Parallel structurally-symmetric sparse matrix-vector products on multi-core processors

We consider the problem of developing an efficient multi-threaded implementation of the matrix-vector multiplication algorithm for sparse matrices with structural symmetry. Matrices are stored using the compressed sparse row-column format (CSRC), designed for profiting from the symmetric non-zero pattern observed in global finite element matrices. Unlike classical compressed storage formats, performing the sparse matrix-vector product using the CSRC requires thread-safe access to the destination vector. To avoid race conditions, we have implemented two partitioning strategies. In the first one, each thread allocates an array for storing its contributions, which are later combined in an accumulation step. We analyze how to perform this accumulation in four different ways. The second strategy employs a coloring algorithm for grouping rows that can be concurrently processed by threads. Our results indicate that, although incurring an increase in the working set size, the former approach leads to the best performance improvements for most matrices.Comment: 17 pages, 17 figures, reviewed related work section, fixed typo

Effects of atomic short-range order on the properties of perovskite alloys in their morphotropic phase boundary

The effects of atomic short-range order on the properties of Pb(Zr_{1-x}Ti_x)O_3 alloy in its morphotropic phase boundary (MPB) are predicted by combining first-principles-based methods and annealing techniques. Clustering is found to lead to a compositional expansion of this boundary, while the association of unlike atoms yields a contraction of this region. Atomic short-range order can thus drastically affect properties of perovskite alloys in their MPB, by inducing phase transitions. Microscopic mechanisms responsible for these effects are revealed and discussed.Comment: 4 pages, with 2 postscript figures embedded. Uses REVTEX4 and graphicx macro

Simulations of satellite Doppler wind observations

This study will involve two objectives: (1) to develop, through computer simulations, optimal satellite-based sensor scanning techniques for direct measurement of tropospheric winds on the meso- and synoptic scales; and (2) to construct simulations of remotely measured wind fields for assessing impact of such fields on the diagnosis and prognosis of atmospheric phenomena through the use of Observing System Simulation Experiments (OSSE). Using the LAWS Simulation Model (LSM), various global coverage scenarios have been investigated as part of an effort to define the optimal orbit, configuration and sampling strategies for observations of winds for use in global circulation models. Simulated data sets have been provided to GSFC, FSU and several LAWS team members. Particular emphasis has been on providing realistic cloud cover, cirrus backscatter, aerosol distribution and wind variance on scales less than 600 km. Progress is currently being made to incorporate other remote sensors (AIRS/AMSU, STIKSCAT) into the global OSSEs

Use of Rearing Cover by Mearns Cottontail

Intensive research on the Mearns cottontail was conducted from March 26 to September 18, 1954, on an 80-acre tract of the Floyd Fleming farm in Decatur County, Iowa. The cover on the 80 acres was alfalfa for hay 13 acres, alfalfa in pasture 21 acres, grass in pasture 8 acres, corn 22 acres, fallow grassland 11 acres, and trees, shrubs and vines along fencelines and gullies and in a catalpa planting about 5 acres. The plants of the fallow grassland, fencelines and gullies were listed by Hubbard and Hendrickson (1952) in some detail

Pheasant Nesting and Production in Winnebago County, Iowa, 1940 versus 1954

The Iowa Cooperative Wildlife Research Unit has conducted research on the ring-necked pheasant (Phasianus colchicus) since 1935 on the Winnebago Research Area. From 1939-41 intensive nesting studies were made (Baskett, 1947) and again from 1950- 54. However, during this latter period, other investigations curtailed a complete nesting investigation, and it was not until 1954 (Klonglan, 1955) that time was available for a complete study with comparable spring pheasant populations. Since fall pheasant population levels in the 1939-41 period were estimated at 140 to 400 birds per section as compared to 100 to 110 birds from 1950-54, an intensive nesting study was deemed advisable for comparative purposes

Community Based Study of the Influence of Social class on the Prevalence and Clinical Profile of Adolescent Facial Acne Vulgaris

Background: Facial acne vulgaris is the most common disease of the skin in adolescents. In Nigeria, studies of the prevalence of  dolescent facial acne vulgaris, lesion type and distribution, and influence of social class on prevalence are few. The aim of this study was to determine the prevalence of adolescent facial acne vulgaris, clinical characteristics, and the influence of social class on this prevalence. Methods: This was a community‑based cross‑sectional study. One thousand and seventy‑nine students from four secondary schools (two private and two public) were assessed. Students were clinically examined for facial acne vulgaris, and acne severity was graded. A structured questionnaire for sociodemographic variables was administered to the students. Data were analyzed using SPSS 16. Results: One thousand and seventy‑nine students were studied; 52% were male, and 47.9% were female. The students were aged 9–20 years with a mean age of 14 ± 2.1 years. The prevalence of facial acne vulgaris was found to be 53.2%. More females (56.7%) had acne than males (50%), the prevalence was found to increase from 28% in the 9–11 years age group to 71.1% in the 18–20 years age group and more prevalent in adolescents from the high social class (60.7%). The severity of acne was mild in 67.2%, moderate in 28.9%, and severe in 4.9%. Conclusion: Prevalence of adolescent facial acne vulgaris increases with age, more prevalent in adolescents from a high social class. Male gender, age, a family history of acne, and previous treatment of acne contribute to the severity of acne. Keywords: Acne vulgaris, adolescent, clinical profile, prevalence, severity, social class&nbsp

Epidemiology and clinical profile of vitiligo in Ibadan, Nigeria

Background: Vitiligo patients are seen routinely in the Dermatology Outpatient Clinic of the University College Hospital Ibadan, Nigeria. However, the epidemiologic and clinical profile of these patients is not documented. The aim of this study was to document the clinical (age of onset, location, severity, class of vitiligo) and sociodemographic characteristics of these patients.Methods: This is a retrospective descriptive study of patients treated for vitiligo from January 2005 to December 2009 at the University College Hospital (UCH) Ibadan dermatology outpatient clinic. Patient records were retrieved and a study proforma was used to assess patient’s information. Data was analyzed using SPSS version 16.Results: Over the study period, 130 vitiligo patients seen but only 111 case notes were retrieved. The mean age at onset in children was 7.8±4.0 and 34.6±17.1 in adults, M:F was 1:1. The commonest type of vitiligo was acrofacial, area of onset was the face/scalp in 59.2%, re-pigmentation was reported in 66%, active lesions in 59.7%, severity of vitiligo was <9% in 90%, Vitiligo was in visible (exposed) parts of the body 84.7% and asymptomatic in 92.7%.Conclusions: The clinical profile of vitiligo in Ibadan, Nigeria is similar to that observed in other places with only females having a genital onset and acrofacial vitiligo being the dominant type seen. Also, treatment modality varies between children and adults

The Cancer Scholarship Program: An Iowan Tradition

Many highly able and motivated students in science have interest in research. Student participation in the total science process, including data collection, recording, reporting, experimental interpretation, synthesis and even publication, can provide the ultimate means of activating science potential. A cooperative effort between the American Cancer Society (ACS) - Iowa Division and The University of Iowa has provided this type of experience, as a facet of the Research Participation Program. For the past 12 years, 100 students who have completed grade 10, 11, or 12, representing 50 Iowa communities, have received financial support from the ACS to participate in the Cancer Scholarship Program (CSP). For six or eight weeks during the summer months, these students have researched in diversified disciplines including biochemistry, internal medicine, microbiology, nutrition sciences, otolaryngology, pharmacology, radiology, surgery and zoology. Many of the research studies have been interdisciplinary in nature, often on the cutting edge of new discoveries

Method and apparatus for disabling an echo canceller on a digital telecommunications network

A method and apparatus for disabling an echo canceller in a framed digital network from a remote terminal that is copuled to the network through an unframed data link. Control is effected by sending N different bit sequences from the remote terminal, where N is the number of different framing alignments that may be imposed on the unframed data by the network. The different sequences are chosen so that one will be framed by the network as the requisite control tone regardless of which framing alignment is actually imposed