446 research outputs found
Application of Real-time PCR for the Detection and Quantification of Oomycetes in Ornamental Nursery Stock
Funding: This research was funded by EUPHRESCO (European Phytosanitary Research Coordi-nation network) and the UK Forestry Commission. Acknowledgments: The authors would like to acknowledge the technical support of Dr. Hedda Weitz and Els Verstappen.Peer reviewedPublisher PD
TRANSITION PROBABILITIES TO EMPLOYMENT AND NON-PARTICIPATION
The analysis of the probability of leaving the unemployment pool is cornrnonly done without distinguishing the exit state. Al1 the people who exit unemployment do not do so into employment, instead some become inactive. In this paper 1 then distinguish and examine the trasition probabilities from unemployment to employment and non-participation. 1 find that the factors that affect the transition probabilities to each state are not necesarily the same, and their effects are different in direction andlor magnitude. El análisis de la probabilidad de salir del desempleo se hace normalmente sin distinguir el estado al cual se va. Todos los individuos que dejan el desempleo no pasan a ser empleados, sino que algunos pasan a la inactividad. En este trabajo distingo y examino las probabilidades de transición del desempleo a el empleo y a la inactividad. Se encuentra que los factores que afectan a las probabilidades de transición a cada uno de los estados no son necesariamente los mismos, y los efectos van en diferente dirección y/o son de diferente magnitud.Análisis del desempleo, modelos de elección cualitativa. Unemployment analisis , qualitative choice models
Higher-level goals in the processing of human action events
The concept of a goal critically separates dynamic events involving humans from other events. Human behaviours are motivated by goals, which are known to the actor but typically inferred on the part of the observer. Goals can be hierarchical in nature, such that a collection of sub-goals (e.g., getting a mug, boiling water) can be nested under a higher-level goal (e.g., making tea), which can be further nested under an even higher-level goal (e.g., making breakfast).
The diverse set of talks in this symposia all highlight the foundational role that goals play in action processing and representation. Eisenberg et al. detail how online prediction of others’ goals shapes observers’ sampling of information during action observation. Howard and Woodward provide evidence that children’s memory for non-human events can be facilitated by priming children with their own goal-directed actions. Loucks and Meltzoff highlight the importance of goal structure in children’s memory for complex action sequences. Finally, Cooper presents a computational model to explain the emergence of goal-directed action hierarchies
Analysis of InGaN nanodots grown by droplet heteroepitaxy using grazing incidence small-angle X-ray scattering and electron microscopy
We present a detailed structural investigation of self-assembled indium gallium nitride nanodots grown on c-plane aluminum nitride templates by the droplet heteroepitaxy technique in a plasma-assisted molecular beam epitaxy reactor. Various growth parameters, including the total coverage of the metal species, relative and total metal effusion fluxes, and nitridation temperature were investigated. Analyses of in situ reflection high-energy electron diffraction patterns and comparison with simulations showed that the resulting crystal structure was a mixture of wurtzite and twinned zinc blende phases, with the zinc blende phase increasingly dominant for lower metal coverages and lower nitridation temperatures, and the wurtzite phase increasingly dominant for higher nitridation temperature. Studies by field emission scanning electron microscopy and atomic force microscopy revealed that the nanodots exhibit trimodal size distributions, with the dot morphologies of the intermediate size mode often resembling aggregations of distinct clusters. Nanodots grown at higher nitridation temperatures had larger inter-dot spacings, with hexagonal in-plane ordering observable at a sufficiently high temperature. Using grazing incidence small angle X-ray scattering, we determined the nanodots to be approximately truncated cone shaped, and extracted the mean radius, height, and inter-dot distance for each distribution. Microstructural investigations of the nanodots by cross-sectional transmission electron microscopy indicated that the majority of the dots were formed in dislocation-free regions, and confirmed that the intermediate size dots were approximately truncated cone shaped and consisted of both zinc blende and wurtzite regions. Mapping of the elemental distributions by energy dispersive X-ray spectroscopy in scanning transmission electron microscopy mode indicated highly nonuniform indium distributions within both small and intermediate size dots which are potentially indicative of indium clustering and kinetically controlled nanoscale phase separation rather than the spinodal decomposition associated with bulk diffusion. The observed enrichment in indium concentration towards the tops of the nanodot layers could be ascribed to the compositional pulling effect.The authors thank Dr. J. Bacon and Dr. D. Nothern for help with the GISAXS and the AFM experiments, respectively. The authors acknowledge the use of the MSE Core Facilities, the Precision Measurement Laboratory, and the FIB/TEM Facility in the Boston University Photonics Center. The authors also acknowledge the NSF MRI Grant No. 1337471 that purchased the Bruker N8 Horizon. The work was supported by the Department of Energy under Grant No. DE-FG02-06ER46332. (1337471 - NSF MRI Grant; DE-FG02-06ER46332 - Department of Energy)Published versio
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Antecedents and performance consequences of international outsourcing
The outsourcing of intermediate products to international suppliers is believed to improve firm performance. We investigate this claim and test key dimensions of the decision to outsource internationally using survey data on 200 manufacturing firms located in the Netherlands. We find that most international outsourcing is intra-regional in nature. Furthermore international outsourcing is a consequence of a firm‟s ability to search and evaluate foreign suppliers, which is co-determined by its size, multinationality, and frequency of cross-border communications. Finally, no performance effects were observed for international or global outsourcing. We conclude international outsourcing is a balancing act between lower production costs abroad and lower transaction costs locally
Towards a Realistic Neutron Star Binary Inspiral: Initial Data and Multiple Orbit Evolution in Full General Relativity
This paper reports on our effort in modeling realistic astrophysical neutron
star binaries in general relativity. We analyze under what conditions the
conformally flat quasiequilibrium (CFQE) approach can generate
``astrophysically relevant'' initial data, by developing an analysis that
determines the violation of the CFQE approximation in the evolution of the
binary described by the full Einstein theory. We show that the CFQE assumptions
significantly violate the Einstein field equations for corotating neutron stars
at orbital separations nearly double that of the innermost stable circular
orbit (ISCO) separation, thus calling into question the astrophysical relevance
of the ISCO determined in the CFQE approach. With the need to start numerical
simulations at large orbital separation in mind, we push for stable and long
term integrations of the full Einstein equations for the binary neutron star
system. We demonstrate the stability of our numerical treatment and analyze the
stringent requirements on resolution and size of the computational domain for
an accurate simulation of the system.Comment: 22 pages, 18 figures, accepted to Phys. Rev.
Dravet syndrome as epileptic encephalopathy: Evidence from long-term course and neuropathology
Dravet syndrome is an epilepsy syndrome of infantile onset, frequently caused by SCN1A mutations or deletions. Its prevalence, long-term evolution in adults and neuropathology are not well known. We identified a series of 22 adult patients, including three adult post-mortem cases with Dravet syndrome. For all patients, we reviewed the clinical history, seizure types and frequency, antiepileptic drugs, cognitive, social and functional outcome and results of investigations. A systematic neuropathology study was performed, with post-mortem material from three adult cases with Dravet syndrome, in comparison with controls and a range of relevant paediatric tissue. Twenty-two adults with Dravet syndrome, 10 female, were included, median age 39 years (range 20–66). SCN1A structural variation was found in 60% of the adult Dravet patients tested, including one post-mortem case with DNA extracted from brain tissue. Novel mutations were described for 11 adult patients; one patient had three SCN1A mutations. Features of Dravet syndrome in adulthood include multiple seizure types despite polytherapy, and age-dependent evolution in seizure semiology and electroencephalographic pattern. Fever sensitivity persisted through adulthood in 11 cases. Neurological decline occurred in adulthood with cognitive and motor deterioration. Dysphagia may develop in or after the fourth decade of life, leading to significant morbidity, or death. The correct diagnosis at an older age made an impact at several levels. Treatment changes improved seizure control even after years of drug resistance in all three cases with sufficient follow-up after drug changes were instituted; better control led to significant improvement in cognitive performance and quality of life in adulthood in two cases. There was no histopathological hallmark feature of Dravet syndrome in this series. Strikingly, there was remarkable preservation of neurons and interneurons in the neocortex and hippocampi of Dravet adult post-mortem cases. Our study provides evidence that Dravet syndrome is at least in part an epileptic encephalopathy
L-band integral field spectroscopy of the HR 8799 planetary system
Stars and planetary system
Active Brownian Particles. From Individual to Collective Stochastic Dynamics
We review theoretical models of individual motility as well as collective
dynamics and pattern formation of active particles. We focus on simple models
of active dynamics with a particular emphasis on nonlinear and stochastic
dynamics of such self-propelled entities in the framework of statistical
mechanics. Examples of such active units in complex physico-chemical and
biological systems are chemically powered nano-rods, localized patterns in
reaction-diffusion system, motile cells or macroscopic animals. Based on the
description of individual motion of point-like active particles by stochastic
differential equations, we discuss different velocity-dependent friction
functions, the impact of various types of fluctuations and calculate
characteristic observables such as stationary velocity distributions or
diffusion coefficients. Finally, we consider not only the free and confined
individual active dynamics but also different types of interaction between
active particles. The resulting collective dynamical behavior of large
assemblies and aggregates of active units is discussed and an overview over
some recent results on spatiotemporal pattern formation in such systems is
given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte
New Aspects of the Temperature-Magnetic Field Phase Diagram of CeB6
We have measured the magnetic field dependence of the paramagnetic to the
field-induced high temperature antiferroquadrupolar magnetically ordered phase
transition is CeB6 from 0 to 60 T using a variety of techniques. It is found
that the field-dependent phase separation line becomes re-entrant above 35 T
and below 10 K. Measurements of resonant ultra-sound, specific heat and neutron
diffraction show conclusively that the zero-field temperature-dependent phase
transition is to a state with no ordered dipole moments, but with second order
transition signatures in both sound attenuation and specific heat.Comment: 4 pages, 4 figures, 11 references, submitted to Physical Review
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