检索结果-南通市图书馆

CONSTANS alters the circadian clock in Arabidopsis thaliana

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Molecular Plant 2024年第8期17卷 1204-1220页

作者： Pedro de los Reyes Gloria Serrano-Bueno Francisco J.Romero-Campero He Gao jose M.Romero Federico valverde Plant Development Group-Institute for Plant Biochemistry and Photosynthesis Consejo Superior de Investigaciones CientificasUniversidad de SevillaSevilleSpain Department of Computer Science and Artificial Intelligence Universidad de SevillaSevilleSpain Department of Plant Developmental Biology Max Planck Institute for Plant Breeding ResearchCologneGermany Department of Plant Biochemistry and Molecular Biology Universidad de SevillaSevilleSpain

Plants are sessile organisms that have acquired highly plastic developmental strategies to adapt to the *** these processes,the floral transition is essential to ensure reproductive success and is finelyregulated by several internal andexternal genetic *** photoperiodic pathway,which controls plant response to day length,is one of the most important pathways controlling *** Arabidopsis photoperiodic flowering,CONSTANS(CO)is the central gene activating the expression of the florigen FLOWERING LOCUS T(FT)in the leaves at the end of a long *** circadian clock strongly regulates Co ***,to date,no evidence has been reported regarding a feedbackloop from the photoperiod pathway back to the circadian *** transcriptional networks,we have identified relevant network motifs regulating the interplay between the circadian clock and the photoperiod *** expression,chromatin immunoprecipitation experiments,and phenotypic analysis allowed us to elucidate the role of Co over the circadian *** with altered cO expression showed a different internal clock period,measured by daily leaf rhythmic *** showed that co upregulates the expression of key genes related to the circadian clock,such as CCA1,LHY,PRR5,and Gl,at the end of a long day by bindingto specific sites on their ***,a high numberof PRR5-repressed target genes are upregulated by CO,and this could explain the phase transition promoted by *** CO-PRR5 complex interacts with the bZiP transcriptionfactor HY5andhelps to localize the complex in the promoters of clock *** together,our results indicate that there may be a feedback loop in which co communicates back to the circadian clock,providing seasonal information to the circadian system.

关键词： CONSTANS circadian clock photoperiod

Acoustic streaming and Sun's meridional circulation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2016年第9期16卷 101-106页

作者： jose Manuel valverde Faculty of Physics University of Seville

A vast number of physical processes involving oscillations of a bounded viscous fluid are relevantly influenced by acoustic streaming. When this happens a steady circulation of fluid develops in a thin boundary adjacent to the interface. Some examples are refracted sound waves, a fluid inside a spherical cavity undergoing torsional oscillations or a pulsating liquid droplet. Steady streaming around circular interfaces consists of a hemispherically symmetric recirculation of fluid from the equatorial plane to the polar axes closely resembling the meridional circulation pattern observed in the Sun＇s convection zone that determines the solar cycle. In this paper, it is argued that the acoustic pulsations exhibited by the Sun would lead to acoustic streaming in the boundary of the convection zone. A simple estimation using a typical dominant frequency of 3 mHz and the observed surface oscillation amplitude yields a steady streaming velocity Us - 10 m s^-1, which is on the order of the meridional circulation velocity observed in the Sun＇s convection zone.

关键词： Sun general -- Sun helioseismology -- Sun granulation -- Sun oscillations -- Sun fun-damental parameters -- Sun activity

Magnetic field assisted fluidization:A modified Richardson-Zaki equation

在线全文

学校读者我要写书评

暂无评论

China Particuology 2007年第1期5卷 61-70页

作者： jose Manuel valverde Antonio Castellanos Faculty of Physics Universidad de Sevilla Avenida Reina Mercedes s/n 41012 Sevilla Spain

Magnetic particles can be uniformly fluidized by coupling the gas flow with an externally imposed magnetic field. Interparticle forces generated by the magnetic field cause aggregation of the particles in chain-like structures preferentially oriented along the magnetic field lines. In the present paper, we study the implications of the formation of these special types of aggregates on the empirical Richardson-Zaki （RZ） equation, originally proposed to describe the expansion of fluidized beds of non-aggregated particles. We have addressed two important issues, namely the flow regime, which is a function of the size of the aggregates, and the effect of shape and orientation of the chain-like aggregates with respect to gas flow on fluid drag. We propose a modified RZ equation （MRZE） in which the velocity scale, given by the terminal settling velocity of the individual aggregates, and the RZ exponent are predetermined as a function of the chain length. The chain length depends on the ratio of the magnetic energy to gravitational energy, and is estimated from the magnetic field intensity, and particle magnetization, size and density. Predictions of the MRZE are successfully compared with published results in the literature on the expansion of magnetic particles in the presence of externally applied magnetic fields.

关键词： Fluidization Geldart B Magnetic particles Aggregation Richardson-Zaki equation

亚热带森林植物的叶片和根系功能性状部分耦合但具有不同的群落性状分布格局

在线全文

学校读者我要写书评

暂无评论

Journal of Plant Ecology 2024年第1期17卷 94-110页

作者： Wenqi Luo Oscar J valverde-Barrantes Monique Weemstra James F Cahill Jr Zi Wang Dong He Yongfa Chen Chengjin Chu Youshi Wang State Key Laboratory of Biocontrol School of Life Sciences/School of EcologySun Yat-sen UniversityGuangzhou 510275China International Center for Tropical Botany Department of Biological SciencesFlorida International UniversityMiamiFL 33199USA Department of Biological Sciences University of AlbertaEdmontonABT6G 2E9Canada School of Ecology and the Environment Xinjiang UniversityUrumqi 830046China

植物的生态过程依赖于叶片和根系的功能运行,但少有研究同时关注这两类性状在群落中的分布格局(CTD)。本文测定了广东亚热带森林44种共生木本植物的16个叶片和根系性状,旨在检验类比的叶片和根系性状是否耦合,是否沿类似的功能性状谱变... 详细信息

植物的生态过程依赖于叶片和根系的功能运行,但少有研究同时关注这两类性状在群落中的分布格局(CTD)。本文测定了广东亚热带森林44种共生木本植物的16个叶片和根系性状,旨在检验类比的叶片和根系性状是否耦合,是否沿类似的功能性状谱变异,是否表现出类似的CTD,其CTD和群落加权平均性状值(CWM)是否沿环境梯度表现出类似的响应。研究结果表明,叶片和根系性状变异的第一轴均呈显出由资源获取向资源保守变异的经济学谱,但叶片变异的第二轴主要由叶片碳含量表征,而根系变异的第二轴主要由反映菌根协作程度的根系粗细表征。类比的叶片和根系化学性状整体正相关,但形态性状的耦合程度较低。在群落水平上,叶片和根系性状第一轴的CWM均随海拔升高而变得更保守,而第二轴的变化则不一致。随土壤磷含量的降低或钾含量的升高,根系变得更细和在养分性状上更保守,而叶片性状无显著变化。当整合多维性状轴时,叶片性状呈发散格局,且随海拔、土壤磷和钾含量的增加呈收敛趋势;而根系性状呈收敛格局,但沿上述环境梯度呈发散趋势。该研究强调,叶片和根系性状与环境互作的差异可能导致不同的性状分布格局;植物可通过多样的地上和地下功能设计应对环境异质性。

关键词：性状维度群落构建叶片性状根系性状植物经济谱群落性状结构亚热带森林

Probing the nature of the contact between fine particles by using ultrasound propagation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2011年第6期9卷 659-662页

作者： Antonio Castellanos Xiaoping Jia Carlos Soria-Hoyo jose Manuel valverde Faculty of Physics University of Seville Avda. Reina Mercedes s/n 41012 Seville Spain LPMDI Universite de Marne-la-Vallee CNRS UMR 8108 Champs sur Marne France

The propagation velocity （Vs） of an ultrasonic signal through a granular material depends on the type of interparticle contact. For noncohesive glass beads, a power law behavior Vs α σc1/6 for consolidation stresses applied （σc） above 1 MPa has been measured in previous work. This equation is compatible with Hertz＇s interaction law between elastic solids. In the present work, we have tested the propagation velocity of ultrasound signals through a sample of fine powder. The tensile strength and compactivity of the powder were previously measured by means of the Seville powder tester （SPT）, indicating plastic deformation of the surface asperities in contact for small to moderate consolidation stresses. However, the measurements of ultrasound propagation at high consolidations presented here are compatible with Hertz＇s law. This finding suggests that for high consolidation stresses, surface asperities are flattened, and it is therefore the elastic deformation of the bulk of the particles that determines the transmission of ultrasonic pulses.

关键词： JFine cohesive powder Ultrasound propagation Interparticle contact

Factors affecting the dominance hierarchy dynamics in a hummingbird assemblage

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2019年第3期65卷 261-268页

作者： Ubaldo MARQUEZ-LUNA Carlos Lara Pablo CORCUERA Pedro luis valverde Doctorado en Ciencias Biologicas y de la Salud Universidad Autonoma Metropolitana-lztapalapa Ciudad de Mexico Mexico Centro de Investigacion en Ciencia Biologicas Universidad Autonoma de Tlaxcala. Km 10.5 Autopista Tlaxcala-San Martin Texmelucan San Felipe Ixtacuixtla Tlaxcala Mexico Departamento de Biologia Universidad Autonoma Metropolitana-lztapalapa Ciudad de Mexico

Intra and in terspecific competiti on for n ectar play an imports nt role in hummingbird communities. Larger sized species usually exclude smaller species from the rich floral resources. However, it has been recently postulated that the competitive advantages of a large body size decline as the evolutionary distance between the contending species in creases. In this study, we analyzed dominance hierarchy dynamics in a hummingbird assemblage in central Mexico. By monitoring hummingbird territories established in three plant species through 1 year, we assessed the effects of energy within territories and the territory owners identity in the frequency of inter and intraspecific encounters. We also evaluated if these factors affect the dominance of larger species when they compete against smaller distantly related contenders. Our results show that their frequency of intraspecific encounters was related with the identity of the territory's owner. On the contrary, the frequency of interspecific encounters was related with both the territory and the identity of the territory's owner. We did not find a significant difference between the number of encounters dominated by larger and smaller species and their conte nders. However, the in crease in genetic dista nee between contenders was positively associated with a higher frequency of encounters dominated by small *** results showed that the ecological factors and evolutionary relationships among contenders play important roles in the dominance hierarchy dynamics.

关键词： agonistic behavior competition hummingbirds resource quality territoriality

Aminopeptidase A and dipeptidyl peptidase 4:a pathogenic duo in Alzheimer’s disease?

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2022年第10期17卷 2215-2217页

作者： Frédéric Checler Audrey valverde UniversitéCôte d’Azur INSERMCNRSIPMCteam labelled“Laboratory of Excellence(LABEX)DistAlz”ValbonneFrance

The etiology of Alzheimer’s disease is far from being completely *** approaches have helped in this matter and have greatly supported the view that theβ-amyloid precursor protein(βAPP)could be at the center of gravity of the ***,mutations responsible for autosomal dominant aggressive forms of Alzheimer’s disease(AD)are all harbored by eitherβAPP itself or by its cleaving enzyme presenilins 1/2 referred to asγ-*** was therefore convincing to note that fully independent gene products harboring AD-linked mutations,all concur to modulateβAPP proteolytic *** genetic clues combined with a bulk of anatomical observations and cellular manipulations pointed to the role of amyloid-β(Aβ),the main biochemical component of senile plaques that accumulate at late stages of ***,a series of clinical trials designed to either abolish Aβproduction or neutralize it once produced have consistently failed(Checler et al.,2021).

关键词： Alzheimer Aβ senile

Local Isoperimetric Inequalities for Sectors on Surfaces and Cones

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2007年第7期23卷 1317-1326页

作者： Fernando GIMNEZ Javier Orengo valverde Department de Matemdtica Aplicada University Politécnica de ValenciaCamino de Vera s/n46022SPAIN Department de Matemáticas University de Castilla la ManchaAvda.de Espaas/n02071AlbaceteSpain

On surfaces we give conditions under which the solution of a restricted local isoperimetric problem for sectors with small solid angle is the circular sector and we characterize these surfaces. Also we study this prob... 详细信息

关键词： isoperimetric cones solid angle

Use of silica nanopowder to accelerate CO_2 sorption by Ca(OH)_2

在线全文

学校读者我要写书评

暂无评论

Particuology 2013年第4期11卷 448-453页

作者： M.A.S.Quintanilla J.M.valverde Faculty of Physics University of SevilleAvenida Reina Mercedes s/n

Promising technologies have recently emerged to capture CO2 from postcombustion flue gas and to enhance the production of hydrogen from natural gas by steam-methane reforming, on the basis of sorp- tion of CO2 by Ca-based powders. The rate of CO2 sorption on Ca-based powders is limited by both carbonation kinetics and transport of CO2 to unreacted sorption sites. Ca-based powders may exhibit cohesive aggregation, thus hindering gas-solids contact efficiency. In our work, we tested the sorption rate of powder samples prepared by dry mixing of a cohesive Ca（OH）2 powder with a silica nanopowder used as additive. The silica nanopowder serves to improve the dispersibility of Ca（OH）2. Consequently, when a CO2 enriched gas and the modified sorbent are brought into contact, the rate of CO2 sorption is enhanced in the initial fast phase of interest for practical applications.

关键词： FluidizationFine powdersCO2 sorptionNanoparticles