Origin and Dynamics of the Mutually Inclined Orbits of Upsilon Andromedae c and d

We evaluate the orbital evolution and several plausible origins scenarios for the mutually inclined orbits of Upsilon Andromedae c and d. These two planets have orbital elements that oscillate with large amplitudes and lie close to the stability boundary. This configuration, and in particular the observed mutual inclination, demands an explanation. The planetary system may be influenced by a nearby low-mass star, Upsilon And B, which could perturb the planetary orbits, but we find it cannot modify two coplanar orbits into the observed mutual inclination of ~30 deg. However, it could incite ejections or collisions between planetary companions that subsequently raise the mutual inclination to >30 deg. Our simulated systems with large mutual inclinations tend to be further from the stability boundary than Upsilon And, but we are able to produce similar systems. We conclude that scattering is a plausible mechanism to explain the observed orbits of Upsilon And c and d, but we cannot determine whether the scattering was caused by instabilities among the planets themselves or by perturbations from Upsilon And B. We also develop a procedure to quantitatively compare numerous properties of the observed system to our numerical models. Although we only implement this procedure to Upsilon And, it may be applied to any exoplanetary system.Comment: 19 pages, 5 figures, accepted to Astrophysical Journa

A literature review on community-acquired methicillin-resistant Staphylococcus aureus in the United States: Clinical information for primary care nurse practitioners

Purpose: To analyze the state of the science of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in the United States to support the integration of current knowledge for primary care nurse practitioners’ (PCNP) practice. Data sources: Published research limited to U.S. studies in MEDLINE, CINAHL, and Cochrane Review from 1950 to the week of September 4, 2008. Investigations were identified through electronic search engines and databases. Manual searches were done of hard copy references in journal articles. Citations and reference lists for English language research studies of CA-MRSA in the United States were reviewed to identify additional research that fit evaluation criteria for this analysis. Conclusions: Until the late 1990s, healthcare-associated MRSA (HA-MRSA) was the predominant cause of serious infections. Recently, CA-MRSA has caused infections in previously healthy nonhospitalized people. Major demographic and epidemiological differences exist between the two types of resistant bacteria; the emergence of CA-MRSA suggests new implications for primary care. Implications for practice: PCNPs will undoubtedly treat MRSA infections and need a comprehensive understanding of the pathogenicity, diagnosis, and management of CA-MRSA to ensure expedient and appropriate treatment. This will help to prevent invasive disease as a result of improperly treated infections.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79099/1/j.1745-7599.2010.00571.x.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/79099/2/JAAN_571_sm_Tables1.pd

First record of verticillium wilt (Verticillium longisporum) in winter oilseed rape in the UK

Verticillium longisporum is an important pathogen of oilseed rape (OSR) and vegetable brassicas in several European countries, but has not been reported previously in the UK (Karapapa et al., 1997; Steventon et al., 2002). In 2007, Verticillium wilt was suspected in UK crops of winter OSR (W-OSR) on cv. Castille in Romney Marsh, Kent and on cv. Barrel near Hereford. At these two locations, 32 and 10% of the plants, respectively, appeared to be affected, but the presence of stem canker may have masked some infections. Symptoms were first seen as the crops began to ripen (seeds green-brown to brown, Growth Stage: 6,4-6,5) and included brown and dark grey vertical bands on the stems from soil level into the branches, and premature ripening of some branches (Fig. 1). Microsclerotia were observed on stem samples collected in the field (Fig. 2), suggesting V. longisporum as the causal agent. Cultures were prepared from field samples by immersing stem pieces in 5% sodium hypochlorite solution for one minute, washing twice in sterile distilled water and plating onto potato dextrose agar containing 25 mg/l streptomycin sulphate. Isolates from three plants per outbreak were identified morphologically as V. longisporum. Mean conidial dimensions (25 spores per isolate) were 8.80-9.65 μm (length) and 2.50-2.85 μm (width) and all isolates produced elongated microsclerotia, characters typical of V. longisporum (Karapapa et al., 1997). The identity was confirmed by PCR using species-specific primers (Steventon et al., 2002) and, as a member of the α sub-group, by direct sequencing of the amplicons from primer pairs ITS4-ITS5 and DB19-DB22 (Collins et al., 2003; 2005). Sequences for isolate 003 from Kent were deposited in GenBank (Accession Nos. HQ702376 and HQ702377). All isolates tested from 2008 and 2009 were identical with previously deposited sequences for European OSR isolates (e.g. AF363992 and AF363246 respectively). Pathogenicity was confirmed by inoculating three OSR cv. Castille seedlings per isolate using the root dip technique with 1 x 106 spores/ml (Karapapa et al., 1997) under heated glasshouse conditions at 19°C. Leaf yellowing and blackening of the leaf veins were found 26 days after inoculation (Fig. 3). Yellowing affecting the three oldest leaves increased for seven to nine days. After five weeks the final mean leaf area affected was 63-78% with no differences between isolates. No leaf yellowing occurred in the controls. After five weeks, V. longisporum was re-isolated from all the inoculated seedlings, but not from the non-inoculated controls. In June 2008, infection of W-OSR crops in different fields on the same farms was found on cv. Es Astrid in Kent (56% incidence) and on cv. Lioness in Hereford (15% incidence). The Kent farm had been growing W-OSR alternating with winter wheat for at least 10 years whilst the Hereford farm had grown W-OSR one year in four. These short rotations of OSR may be contributing to the appearance of this disease. This study confirms the identification of V. longisporum on any host in the UK, through molecular studies and detailed spore measurements that were not reported in an earlier review (Gladders, 2009). This pathogen occurs in several European countries and, since OSR may be traded freely, following a Defra consultation, no statutory plant health action is to be taken

Impact of Teacher and Student Ethnicity on Student Assessments

The purpose of the study was to answer the questions: Do students show greater academic success in English language arts/reading as measured by the Texas Assessment of Knowledge and Skills (TAKS) exam scores in secondary education when their teachers are the same ethinicity? Do students show greater academic success in math as measured by the TAKS exam scores in secondary education when their teachers are the same ethnicity? Minority students' success on the TAKS test was compared to the assessment scores of White students from the 2010-2011, 2011-2012, and 2012-13 school year in thre suburban school districts. This topic has been a subject of discussion since the late 10970s when Cardenas and Cardenas (1977) studied the achievement among minority students and their White peers. The conversation continued through authors such as Takei and Shouse (2008), Hays (2011), Ladson-Billings (2006), Dee (2003, 2005), and Brown (2006). To answer these research questions, a hierarchical multiple regression analysis was conducted on the data collected. Although the study verified the achievement gap between minority students and White students, the study indicated no consistent pattern corroborating that minority students were more successful when taught by teachers of the same ethnicity. In many cases, students learned better with teachers of a different ethnicity. Black students were successful with Hispanic or White teachers, Hispanic students were successful with Black or White teachers, and White students were successful with Black or Hispanic teachers. The TAKS assessment scores were the only data used to support this analysis

Conceptualising Early Career Teachers’ Agency and Accounts of Social Action in Disadvantaged Schools

This article examines the accounts of actions undertaken by Early Career Teachers (ECTs) recently graduated from a social justice-oriented Initial Teacher Education (ITE) program and employed in complex school settings with high levels of student diversity, disadvantage, and poverty. The study drew on theories of teacher agency and agency more broadly to examine the workshadowing observations of the teachers’ practice in classrooms augmented by their reflective accounts in interviews. The study found that the ECTs’ agency, or contextualised social action, can be conceptualised as temporally embedded social engagement directed at addressing their students’ cultural, social and academic needs. The teachers drew on past learnings from their ITE program, committed to future-oriented innovations in teaching, and made in-the-present decisions about actions to resolve emergent contingencies such as resource shortages. We argue that these understandings are usefully enhanced by recognising contingency, consciousness, criticality and creativity as additional features of the teachers’ deliberative programs of action

Exploiting GPUs to investigate an inversion method that retrieves cardiac conductivities from potential measurements

Accurate cardiac bidomain conductivity values are essential for realistic simulation of various cardiac electrophysiological phenomena. A method was previously developed that can determine the conductivities from measurements of potential on a multi-electrode array placed on the surface of the heart. These conductivities, as well as a value for fibre rotation, are determined using a mathematical model and a two-pass process that is based on Tikhonov regularisation. Using simulated potentials, to which noise is added, the inversion method was recently shown to retrieve the intracellular conductivities accurately with up to 15% noise and the extracellular conductivities extremely accurately even with 20% noise. Recent work investigated the sensitivity of the method to the choice of the regularisation parameters. Such a study only became possible due to modifications that were made to the C++ code so that it could run on graphical processing units (GPUs) on the CUDA platform. As the method required the solution of a large number of matrix equations, the highly parallel nature of GPUs was exploited to accelerate execution of the code. Reorganisation of the code and more efficient memory management techniques allowed the data to completely fit in the GPU memory. Comparison between the execution time on the GPU versus the original CPU code shows a speedup of up to 60 times. In the future, the speedup could be further increased with greater use of shared memory, which has a much lower latency (access time) than global memory. References Clayton, R. H., Bernus, O., Cherry, E. M., Dierckx, H., Fenton, F. H., Mirabella, L., Panfilov, A. V., Sachse, F. B., Seemann, G., and Zhang, H. Models of cardiac tissue electrophysiology: Progress, challenges and open questions. Progress in Biophysics and Molecular Biology, 104(1–3):22–48, 2011. doi:10.1016/j.pbiomolbio.2010.05.008 Arthur, R. M. and Geselowitz, D. B. Effect of inhomogeneities on the apparent location and magnitude of a cardiac current dipole source. IEEE Transactions on Biomedical Engineering, 17:141–146, 1970. doi:10.1109/TBME.1970.4502713 Clerc, L. Directional differences of impulse spread in trabecular muscle from mammalian heart. Journal of Physiology, 255:335–346, 1976. http://jp.physoc.org/content/255/2/335 Roberts, D. E., Hersh, L. T., and Scher, A. M. Influence of cardiac fiber orientation on wavefront voltage, conduction velocity and tissue resistivity in the dog. Circ. Res., 44:701–712, 1979. doi:10.1161/01.RES.44.5.701 Roberts, D. E. and Scher, A. M. Effects of tissue anisotropy on extracellular potential fields in canine myocardium in situ. Circ. Res., 50:342–351, 1982. doi:10.1161/01.RES.50.3.342 Hooks, D. A. Myocardial segment-specific model generation for simulating the electrical action of the heart. BioMedical Engineering OnLine, 6(1):21–21, 2007. doi:10.1186/1475-925X-6-21 MacLachlan, M. C., Sundnes, J., and Lines, G. T. Simulation of ST segment changes during subendocardial ischemia using a realistic 3-D cardiac geometry. IEEE Transactions on Biomedical Engineering, 52(5):799–807, 2005. doi:10.1109/TBME.2005.844270 Roth, B. J. Electrical conductivity values used with the bidomain model of cardiac tissue. IEEE Transactions on Biomedical Engineering, 44(4):326–328, April 1997. doi:10.1109/10.563303 Johnston, P. R. and Kilpatrick, D. The effect of conductivity values on ST segment shift in subendocardial ischaemia. IEEE Transactions on Biomedical Engineering, 50(2):150–158, February 2003. doi:10.1109/TBME.2002.807660 Johnston, P. R. Cardiac conductivity values–-a challenge for experimentalists? Noninvasive Functional Source Imaging of the Brain and Heart and 2011 8th International Conference on Bioelectromagnetism (NFSI and ICBEM), pages 39–43, 13-16 May 2011. doi:10.1109/NFSI.2011.5936816 Hooks, D. A. and Trew, M. L. Construction and validation of a plunge electrode array for three-dimensional determination of conductivity in the heart. IEEE Transactions on Biomedical Engineering, 55(2):626–635, 2008. doi:10.1109/TBME.2007.903705 Trew, M. L., Caldwell, B. J., Gamage, T. P. B., Sands, G. B., and Smaill, B. H. Experiment-specific models of ventricular electrical activation: Construction and application. In 30th Annual International IEEE EMBS Conference, pages 137–140, 2008. doi:10.1109/IEMBS.2008.4649109 Caldwell, B. J., Trew, M. L., Sands, G. B., Hooks, D. A., LeGrice, I. J., and Smaill, B. H. Three distinct directions of intramural activation reveal nonuniform side–to–side electrical coupling of ventricular myocytes. Circulation: Arrhythmia and Electropysiology, 2:433–440, 2009. doi:10.1161/CIRCEP.108.830133 Pollard, A. E., Ellis, C. D., and Smith, W. M. Linear electrode arrays for stimulation and recording within cardiac tissue space constants. IEEE Transactions on Biomedical Engineering, 55(4):1408–1414, 2008. doi:10.1109/TBME.2007.912401 Pollard, A. E. and Barr, R. C. A biophysical model for cardiac microimpedance measurements. American Journal of Physiology-Heart and Circulatory Physiology, 298:H1699–H1709, 2010. doi:10.1152/ajpheart.01131.2009 Johnston, B. M. Design of a multi–electrode array to measure cardiac conductivities. ANZIAM Journal, 54:C271–C290, 2013. http://journal.austms.org.au/ojs/index.php/ANZIAMJ/article/viewFile/6278/1694 Johnston, B. M. and Johnston, P. R. A multi-electrode array and inversion technique for retrieving six conductivities from heart potential measurements. Medical and Biological Engineering and Computing, 51(12):1295–1303, 2013. doi:10.1007/s11517-013-1101-2 Johnston, B. M. Using a sensitivity study to facilitate the design of a multi–electrode array to measure six cardiac conductivity values Mathematical Biosciences, 244:40–46, 2013. doi:10.1016/j.mbs.2013.04.003 Plonsey, R. and Barr, R. The four-electrode resistivity technique as applied to cardiac muscle. IEEE Transactions on Biomedical Engineering, 29(7):541–546, 1982. doi:10.1109/TBME.1982.324927 Johnston, B. M., Johnston, P. R., and Kilpatrick, D. A new approach to the determinination of cardiac potential distributions: Application to the analysis of electrode configurations. Mathematical Biosciences, 202(2):288–309, 2006. doi:10.1016/j.mbs.2006.04.004 Johnston, B. M., Johnston, P. R., and Kilpatrick, D. Analysis of electrode configurations for measuring cardiac tissue conductivities and fibre rotation. Annals of Biomedical Engineering, 34(6):986–996, June 2006. doi:10.1007/s10439-006-9098-4 Kuntsevich, A. and Kappel, F. SolvOpt: The solver for Local Nonlinear Optimisation Problems, version 1.1 in C. Technical Report, Institute for Mathematics: Karl–Franzens University of Graz, 1997. http://uni-graz.at/imawww/kuntsevich/solvopt/ps/manual.pd

Generalized software requirements to access thesauri and classification schemes for user-based image collections

This paper describes proposed schemes for describing and indexing two image collections and equirements for the software that would give the end-user access to thesaurus terms and a graphical display of the faceted classification structures of indexing records. Editorial cartoons comprise one collection, dance videos the other

Diffusion Tensor Imaging Findings in Pediatric Patients with Mild Traumatic Brain Injury

Approximately 14% of school age children with sports-related concussions (SRC) remain symptomatic 3 months after injury. Previous studies have used diffusion tensor imaging (DTI) to detect white matter tract changes in regions of interest in symptomatic patients; however data in the pediatric population remains limited. This study was undertaken to determine whether DTI metrics can provide valuable information in pediatric mTBI patients with persistent symptoms