Practical application of the geometric geoid for heighting over Nairobi county and its environs

Geoid determination is one of the main current geodetic problems in Kenya. This is because a geoid model is required to convert ellipsoidal heights to orthometric heights that are used in practice. A local geometric geoid covering Nairobi County and its environs has been determined by a geometric approach. Nineteen points levelled by both Global Positioning System (GPS) and precise levelling techniques in the area of study have been used. Seven triangulation points have been used for the determination of transformation parameters between World Geodetic System 1984 (WGS84) and Arc‐Datum 1960 coordinates in order to express the local geoid height as a function of position. The geoid height is expressed as a function of the local plane coordinates through a biquadratic surface polynomial, using 14 GPS/levelling points. Five points have been used for testing the results. The experience with Nairobi County and its environs geometric geoid indicates that interpolation of geoid heights in a small area by a biquadratic polynomial is simple and it works well. The geoid heights obtained by biquadratic polynomial (interpolation) compare favourably on the test points with root mean square and standard deviation of ±1cm in the area of study. This accuracy is sufficient for most engineering projects.Key words: Geoid, GPS, coordinate transformation, height determination, Nairobi Count

Business opportunities analysis using GIS: the retail distribution sector

[EN] The retail distribution sector is facing a difficult time as the current landscape is characterized by ever-increasing competition. In these conditions, the search for an appropriate location strategy has the potential to become a differentiating and competitive factor. Although, in theory, an increasing level of importance is placed on geography because of its key role in understanding the success of a business, this is not the case in practice. For this reason, the process outlined in this paper has been specifically developed to detect new business locations. The methodology consists of a range of analyzes with Geographical Information Systems (GISs) from a marketing point of view. This new approach is called geomarketing. First, geodemand and geocompetition are located on two separate digital maps using spatial and non-spatial databases. Second, a third map is obtained by matching this information with the demand not dealt with properly by the current commercial offer. Third, the Kernel density allows users to visualize results, thus facilitating decision-making by managers, regardless of their professional background. The advantage of this methodology is the capacity of GIS to handle large amounts of information, both spatial and non-spatial. A practical application is performed in Murcia (Spain) with 100 supermarkets and data at a city block level, which is the highest possible level of detail. This detection process can be used in any commercial distribution company, so it can be generalized and considered a global solution for retailers.Roig Tierno, H.; Baviera-Puig, A.; Buitrago Vera, JM. (2013). Business opportunities analysis using GIS: the retail distribution sector. Global Business Perspectives. 1(3):226-238. doi:10.1007/s40196-013-0015-6S22623813Alarcón, S. (2011). The trade credit in the Spanish agrofood industry. Mediterranean Journal of Economics, Agriculture and Environment (New Medit), 10(2), 51–57.Alcaide, J. 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Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe

Global variation in anastomosis and end colostomy formation following left-sided colorectal resection

Background End colostomy rates following colorectal resection vary across institutions in high-income settings, being influenced by patient, disease, surgeon and system factors. This study aimed to assess global variation in end colostomy rates after left-sided colorectal resection. Methods This study comprised an analysis of GlobalSurg-1 and -2 international, prospective, observational cohort studies (2014, 2016), including consecutive adult patients undergoing elective or emergency left-sided colorectal resection within discrete 2-week windows. Countries were grouped into high-, middle- and low-income tertiles according to the United Nations Human Development Index (HDI). Factors associated with colostomy formation versus primary anastomosis were explored using a multilevel, multivariable logistic regression model. Results In total, 1635 patients from 242 hospitals in 57 countries undergoing left-sided colorectal resection were included: 113 (6·9 per cent) from low-HDI, 254 (15·5 per cent) from middle-HDI and 1268 (77·6 per cent) from high-HDI countries. There was a higher proportion of patients with perforated disease (57·5, 40·9 and 35·4 per cent; P < 0·001) and subsequent use of end colostomy (52·2, 24·8 and 18·9 per cent; P < 0·001) in low- compared with middle- and high-HDI settings. The association with colostomy use in low-HDI settings persisted (odds ratio (OR) 3·20, 95 per cent c.i. 1·35 to 7·57; P = 0·008) after risk adjustment for malignant disease (OR 2·34, 1·65 to 3·32; P < 0·001), emergency surgery (OR 4·08, 2·73 to 6·10; P < 0·001), time to operation at least 48 h (OR 1·99, 1·28 to 3·09; P = 0·002) and disease perforation (OR 4·00, 2·81 to 5·69; P < 0·001). Conclusion Global differences existed in the proportion of patients receiving end stomas after left-sided colorectal resection based on income, which went beyond case mix alone

Community-level epidemiology of soil-transmitted helminths in the context of school-based deworming: Baseline results of a cluster randomised trial on the coast of Kenya

Most epidemiological studies of soil-transmitted helminth (STH) infections focus on school-going children. The majority of large-scale cross-sectional and longitudinal community-based studies have been conducted prior to the implementation of wide-scale mass drug administration (MDA). This study investigates age-related patterns in prevalence and intensity of STH infection, and associated risk factors, in a region of south coastal Kenya that had previously received three consecutive years of school-based deworming (2012–14) and four rounds of community-based MDA for lymphatic filariasis between 2003 and 2014. Between March and May 2015, a cross-sectional survey was conducted in 120 community clusters as a baseline for a cluster randomised trial. Individuals aged two years and above were randomly selected during household surveys and requested to provide stool samples, which were assessed for presence and intensity of STH using the duplicate Kato-Katz thick smear method. Species-specific predictors of presence and intensity were investigated through multilevel logistic regression and zero-inflated negative binomial regression models. Of the 19,684 individuals who provided a stool sample, 21.5% were infected with at least one STH. Hookworm was the predominant species, with an overall prevalence of 19.1%; Trichuris trichiura prevalence was 3.6% and Ascaris lumbricoides was negligible (0.4% prevalence). The vast majority were light intensity infections. Prevalence and intensity of hookworm infection were significantly higher in adults and males, and were associated with environmental conditions, low socio-economic status, household flooring, individual and household water, sanitation and hygiene (WASH) characteristics and behaviours, previous treatment, lack of shoe-wearing and not attending school. In contrast, T. trichiura was more commonly found in school-aged boys and those living in communities close to the coast, with reduced infection in the least poor individuals with private latrine access. Overall, results show that despite several years of school-based deworming, hookworm infection remains common among untreated adults in this population, suggesting that this strategy alone is insufficient to reduce community-wide hookworm infection and in the longer term to eliminate transmission