1,417 research outputs found
Topological Quantum Phase Transition in Synthetic Non-Abelian Gauge Potential
The method of synthetic gauge potentials opens up a new avenue for our
understanding and discovering novel quantum states of matter. We investigate
the topological quantum phase transition of Fermi gases trapped in a honeycomb
lattice in the presence of a synthetic non- Abelian gauge potential. We develop
a systematic fermionic effective field theory to describe a topological quantum
phase transition tuned by the non-Abelian gauge potential and ex- plore its
various important experimental consequences. Numerical calculations on lattice
scales are performed to compare with the results achieved by the fermionic
effective field theory. Several possible experimental detection methods of
topological quantum phase tran- sition are proposed. In contrast to condensed
matter experiments where only gauge invariant quantities can be measured, both
gauge invariant and non-gauge invariant quantities can be measured by
experimentally generating various non-Abelian gauges corresponding to the same
set of Wilson loops
Optimizing ET-based irrigation scheduling for wheat and maize with water constraints
© 2017 American Society of Agricultural and Biological Engineers. Deficit irrigation has been shown to increase crop water use efficiency (WUE) under certain conditions, even though the yield is slightly reduced. In this study, the Root Zone Water Quality Model (RZWQM) was first calibrated with measured data from a large weighing lysimeter from 1998 to 2003 at the Yucheng Experimental Station in the North China Plain for daily evapotranspiration (ET), soil water storage (0-120 cm), leaf area index (LAI), aboveground biomass, and grain yield. The calibrated model was then used to explore crop responses to ET-based irrigation management using weather data from 1958 to 2015 and identify the most suitable ET-based irrigation schedules for the area. Irrigation amount was determined by constraining irrigation to a percentage of potential crop ET (40%, 60%, 80%, and 100% ETc) at the various growth stages of wheat [planting to before winter dormancy (P-D), green up to booting (G-B), booting to flowering (B-F), and flowering to maturity (F-M)] and of maize [planting to silking (P-S) and silking to maturity (S-M)], subject to seasonal water availability limits of 100/50, 200/100, 300/150, and 400/200 mm and no water limit for wheat/maize seasons, respectively. In general, wheat was more responsive to irrigation than maize, while greater influence of weather variation was simulated on maize than on wheat. For wheat with seasonal water limits, the highest average WUE was simulated with the highest targeted ETc levels at both the G-B and B-F stages and lower targeted ETc levels at the P-D and F-M stages. However, the highest average grain yield was simulated with the highest targeted ETc levels at all four growth stages for no water limit and the 400 mm water limit, or at both the G-B and B-F stages for the 300 and 200 mm water limits. For maize, lower targeted ETc levels after silking did not significantly affect maize production due to the high season rainfall, but irrigation of 60% ETc before silking was recommended. These results could be used as guidelines for precision irrigation along with real-time weather information
Real-time counting of single electron tunneling through a T-shaped double quantum dot system
Real-time detection of single electron tunneling through a T-shaped double
quantum dot is simulated, based on a Monte Carlo scheme. The double dot is
embedded in a dissipative environment and the presence of electrons on the
double dot is detected with a nearby quantum point contact. We demonstrate
directly the bunching behavior in electron transport, which leads eventually to
a super-Poissonian noise. Particularly, in the context of full counting
statistics, we investigate the essential difference between the dephasing
mechanisms induced by the quantum point contact detection and the coupling to
the external phonon bath. A number of intriguing noise features associated with
various transport mechanisms are revealed.Comment: 8 pages, 5 figure
Mapping the unconventional orbital texture in topological crystalline insulators
The newly discovered topological crystalline insulators (TCIs) harbor a
complex band structure involving multiple Dirac cones. These materials are
potentially highly tunable by external electric field, temperature or strain
and could find future applications in field-effect transistors, photodetectors,
and nano-mechanical systems. Theoretically, it has been predicted that
different Dirac cones, offset in energy and momentum-space, might harbor vastly
different orbital character, a unique property which if experimentally
realized, would present an ideal platform for accomplishing new spintronic
devices. However, the orbital texture of the Dirac cones, which is of immense
importance in determining a variety of materials properties, still remains
elusive in TCIs. Here, we unveil the orbital texture in a prototypical TCI
PbSnSe. By using Fourier-transform (FT) scanning tunneling
spectroscopy (STS) we measure the interference patterns produced by the
scattering of surface state electrons. We discover that the intensity and
energy dependences of FTs show distinct characteristics, which can directly be
attributed to orbital effects. Our experiments reveal the complex band topology
involving two Lifshitz transitions and establish the orbital nature of the
Dirac bands in this new class of topological materials, which could provide a
different pathway towards future quantum applications
Cbl Enforces Vav1 Dependence and a Restricted Pathway of T Cell Development
Extensive studies of pre-TCR- and TCR-dependent signaling have led to characterization of a pathway deemed essential for efficient T cell development, and comprised of a cascade of sequential events involving phosphorylation of Lck and ZAP-70, followed by phosphorylation of LAT and SLP-76, and subsequent additional downstream events. Of interest, however, reports from our lab as well as others have indicated that the requirements for ZAP-70, LAT, and SLP-76 are partially reversed by inactivation of c-Cbl (Cbl), an E3 ubiquitin ligase that targets multiple molecules for ubiquitination and degradation. Analysis of signaling events in these Cbl knockout models, including the recently reported analysis of SLP-76 transgenes defective in interaction with Vav1, suggested that activation of Vav1 might be a critical event in alternative pathways of T cell development. To extend the analysis of signaling requirements for thymic development, we have therefore assessed the effect of Cbl inactivation on the T cell developmental defects that occur in Vav1-deficient mice. The defects in Vav1-deficient thymic development, including a marked defect in DN3-DN4 transition, were completely reversed by Cbl inactivation, accompanied by enhanced phosphorylation of PLC-γ1 and ERKs in response to pre-TCR/TCR cross-linking of Vav1-/-Cbl-/- DP thymocytes. Taken together, these results suggest a substantially modified paradigm for pre-TCR/TCR signaling and T cell development. The observed consensus pathways of T cell development, including requirements for ZAP-70, LAT, SLP-76, and Vav1, appear to reflect the restriction by Cbl of an otherwise much broader set of molecular pathways capable of mediating T cell development
Mass Size Distribution and Chemical Composition of the Surface Layer of Summer and Winter Airborne Particles in Zabrze, Poland
Mass size distributions of ambient aerosol were measured in Zabrze, a heavily industrialized city of Poland, during a summer and a winter season. The chemical analyses of the surface layer of PM10, PM2.5 and PM1 in this area were also performed by X-ray photoelectron spectroscopy (XPS). Results suggested that the influence of an atmospheric aerosol on the health condition of Zabrze residents can be distinctly stronger in winter than in summer because of both: higher concentration level of particulate matter (PM) and higher contribution of fine particles in winter season compared to summer. In Zabrze in June (summer) PM10 and PM2.5 reached about 20 and 14 μg/m3, respectively, while in December (winter) 57 and 51 μg/m3, respectively. The XPS analysis showed that elemental carbon is the major surface component of studied airborne particles representing about 78%–80% (atomic mass) of all detected elements
Convergent, Parallel and Correlated Evolution of Trophic Morphologies in the Subfamily Schizothoracinae from the Qinghai-Tibetan Plateau
Schizothoracine fishes distributed in the water system of the Qinghai-Tibetan plateau (QTP) and adjacent areas are characterized by being highly adaptive to the cold and hypoxic environment of the plateau, as well as by a high degree of diversity in trophic morphology due to resource polymorphisms. Although convergent and parallel evolution are prevalent in the organisms of the QTP, it remains unknown whether similar evolutionary patterns have occurred in the schizothoracine fishes. Here, we constructed for the first time a tentative molecular phylogeny of the schizothoracine fishes based on the complete sequences of the cytochrome b gene. We employed this molecular phylogenetic framework to examine the evolution of trophic morphologies. We used Pagel's maximum likelihood method to estimate the evolutionary associations of trophic morphologies and food resource use. Our results showed that the molecular and published morphological phylogenies of Schizothoracinae are partially incongruent with respect to some intergeneric relationships. The phylogenetic results revealed that four character states of five trophic morphologies and of food resource use evolved at least twice during the diversification of the subfamily. State transitions are the result of evolutionary patterns including either convergence or parallelism or both. Furthermore, our analyses indicate that some characters of trophic morphologies in the Schizothoracinae have undergone correlated evolution, which are somewhat correlated with different food resource uses. Collectively, our results reveal new examples of convergent and parallel evolution in the organisms of the QTP. The adaptation to different trophic niches through the modification of trophic morphologies and feeding behaviour as found in the schizothoracine fishes may account for the formation and maintenance of the high degree of diversity and radiations in fish communities endemic to QTP
Resequencing
[ES] La revolución que supone la secuenciación de próxima generación está permitiendo la resecuenciación del genoma completo (WGRS) de cientos o incluso miles de ejemplares de cultivos básicos y especies modelo. Con el lanzamiento de su genoma de referencia, progresivamente se están emprendiendo proyectos WGRS también para otras especies de plantas en una amplia variedad de estudios. En berenjena común (Solanum melongena L.), aunque se ha publicado un primer borrador de la secuencia del genoma de referencia, hasta el momento no se han realizado estudios de resecuenciación. En este capítulo presentamos los primeros resultados de la resecuenciación de ocho accesiones, siete de berenjena común y una del pariente silvestre S. incanum L., que corresponden a los progenitores de un cruce multiparental de generación avanzada (MAGIC) población que se encuentra actualmente en desarrollo utilizando la secuencia del genoma de la berenjena recién desarrollada que se presenta en el Cap. 7 de este libro. Se identificaron más de diez millones de polimorfismos entre las accesiones, el 90% de ellos en el S. incanum silvestre relacionado, lo que confirma la erosión genética de la berenjena común cultivada. Entre los progenitores de la población MAGIC, el patrón de distribución de polimorfismos comunes a lo largo de los cromosomas ha revelado posibles huellas de introgresión ancestral de cruces interespecíficos. El conjunto de polimorfismos se ha anotado extensamente y actualmente se está utilizando para análisis adicionales con el fin de genotipar eficientemente la población MAGIC en curso y diseccionar rasgos agronómicos y morfológicos importantes. La información proporcionada en este primer estudio de resecuenciación en berenjena será extremadamente útil para ayudar al fitomejoramiento a desarrollar nuevas variedades mejoradas y resistentes para enfrentar futuras amenazas y desafíos.[EN] The next-generation sequencing revolution is allowing the whole-genome resequencing (WGRS) of hundreds or even thousands of accessions for staple crops and model species. With the release of their reference genome, progressively also other plants, species are undertaking WGRS projects for a broad variety of studies. In common eggplant (Solanum melongena L.), although a first draft of the reference genome sequence has been published, no resequencing studies have been performed so far. In this chapter, we present the first results of the resequencing of eight accessions, seven of common eggplant and one of the wild relative S. incanum L., that correspond to the parents of a multi-parent advanced generation inter-cross (MAGIC) population that is currently under develop- ment using the newly developed eggplant genome sequence presented in Chap. 7 of this book. Over ten million polymorphisms were identified among the accessions, 90% of them in the wild related S. incanum, confirming the genetic erosion of the cultivated common eggplant. Among the MAGIC population parents, the common polymorphism distribu- tion pattern along the chromosomes has revealed possible footprints of ancestral intro- gression from interspecific crosses. The set of polymorphisms has been extensively anno- tated and currently is being used for further analyses in order to efficiently genotype the ongoing MAGIC population and to dissect important agronomic and morphological traits. The information provided in this first resequencing study in eggplant will be extremely helpful to assist plant breeding to develop new improved and resilient varieties to face future threats and challenges.This work has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No 677379 (G2P-SOL project: Linking genetic resources, genomes and phenotypes of Solanaceous crops) and from Spanish Ministerio de Economía, Industria y Competitividad and Fondo Europeo de Desarrollo Regional (grant AGL2015-64755-R from MINECO/FEDER).Prohens Tomás, J.; Vilanova Navarro, S.; Gramazio, P. (2019). Resequencing. En The Eggplant Genome. Springer. 81-89. http://hdl.handle.net/10251/181875S818
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