51,188 research outputs found
Thinning of Organic Apple Production with Potassic Soap and Calcium Polysulfide at the North of Spain.
Asturias, in the North West coast of Spain, is a region with old tradition at cultivation of
apple and its transformation to cider. The production of apple is mainly done under
traditional uses and semi-extensive or semi-intensive system and with local cultivars.
Thinning strategy is little practiced and the biennial bearing cycle is one of the main
problems for the farmers. The production of apple under organic techniques in Asturias is
still limited but increasing. Since 2005, experiments have been conducted on several
cultivars (‘Raxao’, ‘Xuanina’ and ‘Gold-Rush’) to evaluate the effects of Potassic Soap
(with or without olive oil) and Calcium Polysulfide as thinning products. We present here
the first promising results of these experiments. With different concentrations of both
products we have increased the apple production of two cultivars for the period 2006-
2007. There were positive effects on the vegetative growth of the trees and on the quality
of apples. In the spring 2007 we initiated new experiments with other cultivars (‘Durona de
Tresali’, ‘Solarina’, ‘Raxao’, ‘Regona’) in order to confirm our results. The new experiments
also include the comparison of their effects with those of commonly used chemical
products and with those of manual thinning techniques
New understanding of the shape-memory response in thiol-epoxy click systems: towards controlling the recovery process
Our research group has recently found excellent shape-memory response in “thiol-epoxy” thermosets obtained with click-chemistry. In this study, we use their well-designed, homogeneous and tailorable network structures to investigate parameters for better control of the shape-recovery process. We present a new methodology to analyse the shape-recovery process, enabling easy and efficient comparison of shape-memory experiments on the programming conditions. Shape-memory experiments at different programming conditions have been carried out to that end. Additionally, the programming process has been extensively analysed in uniaxial tensile experiments at different shape-memory testing temperatures. The results showed that the shape-memory response for a specific operational design can be optimized by choosing the correct programming conditions and accurately designing the network structure. When programming at a high temperature (T » Tg), under high network mobility conditions, high shape-recovery ratios and homogeneous shape-recovery processes are obtained for the network structure and the programmed strain level (eD). However, considerably lower stress and strain levels can be achieved. Meanwhile, when programming at temperatures lower than Tg, considerably higher stress and strain levels are attained but under low network mobility conditions. The shape-recovery process heavily depends on both the network structure and eD. Network relaxation occurs during the loading stage, resulting in a noticeable decrease in the shape-recovery rate as eD increases. Moreover, at a certain level of strain, permanent and non-recoverable deformations may occur, impeding the completion and modifying the whole path of the shape-recovery process.Postprint (author's final draft
A novel low-voltage reconfigurable ΣΔ modulator for 4G wireless receivers
This paper presents a new adaptable cascade
ΣΔ
modulator architecture fo
r low-voltage multi-stan-
dard applications. It uses two reconfiguration strategies:
a programmable global resonation and a variable
loop-filter order. These techniques are properly com-
bined in a novel topology that allows to increase the effec-
tive resolution in a given bandwidth, whereas keeping
relaxed output swing requirements and high robustness
to mismatch and to non-linearities of the amplifiers.
Time-domain simulations incl
uding the main
circuit-level
non-idealities are shown to demonstrate the benefits of
the presented modulator when it is configured to cope
with the requirements of GSM, UMTS, WLAN and
Wi-Max.España, Ministerio de Educación y Ciencia TEC2007-67247-C02-01/MICEspaña, Ministerio de Innovación, Ciencia y Empresa, Junta de Andalucía TIC-253
Continuous-time cascaded ΣΔ modulators for VDSL: A comparative study
This paper describes new cascaded continuous-time ΣΔ modulators intended to cope with very high-rate digital subscriber line specifications, i.e 12-bit resolution within a 20-MHz signal bandwidth. These modulators have been synthesized using a new methodology that is based on the direct synthesis of the whole cascaded architecture in the continuous-time domain instead of using a discrete-to-continuous time transformation as has been done in previous approaches. This method allows to place the zeroes/poles of the loop-filter transfer function in an optimal way and to reduce the number of analog components, namely, transconductors and/or amplifiers, resistors, capacitors and digital-to-analog converters. This leads to more efficient topologies in terms of circuitry complexity, power consumption and robustness with respect to circuit non-idealities. A comparison study of the synthesized architectures is done considering their sensitivity to most critical circuit error mechanisms. Time-domain behavioral simulations are shown to validate the presented approach.Ministerio de Educación y Ciencia TEC2004-01752/MI
Gamow-Siegert functions and Darboux-deformed short range potentials
Darboux-deformations of short range one-dimensional potentials are
constructed by means of Gamow-Siegert functions (resonance states). Results
include both Hermitian and non-Hermitian short range potentials which are
exactly solvable. As illustration, the method is applied to square wells and
barriers for which the transmission coefficient is a superposition of
Fock-Breit-Wigner distributions. Resonance levels are calculated in the long
lifetime limit by means of analytical and numerical approaches. The new complex
potentials behave as an optical device which both refracts and absorbs light
waves.Comment: 20 pages, 15 figures, LaTeX fil
Local detection of enzymatic ion generation with polycrystalline silicon interdigitated electrodes and its application to biosensing
Chips containing polycrystalline silicon interdigitated electrodes are modified with the enzyme urease. The sensors are able to detect changes in the resitivity of the solution near their surface, where the enzymatic reaction generates charged species. The electrodes are also grafted with an antigen and queried with different amounts of urease labeled antibody. The response of the modified electrodes is proportional to the amount of enzyme attached to the surface by the biorecognition event, thus validating the assay for biosensing applications
Heparan sulfate proteoglycans undergo differential expression alterations in left sided colorectal cancer, depending on their metastatic character
Abstract Background Heparan sulfate proteoglycans (HSPGs) are complex molecules which play a role in the invasion and growth and metastatic properties of cancerous cells. In this work we analyze changes in the patterns of expression of HSPGs in left sided colorectal cancer (LSCRC), both metastatic and non-metastatic, and the results are also compared with those previously obtained for right sided tumors (RSCRCs). Methods Eighteen LSCRCs were studied using qPCR to analyze the expression of both the proteoglycan core proteins and the enzymes involved in heparan sulfate chain biosynthesis. Certain HSPGs also carry chondroitin sulfate chains and so we also studied the genes involved in its biosynthesis. The expression of certain genes that showed significant expression differences were also analysed using immunohistochemical techniques. Results Changes in proteoglycan core proteins were dependent on their location, and the main differences between metastatic and non-metastatic tumors affected cell-surface glypicans, while other molecules were quite similar. Glypicans were also responsible for the main differences between RS- and LS- malignances. Regarding the biosynthesis of heparan sulfate chains, differential alterations in transcription depending on the presence or not of metastasis affected genes involved in the modification of uronic acid (epimerization and 2-O sulfation), and some isoforms responsible for sulfation of glucosamine (NDST1, HS6ST1). Moreover, in RSCRCs differences were preferentially found in the expression of genes involved in C6 and C3 sulfation of glucosamine, but not in NDSTs or SULFs. Finally, synthesis of chondroitin sulfate showed some alterations, which affected various steps, including polimerization and the modification of chains, but the main variations dependent on the presence of metastases were epimerization and 6C sulfation; however, when compared with RSCRCs, the essential divergences affected polymerization of the chains and the 6C sulfation of the galactosamine residue. Conclusions We evidenced alterations in the expression of HSPGs, including the expression of cell surface core proteins, many glycosiltransferases and some enzymes that modify the GAG chains in LSCRCs, but this was dependent on the metastatic nature of the tumor. Some of these alterations are shared with RSCRCs, while others, focused on specific gene groups, are dependent on tumor localization
Two-layer particle filter for multiple target detection and tracking
This paper deals with the detection and tracking of an unknown number of targets using a Bayesian hierarchical model with target labels. To approximate the posterior probability density function, we develop a two-layer particle filter. One deals with track initiation, and the other with track maintenance. In addition, the parallel partition method is proposed to sample the states of the surviving targets
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