Ray helicity: a geometric invariant for multi-dimensional resonant wave conversion

For a multicomponent wave field propagating into a multidimensional conversion region, the rays are shown to be helical, in general. For a ray-based quantity to have a fundamental physical meaning it must be invariant under two groups of transformations: congruence transformations (which shuffle components of the multi-component wave field) and canonical transformations (which act on the ray phase space). It is shown that for conversion between two waves there is a new invariant not previously discussed: the intrinsic helicity of the ray

A national survey on the patterns of treatment of inflammatory bowel disease in Canada

BACKGROUND: There is a general lack of information on the care of inflammatory bowel disease (IBD) in a broad, geographically diverse, non-clinic population. The purposes of this study were (1) to compare a sample drawn from the membership of a national Crohn's and Colitis Foundation to published clinic-based and population-based IBD samples, (2) to describe current patterns of health care use, and (3) to determine if unexpected variations exist in how and by whom IBD is treated. METHODS: Mailed survey of 4453 members of the Crohn's and Colitis Foundation of Canada. The questionnaire, in members stated language of preference, included items on demographic and disease characteristics, general health behaviors and current and past IBD treatment. Each member received an initial and one reminder mailing. RESULTS: Questionnaires were returned by 1787, 913, and 128 people with Crohn's disease, ulcerative colitis and indeterminate colitis, respectively. At least one operation had been performed on 1159 Crohn's disease patients, with risk increasing with duration of disease. Regional variation in surgical rates in ulcerative colitis patients was identified. 6-Mercaptopurine/Azathioprine was used by 24% of patients with Crohn's disease and 12% of patients with ulcerative colitis (95% CI for the difference: 8.9% – 15%). In patients with Crohn's disease, use was not associated with gender, income or region of residence but was associated with age and markers of disease activity. Infliximab was used by 112 respondents (4%), the majority of whom had Crohn's disease. Variations in infliximab use based on region of residence and income were not seen. Sixty-eight percent of respondents indicated that they depended most on a gastroenterologist for their IBD care. There was significant regional variation in this. However, satisfaction with primary physician did not depend on physician type (for example, gastroenterologist versus general practitioner). CONCLUSION: This study achieved the goal of obtaining a large, geographically diverse sample that is more representative of the general IBD population than a clinic sample would have been. We could find no evidence of significant regional variation in medical treatments due to gender, region of residence or income level. Differences were noted between different age groups, which deserves further attention

Non-traumatic Arm, Neck, and Shoulder Complaints in General Practice: Incidence, Course and Management

Non-traumatic complaints of arm, neck, and shoulder are common and can result in functional limitations in daily life and may sometimes lead to sickness absence. Reported symptoms are e.g. pain, tingling, stiffness, numbness, loss of hand coordination. When seeking medical care for these complaints, the general practitioner (GP) is usually the first person to consult. This thesis studies patients who consult their GP with a new non-traumatic complaint of arm, neck or shoulder, with a focus on incidence, course and management. The incidence study showed that a fulltime GP is consulted about 3 times every week for a new non-traumatic complaint of arm, neck, or shoulder, most frequently located at neck or shoulder. Six months after the first consultation with their GP, 46% of the patients in the cohort study reported no recovery. Next to several complaint specific variables, the psychosocial variables little social support and high score on somatization were predicitve of non-recovery at 6 months. Management upto 6 months after the first consultation most frequently consisted of prescribed analgesics and referral for physiotherapy. Specific and non-specific diagnostic subgroups differed in the frequency that corticosteroid injections were applied, and referrals to physiotherapy and to a medical specialist. In addition variables associated with five common management options within a few weeks after the first consultation were evaluated. Overall, besides diagnosis, most frequently long duration of complaints, more functional limitations but also several GP characteristics were associated with the application of a treatment option in non-traumatic arm, neck and shoulder complaints

Role of defects in the electronic properties of amorphous/crystalline Si interface

The mechanism determining the band alignment of the amorphous/crystalline Si heterostructures is addressed with direct atomistic simulations of the interface performed using a hierarchical combination of various computational schemes ranging from classical model-potential molecular dynamics to ab-initio methods. We found that in coordination defect-free samples the band alignment is almost vanishing and independent on interface details. In defect-rich samples, instead, the band alignment is sizeably different with respect to the defect-free case, but, remarkably, almost independent on the concentration of defects. We rationalize these findings within the theory of semiconductor interfaces.Comment: 4 pages in two-column format, 2 postscript figures include

Inclusive education in the academy: pedagogical and political imperatives in a master’s course

Many universities offer undergraduate and postgraduate courses in inclusive education. There has been much research into the impact of these courses, but little is written about their design. This article focuses on a master’s course in inclusive education in a South African university. The course positions inclusive education as a critical education project and is designed around the four propositions presented by Slee in The Irregular School (2011. Milton Park: Routledge). Using Bernsteinian ideas about pedagogising knowledge, this article accounts for the pedagogical choices made in content selection and course design. The focal questions in the course are described, together with an indication of the range of additional texts that students read. Given that Slee asserts that inclusive education is a political project, and that Allan (2010. “The Inclusive Teacher Educator: Spaces for Civic Engagement.” Discourse: Studies in the Cultural Politics of Education 31 (4): 411–422) urges inclusive teacher educators to reorientate themselves towards civic duty, I argue that producing a pedagogic discourse of inclusive education is a political task that should result in both the teacher educator and the students being oriented towards a critique of existing exclusionary arrangements and an activism that leads to change

<i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties

Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data

Genetic risk and a primary role for cell-mediated immune mechanisms in multiple sclerosis.

Multiple sclerosis is a common disease of the central nervous system in which the interplay between inflammatory and neurodegenerative processes typically results in intermittent neurological disturbance followed by progressive accumulation of disability. Epidemiological studies have shown that genetic factors are primarily responsible for the substantially increased frequency of the disease seen in the relatives of affected individuals, and systematic attempts to identify linkage in multiplex families have confirmed that variation within the major histocompatibility complex (MHC) exerts the greatest individual effect on risk. Modestly powered genome-wide association studies (GWAS) have enabled more than 20 additional risk loci to be identified and have shown that multiple variants exerting modest individual effects have a key role in disease susceptibility. Most of the genetic architecture underlying susceptibility to the disease remains to be defined and is anticipated to require the analysis of sample sizes that are beyond the numbers currently available to individual research groups. In a collaborative GWAS involving 9,772 cases of European descent collected by 23 research groups working in 15 different countries, we have replicated almost all of the previously suggested associations and identified at least a further 29 novel susceptibility loci. Within the MHC we have refined the identity of the HLA-DRB1 risk alleles and confirmed that variation in the HLA-A gene underlies the independent protective effect attributable to the class I region. Immunologically relevant genes are significantly overrepresented among those mapping close to the identified loci and particularly implicate T-helper-cell differentiation in the pathogenesis of multiple sclerosis

Assessing early memories of threat and subordination: Confirmatory factor analyisis of the early life experiences scale for adolescents.

The Early Life Experiences Scale (ELES) is a self-report questionnaire that assesses personal feelings of perceived threat and submissiveness in interactions within family. This paper presents the adaptation and validation of the ELES in Portuguese language for adolescents. The sample was composed of 771 adolescents from community schools with ages between 13 and 18 years old. Along with ELES, participants also answered the Early Memories of Warmth and Safeness Scale and the Positive and Negative Affect Schedule for Children and Adolescents. Confirmatory factor analysis (CFA) was performed to test the factor structure of the ELES and results confirm a three-factor structure, composed by Threat, Submissiveness and Unvalued dimensions. These emotional memories focused on perceived threat, submissiveness and unvalued seem to have a distinct nature. The scale also showed adequate internal consistency, good test-retest reliability and convergent validity with measures of positive emotional memories, positive and negative affect. There were sex differences for threat subscale and age differences for submissiveness subscale. Overall, these findings suggest that the ELES in its Portuguese version for adolescents may be a useful tool for research, educational and clinical contexts with school-aged adolescents