Repairable Block Failure Resilient Codes

In large scale distributed storage systems (DSS) deployed in cloud computing, correlated failures resulting in simultaneous failure (or, unavailability) of blocks of nodes are common. In such scenarios, the stored data or a content of a failed node can only be reconstructed from the available live nodes belonging to available blocks. To analyze the resilience of the system against such block failures, this work introduces the framework of Block Failure Resilient (BFR) codes, wherein the data (e.g., file in DSS) can be decoded by reading out from a same number of codeword symbols (nodes) from each available blocks of the underlying codeword. Further, repairable BFR codes are introduced, wherein any codeword symbol in a failed block can be repaired by contacting to remaining blocks in the system. Motivated from regenerating codes, file size bounds for repairable BFR codes are derived, trade-off between per node storage and repair bandwidth is analyzed, and BFR-MSR and BFR-MBR points are derived. Explicit codes achieving these two operating points for a wide set of parameters are constructed by utilizing combinatorial designs, wherein the codewords of the underlying outer codes are distributed to BFR codeword symbols according to projective planes

Modelling methodology of MEMS structures based on Cosserat theory

Modelling MEMS involves a variety of software tools that deal with the analysis of complex geometrical structures and the assessment of various interactions among different energy domains and components. Moreover, the MEMS market is growing very fast, but surprisingly, there is a paucity of modelling and simulation methodology for precise performance verification of MEMS products in the nonlinear regime. For that reason, an efficient and rapid modelling approach is proposed that meets the linear and nonlinear dynamic behaviour of MEMS systems.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838

Getting more than a fair share: nutrition of worker larvae related to social parasitism in the Cape honey bee Apis mellifera capensis

Besides activation of ovaries and thelytokous reproduction of Cape workers, larval nutrition is an important aspect in parasitism of the African honey bee. When reared by workers of other subspecies, Cape larvae receive more food which is slightly more royal jelly-like. This results in worker-queen intermediates, with reduced pollen combs, enlarged spermathecae and higher numbers of ovarioles. The intermediates weigh more and develop faster than normal workers. The appearance of worker-queen intermediates probably affects parasitism of the African honey bee colonies by Cape workers. Different levels of larval nutrition resulting in less distinct caste differentiation may be important for the reproductive success of Cape workers in their own colonies. Similar processes, albeit less pronounced, may occur in colonies of other subspecies

Effectiveness of blood transfusions and risk factors for mortality in children aged from 1 month to 4 years at the Bon Marche Hospital, Bunia, Democratic Republic of Congo

Objective  To assess the effectiveness of blood transfusions in a hospital of north-eastern Democratic Republic of the Congo. Methods  Prospective study of children admitted for severe anaemia. During admission, data were collected on clinical condition and haemoglobin levels, before and after blood transfusion. A linear regression model was built to explore factors associated with haemoglobin level after transfusion. Risk factors for mortality were explored through multivariate logistic regression. Results  Haemoglobin level (Hb) was below 4 g/dl in 35% (230/657), between 4 and 6 g/dl in 58% (348/657) and at least 6 g/dl in another 6% (43/657) of the transfused children. A transfusion of 15 ml/kg of whole blood increased the Hb from 4.4 to 7.8 g/dl. Haemoglobin level after transfusion was associated with baseline Hb, quantity of delivered blood and history of previous transfusions. Overall case-fatality rate was 5.6% (37/657). Risk factors for deaths were co-morbidities such as chest infection, meningitis or malnutrition, Hb ≥ 6 g/dl, impaired consciousness or jugular venous distention on admission, and provenance. Conclusion  Transfusion was a frequent practice, the use of which could clearly have been rationalised. While indications should be restricted, quantities of transfused blood should be adapted to needs

The effect of pre-service science teachers’ prior experiences on their interests about chemistry experiments

AbstractThe aim of the study was to examine the learners’ interests about chemistry experiments based on their previous science experiences. Sample of the study consisted of 52 first year pre-service science teachers. The data gathered through chemistry experiments which preferred by the learners and an open ended survey. Results showed that participants prepared a chemistry experiment which they found easy to implement and understandable. It was also concluded that the experiments that have been chosen by most of the students have not been tried before for reasons such as lack of equipment or teachers not demonstrating experiments at the school

Met gezonde bijen naar de heide

Op 22 maart 2010 kwam een bont gezelschap van bijenhouders van ABTB, ANI en NBV bijeen in Hoenderloo. Het onderwerp die avond was de vraag: “Hoe combineer ik varroabestrijding met de heidedracht?” Hieronder het antwoord en wel in de vorm van de basisprincipes van varroa bestrijding plus een concrete methode om deze te combineren met de heidedracht