bluuebunny/crossref_metadata_2025 huggingface dataset:
Effet de la brûlure cercosporéenne, causée par le Cercospora carotae, sur le développement, la croissance et le rendement de la carotte
Authors: Bourgeois G. , Brodeur C. , Kushalappa A.C.
Published: July 2012

L'objectif de cette étude était de quantifier l'effet de la sévérité de la brûlure cercosporéenne (Cercospora carotae) sur le développement (stades végétatifs), la croissance (poids secs du feuillage et des racines, indice de surface foliaire) et le rendement de la carotte (Daucus carota var. sativa). Au cours d'expériences effectuées en sol organique durant les saisons 1990, 1991 et 1992, trois niveaux de sévérité ont été obtenus par des nombres différents d'applications de fongicides, à savoir aucune application, deux ou trois applications et une application à chaque semaine. Au cours des trois années, des différences entre les traitements ont été observées 60 jours après le semis pour la sévérité de la maladie, 80 jours après le semis pour le poids sec du feuillage et l'indice de surface foliaire, et 100 jours après le semis pour le poids sec des racines. Une augmentation du nombre d'applications a permis une augmentation du rendement total en carottes. Cependant, les applications hebdomadaires n'ont pas augmenté le rendement en carottes de classe régulière par rapport à deux ou trois applications pour l'ensemble de la saison. Il est donc possible de réduire le nombre d'applications de fongicides, tout en conservant un rendement économiquement acceptable.
Managing apple maggot, Rhagoletis pomonella [Diptera : Tephritidae], by perimeter trapping
Authors: Bostanian N.J. , Vincent C. , Chouinard G. , Racette G.
Published: July 2012

Perimeter trapping is an effective physical method to control apple maggot (Rhagoletis pomonella) in apple (Malus pumila) orchards. It provided 99.5 to 100 % clean fruit at harvest in commercial orchards. The traps were red spheres (9 cm diam) or yellow boards (28 cm x 21.5 cm) sandwiched between the two halves of red spheres. They were coated with a sticky material and baited with butyl hexanoate. The number of traps per plot was a function of the length of the plot facing a possible entry site of R. pomonella. In plots adjacent to forest, traps were placed at ca. 10 m intervals on the row, or on the outer most tree of every row. Sides of plots adjacent to prairie grass or a chemically-treated plot had traps at approximately 20-m intervals. To achieve commercially acceptable apple maggot control, the activity of the pest should be low to moderate. Susceptiblity to apple maggot attack varied from one apple cultivar to another. Therefore, this criterion should be considered when perimeter trapping of apple maggot is envisaged.
Use of the growth regulator paclobutrazol in the management of dollar spot of creeping bentgrass in Minnesota
Authors: Mercier J.
Published: July 2012

The control of dollar spot by paclobutrazol applied as a growth regulator on a creeping bentgrass (Agrostis palustris) and annual bluegrass (Poa annua) fairway turf was compared with two standard fungicide treatments in Minnesota during two growing seasons. Paclobutrazol was applied every 3 weeks, staggered by about 10 days with fungicide treatments (chlorothalonil or propiconazole), also applied every 3 weeks. Paclobutrazol alone significantly reduced the number of dollar spot infection centers during both summers, often by as much as 80%. Chlorothalonil or propiconazole were usually more effective in controlling dollar spot than paclobutrazol. Paclobutrazol improved disease control by fungicides when tested in combination with various rates of chlorothalonil or propiconazole. Paclobutrazol applied as a growth regulator could thus be used to reduce the base line severity of dollar spot of turf.
Attract and kill, an effective technique to manage apple maggot, Rhagoletis pomonella [Diptera : Tephritidae] in high density Quebec apple orchards
Authors: Bostanian N.J. , Racette G.
Published: July 2012

"Attract and kill" is an effective technique to control apple maggot (Rhagoletis pomonella) in apple orchards. It provided 98.5 to 100% clean fruit at harvest in McIntosh, Liberty, Royal Gala and Jonagold cvs. The traps consisted of yellow boards (28 cm x 21.5 cm) sandwiched between the two halves of red spheres (9 cm diam). They were sprayed with 12.5 and 6.3% cypermethrin or 1.3 and 1.7% deltamethrin in de-odorized kerosene, loaded with butyl hexanoate in semi-permeable sachets. The traps were hung on branches 1.20-1.70 m above the ground. They were placed on the periphery of the plot and positioned so as to be visible from outside the tree canopy. The number of traps per plot was a function of the length of the plot opposite a possible entry site of apple maggot. In columns opposite a forest, entry site of apple maggot into the plot, the traps in a column were at 2-3 m intervals (0.3-0.5 traps m-1). A trap was also placed on every tree of the first and last row of a column. The columns were 4-5.5 m apart (0.18-0.25 traps m-1). Opposite to prairie grass or a chemically treated plot the traps were at 2-6 m intervals (0.17-0.5 traps m-1) in a column. On the row, the distance between adjacent traps was 4 to 12 m (0.08-0.25 traps m-1). To achieve commercially acceptable apple maggot control in cvs. McIntosh, Liberty, Gala and Jonagold apples with "attract and kill" technique, the activity of the pest should not exceed 13 flies per four traps placed on the periphery of the plot, in other words, 1.6 times the action threshold for the apple maggot in Quebec apple orchards.
Green foxtail (Setaria viridis) resistance to acetolactate synthase inhibitors
Authors: Volenberg D.S. , Stoltenberg D.E. , Boerboom C.M.
Published: July 2012

Green foxtail (Setaria viridis) plants putatively resistant to acetolactate synthase (ALS) inhibitors were identified in a Wisconsin USA no-tillage soybean (Glycine max) field in 1999. Resistance to imidazolinone and sulfonylurea herbicides was characterized at the whole-plant level and enzyme level. Three- to four-leaf stage green foxtail plants were 1020, 53, and 6.5-fold resistant to imazethapyr, imazamox, and nicosulfuron, respectively, compared to susceptible plants. In vivo ALS was 1300 and 1.7-fold resistant to imazethapyr and nicosulfuron, respectively. These results suggested that this green foxtail accession was highly resistant to imazethapyr and imazamox, and that resistance was associated with an insensitive ALS enzyme.
L’histoire nationale au Secondaire
Authors: Lefebvre André
Published: July 2012

Une motion votée par l’Assemblée Nationale du Québec le 27 novembre 1974 obligeait les élèves du secondaire à « s’inscrire... à un cours d’histoire nationale dont le contenu portera sur l’histoire du Canada et, en particulier, sur l’histoire du Québec. » Comme il fallait s’y attendre, l’événement allait provoquer une remise en question de l’enseignement de l’histoire nationale. Comment les enseignants d’histoire nationale voient-ils leur propre enseignement? Quelle idée se font-ils de leurs élèves par rapport à l’histoire nationale? Quelle histoire croient-ils devoir enseigner? Quel programme souhaitent-ils? Selon eux, comment devrait se faire l’évaluation de leur enseignement? Mais ont-ils la liberté de dispenser le meilleur enseignement possible?
L’information scolaire et professionnelle et l’inévitable rupture entre l’école et le marché du travail
Authors: Bengle Normand , Laflamme Claude
Published: July 2012

Le but de cet article est de tenter de démontrer que la rupture entre l’école et le marché du travail relève des contradictions intrinsèques à toute formation sociale capitaliste. Suite à une analyse du système d’enseignement et du marché du travail, les auteurs essaient de tracer une voie nouvelle aux spécialistes de l’orientation étant donné leur rôle d’intermédiaire entre ces deux grandes composantes de la formation sociale québécoise.
Une critique raisonnée de l’approche fonctionnelle
Authors: Rukalski Sigmund
Published: July 2012

Sans être universelle, l’approche fonctionnelle s’avère utile pour certains groupes d’élèves en langue seconde. L’auteur analyse les principes sous-tendant toute situation d’apprentissage et plus particulièrement ceux dont il est nécessaire de tenir compte dans l’enseignement d’une langue seconde. À la lumière de cette analyse, l’approche fonctionnelle se trouve replacée dans les dimensions didactiques qui lui sont propres.
L’ordinateur au secours de l’inadaptation
Authors: Larivée Serge , Michaud Nicole
Published: July 2012

L’utilisation de l’ordinateur à des fins thérapeutiques est une idée relativement récente. Dans un premier temps, les auteurs présentent ici les principes de base d’utilisation du projet Logo mis au point par Papert. Dans un second temps, un exemple vient illustrer les principes énoncés. Dans un troisième volet les auteurs présentent un ensemble de réflexions sur quelques liens entre le projet Logo, le processus d’équilibration de Piaget et la rééducation.
Conception du rôle d’un animateur-leader chez des professionnels ayant déjà des acquis en ce domaine
Authors: St-Yves Aurèle
Published: July 2012

Cette recherche vise à vérifier si des personnes initiées à l’animation et agissant occasionnellement comme animateurs-leaders perçoivent comme également important chacun des niveaux de fonctionnement d’un groupe (contenu, procédure et socio-émotif). Un questionnaire composé de vingt-sept énoncés, soit neuf énoncés se rapportant à chacun des niveaux, a été distribué à une centaine de professionnels de l’information scolaire et professionnelle du Québec. L’analyse des résultats révèle que les répondants privilégient également ces trois niveaux de fonctionnement.
Le processus de sélection et de recrutement dans les universités chinoises depuis 1976
Authors: Richard Monique
Published: July 2012

Cette recherche porte sur les réformes apportées au processus de sélection et de recrutement dans les universités chinoises, depuis 1976. Après un bref retour sur les politiques antérieures, une description et une analyse des causes, de la nature, des obstacles et des conséquences du processus, l’auteure conclut qu’on assiste à une réintroduction modifiée de politiques antérieures à la « révolution culturelle », où l’accent est mis sur des critères académiques. Un ajout de la « révolution culturelle » est cependant conservé : le dossier politique. Résultats : le nombre des entrants est peu élevé, conséquence d’une compétition de plus en plus grande, d’un plus grand nombre d’éligibles et de la faiblesse des ressources humaines et matérielles.
Structuration intérieure d’objets géométriques dans la genèse d’idées spatiales
Authors: Lunkenbein Dieter , Allard Huguette , Goupille Cécile
Published: July 2012

Le présent article résume les conceptions de Piaget et de van Hiele relatives à la genèse et au développement d’idées spatiales. Il montre, par la suite, la complémentarité des deux approches et met en évidence l’importance et la prédominence de structures spatio-visuelles dans la conception initiale d’objets géométriques. Les observations faites lors de l’expérimentation de l’activité de compter les faces de polyèdres sont alors intégrées dans ce contexte théorique en interprétant les procédures de dénombrement en tant que phénomènes révélateurs d’absence ou d’existence, d’émergence ou de développement de structurations intérieures d’objets géométriques chez un individu.
Processus et critères de sélection du directeur d’école au secondaire
Authors: Girard Hermann C.
Published: July 2012

Effectuée dans les douze commissions scolaires de la région administrative de Québec qui offrent le cours secondaire, cette recherche avait comme but de découvrir la nature et le processus du recrutement des nouveaux directeurs d’écoles secondaires. Les conclusions tirées de cette recherche sont les suivantes : il n’y a pas de politiques écrites de sélection, sauf dans une commission; la sélection est le propre d’un groupe restreint, soit les quelques personnes qui assistent à l’entrevue. On attend du futur directeur de polyvalente qu’il soit un gestionnaire; par contre, on recherche un pédagogue pour une école de petite dimension.
Lessons from post‐normal science for climate science‐sceptic debates
Authors: Turnpenny John R.
Published: July 2012

Climate change is a particularly good example of an issue for which the definition of problems, and attempts to resolve them, contain key roles for scientific research, alongside institutions, ideology, and individual beliefs. This can lead to rich empirical questions as to the relative balance of these influences. However, the most visible discussion about the role of scientific knowledge is often a heated and simplistic debate about the details of the science itself. Post‐normal science (PNS) is one way to think about the role of science and expertise more generally in addressing problems like climate change. PNS, it is argued, by extending the group of actors feeding expertise of different types into knowledge‐making and decision processes, can provide a richer and more in‐depth perspective and an extended function of quality control over the process of inquiry. This review introduces the concept of PNS, and some of the responses to it from various quarters. These responses offer valuable insights into the way that scientific expertise is perceived, such as perceptions about why science is used and what scienceshoulddo, focusing in particular on ‘climate science‐sceptic' debates. By introducing insights from science studies, political science, policy analysis, and human geography alongside PNS, the paper offers potential ways out of such debates, and also ways that PNS may develop in the future.WIREs Clim Change2012 doi: 10.1002/wcc.184

This article is categorized under:

Social Status of Climate Change Knowledge > Knowledge and Practice
Discriminant analysis
Authors: McLachlan Geoffrey J.
Published: July 2012

The need for classification arises in most scientific pursuits. Typically, there is interest in ‘classifying’ an entity, say, an individual or object, on the basis of some characteristics (feature variables) measured on the entity. This article focuses on the form of classification known as supervised classification or discriminant analysis. It is applicable in situations where there are data of known origin with respect to the predefined classes from which a classifier can be constructed to assign an unclassified entity to one of these classes. We consider nonparametric and parametric approaches to the construction of classifiers. Consideration is given to recent results on the formation of classifiers in situations where the number of variablespis very large relative to the number of observationsn. Methods for estimating the error rates of a classifier are described, including the situation where the classifier has been formed in some optimal way from a relatively small subset of the variables relative to the available numberp. In such situations care has to be taken to avoid the selection bias inherent in the ordinarily used error‐rate estimators.WIREs Comput Stat2012 doi: 10.1002/wics.1219

This article is categorized under:

Statistical and Graphical Methods of Data Analysis > Multivariate Analysis
Very-low-energy diets and morbidity: a systematic review of longer-term evidence
Authors: Mulholland Y. , Nicokavoura E. , Broom J. , Rolland C.
Published: July 2012

Evidence from the literature supports the safe use of very-low-energy diets (VLED) for up to 3 months in supervised conditions for patients who fail to meet a target weight loss using a standard low-fat, reduced-energy approach. There is, however, a need for longer-term outcomes on obesity and associated morbidities following a VLED. The present systematic review aims to investigate longer-term outcomes from studies using VLED, with a minimum duration of 12 months, published between January 2000 and December 2010. Studies conducted in both children and adults, with a mean/median BMI of ≥ 28 kg/m2 were included. PubMed, MEDLINE, Web of Science and Science Direct were searched. Reference lists of studies and reviews were manually searched. Weight loss or prevention of weight gain and morbidities were the main outcomes assessed. A total of thirty-two out of 894 articles met the inclusion criteria. The duration of the studies ranged from 12 months to 5 years. Periods of VLED ranged from 25 d to 9 months. Several studies incorporated aspects of behaviour therapy, exercise, low-fat diets, low-carbohydrate diets or medication. Current evidence demonstrates significant weight loss and improvements in blood pressure, waist circumference and lipid profile in the longer term following a VLED. Interpretation of the results, however, was restricted and conclusions with which to guide best practice are limited due to heterogeneity between the studies. The present review clearly identifies the need for more evidence and standardised studies to assess the longer-term benefits from weight loss achieved using VLED.
Non-planar ion acoustic Gardner solitons in electron-positron-ion plasma with superthermal electrons and positrons
Authors: GHOSH DEB KUMAR , GHOSH UDAY NARAYAN , CHATTERJEE PRASANTA
Published: July 2012

The properties of non-planar (cylindrical and spherical) ion acoustic solitary waves (IASWs) in an unmagnetized collisionless electron-positron-ion (e-p-i) plasma, whose constituents are inertial ions and superthermal/non-Maxwellian electrons and positrons (represented by the kappa (κ) distribution), are investigated by deriving the modified Gardner (MG) equation. The well-known reductive perturbation method is employed to derive the MG equation. The basic features of non-planar IA Gardner solitons (GSs) are discussed. It is seen that the properties of non-planar IAGSs (positive and negative) differ significantly as the value of spectral index kappa changes.
The neurobiology of food intake in an obesogenic environment
Authors: Berthoud Hans-Rudolf
Published: July 2012

The objective of this non-systematic review of the literature is to highlight some of the neural systems and pathways that are affected by the various intake-promoting aspects of the modern food environment and explore potential modes of interaction between core systems such as hypothalamus and brainstem primarily receptive to internal signals of fuel availability and forebrain areas such as the cortex, amygdala and meso-corticolimbic dopamine system, primarily processing external signals. The modern lifestyle with its drastic changes in the way we eat and move puts pressure on the homoeostatic system responsible for the regulation of body weight, which has led to an increase in overweight and obesity. The power of food cues targeting susceptible emotions and cognitive brain functions, particularly of children and adolescents, is increasingly exploited by modern neuromarketing tools. Increased intake of energy-dense foods high in fat and sugar is not only adding more energy, but may also corrupt neural functions of brain systems involved in nutrient sensing as well as in hedonic, motivational and cognitive processing. It is concluded that only long-term prospective studies in human subjects and animal models with the capacity to demonstrate sustained over-eating and development of obesity are necessary to identify the critical environmental factors as well as the underlying neural systems involved. Insights from these studies and from modern neuromarketing research should be increasingly used to promote consumption of healthy foods.
THE GROUND OF LOCKE'S LAW OF NATURE
Authors: West Thomas G.
Published: July 2012

This essay will show that Locke’s teaching on the law of nature is not based on divine revelation, or a juridical doctrine of individual rights, or self-ownership, or self-preservation, or reasoning from premises that are not rooted in the empirical world. I will argue, on the contrary, that the real ground is found in his understanding of the conditions of human happiness. This conclusion is far from evident on the surface of Locke’s writings. Locke draws his reader into an amazingly complex line of reasoning, scattered up and down in several of his books, leading finally to the real basis of his teaching on the law of nature. Locke engages the reader in a dialogue, in which initially plausible arguments are put forward, then implicitly questioned, leading to new arguments, which again are questioned, and so on. Locke says that “long and sometimes intricate deductions of reason” are necessary to discover the law of nature. Locke writes treatises, not Platonic dialogues. Nevertheless, a dialogical thread will take us from one of Locke’s books to another, until we put together all the relevant passages to show the complete picture of his argument.
MONTESQUIEU'S NATURAL RIGHTS CONSTITUTIONALISM
Authors: Rahe Paul A.
Published: July 2012

When Woodrow Wilson, in the course of his campaign for the Presidency in 1912, attacked Thomas Jefferson and Charles-Louis de Secondat, baron de La Brède et de Montesquieu, he knew what he was about—for the constitutionalism articulated by the latter and embraced, in turn, by the Framers of the American Constitution was a systematic attempt to put into practice something very much like the first principles spelled out in the Declaration of Independence. Montesquieu was not a doctrinaire. He feared that, in his own country and elsewhere, revolution would eventuate in the establishment of a despotism, and so he gently, quietly promoted unobtrusive reform. But the cautious, prudential political science that he outlined in hisSpirit of Lawswas anything but value-free. If the American framers found his legislative science of use, it was because the hatred of despotism and love for liberty animating its author was grounded in an account of natural right closely akin to the one, espoused in John Locke’sTwo Treatises of Government, that had inspired their revolution.
Salmonella entericaserovar Enteritidis phage type 4 outbreak associated with eggs in a large prison, London 2009: an investigation using cohort and case/non-case study methodology
Authors: DAVIES A. R. , RUGGLES R. , YOUNG Y. , CLARK H. , REDDELL P. , VERLANDER N. Q. , ARNOLD A. , MAGUIRE H.
Published: July 2012

In September 2009, an outbreak ofSalmonella entericaserovar Enteritidis affected 327 of 1419 inmates at a London prison. We applied a cohort design using aggregated data from the kitchen about portions of food distributed, aligned this with individual food histories from 124 cases (18 confirmed, 106 probable) and deduced the exposures of those remaining well. Results showed that prisoners eating egg cress rolls were 26 times more likely to be ill [risk ratio 25·7, 95% confidence interval (CI) 15·5–42·8,P<0·001]. In a case/non-case multivariable analysis the adjusted odds ratio for egg cress rolls was 41·1 (95% CI 10·3–249·7,P<0·001). The epidemiological investigation was strengthened by environmental and microbiological investigations. This paper outlines an approach to investigations in large complex settings where aggregate data for exposures may be available, and led to the development of guidelines for the management of future gastrointestinal outbreaks in prison settings.
The predictive significance of early caregiving experiences for symptoms of psychopathology through midadolescence: Enduring or transient effects?
Authors: Haltigan John D. , Roisman Glenn I. , Fraley R. Chris
Published: July 2012

A fundamental question in the discipline of developmental psychopathology is whether early interpersonal experiences influence maladaptation in enduring or transient ways. We address this issue by applying a structural modeling approach developed by us to examine data from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development on maternal sensitivity in the first 3 years of life and its association with symptoms of psychopathology through age 15. Results suggest that there may be enduring effects of early caregiving experiences on symptomatology as rated by teachers, although such effects were not found for maternal report. Additional analyses indicated that enduring associations found via teacher report could not be fully accounted for by continuity in caregiving experiences or by early contextual adversity.
Empowering Society
Authors: Jumani Usha
Published: July 2012

Empowerment is an integral element of a democratic system. The maturity of a democracy is directly related to the level of empowerment its citizens and institutions experience. The term 'empowerment' is used in different contexts and this book addresses this problem through a comparative analysis of three major organisational systems - business, government and social development. The book presents a new conceptual framework for understanding the process of empowerment. It combines case studies specially for this volume, with secondary data and the author's first hand experience of working with development organisations. The differential understanding of empowerment in various organisational contexts helps to promote cross-sectoral learning, and contributes to a qualitative shift in empowering society as a whole.
Intensive Measurement Designs for Research on Aging
Authors: Rast Philippe , MacDonald Stuart W. S. , Hofer Scott M.
Published: July 2012

Intensive measurement burst designs permit analysis of behavioral and biological processes as they unfold over short and long periods of time and providing the opportunity to identify change from an individual’s normative level of functioning. The measurement burst design permits statistical decomposition of short-term variation and learning effects that overlay normative aging and provide stronger bases for detecting accelerated change due to pathological processes. We provide an overview of design features and analysis of measurement burst data in Project MIND. The objective of intensive measurement designs is to obtain greater resolution of processes of interest that permit reliable and sensitive assessments of functioning and change in functioning and of key determinants underlying short-term variation and long-term aging and health-related change.
Innate immune signalling at the intestinal epithelium in homeostasis and disease
Authors: Pott Johanna , Hornef Mathias
Published: July 2012

The intestinal epithelium—which constitutes the interface between the enteric microbiota and host tissues—actively contributes to the maintenance of mucosal homeostasis and defends against pathogenic microbes. The recognition of conserved microbial products by cytosolic or transmembrane pattern recognition receptors in epithelial cells initiates signal transduction and influences effector cell function. However, the signalling pathways, effector molecules and regulatory mechanisms involved are not yet fully understood, and the functional outcome is poorly defined. This review analyses the complex and dynamic role of intestinal epithelial innate immune recognition and signalling, on the basis of results in intestinal epithelial cell‐specific transgene or gene‐deficient animals. This approach identifies specific epithelial cell functions within the diverse cellular composition of the mucosal tissue, in the presence of the complex and dynamic gut microbiota. These insights have thus provided a more comprehensive understanding of the role of the intestinal epithelium in innate immunity during homeostasis and disease.
Population transfer and rapid passage effects in a low pressure gas using a continuous wave quantum cascade laser
Authors: McCormack E. A. , Lowth H. S. , Bell M. T. , Weidmann D. , Ritchie G. A. D.
Published: July 2012

A continuous wave quantum cascade laser (cw-QCL) operating at 10 μm has been used to record absorption spectra of low pressure samples of OCS in an astigmatic Herriott cell. As a result of the frequency chirp of the laser, the spectra show clearly the effects of rapid passage on the absorption line shape. At the low chirp rates that can be obtained with the cw-QCL, population transfer between rovibrational quantum states is predicted to be much more efficient than in typical pulsed QCL experiments. This optical pumping is investigated by solving the Maxwell Bloch equations to simulate the propagation of the laser radiation through an inhomogeneously broadened two-level system. The calculated absorption profiles show good quantitative agreement with those measured experimentally over a range of chirp rates and optical thicknesses. It is predicted that at a low chirp rate of 0.13 MHz ns−1, the population transfer between rovibrational quantum states is 12%, considerably more than that obtained at the higher chirp rates utilised in pulsed QCL experiments.
Fully digital data acquisition system for the neutron time-of-flight spectrometer TOFOR at JET
Authors: Skiba M. , Weiszflog M. , Hjalmarsson A. , Ericsson G. , Hellesen C. , Conroy S. , Andersson-Sundén E. , Eriksson J. , Binda F. ,   JET-EFDA Contributors
Published: July 2012

A prototype of a fully digital data acquisition system based on 1 Gsps 12 bit digitizers for the TOFOR fusion neutron spectrometer at JET is assessed. The prototype system enables the use of geometry-based background discrimination techniques, which are modeled, evaluated, and compared to experimental data. The experimental results are in line with the models and show a significant improvement in signal-to-background ratio in measured time-of-flight spectrum compared to the existing data acquisition system.
Benzene adsorption and the encapsulation processes in SiC nanotubes
Authors: de Oliveira J. B. , Baierle R. J. , Miwa R. H.
Published: July 2012

We have performed a theoretical ab initio study of interaction between benzene molecules and silicon carbide nanotubes (SiCNTs). Two different scenarios have been examined, (1) benzene molecules adsorbed on the SiCNT surface, and (2) benzene molecules encapsulated by SiCNTs. In order to provide a more general picture, for both systems we have considered several geometries and nanotube (NT) chiralities. The calculations were performed by using the density functional theory within the local density approximation. The suitability of such choice has been discussed. In (1), we find that the benzene adsorption on the SiCNT is an exothermic process, with binding energies between 0.3 and 0.4 eV/molecule, and in (2) we obtained binding energies of ∼0.6 eV/molecule, revealing a preference for the benzene encapsulated systems. For both cases, we verify that the SiCNTs are more reactive than the carbon nanotubes (CNTs). There are no chemical bonds at the benzene–SiCNT interface, and in (1) we observe that the benzene molecule is attached to the NT surface mediated by π–π stacking interactions, similar to the benzene–CNT systems. On the other hand, we find that the encapsulation of benzene molecules becomes no longer exothermic for SiCNTs with diameters smaller than ∼9 Å. Further investigations indicate a barrierless process for the benzene encapsulation through an open edge of SiCNT. We find attractive forces of ∼0.4 nN, and there is a dependence on the atomic configuration of the open edge on the nanotube.
Plume splitting and rebounding in a high-intensity CO2 laser induced air plasma
Authors: Chen Anmin , Jiang Yuanfei , Liu Hang , Jin Mingxing , Ding Dajun
Published: July 2012

The dynamics of plasma plume formed by high-intensity CO2 laser induced breakdown of air at atmospheric pressure is investigated. The laser wavelength is 10.6 μm. Measurements were made using 3 ns gated fast photography as well as space and time resolved optical emission spectroscopy. The behavior of the plasma plume was studied with a laser energy of 3 J and 10 J. The results show that the evolution of the plasma plume is very complicated. The splitting and rebounding of the plasma plume is observed to occur early in the plumes history.
Surface doping in pentacene thin-film transistors with few monolayer thick channels
Authors: Hählen Tatjana , Vanoni Claudio , Wäckerlin Christian , Jung Thomas A. , Tsujino Soichiro
Published: July 2012

Molecular surface doping was studied for organic thin film transistors consisting of an active layer of few monolayers pentacene, as prepared by physical vapor deposition. In situ transport measurements with different dopants revealed both positive (tetrafluoro-tetracyanoquinodimethane – F4TCNQ) and negative (manganese(III)-tetraphenylporphyrin-chloride), as well as zero value (cobalt(II)-tetraphenylporphyrin and fullerene) gate threshold shifts. For F4TCNQ, a high doping efficiency of 25% was observed. The maximum gate threshold shift was more than halved with pentacene thickness increasing from 2.5 to 5 monolayers, indicating that the doping effect decays above ∼2.5 monolayers. Charge transfer has been discussed based on complementary x-ray photoelectron experiments.
Highly zero-biased magnetoelectric response in magnetostrictive/piezoelectric composite
Authors: Chen Lei , Li Ping , Wen Yumei , Wang Pan
Published: July 2012

The magnetoelectric (ME) coupling is investigated in laminated composites employing piezoelectric ceramic PZT (PZT-8), iron-nickel-based ferromagnetic alloy with constant elasticity (FeNi-FACE), and soft magnetic amorphous ribbon FeCuNbSiB (Fe73.5Cu1Nb3Si13.5B9). The two different ferromagnetic materials of FeNi-FACE and FeCuNbSiB result in built-in dc magnetic bias (Hdc) due to difference in their magnetic permeability and coercivity. In addition, the relatively high mechanical quality factors (Qm) for FeNi-FACE, PZT-8, and FeCuNbSiB enhance the resonant ME voltage due to an increased effective Qm of ME composite. Hence, a strong resonant ME response at zero-biased dc magnetic field can be obtained. The corresponding ME voltage coefficients (MEVC) at resonance for PZT/FeNi-FACE/FeCuNbSiB (FeFP) composite and FeCuNbSiB/FeNi-FACE/PZT/FeNi-FACE/FeCuNbSiB (FeFPFFe) composites achieve 2.19 V/Oe (27.375 V/cm Oe) and 3.37 V/Oe (42.125 V/cm Oe), respectively, which is ∼102 times higher than that of the previously reported NKNLS-NZF/Ni/NKNLS-NZF trilayer composite.
Carrier transport mechanism at metal/amorphous gallium indium zinc oxides interfaces
Authors: Kim Seongjun , Kim Kyoung-Kook , Kim Hyunsoo
Published: July 2012

We report the carrier transport mechanism of Ni/Au Ohmic contacts to amorphous gallium indium zinc oxides. Despite the expected large barrier height, Ohmic contact could be achieved due to the trap-assisted tunneling associated with localized tail states. Upon thermal annealing, the specific contact resistance was further reduced to 3.28 × 10−4 Ωcm2, accompanied by a change in the predominant transport mechanism from trap-limited conduction to degenerate conduction. The Ohmic mechanism could be explained in terms of the thermionic field emission model, yielding a tunneling parameter of 49 meV, a Schottky barrier height of 0.63 eV, and a barrier width of 5.2 nm.
Sperm capacitation combined with removal of the sperm acrosome and plasma membrane enhances paternal nucleus remodelling and early development of bovine androgenetic embryos
Authors: Xiao Yao , Zhang Hualin , Ahmad Sibtain , Bai Liya , Wang Xiaomin , Huo Lijun , Zhang Xin , Li Wengong , Li Xiang , Yang Liguo
Published: July 2012

The androgenetic embryo is a useful model for functional analysis of the paternal genome during embryogenesis. However, few studies have focused on the factors involved in the suppressed developmental competence of such embryos or why sperm cloning-derived androgenetic embryos fail to develop beyond the morula stage in large domestic animals. To overcome this developmental failure, we tried to improve sperm decondensation, as well as to enhance embryonic development by sperm capacitation and removal of the acrosome and plasma membrane before injection of the spermatozoa. Before injection of the spermatozoa, we quantified the effects of sperm capacitation combined with sperm pretreatment on the acrosome and plasma membrane status. We also evaluated sperm decondensation potential, sperm viability and chromatin integrity. Immunostaining data showed that the sperm acrosome and plasma membrane could be more efficiently removed after capacitation. Dithiothreitol-induced sperm decondensation potential was improved with capacitation and removal of the acrosome and plasma membrane. Although most spermatozoa lost viability after pretreatment, their chromatin remained integrated. The patterns of paternal chromatin remodelling within uncleaved androgenetic embryos and the nucleus morphology of cleaved embryos indicated that capacitation combined with membrane disruption could make injected spermatozoa decondense synchronously not only with each other, but also with the developmental pace of the ooplasm. We successfully produced androgenetic blastocysts, and efficiency increased with sperm pretreatment. In conclusion, sperm decondensation and the early development of androgenetic embryos were enhanced with sperm capacitation and removal of the acrosome and plasma membrane prior to sperm injection.
Social structures depend on innate determinants and chemosensory processing inDrosophila
Authors: Schneider Jonathan , Dickinson Michael H. , Levine Joel D.
Published: July 2012

Flies display transient social interactions in groups. However, whether fly–fly interactions are stochastic or structured remains unknown. We hypothesized that groups of flies exhibit patterns of social dynamics that would manifest as nonrandom social interaction networks. To test this, we applied a machine vision system to track the position and orientation of flies in an arena and designed a classifier to detect interactions between pairs of flies. We show that the vinegar fly,Drosophila melanogaster, forms nonrandom social interaction networks, distinct from virtual network controls (constructed from the intersections of individual locomotor trajectories). In addition, the formation of interaction networks depends on chemosensory cues. Gustatory mutants form networks that cannot be distinguished from their virtual network controls. Olfactory mutants form networks that are greatly disrupted compared with control flies. Different wild-type strains form social interaction networks with quantitatively different properties, suggesting that the genes that influence this network phenotype vary across and within wild-type populations. We have established a paradigm for studying social behaviors at a group level inDrosophilaand expect that a genetic dissection of this phenomenon will identify conserved molecular mechanisms of social organization in other species.
Identification of olivetolic acid cyclase from
Cannabis sativa
reveals a unique catalytic route to plant polyketides
Authors: Gagne Steve J. , Stout Jake M. , Liu Enwu , Boubakir Zakia , Clark Shawn M. , Page Jonathan E.
Published: July 2012

Δ
9
-Tetrahydrocannabinol (THC) and other cannabinoids are responsible for the psychoactive and medicinal properties of
Cannabis sativa
L. (marijuana). The first intermediate in the cannabinoid biosynthetic pathway is proposed to be olivetolic acid (OA), an alkylresorcinolic acid that forms the polyketide nucleus of the cannabinoids. OA has been postulated to be synthesized by a type III polyketide synthase (PKS) enzyme, but so far type III PKSs from cannabis have been shown to produce catalytic byproducts instead of OA. We analyzed the transcriptome of glandular trichomes from female cannabis flowers, which are the primary site of cannabinoid biosynthesis, and searched for polyketide cyclase-like enzymes that could assist in OA cyclization. Here, we show that a type III PKS (tetraketide synthase) from cannabis trichomes requires the presence of a polyketide cyclase enzyme, olivetolic acid cyclase (OAC), which catalyzes a C2–C7 intramolecular aldol condensation with carboxylate retention to form OA. OAC is a dimeric α+β barrel (DABB) protein that is structurally similar to polyketide cyclases from
Streptomyces
species.
OAC
transcript is present at high levels in glandular trichomes, an expression profile that parallels other cannabinoid pathway enzymes. Our identification of OAC both clarifies the cannabinoid pathway and demonstrates unexpected evolutionary parallels between polyketide biosynthesis in plants and bacteria. In addition, the widespread occurrence of DABB proteins in plants suggests that polyketide cyclases may play an overlooked role in generating plant chemical diversity.
Water and sustainable land use at the ancient tropical city of Tikal, Guatemala
Authors: Scarborough Vernon L. , Dunning Nicholas P. , Tankersley Kenneth B. , Carr Christopher , Weaver Eric , Grazioso Liwy , Lane Brian , Jones John G. , Buttles Palma , Valdez Fred , Lentz David L.
Published: July 2012

The access to water and the engineered landscapes accommodating its collection and allocation are pivotal issues for assessing sustainability. Recent mapping, sediment coring, and formal excavation at Tikal, Guatemala, have markedly expanded our understanding of ancient Maya water and land use. Among the landscape and engineering feats identified are the largest ancient dam identified in the Maya area of Central America; the posited manner by which reservoir waters were released; construction of a cofferdam for dredging the largest reservoir at Tikal; the presence of ancient springs linked to the initial colonization of Tikal; the use of sand filtration to cleanse water entering reservoirs; a switching station that facilitated seasonal filling and release; and the deepest rock-cut canal segment in the Maya Lowlands. These engineering achievements were integrated into a system that sustained the urban complex through deep time, and they have implications for sustainable construction and use of water management systems in tropical forest settings worldwide.
Herbivore pressure increases toward the equator
Authors: Salazar Diego , Marquis Robert J.
Published: July 2012

Increases in species diversity and density from higher to lower latitudes are well documented. Nevertheless, the consequences of these changes in diversity for structuring ecological communities and influencing biotic evolution are largely unknown. It is widely believed that this increase in species diversity is associated with increased intensity of ecological interactions closer to the equator. For plant–herbivore interactions in particular, the predictions are that, at lower latitudes, plants will be attacked by more individual herbivores, more herbivore species, and more specialized herbivores and, therefore, will suffer greater damage. We used a large-scale latitudinal transect from Mexico to Bolivia to quantify changes in leaf damage, diversity, and abundance of lepidopteran larvae on two widely distributed host species of the genusPiper(Piperaceae). We show that both density and species richness of herbivores were highest at the equator and decreased with increasing latitude, both northward and southward. Contrary to expectation, however, this increase in herbivore diversity was attributable to the addition of generalist not specialist species. Finally, and again contrary to expectation, the increase in herbivore density with decreasing latitude did not produce a corresponding damage gradient. We propose that the lack of a latitudinal concordance between increases in herbivore density and diversity with decreasing latitude, and the resulting herbivore damage, supports the hypothesis of better plant antiherbivore defenses at lower latitudes. Furthermore, the changes in the relative abundance of generalist vs. specialist species suggest that the nature of the selective pressure is intrinsically different between higher and lower latitudes.
Homeodomain POU and Abd-A proteins regulate the transcription of pupal genes during metamorphosis of the silkworm,
Bombyx mori
Authors: Deng Huimin , Zhang Jialing , Li Yong , Zheng Sichun , Liu Lin , Huang Lihua , Xu Wei-Hua , Palli Subba R. , Feng Qili
Published: July 2012

A cascade of 20-hydroxyecdysone–mediated gene expression and repression initiates larva-to-pupa metamorphosis. We recently showed that two transcription factors, BmPOUM2 and BmβFTZ-F1, bind to the
cis
-regulatory elements in the promoter of the gene coding for cuticle protein, BmWCP4, and regulate its expression during
Bombyx mori
metamorphosis. Here we show that down-regulation of
BmPOUM2
expression by RNA interference during the wandering stage resulted in failure to complete metamorphosis. The thorax epidermis of RNA interference-treated larvae became transparent, wing disc growth and differentiation were arrested, and the larvae failed to spin cocoons. Quantitative real-time PCR analysis showed that expression of the genes coding for pupal-specific wing cuticle proteins BmWCP1, BmWCP2, BmWCP3, BmWCP4, BmWCP5, BmWCP6, BmWCP8, and BmWCP9 were down-regulated in
BmPOUM2
dsRNA-treated animals, whereas overexpression of BmPOUM2 protein increased the expression of
BmWCP4
,
BmWCP5
,
BmWCP6
,
BmWCP7
, and
BmWCP8
. Pull-down assays, far-Western blot, and electrophoretic mobility shift assay showed that the BmPOUM2 protein interacted with another homeodomain transcription factor, BmAbd-A, to induce the expression of
BmWCP4
. Immunohistochemical localization of BmPOUM2, BmAbd-A, and BmWCP4 proteins revealed that BmAbd-A and BmPOUM2 proteins are colocalized in the wing disc cell nuclei, whereas BmWCP4 protein is localized in the cytoplasm. Together these data suggest that BmPOUM2 interacts with the homeodomain transcription factor BmAbd-A and regulates the expression of
BmWCP4
and probably other
BmWCPs
to complete the larva-to-pupa transformation. Although homeodomain proteins are known to regulate embryonic development, this study showed that these proteins also regulate metamorphosis.
Manipulating the drug/proton antiport stoichiometry of the secondary multidrug transporter MdfA
Authors: Tirosh Osnat , Sigal Nadejda , Gelman Amir , Sahar Nadav , Fluman Nir , Siemion Shira , Bibi Eitan
Published: July 2012

Multidrug transporters are integral membrane proteins that use cellular energy to actively extrude antibiotics and other toxic compounds from cells. The multidrug/proton antiporter MdfA from
Escherichia coli
exchanges monovalent cationic substrates for protons with a stoichiometry of 1, meaning that it translocates only one proton per antiport cycle. This may explain why transport of divalent cationic drugs by MdfA is energetically unfavorable. Remarkably, however, we show that MdfA can be easily converted into a divalent cationic drug/≥2 proton-antiporter, either by random mutagenesis or by rational design. The results suggest that exchange of divalent cationic drugs with two (or more) protons requires an additional acidic residue in the multidrug recognition pocket of MdfA. This outcome further illustrates the exceptional promiscuous capabilities of multidrug transporters.
Structural basis for intersubunit signaling in a protein disaggregating machine
Authors: Biter Amadeo B. , Lee Sukyeong , Sung Nuri , Tsai Francis T.F.
Published: July 2012

ClpB is a ring-forming, ATP-dependent protein disaggregase that cooperates with the cognate Hsp70 system to recover functional protein from aggregates. How ClpB harnesses the energy of ATP binding and hydrolysis to facilitate the mechanical unfolding of previously aggregated, stress-damaged proteins remains unclear. Here, we present crystal structures of the ClpB D2 domain in the nucleotide-bound and -free states, and the fitted cryoEM structure of the D2 hexamer ring, which provide a structural understanding of the ATP power stroke that drives protein translocation through the ClpB hexamer. We demonstrate that the conformation of the substrate-translocating pore loop is coupled to the nucleotide state of thecissubunit, which is transmitted to the neighboring subunit via a conserved but structurally distinct intersubunit-signaling pathway common to diverse AAA+ machines. Furthermore, we found that an engineered, disulfide cross-linked ClpB hexamer is fully functional biochemically, suggesting that ClpB deoligomerization is not required for protein disaggregation.