3,978 research outputs found
On Large-Scale Graph Generation with Validation of Diverse Triangle Statistics at Edges and Vertices
Researchers developing implementations of distributed graph analytic
algorithms require graph generators that yield graphs sharing the challenging
characteristics of real-world graphs (small-world, scale-free, heavy-tailed
degree distribution) with efficiently calculable ground-truth solutions to the
desired output. Reproducibility for current generators used in benchmarking are
somewhat lacking in this respect due to their randomness: the output of a
desired graph analytic can only be compared to expected values and not exact
ground truth. Nonstochastic Kronecker product graphs meet these design criteria
for several graph analytics. Here we show that many flavors of triangle
participation can be cheaply calculated while generating a Kronecker product
graph. Given two medium-sized scale-free graphs with adjacency matrices and
, their Kronecker product graph has adjacency matrix . Such
graphs are highly compressible: edges are represented in memory and can be built in a distributed setting from
small data structures, making them easy to share in compressed form. Many
interesting graph calculations have worst-case complexity bounds and often these are reduced to
for Kronecker product graphs, when a Kronecker formula can be derived yielding
the sought calculation on in terms of related calculations on and .
We focus on deriving formulas for triangle participation at vertices, , a vector storing the number of triangles that every vertex is involved
in, and triangle participation at edges, , a sparse matrix storing
the number of triangles at every edge.Comment: 10 pages, 7 figures, IEEE IPDPS Graph Algorithms Building Block
2015 ACVIM Small Animal Consensus Statement on Seizure Management in Dogs
This report represents a scientific and working clinical consensus statement on seizure management in dogs based on current literature and clinical expertise. The goal was to establish guidelines for a predetermined, concise, and logical sequential approach to chronic seizure management starting with seizure identification and diagnosis (not included in this report), reviewing decision‐making, treatment strategies, focusing on issues related to chronic antiepileptic drug treatment response and monitoring, and guidelines to enhance patient response and quality of life. Ultimately, we hope to provide a foundation for ongoing and future clinical epilepsy research in veterinary medicine
The redshift evolution of bias and baryonic matter distribution
We study the distribution of baryonic and luminous matter within the
framework of a hierarchical scenario. Using an analytical model for structure
formation which has already been checked against observations for galaxies,
Lyman- clouds, clusters and reionization processes, we present its
predictions for the bias of these objects. We describe its dependence on the
luminosity (for galaxies or quasars) or the column density (for Lyman-
absorbers) of the considered objects. We also study its redshift evolution,
which can exhibit an intricate behaviour. These astrophysical objects do not
trace the dark matter density field, the Lyman- forest clouds being
undercorrelated and the bright galaxies overcorrelated, while the intermediate
class of Lyman-limit systems is seen to sample the matter field quite well.
We also present the distribution of baryonic matter over these various
objects. We show that light does not trace baryonic mass, since bright galaxies
which contain most of the stars only form a small fraction of the mass
associated with virialized and cooled halos. We consider two cosmologies: a
critical density universe and an open universe. In both cases, our results
agree with observations and show that hierarchical scenarios provide a good
model for structure formation and can describe a wide range of objects which
spans at least the seven orders of magnitude in mass for which data exist. More
detailed observations, in particular of the clustering evolution of galaxies,
will constrain the astrophysical models involved.Comment: 13 pages, final version published in A&
Prevalence and Predictors of Vitamin D Insufficiency in Children: A Great Britain Population Based Study
Objectives
To evaluate the prevalence and predictors of vitamin D insufficiency (VDI) in children In Great Britain.
Design
A nationally representative cross-sectional study survey of children (1102) aged 4–18 years (999 white, 570 male) living in private households (January 1997–1998). Interventions provided information about dietary habits, physical activity, socio-demographics, and blood sample. Outcome measures were vitamin D insufficiency (<50 nmol/L).
Results
Vitamin D levels (mean = 62.1 nmol/L, 95%CI 60.4–63.7) were insufficient in 35%, and decreased with age in both sexes (p<0.001). Young People living between 53–59 degrees latitude had lower levels (compared with 50–53 degrees, p = 0.045). Dietary intake and gender had no effect on vitamin D status. A logistic regression model showed increased risk of VDI in the following: adolescents (14–18 years old), odds ratio (OR) = 3.6 (95%CI 1.8–7.2) compared with younger children (4–8 years); non white children (OR = 37 [95%CI 15–90]); blood levels taken December-May (OR = 6.5 [95%CI 4.3–10.1]); on income support (OR = 2.2 [95%CI 1.3–3.9]); not taking vitamin D supplementation (OR = 3.7 [95%CI 1.4–9.8]); being overweight (OR 1.6 [95%CI 1.0–2.5]); <1/2 hour outdoor exercise/day/week (OR = 1.5 [95%CI 1.0–2.3]); watched >2.5 hours of TV/day/week (OR = 1.6[95%CI 1.0–2.4]).
Conclusion
We confirm a previously under-recognised risk of VDI in adolescents. The marked higher risk for VDI in non-white children suggests they should be targeted in any preventative strategies. The association of higher risk of VDI among children who exercised less outdoors, watched more TV and were overweight highlights potentially modifiable risk factors. Clearer guidelines and an increased awareness especially in adolescents are needed, as there are no recommendations for vitamin D supplementation in older children
A Case of Cutaneous Side Effect of Methotrexate Mimicking Behçet's Disease
Methotrexate (MTX) is an antimetabolite which interferes with DNA synthesis, and it is used for the treatment of moderate to severe psoriasis, atopic dermatitis and a wide variety of cutaneous diseases. Although many adverse effects of MTX, including cutaneous ulcerations, have been documented, multifocal mucosal ulceration mimicking Behçet's disease has not been reported. In our case, a 63-year-old female presented with oral, vaginal ulcer and multiple purpuric patches on both legs. Considering patient's clinical course and histopathologic findings, we presumed that these reactions may be the side effect of MTX administered for treatment of necrotizing scleritis. Herein we report the cutaneous side effect of MTX that manifested clinically like Behçet's disease
The mass assembly of galaxy groups and the evolution of the magnitude gap
We investigate the assembly of groups and clusters of galaxies using the
Millennium dark matter simulation and the associated gas simulations and
semi-analytic catalogues of galaxies. In particular, in order to find an
observable quantity that could be used to identify early-formed groups, we
study the development of the difference in magnitude between their brightest
galaxies to assess the use of magnitude gaps as possible indicators. We select
galaxy groups and clusters at redshift z=1 with dark matter halo mass M(R200) >
1E13/h Msun, and trace their properties until the present time (z=0). We
consider only the systems with X-ray luminosity L_X> 0.25E42/h^2 erg/s at z=0.
While it is true that a large magnitude gap between the two brightest galaxies
of a particular group often indicates that a large fraction of its mass was
assembled at an early epoch, it is not a necessary condition. More than 90% of
fossil groups defined on the basis of their magnitude gaps (at any epoch
between 0<z<1) cease to be fossils within 4 Gyr, mostly because other massive
galaxies are assembled within their cores, even though most of the mass in
their haloes might have been assembled at early times. We show that, compared
to the conventional definition of fossil galaxy groups based on the magnitude
gap Delta m(12)> 2 (in the R-band, within 0.5R200 of the centre of the group),
an alternative criterion Delta m(14)>2.5 (within the same radius) finds 50%
more early-formed systems, and those that on average retain their fossil phase
longer. However, the conventional criterion performs marginally better at
finding early-formed groups at the high-mass end of groups. Nevertheless, both
criteria fail to identify a majority of the early-formed systems.Comment: 16 pages, 11 figures, 2 tables. Accepted for publication in MNRA
Development and validation of the BRIGHTLIGHT Survey, a patient-reported experience measure for young people with cancer
BACKGROUND: Patient experience is increasingly used as an indicator of high quality care in addition to more traditional clinical end-points. Surveys are generally accepted as appropriate methodology to capture patient experience. No validated patient experience surveys exist specifically for adolescents and young adults (AYA) aged 13-24 years at diagnosis with cancer. This paper describes early work undertaken to develop and validate a descriptive patient experience survey for AYA with cancer that encompasses both their cancer experience and age-related issues. We aimed to develop, with young people, an experience survey meaningful and relevant to AYA to be used in a longitudinal cohort study (BRIGHTLIGHT), ensuring high levels of acceptability to maximise study retention. METHODS: A three-stage approach was employed: Stage 1 involved developing a conceptual framework, conducting literature/Internet searches and establishing content validity of the survey; Stage 2 confirmed the acceptability of methods of administration and consisted of four focus groups involving 11 young people (14-25 years), three parents and two siblings; and Stage 3 established survey comprehension through telephone-administered cognitive interviews with a convenience sample of 23 young people aged 14-24 years. RESULT: Stage 1: Two-hundred and thirty eight questions were developed from qualitative reports of young people's cancer and treatment-related experience. Stage 2: The focus groups identified three core themes: (i) issues directly affecting young people, e.g. impact of treatment-related fatigue on ability to complete survey; (ii) issues relevant to the actual survey, e.g. ability to answer questions anonymously; (iii) administration issues, e.g. confusing format in some supporting documents. Stage 3: Cognitive interviews indicated high levels of comprehension requiring minor survey amendments. CONCLUSION: Collaborating with young people with cancer has enabled a survey of to be developed that is both meaningful to young people but also examines patient experience and outcomes associated with specialist cancer care. Engagement of young people throughout the survey development has ensured the content appropriately reflects their experience and is easily understood. The BRIGHTLIGHT survey was developed for a specific research project but has the potential to be used as a TYA cancer survey to assess patient experience and the care they receive
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