17,739 research outputs found
What we can learn from magnetic Compton scattering : application to the determination of spin polarization
Studies of spin-resolved electron momentum densities involve the measurement of the so-called magnetic Compton profile. This is a one-dimensional projection of the electron momentum distribution of only those electrons that contribute to the spin moment of a sample. The technique is applicable to ferri- and ferromagnetic materials. The profile is obtained via the inelastic 'Compton' scattering of high energy X-rays. Since electrons originating from different atomic orbitals have specific momentum densities, it is often possible to determine the origin of the magnetism present. Typically, interpretation requires the use of electronic structure calculations using molecular orbital and band structure approaches. Here, we highlight the application of the technique to the determination of the Fermi level spin polarization, the knowledge of which is important to the development of novel spintronic materials
Imaging African trypanosomes
Trypanosoma brucei are extracellular kinetoplastid parasites transmitted by the blood-sucking tsetse fly. They are responsible for the fatal disease human African trypanosomiasis (HAT), also known as sleeping sickness. In late-stage infection, trypanosomes cross the blood–brain barrier (BBB) and invade the central nervous system (CNS) invariably leading to coma and death if untreated. There is no available vaccine and current late-stage HAT chemotherapy consists of either melarsoprol, which is highly toxic causing up to 8% of deaths, or nifurtimox–eflornithine combination therapy (NECT), which is costly and difficult to administer. There is therefore an urgent need to identify new late-stage HAT drug candidates. Here, we review how current imaging tools, ranging from fluorescent confocal microscopy of live immobilized cells in culture to whole-animal imaging, are providing insight into T. brucei biology, parasite-host interplay, trypanosome CNS invasion and disease progression. We also consider how imaging tools can be used for candidate drug screening purposes that could lead to new chemotherapies
Breast cancer in young women: prevalence of LOH at p53, BRCA1 and BRCA2
Breast cancer in young women: prevalance of LOH at p53, BRCA1 and BRCA
Exact properties of Frobenius numbers and fraction of the symmetric semigroups in the weak limit for n=3
We generalize and prove a hypothesis by V. Arnold on the parity of Frobenius
number. For the case of symmetric semigroups with three generators of Frobenius
numbers we found an exact formula, which in a sense is the sum of two
Sylvester's formulaes. We prove that the fraction of the symmetric semigroups
is vanishing in the weak limit
Communities` attitudes towards conservation in Gashakagumti National Park Nigeria
This study assessed the attitudes of communities around GashakaGumti National Park towards conservation. It also investigated factors that influence these conservation attitudes. Data were obtained through structured questionnaire which covered demographic characteristics, perceived benefits and challenges derived from the park and responses to attitudinal statements. Data were subjected to descriptive and inferential analysis. The result indicated that 79.3% of the respondents had a positive attitude towards conservation on GashakaGumti National Park. Perceived benefits derived from the Park included construction of classrooms, roads, medical centre, employment opportunity, improved economy through tourist inflow while perceived challenges included destruction of farm produce by wild animals and lack of access to fodder for livestock. 78.9% of the respondents were willing to be involved in community based projects planning and execution. 94.7% accepted and supported community development projects. 100% supported the continued existence of the park. The positive conservation attitude of the respondents might be attributed to the perceived economic benefits derived from the park and the communities` willingness to be involved in community based projects. Result of the chi square and correlation analysis indicated gender, occupation, level of education, perceived benefits and distance from the park had significant relationship with attitude towards conservation in GashakaGumti National Park. The authorities of the park should not relent in their effort in maintaining their peaceful co existence with the surrounding communities but ensure consolidation of this feat. The park management should look into the issues considered as challenges by communities to avert conflict, animosity and breeding of negative conservation attitudes. It is also recommended that attitudinal studies should be conducted periodically and incorporated into National Park Service Management Plan.Key words: Attitudes, Conservation, Benefits, GashakaGumti National Par
Challenges with using estimates when calculating ART need among adults in South Africa
Background. The Foundation for Professional Development (FPD) collects information annually on HIV/AIDS service provision and estimates service needs in the City of Tshwane Metropolitan Municipality (CTMM).Methods. Antiretroviral therapy (ART) data from the Department of Health and Statistics South Africa (SSA) mid-year population estimates were used to approximate the ART need among adults in the CTMM.Results. According to SSA data, ART need decreased dramatically from 2010 to 2011 and was lower than the number of adults receiving ART. Although the noted difference was probably due to changes in the calculations by SSA, no detailed or confirmed explanation could be offered.Conclusions. We provide a constructive contribution to the discussion regarding the use of model-derived estimates of ART need
Prostate Cancer Screening, Detection and Treatment Practices, Among Sub-Saharan African Urologists
Introduction: Prostate cancer is reported to be the leading cancer in men in Sub-Saharan Africa (SSA) and the number of prostate cancer deaths is expected to double in the next 20 years. Despite the importance of this public health issue in SSA, there remains relatively limited information about practices related to prostate cancer treatment in this population. Objective: We conducted a survey of 28 urology practices in SSA to evaluate the scope of available screening, detection and treatment. Materials and Methods: Screening was more commonly reported as a part of general medical care in South Africa (SA) compared with East or West (EW) Africa. However, use of digital Rectal Examination (DRE) and Prostate Specific Antigen (PSA) were used at similar rates for screening in all locations. Screening is primarily focused in men over age 50 and those with symptoms. Routine screening was the primary reason for screening use in SA, while symptoms were the primary reason for screening use in EW. Financial and cultural barriers to screening were more commonly reported in EW than SA. Similar detection approaches were used in all regions, with free PSA and PSA velocity being more commonly used in SA than EW. Six core biopsies were more commonly used in EW and 12 core biopsies were more common in SA. Trans urethral ultrasounds and bone scans were more commonly used in SA than EW. Treatment options were similar in all regions, with brachytherapy less likely to be used in EW than SA. Results: The descriptive data suggest that differences in patterns of screening, detection and treatment exist across Africa. Differences by geography may also reflect differences in SES and racial composition of the populations in each region.Key Words: Prostate cancer, Screening and Detection, Practice guidelines, Sub-Saharan Afric
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