13 research outputs found
Rheological characterization of linear low-density polyethylene-Fischer-Tropsch wax blends
No full textDATA AVAILABILITY STATEMENT :
The data that support the findings of this study are available
from the corresponding author, Shatish Ramjee,
upon request.Please read abstract in the article.Sasol.http://wileyonlinelibrary.com/journal/vnlam2024Chemical EngineeringSDG-09: Industry, innovation and infrastructur
Erratum
No full textIn the letter entitled 'Vaginal insertion and douching practices among sex workers at truck stops in KwaZuluNatal', which appeared on p. 470 of the April 1998 SAMJ, the name of the second author, Gita Ramjee, was inadvertently omitted. We apologise to Or Ramjee and her co-authors for this unfortunate error.
Geographical Clustering of High Risk Sexual Behaviors in “Hot-Spots” for HIV and Sexually Transmitted Infections in Kwazulu-Natal, South Africa
No full textWe investigated geographical variations of three sexually transmitted infections (STIs) namely chlamydia, gonorrhea and syphilis in the greater Durban area, so as to optimize intervention strategies. The study population was a cohort of sexually active women who consented to be screened in one of three biomedical studies conducted in Durban. A total of nine local regions collectively formed three clusters at screening, five of which were previously defined as HIV hot-spots. STI cases were geo-coded at the census level based on residence at the time of screening. Spatial SaTScan Statistics software was employed to identify the areas with a disproportionate prevalence and incidence of STI infection when compared to the neighboring areas under study. Both prevalence and incidence of STIs were collectively clustered in several localized areas, and the majority of these locations overlapped with high HIV clusters and shared the same characteristics: younger age, not married/cohabitating and multiple sex partners. © 2013 The Author(s)
HIV transmission risk through anal intercourse: systematic review, meta-analysis and implications for HIV prevention.
No full textBACKGROUND: The human immunodeficiency virus (HIV) infectiousness of anal intercourse (AI) has not been systematically reviewed, despite its role driving HIV epidemics among men who have sex with men (MSM) and its potential contribution to heterosexual spread. We assessed the per-act and per-partner HIV transmission risk from AI exposure for heterosexuals and MSM and its implications for HIV prevention. METHODS: Systematic review and meta-analysis of the literature on HIV-1 infectiousness through AI was conducted. PubMed was searched to September 2008. A binomial model explored the individual risk of HIV infection with and without highly active antiretroviral therapy (HAART). RESULTS: A total of 62,643 titles were searched; four publications reporting per-act and 12 reporting per-partner transmission estimates were included. Overall, random effects model summary estimates were 1.4% [95% confidence interval (CI) 0.2-2.5)] and 40.4% (95% CI 6.0-74.9) for per-act and per-partner unprotected receptive AI (URAI), respectively. There was no significant difference between per-act risks of URAI for heterosexuals and MSM. Per-partner unprotected insertive AI (UIAI) and combined URAI-UIAI risk were 21.7% (95% CI 0.2-43.3) and 39.9% (95% CI 22.5-57.4), respectively, with no available per-act estimates. Per-partner combined URAI-UIAI summary estimates, which adjusted for additional exposures other than AI with a 'main' partner [7.9% (95% CI 1.2-14.5)], were lower than crude (unadjusted) estimates [48.1% (95% CI 35.3-60.8)]. Our modelling demonstrated that it would require unreasonably low numbers of AI HIV exposures per partnership to reconcile the summary per-act and per-partner estimates, suggesting considerable variability in AI infectiousness between and within partnerships over time. AI may substantially increase HIV transmission risk even if the infected partner is receiving HAART; however, predictions are highly sensitive to infectiousness assumptions based on viral load. CONCLUSIONS: Unprotected AI is a high-risk practice for HIV transmission, probably with substantial variation in infectiousness. The significant heterogeneity between infectiousness estimates means that pooled AI HIV transmission probabilities should be used with caution. Recent reported rises in AI among heterosexuals suggest a greater understanding of the role AI plays in heterosexual sex lives may be increasingly important for HIV prevention
Synthesis and coordination of a neutral phosphaguanidine and comparison of its basicity with a guanidine
No full textA phosphaguanidine [Me2NC(PPh2)=NiPr], the analogous guanidine [Me2NC(NPh2)=NiPr], and their hydrochloride (HCl) salts were prepared to study the influence of substituting a phosphorus atom for a nitrogen atom on the basicity of the two compounds and the bonding in their conjugate acids. The pKa values of both HCl salts were measured in acetonitrile by NMR titration. Surprisingly, the substitution of P for N has essentially no effect on basicity even though the geometry at that atom is changed. The presence of phenyl substituents in the protonated guanidine reduces the resonance in the CN3 core, whereas poor orbital overlap between P and C reduces the resonance in the N2CP core of the protonated phosphaguanidine. The neutral phosphaguanidine binds to a Cu(I) halide through both the Nimine and the P, which suggested that the basic N atom on the bound ligand may have little utility as a Brønsted base. Fortunately, however, a Cu(I) halide complex of the protonated phosphaguanidine is stable. Thus, the tendency of the basic N to bind to metals does not proscribe it serving as a metal-proximate Brønsted base.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
Thermal and rheological properties of Fischer-Tropsch wax/high-flow LLDPE blends
No full textDATA AVAILABILITY STATEMENT :
The data that support the findings of this study are available from the corresponding author upon reasonable request.Waxes find use as processing aids in filled compounds and polyethylene-based masterbatches. In such applications, the thermal and physical property changes they impart to the polymer matrix are important. Therefore, this study details results obtained for blends prepared by mixing a Fischer–Tropsch (F–T) wax with a high-flow linear low-density polyethylene (LLDPE). The melting and crystallization behavior are studied using hot-stage polarized optical microscopy (POM) and differential scanning calorimetry (DSC). The calorimetry results are consistent with partial cocrystallization of the two components. The melting and crystallization exo- and endotherms for the wax- and LLDPE-rich phases remained separate. However, they change in shape and shift toward higher- and lower temperature ranges, respectively. It is found that increasing the wax content delays the crystallization, decreases the overall crystallinity, and reduces the size of the crystallites of the polyethylene-rich phase. Rotational viscosity is measured at 170 °C in the Newtonian shear-rate range. The variation of the zero-shear viscosity with blend composition is consistent with the assumption of a homogeneous melt in which the chains are in an entangled state. Therefore, it is concluded that the wax and LLDPE are, in effect, miscible in the melt and partially compatible in the solid state.Ministerio de Ciencia e Innovación and Sasol.http://www.mame-journal.de/hj2024Chemical EngineeringSDG-09: Industry, innovation and infrastructureSDG-12:Responsible consumption and productio
Evaluating the neutralizing antibody response to HIV-1 membrane proximal external regional; Implications for vaccine design
No full textIncludes bibliographical references.Inducing broadly neutralizing antibodies targeting the HIV-1 envelope is thought to be crucial for developing an effective vaccine. The Membrane Proximal External Region (MPER) within the HIV- 1 gp41 envelope is a promising vaccine target. The MPER is highly conserved, functionally constrained, facilitates virus fusion and is targeted by broadly neutralizing monoclonal antibodies. The objectives of this research were 1) To evaluate the neutralization breadth of antibodies induced by epitopes within the MPER compared to the PG9/16-site in chronically HIV-1-infected individuals, 2) to identify neutralization resistant HIV-1 isolates (using plasma samples infected with the same subtype) and to characterize their sensitivity to anti-MPER antibodies and 3) to determine the accessibility of the MPER to HIV-1 induced polyclonal anti-MPER antibodies in a highly neutralization resistant virus (253-11; CRF02_AG subtype)
Continuous metadata flows for distributed multimedia
No full textThe practical use of temporal multimedia has increased markedly in recent years as enabling technologies for the distribution and streaming of media have become available. As a part of this trend, hypermedia systems and models have adapted accordingly to incorporate such distributed multimedia for presentation. Structured interpretation of information has long been a fundamental feature of both open hypermedia systems and knowledge systems. Metadata, in its many forms, has become the cornerstone for providing this structured knowledge above and beyond basic data and information. This thesis presents the rationale and requirements for continuous metadata, which supports the metadata accompanying distributed multimedia throughout the lifecycle of streamed media, from generation, through distribution, to presentation. Throughout this process it is the temporal and continuous nature of the metadata which is paramount. A conceptual framework for continuous metadata is proposed to encapsulate these principles and ideas. Continuous metadata and the associated framework enable the development, in particular, of real-time, collaborative, semantically enriched distributed multimedia applications. Experience building one such system using continuous metadata is evaluated within the framework. An ontology is developed for the system to enable the collation, distribution, and presentation of structure aiding navigation of multimedia, and it is shown how continuous metadata utilising the ontology can be distributed using multicas
A meta-analytic review of multisensory imagery identifies the neural correlates of modality-specific and modality-general imagery
No full textThe relationship between imagery and mental representations induced through perception has been the subject of philosophical discussion since antiquity and of vigorous scientific debate in the last century. The relatively recent advent of functional neuroimaging has allowed neuroscientists to look for brain-based evidence for or against the argument that perceptual processes underlie mental imagery. Recent investigations of imagery in many new domains and the parallel development of new meta-analytic techniques now afford us a clearer picture of the relationship between the neural processes underlying imagery and perception, and indeed between imagery and other cognitive processes. This meta-analysis surveyed 65 studies investigating modality-specific imagery in auditory, tactile, motor, gustatory, olfactory, and three visual sub-domains: form, color and motion. Activation likelihood estimate (ALE) analyses of activation foci reported within- and across sensorimotor modalities were conducted. The results indicate that modality-specific imagery activations generally overlap with—but are not confined to—corresponding somatosensory processing and motor execution areas, and suggest that there is a core network of brain regions recruited during imagery, regardless of task. These findings have important implications for investigations of imagery and theories of cognitive processes, such as perceptually-based representational systems
Outcomes 30 days after ICU admission: The 30DOS study
No full textBackground: The spectrum of illness and long-term outcome of critically ill patients admitted to intensive care units (ICUs) in South Africa remains largely unknown. Objectives: This study was designed to provide data on ICU outcomes and disease burden in public sector ICUs in KwaZulu- Natal. The primary objective was to describe 30-day mortality of all patients admitted to participating sites. Secondary objectives included clinical demographics and spectrum of illness amongst these patients, and testing a template to demonstrate feasibility of such data collection. Methods: 30DOS was a multicentre, prospective, observational cohort study conducted over 30 days. An a priori decision was made to report study results separately for adults and paediatric patients. This article reports the results for adult patients. The complete 30-DOS study included 11 ICUs in six hospitals. All adult patients admitted to study ICUs were included. Patients were followed up telephonically by a research assistant. Data on patient demographics, preadmission functional scoring, injury severity scoring, co-morbidities, admission diagnosis/es, organ support, and outcome were collected. Results: A total of 228 adults were included. The majority of admissions (73.7%) occurred on an emergency basis, with 68.4% occurring in the postoperative period. Approximately half were for non-communicable disease (49.6%), followed by trauma (29.0%) and infectious disease (21.5%). There were a total of 59 (25.9%) deaths within the first 30 days after admission. In-ICU mortality was 19.7%. There were 12 (5.3%) in-hospital deaths following discharge and two (0.9%) out-of-hospital deaths. Thirtyday survival was known for 174 (76.3%) admissions with a 33.9% mortality rate. Conclusion: Overall in-ICU mortality was 19.7% with a large trauma burden in a young population. Thirty-day mortality was 33.9%. Information pertaining to patient demographics and spectrum of illness provided novel information to further the understanding of the demand placed on critical care resources within South Africa
