STM and ab initio study of holmium nanowires on a Ge(111) Surface

A nanorod structure has been observed on the Ho/Ge(111) surface using scanning tunneling microscopy (STM). The rods do not require patterning of the surface or defects such as step edges in order to grow as is the case for nanorods on Si(111). At low holmium coverage the nanorods exist as isolated nanostructures while at high coverage they form a periodic 5x1 structure. We propose a structural model for the 5x1 unit cell and show using an ab initio calculation that the STM profile of our model structure compares favorably to that obtained experimentally for both filled and empty states sampling. The calculated local density of states shows that the nanorod is metallic in character.Comment: 4 pages, 12 figures (inc. subfigures). Presented at the the APS March meeting, Baltimore MD, 200

Reshaping graduate outcomes of science students – The contribution of undergraduate research experiences

Today’s science graduates require substantially different skills compared to yesterday’s graduates given the changing nature of modern science. As higher education institutions struggle to reform curricula and pedagogy, undergraduate research experiences (UREs) are increasingly being incorporated to enhance undergraduate science curricula. This study is situated within a traditional Bachelor of Science degree that offers students some voluntary opportunities to participate in UREs. This study explores two graduating science cohorts (n=272), comparing those who did and did not participate in UREs. A survey investigated student perceptions (importance, confidence and improvements) of five graduate outcomes in the context of science: writing skills, communication skills, quantitative skills (QS), teamwork skills and content knowledge. Cross-tabs and a linear discriminant analysis were used to investigate perception change between the two groups. The notable differences in perception scores in this study were consistently higher in QS, perhaps indicative of UREs emphasising the need for such skills in science or from students gaining increased confidence as a result of utilising QS within an authentic context. Our results reveal little difference in other student outcome areas, which raises questions around the role of UREs as a broad strategy for enhancing the achievement of graduate outcomes in science. This study is limited to a single institution and is focused on specific graduate outcomes, so only limited conclusions can be drawn. However, further research to determine the graduate outcomes gained from UREs would benefit the sector, particularly science disciplines, in the changing focus of government policy on student learning outcomes

Testing the APSIM model with data from a phosphorus and nitrogen replenishment experiment on an oxisol in

Abstract An experiment was conducted on an Oxisol near Maseno in western Kenya, to compare the growth of maize crops to inputs of two phosphorus sources. Commercial triple superphosphate (TSP) and Minjingu phosphate rock were applied either at a once-only rate of 250 kg P ha -1 or as five annual inputs of 50 kg P ha -1 . The experiment was carried out over 10 cropping seasons between 1996 and 2000. An additional factor studied was the source of N, either as urea or tithonia biomass-N to supply 60 kg N ha -1 . Both N and P sources were applied only to the crops grown in the long rain season. The APSIM model has been tested against this data set. The effects of P treatments were large in the long rain season, but in the short rain season the inadequate supply of N greatly reduced growth and P effects. The yields of the maize crops were predicted well (r 2 = 0.88) with respect to both the P treatments (as TSP) and the N inputs (as urea). The predicted water, N and P stresses were informative in understanding the contrasting pattern of response observed in the two seasons. The simulation of this long-term experiment shows that the APSIM SoilP module is robust, in as much as it extends the testing of the model to a very different environment where there were both N and P stresses affecting plant growth, and on a very different soil type to where the concepts in the APSIM phosphorus routines were originally developed and tested. Crop production on many soils in western Kenya is limited by both nitrogen (N) and phosphorus (P). The concept of recapitalisation of soil P has focused attention on the use of rock phosphate materials rather than commercial forms of processed fertilisers, and the feasibility of raising soil P through large, one-time application rather than a gradual increase with smaller, but regular inputs . Such strategies have been evaluated in long-term experiments in western Kenya. Probert In this paper, we describe the testing of the APSIM P routines using an experiment that provides suitable data for testing some aspects of the model. The annual rainfall and soil type, especially with regards to its phosphorus sorption properties, ar

Effect of disorder on the vortex-lattice melting transition

We use a three dimensional stacked triangular network of Josephson junctions as a model for the study of vortex structure in the mixed state of high Tc superconductors. We show that the addition of disorder destroys the first order melting transition occurring for clean samples. The melting transition splits in two different (continuous) transitions, ocurring at temperatures Ti and Tp (>Ti). At Ti the perpendicular-to-field superconductivity is lost, and at Tp the parallel-to-field superconductivity is lost. These results agree well with recent experiments in YBaCuO.Comment: 4 pages + 2 figure

The role of the psychologist in the inpatient pain service: development and initial outcomes

© The British Pain Society 2020. Aim: This article describes the development and initial evaluation of introducing a psychologist role within an adult inpatient pain service (IPS) in a large North West of England National Health Service (NHS) trust. Background: The role of a psychologist in the management of outpatient chronic pain has been well documented, but their role within the IPS is less well described and rarely evaluated. We describe the development of a psychologist role within the team and initial service evaluation outcomes. Methods: Following an initial needs assessment, a band 8c psychologist joined the IPS one day per week offering brief one-to-one psychological interventions to people struggling with acute or chronic pain in hospital referred by inpatient pain team. The psychologist had an indirect role offering training, supervision and support to members of the inpatient pain team. Regarding direct patient work, following psychometric screening for pain-related disability and distress, a cognitive behavioural therapy (CBT) approach was applied including identifying unhelpful beliefs about pain, psychoeducation about acute and persistent pain, developing and sharing formulations, skills training including breathing and relaxation exercises and where appropriate, signposting onto an outpatient chronic pain services for further pain self-management advice (e.g. pain management programme. To explore the impact of this direct intervention, a prospective service evaluation with a controlled before and after design was conducted. This compared (a) number of admissions and (b) length-of-stay outcomes in the 12 months following psychometric screening for patients who received psychological input (n = 34, the treatment group) and a sample who did not receive input because of discharge before intervention or non-availability of the psychologist, for example, annual leave (n = 30, control group). Demographic information and summaries of psychometric questionnaires were also analysed. Results: Of the sample of 64 patients, 50 were women, ages ranged from 18–80 years, 72% reported being currently unemployed or off sick from work and on screening and 39% and 48% met criteria for severe depression and pain-related anxiety, respectively. Hospital admissions in the intervention group reduced significantly (by 60%) in the 12 months following screening but increased (by 7%) for the control group (F(1,62) = 7.21, p =.009). Days of stay in hospital reduced significantly more (by 84%) in the intervention group than in the control group (by 41%) (F(1,62) = 8.90, p =.004). Illustrated case studies of brief psychological intervention with three people struggling with pain-related distress are presented. Conclusions: The psychologist became a valuable member of the multi-disciplinary IPS team, offering brief direct and indirect psychological interventions. While a relatively small sample, our prospective service evaluation data suggest brief psychological intervention may contribute to reduced length of stay and hospital admissions for people experiencing pain-related distress in hospital

The phase diagram of high-Tc's: Influence of anisotropy and disorder

We propose a phase diagram for the vortex structure of high temperature superconductors which incorporates the effects of anisotropy and disorder. It is based on numerical simulations using the three-dimensional Josephson junction array model. We support the results with an estimation of the internal energy and configurational entropy of the system. Our results give a unified picture of the behavior of the vortex lattice, covering from the very anysotropic BiSrCaCuO to the less anisotropic YBaCuO, and from the first order melting ocurring in clean samples to the continuous transitions observed in samples with defects.Comment: 8 pages with 7 figure

Vortex structure and resistive transitions in high-Tc superconductors

The nature of the resistive transition for a current applied parallel to the magnetic field in high-Tc materials is investigated by numerical simulation on the three dimensional Josephson junction array model. It is shown by using finite size scaling that for samples with disorder the critical temperature Tp for the c axis resistivity corresponds to a percolation phase transition of vortex lines perpendicularly to the applied field. The value of Tp is higher than the critical temperature for j perpendicular to H, but decreases with the thickness of the sample and with anisotropy. We predict that critical behavior around Tp should reflect in experimentally accessible quantities, as the I-V curves.Comment: 8 pages + 6 figure

Simulation of growth and development of diverse legume species in APSIM

This paper describes the physiological basis and validation of a generic legume model as it applies to 4 species: chickpea (Cicer arietinum L.), mungbean (Vigna radiata (L.) Wilczek), peanut (Arachis hypogaeaL.), and lucerne (Medicago sativa L.). For each species, the key physiological parameters were derived from the literature and our own experimentation. The model was tested on an independent set of experiments, predominantly from the tropics and subtropics of Australia, varying in cultivar, sowing date, water regime (irrigated or dryland), row spacing, and plant population density. The model is an attempt to simulate crop growth and development with satisfactory comprehensiveness, without the necessity of defining a large number of parameters. A generic approach was adopted in recognition of the common underlying physiology and simulation approaches for many legume species. Simulation of grain yield explained 77, 81, and 70% of the variance (RMSD = 31, 98, and 46 g/m2) for mungbean (n = 40, observed mean = 123 g/m2), peanut (n = 30, 421 g/m2), and chickpea (n = 31, 196 g/m2), respectively. Biomass at maturity was simulated less accurately, explaining 64, 76, and 71% of the variance (RMSD = 134, 236, and 125 g/m2) for mungbean, peanut, and chickpea, respectively. RMSD for biomass in lucerne (n = 24) was 85 g/m2 with an R2 of 0.55. Simulation accuracy is similar to that achieved by single-crop models and suggests that the generic approach offers promise for simulating diverse legume species without loss of accuracy or physiological rigour

Modelling nitrogen mineralization from manures: representing quality aspects by varying C:N ratio of sub-pools

The mineralization/immobilization of nitrogen when organic sources are added to soil is represented in many simulation models as the outcome of decomposition of the added material and synthesis of soil organic matter. These models are able to capture the pattern of N release that is attributable to the N concentration of plant materials, or more generally the C:N ratio of the organic input. However, the models are unable to simulate the more complex pattern of N release that has been observed for some animal manures, notably materials that exhibit initial immobilization of N even when the C:N of the material suggests it should mineralize N. The APSIM SoilN module was modified so that the three pools that constitute added organic matter could be specified in terms of both the fraction of carbon in each pool and also their C:N ratios (previously it has been assumed that all pools have the same C:N ratio). It is shown that the revised model is better able to simulate the general patterns on N mineralized that has been reported for various organic sources. By associating the model parameters with measured properties (the pool that decomposes most rapidly equates with water-soluble C and N; the pool that decomposes slowest equates with lignin-C) the model performed better than the unmodified model in simulating the N mineralization from a range of feeds and faecal materials measured in an incubation experimen