1,558 research outputs found
The discovery of <i>Isocrinus</i> cf. <i>robustus</i> from the Lias Group (Lower Jurassic) near Dunrobin Castle, Sutherland, Scotland
A single stem section (pluricolumnal) belonging to a post-Palaeozoic crinoid (sea lily) is reported from a small outcrop of Lower Jurassic Lias Group strata exposed in low cliff near Dunrobin Castle. This is the first Jurassic crinoid recorded from Eastern Scotland and the small fragment has enough diagnostic characters to be assigned to the species Isocrinus cf. robustus; a crinoid found commonly in the Lower Jurassic of England. The Scottish form collected has unusual morphology that is atypical of the genus
SRA: Fast Removal of General Multipath for ToF Sensors
A major issue with Time of Flight sensors is the presence of multipath
interference. We present Sparse Reflections Analysis (SRA), an algorithm for
removing this interference which has two main advantages. First, it allows for
very general forms of multipath, including interference with three or more
paths, diffuse multipath resulting from Lambertian surfaces, and combinations
thereof. SRA removes this general multipath with robust techniques based on
optimization. Second, due to a novel dimension reduction, we are able to
produce a very fast version of SRA, which is able to run at frame rate.
Experimental results on both synthetic data with ground truth, as well as real
images of challenging scenes, validate the approach
Recent advance in high manufacturing readiness level and high temperature CMOS mixed-signal integrated circuits on silicon carbide
A high manufacturing readiness level silicon carbide (SiC) CMOS technology is presented. The unique process flow enables the monolithic integration of pMOS and nMOS transistors with passive circuit elements capable of operation at temperatures of 300 °C and beyond. Critical to this functionality is the behaviour of the gate dielectric and data for high temperature capacitance–voltage measurements are reported for SiO2/4H-SiC (n and p type) MOS structures. In addition, a summary of the long term reliability for a range of structures including contact chains to both n-type and p-type SiC, as well as simple logic circuits is presented, showing function after 2000 h at 300 °C. Circuit data is also presented for the performance of digital logic devices, a 4 to 1 analogue multiplexer and a configurable timer operating over a wide temperature range. A high temperature micro-oven system has been utilised to enable the high temperature testing and stressing of units assembled in ceramic dual in line packages, including a high temperature small form-factor SiC based bridge leg power module prototype, operated for over 1000 h at 300 °C. The data presented show that SiC CMOS is a key enabling technology in high temperature integrated circuit design. In particular it provides the ability to realise sensor interface circuits capable of operating above 300 °C, accommodate shifts in key parameters enabling deployment in applications including automotive, aerospace and deep well drilling
Bonding mechanism from the impact of thermally sprayed solid particles
Power particles are mainly in solid state prior to impact on substrates from high velocity oxy-fuel (HVOF) thermal spraying. The bonding between particles and substrates is critical to ensure the quality of coating. Finite element analysis (FEA) models are developed to simulate the impingement process of solid particle impact on substrates. This numerical study examines the bonding mechanism between particles and substrates and establishes the critical particle impact parameters for bonding. Considering the morphology of particles, the shear-instability–based method is applied to all the particles, and the energy-based method is employed only for spherical particles. The particles are given the properties of widely used WC-Co powder for HVOF thermally sprayed coatings. The numerical results confirm that in the HVOF process, the kinetic energy of the particle prior to impact plays the most dominant role in particle stress localization and melting of the interfacial contact region. The critical impact parameters, such as particle velocity and temperature, are shown to be affected by the shape of particles, while higher impact velocity is required for highly nonspherical powder
Nitrate leaching under furrow irrigation as affected by crop sequence and tillage
The potential for NO3-N leaching after alfalfa (Medicago saliva L.)
in irrigated crop production depends on cropping sequence and tillage
practices. A 2-yr field experiment in south-central Idaho compared
the NO3-N leached following alfalfa of a conventional tillage bean-bean
(Phaseolus vulgaris L.) rotation with a silage corn (Zea mays
L.)-winter wheat (Triticum aestivum L.) rotation in a conventional
tillage or no-till system. Nitrate leaching was determined by: (i) sampling
the soil solution below the root zone (1.2 and 1.5 m) using
ceramic-tipped samplers and calculating the N movement from the
water balance, and (ii) measuring the change in soil NO3-N at 1.35
to 4.5 m from soil samples taken in the fall and spring to 4.5 m. During
the second growing season, average soil solution NO3-N concentrations
(below the root zone) were 28, 4, and 10 mg L-1 for the bean-bean,
corn-wheat no-till, and corn-wheat tilled treatments, respectively.
The soil NO3-N in 1.35 to 3.3 m at the end of the study was 80 kg
N ha-1 higher for the bean-bean treatment than for the corn-wheat
treatments. The NO3-N that moved below 1.35 m during the 2 yr
was 53 kg ha-1 higher for the bean-bean than for the corn-wheat
treatments. The soil NO3-N in the 1.35 to 3.3 m depth after 2 yr was
21 kg ha-1 higher for the corn-wheat under conventional tillage than
under the no-till system
Screening for pre-eclampsia by maternal factors and biomarkers at 11-13 weeks' gestation
Objective:
To examine the performance of screening for early-, preterm- and term-preeclampsia (PE) at 11 13 weeks’ gestation by maternal factors and combinations of mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), serum placental growth factor (PLGF) and serum pregnancy associated plasma protein A (PAPP A).
Methods
The data for this study were derived from three previously reported prospective non intervention screening studies at 11+0 – 13+6 weeks’ gestation in a combined total of 61,174 singleton pregnancies, including 1,770 (2.9%) that developed PE. Bayes theorem was used to combine the prior distribution of the gestational age at delivery with PE, obtained from maternal characteristics, with various combinations of biomarker multiple of the median (MoM) values to derive the p patient specific risks of delivery with PE at <37 weeks’ gestation. The performance of such screening was estimated.
Results In pregnancies that develop ed PE , compared to those without PE, the MoM values of UtA-PI and MAP were increased and PAPP A and PLGF were decreased and the deviation from normal was greater for early than late PE for all four biomarkers. Combined screening by maternal factors, UtA-PI, MAP and PLGF predicted 90% of early PE, 75% of preterm PE and 4 1 % of term PE, at screen positive rate of 10%; inclusion of PAPP A did not improve the performance of screening The performance of screening depended on the racial origin of the women; in screening by a combination of maternal factors, MAP, UtA-PI and PLGF and use of the risk cut off of 1 in 10 0 for PE at <37 weeks in Caucasian women, the screen positive rate was 10% and detection rates for early --, preterm and term PE were 88%, 69% and 40%, respectively. With the same
method of screening and risk cut off in women of Afro Caribbean racial origin, the screen positive rate was 34% and detection rates for early --, preterm and term PE were 100%,
92% and 75%, respectively.
Conclusion
Screening by maternal factors and biomarkers at 11-13 weeks’ gestation can identify a high proportion of pregnancies that develop early- and preterm-PE
Controlling nitrate leaching and erosion on irrigated land
New integrated agronomic cropping systems that nearly eliminate irrigation-induced erosion,
significantly reduce nitrate leaching potential, increase crop utilization of nitrogen from legume
sources and fertilizer, improve irrigation uniformity, decrease production costs, and increase net
profits have resulted from several years of research at Kimberly, Idaho. These systems include
growing corn or cereal without tillage following alfalfa to efficiently utilize nitrogen from the
legume and reduce irrigation-induced erosion. Where no corn was grown following alfalfa,
nitrate-N accumulated up to 550 lbs/ac in the upper 5 feet of soil compared to only 50 lbs/ac
where corn was grown. Where beans were grown for two seasons following alfalfa, nitrate-N
leaching was 50 lbs/ac more than where corn and then winter wheat were grown. Banding
nitrogen fertilizer on the opposite side of the corn row from the irrigation furrow used all season
reduced nitrate leaching as compared to where a furrow was irrigated on the same side of the row
as the fertilizer band. Nitrate moves below the root zone during wet winters by deep drainage
and pass through flow. Polyacrylamide (PAM) concentrations of 10 ppm or less applied into the
irrigation water can almost eliminate furrow erosion, and it increases infiltration. Applying
cheese whey alone and in combination with straw at whey rates of 12 gallons and straw rates
of 4 lbs/100 ft of row before beginning irrigations reduced sediment loss by more than 95%
Theory of coherent acoustic phonons in InGaN/GaN multi-quantum wells
A microscopic theory for the generation and propagation of coherent LA
phonons in pseudomorphically strained wurzite (0001) InGaN/GaN multi-quantum
well (MQW) p-i-n diodes is presented. The generation of coherent LA phonons is
driven by photoexcitation of electron-hole pairs by an ultrafast Gaussian pump
laser and is treated theoretically using the density matrix formalism. We use
realistic wurzite bandstructures taking valence-band mixing and strain-induced
piezo- electric fields into account. In addition, the many-body Coulomb
ineraction is treated in the screened time-dependent Hartree-Fock
approximation. We find that under typical experimental conditions, our
microscopic theory can be simplified and mapped onto a loaded string problem
which can be easily solved.Comment: 20 pages, 17 figure
Forward-in-Time, Spatially Explicit Modeling Software to Simulate Genetic Lineages Under Selection
SELECTOR is a software package for studying the evolution of multiallelic genes under balancing or positive selection while simulating complex evolutionary scenarios that integrate demographic growth and migration in a spatially explicit population framework. Parameters can be varied both in space and time to account for geographical, environmental, and cultural heterogeneity. SELECTOR can be used within an approximate Bayesian computation estimation framework. We first describe the principles of SELECTOR and validate the algorithms by comparing its outputs for simple models with theoretical expectations. Then, we show how it can be used to investigate genetic differentiation of loci under balancing selection in interconnected demes with spatially heterogeneous gene flow. We identify situations in which balancing selection reduces genetic differentiation between population groups compared with neutrality and explain conflicting outcomes observed for human leukocyte antigen loci. These results and three previously published applications demonstrate that SELECTOR is efficient and robust for building insight into human settlement history and evolution
Templates for Convex Cone Problems with Applications to Sparse Signal Recovery
This paper develops a general framework for solving a variety of convex cone
problems that frequently arise in signal processing, machine learning,
statistics, and other fields. The approach works as follows: first, determine a
conic formulation of the problem; second, determine its dual; third, apply
smoothing; and fourth, solve using an optimal first-order method. A merit of
this approach is its flexibility: for example, all compressed sensing problems
can be solved via this approach. These include models with objective
functionals such as the total-variation norm, ||Wx||_1 where W is arbitrary, or
a combination thereof. In addition, the paper also introduces a number of
technical contributions such as a novel continuation scheme, a novel approach
for controlling the step size, and some new results showing that the smooth and
unsmoothed problems are sometimes formally equivalent. Combined with our
framework, these lead to novel, stable and computationally efficient
algorithms. For instance, our general implementation is competitive with
state-of-the-art methods for solving intensively studied problems such as the
LASSO. Further, numerical experiments show that one can solve the Dantzig
selector problem, for which no efficient large-scale solvers exist, in a few
hundred iterations. Finally, the paper is accompanied with a software release.
This software is not a single, monolithic solver; rather, it is a suite of
programs and routines designed to serve as building blocks for constructing
complete algorithms.Comment: The TFOCS software is available at http://tfocs.stanford.edu This
version has updated reference
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