496 research outputs found
Chloride movement in a de-watered saline soil profile
Surface ripping affected the downward movement of water and solutes within a saline dewatered duplex soil profile near Kellerberrin. Prior to ripping, 63% of the total rainfall ended up as runoff and there was little evidence from tensiometric measurements and soil solution samples of significant downward flows of water below a depth of 0.3m. Following ripping to a depth of 0.2m to break a near surface hard layer: runoff was reduced to around 13%; there was some change in soil matrix potential; some leaching of the surface soil occurred; and several preferred water fluxes were intercepted at a depth of 1.5m. These intercepted fluxes were recorded shortly after (<1hr) high intensity rainfall greater than 20mm, suggesting post ripping flow through macropores. The initial chloride storage in the profile was 162t ha-1, approximately 5t ha-1 chloride was leached during the field study (3%). The main leaching mechanism before ripping was runoff (0.5t ha-1). After ripping, flow through macropores and mesopores accounted for 0.5t ha-1 , runoff 0.09t ha-1 with the rest redistributed through the soil matrix
Resonant transmission through an open quantum dot
We have measured the low-temperature transport properties of a quantum dot
formed in a one-dimensional channel. In zero magnetic field this device shows
quantized ballistic conductance plateaus with resonant tunneling peaks in each
transition region between plateaus. Studies of this structure as a function of
applied perpendicular magnetic field and source-drain bias indicate that
resonant structure deriving from tightly bound states is split by Coulomb
charging at zero magnetic field.Comment: To be published in Phys. Rev. B (1997). 8 LaTex pages with 5 figure
Multiband tight-binding theory of disordered ABC semiconductor quantum dots: Application to the optical properties of alloyed CdZnSe nanocrystals
Zero-dimensional nanocrystals, as obtained by chemical synthesis, offer a
broad range of applications, as their spectrum and thus their excitation gap
can be tailored by variation of their size. Additionally, nanocrystals of the
type ABC can be realized by alloying of two pure compound semiconductor
materials AC and BC, which allows for a continuous tuning of their absorption
and emission spectrum with the concentration x. We use the single-particle
energies and wave functions calculated from a multiband sp^3 empirical
tight-binding model in combination with the configuration interaction scheme to
calculate the optical properties of CdZnSe nanocrystals with a spherical shape.
In contrast to common mean-field approaches like the virtual crystal
approximation (VCA), we treat the disorder on a microscopic level by taking
into account a finite number of realizations for each size and concentration.
We then compare the results for the optical properties with recent experimental
data and calculate the optical bowing coefficient for further sizes
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Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry
Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI-APi-TOF (Chemical Ionization-Atmospheric Pressure interface-Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI-APi-TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4-H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self-contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit
Relations between Financing and Output in the Not-for-Profit Hospital
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68639/2/10.1177_107755878804500204.pd
Domestic Violence and Health Care: Opening Pandora¿s Box ¿ Challenges and Dilemmas
In this article we take a critical stance toward the rational progressive narrative
surrounding the integration of domestic violence within health care. Whilst changes in
recent UK policy and practice have resulted in several tangible benefits, it is argued that
there may be hidden dilemmas and challenges. We suggest that the medical model of care
and its discursive practices position women as individually accountable for domestic
violence-related symptoms and injuries. This may not only be ineffective in terms of
service provision but could also have the potential to reduce the political significance of
domestic violence as an issue of concern for all women. Furthermore, it is argued that the
use of specific metaphors enables practitioners to distance themselves from interactions
that may prove to be less comfortable and provide less than certain outcomes. Our analysis
explores the possibilities for change that might currently be available. This would
appear to involve a consideration of alternative discourses and the reformulation of power
relations and subject positions in health care
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