In support of academic freedom     

Executive Committee of the International Human Rights Network of Academies  Scholarly Societies  Aluwihare A  Cohen-Tannoudji C  Daar AS  Jacob F  Koiller B  Nicolaisen I  Polanyi J  Selih A  van Dijk P  Vesentini E  Wiesel T  Corillon C 《Science (New York, N.Y.)》2007,316(5833):1840

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Drug delivery systems: entering the mainstream   总被引：2，自引：0，他引：2  

Allen TM  Cullis PR 《Science (New York, N.Y.)》2004,303(5665):1818-1822

Drug delivery systems (DDS) such as lipid- or polymer-based nanoparticles can be designed to improve the pharmacological and therapeutic properties of drugs administered parenterally. Many of the early problems that hindered the clinical applications of particulate DDS have been overcome, with several DDS formulations of anticancer and antifungal drugs now approved for clinical use. Furthermore, there is considerable interest in exploiting the advantages of DDS for in vivo delivery of new drugs derived from proteomics or genomics research and for their use in ligand-targeted therapeutics.  相似文献   

Assessment of orchard sprayers using laboratory experiments and computational fluid dynamics modelling     

Donald Dekeyser  Ashenafi T. Duga  Pieter Verboven  Ayenew Melese Endalew  Nico Hendrickx  David Nuyttens 《Biosystems Engineering》2013,114(2):157-169

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Branchial calcium uptake: possible mechanisms of control by stanniocalcin     

Pieter M. Verbost  Gert Flik  James C. Fenwick  Anna-Maria Greco  Peter K. T. Pang  Sjoerd E. Wendelaar Bonga 《Fish physiology and biochemistry》1993,11(1-6):205-215

The branchial Ca²⁺ uptake by teleost fish is under inhibitory control by the hormone stanniocalcin (STC) which is generated by the corpuscles of Stannius (CS). Removal of the CS in North American eel, Anguilla rostrata LeSueur, induced a rapid rise in blood calcium levels. Branchial Ca²⁺ influx following the extirpation of the CS (stanniectomy, STX) increased during the first four days and stayed elevated thereafter (in agreement with previous studies). The transepithelial potential (TEP) across the gills did not change after STX and this means that the electrochemical gradient for Ca²⁺ is less favourable for passive influx of Ca²⁺ in STX eel. Therefore, the Ca²⁺ influx in STX eels is a transcellular flux, with Ca²⁺ crossing the apical and basolateral membrane barrier. The kinetics of ATP-driven Ca²⁺-transport across basolateral plasma membranes from eel gills did not change after STX. Thus, the increased Ca²⁺-influx after STX is not correlated with changes in ATP-dependent Ca²⁺-extrusion across the basolateral membrane, suggesting a regulation at the apical membrane. Moreover, STC did not affect ATP-driven Ca²⁺-transport in isolated basolateral membranes (in vitro). STC (0.1 nM) reduced cAMP levels in dispersed eel gill cells. It had no significant effect on the IP₃ levels in these cells. We postulate that STC controls the permeability to Ca²⁺ of the apical membranes of the Ca²⁺ transporting cells of fish gills by controlling second messenger operated Ca²⁺ channels in the apical membrane.

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Résumé L'entrée de calcium au niveau des branchies est sous le controle inhibiteur de la stanniocalcine (STC) qui est synthétisée au niveau des corpuscules de Stannius (CS). L'ablation des CS chez l'anguille d'Amérique du Nord, Anguilla rostrata LeSueur, induit une augmentation rapide des niveaux de calcium dans le sang. Le flux entrant branchial de calcium consécutif à l'ablation des CS (stanniectomie, STX) augmente pendant les 4 premiers jours et reste élevé au-delà (en accord avec des études antérieures). Le potentiel transépithélial (TEP) à travers les branchies ne change pas après STX, ceci indiquant que le gradient électrochimique du Ca²⁺ est moins favorable pour le flux entrant passif du Ca²⁺ chez l'anguille STX. En conséquence, le flux entrant de Ca²⁺ chez l'anguille STX est un flux transcellulaire, avec le Ca²⁺ traversant la barrière membranaire apicale et basolatérale. La cinétique du transport de Ca²⁺ conduit par l'ATP à travers les membranes plasmatiques basolatérales de branches d'anguille n'est pas modifiée après STX. Ainsi, l'augmentation du flux entrant de Ca²⁺ après STX n'est pas corrlée avec des modifications de l'excrétion de Ca²⁺ conduit par l'ATP à travers la membrane basolatérale, suggérant donc une régulation au niveau de la membrane apicale. De plus, la STC ne modifie pas le transport de Ca²⁺ conduit par l'ATP dans des membranes basolatérales isolées (in vitro). La STC (0.1 nM) réduit les niveaux d'AMPc dans des cellules dispersées de branchies d'anguille. Cette hormone n'a pas d'effet significatif sur les niveaux d'IP₃ dans ces cellules. Nous suggérons que la STC régule la perméabilité au Ca²⁺ des membranes apicales des cellules branchiales transporteuses de Ca²⁺ en controlant un second messager agissant sur les canaux calciques de la membrane apicale.

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Survival and growth of elvers (Anguilla anguilla L.) reared on an expanded granulated diet     

P. Kastelein 《Aquaculture (Amsterdam, Netherlands)》1983,30(1-4):155-172

The suitability of a dry commercial expanded diet for the early rearing of newly-caught glass eels without weaning was investigated.

During a 104-day period, suitable feed particle sizes were determined for various sizes of fish, and growth and survival monitored. All mortalities, which totalled 28% of the initial population, occurred during the early stages of the experiment, suggesting that they were fish which either did not accept, or were unable to utilise, the diet given. No cannibalism was seen at any time. Overall growth rate and food conversion averaged 2.03% of bodyweight/day and 2.1 respectively. Selected, faster growing fish (35% of the stock) showed an average growth rate of 3.41%/day and a food conversion of 1.47.

The differences between the results obtained with the diet used and previously published data are discussed.  相似文献   

A template-free machine vision-based crop row detection algorithm     

Rabab  Saba  Badenhorst  Pieter  Chen  Yi-Ping Phoebe  Daetwyler  Hans D. 《Precision Agriculture》2021,22(1):124-153

Precision Agriculture - Due to the increase in the use of precision agriculture, field trials have increased in size to allow for genomic selection tool development by linking quantitative...  相似文献   

Exploring the potential of intersectoral partnerships to improve the position of farmers in global agrifood chains: findings from the coffee sector in Peru     

Verena Bitzer  Pieter Glasbergen  Bas Arts 《Agriculture and Human Values》2013,30(1):5-20

Despite their recent proliferation in global agricultural commodity chains, little is known about the potential of intersectoral partnerships to improve the position of smallholder farmers and their organizations. This article explores the potential of partnerships by developing a conceptual approach based on the sustainable livelihoods and linking farmers to market perspectives, which is applied in an exploratory study to six partnerships in the coffee sector in Peru. It is concluded that partnerships stimulate the application of standards to receive market access and therefore emphasize human capital development of farmers to facilitate certification. By transferring knowledge to farmers, partnerships present a new source of technological change, which, in combination with certification, holds potential for improved environmental management and price premiums for producers. However, the emphasis on certification results in a comparatively narrow target group of farmers and is associated with high financial burdens for producer organizations. At the same time, other assets of producer organizations are often not strengthened sufficiently for them to operate successfully without further external support. This suggests that preparing producers for certification is prioritized over empowering organizations toward self-dependence.  相似文献   

Acoustic,mechanical and microstructural properties of extruded crisp bread   总被引：1，自引：0，他引：1  

Ewa Gondek  Ewa Jakubczyk  Els Herremans  Bert Verlinden  Maarten Hertog  Thomas Vandendriessche  Pieter Verboven  Aleksandra Antoniuk  Evi Bongaers  Pascal Estrade  Bart M. Nicolaï 《Journal of Cereal Science》2013

The aim of this work was to describe the texture and structure of crisp bread obtained with different extrusion parameters. The texture of different crisp bread samples was evaluated using a combination of acoustic and mechanical tests. The advantage of this measurement setup is the feasibility of simultaneous registering of the force–deformation characteristics, sounds (using an acoustic envelope detector coupled to the texture analyser with a microphone) as well as mechanical vibrations (registered using a piezoelectric sensor) generated during a penetration test. All analysed samples of bread were products with a crisp texture that emitted audible sounds with a significant intensity that could be registered with a microphone as well as with a contact method. Micro-CT cross-section images showed the highly porous structure of the crisp breads but variant 3 appeared to have thicker walls and larger cells than the other breads.  相似文献   

Trophic ecology of speckled peacock bass Cichla temensis Humboldt 1821 in the middle Negro River,Amazon, Brazil          下载免费PDF全文

Jamerson Aguiar‐Santos  Pieter A. P. deHart  Marc Pouilly  Carlos E. C. Freitas  Flávia K. Siqueira‐Souza 《Ecology of Freshwater Fish》2018,27(4):1076-1086

The aim of this study was to analyse the trophic ecology of speckled peacock bass Cichla temensis inhabiting two tributaries of the middle Negro River, the Aracá River and the Demeni River. Using an analysis of stomach contents and stable isotope composition (δ¹⁵N, δ¹³C) of scales, we describe the diet and evaluate the trophic position of subadult and adult individuals. We then test whether diet shifts and trophic positions occurred among successive size classes and among sample locations. The stomach content analysis confirmed the piscivorous feeding habit of the species and showed that the speckled peacock bass preyed on a variety species belonging to different trophic guilds. The length of the ingested prey increased with the size of the speckled peacock bass. Diet composition and trophic position were not different among size classes. δ¹³C values yielded significant shifts among the size classes: larger individuals displayed higher δ¹³C values than smaller individuals. Trophic position varied between locations, with lowest values observed in fish from the Aracá River. This study demonstrated that diet of C. temensis may vary according to the size of the fish, even at the subadult or adult stages, and according to the river/locality, even within a same basin. We then suggest that further studies take into account local availability of food resources to better explore C. temensis diet and tropic ecology.  相似文献   

A staggered maize–legume intercrop arrangement robustly increases crop yields and economic returns in the highlands of Central Kenya     

Monicah Mucheru-Muna  Pieter Pypers  Daniel Mugendi  James Kung’u  Jayne Mugwe  Roel Merckx  Bernard Vanlauwe 《Field Crops Research》2010

Smallholder farmers in East-Africa commonly intercrop maize (Zea mays L.) with grain legumes to maximize utilisation of land and labour, and attain larger crop yields. Conventionally, one legume line is intercropped between each pair of maize lines. This study evaluated the potential of a modified two-by-two staggered arrangement (MBILI) to increase crop yields and economic benefits in two sites in Central Kenya with contrasting soil fertility levels during 7 consecutive seasons. Common beans (Phaseolus vulgaris L.), cowpea (Vigna unguiculata (L.) Walp.) and groundnut (Arachis hypogaea L.) were grown as legume intercrops. The MBILI system resulted in increased maize yields in both sites, and increased cowpea yields in the poor site. In the fertile site, using beans as an intercrop was most profitable, and the MBILI system increased net benefits by 40%, relative to the conventional system. In the poor site, groundnut and cowpea were better adapted, and the MBILI system increased net benefit by 12–37%. Positive effects of the MBILI system were most pronounced in the poor site, but occurred independent of soil fertility level. Rainfall amounts and distribution varied widely, but the MBILI system increased yields both under conditions of ample and inadequate rainfall. N balances were negative with beans and groundnut, but neutral with cowpea as the intercrop. A modest N fertilizer application is therefore essential to sustain yields in the long term, especially when beans or groundnuts are intercropped. In conclusion, the MBILI system, when combined with adjusted nutrient inputs, resulted in superior and robust improvements in crop yields and economic benefits, relative to the conventional intercropping system.  相似文献