7,770 research outputs found
Update on field use of the available drugs for the chemotherapy of human African trypanosomiasis
Despite the fact that eflornithine was considered as the safer drug to treat human African trypanosomiasis (HAT) and has been freely available since 2001, the difficulties in logistics and cost burden associated with this drug meant that the toxic melarsoprol remained the drug of choice. The World Health Organization responded to the situation by designing a medical kit containing all the materials needed to use eflornithine, and by implementing a training and drugs distribution programme which has allowed a transition to this much safer treatment. The introduction of the combination of nifurtimox and eflornithine (NECT) has accelerated the shift from melarsoprol to the best treatment available, due to reduced dosage and treatment time for eflornithine that has significantly lessened the cost and improved the burden of logistics encountered during treatment and distribution. The decrease in the use of more dangerous but cheaper melarsoprol has meant a rise in the per patient cost of treating HAT. Although NECT is cheaper than eflornithine monotherapy, an unexpected consequence has been a continuing rise in the per patient cost of treating HAT. The ethical decision of shifting to the best available treatment imposes a financial burden on HAT control programmes that might render long-term application unsustainable. These factors call for continuing research to provide new safer and more effective drugs that are simple to administer and cheaper when compared to current drug
An assessment of the educational potential of a fisheries management simulation game for environmental sciences students
Connectivity, neutral theories and the assessment of species vulnerability to global change in temperate estuaries
One of the main adaptation strategies to global change scenarios, aiming to preserve ecosystem functioning and biodiversity, is to maximise ecosystem resilience. The resilience of a species metapopulation can be improved by facilitating connectivity between local populations, which will prevent demographic stochasticity and inbreeding. The objective of this investigation is to estimate the degree of connectivity among estuarine species along the north-eastern Iberian coast, in order to assess community vulnerability to global change scenarios. To address this objective, two connectivity proxy types have been used based upon genetic and ecological drift processes: 1) DNA markers for the bivalve cockle (Cerastoderma edule) and seagrass Zostera noltei, and 2) the decrease in the number of species shared between two sites with geographic distance; neutral biodiversity theory predicts that dispersal limitation modulates this decrease, and this has been explored in estuarine plants and macroinvertebrates. Results indicate dispersal limitation for both saltmarsh plants and seagrass beds community and Z. noltei populations; this suggests they are especially vulnerable to expected climate changes on their habitats. In contrast, unstructured spatial pattern found in macroinvertebrate communities and in C. edule genetic populations in the area suggests that estuarine soft-bottom macroinvertebrates with planktonic larval dispersal strategies may have a high resilience capacity to moderate changes within their habitats. Our findings can help environmental managers to prioritise the most vulnerable species and habitats to be restored
Improving broiler performance at market age regardless of stocking density by using a pre-starter diet
Altres ajuts: Centro para el Desarrollo Tecnológico Industrial CDTI project IDI-20180885Broiler early nutrition has caught the attention of nutritionists due to the positive correlation between early growth rate and market weight. Early nutrition strategies such as low Ca levels or the use of highly digestible ingredients (e.g., spray-dried porcine plasma [SDPP]) have been reported to improve gut and muscle development, immunity, and overall growth of the bird. On the other hand, recent works suggested that stocking density represents the main constrain for modern chickens to express their full genetic potential. The current study aimed to elucidate the potential effects of pre-starter feeding strategies on contrasting livestock stocking densities. The study followed a factorial design of 2 contrasting starter programs (standard [0-11d] vs. pre-starter [0-4 d] + standard [4-11 d]) by 3 stocking densities (low, medium, and high, 27, 33, and 39 kg/BW/m, respectively). Birds placed at low stocking density showed higher BW and better FCR than those at high stocking density (P < 0.05) being this evident only after d 28. On the other hand, birds fed on pre-starter diet led to higher BW at 4 d (P < 0.001) and the effects on BW were maintained until market age (+2.54%; P < 0.05). The pre-starter diet also led to heavier carcasses (+2.2%; P < 0.05), improved uniformity (P < 0.10) and showed a lower incidence of lameness at high stocking densities (P < 0.05) compared to birds fed the standard starter diet. Results of the current study confirm that, regardless of the stocking density used, pre-starter diets (0-4 d) could lead to a better early growth and market weight
Effect of Chain Polydispersity on the Elasticity of Disordered Polymer Networks
Due to their unique structural and mechanical properties, randomly cross-linked polymer networks play an important role in many different fields, ranging from cellular biology to industrial processes. In order to elucidate how these properties are controlled by the physical details of the network (e.g., chain-length and end-to-end distributions), we generate disordered phantom networks with different cross-linker concentrations C and initial densities ρinit and evaluate their elastic properties. We find that the shear modulus computed at the same strand concentration for networks with the same C, which determines the number of chains and the chain-length distribution, depends strongly on the preparation protocol of the network, here controlled by ρinit. We rationalize this dependence by employing a generic stress-strain relation for polymer networks that does not rely on the specific form of the polymer end-to-end distance distribution. We find that the shear modulus of the networks is a nonmonotonic function of the density of elastically active strands, and that this behavior has a purely entropic origin. Our results show that if short chains are abundant, as it is always the case for randomly cross-linked polymer networks, the knowledge of the exact chain conformation distribution is essential for correctly predicting the elastic properties. Finally, we apply our theoretical approach to literature experimental data, qualitatively confirming our interpretations
Link between morphology, structure and interactions of composite microgels
We combine small angle scattering experiments and simulations to investigate
the internal structure and interactions of composite
Poly(N-isopropylacrylamide)-Poly(ethylene glycol) (PNIPAM-PEG) microgels. At
low temperatures the experimentally determined form factors and the simulated
density profiles indicate a loose internal particle structure with an extended
corona, that can be modeled as a star-like object. Increasing temperature
across the volumetric phase transition, the form factor develops an inflection
which, using simulations, is interpreted as arising from a configuration in
which PEG chains are incorporated in the interior of the PNIPAM network. In
this configuration a peculiar density profile characterized by two dense,
separate regions is observed, at odds with configurations in which the PEG
chains reside on the surface of the PNIPAM core. The conformation of the PEG
chains have also profound effects on the interparticle interactions: While
chains on the surface reduce the solvophobic attractions typically experienced
by PNIPAM particles at high temperatures, PEG chains inside the PNIPAM network
shift the onset of attractive interaction at even lower temperatures. Our
results show that by tuning the morphology of the composite microgels we can
qualitatively change both their structure and their mutual interactions,
opening the way to explore new collective behaviors of these objects.Comment: Manuscript 35 pages, 6 figures; Supplementary material 4 pages, 3
figure
Different lesion distribution in calves orally or intratracheally challenged with Mycobacterium bovis: implications for diagnosis
[EN] Animal tuberculosis (TB) remains a major problem in some countries despite the existence of control programmes focused mainly on cattle. In this species, aerogenous transmission is accepted as the most frequent infection route, affecting mainly the respiratory system. Under the hypothesis that the oral route could be playing a more relevant role in transmission, diagnosis and disease persistence than previously thought, this study was performed to assess the course of TB infection in cattle and its effects on diagnosis depending on the route of entry of Mycobacterium bovis. Two groups of five calves each were either endotracheally (EC) or orally (OC) challenged. Necropsies were carried out 12 weeks after challenge except for three OC calves slaughtered 8 weeks later. All animals reacted to the tuberculin skin test and the entire EC group was positive to the interferon-gamma release assay (IGRA) 2 weeks after challenge and thereafter. The first positive IGRA results for OC calves (3/5) were recorded 4 weeks after challenge. Group comparison revealed significant differences in lesion and positive culture location and scoring. TB-compatible gross lesions and positive cultures were more frequently found in the thorax (p < 0.001) and lung (p < 0.05) of EC animals, whereas OC animals presented lesions (p = 0.23) and positive cultures (p < 0.05) mainly located in the abdomen. These results indicate that the infection route seems to be a determining factor for both the distribution and the time needed for the development of visible lesions. Our study suggests that confirmation of TB infection in some skin reactor animals can be problematic if current post-mortem examination and diagnostics are not improvedSIThis study was supported with funds from the Spanish Ministry of Economy and Competitiveness (Research Project AGL2014-56305-C3-3-R) and the Department of Economic Development and Competitiveness of the Basque Government. MS holds a fellowship from the Department of Education of the Basque Government (PRE_2017_2_0043
The journey towards elimination of gambiense human African trypanosomiasis: not far, nor easy
Considering the epidemic situation of gambiense human African trypanosomiasis (HAT) at the end of the twentieth century, the World Health Organization (WHO) and partners strengthened disease control and surveillance. Over the last 15 years, the activities implemented through the National Control Programmes have brought gambiense HAT under control and now its elimination is deemed as an achievable goal. In 2012, WHO targeted gambiense HAT for elimination as a public health problem by 2020. The final goal will be the sustainable disease elimination by 2030, defined as the interruption of the transmission of gambiense HAT. The elimination is considered feasible, because of the epidemiological vulnerability of the disease, the current state of control, the availability of strategies and tools and international commitment and political will. Integration of activities in the health system is needed to ensure the sustainability of the elimination. The development of user-friendly diagnostic and treatment tools will facilitate the integration process. Adequate funding is needed to implement activities, but also to support research that will make the elimination sustainable. A long-term commitment by donors is needed and ownership of the process by endemic countries is critica
Efecto de amortiguamiento térmico de una barrera verde de Arundo donax como elemento de bioclimatización en edificios
Among the main environmental impacts of the operation of residential buildings are those due to greenhouse gases generation as a result of electric consumption of air conditioning systems. The use of vegetation systems in residential buildings represents an alternative to reduce this energy consumption. Green vegetation systems barriers are often used as protection against winds, but recently they are also being used as acoustic dampers. This work explores their use as thermal insulation systems for buildings. Specifically, we report the behavior of an Arundo donax green barrier as a bioclimatic element. The results are analyzed based on indoor and outdoor temperature measurement in prototype buildings, in function of the green barrier presence. Additionally Arundo donax transpiration under extreme environmental conditions was determined.Entre los principales impactos ambientales derivados de la operación de edificios habitacionales está la generación de gases de efecto invernadero resultante del consumo eléctrico de sistemas de climatización. El uso de sistemas de vegetación representa una alternativa para disminuir dicho consumo energético. Las barreras verdes son sistemas de vegetación empleados como protección contra el viento, aunque recientemente se ha explorado su uso como sistemas de amortiguación acústica. En este trabajo se analiza su posible aplicación como sistemas de aislamiento térmico para edificios. En específico, se reporta el comportamiento de una barrera verde de Arundo donax como elemento de bioclimatización. Los resultados se analizan a partir de las temperaturas medidas en el interior y exterior de edificios prototipo, en función de la presencia de una barrera verde. Adicionalmente se determinó la traspiración del Arundo donax en condiciones ambientales extremas
Strategy towards Replacing Pork Backfat with a Linseed Oleogel in Frankfurter Sausages and Its Evaluation on Physicochemical, Nutritional, and Sensory Characteristics
Different health institutions from western countries ha–ve recommended a diet higher in polyunsaturated fats, especially of the n-3 family. However, this is not a trivial task, especially for meat-processing sectors. The objective of this work was to assess the influence of replacing pork backfat with linseed oleogel on the main quality parameters of frankfurters. The frankfurters were formulated by the pork backfat replacement of 0% (control), 25% (SF-25), and 50% (SF-50), using a linseed oleogel gelled with beeswax. The determination of quality parameters (pH, colour, chemical composition, and texture parameters), the fatty acid profile, and the sensory evaluation was carried out for each batch. The fatty acid profile was substantially improved, and the saturated fatty acid (SFA) content was reduced from 35.15g/100g in control sausages to 33.95 and 32.34g/100 g in SF-25 and SF-50, respectively, and more balanced ratios n-6/n-3 were achieved. In addition, the sausages with linseed oleogel also decreased the cholesterol content from 25.08 mg/100 g in control sausages to 20.12 and 17.23 mg/100 g in SF-25 and SF-50, respectively. It may therefore be concluded that these innovative meat products are a healthier alternative. However, sensory parameters should be improved in order to increase consumer acceptability, and further research is needed.Artur Martins is the recipient of a fellowship supported by a doctoral advanced training (call NORTE-69-2015-15) funded by the European Social Fund under the scope of Norte2020—Programa Operacional Regional do Norte. Jose M. Lorenzo is a member of the HealthyMeat network, funded by CYTED (ref. 119RT0568). Thanks to GAIN (Axencia Galega de Innovación) for supporting this research (grant number IN607A2019/01)S
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