Minimum Density Hyperplanes

Associating distinct groups of objects (clusters) with contiguous regions of high probability density (high-density clusters), is central to many statistical and machine learning approaches to the classification of unlabelled data. We propose a novel hyperplane classifier for clustering and semi-supervised classification which is motivated by this objective. The proposed minimum density hyperplane minimises the integral of the empirical probability density function along it, thereby avoiding intersection with high density clusters. We show that the minimum density and the maximum margin hyperplanes are asymptotically equivalent, thus linking this approach to maximum margin clustering and semi-supervised support vector classifiers. We propose a projection pursuit formulation of the associated optimisation problem which allows us to find minimum density hyperplanes efficiently in practice, and evaluate its performance on a range of benchmark datasets. The proposed approach is found to be very competitive with state of the art methods for clustering and semi-supervised classification

Acute haemolytic anaemia as a complication of thyphoid fever

No Abstrac

Proteinuria as a predictor of complications of pre-eclampsia

Proteinuria is a defining criterion for the diagnosis of pre-eclampsia. The amount of protein lost per day has been thought by some to predict both maternal and fetal outcome. The systematic review of 16 primary papers including over 6700 patients by Thangaratinam and colleagues published this month in BMC Medicine suggests otherwise. This finding may influence our management of pre-eclampsia

Non-closure of peritoneal surfaces at caesarean section - a systematic review

Background. Caesarean section (CS) is a very common surgical procedure  worldwide. Suturing the peritoneal layers at CS may or may not confer  benefit, hence the need to evaluate whether this step should be omitted or not.Objectives. To assess the effects of non-closure as an alternative to  closure of the peritoneum at CS on intraoperative, immediate and later  postoperative, and long-term outcomes.Search strategy. We searched the Cochrane Pregnancy and Childbirth   Group Trials Register (November 2002) and the Cochrane Central   Controlled Trials Register (October 2003).Selection criteria. Randomised controlled trials that compared leaving the visceral and/ or parietal peritoneum unsutured at CS with suturing the peritoneum, in women undergoing elective or emergency CS.Data collection and analysis. Trial quality was assessed and data were extracted by two reviewers.Main results. Nine trials involving 1 811 women were included and  analysed. The methodological quality of the trials was variable. Non-closure of the peritoneum reduced operating time when both layers or one layer was not sutured. For both layers, the operating time was reduced by7.33 minutes (95% confidence interval (CI): -8.43 - -6.24). There was significantly less postoperative fever and reduced postoperative stay in hospital for non-closure of the visceral peritoneum and non-closure of both layers. There were no other statistically significant differences. The tr.end for analgesia requirement and wound infection tended to favour non-closure, while endometritis results were variable. Longterm follow-up in 1 trial showed no significant differences. The power of the latter study to show differences was low.Conclusions. There was improved short-term postoperative outcome if the peritoneum was not closed. Long-term studies following CS are limited, but data from other surgical procedures are reassuring. At present there is noevidence to justify the time taken and cost of peritoneal closure

Inter-pregnancy interval and risk of recurrent pre-eclampsia: systematic review and meta-analysis

Background: Women with a history of pre-eclampsia have a higher risk of developing pre-eclampsia in subsequentpregnancies. However, the role of the inter-pregnancy interval on this association is unclear.Objective: To explore the effect of inter-pregnancy interval on the risk of recurrent pre-eclampsia or eclampia.Search strategy: MEDLINE, EMBASE and LILACS were searched (inception to July 2015).Selection criteria: Cohort studies assessing the risk of recurrent pre-eclampsia in the immediate subsequentpregnancy according to different birth intervals.Data collection and analysis: Two reviewers independently performed screening, data extraction, methodologicaland quality assessment.Meta-analysis of adjusted odds ratios (aOR) with 95 % confidence intervals (CI) was used to measure the associationbetween various interval lengths and recurrent pre-eclampsia or eclampsia.Main results: We identified 1769 articles and finally included four studies with a total of 77,561 women. The meta-analysisof two studies showed that compared to inter-pregnancy intervals of 2?4 years, the aOR for recurrent pre-eclampsia was 1.01 [95 % CI 0.95 to 1.07, I2 0 %] with intervals of less than 2 years and 1.10 [95 % CI 1.02 to 1.19, I2 0 %] with intervals longerthan 4 years.Conclusion: Compared to inter-pregnancy intervals of 2 to 4 years, shorter intervals are not associated with an increasedrisk of recurrent pre-eclampsia but longer intervals appear to increase the risk. The results of this review should beinterpreted with caution as included studies are observational and thus subject to possible confounding factors.Keywords: Recurrence, Pre-eclampsia, Eclampsia, Inter-pregnancy interval, Birth interval, Meta-analysis, Systematic review,Birth spacing, Hypertensive disorders of pregnancyFil: Cormick, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Epidemiología y Salud Pública. Instituto de Efectividad Clínica y Sanitaria. Centro de Investigaciones en Epidemiología y Salud Pública; ArgentinaFil: Betran, Ana Pilar. World Health Organization; SuizaFil: Ciapponi, Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Epidemiología y Salud Pública. Instituto de Efectividad Clínica y Sanitaria. Centro de Investigaciones en Epidemiología y Salud Pública; ArgentinaFil: Hall, David R.. Stellenbosch University; Sudáfrica. Tygerberg Hospital; SudáfricaFil: Hofmyer, G. Justus. University of the Witwatersrand; Sudáfrica. University of Fort Hare; Sudáfrica. Walter Sisulu University; Sudáfric

Acute high-altitude illness

A substantial proportion of South Africa (SA)’s population lives at high altitude (>1 500 m), and many travel to very high altitudes (>3 500 m) for tourism, business, recreation or religious pilgrimages every year. Despite this, knowledge of acute altitude illnesses is poor among SA doctors. At altitude, the decreasing ambient pressure proportionally decreases available oxygen (hypobaric hypoxia). This triggers both immediate respiratory compensation and gradual acclimatisation that occurs over days to weeks. Rapid ascents to altitudes above 2 500 m can precipitate acute altitude illness, including acute mountain sickness (AMS) and high-altitude pulmonary and cerebral oedema (HAPE and HACE). The best preventive measure is gradual ascent (no more than 300 - 500 m increase in sleeping altitude per day, with additional rest days for acclimatisation for every 1 000 m altitude gain), although chemoprophylaxis may speed acclimatisation. In the field, AMS, HAPE and HACE are diagnosed clinically. The Lake Louise Score questionnaire is used to elicit symptoms of AMS, and can be supplemented by assessing clinical signs such as tachycardia, tachypnoea, crepitations or ronchi, and ataxia. The mainstay of treatment for all but mild AMS is rapid descent to lower altitudes, which can be facilitated by administration of oxygen and drugs, including acetazolamide, dexamethasone and nifedipine, or use of a portable hyperbaric chamber

Expedition medicine: A southern African perspective

A growing number of people are undertaking expeditions and adventure travel to previously inaccessible areas. The risks posed by increasing accessibility of remote regions and interest in extreme sports have not been fully obviated by modern equipment and communications. Therefore, there remains a requirement for medical care during wilderness expeditions, for which expectations and formal standards continue to increase. Expedition medicine should take cognisance of the predicted problems, plan for contingencies, and be practised pragmatically in austere settings. Southern African medics have a broad skill set, which makes them ideally suited to the field, but they should seek to understand the epidemiology of expeditions in different environments, undergo specialised training, and become involved in all phases of planning and execution of an expedition. Routine general practice complaints and accidental trauma are ubiquitous; travel medical issues such as blisters, diarrhoea, insomnia, sunburn and dehydration occur commonly; area/activity-specific issues such as  infectious disease risks and altitude illnesses must be addressed; and women’s health and dental problems are frequently overlooked. The expedition medic plays a wide range of roles, and should have knowledge and skills to match the requirements of the expedition. Fortunately, many resources exist to assist medics in becoming competent in the field

Comparison of System Call Representations for Intrusion Detection

Over the years, artificial neural networks have been applied successfully in many areas including IT security. Yet, neural networks can only process continuous input data. This is particularly challenging for security-related non-continuous data like system calls. This work focuses on four different options to preprocess sequences of system calls so that they can be processed by neural networks. These input options are based on one-hot encoding and learning word2vec or GloVe representations of system calls. As an additional option, we analyze if the mapping of system calls to their respective kernel modules is an adequate generalization step for (a) replacing system calls or (b) enhancing system call data with additional information regarding their context. However, when performing such preprocessing steps it is important to ensure that no relevant information is lost during the process. The overall objective of system call based intrusion detection is to categorize sequences of system calls as benign or malicious behavior. Therefore, this scenario is used to evaluate the different input options as a classification task. The results show, that each of the four different methods is a valid option when preprocessing input data, but the use of kernel modules only is not recommended because too much information is being lost during the mapping process.Comment: 12 pages, 1 figure, submitted to CISIS 201