21,702 research outputs found
Phosphorus in land-water systems
Analyses were made to obtain information on distribution of different forms of phosphate in different environmental media, including soils, eroding material, and bottom sediment. Major emphasis was placed on determining several forms of inorganic phosphate in each media. Results show that eroding material can transport significant quantities of phosphates from soils
Fano-Kondo interplay in a side-coupled double quantum dot
We investigate low-temperature transport characteristics of a side-coupled
double quantum dot where only one of the dots is directly connected to the
leads. We observe Fano resonances, which arise from interference between
discrete levels in one dot and the Kondo effect, or cotunneling in general, in
the other dot, playing the role of a continuum. The Kondo resonance is
partially suppressed by destructive Fano interference, reflecting novel
Fano-Kondo competition. We also present a theoretical calculation based on the
tight-binding model with slave boson mean field approximation, which
qualitatively reproduces the experimental findings.Comment: 4 pages, 4 figure
Recommended from our members
Guidelines for analysis and reporting of clinical trials in oncology.
When analyzing and reporting the results of clinical trials, investigators should follow a simple approach. The purpose of a trial is to estimate an effect or treatment difference, which if present would have clinical utility when treating new patients. Procedures or methods that do not facilitate precisely and impartially estimating and reporting the treatment effect are likely to mislead investigators. Most often in clinical trials, investigators are interested in estimates of risk ratios (specifically odds or hazard ratios) between the treatment groups or levels of a prognostic factor. These simple ideas suggest that the most useful results from clinical trials will be estimated risk ratios and their confidence limits. Especially in cancer, where disease progression, recurrence, and death are common events following treatment, estimates of risk difference are very relevant. Hypothesis tests and associated P-values, although often (or exclusively) reported, are of lesser utility because they do not fully summarize the data. These recommendations may be seen by some investigators to be contrary to accepted practice. It is true that they are somewhat contrary to common practice but their general acceptance is evident in many journals and presentations by clinical trial methodologists. Despite some disagreement among statisticians regarding the need for adjustment of analyses for imbalanced prognostic factors, it is helpful to see if treatment effects change after accounting for imbalances. When this occurs, it may be of clinical interest. Although we discourage analyses that exclude any patients who meet the eligibility criteria, some circumstances will require that this be done (e.g., when a patient refuses to participate after randomization). Investigators should report, and emphasize as primary, those analyses that include all eligible patients. It is our hope and belief that analysis and reporting of trial results along the guidelines suggested here will result in impartial and useful information for journal readers
Cosmic Chemical Evolution
Numerical simulations of standard cosmological scenarios have now reached the
degree of sophistication required to provide tentative answers to the
fundamental question: Where and when were the heavy elements formed? Averaging
globally, these simulations give a metallicity that increases from 1% of the
solar value at to 20% at present. This conclusion is, in fact,
misleading, as it masks the very strong dependency of metallicity on local
density. At every epoch higher density regions have much higher metallicity
than lower density regions. Moreover, the highest density regions quickly
approach near solar metallicity and then saturate, while more typical regions
slowly catch up. These results are much more consistent with observational data
than the simpler picture (adopted by many) of gradual, quasi-uniform increase
of metallicity with time.Comment: ApJ(Letters) in press, 15 latex pages and 4 figure
Spin-dependent observables in surrogate reactions
Observables emitted from various spin states in compound U nuclei are
investigated to validate usefulness of the surrogate reaction method. It was
found that energy spectrum of cascading -rays and their multiplicities,
spectrum of evaporated neutrons, and mass-distribution of fission fragments
show clear dependence on the spin of decaying nuclei. The present results
indicate that they can be used to infer populated spin distributions which
significantly affect the decay branching ratio of the compound system produced
by the surrogate reactions
Optical Spatial integration methods for ambiguity function generation
A coherent optical spatial integration approach to ambiguity function generation is described. It uses one dimensional acousto-optic Bragg cells as input tranducers in conjunction with a space variant linear phase shifter, a passive optical element, to generate the two dimensional ambiguity function in one exposure. Results of a real time implementation of this system are shown
Strong Magnetization Measured in the Cool Cores of Galaxy Clusters
Tangential discontinuities, seen as X-ray edges known as cold fronts (CFs),
are ubiquitous in cool-core galaxy clusters. We analyze all 17 deprojected CF
thermal profiles found in the literature, including three new CFs we
tentatively identify (in clusters A2204 and 2A0335). We discover small but
significant thermal pressure drops below all nonmerger CFs, and argue that they
arise from strong magnetic fields below and parallel to the discontinuity,
carrying 10%-20% of the pressure. Such magnetization can stabilize the CFs, and
explain the CF-radio minihalo connection.Comment: PRL accepted, additional control tests adde
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