3,512 research outputs found
Processing experiments on non-Czochralski silicon sheet
A program is described which supports and promotes the development of processing techniques which may be successfully and cost-effectively applied to low-cost sheets for solar cell fabrication. Results are reported in the areas of process technology, cell design, cell metallization, and production cost simulation
HST and Spitzer point source detection and optical extinction in powerful narrow-line radio galaxies
We present the analysis of infrared HST and Spitzer data for a sample of 13
FRII radio galaxies at 0.03<z<0.11 that are classified as narrow-line radio
galaxies (NLRG). In the context of the unified schemes for active galactic
nuclei (AGN), our direct view of the AGN in NLRG is impeded by a parsec-scale
dusty torus structure. Our high resolution infrared observations provide new
information about the degree of extinction induced by the torus, and the
incidence of obscured AGN in NLRG.
We find that the point-like nucleus detection rate increases from 25 per cent
at 1.025m, to 80 per cent at 2.05m, and to 100 per cent at 8.0m.
This supports the idea that most NLRG host an obscured AGN in their centre. We
estimate the extinction from the obscuring structures using X-ray, near-IR and
mid-IR data. We find that the optical extinction derived from the 9.7m
silicate absorption feature is consistently lower than the extinction derived
using other techniques. This discrepancy challenges the assumption that all the
mid-infrared emission of NLRG is extinguished by a simple screen of dust at
larger radii. This disagreement can be explained in terms of either weakening
of the silicate absorption feature by (i) thermal mid-IR emission from the
narrow-line region, (ii) non-thermal emission from the base of the radio jets,
or (iii) by direct warm dust emission that leaks through a clumpy torus without
suffering major attenuation.Comment: 18 pages, 7 figures, 8 tables, accepted for publication in MNRA
The large N limit of M2-branes on Lens spaces
We study the matrix model for N M2-branes wrapping a Lens space L(p,1) =
S^3/Z_p. This arises from localization of the partition function of the ABJM
theory, and has some novel features compared with the case of a three-sphere,
including a sum over flat connections and a potential that depends
non-trivially on p. We study the matrix model both numerically and analytically
in the large N limit, finding that a certain family of p flat connections give
an equal dominant contribution. At large N we find the same eigenvalue
distribution for all p, and show that the free energy is simply 1/p times the
free energy on a three-sphere, in agreement with gravity dual expectations.Comment: 28 pages, 4 figure
A broad look at charcoal rot in the Northern Region broadacre crops through soil sampling and in-crop surveys
Macrophomina phaseolina (Tassi) Goid. is a generalist
soil-born pathogen, which is endemic to Australia. The
pathogen has a broad host-range of both monocot and
dicot plant species which include numerous weed and
crop plant species (1, 2). The disease is most commonly
identified with summer crops, e.g. soybean, sorghum,
sunflower, maize and mungbean (3) and occurs most
often when hot, dry conditions occur during the growing
season. Current estimates predict that north-eastern
Australia will become hotter and dryer as a result of
climate change (4, 5). Thus, it is likely that conditions
favouring the development of this disease will become
more common in the future. However, to date, no work
has been done to determine the extent of the
pathogen’s presence in Australian soils, in-paddock
spatial variability, or the occurrence of the disease as
correlated with pathogen presence and population
levels. In this paper, we present findings from soil
sampling and end-of-season disease assessments in
sorghum paddocks across northern New South Wales
(NNSW), south eastern Queensland (SEQ) and central
Queensland (CQ) during the 2016/17 and 2017/18
summer cropping seasons
What can we learn from population genomics studies of Curtobacterium flaccumfaciens pv. flaccumfaciens, the cause of tan spot on mungbean?
The bacterium Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff) is the cause of tan spot (in some regions known as ‘wilt’) on mungbean (Vigna radiata) and other legumes worldwide. The pathogen was first reported in mungbean paddocks in Queensland in 1984, and subsequently in New South Wales in 1986, causing yield losses of up to 25% in hot and dry seasons. No chemical control is available, and disease management relies on pathogen exclusion, through the use of clean seed, and deployment of moderately susceptible varieties. Breeding programs are currently working to incorporate better resistance into new mungbean varieties. The success of breeding programs depends on a thorough understanding of the genetic diversity and evolution of the pathogen population(s). This project was designed to elucidate the genotypic diversity of Cff population(s) and investigate sources of inoculum that contribute to tan spot epidemics in the northern grains region (Queensland and northern New South Wales). Whole genome re-sequencing of 100 Cff isolates detected moderate genotypic diversity, with a narrower genetic background compared to the global Cff population. One highly adapted clonal lineage was found to dominate the population with a frequency of 45%. This study showcases how population genomics studies can be used to test hypotheses relating to disease epidemiology and provide useful information for resistance breeding programs. The results provide insights on Cff population structure and epidemiology, and have direct application for breeding programs by providing a set of Cff isolates that represent the genetic diversity of the pathogen population(s) in the northern grains region
Surface Hydrogen Modeling of Super Soft X-ray Sources: Are They Supernova Ia Progenitors?
Nova explosions occur on the white dwarf (WD) component of a Cataclysmic
Variable stellar system which is accreting matter lost by a companion. A Type
Ia supernova explosion is thought to result when a WD, in a similar binary
configuration, grows in mass to the Chandrasekhar Limit. Here, we present
calculations of accretion of Solar matter, at a variety of mass accretion
rates, onto hot (K), luminous (30L), massive
(1.25M, 1.35M) Carbon-Oxygen WDs. In contrast to our nova
simulations where the WD has a low initial luminosity and a thermonuclear
runaway (TNR) occurs and ejects material, these simulations do not eject
material (or only a small fraction of the accreted material) and the WD grows
in mass. A hydrogen TNR does not occur because hydrogen fuses to helium in the
surface layers, and we call this process Surface Hydrogen Burning (SHB). As the
helium layer grows in mass, it gradually fuses either to carbon and oxygen or
to more massive nuclei depending on the WD mass and mass accretion rate. If
such a WD were to explode in a SN Ia event, therefore, it would show neither
hydrogen nor helium in its spectrum as is observed. Moreover, the luminosities
and effective temperatures of our simulations agree with the observations of
some of the Super Soft X-ray Binary Sources and, therefore, our results
strengthen previous speculation that some of them (CAL 83 and CAL 87 for
example) are probably progenitors of SN Ia explosions. Finally, we have
achieved SHB for values of the mass accretion rate that almost span the
observed values of the Cataclysmic Variables.Comment: Accepted by APJL, 4 pages, 1 figure, LaTex (uses emulateapj.sty
Electronic structure of NiSSe across the phase transition
We report very highly resolved photoemission spectra of NiS(1-x)Se(x) across
the so-called metal-insulator transition as a function of temperature as well
as composition. The present results convincingly demonstrate that the low
temperature, antiferromagnetic phase is metallic, with a reduced density of
states at E. This decrease is possibly due to the opening of gaps along
specific directions in the Brillouin zone caused by the antiferromagnetic
ordering.Comment: Revtex, 4 pages, 3 postscript figure
Some factors influencing populations of the European corn borer, Ostrinia nubilalis (Hubner) in the north central states: Resistance of corn, time of planting and weather conditions Part II, 1958-1962
A cooperative project was conducted by the agricultural experiment stations of Iowa, Minnesota and Ohio and the U. S. Department of Agriculture to study the effects of weather, planting date and resistant hybrids as factors influencing populations of the European com borer, Ostrinia nubilalis (Hübner). Identical studies were carried out at Ankeny, Iowa; Waseca, Minnesota; and Wooster, Ohio, during a 10-year period, 1953-1962.
The first 4 years of the study (1953-56) were reported by Everett et al. (1958). The work reported herein is a companion bulletin to the Everett et al. (1958) publication and deals with the results of experiments conducted during 1958-1962.
The experimental design was a randomized block, split plot with five replications. The whole plot treatments were four hybrid-planting date combinations consisting of early- or late-planting dates and susceptible or resistant hybrids. The subplot treatments consisted of a factorial arrangement of all possible combinations of three levels of infestation (zero, natural and natural + 3 egg masses) by first brood and the same three levels of infestation by second-brood borers. Temperature and rainfall records were kept at each of the three stations. Borer population and injury to the plant were recorded at the end of the first brood and in the fall. Yield data were collected
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