1,204 research outputs found
¿Está afectando la actividad turística creciente a la distribución o al número de parejas reproductoras de una pequeña colonia de halcón de Eleonora?
Human disturbance is a common threat for species of conservation concern such as the Eleonora’s Falcon. This paper shows that the rise in tourist presence from 1992 to 2000 has not affected the overall number of breeding pairs or their productivity in a small archipelago of the western Mediterranean (Columbretes Islands). However, the increasing tourist activity has coincided with a shift in the degree of occupancy on two islands within the archipelago, favouring that with a lower human presence close to colonies. Several conservation actions are reported and suggested, aimed at both testing and preventing the role of human presence as a factor influencing long–term colony persistence and growth.Las perturbaciones de origen antrópico son un factor de amenaza común para especies vulnerables como el halcón de Eleonora. El presente artículo muestra que el incremento de la presencia humana en un archipiélago del Mediterráneo occidental (islas Columbretes), durante el periodo 1992–2000, no ha afectado ni al número de parejas nidificantes ni a su productividad. Sin embargo, dicho incremento de la actividad turística ha coincidido con un cambio en el nivel de ocupación de dos islas del archipiélago, favoreciendo a la isla menos frecuentada por embarcaciones turísticas. Se sugieren algunas medidas de gestión que pueden servir para comprobar si las visitas turísticas pueden influir en el mantenimiento y crecimiento de la colonia a largo plazo, así como para prevenir estos posibles efectos
Mechanosensitive Self-Replication Driven by Self-Organization
Self-replicating molecules are likely to have played an important role in the origin of life, and a small number of fully synthetic self-replicators have already been described. Yet it remains an open question which factors most effectively bias the replication toward the far-from-equilibrium distributions characterizing even simple organisms. We report here two self-replicating peptide-derived macrocycles that emerge from a small dynamic combinatorial library and compete for a common feedstock. Replication is driven by nanostructure formation, resulting from the assembly of the peptides into fibers held together by β sheets. Which of the two replicators becomes dominant is influenced by whether the sample is shaken or stirred. These results establish that mechanical forces can act as a selection pressure in the competition between replicators and can determine the outcome of a covalent synthesis.
Highly Reliable and Repeatable Soldering Technique for Assembling Empty Substrate Integrated Waveguide Devices
[EN] In this paper, a novel mymargin soldering technique that improves the fabrication process of empty substrate integrated waveguide (ESIW) devices is presented. Up until now, in order to fabricate an ESIW device, the tin solder paste was distributed, before assembling, on the contact surface between layers, in order to ensure a good electrical contact. This process has a low degree of repeatability (random soldering thickness and distribution of tin) and reliability (a significant number of nonworking prototypes due to tin overflow). In this paper, we propose the mechanization of a set of plated vias just next to the metalized walls of the ESIW in the central layer. Next, in the top and bottom covers that close this ESIW, additional plated vias are drilled in the same position so that, when the device is assembled (using screws or rivets), metalized holes can be seen passing through the whole structure from top to bottom. These holes are then used as soldering vias that can guide the tin paste straight to the point where it is needed. When the paste is dried, soldered vias ensure a very good electrical contact between layers. In addition, the fluid tin fills any small gap that appears between layers, thus providing a very good electrical contact and mechanical union. This novel soldering technique has been validated with experimental results. Several prototypes of filters centered at 13 and 35 GHz have been fabricated, proving the repeatability and reliability of the proposed soldering technique.This work was supported by the Ministerio de Economiy Competitividad, Spanish Government, under Project TEC2016-75934-C4-3-R and Project TEC2016-75934-C4-1-R.Martinez, JA.; Belenguer, A.; Esteban González, H. (2019). Highly Reliable and Repeatable Soldering Technique for Assembling Empty Substrate Integrated Waveguide Devices. IEEE Transactions on Components, Packaging and Manufacturing Technology (Online). 9(11):2276-2281. https://doi.org/10.1109/TCPMT.2019.2915688S2276228191
Thru reflect line calibration for empty substrate integrated waveguide with microstrip transitions
In past years, a great number of substrate integrated circuits have been developed. Among these new transmission lines, the substrate integrated waveguide (SIW) has received special attention. Although the quality factor and losses of these new integrated lines are better than the planar circuits, these characteristics are worst than in the case of waveguides, mainly due to the presence of dielectric substrate. To improve the performance of the integrated circuits, a new methodology for manufacturing the empty waveguides, without dielectric substrate, but at the same time completely integrated in a planar substrate, has been recently proposed, resulting in the novel empty SIW (ESIW). A low-cost and easy to manufacture thru reflect line calibration kit for de-embedding the effect of connectors and transitions when measuring ESIW devices is presented. Results prove the high quality of this calibration kit.Fernández Berlanga, M.; Ballesteros Garrido, J.; Martínez Cano, L.; Esteban González, H.; Belenguer Martínez, A. (2015). Thru reflect line calibration for empty substrate integrated waveguide with microstrip transitions. Electronics Letters. 51(16):1274-1276. doi:10.1049/el.2015.1393S127412765116Belenguer, A., Esteban, H., & Boria, V. E. (2014). Novel Empty Substrate Integrated Waveguide for High-Performance Microwave Integrated Circuits. IEEE Transactions on Microwave Theory and Techniques, 62(4), 832-839. doi:10.1109/tmtt.2014.2309637Deslandes, D., & Ke Wu. (2005). Analysis and design of current probe transition from grounded coplanar to substrate integrated rectangular waveguides. IEEE Transactions on Microwave Theory and Techniques, 53(8), 2487-2494. doi:10.1109/tmtt.2005.852778Engen, G. F., & Hoer, C. A. (1979). Thru-Reflect-Line: An Improved Technique for Calibrating the Dual Six-Port Automatic Network Analyzer. IEEE Transactions on Microwave Theory and Techniques, 27(12), 987-993. doi:10.1109/tmtt.1979.1129778Caballero, E. D., Boria, V. E., Belenguer, A., & Esteban, H. (2013). Thru-reflect-line calibration for substrate integrated waveguide devices with tapered microstrip transitions. Electronics Letters, 49(2), 132-133. doi:10.1049/el.2012.302
Presència del gat domèstic, Felis silvestris catus (Schreber, 1775), i del gat serval, Felis silvestris, en un espai natural protegit: el cas del Parc Natural Serra de Mariola (sud-est espanyol)
Presencia del gato doméstico, Felis silvestris catus (Schreber, 1775), y del gato montés, Felis silvestris, en un espacio natural protegido: el caso del Parque Natural Serra de Mariola (sureste español) El principal objetivo de esta investigación es conocer aspectos ecológicos, de distribución e impactos del gato doméstico dentro de la sierra de Mariola. El área de estudio es un parque natural de 17.500 hectáreas situado en el sur del País Valenciano. Un mejor conocimiento de su distribución será de interés para la definición de medidas de gestión de fauna del parque. Utilizando técnicas de fototrampeo se recopilaron 29.941 imágenes con algún contacto animal. El 0,62% de las fotografías registradas son de gato doméstico, de manera que se ha detectado su presencia en 29 de las 63 cuadrículas (2 x 2 km) del Parque Natural Serra de Mariola (el 46,03%). El periodo de muestreo se prolongó desde enero hasta septiembre de 2010. Este estudio ha permitido integrar la información recopilada en el campo en bases de datos a fin de evaluar la presencia del gato doméstico en la sierra de Mariola. Datos publicados en GBIF (doi:10.15470/p7evig).Presence of domestic cat, Felis silvestris catus (Schreber, 1775), and wild cat, Felis silvestris, in a natural protected area: the case of Serra de Mariola Natural Park (SE of Spain)The main objective of this research was to determine the ecological aspects, distribution, and impact of domestic cat in the Serra de Mariola. The study area is a natural park of 17,500 hectares located in the south of the Valencia Community. Better knowledge of the distribution of this cat will help define management measures in the park. Using camera traps, we collected 29,941 images of animal contact. A total of 0.62% of these photographs were of domestic cat, the presence of which was detected in 29 of 63 grids (2 x 2 km) in Serra de Mariola Natural Park (46.03%). Sampling was performed from January to September 2010. The study allowed us to integrate the information collected in the field into databases and to evaluate the presence of domestic cat in the Serra de Mariola.Data published through GBIF (doi:10.15470/p7evig).El principal objectiu d’aquesta recerca és conèixer aspectes ecològics, de distribució i d’impactes del gat domèstic dins de la serra de Mariola. L’àrea d’estudi és un parc natural de 17.500 hectàrees situat al sud del País Valencià. Un millor coneixement de la distribució serà d’interès per a la definició de mesures de gestió de fauna del parc. Utilitzant tècniques de fototrampeig es van recopilar 29.941 imatges amb algun contacte animal. El 0,62% de les fotografies enregistrades són de gat domèstic, de manera que se n’ha detectat la presència en 29 de les 63 quadrícules (2 x 2 km) del Parc Natural de la Serra de Mariola (el 46,03%). El període de mostreig es va prolongar des de gener fins a setembre de 2010. Aquest estudi ha permès integrar la informació recopilada al camp en bases de dades per avaluar la presència del gat domèstic a la serra de Mariola. Dades publicades a GBIF (doi:10.15470/p7evig)
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Analytical studies of some agents for fertility regulation (Volume 1)
This Thesis describes three pieces of work, all of which were commissioned by the World Health Organization Special Programme in Human Reproduction which are concerned with aspects of the chemistry of agents for the regulation of fertility. The first two topics are related to agents causing infertility in the male, whilst the third is related to a method of contraceptive delivery in the female.
Gossypol is a chiral natural product with phenolic and aldehyde functionality, occurring in the cotton plant. The literature on the isolation, identification, chemistry and biological properties of gossypol is reviewed in this Thesis. Following reports by Chinese scientists that racemic gossypol causes reversible infertility in male animals and human beings, it became clear from further studies in both China and in Western countries that toxic side effects were seen on prolonged dosing. In an attempt to lower the toxicity of this interesting antispermatogenic agent, attention turned to studies of the individual enantiomers, which were first separated in Matlin' s group by derivatisation with a chiral amine and chromatography of the resulting diastereomeric Schiff's bases on a non-chiral (normal or reverse) phase. Following hydrolysis and fractional crystallization, 40 g of chemically and optically pure (-)-gossypol was prepared and micronized for a toxicology study.
Extracts of Tripterygium wilfordii L. Hook have been used in Traditional Chinese Medicine for many centuries for the treatment of inflammatory and dermatological disorders. Recent studies in China have revealed that men undergoing prolonged treatment with tabletted extracts of T. wilfordii suffered a reversible loss of fertility and tests in male rats have shown that this is related to a dramatic reduction in sperm density and motility. This Thesis gives a literature review of all the known constituents of T. wilfordii and the biological studies which have been reported. Furthermore, it describes a detailed bioassay-directed sub-fractionation of both T. wilfordii tablets and of crude extracts of the plant, obtained from China. This work led to the isolation and identification of a series of diterpene epoxides, including the known triptolide and tripdiolide and some isomers of the latter, one of which is a new compound, which show varying degrees of activity as oral anti-spermatogenic agents in male rats. Extensive use was made of analytical and preparative HPLC and of spectroscopic techniques, including high field NMR and mass spectrometry, in accomplishing the identification of the antifertility constituents of T.wilfordii.
In the final part of the Thesis, a literature review is presented of the design, mode of action and clinical studies of vaginal rings. These are slow-release drug delivery systems in which a contraceptive steroid is contained within a polymer ring and is released by diffusion processes at a slow rate for prolonged periods of time. The Thesis then describes experimental studies in which suitable, constant eluent conditions and analytical procedures were developed and successfully applied. Release rates were measured for two types of newly fabricated rings, designed to release either progesterone or levonorgestrel at a near constant rate for periods of three months. For both steroids, it was possible to show that release could be described mathematically by a simple diffusion-distance model and that reproducible in vitro release rates could be obtained for devices in which a fixed loading of steroid is dispersed within a polymer core surrounded by an outer polymer sheath. Suitable dimensions were selected for the production of rings providing an initial release rate of 5 mg/day of progesterone and quality control was carried out on four batches of these rings fabricated by Dow Corning Ltd for WHO clinical trials. Similarly, suitable ring dimensions were selected for the production of rings providing an initial release rate of 20 ug/day of levonorgestrel and the production of these rings for clinical use in Britain and other countries is now being undertaken by Roussel Laboratories
Tetraparesia asociada a lesiones óseas agresivas y generalizadas en una perra con leishmaniosis
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Analytical studies of some agents for fertility regulation (Volume 2)
This Thesis describes three pieces of work, all of which were commissioned by the World Health Organization Special Programme in Human Reproduction which are concerned with aspects of the chemistry of agents for the regulation of fertility. The first two topics are related to agents causing infertility in the male, whilst the third is related to a method of contraceptive delivery in the female.
Gossypol is a chiral natural product with phenolic and aldehyde functionality, occurring in the cotton plant. The literature on the isolation, identification, chemistry and biological properties of gossypol is reviewed in this Thesis. Following reports by Chinese scientists that racemic gossypol causes reversible infertility in male animals and human beings, it became clear from further studies in both China and in Western countries that toxic side effects were seen on prolonged dosing. In an attempt to lower the toxicity of this interesting antispermatogenic agent, attention turned to studies of the individual enantiomers, which were first separated in Matlin' s group by derivatisation with a chiral amine and chromatography of the resulting diastereomeric Schiff's bases on a non-chiral (normal or reverse) phase. Following hydrolysis and fractional crystallization, 40 g of chemically and optically pure (-)-gossypol was prepared and micronized for a toxicology study.
Extracts of Tripterygium wilfordii L. Hook have been used in Traditional Chinese Medicine for many centuries for the treatment of inflammatory and dermatological disorders. Recent studies in China have revealed that men undergoing prolonged treatment with tabletted extracts of T. wilfordii suffered a reversible loss of fertility and tests in male rats have shown that this is related to a dramatic reduction in sperm density and motility. This Thesis gives a literature review of all the known constituents of T. wilfordii and the biological studies which have been reported. Furthermore, it describes a detailed bioassay-directed sub-fractionation of both T. wilfordii tablets and of crude extracts of the plant, obtained from China. This work led to the isolation and identification of a series of diterpene epoxides, including the known triptolide and tripdiolide and some isomers of the latter, one of which is a new compound, which show varying degrees of activity as oral anti-spermatogenic agents in male rats. Extensive use was made of analytical and preparative HPLC and of spectroscopic techniques, including high field NMR and mass spectrometry, in accomplishing the identification of the antifertility constituents of T.wilfordii.
In the final part of the Thesis, a literature review is presented of the design, mode of action and clinical studies of vaginal rings. These are slow-release drug delivery systems in which a contraceptive steroid is contained within a polymer ring and is released by diffusion processes at a slow rate for prolonged periods of time. The Thesis then describes experimental studies in which suitable, constant eluent conditions and analytical procedures were developed and successfully applied. Release rates were measured for two types of newly fabricated rings, designed to release either progesterone or levonorgestrel at a near constant rate for periods of three months. For both steroids, it was possible to show that release could be described mathematically by a simple diffusion-distance model and that reproducible in vitro release rates could be obtained for devices in which a fixed loading of steroid is dispersed within a polymer core surrounded by an outer polymer sheath. Suitable dimensions were selected for the production of rings providing an initial release rate of 5 mg/day of progesterone and quality control was carried out on four batches of these rings fabricated by Dow Corning Ltd for WHO clinical trials. Similarly, suitable ring dimensions were selected for the production of rings providing an initial release rate of 20 ug/day of levonorgestrel and the production of these rings for clinical use in Britain and other countries is now being undertaken by Roussel Laboratories
Effects of maternal subnutrition during early pregnancy on cow hematological profiles and offspring physiology and vitality in two beef breeds
This experiment evaluated the effects of subnutrition during early gestation on hematology in cows (Bos Taurus) and on hematological, metabolic, endocrine, and vitality parameters in their calves. Parda de Montaña and Pirenaica dams were inseminated and assigned to either a control (CONTROL, 100% requirements) or a nutrient‐restricted group (SUBNUT, 65%) during the first third of gestation. Dam blood samples were collected on days 20 and 253 of gestation, and calf samples were obtained during the first days of life. Pirenaica dams presented higher red series parameters than Parda de Montaña dams, both in the first and the last months of gestation. During early pregnancy, granulocyte numbers and mean corpuscular hemoglobin were lower in Pirenaica‐SUBNUT than in Pirenaica‐CONTROL cows. Calves from the SUBNUT cows did not show a physiological reduction in red series values in early life, suggesting later maturation of the hematopoietic system. Poor maternal nutrition affected calf endocrine parameters. Newborns from dystocic parturitions showed lower NEFA concentrations and weaker vitality responses. In conclusion, maternal nutrition had short‐term effects on cow hematology, Pirenaica cows showing a higher susceptibility to undernutrition; and a long‐term effect on their offspring endocrinology, SUBNUT newborns showing lower levels of IGF‐1 and higher levels of cortisol.This work was supported by the Spanish Ministry of Economy and Business and the European Union Regional Development Funds (INIA RTA 2013‐00059‐C02 and INIA RZP 2015‐001) and the Government of Aragon under the Grant Research Group Funds (A14_17R). A. Noya received a PhD grant from INIA‐Government of Aragon
Efecto del sexo y del peso al sacrificio sobre las características del lomo y de la grasa de cerdos destinados a la producción de Jamón curado de Teruel
A total of 200 Duroc × (Landrace × Large White) pigs intended for Protected Designation of Origin Teruel dry-curedham manufacture was used for the study. The objective was to investigate the effect of gender (barrows and gilts) andslaughter weight (SW; 120, 125, 130, 135 or 140 kg) on Longissimus dorsi (LD) muscle characteristics and the fatty acid (FA) profile of the subcutaneous fat. The LD from barrows had higher intramuscular fat (P<0.01), b* value (P<0.01),colour intensity (P<0.01 for c* and P<0.05 for Hº) and tenderness (P<0.05) than the LD from gilts. Fat from barrows had a higher saturated FA content (P<0.01) a lower polyunsaturated (P<0.001) and unsaturated FA content (P<0.01) than fat from gilts. On the other hand, intramuscular fat was increased (P<0.05) but moisture and L* (P<0.05), thawing (P<0.001) and cooking losses (P<0.01) decreased as SW increased. Polyunsaturated FA content decreased (P<0.001) and saturated FA proportion tended to increase (P<0.10) as the SW increased. It was concluded that barrows and gilts were adequate for both fresh meat and dry-cured ham production. An increase in SW from 120 to 140 kg impairs subcutaneous fat quality but improves some loin characteristics which are desirable for Teruel dry-cured pork production.Un total de 200 cerdos Duroc × (Landrace × Large) destinados a la Denominación de Origen Protegida Jamón de Teruelfueron usados para el estudio. El objetivo fue estudiar el efecto del sexo (machos castrados y hembras) y el peso al sacrificio (120, 125, 130, 135 y 140 kg) sobre las características del músculo Longissimus dorsi (LD) y el perfil de ácidos grasos de la grasa subcutánea. El LD de los castrados presentó mayor contenido en grasa intramuscular (P<0,01), valor de b* (P<0,01), intensidad del color (P<0,01 para c* y P<0,05 para Hº) y terneza (P<0,05) que el LD de las hembras. La grasa de los castrados tuvo mayor porcentaje de ácidos grasos saturados (P<0,01) y menor de poliinsaturados (P<0,001) e insaturados (P<0,01) que la grasa de las hembras. El aumento del peso al sacrificio incrementó el contenido en grasa intramuscular (P<0,05), pero redujo la humedad y el valor L* (P<0,05) y las pérdidas por descongelación (P<0,001) y por cocinado (P<0,01) del lomo. Asimismo, el contenido en ácidos grasos poliinsaturados disminuyó (P<0,001) y la proporción deácidos grasos saturados tendió a aumentar (P<0,10) a medida que el peso al sacrificio aumentaba. Concluimos que machos castrados y hembras son adecuados para carne fresca y para la elaboración de productos curados. El incremento del peso al sacrificio empeora la calidad de la grasa, pero mejora algunos aspectos de la carne que son deseables para la industria de carne curada de cerdo de Teruel
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