On the propagation of a normal shock wave through a layer of incompressible porous material

A novel numerical formulation of the two-phase macroscopic balance equations governing the flow field in incompressible porous media is presented. The numerical model makes use of the Weighted Average Flux (WAF) method and Total Variation Diminishing (TVD) flux limiting techniques, and results in a second-order accurate scheme. A shock tube study was carried out to examine the interaction of a normal shock wave with a thin layer of porous, incompressible cellular ceramic foam. Particular attention was paid to the transmitted and reflected flow fields. The numerical model was used to simulate the experimental test cases, and their results compared with a view to validating the numerical model. A phenomenological model is proposed to explain the behaviour of the transmitted flow field

LAGOVirtual: A Collaborative Environment for the Large Aperture GRB Observatory

We present the LAGOVirtual Project: an ongoing project to develop platform to collaborate in the Large Aperture GRB Observatory (LAGO). This continental-wide observatory is devised to detect high energy (around 100 GeV) component of Gamma Ray Bursts, by using the single particle technique in arrays of Water Cherenkov Detectors (WCD) at high mountain sites (Chacaltaya, Bolivia, 5300 m a.s.l., Pico Espejo, Venezuela, 4750 m a.s.l., Sierra Negra, Mexico, 4650 m a.s.l). This platform will allow LAGO collaboration to share data, and computer resources through its different sites. This environment has the possibility to generate synthetic data by simulating the showers through AIRES application and to store/preserve distributed data files collected by the WCD at the LAGO sites. The present article concerns the implementation of a prototype of LAGO-DR adapting DSpace, with a hierarchical structure (i.e. country, institution, followed by collections that contain the metadata and data files), for the captured/simulated data. This structure was generated by using the community, sub-community, collection, item model; available at the DSpace software. Each member institution-country of the project has the appropriate permissions on the system to publish information (descriptive metadata and associated data files). The platform can also associate multiple files to each item of data (data from the instruments, graphics, postprocessed-data, etc.).Comment: Second EELA-2 Conference Choroni, Venezuela, November 25th to 27th 200

" Could you open this jar for me please": a pilot study of the physical nature of jar opening.

The Department of Trade and Industry have recently published a report highlighting the problems of opening foodstuff packaging. The aim of this pilot study was to observe and document the different techniques used by a range of male and female subjects as they tried to open one of the packaging types highlighted in the report as difficult to open, a vacuum-sealed fruit jam jar. Three types of fruit jam jars were assessed with four subjects, two males and two females. Each subject was physically characterised. During the task performance upper limb posture and the forces applied through the jam jar were recorded using a video camera, a CODA motion capture system and a universal grip dynamometer (UGD). The relationship between the physical characteristics and task performance will be discussed in relation to vacuum jar packaging design, and the appropriateness of the assessment methods used

Dynamic Kerr Effect and Spectral Weight Transfer in the Manganites

We perform pump-probe Kerr spectroscopy in the colossally magnetoresistive manganite Pr0.67Ca0.33MnO3. Kerr effects uncover surface magnetic dynamics undetected by established methods based on reflectivity and optical spectral weight transfer. Our findings indicate the connection between spin and charge dynamics in the manganites may be weaker than previously thought. Additionally, important differences between this system and conventional ferromagnetic metals manifest as long-lived, magneto-optical coupling transients, which may be generic to all manganites.Comment: 12 text pages, 4 figure

The tail of the Jurassic fish Leedsichthys problematicus (Osteichthyes: Actinopterygii) collected by Alfred Nicholson Leeds - an example of the importance of historical records in palaeontology

The specimen of the tail of <i>Leedsichthys problematicus</i>, now in The Natural History Museum, London, was one of the most spectacular fossil vertebrates from the Oxford Clay Formation of Peterborough, but as an isolated find it shares no bones in common with the holotype of the genus and species. However, a letter from Alfred Nicholson Leeds and related documents cast valuable new light on the excavation of the tail, indicating that it was discovered with cranial bones, gill-rakers, and two pectoral fins, thereby including elements that can potentially be compared with those of the holotype. The documents also clearly indicate that The Natural History Museum's specimen is not part of the same individual as any other numbered specimen of <i>Leedsichthys</i> as had been speculated on other occasions. The maximum size of the animal represented by The Natural History Museum's specimen was possibly around 9 metres, considerably less than previous estimates of up to 27.6 metres for <i>Leedsichthys</i>. Historical documentary evidence should therefore be rigorously checked both when studying historical specimens in science, and in preparing text for museum display labels

Milk production and lamb growth in Ojinegra sheep breed

El presente trabajo pretende caracterizar la capacidad productiva de las ovejas de la raza Ojinegra a dos niveles de condición corporal (CC; BAJA, ≤ 2.50 vs. ALTA, > 2.50) y evaluar el crecimiento de sus corderos para la producción de corderos del tipo lechal (10-12 kg de peso vivo a 45 días de edad máxima). Para el ensayo se utilizaron 58 ovejas Ojinegras de Teruel con parto en invierno. La ración provista fue de 1 kg de pienso al día y paja de cereal a voluntad. Se registró el peso vivo peso (PV) de ovejas y corderos semanalmente durante las seis semanas de lactación, y la CC de las ovejas en el parto, a mitad de lactación (3ª semana) y al destete (6ª semana). De estas ovejas se eligió al azar un grupo de 22 ovejas para llevar a cabo el estudio de la producción de leche y concentraciones de metabolitos en sangre relacionados con el balance energético (ácidos grasos no esterificados, AGNE, y β-hidroxibutirato, BHB). Los resultados mostraron que el PV de la oveja Ojinegra (49,0 ± 1,5 kg) se vio afectado por la semana de lactación (P 0,05). Los contenidos de AGNE y BHB en sangre durante la lactación no se vieron afectados por la CC al parto (p > 0,05), mostrando valores medios de AGNE y BHB de 0,30 ± 0,06 y 0,54 ± 0,02 mmol/l, respectivamente. Sin embargo, los AGNE sí decrecieron significativamente a medida que avanzaba la lactación (P 0,05), obteniéndose una producción media de leche de 813 g/día (producción estándar de 702 ml/día). La ganancia media diaria (GMD) de los corderos durante la lactación fue independiente de la CC de la oveja al parto (148 vs. 154 ± 9 g/día, en ALTA vs. BAJA, P > 0,05). El peso medio de los corderos en el momento del destete fue de 9,6 ± 0,3 kg. De este trabajo se puede concluir que la producción de leche de las ovejas de raza Ojinegra de Teruel es moderada, permitiendo un crecimiento limitado de los corderos que puede condicionar el cumplimiento de la edad máxima para alcanzar el peso de la categoría lechal (45 días hasta 10-12 kg). Estos resultados deberían ser contrastados con futuros estudios que evalúen la capacidad lechera y maternal de dicha oveja con distintos sistemas de manejo y alimentación.The aim of this study was to characterize the productive potential of the Ojinegra sheep breed at two levels of body condition score (BAJA, ≤ 2.50 vs. ALTA, > 2.50), so that to prospect the production of suckling lambs (10-12 kg live weight at a threshold of 45 days old). Fifty-eight winter-lambing Ojinegra ewes were used. Ewes were stalled indoors and fed 1 kg of concentrate per day and cereal straw ad libitum. Live weight (PV) of ewes and lambs were registered weekly during lactation (6 weeks). Body condition score (CC) of ewes was measured at lambing and at weeks 3 and 6 of lactation. Twenty-two ewes were randomly selected to evaluate milk production and blood metabolites related with energy balance (nonesterified fatty acids, AGNE, and β-hydroxybutyrate, BHB). Ewes’ PV after lambing was affected by the week of lactation (P 0.05). Blood AGNE and BHB contents were not affected by CC at lambing (P > 0.05), with mean values of 0.30 ± 0.06 and 0.54 ± 0.02 mmol/l for AGNE and BHB respectively. However, AGNE concentration decreased during lactation (P < 0.001). Week of lactation and CC at lambing had no effect on milk production (P > 0.05); with mean milk production of 813 g/day (mean standardized production 702 ml/day). The average daily gain (ADG) of lambs was not affected by ewes’ CC at lambing (148 vs. 154 ± 9 g/day, for ALTA vs. BAJA, respectively; P > 0.05). The average PV of lambs at weaning was 9.6 ± 0.3 kg. In conclusion, milk production of Ojinegra sheep breed is moderate and it might condition the attainment of target 10-12 kg live-weight for suckling lamb category at a maximum age of 45 days old. These results should be confirmed in future studies, assessing the maternal capacity of Ojinegra ewe under diverse management and feeding systems

Concentrations of mephedrone in cases of fatal and non-fatal clinical intoxications

Peer reviewe

Institutional Repository saber.ula.ve: A testimonial perspective

In this paper, we describe our decade-long experience of building and operating one of the most active Institutional Repository in the world: www.saber.ula.ve (University of the Andes, Merida-Venezuela). In order to share our experience with other institutions, we firstly explain the steps we followed to preserve and disseminate the scientific production of the University of Los Andes' researchers. We then present some recent quantitative results about our repository activities and we outline some methodological guidelines that could be applied in order to replicate similar experiences. These guidelines list the ingredients or building blocks as well as the processes followed for developing and maintaining the services of an Institutional Repository. These include technological infrastructure; institutional policies on preservation, publication and dissemination of knowledge; recommendations on incentives for open access publication; the process of selection, testing and adaptation of technological tools; the planning and organization of services, and the dissemination and support within the scientific community that will eventually lead to the adoption of the ideas that lie behind the open access movement. We summarize the results obtained regarding the acceptance, adoption and use of the technological tools used for the publication of our institution's intellectual production, and we present the main obstacles encountered on the way.Comment: 7th International Conference on Open Access in Accra Ghana from 2nd to 3rd November 200

Insights into the role of major bioactive dietary nutrients in lamb meat quality: a review

Feed supplementation with α-linolenic acid (ALA) and linoleic acid (LA) increases their content in muscle, ALA increases n-3 polyunsaturated fatty acids and decrease n-6/n-3 ratio in muscle, and LA increases rumenic acid. However, high LA supplementation may have negative effects on lambs’ lipid oxidative stability of meat. When the sources of ALA and LA are fed as fresh forage, the negative effects are counterbalanced by the presence of other bioactive compounds, as vitamin E (mainly α-tocopherol) and polyphenols, which delay the lipid oxidation in meat. There is a wide consensus on the capability of vitamin E delaying lipid oxidation on lamb meat, and its feed content should be adjusted to the length of supplementation. A high dietary inclusion of proanthocyanidins, phenolic compounds and terpenes reduce the lipid oxidation in muscle and may improve the shelf life of meat, probably as a result of a combined effect with dietary vitamin E. However, the recommended dietary inclusion levels depend on the polyphenol type and concentration and antioxidant capacity of the feedstuffs, which cannot be compared easily because no routine analytical grading methods are yet available. Unless phenolic compounds content in dietary ingredients/supplements for lambs are reported, no specific association with animal physiology responses may be established.This review was funded by Ministry of Science, Innovation and Universities of Spain (Grant numbers: INIA RTA2017–00008-C02–01 and − 02), and the Technology Transfer Operation of the Rural Development Program of Catalonia 2014–2020 (Government of Catalonia and the European Regional Development Funds, Grant code 01.02.01)