740 research outputs found

    Novel effects of strains in graphene and other two dimensional materials

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    The analysis of the electronic properties of strained or lattice deformed graphene combines ideas from classical condensed matter physics, soft matter, and geometrical aspects of quantum field theory (QFT) in curved spaces. Recent theoretical and experimental work shows the influence of strains in many properties of graphene not considered before, such as electronic transport, spin-orbit coupling, the formation of Moir\'e patterns, optics, ... There is also significant evidence of anharmonic effects, which can modify the structural properties of graphene. These phenomena are not restricted to graphene, and they are being intensively studied in other two dimensional materials, such as the metallic dichalcogenides. We review here recent developments related to the role of strains in the structural and electronic properties of graphene and other two dimensional compounds.Comment: 75 pages, 15 figures, review articl

    Design of Science Orbits About Planetary Satellites: Application to Europa

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76381/1/AIAA-19464-587.pd

    Effects of caffeine supplementation on physical performance and mood dimensions in elite and trained-recreational athletes.

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    Background: Caffeine supplementation (CAFF) has an established ergogenic effect on physical performance and the psychological response to exercise. However, few studies have compared the response to CAFF intake among athletes of different competition level. This study compares the acute effects of CAFF on anaerobic performance, mood and perceived effort in elite and moderately-trained recreational athletes. Methods: Participants for this randomized, controlled, crossover study were 8 elite athletes (in the senior boxing national team) and 10 trained-recreational athletes. Under two experimental conditions, CAFF supplementation (6 mg/kg) or placebo (PLAC), the athletes completed a Wingate test. Subjective exertion during the test was recorded as the rating of perceived exertion (RPE) both at the general level (RPEgeneral) and at the levels muscular (RPEmuscular) and cardiorespiratory (RPEcardio). Before the Wingate test, participants completed the questionnaires Profiles of Moods States (POMS) and Subjective Vitality Scale (SVS). Results: In response to CAFF intake, improvements were noted in Wpeak (11.22 ± 0.65 vs 10.70 ± 0.84; p = 0.003; η2 p =0.44), Wavg (8.75 ± 0.55 vs 8.41 0.46; p = 0.001; η2 p =0.53) and time taken to reach Wpeak (7.56 ± 1.58 vs 9.11 ± 1.53; p < 0.001; η2 p =0.57) both in the elite and trained-recreational athletes. However, only the elite athletes showed significant increases in tension (+ 325%), vigor (+ 31%) and SVS (+ 28%) scores after the intake of CAFF compared to levels recorded under the condition PLAC (p < 0.05). Similarly, levels of vigor after consuming CAFF were significantly higher in the elite than the trained-recreational athletes (+ 5.8%). Conclusions: CAFF supplementation improved anaerobic performance in both the elite and recreational athletes. However, the ergogenic effect of CAFF on several mood dimensions and subjective vitality was greater in the elite athletes.post-print700 K

    The search for gametic maturity markers in the gametogenic cycle of Crassostrea gigas (Thunberg, 1873)

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    One of the aims of bivalve culture is obtaining high quality broodstocks in hatcheries. Spawning feasibility depends on a suitable breeder's feeding, and can be artificially induced. Some external factors (environmental) and internal (neuroendocrinal) seem to contribute to gamete maturation. Crassostrea gigas (Thunberg, 1873) gametogenic cycle is characterised by long resting periods during which a high rate of degradation and cellular atresia has been observed. There are also remarkable differences between male and female protein profiles during gametogenic development. Our group has been searching for molecular indicators of the state of maturation, and the most suitable moment for spawning induction. One of our most promising results was the appearance of a membrane protein in females thought to be a signal receptor in oocyte maturation and spawning.El cultivo de bivalvos se ve limitado por la obtención de semilla de calidad en los criaderos. El éxito de las puestas depende de la alimentación adecuada de los reproductores, y pueden ser inducidas artificialmente mediante choque osmótico, térmico u otras técnicas. Algunos factores externos, como los ambientales, e internos, de carácter neuroendocrino, parecen contribuir a la maduración de los gametos. El ciclo gametogénico de Crassostrea gigas (Thunberg, 1873) se caracteriza por largos periodos de reposo gonadal, en los que se ha encontrado una tasa elevada de degradación y atresia celular. También se aprecian diferencias considerables entre hembras y machos en los perfiles proteínicos durante el desarrollo gametogénico. El presente trabajo está orientado a la búsqueda de marcadores del estado de madurez de los gametos como indicadores del momento más adecuado para inducir la puesta. Uno de los resultados obtenidos ha sido la visualización de una proteína de membrana en hembras, que se muestra en la fase de madurez de los ovocitos y en las puestas, que podría constituir uno de los macadores buscados.Instituto Español de Oceanografí

    Strain-induced Evolution of Electronic Band Structures in a Twisted Graphene Bilayer

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    Here we study the evolution of local electronic properties of a twisted graphene bilayer induced by a strain and a high curvature. The strain and curvature strongly affect the local band structures of the twisted graphene bilayer; the energy difference of the two low-energy van Hove singularities decreases with increasing the lattice deformations and the states condensed into well-defined pseudo-Landau levels, which mimic the quantization of massive Dirac fermions in a magnetic field of about 100 T, along a graphene wrinkle. The joint effect of strain and out-of-plane distortion in the graphene wrinkle also results in a valley polarization with a significant gap, i.e., the eight-fold degenerate Landau level at the charge neutrality point is splitted into two four-fold degenerate quartets polarized on each layer. These results suggest that strained graphene bilayer could be an ideal platform to realize the high-temperature zero-field quantum valley Hall effect.Comment: 4 figure

    Intravenous Busulfan and Melphalan as a Conditioning Regimen for Autologous Stem Cell Transplantation in Patients with Newly Diagnosed Multiple Myeloma: A Matched Comparison to a Melphalan-Only Approach

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    AbstractMelphalan 200 mg/m2 (MEL200) is the standard conditioning regimen administered to newly diagnosed patients with multiple myeloma (MM) undergoing autologous stem cell transplantation (ASCT). Few alternatives have been explored in order to improve the antimyeloma activity of this conditioning. We compare i.v. busulfan (BU) 9.6 mg/kg and MEL 140 mg/m2 (MEL140) versus MEL200 mg/m2 as a conditioning regimen before ASCT for newly diagnosed patients with MM. For this purpose, 51 patients receiving i.v. BU plus MEL were compared to 102 patients receiving MEL200 mg/m2 in a 1:2 matched control analysis. Matching criteria included age, clinical stage at diagnosis, and response to induction therapy. No differences in the overall and complete response (CR) rates were observed after ASCT between both groups. After a median follow-up of 63 and 50 months in control and BU plus MEL groups, progression-free survival (PFS) was 24 and 33 months, respectively (P = .10). Most frequent toxicities included mucositis and febrile neutropenia in both groups. No case of sinusoidal obstruction syndrome was observed. Transplant-related mortality was 4% and 2% in BU plus MEL and control groups, respectively. ASCT conditioned with i.v. BU plus MEL may be considered an effective and well-tolerated alternative to a MEL-only approach as a conditioning regimen for patients with MM who are candidates for ASCT. (Clinicaltrials.gov identifier: NCT00560053 and NCT00804947.

    Multi-band high resolution spectroscopy rules out the hot Jupiter BD+20 1790b - First data from the GIARPS Commissioning

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    Context. Stellar activity is currently challenging the detection of young planets via the radial velocity (RV) technique. Aims. We attempt to definitively discriminate the nature of the RV variations for the young active K5 star BD+20 1790, for which visible (VIS) RV measurements show divergent results on the existence of a substellar companion. Methods. We compare VIS data with high precision RVs in the near infrared (NIR) range by using the GIANO - B and IGRINS spectrographs. In addition, we present for the first time simultaneous VIS-NIR observations obtained with GIARPS (GIANO - B and HARPS - N) at Telescopio Nazionale Galileo (TNG). Orbital RVs are achromatic, so the RV amplitude does not change at different wavelengths, while stellar activity induces wavelength-dependent RV variations, which are significantly reduced in the NIR range with respect to the VIS. Results. The NIR radial velocity measurements from GIANO - B and IGRINS show an average amplitude of about one quarter with respect to previously published VIS data, as expected when the RV jitter is due to stellar activity. Coeval multi-band photometry surprisingly shows larger amplitudes in the NIR range, explainable with a mixture of cool and hot spots in the same active region. Conclusions. In this work, the claimed massive planet around BD+20 1790 is ruled out by our data. We exploited the crucial role of multi- wavelength spectroscopy when observing young active stars: thanks to facilities like GIARPS that provide simultaneous observations, this method can reach its maximum potential.Comment: 12 pages, 7 figure

    In vivo murine model of acquired resistance in myeloma reveals differential mechanisms for lenalidomide and pomalidomide in combination with dexamethasone

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    The development of resistance to therapy is unavoidable in the history of multiple myeloma patients. Therefore, the study of its characteristics and mechanisms is critical in the search for novel therapeutic approaches to overcome it. This effort is hampered by the absence of appropriate preclinical models, especially those mimicking acquired resistance. Here we present an in vivo model of acquired resistance based on the continuous treatment of mice bearing subcutaneous MM1S plasmacytomas. Xenografts acquired resistance to two generations of immunomodulatory drugs (IMiDs; lenalidomide and pomalidomide) in combination with dexamethasone, that was reversible after a wash-out period. Furthermore, lenalidomide-dexamethasone (LD) or pomalidomide-dexamethasone (PD) did not display cross-resistance, which could be due to the differential requirements of the key target Cereblon and its substrates Aiolos and Ikaros observed in cells resistant to each combination. Differential gene expression profiles of LD and PD could also explain the absence of cross-resistance. Onset of resistance to both combinations was accompanied by upregulation of the mitogen-activated protein kinaseextracellular signal-regulated kinase (ERK) kinase (MEK)ERK pathway and addition of selumetinib, a small-molecule MEK inhibitor, could resensitize resistant cells. Our results provide insights into the mechanisms of acquired resistance to LD and PD combinations and offer possible therapeutic approaches to addressing IMiD resistance in the clinic.Peer Reviewe
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