Tr-Island - Combating Urban Heat Islands in the City Centre in Hanover

As part of the HeKris research and exchange, this paper presents a creative proposal in dealing with the issue of urban heat islands in the city centre of Hannover. The area in question is essentially fragmented due to heat island effects making some streets and connecting roads unbearable to walk through. By utilising the old tram infrastructure on Prinzenstraße and Schiffgraben, the project unifies the area and creates a more attractive public realm network. The introduction of vegetation and water elements in urban areas was found beneficial to reduce the heat island effect significantly. The paper further emphasises the importance of a comprehensive urban governance-oriented implementation process and recommends the introduction of a resilience-focused action programme to achieving sustainable urban development in and around Hanover

Parametric deconvolution for a common heteroscedastic case

>Magister Scientiae - MScThere exists an extensive statistics literature dealing with non-parametric deconvolution, the estimation of the underlying population probability density when sample values are subject to measurement errors. In parametric deconvolution, on the other hand, the data are known to be from a specific distribution. In this case the parameters of the distribution can be estimated by e.g. maximum likelihood. In realistic cases the measurement errors may be heteroscedastic and there may be unknown parameters associated with the distribution. The specific realistic case is investigated in which the measurement error standard deviation is proportional to the true sample values. In this case it is shown that the method of moment’s estimation is particularly simple. Estimation by maximum likelihood is computationally very expensive, since numerical integration needs to be performed for each data point, for each evaluation of the likelihood function. Method of moment’s estimation sometimes fails to give physically meaningful estimates. The origin of this problem lies in the large sampling variations of the third moment. Possible remedies are considered. Due to the fact that a convolution integral needed to be calculated for each data point, and that this has to be repeated for each iteration towards the solution, maximum likelihood computing cost is very high. New preliminary work suggests that saddle point approximations could sometimes be used for the convolution integrals. This allows much larger datasets to be dealt with. Application of the theory is illustrated with simulation and real data

Spatial and temporal distribution of insect vectors of Xanthomonas campestris pv. musacearum and their activity across banana cultivars grown in Rwanda.

Insect vectors of Xanthomonas campestris pv musacearum (Xcm) have played a major role in long distance and plant to plant transmission of Xanthomonas wilt of banana (XW). The prevalence of insects has been reported to vary in space and time. Some banana cultivars have also been reported to attract more insect vectors of Xcm than others. The present study was conducted to determine the spatial and temporal distribution of insect vectors of Xcm and assess their activity across banana cultivars grown in Rwanda. The study was carried out in four banana growing areas of Rwanda selected on the basis of their altitude (i.e.Low, Medium and High). The Kivu Lake Border region was selected as a fourth site due to the high prevalence of XW. Insects were sampled in the four annual seasons (short dry, short rainy, long dry and long rainy) and at different times of the day. During sampling of insects, the incidence of XW-male bud infection was also recorded. Collected insects were immediately sorted into taxonomic groups and conserved in vials containing 70% ethanol for further identification to genus and species level. Five insect specimens in each taxon were put aside for the isolation of Xcm on their external body parts. There was a high prevalence of fruit flies, honey bees and other flies (in other families than Drosophilidae and Tephritidae) compared with wasps, ants and beetles. More insects were recorded in the low altitude area and during the long rainy season. These findings correlated with the observed high incidence of XW in the wet seasons. Incidence of floral infections was higher in the low altitudes declining with the increase in altitude, correlating with the decline in insect activity as altitude increased. The activity of insects on banana male buds varied among banana cultivars, with more activity on beer (AAA-East African Highland (EAH) and ABB types) and dessert banana cultivars compared with cooking or mixed use cultivars. Among the cooking types only ‘Injagi’ and its clone sets ‘Barabeshya’ and ‘Incakara’ attracted large insect populations. Banana cultivars ‘Nkazikamwe’ (cooking AAA-EAH), ‘Impura’ (beer AAAEAH) and ‘Ikinyangurube’ (dessert AAA) possessed persistent male bracts and neuter flowers and were less attractive to flower visitors. These cultivars could be promoted in areas prone to insect vector infections. Timely and proper de-budding should be emphasized with special attention during the rainy seasons and for banana cultivars with non-persistent male buds

Variation in nectar volume and sugar content in male flowers of Musa cultivars grown in Rwanda and their non-effect on the numbers of visiting key diurnal insect vectors of banana Xanthomonas wilt

Insects are a major mode of banana Xanthomonas wilt (XW) spread. High insect activity has been blamed for the high XW incidence in ‘Kayinja’ (ABB-genome) dominated banana landscapes across east and central Africa. ‘Kayinja’ male bud nectar composition reportedly contributes to high insect activity. The variation in nectar composition with agro-ecological zones and banana cultivars and its influence on the number of visiting insects in Rwanda were assessed. Three male buds were collected per cultivar for nectar extraction and analysis using a high performance liquid chromatography. Nectar volume and sugar concentrations varied (P<0.001) across 27 banana cultivars, annual seasons and agro-ecological zone. The highest nectar volume was recorded among the East African highland cooking cultivars (AAA-genome) in the high altitude site and the short-heavy rainy season. Nectar contained three sugars: glucose, fructose and sucrose, though hexose (glucose and fructose) was dominant. The three sugars varied significantly (P<0.001) within each cultivar. The total nectar-sugar concentration ranged from 2.3–32%, with the highest among dessert cultivars ‘Kamaramasenge’ (AAB-genome) and ‘Gisukari’ (AAA-genome). No strong correlation occurred between insect population and total nectar sugar concentration or nectar volume. Insect populations were rather influenced by the weather conditions, the long rainy season characterized by moderate well distributed rainfall recording the highest insect populations as compared to the short rainy season (with heavy rainfall) and the dry seasons

Phytochemical Screening and in vitro Antimicrobial Activity of Dracaena Afromontana Leaves

Dracaena afromontana is a native species grown in the high mountain rainforest of Rwanda. This plant finds many traditionally medicinal uses in the treatment of chest pain, dermatitis, liver diseases and malaria. In this report, the dried Bay leaves were extracted with n-hexane, ethyl acetate and methanol by maceration giving 0.717 g (1.434%), 1.457 g (2.914%) and 6.319 g (12.64%) respectively. The extracts were concentrated for further phytochemical screening and evaluated for antimicrobial activity against E. coli and S. aureus using well diffusion method. In addition, the dracaena afromontana extracts were analyzed using thin layer chromatographic separation techniques leading to the identification and characterization of bioactive compounds including, terpenoids, flavonoids, tannins, phenols, saponins, reducing sugar and quinones. The results from TLC indicate that the higher retention factor (Rf2 = 0.77) was obtained via the use of ethyl acetate, whereas n-hexane gave a retention factor (Rf3 = 0.558). On the other hand, the methanol extract did not show any separation. The antimicrobial assay for the extracts was carried out using Lurial broth agar and Manitor salt over lay method. The findings of antimicrobial assay showed that methanolic extract of dracaena afromontana leaves has an antibacterial activity against the gram negative bacteria E.coli with the zone of inhibition of 16 mm, while the antibacterial activity of ethyl acetate extract against E. coli showed a smaller inhibition zone of 10 mm for diluted inoculums (10-2 and 10-1). For the gram positive bacteria S. aureus the inhibition zone by Dracaena afromontana was insignificant, whereby the methanolic and ethyl acetate extracts showed a maximum inhibition zone of 4 mm and 3 mm respectively. The n-hexane extract did not show any antibacterial activity against both pathogenic organisms

Musa germplasm diversity status across a wide range of agro-ecological zones in Rwanda

Objectives: This study assessed the on-farm Musa germplasm diversity across different agro-ecologies of Rwanda and the socio-economic utilization options and selection practices that create/maintain this diversity on-farm.Methodology and results: A Musa germplasm diagnostic survey was carried out in 2007 in five Rwandan districts on a transect from Lake Kivu (West) to Kirehe district (East) bordering Tanzania. Across all sites, 118 farms, each having at least 50 mats were sampled for determining Musa diversity. Forty three Musa cultivars were recorded across the five districts. Higher diversity was observed in the east declining westwards to the Lake Kivu region as reflected by the number of cultivars and their relative abundance. Nearly half of the recorded cultivars had a low diversity index (Gini-Simpson 1-D &lt; 0.2) and therefore prone to genetic erosion. Cooking cultivars only dominate in the district of Kirehe, while beer cultivars dominate the banana production landscape in the other districts. Taste/flavor, bunch size and market demand were the most important criteria for banana cultivar selection and thus greatly influenced cultivar conservation and distribution on-farm. Diseases such as Fusarium wilt and Xanthomonas wilt greatly contributed to genetic erosion.Conclusion and application of results: Musa cultivar diversity in Rwanda is under threat. Ex-situ conservation of the menaced cultivars is of crucial importance. Beer cultivars dominated the landscape. Cultivar diversity on-farm was influenced by the prevailing altitude; taste/flavor, bunch size, and market demand of the cultivars; and their susceptibility to diseases especially Fusarium and Xanthomonas wilt. Banana breeding or adaptation strategies therefore should take into account the farmer preferred traits. In addition, strategies for managing these diseases are critical for preventing the genetic erosion of the affected cultivars.Keywords: cultivar evenness, cultivar richness, diversity index, genetic erosio

Musa germplasm diversity status across a wide range of agro-ecological zones in Rwanda

This study assessed the on-farm Musa germplasm diversity across different agro-ecologies of Rwanda and the socio-economic utilization options and selection practices that create/maintain this diversity on-farm. Methodology and results: A Musa germplasm diagnostic survey was carried out in 2007 in five Rwandan districts on a transect from Lake Kivu (West) to Kirehe district (East) bordering Tanzania. Across all sites, 118 farms, each having at least 50 mats were sampled for determining Musa diversity. Forty three Musa cultivars were recorded across the five districts. Higher diversity was observed in the east declining westwards to the Lake Kivu region as reflected by the number of cultivars and their relative abundance. Nearly half of the recorded cultivars had a low diversity index (Gini-Simpson 1-D < 0.2) and therefore prone to genetic erosion. Cooking cultivars only dominate in the district of Kirehe, while beer cultivars dominate the banana production landscape in the other districts. Taste/flavor, bunch size and market demand were the most important criteria for banana cultivar selection and thus greatly influenced cultivar conservation and distribution on-farm. Diseases such as Fusarium wilt and Xanthomonas wilt greatly contributed to genetic erosion. Conclusion and application of results: Musa cultivar diversity in Rwanda is under threat. Ex-situ conservation of the menaced cultivars is of crucial importance. Beer cultivars dominated the landscape. Cultivar diversity on-farm was influenced by the prevailing altitudes; taste/flavor, bunch size, and market demand of the cultivars; and their susceptibility to diseases especially Fusarium and Xanthomonas wilt. Banana breeding or adaptation strategies therefore should take into account the farmer preferred traits. In addition, strategies for managing these diseases are critical in the prevention of the genetic erosion of the affected cultivars

A Novel Epidemic Model for the Interference Spread in the Internet of Things

Due to the multi-technology advancements, internet of things (IoT) applications are in high demand to create smarter environments. Smart objects communicate by exchanging many messages, and this creates interference on receivers. Collection tree algorithms are applied to only reduce the nodes/paths&rsquo; interference but cannot fully handle the interference across the underlying IoT. This paper models and analyzes the interference spread in the IoT setting, where the collection tree routing algorithm is adopted. Node interference is treated as a real-life contamination of a disease, where individuals can migrate across compartments such as susceptible, attacked and replaced. The assumed typical collection tree routing model is the least interference beaconing algorithm (LIBA), and the dynamics of the interference spread is studied. The underlying network&rsquo;s nodes are partitioned into groups of nodes which can affect each other and based on the partition property, the susceptible&ndash;attacked&ndash;replaced (SAR) model is proposed. To analyze the model, the system stability is studied, and the compartmental based trends are experimented in static, stochastic and predictive systems. The results shows that the dynamics of the system are dependent groups and all have points of convergence for static, stochastic and predictive systems

Developing knowledge and tools for climate change mitigation and adaptation with multi­functional urban green infrastructure – kick-off symposium of the multidisciplinary project “Maximizing the carbon sequestration in urban trees (CliMax)”

Das interdisziplinäre Forschungsprojekt CliMax ist eine Kooperation des Julius Kühn-Instituts und der Technischen Universität Braunschweig. Das Projekt erforscht die Grundlagen für effizientere Entscheidungshilfen für Städte und Kommunen, mit deren Hilfe nicht nur der Status Quo des Beitrages des Stadtgrüns zur Kohlenstoffsequestrierung geschätzt, sondern auch die Klimawirksamkeit des Stadtgrüns maximiert werden kann. Die Berücksichtigung der Multifunktionalität des Stadtgrüns bezieht dessen positive Effekte in eine Entscheidungsmatrix mit ein und unterstützt dadurch die Integration des Klimaschutzaspektes bei Pflanz- oder Pflegeentscheidungen. Zum Anlass des Auftaktsymposiums berichten wir hier von den Projektvorhaben.The interdisciplinary research project CliMax is a cooperation between the Julius Kühn-Institute and the Technische Universität Braunschweig. It provides information on the status quo of the contribution of urban green spaces to carbon sequestration and aims for the development of decision-support tools for maximizing the climate effectiveness of urban green. Considering the multifunctionality of urban green spaces, such tools must incorporate many effects of urban green space into a decision matrix and thereby support the integration of the climate mitigation aspects in planting or maintenance decisions. On the occasion of the kick-off meeting, we report here on our plans for the project

Measurements of Surgical Volume in Low- and Middle-Income Countries, a Systematic Review

Background: Surgical volume is a surgical indicator that was described in the Lancet Commission on Global Surgery (LCoGS) and the World Bank World Development Indicators as an important metric for tracking the delivery of surgical care. Objectives: We aimed to characterize the reports on surgical volume (SV) in the existing literature by using a systematic review to assess studies that examine surgical procedures as a ratio of a population (procedures/100,000 population). Methods: The PRISMA guideline was employed in the systematic review of articles that addressed the measurement of SV in low- and middle-income countries (LMICs), with the primary outcome of surgical procedures/100,000 population. Findings: The search result consisted of 6,657 preliminary studies. Following the title and abstract screening, 6,464 articles were excluded, and the remaining 193 were included in the full text review. From the full text review of the 193, only 26 of these articles defined SV as the ratio of number of procedures per population of the catchment/geographical area. The reported SV was a mean of 765, with an SD of 1260 operations per 100,000. The median SV was 180 (min = 0.900, max = 4470). Conclusion: Our findings support the LCoGS assessment of the gap in surgical care. The target for SV is 5000 per 100,000 population, compared to the average of 765 per 100,000 population as found in this review. The challenges for assessing surgical volume gaps are vast, including the nature of written records, which limits SV reports to an absolute number of procedures per year without a reference to the catchment population. For the purpose of tracking SV, we recommend using proxies that account for the capacity of facilities to deliver care regardless of the catchment population