Background: The HIV epidemic is a serious public health concern globally. There are 1,692,242 million known non-citizens in South Africa; this is equivalent to 3.3% of the total South African population (Statistics South Africa [STATS SA], 2011) this reflects global trends relating to number of non-citizens living in foreign countries (Vearey, 2008). Migration is an important demographic process to consider when studying HIV transmission as it increases migrants’ susceptibility to HIV (International Organisation for Migration [IOM], 2010). International migration, which is the movement of people across international borders, can result in migrants finding themselves in spaces of vulnerability which may lead to risky sexual behaviour (IOM, 2010). Furthermore, access to healthcare may be limited due to the dynamics of living in a foreign country. Internal migration, defined as the movement of people within the borders of a country (IOM, 2010) may result in ‘intra-urban’ inequalities that inhibit access to basic services such as housing and healthcare (Nunez et al, 2011). Despite it being the smallest province in the country, Gauteng has the highest level of in-migration, with an estimated net inflow of 367 100 internal migrants as for the period 2006–2011 (STATS SA, 2011). Globally, international migrants are more seriously considered as a concern for HIV transmission. However, in South Africa, internal migrants are equally as concerning particularly due to their circular migratory patterns. Knowledge of one’s status is a crucial first step in management of HIV. Voluntary HIV testing remains a challenging aspect of public health interventions, especially amongst key populations such as migrants (WHO, 2010). Although numerous studies have been conducted around migration and HIV, there remained a need for an investigation into the factors that influence HIV testing among Johannesburg residents. This is particularly significant, given the rapidly increasing levels of migration into the city, as well as the high urban HIV prevalence, which has been found to be twice high as that in rural areas and highest within urban informal settlements (Vearey, 2010). Therefore, this study set out to examine factors associated with HIV testing among residents of Johannesburg, in an attempt to determine whether migration status matters or not. Methods: This is a quantitative study with a sample size of 487 Johannesburg residents. International (n=150) and internal migrants (n=293) were examined in relation to each other and a comparative group of Johannesburg natives (n=44). STATA version 11 was utilised to conduct secondary data analysis of the RENEWAL survey (2008). This data, which was collected using a cross-sectional study design, was acquired from the African Centre for Migration and Society (ACMS) at the University of the Witwatersrand. Univariate descriptive analysis, bivariate chi-squared test and multivariate, logistic regression models were employed. Results: Levels of HIV testing were found to be higher amongst internal migrants (56%) when compared to international migrants (42%), (x2(1) =0.62; Pr=0.004). There was only a slight difference between Johannesburg natives and internal migrants who reported a 55% chance of HIV testing (x2(2) =8.32; Pr=0.016).These findings were only significant at the bivariate level. Overall, factors that were significantly associated with HIV testing amongst residents are: sex (95% CI 2.01 to 4.88; p=0.000); type of residence (95% CI 0.29 to 0.76; p=0.003); knows where to locate a testing facility (95% CI 1.41 to 3.50; p=0.001) and knows that anti-retroviral treatment (ART) is free (95% CI 1.93 to 4.83; p=0.000). Income was significantly associated with HIV testing amongst migrants (95% CI 0.40 to 0.90, p=0.016). Females were three times more likely (3.14) to test for HIV when compared to males. The odds of getting an HIV test by those who resided in informal settlements were less (0.48) when comparing with those who stay in formal housing. Residents who knew where to locate a HIV testing facility were twice (2.22) as likely to get tested for HIV as compared to those who did not know where to find one. Residents who knew that ART is free were three times as likely (3.05) to get tested for HIV as compared to those who did not. Those who were not earning a salary were less likely (0.61) to get tested for HIV compared to those who were earning a salary. Conclusion: The fact that migrant status, that is -internal versus international migration as a variable is not significant against HIV testing at the multivariate level indicates that there are far more important mediating factors that determine HIV testing than migration. More importantly, a more detailed and focused exploration into the length of stay of migrants in the city as well as the effect of urban inequalities on health, is needed.

Schnellläuferstrategien sind Lagerstrategien, welche den Durchsatz von Lagern durch geeignete Wahl der Lagerorte im Lager steigern. Die verschiedenen existierenden Strategien wurden bisher uneinheitlich beschrieben und umgesetzt. Aussagen zu Durchsatzsteigerungen fallen schwer. Die existierenden Strategien werden systematisiert und als Vergleichsbasis für die neue Strategie "Dynamische Zonierung" herangezogen. Die "Dynamische Zonierung" ist dabei sowohl die einfachste als auch die leistungsfähigste Schnellläuferstrategie. Dafür sorgt die konsequente Anwendung zweier Verfahren, welche bereits einzeln sinnvoll sind, aber erst gemeinsam ihr volles Potential entfalten: Erstens erübrigt die Abbildung der Verweildauerverteilung auf die Fahrzeitverteilung jegliche Zonierung. Damit entfallen die Aufwände für Planung und Berechnung von Zonengrenzen und -zuordnungen. Gleichzeitig kann so die bei Zonenbildung unvermeidliche Abbildungsunschärfe beseitigt werden. Eine von einer optimalen Zuordnung abweichende Lagerortwahl resultiert nun ausschließlich aus Prognosefehlern. Zweites stellt die lagereinheitsbasierte Verweildauerbetrachtung die korrekte Umsetzung des als optimal nachgewiesenen Cube-Per-Order-Kriteriums dar. Ohne Zwang zur Zonenbildung fehlen die der Verwendung lagereinheitsbasierter Verweildauern sonst entgegenstehenden algorithmischen Mehraufwände. Dass auch die Prognose lagereinheitsbasierter Verweildauern für Teile des Sortimentes nicht zu Mehraufwand sondern zur Vereinfachung des Verfahrens führt, spricht zusätzlich für die lagereinheitsbasierte Betrachtung. Auch bei herkömmlicher artikelorientierter Betrachtungsweise kann die Dynamische Zonierung dadurch Leistungsvorteile herausarbeiten. / Turnover-based storage strategies are strategies in warehousing which increase the system throughput by choosing favorable storage locations. Existing strategies have been described and implemented inconsistently when compared to each other. Statements on strategy gains are difficult. Therefore a categorization of turnover-based strategies is devised. The existing strategies serve as basis of comparison for the new strategy "Dynamic Zoning". "Dynamic Zoning" proves to be the simplest turnover-based strategy while giving the highest performance at the same time. This is accomplished by combining two methods. These methods are reasonable when used separately, but only reach their full potential when used together. First, mapping the dwell time (duration of stay) probability distribution to the travel time probability distribution lets zones become obsolete. Efforts to plan and calculate zones can be avoided and the inevitable imprecision when mapping to zones vanishes. Any deviation from the optimal storage location now results from errors in estimation. Second, dwell times must be based on unit loads which is the correct application of the cube-per-order-criterion for optimality. Without the need to use zones this does not result in extra effort to apply the strategy. For a part of the assortment the estimation of unit load dwell times is simpler than before too, making unit load dwell times even more appealing. However, even when using conventional article based dwell time estimates the strategy "Dynamic Zoning" results in higher performance than other strategies.

Schnellläuferstrategien sind Lagerstrategien, welche den Durchsatz von Lagern durch geeignete Wahl der Lagerorte im Lager steigern. Die verschiedenen existierenden Strategien wurden bisher uneinheitlich beschrieben und umgesetzt. Aussagen zu Durchsatzsteigerungen fallen schwer. Die existierenden Strategien werden systematisiert und als Vergleichsbasis für die neue Strategie "Dynamische Zonierung" herangezogen. Die "Dynamische Zonierung" ist dabei sowohl die einfachste als auch die leistungsfähigste Schnellläuferstrategie. Dafür sorgt die konsequente Anwendung zweier Verfahren, welche bereits einzeln sinnvoll sind, aber erst gemeinsam ihr volles Potential entfalten: Erstens erübrigt die Abbildung der Verweildauerverteilung auf die Fahrzeitverteilung jegliche Zonierung. Damit entfallen die Aufwände für Planung und Berechnung von Zonengrenzen und -zuordnungen. Gleichzeitig kann so die bei Zonenbildung unvermeidliche Abbildungsunschärfe beseitigt werden. Eine von einer optimalen Zuordnung abweichende Lagerortwahl resultiert nun ausschließlich aus Prognosefehlern. Zweites stellt die lagereinheitsbasierte Verweildauerbetrachtung die korrekte Umsetzung des als optimal nachgewiesenen Cube-Per-Order-Kriteriums dar. Ohne Zwang zur Zonenbildung fehlen die der Verwendung lagereinheitsbasierter Verweildauern sonst entgegenstehenden algorithmischen Mehraufwände. Dass auch die Prognose lagereinheitsbasierter Verweildauern für Teile des Sortimentes nicht zu Mehraufwand sondern zur Vereinfachung des Verfahrens führt, spricht zusätzlich für die lagereinheitsbasierte Betrachtung. Auch bei herkömmlicher artikelorientierter Betrachtungsweise kann die Dynamische Zonierung dadurch Leistungsvorteile herausarbeiten. / Turnover-based storage strategies are strategies in warehousing which increase the system throughput by choosing favorable storage locations. Existing strategies have been described and implemented inconsistently when compared to each other. Statements on strategy gains are difficult. Therefore a categorization of turnover-based strategies is devised. The existing strategies serve as basis of comparison for the new strategy "Dynamic Zoning". "Dynamic Zoning" proves to be the simplest turnover-based strategy while giving the highest performance at the same time. This is accomplished by combining two methods. These methods are reasonable when used separately, but only reach their full potential when used together. First, mapping the dwell time (duration of stay) probability distribution to the travel time probability distribution lets zones become obsolete. Efforts to plan and calculate zones can be avoided and the inevitable imprecision when mapping to zones vanishes. Any deviation from the optimal storage location now results from errors in estimation. Second, dwell times must be based on unit loads which is the correct application of the cube-per-order-criterion for optimality. Without the need to use zones this does not result in extra effort to apply the strategy. For a part of the assortment the estimation of unit load dwell times is simpler than before too, making unit load dwell times even more appealing. However, even when using conventional article based dwell time estimates the strategy "Dynamic Zoning" results in higher performance than other strategies.

The distribution of the population has multiple implications on regional development and planning. In-migration is frequently seen as the only possible solution in order to rejuvenate the population and stimulate regional development in sparsely populated regions. A population increase results in greater tax revenues, meaning that local authorities can plan for their inhabitants and expenditures in a more sufficient way. In addition, certain professionals are needed in order to support essential local services such as schools and hospitals. Place marketing with the intention of attracting in-movers has become increasingly popular, especially for rural, sparsely populated Swedish municipalities. Still, the outcome from place marketing efforts are dubious and in addition, migration has a temporal aspect and individual migration propensity usually fluctuates over time. This begs the question – how long do in-movers stay? Is there potential for long lasting development in sparsely populated regions connected to in-movers or is it temporary? This study focuses on the duration of time until an in-mover re-migrates from Region 8 in northern Sweden and which socioeconomic and demographic factors that influences the out- migration. This is studied by applying an event history method with discrete-time logistic regressions. The study follows individuals in working age that moved to any of nine specified municipalities in Västerbotten and Norrbotten County, sometime between 2000 and 2011. Questions posed for the study is: i) On average, how long did people who moved to Region 8 between the years 2000-2011 stay in the region? ii) What are the socioeconomic and demographic factors that influence the out-migration from the region? iii) Do the influencing factors differ between women and men? The results show that the time perspective matters as the risk of moving out was highest in the initial years and that it declines with time. 30 % of the sampled in-movers had moved out again within the time of observation, and on average the in-movers stayed for nine years. The regression results indicated that the factors that had the greatest influence on the out- migration was unemployment, being between 20-26 years old, high education, having and unemployed partner, and having children below school age. Women had a slightly lower likelihood of moving out compared to men, and the most prominent influential factor to outmigration that varied between women and men was unemployment.