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The development of laser wakefield accelerators (LWFA) over the past several years has led to an interest in very compact sources of X-ray radiation – such as “table-top” free electron lasers. However, the use of conventional undulators using permanent magnets also implies system sizes which are large. In this work, we assess the possibilities for the use of novel mini-undulators in conjunction with a LWFA so that the dimensions of the undulator become comparable with the acceleration distances for LWFA experiments (i.e., centimeters). The use of a prototype undulator using laser machining of permanent magnets for this application is described and the emission characteristics and limitations of such a system are determined. Preliminary electron propagation and X-ray emission measurements are taken with a LWFA electron beam at the University of Michigan.
Stellar coronal mass ejections (CMEs) may play an important role in stellar and planetary evolution, therefore the knowledge on parameter distributions of this energetic activity phenomenon is highly relevant. During the last years several attempts have been made to detect stellar CMEs of late-type main-sequence and pre main-sequence stars from dedicated optical spectroscopic observations. Up to now only a handful of distinct stellar CME detections are known which contradicts the results from stellar CME modelling, which predict higher CME rates. We report on dedicated ongoing and future observational attempts to detect stellar CMEs and discuss the observational results with respect to the results from stellar CME modelling.
Identifying youth who may engage in future substance use could facilitate early identification of substance use disorder vulnerability. We aimed to identify biomarkers that predicted future substance use in psychiatrically un-well youth.
LASSO regression for variable selection was used to predict substance use 24.3 months after neuroimaging assessment in 73 behaviorally and emotionally dysregulated youth aged 13.9 (s.d. = 2.0) years, 30 female, from three clinical sites in the Longitudinal Assessment of Manic Symptoms (LAMS) study. Predictor variables included neural activity during a reward task, cortical thickness, and clinical and demographic variables.
Future substance use was associated with higher left middle prefrontal cortex activity, lower left ventral anterior insula activity, thicker caudal anterior cingulate cortex, higher depression and lower mania scores, not using antipsychotic medication, more parental stress, older age. This combination of variables explained 60.4% of the variance in future substance use, and accurately classified 83.6%.
These variables explained a large proportion of the variance, were useful classifiers of future substance use, and showed the value of combining multiple domains to provide a comprehensive understanding of substance use development. This may be a step toward identifying neural measures that can identify future substance use disorder risk, and act as targets for therapeutic interventions.
Photoelectrochemical (PEC) water splitting for hydrogen production is a promising technology that uses sunlight and water to produce renewable hydrogen with oxygen as a by-product. In the expanding field of PEC hydrogen production, the use of standardized screening methods and reporting has emerged as a necessity. This article is intended to provide guidance on key practices in characterization of PEC materials and proper reporting of efficiencies. Presented here are the definitions of various efficiency values that pertain to PEC, with an emphasis on the importance of solar-to-hydrogen efficiency, as well as a flow chart with standard procedures for PEC characterization techniques for planar photoelectrode materials (i.e., not suspensions of particles) with a focus on single band gap absorbers. These guidelines serve as a foundation and prelude to a much more complete and in-depth discussion of PEC techniques and procedures presented elsewhere.
The Working Group FITS (WG-FITS) is the international control authority for the Flexible Image Transport System (FITS) data format. The WG-FITS was formed in 1988 by a formal resolution of the IAU XX General Assembly in Baltimore (MD, USA), 1988, to maintain the existing FITS standards and to approve future extensions to FITS.
Most ecological studies of fungi associated with tropical plants have focused on the rhizosphere or phyllosphere of seedlings, saplings and adult trees (Augspurger 1983, 1984; Bell et al. 2006, Gilbert 2002, Gilbert et al. 2002, Husband et al. 2002, Kiers et al. 2000, Mangan et al. 2004). However, fungi also infect the seeds of tropical trees, reducing seed survival and potentially affecting adult distributions (Gallery et al. 2007a, b). Fungicide experiments have shown that fungal and oomyceteous pathogens are the major cause of seed mortality in the soil for a variety of tropical pioneers (Dalling et al. 1998, Gallery et al. 2007b, Murray & Garcia 2002), which depend on recruitment from seed banks to colonize gaps and other disturbances in mature forest (Alvarez-Buylla & Martinez-Ramos 1990, Dalling et al. 1997, Hall & Swaine 1980). Persistence in the soil prolongs exposure of seeds to infection by soil-borne fungi and is especially problematic for small-seeded species with thin fruit or seed walls (Baskin & Baskin 1998, Blaney & Kotanen 2002, Crist & Friese 1993). At present little is known about the host affinity of fungi associated with seeds of tropical trees, and consequently, whether seed-infecting fungi influence plant species coexistence through differential infection of, or effects on, potential hosts.
Insects are by far the most diverse group of multicellular organisms on our planet. Of about 1,625,000 described species of prokaryotes, protoctists, fungi, plants and animals, more than 1 million is represented by arthropods, of which insects constitute the largest group with about 854,000 described species. The estimations of the number of still undescribed species, especially in the vanishing tropical rainforests, are ranging from 2 million to 80 million species! The most species-rich groups within insects are the holometabolous orders Coleoptera (beetles), Hymenoptera (ants, wasps and bees), Diptera (mosquitoes and flies) and Lepidoptera (moths and butterflies). Among the hemimetabolous orders, which lack a pupal stage in their ontogenetic development, the Hemiptera (aphids, scale insects, cicadas and bugs) are the largest group, while all other insect orders have much fewer species.
Even though relatively small animals, the extremely large number of individuals makes insects a very significant part of the total terrestrial biomass in many biotopes. For example, in tropical rainforests, the ants and termites have a higher total biomass than all the vertebrates combined.
Insects are not only diverse in terms of species number and number of individuals, but also in their astonishing anatomical and ecological variability. Insects populate nearly every available habitat on the planet, except for the open seas and the frozen polar regions.
The changing surface geometry of the glacier Midre Lovénbreen on Svalbard was investigated using LiDAR data acquired on 9 August 2003 and again on 5 July 2005. The data were processed to generate Digital Elevation Models (DEMs) of unprecedentedly high spatial resolution (2 m) and accuracy (better than 0.15 m). Comparison of the two DEMs allowed the mass balance of the glacier to be determined as more negative than −0.62 m yr−1 water equivalent, about twice as negative as the value estimated from in situ measurements. Comparison of the DEMs also showed that the area of the glacier decreased by around 0.3%, and the position of its margin retreated by around 14 m, from 2003 to 2005. It was also possible to track the motion of fine-scale features in the surface geometry such as meltwater channels, and hence to determine the glacier's surface velocity, in some areas. Typical average speeds were around 1–2 cm per day.
Esophageal replacement is an infrequent procedure required after great effort has been put forth to save the native esophagus. The most frequent indications for esophageal replacement include long-gap esophageal atresia with or without tracheoesophageal fistula, and esophageal strictures most often due to caustic ingestion or secondary to gastroesophageal reflux disease. Although children with esophageal atresia, gastroesophageal reflux disease, and to a lesser degree, caustic ingestion, are commonly encountered in pediatric surgery, they rarely require esophageal replacement. Our ability to anastomose the two ends of the esophagus in infants with esophageal atresia has improved over the years with techniques such as circular myotomies, upper pouch flaps, and dilation or stretching of the upper pouch and distal esophagus prior to anastomosis. Caustic ingestions have become more infrequent with the changes in packaging of hazardous materials in the home. Peptic strictures due to acid reflux are on the decline due to our heightened awareness of the long-term damage caused by gastroesophageal reflux disease, and our improved medical armamentarium available to control acid reflux. In addition, novel procedures to save the strictured esophagus have been reported. These include stricturoplasty with placement of a vascularized colonic patch, and stenting of caustic esophageal strictures combined with steroid and acid reducing therapy. Despite these improvements, and our understanding that even a somewhat compromised native esophagus may be desirable when compared to the alternatives, there is a distinct subset of infants and children who will require an esophageal replacement.
In Europe, more than 60 breeds are described by the national associations of rabbit breeders. However, these breeds are scarcely used in the commercial production of rabbit meat in Europe, which is based mainly on commercial strains. A European programme, coordinated by the I. N. R. A., has been initiated to realise the inventory of all these breeds and to evaluate the zootechnical value and the genetic characteristics of some of them. Through the European association of rabbit breeders and the FAO national focal points, all the European countries have been asked to fill out a questionnaire describing their populations of rabbits. A data bank is being set up, which will be included in the FAO (DAD-IS) and EAAP data banks. A sample of 10 breeds has been chosen (Flemish Giant, French Lop, Belgian Hare, Vienna White, Champagne Argente, Thuringer, Fauve de Bourgogne, Chinchilla, Himalayan, British). Their zootechnical value (reproduction, growth and carcass traits) is being evaluated on three experimental farms, in comparison with a control breed. At the same time, their genetic polymorphism and the genetic distances between these 10 breeds are calculated on the basis of microsatellites, mitochondrial DNA, other genetic markers and protein polymorphism. Finally, a bank of frozen embryos from these 10 breeds is being constituted.
Atomic Force Acoustic Microscopy is a near-field technique which combines the ability in using ultrasonics to image elastic properties with the high lateral resolution of scanning probe microscopes. We present a technique to measure the contact stiffness and the Young's modulus of sample surfaces quantitatively with a resolution of approximately 20 rum exploiting the contact resonance frequencies of standard cantilevers used in Atomic Force Microscopy. The Young's modulus of nanocrystalline ferrite films have been measured as a function of oxidation temperature. Furthermore images showing the domain structure of piezoelectric lead zirconate titanate ceramics have been taken.
An annual legume cover crop was evaluated in pecan orchards to increase coccinellids that would reduce pecan aphids. Treatments were a ‘Dixie’ crimson clover and hairy vetch mixture and a grass sod. Coccinellids were abundant on the legume ground covers, but coccinellid density in the tree canopy was rarely affected by ground cover treatment. There were substantial differences between the coccinellid species collected from the legumes and from the trees. In Oklahoma, Olla v-nigrum (Mulsant) and Cycloneda munda (Say) were the main species in the trees, while Hippodamia convergens Guerin, Coccinella septempunctata L, and Coleomegilla maculata lengi Timberlake were dominant species in the legumes. In Georgia, Harmonia axyridis (Pallas) was the dominant species in the trees, and C. septempunctata in the legumes. Pecan aphids at two Oklahoma sites usually were not affected by cover crop treatment, but at the Georgia site, early-season aphids frequently were lower with a legume cover crop than with a grass sod. The accumulated effect of all aphid predators and parasitoids attracted to the legume aphids may have reduced the density of the pecan aphid.
Even if we recognize that the delta-lognormal model provides
an excellent fit to a large variety of data, the question remains as
to what we actually learn from such a model, which could be seen as
merely another multiparameter account? Do we welcome such an
encompassing account, or do we expect to learn more from the
limitations that become apparent when applying dedicated models
addressing specific classes of movements?
The extended ranges (2–3 times theoretical) for hydration from an ambient atmosphere or water immersion and other anomalous ranges for property changes in ion-implanted fused silica are explained on the basis of a stress corrosion model (Michalske-Bunker). The results for the hydration of implanted soda-lime glass are similar to fused silica with the added feature of compositional modification due to the near-surface removal of alkali.
We evaluated selected cool-season annual and perennial legumes as potential ground covers to supply nitrogen and to increase beneficial arthropod populations in a pecan orchard. Densities of aphids (Homoptera: Aphididae), lady beetles (Coleoptera: Coccinellidae), damsel bug (Hemiptera: Nabidae), green lacewings (Neuroptera: Chrysopidae), brown lacewings (Neuroptera: Hemerobiidae), hover flies (Diptera: Syrphidae), spined soldier bug and other stink bugs (Hemiptera: Pentatomidae), and spiders (Araneida) were monitored at 7–14 day intervals during the growing season for three years. Aboveground biomass production and nitrogen content of the legumes was measured for two years. Aphids peaked during early spring each year, with the highest density usually on ‘Dixie’ crimson clover and ‘Kenland’ red clover. Density of lady beetles was positively correlated with that of aphids, but spider densities were not. Other arthropods usually were not abundant. Nitrogen in the tops of the annual legumes ranged from 20 kg/ha to 89 kg/ha when assessed after a single harvest at anthesis; for the perennial legumes it was from 108 kg/ha to 179 kg/ha following two harvests in June and September. We chose two annual legumes (‘Dixie’ crimson clover and hairy vetch) and two perennial legumes (‘Louisiana S-1’ white clover and ‘Kenland’ red clover) for further evaluation.
Rickettsia-like organisms (RLO) from tsetse midguts and mosquito cell cultures showed high levels of endochitinase activity. A line of Glossina morsitans morsitans highly susceptible to midgut trypanosome infection and with high incidence of RLO infection showed significantly greater chitinolytic activity than G. austeni which had low RLO incidence and were correspondingly refractory to midgut infection. Midgut infection rates of Trypanosoma brucei rhodesiense in G. m. morsitans showed a dose-related increase when flies were fed N-acetyl-D-glucosamine (GlcNAc) in the infective meal and for 4 subsequent days. A model is proposed for susceptibility to trypanosome infection based on the generation of GlcNAc by RLO endochitinase activity in tsetse pupae inhibiting midgut lectin in teneral flies.