599 research outputs found
Quantum tunneling of two coupled single-molecular magnets
Two single-molecule magnets are coupled antiferromagnetically to form a
supramolecule dimer. We study the coupling effect and tunneling process by
means of the numerical exact diagonalization method, and apply them to the
recently synthesized supramoleculer dimer [Mn4]2 The model parameters are
calculated for the dimer based on the tunneling process. The absence of
tunneling at zero field and sweeping rate effect on the step height in the
hysterisis loops are understood very well in this theory.Comment: 4 pages including 3 figure and 1 tabl
Suppression of Quantum Phase Interference in Molecular Magnets Fe₈ with Dipolar-Dipolar Interaction
Renormalized tunnel splitting with a finite distribution in the biaxial spin
model for molecular magnets is obtained by taking into account the dipolar
interaction of enviromental spins. Oscillation of the resonant tunnel splitting
with a transverse magnetic field along the hard axis is smeared by the finite
distribution which subsequently affects the quantum steps of hysteresis curve
evaluated in terms of the modified Landau-Zener model of spin flipping induced
by the sweeping field. We conclude that the dipolar-dipolar interaction drives
decoherence of quantum tunnelling in molcular magnets Fe₈, which explains
why the quenching points of tunnel spliting between odd and even resonant
tunnelling predcited theoretically were not observed experimentally.Comment: 5 pages including 3 figure and 1 table. To appear in Physical Review
Detection and Identification of Salmonella enterica, Escherichia coli, and Shigella spp. via PCR-ESI-MS: Isolate Testing and Analysis of Food Samples
An assay to identify the common food-borne pathogens Salmonella, Escherichia coli, Shigella, and Listeria monocytogenes was developed in collaboration with Ibis Biosciences (a division of Abbott Molecular) for the Plex-ID biosensor system, a platform that uses electrospray ionization mass spectroscopy (ESI-MS) to detect the base composition of short PCR amplicons. The new food-borne pathogen (FBP) plate has been experimentally designed using four gene segments for a total of eight amplicon targets. Initial work built a DNA base count database that contains more than 140 Salmonella enterica, 139 E. coli, 11 Shigella, and 36 Listeria patterns and 18 other Enterobacteriaceae organisms. This assay was tested to determine the scope of the assay\u27s ability to detect and differentiate the enteric pathogens and to improve the reference database associated with the assay. More than 800 bacterial isolates of S. enterica, E. coli, and Shigella species were analyzed. Overall, 100% of S. enterica, 99% of E. coli, and 73% of Shigella spp. were detected using this assay. The assay was also able to identify 30% of the S. enterica serovars to the serovar level. To further characterize the assay, spiked food matrices and food samples collected during regulatory field work were also studied. While analysis of preenrichment media was inconsistent, identification of S. enterica from selective enrichment media resulted in serovar-level identifications for 8 of 10 regulatory samples. The results of this study suggest that this high-throughput method may be useful in clinical and regulatory laboratories testing for these pathogens
Registration of ‘Hallam’ Wheat
‘Hallam’ (Reg. no. CV-983, PI 638790) is a hard red winter wheat (Triticum aestivum L.) cultivar developed cooperatively by the Nebraska Agricultural Experiment Station and the USDA-ARS and released in 2005 by the developing institutions. Hallam was released primarily for its superior adaptation to rainfed wheat production systems in eastern Nebraska. The name Hallam was chosen to honor Hallam, NE, a town and its people rebuilding after a tornado.
Hallam was selected from the cross ‘Brule’ (Schmidt et al., 1983)/‘Bennett’ (Schmidt et al., 1981)//‘Niobrara’ (Baenziger et al., 1996) that was made in 1992. The F1 generation was grown in the greenhouse and the F2 to F3 generations were advanced using the bulk breeding method in the field at Mead, NE. In 1995, single F3:4 rows were planted for selection. Hallam was selected in the F4 and there was no further selection thereafter.
Hallam was evaluated as NE98471 in Nebraska yield nurseries starting in 1999, in the Northern Regional Performance Nursery in 2001 and 2002, and in Nebraska cultivar performance trials from 2002 to 2004. In the Nebraska cultivar performance trials, it was narrowly adapted and performs best in eastern Nebraska. The average Nebraska rainfed yield of Hallam of 4110 kg ha-1 (41 environments from 2002 to 2004) was greater than the yields of ‘Wahoo’ (4030 kg ha-1; Baenziger et al., 2002), ‘Alliance’ (3880 kg ha-1; Baenziger et al., 1995), and ‘Harry’ (4000 kg ha-1; Baenziger et al., 2004b), but was lower than ‘Millennium’ (4180 kg ha-1; Baenziger et al., 2001) and ‘Wesley’ (4210 kg ha-1; Peterson et al., 2001). In its primary area of adaptation (eastern Nebraska), Hallam has yielded 4540 kg ha-1 (five environments), which was greater than Wesley (4150 kg ha-1), Millennium (4250 kg ha-1), Wahoo (3940 kg ha-1), and Alliance (3900 kg ha21). In the Northern Regional Performance Nursery, Hallam ranked 14th of 30 in 2001 (12 environments) and fourth of 25 entries in 2002 (13 environments) and averaged 100 kg ha-1 more grain yield than ‘Nekota’ (Haley et al., 1996). Hallam is not recommended for use in irrigated production systems where other wheat cultivars with superior performance, especially with better straw strength (described below), would be recommended.
Other measurements of performance from comparison trials show that Hallam is moderately early in maturity (142 d after January 1, five environments), about 2.5 d and 1.2 d earlier flowering than Millennium and Wesley, respectively. Hallam is a semidwarf wheat cultivar. Hallam has a medium short coleoptile (46 mm), as expected for a semidwarf wheat cultivar, and is shorter than ‘Goodstreak’ (61 mm; Baenziger et al., 2004a) and slightly longer than semidwarf wheat cultivars such as Harry (36 mm). The mature plant height of Hallam (86 cm) is 3 cm shorter than Millennium and 6 cm taller than Wesley (41 environments). Hallam has moderate straw strength (45% lodged), similar to Wahoo (46% lodged), but worse than Wesley (34% lodged) in those environments (3) where severe lodging was found. The winter hardiness of Hallamis good to very good, similar to ‘Abilene’ (PI 511307) and comparable to other winter wheat cultivars adapted and commonly grown in Nebraska
Ganoderma lucidum reduces obesity in mice by modulating the composition of the gut microbiota
Obesity is associated with low-grade chronic inflammation and intestinal dysbiosis. Ganoderma lucidum is a medicinal mushroom used in traditional Chinese medicine with putative anti-diabetic effects. Here, we show that a water extract of Ganoderma lucidum mycelium (WEGL) reduces body weight, inflammation and insulin resistance in mice fed a high-fat diet (HFD). Our data indicate that WEGL not only reverses HFD-induced gut dysbiosis—as indicated by the decreased Firmicutes-to-Bacteroidetes ratios and endotoxin-bearing Proteobacteria levels—but also maintains intestinal barrier integrity and reduces metabolic endotoxemia. The anti-obesity and microbiota-modulating effects are transmissible via horizontal faeces transfer from WEGL-treated mice to HFD-fed mice. We further show that high molecular weight polysaccharides (\u3e300 kDa) isolated from the WEGL extract produce similar anti-obesity and microbiota-modulating effects. Our results indicate that G. lucidum and its high molecular weight polysaccharides may be used as prebiotic agents to prevent gut dysbiosis and obesity-related metabolic disorders in obese individuals
Registration of ‘Hallam’ Wheat
‘Hallam’ (Reg. no. CV-983, PI 638790) is a hard red winter wheat (Triticum aestivum L.) cultivar developed cooperatively by the Nebraska Agricultural Experiment Station and the USDA-ARS and released in 2005 by the developing institutions. Hallam was released primarily for its superior adaptation to rainfed wheat production systems in eastern Nebraska. The name Hallam was chosen to honor Hallam, NE, a town and its people rebuilding after a tornado.
Hallam was selected from the cross ‘Brule’ (Schmidt et al., 1983)/‘Bennett’ (Schmidt et al., 1981)//‘Niobrara’ (Baenziger et al., 1996) that was made in 1992. The F1 generation was grown in the greenhouse and the F2 to F3 generations were advanced using the bulk breeding method in the field at Mead, NE. In 1995, single F3:4 rows were planted for selection. Hallam was selected in the F4 and there was no further selection thereafter.
Hallam was evaluated as NE98471 in Nebraska yield nurseries starting in 1999, in the Northern Regional Performance Nursery in 2001 and 2002, and in Nebraska cultivar performance trials from 2002 to 2004. In the Nebraska cultivar performance trials, it was narrowly adapted and performs best in eastern Nebraska. The average Nebraska rainfed yield of Hallam of 4110 kg ha-1 (41 environments from 2002 to 2004) was greater than the yields of ‘Wahoo’ (4030 kg ha-1; Baenziger et al., 2002), ‘Alliance’ (3880 kg ha-1; Baenziger et al., 1995), and ‘Harry’ (4000 kg ha-1; Baenziger et al., 2004b), but was lower than ‘Millennium’ (4180 kg ha-1; Baenziger et al., 2001) and ‘Wesley’ (4210 kg ha-1; Peterson et al., 2001). In its primary area of adaptation (eastern Nebraska), Hallam has yielded 4540 kg ha-1 (five environments), which was greater than Wesley (4150 kg ha-1), Millennium (4250 kg ha-1), Wahoo (3940 kg ha-1), and Alliance (3900 kg ha21). In the Northern Regional Performance Nursery, Hallam ranked 14th of 30 in 2001 (12 environments) and fourth of 25 entries in 2002 (13 environments) and averaged 100 kg ha-1 more grain yield than ‘Nekota’ (Haley et al., 1996). Hallam is not recommended for use in irrigated production systems where other wheat cultivars with superior performance, especially with better straw strength (described below), would be recommended.
Other measurements of performance from comparison trials show that Hallam is moderately early in maturity (142 d after January 1, five environments), about 2.5 d and 1.2 d earlier flowering than Millennium and Wesley, respectively. Hallam is a semidwarf wheat cultivar. Hallam has a medium short coleoptile (46 mm), as expected for a semidwarf wheat cultivar, and is shorter than ‘Goodstreak’ (61 mm; Baenziger et al., 2004a) and slightly longer than semidwarf wheat cultivars such as Harry (36 mm). The mature plant height of Hallam (86 cm) is 3 cm shorter than Millennium and 6 cm taller than Wesley (41 environments). Hallam has moderate straw strength (45% lodged), similar to Wahoo (46% lodged), but worse than Wesley (34% lodged) in those environments (3) where severe lodging was found. The winter hardiness of Hallamis good to very good, similar to ‘Abilene’ (PI 511307) and comparable to other winter wheat cultivars adapted and commonly grown in Nebraska
Antiferromagnetism and phase separation in electronic models for doped transition-metal oxides
We investigate the ground state properties of electronic models for doped
manganites and nickelates. An effective t - J like Hamiltonian is derived from
the case of strong Hund coupling between the conduction electrons and localized
spins by means of the projection technique. An attractive interaction for
conduction electrons and an anti-ferromagnetic coupling of the localized spin
are obtained. A large ratio of the attraction to effective electron hopping,
which is modulated by the spin background, will lead to the phase separation.
The anti-ferromagnetic phase and the phase separation appear in the case of
either high or low density of electrons. The possible relevance of the phase
separation to the charge stripe phase in the manganites and nickelates is
discussed.Comment: 12 pages, ReVTEX, 3 figures. To appear in Phys. Rev. B (RC), (01Oct.,
1998
Spatially resolved Spectro-photometry of M81: Age, Metallicity and Reddening Maps
In this paper, we present a multi-color photometric study of the nearby
spiral galaxy M81, using images obtained with the Beijing Astronomical
Observatory 60/90 cm Schmidt Telescope in 13 intermediate-band filters from
3800 to 10000{\AA}. The observations cover the whole area of M81 with a total
integration of 51 hours from February 1995 to February 1997. This provides a
multi-color map of M81 in pixels of 1\arcsec.7 \times 1\arcsec.7. Using
theoretical stellar population synthesis models, we demonstrate that some BATC
colors and color indices can be used to disentangle the age and metallicity
effect. We compare in detail the observed properties of M81 with the
predictions from population synthesis models and quantify the relative chemical
abundance, age and reddening distributions for different components of M81. We
find that the metallicity of M81 is about with no significant
difference over the whole galaxy. In contrast, an age gradient is found between
stellar populations of the central regions and of the bulge and disk regions of
M81: the stellar population in its central regions is older than 8 Gyr while
the disk stars are considerably younger, Gyr. We also give the
reddening distribution in M81. Some dust lanes are found in the galaxy bulge
region and the reddening in the outer disk is higher than that in the central
regions.Comment: Accepted for publication in AJ (May 2000 issue). 27 pages including 6
figures. Uses AASTeX aasms4 styl
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