Ballistic transport in induced one-dimensional hole systems

We have fabricated and studied a ballistic one-dimensional p-type quantum wire using an undoped AlGaAs/GaAs heterostructure. The absence of modulation doping eliminates remote ionized impurity scattering and allows high mobilities to be achieved over a wide range of hole densities, and in particular, at very low densities where carrier-carrier interactions are strongest. The device exhibits clear quantized conductance plateaus with highly stable gate characteristics. These devices provide opportunities for studying spin-orbit coupling and interaction effects in mesoscopic hole systems in the strong interaction regime where rs > 10.Comment: 6 pages, 4 figures (accepted to Applied Physics Letters

Hamilton's theory of turns revisited

We present a new approach to Hamilton's theory of turns for the groups SO(3) and SU(2) which renders their properties, in particular their composition law, nearly trivial and immediately evident upon inspection. We show that the entire construction can be based on binary rotations rather than mirror reflections.Comment: 7 pages, 4 figure

Division, adjoints, and dualities of bilinear maps

The distributive property can be studied through bilinear maps and various morphisms between these maps. The adjoint-morphisms between bilinear maps establish a complete abelian category with projectives and admits a duality. Thus the adjoint category is not a module category but nevertheless it is suitably familiar. The universal properties have geometric perspectives. For example, products are orthogonal sums. The bilinear division maps are the simple bimaps with respect to nondegenerate adjoint-morphisms. That formalizes the understanding that the atoms of linear geometries are algebraic objects with no zero-divisors. Adjoint-isomorphism coincides with principal isotopism; hence, nonassociative division rings can be studied within this framework. This also corrects an error in an earlier pre-print; see Remark 2.11

Prescribing for young people with Attention Deficit Hyperactivity Disorder in UK primary care: analysis of data from the Clinical Practice Research Datalink

This is the author accepted manuscript. The final version is available from Springer via the DOI in this record.Background Guidance on management of Attention Deficit Hyperactivity Disorder [ADHD] in the UK was issued by the National Institute for Clinical Excellence [NICE] in 2008. No UK study has examined all psychotropic prescribing in young people with ADHD since the introduction of the guidance; this is especially relevant due to the high prevalence of psychiatric comorbidity in this population. Aim To describe primary care prescribing of ADHD and other psychotropic medication for young people with ADHD. Design and setting Analysis of records of patients with an ADHD diagnosis in the UK Clinical Practice Research Datalink from 2005 to 2013. Methods Estimation of the prevalence of prescribing of ADHD and other psychotropic medication over 8 years follow-up for cases aged 10 to 20 years in 2005. Results Of 9,390 ADHD cases, 61.6% (95% confidence interval (CI) = 60.6% to 62.5%) had a prescription at some point for ADHD medication. Prescribing of other psychotropic medication was higher in girls than boys (36.4% versus 22.7%; p<0.001). ADHD prescribing prevalence declined steeply between the ages of 16 and 18 from 37.8% (95% CI 36.6 to 38.9) to 23.7% (95% CI: 22.7 to 24.6%). There was a parallel increase in prescribing of other psychotropics from 3.8% (95% CI: 3.4% to 4.3%) to 6.6% (95% CI 6.0 to 7.3%). Conclusion There is scope to optimise the management of ADHD and psychiatric comorbidities in young people, and a need for sustainable models of ADHD care for young adults, supported by appropriate training and specialist services.National Institute for Health Research (NIHR

Multiple dataset water-quality analyses in the vicinity of an ocean wastewater plume

The White's Point ocean outfall is the method of disposal for approximately 374 million gallons of treated wastewater per day from Los Angeles County. The photosynthetic characteristics and particle distributions have well-defined properties that can be exploited to yield information on transport of the plume, mixing dynamics, and resuspension of bottom sediments during periods of bottom current velocity in excess of ca. 0.1 m/s. This plume of particles serves as a conservative tracer, which was studied using a number of sampling platforms and strategies, including underway sawtooth, or 'tow-yo' sampling, moored arrays of instruments, stationary profiling, and now for the first time with remotely-sensed multispectral color imagery. Research in this area previously focused on examination of the plume as it relates to the local current field and transport of particles, and on the resuspension of bottom sediments during periods of increased currents. In addition, Wu et al elucidated techniques for separating the particle signal into photosynthetic and nonphotosynthetic components, based on the beam attenuation to chlorophyll fluorescence ratio. High-frequency time series measurements of the current field and bio-optical characteristics at a site close to the waste diffusers were also collected. These are being analyzed for the spectral characteristics of the longer-timescale variability, in order to predict particle transport through simple meteorological measurements. With the advent of high spectral and spatial resolution imaging spectrometers such as AVIRIS, it is now possible to construct causal relationships between particle distributions and signature of the upwelled radiance from the surface. The availability of a constant and well-characterized source of material lends itself well to models which predict upwelled radiance from the surface. The availability of a constant and well-characterized source of material lends itself well to models which predict upwelled light as a function of particle distributions, photosynthetic pigments, colored dissolved organic material, and detrital and degradation products of photosynthesis. In addition, the spatial coverage provided by the tow-yo sampling device, combined with the profile measurements of the light field, should facilitate the best inverse modeling attempts possible thus far