A statistical analysis of errors associated with the AV-8B sensor suite

The Marine Expeditionary Unit (MEU) battlefield continues to evolve with conflicts around the world, requiring quick, precision strike capability. In support of MEU air operations, the AV-8B Harrier needs air-to-surface munitions which, once released from the aircraft, guide autonomously to the designated target coordinates. Global Positioning System (GPS) directed bomb-on-coordinate (BOC) weapons such as the Joint Direct Attack Munition (JDAM), Joint Stand-Off Weapon (JSOW) and Joint Attack Strike Missile (JASM) fulfill this capability. In-flight targeting of BOC munitions against fixed and re-locatable targets is a derived requirement of the weapon to aircraft integration. This paper is an analysis of the target location error (TLE) associated with target coordinates generated using the following AV-8B aircraft sensors: the AN/APG-65 radar utilizing medium resolution synthetic aperture radar (MRSAR) mapping, the Angle-Rate Bombing System (ARBS) using an electro-optical (EO)-TV designation, and the Head- Up Display (HUD) using visual Global Positioning System - Inertial Navigation System (GPS-INS) designations. The three major TLE contributors associated with each sensor designation are aircraft position error, operator error and sensor error. This analysis validates the use of the AV-8B sensor suite in directing BOC weapons in the following priority: ARBS designations provide for the minimum TLE and should be used as the primary source for direction of BOC weapons such as JDAM. HUD designations provide for a minimization of TLB and should be used as the secondary source for direction of HOC weapons such as JDAM, provided the ARBS or AN/APG-65 radar is used to determine target elevation. MRSAR map designations do not provide for minimization of TLB and should not be used to direct a single BOC weapon against a single target designation. Further study is required to determine if the designations are accurate enough to direct multiple weapons against a single target designation

Knowledge regarding basic concepts of hereditary cancers, and the available genetic counselling and testing services: A survey of general practitioners in Johannesburg, South Africa

Background. In families with hereditary cancer, at-risk individuals can benefit from genetic counselling and testing. General practitioners (GPs) are ideally placed to identify such families and refer them appropriately.Objective. To assess the practices, knowledge and attitudes of GPs regarding common hereditary cancers.Methods. An exploratory research design was used. An existing questionnaire was adapted, piloted and mailed to 196 GPs in Johannesburg, South Africa. The 61 GPs (31.1%) who completed and returned the questionnaire constituted the final sample. Data were analysed using descriptive statistics.Results. The GPs obtained some information on cancer family history from their patients, but not enough to assess the risks. Altogether 22 (36.1%) of the GPs referred patients to appropriate facilities for assessment and testing, while 32 (52.5%) were aware of genetic testing services. Most (38/61, 62.3%) were not familiar with the genetic counselling facilities available, but they felt patients should have counselling before testing. Less than half knew about possible paternal inheritance, or the low rate of hereditary mutations and their penetrance. Overall, the majority of GPs (53/61, 86.9%) were interested in learning more about cancer genetics and available services, and they expected to play an increasing role in the field in the future.Conclusions. Many of the GPs in this study had limited knowledge about inherited cancers, cancer risk management and genetic services. Appropriate education needs to be increased so that they are better equipped to identify and refer families at risk

The role of the genetic counsellor: a systematic review of research evidence

In Europe, genetic counsellors are employed in specialist genetic centres or other specialist units. According to the European Board of Medical Genetics, the genetic counsellor must fulfil a range of roles, including provision of information and facilitation of psychosocial adjustment of the client to their genetic status and situation. To evaluate the extent to which genetic counsellors fulfil their prescribed roles, we conducted a systematic review of the published relevant scientific evidence. We searched five relevant electronic databases (Medline, CINAHL, SocIndex, AMED and PsychInfo) using relevant search terms and handsearched four subject-specific journals for research-based papers published in English between 1 January 2000 and 30 June 2013. Of 419 potential papers identified initially, seven satisfied the inclusion criteria for the review. Themes derived from the thematic analysis of the data were: (i) rationale for genetic counsellors to provide care, (ii) appropriate roles and responsibilities and (iii) the types of conditions included in the genetic counsellor caseload. The findings of this systematic review indicate that where genetic counsellors are utilised in specialist genetic settings, they undertake a significant workload associated with direct patient care and this appears to be acceptable to patients. With the burden on genetic services, there is an argument for the increased use of genetic counsellors in countries where they are under-utilised. In addition, roles undertaken by genetic counsellors in specialist genetic settings could be adapted to integrate genetic counsellors into multi-disciplinary teams in other specialisms

Accuracy of pulse oximetry in pigmented patients

Objective. Prospective assessment of the accuracy of three pulse oximeters and  two probe sites in darkly pigmented critically·i11 patients under clinical conditions.Patients and methods. One hundred consecutive, darkly pigmented critically ill adutt patients with arterial lines in situ were studied. Patients were excluded if thehaemoglobin concentration was less than 7 g/dl and carboxyhaemoglobin or  methaemoglobin levels exceeded 2%. Pigmentation was objectively quantified with a portable EEL reflectance spectrophotometer (Evans E1ectroselenium Company, Diffusion Systems Limited. London). Reflectance was measured at nine wavelengths.Results. The degree of pigmentation as measured by percentage reflectance closely matched that of a control group of black Africans from a pigmentation study. The limits of agreement (2.6% to 5.8%), precision and bias values between pulse  oximeter and co-ox!meter readings fell within a narrow range. The 95% confidence intervals of the limits of agreement reflected a small variation in the difference between pulse oximeter and co-oximeter readings. These small differences were not clinically. significant in the pigmented patients who were enrolled in the study.Conclusion. The accuracy of pulse oximetry is not adversely affected by skin  pigmentation, and it remains a useful oxygenation monitoring device in darkly pigmented patients

Types of albinism in the black Southern Africa population

Background: Oculocutaneous albinism (OCA) is the most common inherited disorder in Southern African blacks and several types have been described. Molecular techniques, where available, can be used to confirm a clinical diagnosis and the type of OCA, if necessary, and for prenatal diagnosis.Objectives: To investigate and classify the different types of albinism commonly found and to determine the clinical implications for each type.Design: A descriptive survey.Setting: Gauteng province, South Africa, and Lesotho.Subjects: Three groups of subjects with OCA (96 from a genetics clinic, 62 from a dermatology clinic, and 31 from community surveys) from the black African population participated.Main outcome measures: Subjects underwent clinical and/or dermatological examinations and were then classified according to type of OCA.Results: Four forms of OCA were identified: most (82%) subjects had OCA2 (a tyrosinasepositive type) with three sub-types: those without large freckles (ephelides) on exposed areas (named OCA 2a in this study), those with such freckles (named OCA 2b), and those with brown albinism (BOCA); the remainder had red/ rufous albinism, ROCA (OCA 3). The four forms could be distinguished from each other clinically without using molecular genetic testing.Conclusion: The most common types of albinism found in the black population of Southern Africa are OCA 2 and OCA 3. Given the high prevalence of the disorder, together with the high risk of skin cancer, and the recent persecution of affected individuals in certain East African countries, these findings and their clinical implications have significance in terms of both education and awareness for health professionals andlay people caring for those with albinism

Epilepsy in rural South African children prevalence, associated disability and management

Objective. To determine the prevalence of epilepsy and its associated disabilities in rural South African children aged 2 - 9 years.Setting. Eight villages in the district of Bushbuckridge, Northern Province, South Africa_Design. A two-phase design was used_ The first phase involved screening children on a house-to-house baSis by interviewing mothers or caregivers using an internationally validated questionnaire for detecting childhood disability in developing countries. The second phase consisted of a paediatric/ neurodevelopmental assessment of the children who screened positive.Results. A total of 6692 children were screened; 722 (10.8%) had a paediatric evaluation and 49 (0.73%) had epilepsy. The· lifetime and active prevalences of epilepsy in these children were 7.3/1 000 and 6.7/1 000 respectively. Associated developmental disability was recorded in 35 affected children (71.4%), including 8 (16.3%) in whom this was moderate to severe. More than a half of the children with epilepsy (57.1%) did not receive anticonvulsant medication.Conclusion. The prevalence of epilepsy in the rural childhood population investigated is higher than that recorded in most similar studies from sub-Saharan Africa, and the poor utilisation of 'appropriate anticonvulsant treatment is cause for concern. This study highlights the paucity of relevant information on the epidemiology of epilepsy in South Africa and that the system available for its management, especially in rural areas, appears to have functional deficiencies. Appropriate research is needed to identify the problems in service delivery and to enable the planning and implementation of an appropriate primary health care-based system for the diagnosis and management of epilepsy in children