9,197 research outputs found
Kinks: Fingerprints of strong electronic correlations
The textbook knowledge of solid state physics is that the electronic specific
heat shows a linear temperature dependence with the leading corrections being a
cubic term due to phonons and a cubic-logarithmic term due to the interaction
of electrons with bosons. We have shown that this longstanding conception needs
to be supplemented since the generic behavior of the low-temperature electronic
specific heat includes a kink if the electrons are sufficiently strongly
correlatedComment: 4 pages, 1 figure, ICM 2009 conference proceedings (to appear in
Journal of Physics: Conference Series
TRAP CROP RADISH: A SUSTAINABLE ALTERNATIVE FOR NEMATICIDE IN SUGAR BEETS
Chemical treatment of nematodes in sugar beets can be very costly ($190 per acre), and hazardous, representing significant environmental risks to air, water and human health. Substituting trap crop radish for chemicals, represents a win-win case of sustainable pest control, yielding environmental benefits, higher profit and reduced risk.Crop Production/Industries,
In-plane gate single-electron transistor in Ga[Al]As fabricated by scanning probe lithography
A single-electron transistor has been realized in a Ga[Al]As heterostructure
by oxidizing lines in the GaAs cap layer with an atomic force microscope. The
oxide lines define the boundaries of the quantum dot, the in-plane gate
electrodes, and the contacts of the dot to source and drain. Both the number of
electrons in the dot as well as its coupling to the leads can be tuned with an
additional, homogeneous top gate electrode. Pronounced Coulomb blockade
oscillations are observed as a function of voltages applied to different gates.
We find that, for positive top-gate voltages, the lithographic pattern is
transferred with high accuracy to the electron gas. Furthermore, the dot shape
does not change significantly when in-plane voltages are tuned.Comment: 4 pages, 3 figure
From infinite to two dimensions through the functional renormalization group
We present a novel scheme for an unbiased and non-perturbative treatment of
strongly correlated fermions. The proposed approach combines two of the most
successful many-body methods, i.e., the dynamical mean field theory (DMFT) and
the functional renormalization group (fRG). Physically, this allows for a
systematic inclusion of non-local correlations via the flow equations of the
fRG, after the local correlations are taken into account non-perturbatively by
the DMFT. To demonstrate the feasibility of the approach, we present numerical
results for the two-dimensional Hubbard model at half-filling.Comment: 5 pages, 4 figure
ECONOMICS OF VARIABLE RATE NEMATICIDE FOR SUGAR BEETS
The benefit of applying fumigant for control of the sugar beet nematode on a variable versus uniform rate basis is examined. Compared to fumigating an entire filed at a constant full-label rate, varialbe rate application provides a savings ranging from 69/ac (lightly infested field).Crop Production/Industries,
The Cerium volume collapse: Results from the LDA+DMFT approach
The merger of density-functional theory in the local density approximation
(LDA) and many-body dynamical mean field theory (DMFT) allows for an ab initio
calculation of Ce including the inherent 4f electronic correlations. We solve
the DMFT equations by the quantum Monte Carlo (QMC) technique and calculate the
Ce energy, spectrum, and double occupancy as a function of volume. At low
temperatures, the correlation energy exhibits an anomalous region of negative
curvature which drives the system towards a thermodynamic instability, i.e.,
the -to- volume collapse, consistent with experiment. The
connection of the energetic with the spectral evolution shows that the physical
origin of the energy anomaly and, thus, the volume collapse is the appearance
of a quasiparticle resonance in the 4f-spectrum which is accompanied by a rapid
growth in the double occupancy.Comment: 4 pages, 3 figure
Rubidium spacecraft atomic timing system Final report
Rubidium 87 atomic time and frequency reference system for manned space fligh
Environmental pollutants from the Scott and Shackleton expeditions during the ‘Heroic Age’ of Antarctic exploration
Early explorers to Antarctica built wooden huts and brought huge quantities of supplies and equipment to support their geographical and scientific studies for several years. When the expeditions ended and relief ships arrived, a rapid exodus frequently allowed only essential items to be taken north. The huts and thousands of items were left behind. Fuel depots with unused containers of petroleum products, asbestos materials, and diverse chemicals were also left at the huts. This investigation found high concentrations of polyaromatic hydrocarbons in soils under and around the historic fuel depots, including anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, chrysene, fluorene, and pyrene, as well as benzo[a]anthracene, benzo[a]pyrene, and fluoranthene, which are recognized carcinogens. Asbestos materials within the huts have been identified and extensive amounts of fragmented asbestos were found littering the ground around the Cape Evans hut. These materials are continually abraded and fragmented as tourists walk over them and the coarse scoria breaks and grinds down the materials. A chemical spill, within the Cape Evans hut, apparently from caustic substances from one of the scientific experiments, has caused an unusual deterioration and defibration on affected woods. Although these areas are important historic sites protected by international treaties, the hazardous waste materials left by the early explorers should be removed and remedial action taken to restore the site to as pristine a condition as possible. Recommendations are discussed for international efforts to study and clean up these areas, where the earliest environmental pollution in Antarctica was produced
T cell receptor specificity is critical for the development of epidermal gammadelta T cells.
A particular feature of gammadelta T cell biology is that cells expressing T cell receptor (TCR) using specific Vgamma/Vdelta segments are localized in distinct epithelial sites, e.g., in mouse epidermis nearly all gammadelta T cells express Vgamma3/Vdelta1. These cells, referred to as dendritic epidermal T cells (DETC) originate from fetal Vgamma3+ thymocytes. The role of gammadelta TCR specificity in DETC's migration/localization to the skin has remained controversial. To address this issue we have generated transgenic (Tg) mice expressing a TCR delta chain (Vdelta6.3-Ddelta1-Ddelta2-Jdelta1-Cdelta), which can pair with Vgamma3 in fetal thymocytes but is not normally expressed by DETC. In wild-type (wt) Vdelta6.3Tg mice DETC were present and virtually all of them express Vdelta6.3. However, DETC were absent in TCR-delta(-/-) Vdelta6.3Tg mice, despite the fact that Vdelta6.3Tg gammadelta T cells were present in normal numbers in other lymphoid and nonlymphoid tissues. In wt Vdelta6.3Tg mice, a high proportion of in-frame Vdelta1 transcripts were found in DETC, suggesting that the expression of an endogenous TCR-delta (most probably Vdelta1) was required for the development of Vdelta6.3+ epidermal gammadelta T cells. Collectively our data demonstrate that TCR specificity is essential for the development of gammadelta T cells in the epidermis. Moreover, they show that the TCR-delta locus is not allelically excluded
Prescribed Burning Based on Range Condition in the Okavango Delta Ramsar Site in Botswana, Africa
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