3,454 research outputs found
Eco-Physiological Screening of Different Tomato Genotypes in Response to High Temperatures: A Combined Field-to-Laboratory Approach
High temperatures represent a limitation for growth and development of many crop species. Several studies have demonstrated that the yield reduction of tomato under high temperatures and drought is mainly due to a photosynthetic decline. In this paper, a set of 15 tomato genotypes were screened for tolerance to elevated temperatures by cultivating plants under plastic walk-in tunnels. To assess the potential tolerance of tomato genotypes to high temperatures, measurements of chlorophyll fluorescence, pigments content and leaf functional traits have been carried out together with the evaluation of the final yields. Based on the greenhouse trials, a group of eight putative heat-sensitive and heat-tolerant tomato genotypes was selected for laboratory experiments aimed at investigating the effects of short-term high temperatures treatments in controlled conditions. The chlorophyll fluorescence induction kinetics were recorded on detached leaves treated for 60 min at 35 °C or at 45 °C. The last treatment significantly affected the photosystem II (PSII) photochemical efficiency (namely maximum PSII quantum efficiency, Fv/Fm, and quantum yield of PSII electron transport, ΦPSII) and the non-photochemical quenching (NPQ) in the majority of genotypes. The short-term heat shock treatments also led to significant differences in the shape of the slow Kautsky kinetics and its significant time points (chlorophyll fluorescence levels minimum O, peak P, semi-steady state S, maximum M, terminal steady state T) compared to the control, demonstrating heat shock-induced changes in PSII functionality. Genotypes potentially tolerant to high temperatures have been identified. Our findings support the idea that chlorophyll fluorescence parameters (i.e., ΦPSII or NPQ) and some leaf functional traits may be used as a tool to detect high temperatures-tolerant tomato cultivars
Diagnóstico molecular de huanglongbing dos citros, via qPCR, em mudas de valência sobre Swingle.
O HLB é, sem dúvidas, a grande ameaça da citricultura no país, por ser uma doença severa e destrutiva, com prejuízos no desenvolvimento da planta e na produção de frutos. Os agentes causais da doença são espécies da bactéria Candidatus Liberibacter spp., que se alojam em vasos do floema. Três espécies de Liberibacter estão associadas ao HLB dos citros: Ca. Liberibacter africanus, Ca. L. asiaticus e Ca. L. americanus, sendo as duas últimas de ocorrência no Brasil. A doença pode se propagar através de seu vetor, o psilídeo Diaphorina citri, e/ou por enxertia de tecidos infectados (Bové, 2006). O HLB não provoca a morte das plantas, mas, com o passar dos anos, elas se tornam debilitadas e improdutivas. Pomares inteiros podem ficar inviáveis economicamente dentro de sete a dez anos após o aparecimento da primeira planta sintomática se as medidas de controle não forem tomadas (Gottwald et al., 2007).O período de incubação do HLB depende de vários fatores, variando geralmente de seis a doze meses (Bové, 2006). Diante disso, a inspeção visual do pomar não representa o controle da doença, visto que plantas assintomáticas, porém infectadas, podem permanecer como fontes de inóculo para plantas ainda sadias. Como discutido por Bové (2006) e Gottwald et al. (2007), o conhecimento da proporção de plantas sintomáticas e assintomáticas é importante e deve ser utilizado na decisão da eliminação de pomares inteiros altamente infestados. Assim, a detecção de Ca. Liberibacter sp. precocemente é de extrema importância, pois minimiza, dentro do possível, o impacto financeiro aos citricultores com a erradicação das plantas.Hoje o método mais confiável para o diagnóstico do HLB é o PCR quantitativo em tempo real (qPCR), que amplifica e detecta o DNA bacteriano presente no tecido. O método visual é também utilizado, porém o diagnóstico é impreciso e pode levar a falsos negativos (plantas infectadas e ainda assintomáticas) ou falsos positivos, uma vez que os sintomas da doença podem ser facilmente confundidos com deficiência nutricional.pdf 186
Discovery of a directly imaged disk in scattered light around the Sco-Cen member Wray 15-788
As part of our on-going survey we have carried out high-contrast imaging with
VLT/SPHERE/IRDIS to obtain polarized and total intensity images of the young
(Myr old) K3IV star Wray 15-788 within the Lower Centaurus Crux
subgroup of Sco-Cen. For the total intensity images, we remove the stellar halo
by an approach based on reference star differential imaging in combination with
principal component analysis. Both total intensity and polarimetric data
resolve a disk around Wray 15-788. Modeling of the stellar spectral energy
distribution suggests that this is a protoplanetary disk at a transition stage.
We detect a bright, outer ring at a projected separation of 370mas
(56au), hints for inner substructures at 170mas (28au)
and a gap in between. Only within a position angle range of
, we are confident at 5 level to detect
actual scattered light flux from the outer ring of the disk; the remaining part
is indistinguishable from background noise. For the detected part of the outer
ring we determine a disk inclination of =216 and a
position angle of =7616. Furthermore, we find that
Wray 15-788 is part of a binary system with the A2V star HD 98363 at a
separation of 50'' (6900au). The detection of only half of the
outer ring might be due to shadowing by a misaligned inner disk. A potential
substellar companion can cause the misalignment of the inner structures and can
be responsible for clearing the detected gap from scattering material. We can
not, however, rule out the possibility of a non-detection due to our limited
signal to noise ratio, combined with brightness azimuthal asymmetry. From our
data, we can exclude companions more massive than 10 within the
gap at a separation of 230mas (35au).Comment: Accepted for publication in A&A (16 pages, 11 figures
Deformation effects in the Si+C and Si+Si reaction Search
The possible occurence of highly deformed configurations is investigated in
the Ca and Ni di-nuclear systems as formed in the
Si+C,Si reactions by using the properties of emitted light
charged particles. Inclusive as well as exclusive data of the heavy fragments
and their associated light charged particles have been collected by using the
{\sc ICARE} charged particle multidetector array. The data are analysed by
Monte Carlo CASCADE statistical-model calculations using a consistent set of
parameters with spin-dependent level densities. Significant deformation effects
at high spin are observed as well as an unexpected large Be cluster
emission of a binary nature.Comment: 3 pages latex, 2 eps figures, paper presented in "wokshop on physics
with multidetector array (pmda2000)Calcutta, India (to be published at
PRAMANA, journal of Physics, India
Element-Specific Magnetic Properties of Co2MnSi Thin Films
Co2MnSi thin films were grown on Al2O3 (a plane) and GaAs (001) substrates and on thin silicon nitride windows using pulsed laser deposition. Angle-dependent magneto-optic Kerr effect measurements reveal both a uniaxial and a fourfold magnetocrystalline anisotropy for films grown on GaAs (001). X-ray magnetic circular dichroism spectra were measured at the L2,3 edges of the thin films as a function of aluminum cap layer thickness, and transmission mode L2,3 x-ray absorption through a 1000-Å Co2MnSi film grown on a silicon nitride membrane were measured, indicating that deviations from metalliclike spectra are likely due oxidation or contamination. Element-specific moments for Co and Mn were calculated from the X-ray magnetic circular dichroism data of a nonoxidized film
Developement of real time diagnostics and feedback algorithms for JET in view of the next step
Real time control of many plasma parameters will be an essential aspect in
the development of reliable high performance operation of Next Step Tokamaks.
The main prerequisites for any feedback scheme are the precise real-time
determination of the quantities to be controlled, requiring top quality and
highly reliable diagnostics, and the availability of robust control algorithms.
A new set of real time diagnostics was recently implemented on JET to prove the
feasibility of determining, with high accuracy and time resolution, the most
important plasma quantities. With regard to feedback algorithms, new
model–based controllers were developed to allow a more robust control of
several plasma parameters. Both diagnostics and algorithms were successfully
used in several experiments, ranging from H-mode plasmas to configuration with
ITBs. Since elaboration of computationally heavy measurements is often
required, significant attention was devoted to non-algorithmic methods like
Digital or Cellular Neural/Nonlinear Networks. The real time hardware and
software adopted architectures are also described with particular attention to
their relevance to ITER.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004,
Nice (France
Access to administrative documents and to public sector information in Italy
Law No. 241 of 1990 on administrative procedure (Italian APA) established general rules on the right of access to administrative documents for the first time in the Italian legal system, which partly reproduced rules defined in sectorial legislations. From such very restrictive regime of access to administrative documents\u2014lately accompanied by a rather demagogical obligation imposed on public administrations to disclose a set of information in the context of the so-called open data policies\u2014Italy has recently moved forth to public access to data and documents held by public administrations
Handbook for Aboriginal Alcohol and Drug Work
The Handbook for Aboriginal Alcohol and Drug Work is a practical tool written for Aboriginal drug and alcohol workers, mental health workers and others working in this field. It offers a detailed look at alcohol and drug work from clinical, through to prevention, early intervention and harm reduction. This handbook is also likely to help people working to improve policy and those advocating for change. The idea for it came from workers all over Australia. They told us that they needed an easy to use handbook that can help them respond to the range of alcohol and drug issues they face every day. They also told us that such a book needs to take into account the complex challenges facing workers when helping clients, their families and, sometimes, whole communities
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