132 research outputs found
The zygotic origin of hybrids from Thompson Seedless grape, Vitis vinifera L.
Seedlings from open pollination and controlled crosses of Thompson Seedless were different from the parent in either fruit color, seed size, flavor or isozyme pattern. These results confirm that plants produced by in ovulo embryo culture of Thompson Seedless are usually zygotic in origin. This is a useful tool for producing hybrid plants from stenospermic seedless genotypes, allowing the hybridization of seedless by seedless and permitting many crosses previously unattainable.Die zygotische Herkunft von Hybriden der Rebsorte Thompson Seedless (Vitis vinifera L.)Um die zygotische Herkunft von Nachkommen der stenospermokarpen Sorte Thompson Seedless abzusichern, wurden aus in vitro kultivierten Samenanlagen Pflanzen herangezogen und eine Reihe von Merkmalen analysiert. Die Sämlinge aus unkontrollierter Bestäubung oder aus gezielter Kreuzung von Thompson Seedless unterschieden sich von der Muttersorte entweder in Beerenfarbe, Samengröße, Aroma oder Isoenzymmuster. Diese Befunde bestätigen, daß die durch in vitro-Kultur der Samenanlagen von Thompson Seedless erzeugten Pflanzen in der Regel zygotischen Ursprungs sind. Die Embryokultur aus Samenanlagen ist eine wertvolle Technik zur Erzeugung von Hybriden aus stenospermokarpen Genotypen; sie erlaubt die Kreuzung mit anderen kernlosen Sorten und ermöglicht viele bisher nicht realisierbare Kreuzungskombinationen
EVALUATING CLINICAL MASTITIS IN DAIRY CATTLE FED MONENSIN
The effect of Monensin on clinical mastitis in dairy cattle was evaluated from data collected at nine geographical clinical field trials using 966 Holstein cows and heifers in the United States and Canada. At each site, a randomized complete block design was conducted. Monensin (Rumensin®) was fed at concentrations of 0, 8, 16, or 24 ppm in a total mixed ration beginning 21 days before first calving for all nine sites, up to 7 days after second calving for six sites, and 203 days after second calving for three sites. Quarter milk samples were taken and cultured to determine the causative pathogen for each mastitis case and if clinical signs were observed the disease data were grouped according to etiology and analyses conducted. Analyses were conducted for all clinical mastitis cases as well as for a breakdown of the clinical mastitis cases into microorganism group levels. A generalized linear mixed model and a linear mixed model were used to determine if there were significant differences in clinical mastitis between the non-zero concentrations of Monensin and controls. Response variables for the clinical mastitis cases that were analyzed using a generalized linear mixed model were Animal rate, Quarter rate, Observation rate, and Incident rate. An additional response variable, Average case duration, was analyzed using a linear mixed model. Inferences from the analyses indicate that Monensin does not influence the susceptibility of dairy cattle to clinical mastitis
THE EFFECT OF MONENSIN ON LACTATION DAIRY COWS: A DOSE RESPONSE EVALUATION
Monensin (Rumensin®) was fed at doses of 0, 8, 16, or 24 ppm to 966 dairy cows in nine different geographical locations in the USA and Canada. A dose response analysis was conducted on the primary variable, milk production efficiency, to determine the most appropriate dose response function, establish a minimum effective dose, and, when possible, determine a maximum effective dose. Linear mixed models (SAS® Proc Mixed v6.12) were fit to the data. Linear contrasts comparing the non-zero doses of monensin to the control were done to initially determine a minimum effective dose from the 3 non-zero design points. In addition, eight predefined linear contrasts were used to initially determine the general linear-plateau shape of a dose response function for each primary variable. A weighted regression analysis of the least squares means and corresponding standard errors was used when it was necessary to discriminate between the competing linear-plateau functions. A non-overlapping confidence interval process was followed, if it was deemed appropriate, to establish a minimum effective dose for a nondesign point. In cases where the dose response function had a plateau, the dose where the plateau began was classified as the “maximum effective dose” (minimum dose for maximum effect). In cases where the dose response function did not have a plateau, the maximum effective dose was the largest dose used in the study if the response rate was significant
Delays to Care in Pediatric Lupus Patients: Data From the Childhood Arthritis and Rheumatology Research Alliance Legacy Registry.
OBJECTIVE: Prompt treatment for lupus is important to prevent morbidity. A potential barrier to early treatment of pediatric lupus is delayed presentation to a pediatric rheumatologist. To better understand factors contributing to delayed presentation among pediatric lupus patients, we examined differences in demographic and clinical characteristics of lupus patients within the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Legacy Registry with regard to time between symptom onset and presentation to a pediatric rheumatologist.
METHODS: We analyzed data from 598 CARRA Legacy Registry participants for differences between those who presented early (withinonset), between 1-3 months (typical presentation), with moderate delays (3-12 months), and with severe delays (≥1 year). Factors associated with early presentation, moderate delay, and severe delay were determined by multinomial logistic regression.
RESULTS: Forty-four percent of patients presented early, while 23% had moderate delays and 9% had severe delays. Family history of lupus, absence of discoid rash, and location in a state with a higher density of pediatric rheumatologists were associated with earlier presentation. Younger age, low household income (
CONCLUSION: Delays to care ≥1 year exist in a notable minority of pediatric lupus patients from the CARRA Legacy Registry. In this large and diverse sample of patients, access to care and family resources played an important role in predicting time to presentation to a pediatric rheumatologist
Large scale quantum simulations: C_60 impacts on a semiconducting surface
We present tight binding molecular dynamics simulations of C_60 collisions on
the reconstructed diamond(111) surface, carried out with an O(N) method and
with cells containing 1140 atoms. The results of our simulations are in very
good agreement with experiments performed under the same impact conditions.
Furthermore our calculations provide a detailed characterization of the
microscopic processes occuring during the collision, and allow the
identification of three impact regimes, as a function of the fullerene incident
energy. Finally, the study of the reactivity between the cluster and the
surface gives insight into the deposition mechanisms of C_60 on semiconducting
substrates
Near-Surface Interface Detection for Coal Mining Applications Using Bispectral Features and GPR
The use of ground penetrating radar (GPR) for detecting the presence of near-surface interfaces is a scenario of special interest to the underground coal mining industry. The problem is difficult to solve in practice because the radar echo from the near-surface interface is often dominated by unwanted components such as antenna crosstalk and ringing, ground-bounce effects, clutter, and severe attenuation. These nuisance components are also highly sensitive to subtle variations in ground conditions, rendering the application of standard signal pre-processing techniques such as background subtraction largely ineffective in the unsupervised case. As a solution to this detection problem, we develop a novel pattern recognition-based algorithm which utilizes a neural network to classify features derived from the bispectrum of 1D early time radar data. The binary classifier is used to decide between two key cases, namely whether an interface is within, for example, 5 cm of the surface or not. This go/no-go detection capability is highly valuable for underground coal mining operations, such as longwall mining, where the need to leave a remnant coal section is essential for geological stability. The classifier was trained and tested using real GPR data with ground truth measurements. The real data was acquired from a testbed with coal-clay, coal-shale and shale-clay interfaces, which represents a test mine site. We show that, unlike traditional second order correlation based methods such as matched filtering which can fail even in known conditions, the new method reliably allows the detection of interfaces using GPR to be applied in the near-surface region. In this work, we are not addressing the problem of depth estimation, rather confining ourselves to detecting an interface within a particular depth range
Ab initio Quantum and ab initio Molecular Dynamics of the Dissociative Adsorption of Hydrogen on Pd(100)
The dissociative adsorption of hydrogen on Pd(100) has been studied by ab
initio quantum dynamics and ab initio molecular dynamics calculations. Treating
all hydrogen degrees of freedom as dynamical coordinates implies a high
dimensionality and requires statistical averages over thousands of
trajectories. An efficient and accurate treatment of such extensive statistics
is achieved in two steps: In a first step we evaluate the ab initio potential
energy surface (PES) and determine an analytical representation. Then, in an
independent second step dynamical calculations are performed on the analytical
representation of the PES. Thus the dissociation dynamics is investigated
without any crucial assumption except for the Born-Oppenheimer approximation
which is anyhow employed when density-functional theory calculations are
performed. The ab initio molecular dynamics is compared to detailed quantum
dynamical calculations on exactly the same ab initio PES. The occurence of
quantum oscillations in the sticking probability as a function of kinetic
energy is addressed. They turn out to be very sensitive to the symmetry of the
initial conditions. At low kinetic energies sticking is dominated by the
steering effect which is illustrated using classical trajectories. The steering
effects depends on the kinetic energy, but not on the mass of the molecules.
Zero-point effects lead to strong differences between quantum and classical
calculations of the sticking probability. The dependence of the sticking
probability on the angle of incidence is analysed; it is found to be in good
agreement with experimental data. The results show that the determination of
the potential energy surface combined with high-dimensional dynamical
calculations, in which all relevant degrees of freedon are taken into account,
leads to a detailed understanding of the dissociation dynamics of hydrogen at a
transition metal surface.Comment: 15 pages, 9 figures, subm. to Phys. Rev.
Atomic diffraction from nanostructured optical potentials
We develop a versatile theoretical approach to the study of cold-atom
diffractive scattering from light-field gratings by combining calculations of
the optical near-field, generated by evanescent waves close to the surface of
periodic nanostructured arrays, together with advanced atom wavepacket
propagation on this optical potential.Comment: 8 figures, 10 pages, submitted to Phys. Rev.
Setting benchmarks for modelling gas–surface interactions using coherent control of rotational orientation states
A fundamental and predictive understanding of molecule-surface interactions is challenging to obtain. Here the authors report an experimental technique allowing direct measurement of the scattering matrix, which reports on the coherent evolution of quantum states of a molecule scattering from a surface
Updated International Tuberous Sclerosis Complex Diagnostic Criteria and Surveillance and Management Recommendations
Background: Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disease affecting multiple body systems with wide variability in presentation. In 2013, Pediatric Neurology published articles outlining updated diagnostic criteria and recommendations for surveillance and management of disease manifestations. Advances in knowledge and approvals of new therapies necessitated a revision of those criteria and recommendations. Methods: Chairs and working group cochairs from the 2012 International TSC Consensus Group were invited to meet face-to-face over two days at the 2018 World TSC Conference on July 25 and 26 in Dallas, TX, USA. Before the meeting, working group cochairs worked with group members via e-mail and telephone to (1) review TSC literature since the 2013 publication, (2) confirm or amend prior recommendations, and (3) provide new recommendations as required. Results: Only two changes were made to clinical diagnostic criteria reported in 2013: “multiple cortical tubers and/or radial migration lines” replaced the more general term “cortical dysplasias,” and sclerotic bone lesions were reinstated as a minor criterion. Genetic diagnostic criteria were reaffirmed, including highlighting recent findings that some individuals with TSC are genetically mosaic for variants in TSC1 or TSC2. Changes to surveillance and management criteria largely reflected increased emphasis on early screening for electroencephalographic abnormalities, enhanced surveillance and management of TSC-associated neuropsychiatric disorders, and new medication approvals. Conclusions: Updated TSC diagnostic criteria and surveillance and management recommendations presented here should provide an improved framework for optimal care of those living with TSC and their families
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