Tracking the policy literacy journey of students in a postgraduate diploma course in disability and rehabilitation studies

Health and/or rehabilitation practitioners have to interact with policy decisions. Ideally, they need to be able to understand policies and to engage with them, however, practitioners are often not aware of policies and of how to engage with them. As a post graduate unit with a mandate to develop programmes that respond to practice needs, this article reports on the development of a policy analysis module as part of the Post Graduate Diploma in Disability and Rehabilitation Studies. In this article we report on the development of the module, the approach taken, and on student responses to the module. The course journey of enrolled students is narrated, highlighting the encouragement of student engagement and peer feedback as key to improved learning and understandings in higher education. Facilitators’ use of didactic approaches that centre students and participatory learning seem equally important for meaningful learning

Guidelines for Signing and Marking of Low-Volume Rural Roads

Existing standards and guidelines for the application of signs and markings are unsuited and inefficient for use on low-volume rural roads (less than 400 A D T ) . T o alleviate this inadequacy, several potentially hazardous situations were evaluated to ascertain actual needs for signs and markings as they relate to economy and safety. These evaluations were based on recent research and on probability of conflict analyses regarding the needs for signing and marking of intersections, horizontal curves, and sections of inadequate passing sight distance.The research revealed that more efficient intersection control can be attained from the careful application of S T O P signs and CROSS R O A D warning signs based on approach speed, sight distance, and combined intersecting volumes. It was found that the treatment of horizontal curves can be made more efficient through the application of more stringent guidelines without adversely affecting safety. Striping of no-passing zones was found to be very inefficient in most instances, as the probability of conflict in these situations is virtually n il; guidelines for alternative treatments are presented. Overall, it was the opinion of the authors that application of guidelines suited to the rural con­text would result in savings in time, money, and frustration on the part of responsible agencies

Spin-density-functional theory of circular and elliptical quantum dots

Using spin-density-functional theory, we study the electronic states of a two-dimensional parabolic quantum dot with up to N=58 electrons. We observe a shell structure for the filling of the dot with electrons. Hund's rule determines the spin configuration of the ground state, but only up to 22 electrons. At specific N, the ground state is degenerate, and a small elliptical deformation of the external potential induces a rotational charge-density-wave (CDW) state. Previously identified spin-density-wave (SDW) states are shown to be artifacts of broken spin symmetry in density-functional theory.Comment: 10 pages, 3 figure

The role of the posterior cerebellum in saccadic adaptation:a transcranial direct current stimulation study

The posterior vermis of the cerebellum is considered to be critically involved in saccadic adaptation. However, recent evidence suggests that the adaptive decrease (backward adaptation) and the adaptive increase (forward adaptation) of saccade amplitude rely on partially separate neural substrates. We investigated whether the posterior cerebellum could be differentially involved in backward and forward adaptation by using transcranial direct current stimulation (TDCS). To do so, participants' saccades were adapted backward or forward while they received anodal, cathodal, or sham TDCS. In two extra groups, subjects underwent a nonadaptation session while receiving anodal or cathodal TDCS to control for the direct effects of TDCS on saccadic execution. Surprisingly, cathodal stimulation tended to increase the extent of both forward and backward adaptations, while anodal TDCS strongly impaired forward adaptation and, to a smaller extent, backward adaptation. Forward adaptation was accompanied by a greater increase in velocity with cathodal stimulation, and reduced duration of change for anodal stimulation. In contrast, the expected velocity decrease in backward adaptation was noticeably weaker with anodal stimulation. Stimulation applied during nonadaptation sessions did not affect saccadic gain, velocity, or duration, demonstrating that the reported effects are not due to direct effects of the stimulation on the generation of eye movements. Our results demonstrate that cerebellar excitability is critical for saccadic adaptation. Based on our results and the growing evidence from studies of vestibulo-ocular reflex and saccadic adaptation, we conclude that the plasticity at the level of the oculomotor vermis is more fundamentally important for forward adaptation than for backward adaptation

Statistical mechanics of RNA folding: importance of alphabet size

We construct a minimalist model of RNA secondary-structure formation and use it to study the mapping from sequence to structure. There are strong, qualitative differences between two-letter and four or six-letter alphabets. With only two kinds of bases, there are many alternate folding configurations, yielding thermodynamically stable ground-states only for a small set of structures of high designability, i.e., total number of associated sequences. In contrast, sequences made from four bases, as found in nature, or six bases have far fewer competing folding configurations, resulting in a much greater average stability of the ground state.Comment: 7 figures; uses revtex

Analysis of stimulant prescriptions and drug-related poisoning risk among persons receiving buprenorphine treatment for opioid use disorder

Importance: Stimulant medication use is common among individuals receiving buprenorphine for opioid use disorder (OUD). Associations between prescription stimulant use and treatment outcomes in this population have been understudied. Objectives: To investigate whether use of prescription stimulants was associated with (1) drug-related poisoning and (2) buprenorphine treatment retention. Design, Setting, and Participants: This retrospective, recurrent-event cohort study with a case-crossover design used a secondary analysis of administrative claims data from IBM MarketScan Commercial and Multi-State Medicaid databases from January 1, 2006, to December 31, 2016. Primary analyses were conducted from March 1 through August 31, 2021. Individuals aged 12 to 64 years with an OUD diagnosis and prescribed buprenorphine who experienced at least 1 drug-related poisoning were included in the analysis. Unit of observation was the person-day. Exposures: Days of active stimulant prescriptions. Main Outcomes and Measures: Primary outcomes were drug-related poisoning and buprenorphine treatment retention. Drug-related poisonings were defined using International Classification of Diseases, Ninth Revision, and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, codes; treatment retention was defined by continuous treatment claims until a 45-day gap was observed. Results: There were 13 778 567 person-days of observation time among 22 946 individuals (mean [SD] age, 32.8 [11.8] years; 50.3% men) who experienced a drug-related poisoning. Stimulant treatment days were associated with 19% increased odds of drug-related poisoning (odds ratio [OR], 1.19 [95% CI, 1.06-1.34]) compared with nontreatment days; buprenorphine treatment days were associated with 38% decreased odds of poisoning (OR, 0.62 [95% CI, 0.59-0.65]). There were no significant interaction effects between use of stimulants and buprenorphine. Stimulant treatment days were associated with decreased odds of attrition from buprenorphine treatment (OR, 0.64 [95% CI, 0.59-0.70]), indicating that stimulants were associated with 36% longer mean exposure to buprenorphine and its concomitant protection. Conclusions and Relevance: Among persons with OUD, use of prescription stimulants was associated with a modest increase in per-day risk of drug-related poisoning, but this risk was offset by the association between stimulant use and improved retention to buprenorphine treatment, which is associated with protection against overdose

Density functional theory of spin-polarized disordered quantum dots

Using density functional theory, we investigate fluctuations of the ground state energy of spin-polarized, disordered quantum dots in the metallic regime. To compare to experiment, we evaluate the distribution of addition energies and find a convolution of the Wigner-Dyson distribution, expected for noniteracting electrons, with a narrower Gaussian distribution due to interactions. The tird moment of the total distribution is independent of interactions, and so is predicted to decrease by a factor of 0.405 upon application of a magnetic field which transforms from the Gaussian orthogonal to the Gaussian unitary ensemble.Comment: 13 pages, 2 figure

Time-Dependent Partition-Free Approach in Resonant Tunneling Systems

An extended Keldysh formalism, well suited to properly take into account the initial correlations, is used in order to deal with the time-dependent current response of a resonant tunneling system. We use a \textit{partition-free} approach by Cini in which the whole system is in equilibrium before an external bias is switched on. No fictitious partitions are used. Besides the steady-state responses one can also calculate physical dynamical responses. In the noninteracting case we clarify under what circumstances a steady-state current develops and compare our result with the one obtained in the partitioned scheme. We prove a Theorem of asymptotic Equivalence between the two schemes for arbitrary time-dependent disturbances. We also show that the steady-state current is independent of the history of the external perturbation (Memory Loss Theorem). In the so called wide-band limit an analytic result for the time-dependent current is obtained. In the interacting case we propose an exact non-equilibrium Green function approach based on Time Dependent Density Functional Theory. The equations are no more difficult than an ordinary Mean Field treatment. We show how the scattering-state scheme by Lang follows from our formulation. An exact formula for the steady-state current of an arbitrary interacting resonant tunneling system is obtained. As an example the time-dependent current response is calculated in the Random Phase Approximation.Comment: final version, 18 pages, 9 figure

Steps in the bacterial flagellar motor

The bacterial flagellar motor is a highly efficient rotary machine used by many bacteria to propel themselves. It has recently been shown that at low speeds its rotation proceeds in steps [Sowa et al. (2005) Nature 437, 916--919]. Here we propose a simple physical model that accounts for this stepping behavior as a random walk in a tilted corrugated potential that combines torque and contact forces. We argue that the absolute angular position of the rotor is crucial for understanding step properties, and show this hypothesis to be consistent with the available data, in particular the observation that backward steps are smaller on average than forward steps. Our model also predicts a sublinear torque-speed relationship at low torque, and a peak in rotor diffusion as a function of torque

Impact of Irradiation on Solvent used in SRS Waste Treatment Processes -9122

ABSTRACT Savannah River Site (SRS) will use a Caustic Side Solvent Extraction (CSSX) process to selectively remove radioactive Cs-137 from the caustic High Level Waste (HLW) salt solutions stored in the large carbon steel waste tanks in the SRS Tank Farm. This HLW resulted from several decades of operations at SRS to produce nuclear materials for the United States Government. The removed Cs-137 will be sent to the Defense Waste Processing Facility (DWPF) where it will be immobilized along with the HLW sludges from the SRS Tank Farm into a borosilicate glass that will be put into permanent disposal. Currently the CSSX process is operating on an interim basis in the Modular Caustic Side Solvent Extraction Unit (MCU) facility. Eventually the process will occur in the full scale Salt Waste Processing Facility (SWPF) currently being built. The organic solvent developed for the process is primarily a mixture of the Isopar ® L (a blend of C 10 -C 12 branched alkanes such as dodecane) and an alkyl aryl polyether added as a Modifier (commonly called Cs-7SB) to enhance the solubility of the extractant which is a calixarene-crown ether. The solvent also includes trioctylamine to mitigate the adverse impact of lipophilic agents on the stripping of the cesium into nitric acid. Since the mixture is primarily organic hydrocarbons, it is expected that radiolysis of the mixture with gamma rays and beta particles from the Cs-137 will produce the flammable gas H 2 and also eventually degrade the solvent. For example, much research has been performed on the radiolysis of the organic solvent used in the tributylphosphate (TPB) extraction process (PUREX process) that has been used at SRS and in many other countries for several decades to separate U and Pu from radioactive U-235 fission products such as Cs-137. [1] The purpose of this study was to investigate the radiolysis of the organic solvent for the CSSX process. Researchers at Savannah River National Laboratory (SRNL) irradiated samples of solvent with Co-60 gamma rays. Prior to the irradiation, the solvent was contacted with the aqueous solutions that will be used in the MCU and SWPF facilities. These were the aqueous caustic salt feed, the scrub solution, and wash water. The rates of radiolytic H 2 production were measured both by determining the composition of the gases produced and by measuring pressures produced during radiolysis. The irradiated solvents were then analyzed by various analytical techniques to assess how much of the Isopar ® L, the Modifier, and the extractant had decomposed