
detected using a neural network. The network detects more repeats than are
identified by domain databases using multiple profiles, with a low level of
false positives (<10%). We identify alpha-rod repeats in
approximately 0.4% of proteins in eukaryotic genomes. We then
investigate the results for all human proteins, identifying alpha-rod repeats
for the first time in six protein families, including proteins STAG1-3, SERAC1,
and PSMD1-2 & 5. We also characterize a short version of these repeats
in eight protein families of Archaeal, Bacterial, and Fungal species. Finally,
we demonstrate the utility of these predictions in directing experimental work
to demarcate three alpha-rods in huntingtin, a protein mutated in
Huntington's disease. Using yeast two hybrid analysis and an
immunoprecipitation technique, we show that the huntingtin fragments containing
alpha-rods associate with each other. This is the first definition of domains in
huntingtin and the first validation of predicted interactions between fragments
of huntingtin, which sets up directions toward functional characterization of
this protein. An implementation of the repeat detection algorithm is available
as a Web server with a simple graphical output: http://www.ogic.ca/projects/ard. This can be further visualized
using BiasViz, a graphic tool for representation of multiple sequence
alignments
How do 66 European institutional review boards approve one protocol for an international prospective observational study on traumatic brain injury? Experiences from the CENTER-TBI study
Background The European Union (EU) aims to optimize patient protection and efficiency of health-care research by harmonizing procedures across Member States. Nonetheless, further improvements are required to increase multicenter research efficiency. We investigated IRB procedures in a large prospective European multicenter study on traumatic brain injury (TBI), aiming to inform and stimulate initiatives to improve efficiency. Methods We reviewed relevant documents regarding IRB submission and IRB approval from European neurotrauma centers participating in the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI). Documents included detailed information on IRB procedures and the duration from IRB submission until approval(s). They were translated and analyzed to determine the level of harmonization of IRB procedures within Europe. Results From 18 countries, 66 centers provided the requested documents. The primary IRB review was conducted centrally (N = 11, 61%) or locally (N = 7, 39%) and primary IRB approval was obtained after one (N = 8, 44%), two (N = 6, 33%) or three (N = 4, 23%) review rounds with a median duration of respectively 50 and 98 days until primary IRB approval. Additional IRB approval was required in 55% of countries and could increase duration to 535 days. Total duration from submission until required IRB approval was obtained was 114 days (IQR 75-224) and appeared to be shorter after submission to local IRBs compared to central IRBs (50 vs. 138 days, p = 0.0074). Conclusion We found variation in IRB procedures between and within European countries. There were differences in submission and approval requirements, number of review rounds and total duration. Research collaborations could benefit from the implementation of more uniform legislation and regulation while acknowledging local cultural habits and moral values between countries.Peer reviewe
First results of the140ce(N,ү)141ce cross-section measurement at n_tof
An accurate measurement of the140Ce(n,ү) energy-dependent cross-section was performed at the n_TOF facility at CERN. This cross-section is of great importance because it represents a bottleneck for the s-process nucleosynthesis and determines to a large extent the cerium abundance in stars. The measurement was motivated by the significant difference between the cerium abundance measured in globular clusters and the value predicted by theoretical stellar models. This discrepancy can be ascribed to an overestimation of the140Ce capture cross-section due to a lack of accurate nuclear data. For this measurement, we used a sample of cerium oxide enriched in140Ce to 99.4%. The experimental apparatus consisted of four deuterated benzene liquid scintillator detectors, which allowed us to overcome the difficulties present in the previous measurements, thanks to their very low neutron sensitivity. The accurate analysis of the p-wave resonances and the calculation of their average parameters are fundamental to improve the evaluation of the140Ce Maxwellian-averaged cross-section
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