2,027 research outputs found
The space exploration initiative. Operational efficiency panel space-basing technology requirements
The topics covered include the following: (1) space basing technology requirements sources; (2) orbit transfer vehicle (OTV) processing heritage; (3) ground processing progression to space processing; (4) technology requirements for space based OTV servicing and maintenance; (5) design and development schedule for OTV's and OTV accommodations/ support hardware; (6) cryogenic technology test program development; (7) cryogenic propellant transfer, storage, and reliquefaction management summary; (8) propellant transfer technology analysis and ground testing; (8) OTV propellant storage depot development critical scaling relationships; (9) flight experiment options; (10) OTV maintenance; (11) automated fault detection/ isolation and system checkout summary; (12) engine replacement; (13) alternative docking operation; (14) OTV/payload integration; and (15) technology criticality and capability assessment. This document is presented in viewgraph form
Transgenic citrus plants expressing the citrus tristeza virus p23 protein exhibit viral-like symptoms
The 23 kDa protein (p23) coded by the 3'-terminal gene of Citrus tristeza virus (CTV), a member of the genus Closterovirus with the largest genome among plant RNA viruses, is an RNA-binding protein that contains a motif rich in cysteine and histidine residues in the core of a putative zinc-finger domain. On this basis, a regulatory role for CTV replication or gene expression has been suggested for p23. To explore whether over-expression of this protein in transgenic plants could affect the normal CTV infection process, transgenic Mexican lime plants were generated carrying the p23 transgene, or a truncated version thereof, under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Constitutive expression of p23 induced phenotypic aberrations that resembled symptoms incited by CTV in non-transgenic lime plants, whereas transgenic plants expressing the p23 truncated version were normal. The onset of CTV-like symptoms in p23 transgenic plants was associated with the expression of p23, and its accumulation level paralleled the intensity of the symptoms. This demonstrates that p23 is involved in symptom development and that it most likely plays a key role in CTV pathogenesis. This is the first case in which a protein encoded by a woody plant-infecting RNA virus has been identified as being directly involved in pathogenesis in its natural host. This finding also delimits a small region of the large CTV genome for the future mapping of specific pathogenic determinants
Cylindrical and Powell liquid crystal lenses with positive-negative optical power
We demonstrate a technique to engineer cylindrical and Powell liquid crystal lenses with positive or negative optical power. The device is based on two indium-tin-oxide electrode combs and a microstructured voltage transmission electrode. The technique features the advantages of a multielectrode lens, albeit using a single lithographic step and only two voltage sources. Extensive control of the phase profile across the device active area is demonstrated, achieving both positive and negative optical power. The lens aperture is not constrained by the geometrical parameters and can be scaled to larger values.This work was supported in part by the Comunidad de Madrid and FEDER Program under Grant S2018/NMT-4326, in part by the Ministerio de Economía y Competitividad of Spain under Grant TEC2013-47342-C2-2-R
and Grant TEC2016-76021-C2-2-R, in part by the FEDER/Ministerio de Ciencia, Innovación y Universidades and Agencia Estatal de Investigación under Grant RTC2017-6321-1, Grant PID2019-109072RB-C31, and Grant PID2019-107270RB-C21, in part by the Ministry of National Defense of Poland under Grant GBMON/13-995/2018/WAT, and in part by the Military University of Technology under Grant 23-895
Positive-negative tunable liquid crystal lenses based on a microstructured transmission line
In this work, a novel technique to create positive-negative tunable liquid crystal lenses is proposed and experimentally demonstrated. This structure is based on two main elements, a transmission line acting as a voltage divider and concentric electrodes that distribute the voltage homogeneously across the active area. This proposal avoids all disadvantages of previous techniques, involving much simpler fabrication process (a single lithographic step) and voltage control (one or two sources). In addition, low voltage signals are required. Lenses with switchable positive and negative focal lengths and a simple, low voltage control are demonstrated. Moreover, by using this technique other optical devices could be engineered, e.g. axicons, Powell lenses, cylindrical lenses, Fresnel lenses, beam steerers, optical vortex generators, etc. For this reason, the proposed technique could open new venues of research in optical phase modulation based on liquid crystal materials.This work was supported by Comunidad de Madrid and FEDER Program (S2018/NMT-4326), the Ministerio
de Economía y Competitividad of Spain (TEC2016-77242-C3-1-R and TEC2016-76021-C2-2-R), the FEDER/
Ministerio de Ciencia, Innovación y Universidades and Agencia Estatal de Investigación (RTC2017-6321-1).
Also, the Ministry of National Defense of Poland (GBMON/13-995/2018/WAT)
Acute health effects after accidental exposure to styrene from drinking water in Spain
OBJECTIVES: We studied subjective health symptoms in a population accidentally exposed to high styrene concentrations in drinking tap water. The contamination occurred during the reparation of a water tank. METHODS: Residents of 27 apartments in two buildings using the contaminated water were contacted. A questionnaire on subjective symptoms was administered to 84 out of 93 persons living in the apartments at the time of the accident. Styrene concentration was measured in samples of water collected two days after the accident. The means of exposure associated with appearance of symptoms were examined through case-control analyses. RESULTS: Styrene in water reached concentrations up to 900 μg/L. Symptoms were reported by 46 persons (attack rate 55 %). The most frequent symptoms were irritation of the throat (26%), nose (19%), eyes (18%) and the skin (14%). General gastrointestinal symptoms were observed with 11% reporting abdominal pain and 7% diarrhea. The factors most strongly associated with symptoms were drinking tap water (OR = 7.8, 95% CI 1.3–48), exposure to vapors from the basement (OR = 10.4, 2.3–47) and eating foods prepared with tap water (OR = 8.6, 1.9–40). All residents in the ground floor reported symptoms. CONCLUSIONS: This accidental contamination led to very high styrene concentrations in water and was related to a high prevalence of subjective symptoms of the eyes, respiratory tract and skin. Similar exposures have been described in workers but not in subjects exposed at their residence. Various gastrointestinal symptoms were also observed in this population probably due to a local irritative effect
FishPath: computer application for design of vertical slot fishways
[EN] Vertical slot fishways are hydraulic structures designed to allow fish migration through obstacles in rivers. The appropriate design of these devices depends on an interplay between hydraulic and biological variables, since the hydrodynamic properties of the fishway must meet the requirements of the fish species for which it is intended. This paper presents a computer application to analyze the efficiency of a fishway model according to biological criteria. The proposed model applies restrictions relative to the swimming capacity of fish, their depth requirements and their needs regarding turbulent energy dissipation. It allows the objective comparison of designs and the determination of which is to be more efficient. It is expected that the application can provide guidance to the technicians involved in fishway design regarding the systematic application of hydrobiological criteria, which also incorporate the latest research findings in this field.[ES] Las escalas de peces de hendidura vertical son estructuras hidráulicas diseñadas para permitir la migración de las especies piscícolas a través de obstáculos en ríos. El diseño adecuado de estos dispositivos depende de la interacción entre variables hidráulicas y biológicas, dado que las propiedades hidrodinámicas de la escala deben ajustarse a los requisitos de las especies objetivo. En este artículo se presenta una aplicación informática que analiza la eficiencia de un modelo de escala de acuerdo con criterios biológicos. El modelo propuesto aplica restricciones referidas a la capacidad de natación de los peces, a sus necesidades de calado y a sus requisitos en relación con la energía disipada en forma de turbulencias. Permite así comparar diseños de forma objetiva y determinar cuál será previsiblemente más eficiente. Con esta herramienta se busca facilitar a los técnicos involucrados en el diseño de escalas de peces de hendidura vertical la aplicación sistemática de criterios hidrobiológicos, que incorporen además los resultados de las investigaciones más recientes en este ámbito.Este trabajo ha sido parcialmente financiado por fondos FEDER y el Ministerio de Economía y Competitividad
(Ref. CGL2012-34688 y PCT-380000-2007-3). María Bermúdez expresa su agradecimiento al programa postdoctoral del Plan I2C
de la Xunta de Galicia (Ref. ED481B 2014/156-0).Bermúdez, M.; Rico, Á.; Rodríguez, Á.; Pena, L.; Rabuñal, JR.; Puertas, J.; Balairón, L.... (2015). FishPath: aplicación informática de diseño de escalas de peces de hendidura vertical. Ingeniería del Agua. 19(3):179-191. https://doi.org/10.4995/ia.2015.3655SWORD179191193ADF&G, Alaska Department of Fish and Game, and ADOT&PF, Alaska Department of Transportation and Public Facilities, (2001). Memorandum of Agreement between Alaska Department of Fish and Game and Alaska Department of Transportation and Public Facilities for the Design, Permitting, and Construction of Culverts for Fish Passage. Juneau.Aramburu, E., Morcillo, F., Castillo, M., Lara, A., Balairón, L. (2015). Análisis morfológico de las especies ensayadas en la escala de hendidura vertical del CEH-CEDEX para la definición de calados mínimos. Centro de Estudios y Experimentación de Obras Públicas. Informe interno.Aramburu, E., Morcillo, F., Castillo, M., Lara, A. (2014). 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New Mediterranean marine biodiversity records (December, 2013)
Based on recent biodiversity studies carried out in different parts of the Mediterranean, the following 19 species are included as new
records on the floral or faunal lists of the relevant ecosystems: the green algae Penicillus capitatus (Maltese waters); the nemertean Am-
phiporus allucens (Iberian Peninsula, Spain); the salp Salpa maxima (Syria); the opistobranchs Felimida britoi and Berghia coerulescens
(Aegean Sea, Greece); the dusky shark Carcharhinus obscurus (central-west Mediterranean and Ionian Sea, Italy); Randall’s threadfin
bream Nemipterus randalli, the broadbanded cardinalfish Apogon fasciatus and the goby Gobius kolombatovici (Aegean Sea, Turkey);
the reticulated leatherjack Stephanolepis diaspros and the halacarid Agaue chevreuxi (Sea of Marmara, Turkey); the slimy liagora Ganon-
ema farinosum, the yellowstripe barracuda Sphyraena chrysotaenia, the rayed pearl oyster Pinctada imbricata radiata and the Persian
conch Conomurex persicus (south-eastern Kriti, Greece); the blenny Microlipophrys dalmatinus and the bastard grunt Pomadasys incisus
(Ionian Sea, Italy); the brown shrimp Farfantepenaeus aztecus (north-eastern Levant, Turkey); the blue-crab Callinectes sapidus (Corfu,
Ionian Sea, Greece). In addition, the findings of the following rare species improve currently available biogeographical knowledge: the
oceanic pufferfish Lagocephalus lagocephalus (Malta); the yellow sea chub Kyphosus incisor (Almuñécar coast of Spain); the basking
shark Cetorhinus maximus and the shortfin mako Isurus oxyrinchus (north-eastern Levant, Turkey).peer-reviewe
Sustained Domestic Vector Exposure Is Associated With Increased Chagas Cardiomyopathy Risk but Decreased Parasitemia and Congenital Transmission Risk Among Young Women in Bolivia
Vector exposure showed a direct association with Chagas cardiomyopathy, but an inverse relationship with maternal parasitemia and congenital transmission. We hypothesize that repeated antigen exposure maintains an inflammatory response, increasing cardiomyopathy, but this upregulation improves control of parasitemia during pregnanc
Validation of Plasmodium falciparum dUTPase as the target of 5'-tritylated deoxyuridine analogues with anti-malarial activity
BACKGROUND: Malaria remains as a major global problem, being one of the infectious diseases that engender highest mortality across the world. Due to the appearance of resistance and the lack of an effective vaccine, the search of novel anti-malarials is required. Deoxyuridine 5'-triphosphate nucleotido-hydrolase (dUTPase) is responsible for the hydrolysis of dUTP to dUMP within the parasite and has been proposed as an essential step in pyrimidine metabolism by providing dUMP for thymidylate biosynthesis. In this work, efforts to validate dUTPase as a drug target in Plasmodium falciparum are reported. METHODS: To investigate the role of PfdUTPase in cell survival different strategies to generate knockout mutants were used. For validation of PfdUTPase as the intracellular target of four inhibitors of the enzyme, mutants overexpressing PfdUTPase and HsdUTPase were created and the IC50 for each cell line with each compound was determined. The effect of these compounds on dUTP and dTTP levels from P. falciparum was measured using a DNA polymerase assay. Detailed localization studies by indirect immunofluorescence microscopy and live cell imaging were also performed using a cell line overexpressing a Pfdut-GFP fusion protein. RESULTS:Different attempts of disruption of the dut gene of P. falciparum were unsuccessful while a 3' replacement construct could recombine correctly in the locus suggesting that the enzyme is essential. The four 5'-tritylated deoxyuridine analogues described are potent inhibitors of the P. falciparum dUTPase and exhibit antiplasmodial activity. Overexpression of the Plasmodium and human enzymes conferred resistance against selective compounds, providing chemical validation of the target and confirming that indeed dUTPase inhibition is involved in anti-malarial activity. In addition, incubation with these inhibitors was associated with a depletion of the dTTP pool corroborating the central role of dUTPase in dTTP synthesis. PfdUTPase is mainly localized in the cytosol. CONCLUSION: These results strongly confirm the pivotal and essential role of dUTPase in pyrimidine biosynthesis of P. falciparum intraerythrocytic stages
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