4,888 research outputs found
The local convexity of solving systems of quadratic equations
Full text linkThis paper considers the recovery of a rank positive semidefinite matrix
from scalar measurements of the form (i.e., quadratic measurements of ). Such problems arise
in a variety of applications, including covariance sketching of
high-dimensional data streams, quadratic regression, quantum state tomography,
among others. A natural approach to this problem is to minimize the loss
function which has an entire manifold of
solutions given by where is the
orthogonal group of orthogonal matrices; this is {\it non-convex}
in the matrix , but methods like gradient descent are simple and
easy to implement (as compared to semidefinite relaxation approaches).
In this paper we show that once we have samples from
isotropic gaussian , with high probability {\em (a)} this function admits
a dimension-independent region of {\em local strong convexity} on lines
perpendicular to the solution manifold, and {\em (b)} with an additional
polynomial factor of samples, a simple spectral initialization will land
within the region of convexity with high probability. Together, this implies
that gradient descent with initialization (but no re-sampling) will converge
linearly to the correct , up to an orthogonal transformation. We believe
that this general technique (local convexity reachable by spectral
initialization) should prove applicable to a broader class of nonconvex
optimization problems.Comment: 36 pages, 3 figure
Spreading the Green and Sharing the Wealth
Get PDFExamines the effects and benefits of trees for the urban environment, and looks at recent studies that have attempted to define the benefits of urban trees. Discusses the implications of trees for city planning
Ethnicity and the Mental Health Act 1983
Get PDFBackground Black and minority ethnic (BME) patients are disproportionately detained under the Mental Health Act 1983. There has been no systematic exploration of differences within and between ethnic groups, nor of the explanations put forward for this excess.
Aims To systematically review detention and ethnicity, with meta-analyses of detention rates for BME groups, and to explore the explanations offered for ethnic differences in detention rates.
Method Literature search and meta-analysis. Explanations offered were categorised, supporting literature was accessed and the strength of the evidence evaluated.
Results In all, 49 studies met inclusion criteria; of these, 19 were included in the meta-analyses. Compared with White patients, Black patients were 3.83 times, BME patients 3.35 times and Asian patients 2.06 times more likely to be detained. The most common explanations related to misdiagnosis and discrimination against BME patients, higher incidence of psychosis and differences in illness expression. Many explanations, including that of racism within mental health services, were not supported by clear evidence.
Conclusions Although BME status predicts psychiatric detention in the UK, most explanations offered for the excess detention of BME patients are largely unsupported
Advancing impact assessments of non-native species: strategies for strengthening the evidence-base
Get PDFThe numbers and impacts of non-native species (NNS) continue to grow. Multiple ranking protocols have been developed to identify and manage the most damaging species. However, existing protocols differ considerably in the type of impact they consider, the way evidence of impacts is included and scored, and in the way the precautionary principle is applied. These differences may lead to inconsistent impact assessments. Since these protocols are considered a main policy tool to promote mitigation efforts, such inconsistencies are undesirable, as they can affect our ability to reliably identify the most damaging NNS, and can erode public support for NNS management. Here we propose a broadly applicable framework for building a transparent NNS impact evidence base. First, we advise to separate the collection of evidence of impacts from the act of scoring the severity of these impacts. Second, we propose to map the collected evidence along a set of distinguishing criteria: where it is published, which methodological approach was used to obtain it, the relevance of the geographical area from which it originates, and the direction of the impact. This procedure produces a transparent and reproducible evidence base which can subsequently be used for different scoring protocols, and which should be made public. Finally, we argue that the precautionary principle should only be used at the risk management stage. Conditional upon the evidence presented in an impact assessment, decision-makers may use the precautionary principle for NNS management under scientific uncertainty regarding the likelihood and magnitude of NNS impacts. Our framework paves the way for an improved application of impact assessments protocols, reducing inconsistencies and ultimately enabling more effective NNS management
Behind \u27Loving Reading\u27: Reading Behavior in Early Adolescents
Get PDFWhite, Rachel. “Behind ‘Loving Reading’: Reading Behavior in Early Adolescents” (2020).
The research question addressed in this study was: what is the lived experience of loving reading for middle school students? Topics explored in the review included loving reading in popular understanding, reading motivation, reading identity, reading volume and reading in the home. The review also included an overview of affective reading assessments and qualitative understandings of reading attitude. The qualitative research of this study employed the interpretivist paradigm and consisted of interviews with six middle school-aged participants. In the interviews, participants discussed their reading identity, reading habits, reading efficacy, reading motivation, reading future and finally, their love of reading. The results were determined using inductive coding and analysis. Findings suggested that there was little correlation between self-reporting loving reading and habitual leisure reading. Participants who reported loving reading often read in different ways and for different reasons. Some participants read out of a sense of competition, some read out of a sense of obligation and some read to escape into stories. Participants measured their own reading ability almost entirely with standardized testing, not reading habits or enjoyment of reading. Ultimately, the study suggests that students can reflect more deeply discussing reading future and reading motivation than discussing loving reading. The study calls on teachers to interrogate the ways that their students internalize standardized test achievements, especially considering the bias present in these tests. Limitations, implications, and recommendations for future research are discussed
Perceived Parental Characteristics And Neighborhood Support: How Do They Relate To Adolescents\u27 Externalizing Behavior Problem
Get PDFExternalizing behavior problems are related to many problematic outcomes for children and adolescents in their home, school, and community settings. Given the ramifications of difficulties related to externalizing behavior problems, the present study examines the relationships among adolescents\u27 externalizing behavior problems, characteristics of adolescents\u27 families, and their perceived neighborhood support in a sample of adolescents who are in the Sixth through Eighth Grades. As part of this study, adolescents were assessed one time in their school setting with a set of brief questionnaires. In particular, adolescents completed measures assessing their levels of externalizing behavior problems, characteristics of their families, their perceptions of neighborhood support and of their teachers, and their ratings of their own acculturation. Results suggest that, although a moderation relationship does not exist between parental warmth, neighborhood support, and the development of externalizing behavior problems, variables such as maternal warmth, overall parental emotional support, and overall neighborhood support are important predictors of the development of externalizing behavior problems. Further regression analyses reveal that, in addition to neighborhood and parental characteristics, adolescents\u27 perceived social acceptance and global self-worth are significant predictors of adolescents\u27 externalizing behavior problems. In conclusion, when identifying adolescents who are at risk for the development of externalizing behavior problems, an ecological conceptualization encompassing culture, community, and home environments can be helpful
Assessing Gastropods as Parasite Vectors on Small Ruminant Farms
Get PDFAn animal health challenge that many small ruminant producers face is the impact of parasites on production, such as weight loss, reproductive problems, and product yield. The nematode, Parelaphostrongylus tenuis (meningeal worm) can cause severe neurologic symptoms and death in small ruminants. This “phantom parasite” does not have a premortem diagnostic test to detect it, thus the level of incidence in livestock is unknown. Because of this, prevention is the best option to limit incidence, though no research on P. tenuis risk factors to livestock naturally on grazing pastures has been explored. This work aimed to investigate the transmission risk factors of P. tenuis through the intermediate hosts, terrestrial gastropods (snails and slugs) and to explore methods of mitigating risk on a pasture-wide scale.
Over two years, collections and surveys of gastropods were held on six small ruminant farms. This study found that 1% of gastropods living on pastures carry P. tenuis. An in-depth analysis of gastropod intermediate hosts showed a variety of helminths in addition to P. tenuis, including Muellerius capillaris or sheep/ goat lungworm. Snail characteristics, such as shell size, and seasonality on the pasture were correlated with P. tenuis larvae in infected snails.
To investigate methods of controlling high abundances of gastropods on pasture, an integrated pest management approach was explored through an on-farm case study. Pastured poultry, using chickens, and mowing were both found to be successful practices for mitigating snail populations on pastures. However, in plots intentionally allowed to regrow, snail populations quickly rebounded, suggesting that mowing is a practice that may need to be maintained to be effective.
The knowledge, attitudes, and management practices were examined by stakeholders to determine risk perceptions of P. tenuis and other parasites. The farmers involved with this study and veterinarians reported changes in knowledge after learning about study results, and voiced challenges and needs based around animal health education and information gathering.
These data provide insight into the factors of risk and risk-reduction of P. tenuis to small ruminants on grazing space. Farmers and managers may consider these practical methods for animal health improvement and prevention
British Asian families and the use of child and adolescent mental health services: a qualitative study of a hard to reach group
Get PDFWe explored attitudes to and experiences of Child and Adolescent Mental Health Services (CAMHS) among families of South Asian origin who are underrepresented as service-users in an area of a Scottish city with a high concentration of people of South Asian origin. Six community focus groups were conducted, followed by semi-structured interviews with families who had used CAMHS and with CAMHS professionals involved in those families’ cases. Lastly, parents of children who had problems usually referred to CAMHS but who had not used the service were interviewed. Qualitative analysis of transcripts and notes was undertaken using thematic and logical methods.
Participants consisted of 35 adults who identified themselves as Asian and had children; 7 parents and/or the young service users him-herself; 7 health care professionals involved in the young person's care plus 5 carers of 6 young people who had not been referred to CAMHS, despite having suitable problems.
Focus groups identified the stigma of mental illness and the fear of gossip as strong disincentives to use CAMHS. Families who had been in contact with CAMHS sought to minimise the stigma they suffered by emphasising that mental illness was not madness and could be cured. Families whose children had complex emotional and behavioural problems said that discrimination by health, education and social care professionals exacerbated their child's difficulties. Families of children with severe and enduring mental illness described tolerating culturally inappropriate services. Fear of gossip about children's ‘madness’ constituted a major barrier to service use for Asian families in this city. Given the widespread nature of the concern over the stigma of children's mental illness, it should be considered in designing culturally competent services for children's mental health
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