1,397 research outputs found
The General Primordial Cosmic Perturbation
We consider the most general primordial cosmological perturbation in a
universe filled with photons, baryons, neutrinos, and a hypothetical cold dark
matter (CDM) component within the framework of linearized perturbation theory.
We give a careful discussion of the different allowed modes, distinguishing
modes which are regular at early times, singular at early times, or pure gauge.
As well as the familiar growing and decaying adiabatic modes and the baryonic
and CDM isocurvature modes we identify two {\it neutrino isocurvature} modes
which do not seem to have been discussed before. In the first, the ratio of
neutrinos to photons varies spatially but the net density perturbation
vanishes. In the second the photon-baryon plasma and the neutrino fluid have a
spatially varying relative bulk velocity, balanced so that the net momentum
density vanishes. Possible mechanisms which could generate the two neutrino
isocurvature modes are discussed. If one allows the most general regular
primordial perturbation, all quadratic correlators of observables such as the
microwave background anisotropy and matter perturbations are completely
determined by a real, symmetric matrix-valued function of
co-moving wavenumber. In a companion paper we examine prospects for detecting
or constraining the amplitudes of the most general allowed regular
perturbations using present and future CMB data.Comment: 18 pages, 2 Postscript figures, uses revtex. Revised 2-2000 Minor
errors corrected and some references adde
Constraining Isocurvature Perturbations with CMB Polarization
The role of cosmic microwave background (CMB) polarisation data in
constraining the presence of primordial isocurvature modes is examined. While
the MAP satellite mission will be unable to simultaneously constrain
isocurvature modes and cosmological parameters, the PLANCK mission will be able
to set strong limits on the presence of isocurvature modes if it makes a
precise measurement of the CMB polarisation sky. We find that if we allow for
the possible presence of isocurvature modes, the recently obtained BOOMERANG
measurement of the curvature of the universe fails. However, a comparably
sensitive polarisation measurement on the same angular scales will permit a
determination of the curvature of the universe without the prior assumption of
adiabaticity.Comment: 4pages, Latex with four eps figures. (Revised 18 Dec 2000. Minor
typos corrected
When does a major outbreak become a Public Health Emergency of International Concern?
The process of determining whether a Public Health Emergencies of International Concern (PHEIC) exists and should be declared has drawn increasing criticism over the past few years with allegations that it is more political than technical. Delaying declaration, where appropriate, means that the opportunity of garnering international solidarity and necessary resources in the early phases of epidemics, when public health measures may be more effective, is lost. A reform agenda aimed at enhancing WHO/Emergency Committee transparency and objectivity for the PHEIC declaration process is required
Rising rates of Caesarean sections: an audit of Caesarean sections in a specialist private practice
Background: Caesarean section (CS) rates are increasing worldwide; rates in the private sector in South Africa are reported to be particularly high.To the best of our knowledge there has been no recent audit of Caesarean sections performed by the private health sector in KwaZulu-Natal. The aimof this study was to carry out an audit of CS in a private practice.Methods: An audit of the patient records over a period of one year was done. No personal identifiers were noted or reported on. All relevant clinicaldata were pooled and used to analyse the clinical information.Results: There were 364 deliveries in the study period and 209 of these were CS, giving a rate of 60.4%. Most of the caesarean sections were carriedout because of a previous CS; maternal request and HIV status also contributed to the high rate.Conclusion: The high CS rate in private practice is probably a window to the increased rates of Caesarean section being performed worldwide.This high rate is in keeping with trends in countries such as South America, and is considerably higher than the ideal rate of 10 to 15% in low-riskobstetric populations suggested by the WHO
Human papillomavirus (HPV) vaccination of adolescents in the South African private health sector: Lessons from the HPV demonstration project in KwaZulu-Natal
In South Africa (SA), >4 000 women die annually of cervical cancer, a disease caused by the human papillomavirus (HPV). Infections caused by certain genotypes of HPV increase the risk of cervical cancer. HIV-infected women in particular are more likely to have persistent HPV infection, with higher-risk genotypes. In SA, two vaccines (HPV quadrivalent (types 6, 11, 16, and 18) vaccine, recombinant (Gardasil) and HPV bivalent (types 16 and 18) vaccine, recombinant (Cervarix)) are currently registered for the prevention of HPV-related disease. In the past, there have been significant challenges to achieving high coverage and uptake of vaccination – contributory factors include cost and lack of awareness. An HPV demonstration project among schoolgirls in rural KwaZulu-Natal showed that high vaccine uptake is achievable. In 2014, the National Department of Health launched the national HPV vaccination programme among female learners attending public schools. Awareness of HPV vaccination among healthcare providers, education of parents, teachers and learners, and avoidance of missed opportunities for vaccination are vital to the success of the programme. Primary healthcare practitioners may play an important role in cervical cancer prevention by identifying and offering vaccination to girls who miss the opportunity to be vaccinated at school. HPV vaccination should be considered as one arm of a comprehensive programme of cervical cancer prevention and control
The costs of delivering human papillomavirus vaccination to Grade 4 learners in KwaZulu-Natal, South Africa
Background. The national human papillomavirus (HPV) vaccination roll-out in South Africa provides two doses of Cervarix to all female Grade 4 learners in state schools. This study estimated the costs of vaccinating all learners in KwaZulu-Natal Province (females or males and females) using either the two- or three-dose strategies for both the bivalent and quadrivalent vaccines.Objective. To determine costs of the HPV vaccination programme in KwaZulu Natal.Methods. Costs were determined adapting World Health Organization vaccination costing guidelines.Results. The 2014 current cost of delivering three doses of Gardasil was ZAR510 per learner. The projected cost of delivering Cervarix to female learners at two or three doses over the period 2014 - 2018, adjusted for inflation, was ZAR172 717 342 and ZAR250 048 426, respectively. Similarly, the cost for Gardasil at these doses was ZAR197 482 200 and ZAR287 194 361, respectively. For male and female learners the cost for Cervarix over this period at two or three doses was ZAR337 101 132 and ZAR540 150 713, respectively. Similarly, the cost for Gardasil at these doses was ZAR426 597 971 and ZAR620 392 784, respectively. Accounting for population variation for females over 5 years, the cost of two doses of Cervarix ranged from ZAR168 888 677 to ZAR 176 545 977 at the lower and upper 95% confidence intervals (CIs), respectively. For three doses the cost ranged from ZAR244 505 544 to ZAR255 591 263 at the lower and upper 95% CIs, respectively. Similarly, the cost for two doses of Gardasil ranged from ZAR193 104 566 to ZAR201 859 798. For three doses the cost ranged from ZAR280 828 057 to ZAR293 560 614.Conclusion. This study gives decision makers a basis for structured planning and cost apportionment to ensure effective roll-out of the HPV vaccination programme
Medicinal plants with cholinesterase inhibitory activity: A Review
Alzheimer’s disease (AD), a common neurodegenerative disease, is characterized by low levels in the brain of the neurotransmitter, acetylcholine (ACh). Clinical treatment of this disease is palliative and relies mostly on enhancing cholinergic function by stimulation of cholinergic receptors or prolonging the availability of ACh released into the neuronal synaptic cleft by use of agents which restore or improve the levels of acetylcholine. Inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), enzymes which breakdown acetylcholine, are considered as a promising strategy for the treatment of AD. A potential source of AChE and BChE inhibitors is provided by the abundance of plants in nature, and natural products continue to provide useful drugs and templates for the development of other compounds. The present work constitutes a review of the literature on 123 species of medicinal plants that have been tested for AChE inhibitory activity and 42 plant species which have been tested for BChE inhibitory activity. The plant species listed are potential cholinesterase inhibitors and may aid researchers in their study of natural products which may be useful in the treatment of AD.Key words: Alzheimer’s disease, acetylcholine, acetylcholinesterase, butyrylcholinesterase and medicinal plants
Massive pulmonary haemorrhage as a cause of death in the neonate - a retrospective review
Objectives. To examine massive pulmonary haemorrhage as an independent factor and as a co-factor in neonatal mortality by analysing the associated factors, with the purpose of identifying predisposing characteristics.Design. A retrospective study reviewing 32 neonates who died of pulmonary haemorrhage. Data were extracted from the 2001 King Edward VIII Hospital (KEH) neonatal death records. Relevant obstetric and neonatal variables were used in the data analysis.Setting. KEH, a tertiary care institute, provides secondary and tertiary services and functions as a referral centre for surrounding clinics and hospitals.Results. Pulmonary haemorrhage occurred in 32 of 260 neonatal fatalities (12.3%). All cases of pulmonary haemorrhage fell into the low-birth-weight category ( < 2 500 g), and 26 of the infants (81.25%) died during theearly neonatal period. A gestational age of 28 - 32 weeks was recorded in 27 cases (87%) and 19 (60%) showed adequate growth for gestational age. Three infants had pulmonary haemorrhage as a primary cause of death. In the remaining 29, pulmonary haemorrhage was secondary to a variety of causes. Obstetric information revealed that 29 mothers (93.5%) experienced obstetric complications, viz. preeclampsia/ eclampsia syndrome 21 (64.5%), abruptio placentae 5 (16.1 %) and previous pregnancy losses 9 (29%). Seven babies were ventilated and 2 were diagnosed with patent ductus arteriosus.Conclusion. The study revealed more well-grown babies than expected. Complications of pregnancy hypertension, abruptio placentae and previous pregnancy losses were more frequently associated with pulmonary haemorrhage in these neonates. The majority of babies suffering pulmonary haemorrhage were not associated with intensive care management
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