1,414 research outputs found
Modelling avalanches in martensites
Solids subject to continuous changes of temperature or mechanical load often
exhibit discontinuous avalanche-like responses. For instance, avalanche
dynamics have been observed during plastic deformation, fracture, domain
switching in ferroic materials or martensitic transformations. The statistical
analysis of avalanches reveals a very complex scenario with a distinctive lack
of characteristic scales. Much effort has been devoted in the last decades to
understand the origin and ubiquity of scale-free behaviour in solids and many
other systems. This chapter reviews some efforts to understand the
characteristics of avalanches in martensites through mathematical modelling.Comment: Chapter in the book "Avalanches in Functional Materials and
Geophysics", edited by E. K. H. Salje, A. Saxena, and A. Planes. The final
publication is available at Springer via
http://dx.doi.org/10.1007/978-3-319-45612-6_
PenetraciĂłn de fosfomicina en explantes intestinales
Fosfomycin (FOS) is an antibiotic used in pig farms for treatment and prevention of infections caused by resistant bacteria during post-weaning period. Antibiotics and non-toxic concentrations of such mycotoxins as deoxynivalenol (DON) are frequently found in the diet of animals. These compounds can establish interactions in the intestinal tract which affect and/or modify the penetration of FOS to enterocytes. The aim of this study was to culture intestinal explants from jejuna of pigs and to apply this model to the study of intracellular penetration of FOS in presence or absence of DON. The use of intestinal explants reduces the number of animals sacrificed per experiment and preserves normal intestinal histological structure in vitro. The results showed that there was no statistically significant difference in the intracellular concentration of FOS between explants incubated with 580 ppm FOS and explants incubated with 580 ppm FOS and 1 ppm DON. The Cmax was 12 ppm and the tmax was 2 h. Our study proved that only the 2% of the antibiotic is intracellularly accumulated and that the intracellular concentration of FOS is not affected by the presence of non-toxic concentrations of DON.Fosfomicina (FOS) es un antibiĂłtico utilizado en producciĂłn porcina para el tratamiento y prevenciĂłn de infecciones causadas por bacterias resistentes durante el post destete. En la dieta de los animales es frecuente encontrar antibiĂłticos y concentraciones subtĂłxicas de micotoxinas como el deoxinivalenol (DON). Estos compuestos pueden establecer interacciones en el tracto intestinal afectando y/o modificando la penetraciĂłn de FOS a los enterocitos. El objetivo de este trabajo fue desarrollar un cultivo de explantes de intestino procedentes de yeyuno de cerdos y aplicar este modelo para estudiar la penetraciĂłn intracelular de FOS en presencia o ausencia de DON. El uso de explantes intestinales disminuye el sacrificio de animales por experimento y preservan la estructura histolĂłgica intestinal normal en condiciones in vitro. Los resultados mostraron que no existieron diferencias estadĂsticamente significativas en la concentraciĂłn intracelular de FOS entre los explantes incubados con 580 ppm FOS y los explantes incubados con 580 ppm FOS y 1 ppm DON. Se obtuvo un Cmax de 12 ppm y tmax de 2 h. Nuestro estudio demostrĂł que solo el 2% del antibiĂłtico se acumula intracelularmente y que la concentraciĂłn intracelular de FOS no es afectada por la presencia de concentraciones subtĂłxicas de DON
Optical parametric oscillation with distributed feedback in cold atoms
There is currently a strong interest in mirrorless lasing systems, in which
the electromagnetic feedback is provided either by disorder (multiple
scattering in the gain medium) or by order (multiple Bragg reflection). These
mechanisms correspond, respectively, to random lasers and photonic crystal
lasers. The crossover regime between order and disorder, or correlated
disorder, has also been investigated with some success. Here, we report
one-dimensional photonic-crystal lasing (that is, distributed feedback lasing)
with a cold atom cloud that simultaneously provides both gain and feedback. The
atoms are trapped in a one-dimensional lattice, producing a density modulation
that creates a strong Bragg reflection with a small angle of incidence. Pumping
the atoms with auxiliary beams induces four-wave mixing, which provides
parametric gain. The combination of both ingredients generates a mirrorless
parametric oscillation with a conical output emission, the apex angle of which
is tunable with the lattice periodicity
A Standardised Procedure for Evaluating Creative Systems: Computational Creativity Evaluation Based on What it is to be Creative
Computational creativity is a flourishing research area, with a variety of creative systems being produced and developed. Creativity evaluation has not kept pace with system development with an evident lack of systematic evaluation of the creativity of these systems in the literature. This is partially due to difficulties in defining what it means for a computer to be creative; indeed, there is no consensus on this for human creativity, let alone its computational equivalent. This paper proposes a Standardised Procedure for Evaluating Creative Systems (SPECS). SPECS is a three-step process: stating what it means for a particular computational system to be creative, deriving and performing tests based on these statements. To assist this process, the paper offers a collection of key components of creativity, identified empirically from discussions of human and computational creativity. Using this approach, the SPECS methodology is demonstrated through a comparative case study evaluating computational creativity systems that improvise music
Plasmodium APC3 mediates chromosome condensation and cytokinesis during atypical mitosis in male gametogenesis
The anaphase promoting complex/cyclosome (APC/C) is a highly conserved multi-subunit E3 ubiquitin ligase that controls mitotic division in eukaryotic cells by tagging cell cycle regulators for proteolysis. APC3 is a key component that contributes to APC/C function. Plasmodium, the causative agent of malaria, undergoes atypical mitotic division during its life cycle. Only a small subset of APC/C components has been identified in Plasmodium and their involvement in atypical cell division is not well understood. Here, using reverse genetics we examined the localisation and function of APC3 in Plasmodium berghei. APC3 was observed as a single focus that co-localised with the centriolar plaque during asexual cell division in schizonts, whereas it appeared as multiple foci in male gametocytes. Functional studies using gene disruption and conditional knockdown revealed essential roles of APC3 during these mitotic stages with loss resulting in a lack of chromosome condensation, abnormal cytokinesis and absence of microgamete formation. Overall, our data suggest that Plasmodium utilises unique cell cycle machinery to coordinate various processes during ndomitosis, and this warrants further investigation in future studies
Accreting Protoplanets in the LkCa 15 Transition Disk
Exoplanet detections have revolutionized astronomy, offering new insights
into solar system architecture and planet demographics. While nearly 1900
exoplanets have now been discovered and confirmed, none are still in the
process of formation. Transition discs, protoplanetary disks with inner
clearings best explained by the influence of accreting planets, are natural
laboratories for the study of planet formation. Some transition discs show
evidence for the presence of young planets in the form of disc asymmetries or
infrared sources detected within their clearings, as in the case of LkCa 15.
Attempts to observe directly signatures of accretion onto protoplanets have
hitherto proven unsuccessful. Here we report adaptive optics observations of
LkCa 15 that probe within the disc clearing. With accurate source positions
over multiple epochs spanning 2009 - 2015, we infer the presence of multiple
companions on Keplerian orbits. We directly detect H{\alpha} emission from the
innermost companion, LkCa 15 b, evincing hot (~10,000 K) gas falling deep into
the potential well of an accreting protoplanet.Comment: 35 pages, 3 figures, 1 table, 9 extended data item
Personality, personnel selection, and job performance
Job Performance: The term job performance can
either refer to the objective or subjective outcomes
one achieves in a specific job (e.g., the profit of a
sales persons, the number of publications of a
scientist, the number of successful operations of
a surgeon) or to work-related activities (e.g., writing
an article, conducting specific surgical acts).
In the majority of research on this topic, job performance
as an outcome is used.
Personnel selection: Personnel selection
refers to the process of selecting the best
employees for specific jobs.
Introduction
One major application of personality research is in
the area of personnel selection. The key question
in this area is to which extent personality can
predict how well a candidate will perform on the
job he or she is applying for. Most scholars in this
area acknowledge that personality has predictive
validity for job performance. In line with this,
personality assessment is part of the selection
procedure in many organizations
Evaluation of dengue fever reports during an epidemic, Colombia
OBJECTIVE To assess the validity of dengue fever reports and how they relate to the definition of case and severity. METHODS Diagnostic test assessment was conducted using cross-sectional sampling from a universe of 13,873 patients treated during the fifth epidemiological period in health institutions from 11 Colombian departments in 2013. The test under analyses was the reporting to the National Public Health Surveillance System, and the reference standard was the review of histories identified by active institutional search. We reviewed all histories of patients diagnosed with dengue fever, as well as a random sample of patients with febrile syndromes. The specificity and sensitivity of reports were estimated for this purpose, considering the inverse of the probability of being selected for weighting. The concordance between reporting and the findings of the active institutional search was calculated using Kappa statistics. RESULTS We included 4,359 febrile patients, and 31.7% were classified as compatible with dengue fever (17 with severe dengue fever; 461 with dengue fever and warning signs; 904 with dengue fever and no warning signs). The global sensitivity of reports was 13.2% (95%CI 10.9;15.4) and specificity was 98.4% (95%CI 97.9;98.9). Sensitivity varied according to severity: 12.1% (95%CI 9.3;14.8) for patients presenting dengue fever with no warning signs; 14.5% (95%CI 10.6;18.4) for those presenting dengue fever with warning signs, and 40.0% (95%CI 9.6;70.4) for those with severe dengue fever. Concordance between reporting and the findings of the active institutional search resulted in a Kappa of 10.1%. CONCLUSIONS Low concordance was observed between reporting and the review of clinical histories, which was associated with the low reporting of dengue fever compatible cases, especially milder cases
Environmental variables, habitat discontinuity and life history shaping the genetic structure of Pomatoschistus marmoratus
Coastal lagoons are semi-isolated ecosystems
exposed to wide fluctuations of environmental conditions
and showing habitat fragmentation. These features may
play an important role in separating species into different
populations, even at small spatial scales. In this study, we
evaluate the concordance between mitochondrial (previous
published data) and nuclear data analyzing the genetic
variability of Pomatoschistus marmoratus in five localities,
inside and outside the Mar Menor coastal lagoon (SE
Spain) using eight microsatellites. High genetic diversity
and similar levels of allele richness were observed across
all loci and localities, although significant genic and
genotypic differentiation was found between populations
inside and outside the lagoon. In contrast to the FST values
obtained from previous mitochondrial DNA analyses
(control region), the microsatellite data exhibited significant
differentiation among samples inside the Mar Menor
and between lagoonal and marine samples. This pattern
was corroborated using Cavalli-Sforza genetic distances.
The habitat fragmentation inside the coastal lagoon and
among lagoon and marine localities could be acting as a
barrier to gene flow and contributing to the observed
genetic structure. Our results from generalized additive
models point a significant link between extreme lagoonal
environmental conditions (mainly maximum salinity) and
P. marmoratus genetic composition. Thereby, these environmental
features could be also acting on genetic structure
of coastal lagoon populations of P. marmoratus favoring
their genetic divergence. The mating strategy of P. marmoratus
could be also influencing our results obtained from
mitochondrial and nuclear DNA. Therefore, a special
consideration must be done in the selection of the DNA
markers depending on the reproductive strategy of the
species
Spanish validation of Bad Sobernheim Stress Questionnaire (BSSQ (brace).es) for adolescents with braces
<p>Abstract</p> <p>Background</p> <p>As a result of scientific and medical professionals gaining interest in Stress and Health Related Quality of Life (HRQL), the aim of our research is, thus, to validate into Spanish the German questionnaire <b>Bad Sobernheim Stress Questionnaire (BSSQ) (mit Korsett)</b>, for adolescents wearing braces.</p> <p>Methods</p> <p>The methodology used adheres to literature on trans-cultural adaptation by doing a translation and a back translation; it involved 35 adolescents, ages ranging between 10 and 16, with Adolescent Idiopathic Scoliosis (AIS) and wearing the same kind of brace (Rigo System ChĂȘneau Brace). The materials used were a socio-demographics data questionnaire, the SRS-22 and the Spanish version of BSSQ(brace).es. The statistical analysis calculated the reliability (test-retest reliability and internal consistency) and the validity (convergent and construct validity) of the BSSQ (brace).es.</p> <p>Results</p> <p>BSSQ(brace).es is reliable because of its satisfactory internal consistency (Cronbach's alpha coefficient was 0.809, p < 0.001) and temporal stability (test-retest method with a Pearson correlation coefficient of 0.902 (p < 0.01)).</p> <p>It demonstrated convergent validity with SRS-22 since the Pearson correlation coefficient was 0.656 (p < 0.01). By undertaking an Exploratory Principal Components Analysis, a latent structure was found based on two Components which explicate the variance at 60.8%.</p> <p>Conclusions</p> <p>BSSQ (brace).es is reliable and valid and can be used with Spanish adolescents to assess the stress level caused by the brace.</p
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