1,399 research outputs found
Epidermis foliar de trigo (Triticum aestivum L.) en relación al genotipo y al espaciamiento entre surcos
El objetivo de este trabajo fue estudiar el efecto del genotipo y del espaciamiento entre hileras sobre las características epidérmicas de la hoja bandera, en cultivares de trigo. Se sembraron cultivares comerciales, PROINTA Oasis (Oa) y Las Rosas INTA (Ri), y líneas experimentales (T7 y T24) a 2 distancias entre surcos (15 y 30 cm). Las variables consideradas fueron frecuencia estomática (FE), índice estomático (IE), frecuencia de pares sílico-suberosos (FSS), frecuencia de aguijones (FA), ancho (AE) y largo (LE) de estomas. LE fue la única variable en la que se evidenció interacción significativa distancia-cultivar. Con respecto algenotipo, se encontraron diferencias sicnificativas entre cultivares en FE, FA y AE, mientras que no afectó IE ni FSS. En relación a FA, Ri presentó mayor respuesta promedio que Oa y que T24 . Para AE, mostró O a una media significativamente mayor que la de los restantes, mientras que para FE, T7 tuvo una media significativamente menor que la de los cultivares comerciales . Coincidiendo con otros autores, se puede considerar la FE como un criterio a tener en cuenta en la selección de nuevos cultivares
Feasibility of Electrified Propulsion for Ultra-Efficient Commercial Aircraft Final Report
MIT, Aurora Flight Sciences, and USC have collaborated to assess the feasibility of electric, hybridelectric, and turbo-electric propulsion for ultra-efficient commercial transportation. The work has drawn on the team expertise in disciplines related to aircraft design, propulsion-airframe integration, electric machines and systems, engineering system design, and optimization. A parametric trade space analysis has been carried out to assess vehicle performance across a range of transport missions and propulsion architectures to establish how electrified propulsion systems scale. An optimization approach to vehicle conceptual design modeling was taken to enable rapid multidisciplinary design space exploration and sensitivity analysis. The results of the analysis indicate vehicle aero-propulsive integration benefits enabled by electrification are required to offset the increased weight and loss associated with the electric system and achieve enhanced performance; the report describes the conceptual configurations than can offer such enhancements. The main contribution of the present work is the definition of electric vehicle design attributes for potential efficiency improvements at different scales. Based on these results, key areas for future research are identified, and extensions to the trade space analysis suitable for higher fidelity electrified commercial aircraft design and analysis have been developed
A Detailed Investigation into Low-Level Feature Detection in Spectrogram Images
Being the first stage of analysis within an image, low-level feature detection is a crucial step in the image analysis process and, as such, deserves suitable attention. This paper presents a systematic investigation into low-level feature detection in spectrogram images. The result of which is the identification of frequency tracks. Analysis of the literature identifies different strategies for accomplishing low-level feature detection. Nevertheless, the advantages and disadvantages of each are not explicitly investigated. Three model-based detection strategies are outlined, each extracting an increasing amount of information from the spectrogram, and, through ROC analysis, it is shown that at increasing levels of extraction the detection rates increase. Nevertheless, further investigation suggests that model-based detection has a limitation—it is not computationally feasible to fully evaluate the model of even a simple sinusoidal track. Therefore, alternative approaches, such as dimensionality reduction, are investigated to reduce the complex search space. It is shown that, if carefully selected, these techniques can approach the detection rates of model-based strategies that perform the same level of information extraction. The implementations used to derive the results presented within this paper are available online from http://stdetect.googlecode.com
Effect of Lifestyle Intervention in the Concentration of Adipoquines and Branched Chain Amino Acids in Subjects with High Risk of Developing Type 2 Diabetes: Feel4Diabetes Study
Introduction: The global prevalence of type 2 diabetes (T2D) is increasing rapidly, especially in low- and middle-income countries and has a high number of associated comorbidities. Plasmatic concentrations of branched chain amino acids (BCAA) and retinol-binding protein 4 (RBP4) have been shown to be elevated in T2D subjects in cross-sectional studies. However, the effect of lifestyle community-based interventions on BCAA and RBP4 concentrations has not yet been analyzed.
Material and methods: The Feel4Diabetes study is a school and community-based intervention that identified 360 European families with a high risk of developing T2D according to the FINDRISC questionnaire. Families were randomized in control and intervention groups were followed-up from 2016 to 2018. In the Spanish families, the concentration of BCAA and RBP4 was determined in 266 subjects (115 control and 151 intervention group) that attended the three time-point assessments by colorimetric and ELISA reaction, respectively.
Results: Baseline BCAA levels showed positive correlations with the FINDRISC score and glucose impairment (baseline glucose, insulin, and glycated hemoglobin), body mass index, and body weight. The participants receiving the community-based intervention showed a significant decrease in glycated hemoglobin and BCAA levels compared to the control group (p = 0.011 and p < 0.001, respectively). However, baseline RBP4 did not show significant correlations with anthropometric and glycemic parameters, and no significant change was observed in anthropometric parameters and RBP4 concentrations throughout the follow-up.
Conclusion: A community-based intervention on lifestyle led to a significant reduction in BCAA levels regardless of weight loss. These findings suggest that this interventional approach could be promising in T2D prevention
Evaluation of Sedentary Behavior and Physical Activity Levels Using Different Accelerometry Protocols in Children from the GENOBOX Study
Background Physical activity (PA) has acquired a significant relevance due to the health benefits associated with its practice. Accelerometers are an effective tool to assess PA; however, the diversity of cut-off points used to define different PA intensities through accelerometry could interfere in the interpretation of the findings among studies. Objectives The present study aimed to examine the sedentary behavior (SB) and physical activity (PA) levels in children using six selected accelerometry protocols based on diverse cut-off points. Methods Clinical examination, anthropometric measurements, and PA evaluation by accelerometry were assessed in 543 selected children (10 +/- 2.4 years old) from the Spanish GENOBOX study. The ActiLife data scoring program was used to determine daily min spent in SB, and light, moderate, vigorous and moderate-vigorous PA using six validated accelerometry protocols differing in their cut-off points. Results Very different estimations for SB and PA intensity levels were found in children, independently of the non-wear-time algorithm selected, and considering puberty stages, age and body mass index. The time spent in daily SB varied from 471 to 663.7 min, PA ranged from 141 to 301.6 min, and the moderate-vigorous PA was reported between 20.7 and 180.2 min. Conclusion The choice of a particular accelerometry protocol considering these factors is important to evaluate SB or PA intensities to suit the characteristics of the sample researched. It seems necessary to establish future lines of research that include different analytical approaches to measure SB and PA by accelerometry based on standardized and validated methodology
Vertical transport and electroluminescence in InAs/GaSb/InAs structures: GaSb thickness and hydrostatic pressure studies
We have measured the current-voltage (I-V) of type II InAs/GaSb/InAs double
heterojunctions (DHETs) with 'GaAs like' interface bonding and GaSb thickness
between 0-1200 \AA. A negative differential resistance (NDR) is observed for
all DHETs with GaSb thickness 60 \AA below which a dramatic change in the
shape of the I-V and a marked hysteresis is observed. The temperature
dependence of the I-V is found to be very strong below this critical GaSb
thickness. The I-V characteristics of selected DHETs are also presented under
hydrostatic pressures up to 11 kbar. Finally, a mid infra-red
electroluminescence is observed at 1 bar with a threshold at the NDR valley
bias. The band profile calculations presented in the analysis are markedly
different to those given in the literature, and arise due to the positive
charge that it is argued will build up in the GaSb layer under bias. We
conclude that the dominant conduction mechanism in DHETs is most likely to
arise out of an inelastic electron-heavy-hole interaction similar to that
observed in single heterojunctions (SHETs) with 'GaAs like' interface bonding,
and not out of resonant electron-light-hole tunnelling as proposed by Yu et al.
A Zener tunnelling mechanism is shown to contribute to the background current
beyond NDR.Comment: 8 pages 12 fig
Spatial correlations in vote statistics: a diffusive field model for decision-making
We study the statistics of turnout rates and results of the French elections
since 1992. We find that the distribution of turnout rates across towns is
surprisingly stable over time. The spatial correlation of the turnout rates, or
of the fraction of winning votes, is found to decay logarithmically with the
distance between towns. Based on these empirical observations and on the
analogy with a two-dimensional random diffusion equation, we propose that
individual decisions can be rationalised in terms of an underlying "cultural"
field, that locally biases the decision of the population of a given region, on
top of an idiosyncratic, town-dependent field, with short range correlations.
Using symmetry considerations and a set of plausible assumptions, we suggest
that this cultural field obeys a random diffusion equation.Comment: 18 pages, 5 figures; added sociophysics references
Sharp Trace Hardy-Sobolev-Maz'ya Inequalities and the Fractional Laplacian
In this work we establish trace Hardy and trace Hardy-Sobolev-Maz'ya
inequalities with best Hardy constants, for domains satisfying suitable
geometric assumptions such as mean convexity or convexity. We then use them to
produce fractional Hardy-Sobolev-Maz'ya inequalities with best Hardy constants
for various fractional Laplacians. In the case where the domain is the half
space our results cover the full range of the exponent of the
fractional Laplacians. We answer in particular an open problem raised by Frank
and Seiringer \cite{FS}.Comment: 42 page
On Isotropic Turbulence in the Dark Fluid Universe
As first part of this work, experimental information about the decay of
isotropic turbulence in ordinary hydrodynamics, u^2(t) proportional to
t^{-6/5}, is used as input in FRW equations in order to investigate how an
initial fraction f of turbulent kinetic energy in the cosmic fluid influences
the cosmological development in the late, quintessence/phantom, universe. First
order perturbative theory to the first order in f is employed. It turns out
that both in the Hubble factor, and in the energy density, the influence from
the turbulence fades away at late times. The divergences in these quantities
near the Big Rip behave essentially as in a non-turbulent fluid. However, for
the scale factor, the turbulence modification turns out to diverge
logarithmically. As second part of our work, we consider the full FRW equation
in which the turbulent part of the dark energy is accounted for by a separate
term. It is demonstrated that turbulence occurrence may change the future
universe evolution due to dissipation of dark energy. For instance,
phantom-dominated universe becomes asymptotically a de Sitter one in the
future, thus avoiding the Big Rip singularity.Comment: 10 pages, no figures, significant revision. Matches published versio
- …