2,350 research outputs found

    Holographic kinetic k-essence model

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    We consider a connection between the holographic dark energy density and the kinetic k-essence energy density in a flat FRW universe. With the choice c1c\geq1, the holographic dark energy can be described by a kinetic k-essence scalar field in a certain way. In this paper we show this kinetic k-essential description of the holographic dark energy with c1c\geq1 and reconstruct the kinetic k-essence function F(X).Comment: 6 pages, 4 figures, revised version, accepted for publication in Phys.Lett.

    The influence of sensor placement on in-situ ultrasound wave velocity measurement.

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    Ultrasound wave velocity was measured in 30 pieces of Spanish Scots pine (Pinus sylvestris L.), 90 x 140 mm in cross-section and 4 m long. Five different sensor placement arrangements were used: end to end (V0), face to opposite face, edge to opposite edge, face to same face and edge to same edge. The pieces were successively shortened to 3, 2 and 1 m, in order to obtain these velocities and their ratios to reference value V0 for different lengths and angles with respect to the piece axis for the crossed measurements. The velocity obtained in crossed measurements is lower than V0. A correction coefficient for crossed velocities is proposed, depending on the angle, to adjust them to the V0 benchmark. The velocities measured on a surface, are also lower than V0, and their ratio with respect to V0 is close to 0.97 for distances equal to or greater than 18 times the depth of the beam

    Nanofilms of adsorbed thymol formed on titanium surfaces for biomedical applications. Antimicrobial activity and biocompatibility

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    Titanium (Ti) and its alloys are widely used in the construction of permanent orthopedic and cardiovascular implants. However, one of the most frequent causes of failures are bacterial infections by Staphylococcus aureus. This is aggravated by the abusive use of antibiotics that generate microbial resistance to conventional therapies. As a consequence, new antimicrobial nanotechnologies (AMN) emerge as promising alternatives to prevent prosthetic infections. The aim of this work was to evaluate the antimicrobial effect of an innovative AMN: thymol (TOH, phenolic phytocompound) nanofilms adsorbed on Ti (NPTOH-Ti) against S. aureus. The biocompatibility was also determined using preosteoblast cells (MC3T3-E1). To that end, 1 cm diameter grade 2 Ti discs were used and TOH was adsorbed onto their surface by 2 h immersion in 0.1 M TOH acid solution. NPTOH-Ti was detected by infrared spectroscopy (FTIR-ATR). The antibiofilm activity of NPTOH-Ti and Ti (control) was determined by immersing the metal discs in a suspension of S. aureus (108 bacteria/ml) for 3 h. Subsequently, the number of bacteria adhered on the discs was caunted after sonication by colony forming unit (CFU). In addition, Live/Dead (Invitrogen) staining was used to determine if the adhered bacteria were alive or dead. Finally, biocompatibility of NPTOH-Ti and Ti was assessed by staining the preosteoblast cells with acridine orange. The results showed that NPTOH-Ti has effective anti-biofilm properties. On the one hand, viable bacteria were not observed by the plating count method and Live/Dead staining exhibited only dead (red) bacteria on the surface. On the other hand, control Ti revealed 4 ± 0.5 x105 adhered bacteria that were mostly (95 %) alive (green). In addition, NPTOH-Ti and Ti showed similar cell adhesion and growth (107 ± 12 and 100 ± 16 % respectively; p>0.05). It was concluded that NPTOH-Ti are biocompatible and have anti-biofilm properties which make them promising to prevent prosthetic infections.Fil: Gonzalez, Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Miñan, Alejandro Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Grillo, Claudia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Schilardi, Patricia Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Fernandez Lorenzo, Monica Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaLXIV Reunión Anual de la Sociedad Argentina de Investigación Clínica; LI Reunión Anual de la Asociación Argentina de Farmacología Experimental; XXI Reunión Anual de la Sociedad Argentina de Biología; XXXI Reunión Anual de la Sociedad Argentina de Protozoología; IX Reunión Anual de la Asociación Argentina de Nanomedicinas y VI Reunión Científica Regional de la Asociación Argentina de Ciencia y Tecnología de Animales de LaboratorioArgentinaSociedad Argentina de Investigación ClínicaAsociación Argentina de Farmacología ExperimentalSociedad Argentina de BiologíaAsociación Argentina de Ciencia y Tecnología de Animales de LaboratorioSociedad Argentina de ProtozoologíaThe Histochemical Societ

    Tasa de sudoración y factores ambientales en regatistas juveniles de clase Láser

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    Summary Introduction: Recent studies have reported differences in sweat rate (SR) in laser class (LC) sailors under extreme environ-mental conditions (EC). This study aimed to determine a ‘standard-like’ SR in junior Laser 4.7 sailors under ‘not-extreme’ weather conditions to achieve an adequate fluid replacement rate for training and racing sessions. Additionally, we analysed the hypothetical relationship between SR and certain environmental factors, not just considering them as independent variables, but also including them as a whole factor, usually known as ‘windchill’ (WCh).Material and method: Nine male elite junior Laser 4.7 class athletes were included in this descriptive study. They were mo-nitored during the entire year of training and racing sessions, including national and international championships. Body mass changes as well as their food and fluid intake were measured for each sailor before and after sailing to estimate SR, absolute body mass change, and percentage body mass variation for all the sessions. Athletes were asked to maintain “ab libitum” fluid and food intake during the study. Environmental temperature, wind speed, and relative humidity were measured.Results: Significant differences (p = 0.012) were observed between training and racing sessions with respect to SR, 0.18 (± 0.14) L.h−1vs. 0.23 (± 0.12 L.h−1). Environmental temperature and WCh during racing showed an inverse relationship with SR.Discussion: This result suggests that increased fluid and food intake are required under cold weather conditions to maintain the ‘target’ weight during the competitions and improve performance.Resumen Introducción: Recientemente, algunos estudios han reportado diferencias en la tasa de sudoración (SR) en regatistas de clase láser (LC) bajo condiciones ambientales (EC) extremas. Este estudio pretende determinar una especie de “SR standard” en regatistas juveniles de Láser 4.7 bajo condiciones “no extremas”, con el objetivo de alcanzar una adecuada reposición de líquidos tanto para entrenamientos como en competición. Adicionalmente, se ha analizado una hipotética relación entre SR y los factores ambientales, considerándolos no únicamente como variables independientes, sino también como una variable compleja, conocida habitualmente como “sensación térmica” (WCh).Material y método: Nueve regatistas juveniles de Láser 4.7 han participado en este estudio descriptivo y prospectivo. Todos ellos han sido monitorizados durante todo un año de sesiones de entrenamiento y competición, incluyendo regatas nacio-nales como internacionales. Los cambios en la masa corporal, así como la ingesta de líquidos y sólidos han sido registrados de forma individual para cada regatista, antes y después de cada sesión para estimar la SR, los cambios totales en la masa corporal, así como las variaciones en el porcentaje de masa corporal. Se instó a los regatistas a ingerir comida y bebida “ab libidtum” a lo largo del estudio. La temperatura ambiental, la intensidad de viento y la humedad relativa fueron registradas.Resultados: Se observaron diferencias significativas (p = 0,012) para la SR entre los entrenos y las competiciones 0,18 (± 0,14) L.h−1vs. 0,23 (± 0,12 L.h−1). La temperatura ambiental y la WCh durante las competiciones mostraron además una relacióninversa con la SR.Discusión: Estos resultados sugieren que una mayor ingesta de líquidos y sólidos bajo condiciones de “frío ambiental” es necesaria para mantener el peso ideal, mejorando así el rendimiento durante la competición

    The physics potential of a reactor neutrino experiment with Skipper CCDs: Measuring the weak mixing angle

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    We analyze in detail the physics potential of an experiment like the one recently proposed by the vIOLETA collaboration: a kilogram-scale Skipper CCD detector deployed 12 meters away from a commercial nuclear reactor core. This experiment would be able to detect coherent elastic neutrino nucleus scattering from reactor neutrinos, capitalizing on the exceptionally low ionization energy threshold of Skipper CCDs. To estimate the physics reach, we elect the measurement of the weak mixing angle as a case study. We choose a realistic benchmark experimental setup and perform variations on this benchmark to understand the role of quenching factor and its systematic uncertainties,background rate and spectral shape, total exposure, and reactor antineutrino flux uncertainty. We take full advantage of the reactor flux measurement of the Daya Bay collaboration to perform a data driven analysis which is, up to a certain extent, independent of the theoretical uncertainties on the reactor antineutrino flux. We show that, under reasonable assumptions, this experimental setup may provide a competitive measurement of the weak mixing angle at few MeV scale with neutrino-nucleus scattering.Comment: 11 pages, 6 figure

    Kuruma: The Vehicle Automatic Data Capture for Urban Computing Collaborative Systems

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    Smartphones can provide coverage in large areas all around the world and with the availability of powerful operating systems they can become solid sensing infrastructures. In fact, static sensors are hard to deploy and maintain while modern mobile devices include many sensors that can be used to sense and benefit from collaborative communities. This project tries to improve urban computing by developing a framework able to create monitoring applications for mobile devices, focusing on obtaining the highest degree of interoperability between sensors. A prototype application has been developed to demonstrate the feasibility of creating multidisciplinary applications with several different approaches. The application developed consists of a Road Roughness Information System that measures smoothness and detects irregularities on the road

    Biomasa ramoneable procedente de resalveos sobre tallares envejecidos de encina

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    Los tallares envejecidos de encina ocupan una gran superficie en España, y presentan graves problemas selvícolas, ecológicos y económicos cuya solución podría venir de la aplicación de resalveos de conversión. Dicho tratamiento provoca inevitablemente un rebrote que debe ser controlado, siendo el ganado silvestre o doméstico la principal herramienta para ello. En este trabajo se presentan los resultados obtenidos durante los tres años siguientes tras la aplicación de claras de distinto peso en un tallar envejecido de Guadalajara, en relación con la producción de brotes de suelo. A modo de ejemplo, para un 50% de área basimétrica extraída se producen los siguientes kg de materia seca/ha como media: 132,2 el primer año; 265,1 el segundo año; 437,9 el tercer año. También se ofrecen, para los dos primeros años tras las claras, valores relativos al porcentaje de peso seco de hojas sobre el peso seco total de brotes de suelo: 53,3 % y 60,6 %, respectivamente

    <i>orsai</i>, the Drosophila homolog of human ETFRF1, links lipid catabolism to growth control

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    BACKGROUND: Lipid homeostasis is an evolutionarily conserved process that is crucial for energy production, storage and consumption. Drosophila larvae feed continuously to achieve the roughly 200-fold increase in size and accumulate sufficient reserves to provide all energy and nutrients necessary for the development of the adult fly. The mechanisms controlling this metabolic program are poorly understood. RESULTS: Herein we identified a highly conserved gene, orsai (osi), as a key player in lipid metabolism in Drosophila. Lack of osi function in the larval fat body, the regulatory hub of lipid homeostasis, reduces lipid reserves and energy output, evidenced by decreased ATP production and increased ROS levels. Metabolic defects due to reduced Orsai (Osi) in time trigger defective food-seeking behavior and lethality. Further, we demonstrate that downregulation of Lipase 3, a fat body-specific lipase involved in lipid catabolism in response to starvation, rescues the reduced lipid droplet size associated with defective orsai. Finally, we show that osi-related phenotypes are rescued through the expression of its human ortholog ETFRF1/LYRm5, known to modulate the entry of β-oxidation products into the electron transport chain; moreover, knocking down electron transport flavoproteins EtfQ0 and walrus/ETFA rescues osi-related phenotypes, further supporting this mode of action. CONCLUSIONS: These findings suggest that Osi may act in concert with the ETF complex to coordinate lipid homeostasis in the fat body in response to stage-specific demands, supporting cellular functions that in turn result in an adaptive behavioral response. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12915-022-01417-w

    Glioblastoma on a microfluidic chip: Generating pseudopalisades and enhancing aggressiveness through blood vessel obstruction events

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    Background: Glioblastoma (GBM) is one of the most lethal tumor types. Hypercellular regions, named pseudo- palisades, are characteristic in these tumors and have been hypothesized to be waves of migrating glioblastoma cells.These “waves” of cells are thought to be induced by oxygen and nutrient depletion caused by tumor-induced blood vessel occlusion. Although the universal presence of these structures in GBM tumors suggests that they may play an instrumental role in GBM’s spread and invasion, the recreation of these structures in vitro has remained challenging. Methods: Here we present a new microfluidic model of GBM that mimics the dynamics of pseudopalisade forma- tion.To do this, we embedded U-251 MG cells within a collagen hydrogel in a custom-designed microfluidic device. By controlling the medium flow through lateral microchannels, we can mimic and control blood-vessel obstruction events associated with this disease. Results: Through the use of this new system, we show that nutrient and oxygen starvation triggers a strong migratory process leading to pseudopalisade generation in vitro.These results validate the hypothesis of pseudo- palisade formation and show an excellent agreement with a systems-biology model based on a hypoxia-driven phenomenon. Conclusions: This paper shows the potential of microfluidic devices as advanced artificial systems capable of mod- eling in vivo nutrient and oxygen gradients during tumor evolution

    Assessment of platelet REACtivity after transcatheter aortic valve replacement

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    OBJECTIVES: The REAC-TAVI (Assessment of platelet REACtivity after Transcatheter Aortic Valve Implantation) trial enrolled patients with aortic stenosis (AS) undergoing transcatheter aortic valve replacement (TAVR) pre-treated with aspirin + clopidogrel, aimed to compare the efficacy of clopidogrel and ticagrelor in suppressing high platelet reactivity (HPR) after TAVI. BACKGROUND: Current recommendations support short-term use of aspirin + clopidogrel for patients with severe AS undergoing TAVR despite the lack of compelling evidence. METHODS: This was a prospective, randomized, multicenter investigation. Platelet reactivity was measured at 6 different time points with the VerifyNow assay (Accriva Diagnostics, San Diego, California). HPR was defined as (P2Y12 reaction units (PRU) ≥208. Patients with HPR before TAVR were randomized to either aspirin + ticagrelor or aspirin + clopidogrel for 3 months. Patients without HPR continued with aspirin + clopidogrel (registry cohort). The primary endpoint was non-HPR status (PRU <208) in ≥70% of patients treated with ticagrelor at 90 days post-TAVR. RESULTS: A total of 68 patients were included. Of these, 48 (71%) had HPR (PRU 273 ± 09) and were randomized to aspirin + ticagrelor (n = 24, PRU 277 ± 08) or continued with aspirin + clopidogrel (n = 24, PRU 269 ± 49). The remaining 20 patients (29%) without HPR (PRU 133 ± 12) were included in the registry. Overall, platelet reactivity across all the study time points after TAVR was lower in patients randomized to ticagrelor compared with those treated with clopidogrel, including those enrolled in the registry (p < 0.001). The primary endpoint was achieved in 100% of patients with ticagrelor compared with 21% with clopidogrel (p < 0.001). Interestingly, 33% of clopidogrel responder patients at baseline developed HPR status during the first month after TAVR. CONCLUSIONS: HPR to clopidogrel is present in a considerable number of patients with AS undergoing TAVR. Ticagrelor achieves a better and faster effect, providing sustained suppression of HPR to these patients. (Platelet Reactivity After TAVI: A Multicenter Pilot Study [REAC-TAVI]; NCT02224066)
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