Home About us Contact
|
Home About us Contact | ||
|
|
||
Cutting
Kinds of Cutting Terms modified by Cutting Selected AbstractsInvestigations into the Sealing of Heat Damaged Areas by Applying Polymer Powders During Laser Cutting of Carbon Fiber Reinforced Composites,ADVANCED ENGINEERING MATERIALS, Issue 7 2010Peter Jaeschke Endless carbon fiber reinforced plastics are recognized as having the greatest lightweight construction potential of all materials. Fully automated process chains for the manufacturing of composite structures are needed in order to achieve production rates and cycle times required in many industrial sectors. In this paper, a new technique, based on the in situ sealing of the kerf during high power laser cutting by application of polymer powder is presented. The degree of sealing is analyzed as a function of powder mass flow as well as carrying gas flow and it is shown that moisture uptake can be reduced compared to unsealed laser cut specimens. [source] Graphene Shape Control by Multistage Cutting and TransferADVANCED MATERIALS, Issue 44 2009Lijie Ci Cutting graphene by a catalytic hydrogenation process can generate graphene pieces with smooth edges of atomic precision and well-defined shapes. Controlled cutting of graphene by creating graphene step edges by oxidation or plasma etching is demonstrated. A combination of cutting, transfer, and lithography is shown to allow the fabrication of isolated graphene devices with specific edge and shape control. [source] Near-Infrared Quantum Cutting for PhotovoltaicsADVANCED MATERIALS, Issue 30 2009Bryan M. van der Ende Efficient quantum cutting by the Pr3+,Yb3+ couple is demonstrated for the conversion of blue/green to near-infrared (NIR) radiation with quantum efficiencies close to 200%. The resonant two-step energy transfer process, which involves one higher-energy photon becoming two NIR photons, may lead to the reduction of energy loss in solar cells, revealing how spectral conversion is a promising avenue for boosting solar-cell efficiency. [source] Cutting through the statistical fog: understanding and evaluating non-inferiority trialsINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 10 2010W. S. Weintraub Summary Every year, results from many important randomised, controlled trials are published. Knowing the elements of trial design and having the skills to critically read and incorporate results are important to medical practitioners. The goal of this article is to help physicians determine the validity of trial conclusions to improve patient care through more informed medical decision making. This article includes a review of 162 randomised, controlled non-inferiority (n = 116) and equivalence (n = 46) hypothesis studies as well as the larger Stroke Prevention using Oral Thrombin Inhibitor in atrial Fibrillation V study and the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial. Evaluation of data from small and large trials uncovers significant flaws in design and models employed and uncertainty about calculations of statistical measures. As one example of questionable study design, discussion includes a large (n = 3922), double-blind, randomised, multicentre trial comparing the efficacy of ximelagatran with warfarin for prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation and additional stroke risk factors. Investigators concluded that ximelagatran was effective compared with well-controlled warfarin for prevention of thromboembolism. However, deficiencies in design, as well as concerns about liver toxicity, resulted in the rejection of the drug by the US Food and Drug Administration. Many trials fail to follow good design principles, resulting in conclusions of questionable validity. Well-designed non-inferiority trials can provide valuable data and demonstrate efficacy for beneficial new therapies. Objectives and primary end-points must be clearly stated and rigorous standards met for sample size, establishing the margin, patient characteristics and adherence to protocol. [source] Surveillance and risk factors of norovirus gastroenteritis among children in a southern city of China in the fall,winter seasons of 2003,2006JOURNAL OF PAEDIATRICS AND CHILD HEALTH, Issue 1-2 2010Ying-Chun Dai Aim: Noroviruses (NoVs) are an important cause of acute gastroenteritis but knowledge on the disease burden and epidemiology in children in the developing countries remains limited. In this study, we performed a surveillance of NoV gastroenteritis in children of China to address some of the questions. Methods: Faecal specimens from children (<5 years of age) at outpatient clinics of the Nan Fang Hospital in Guangzhou, China during the fall,winter seasons in 2003,2006 were tested for rotaviruses (RVs) and NoVs. A questionnaire on clinical records and hygiene habits was collected from each patient. Results: Among 957 stool specimens tested, 488 (51%) specimens were positive for RVs. NoVs were detected in 112 (24%) of the 469 RV negative specimens. The Genogroup II (GII), particularly GII-4, viruses were predominant. No significant difference of clinical symptoms, hospitalisation and patient care expenses were found between children infected with NoVs and RVs. Consumption of uncooked food is a risk for NoV infection. Contact with diarrhoea patients is a suspected risk factor. Cutting nails frequently is a protective factor against NoV infection. Conclusions: NoVs are an important cause of acute gastroenteritis in children which need special attention of patient care at the clinics in addition to RVs. The awareness of those risk factors may help future disease control and prevention. [source] Prediction of cutting effects on a population of Chaerophyllum aureum, a demographic approachJOURNAL OF VEGETATION SCIENCE, Issue 4 2000D. Magda Abstract. A demographic study of the undesirable perennial weed Chaerophyllum aureum in extensified French Pyrenean hay meadows was carried out. For two successive years the effect of date and intensity of cutting on the population demography of this colonizer. Population density is sensitive to cutting practices essentially through fecundity, seedling survival rate and seed dispersal between fields. Cutting reduces fecundity by preventing seed formation (early cutting) or by exportation of some mature seeds with hay (late cutting). Nevertheless, the number of seeds transported between field populations by hay harvest, organic manuring and associated cutting practices compensates for the lack of seed production in early-cut populations, maintaining them at relative high densities. For each of three cutting regimes, the number of immigrant and emigrant seeds has been indirectly estimated from a prediction of population density at equilibrium from demographic parameters measured in field populations and compared with observed population densities. [source] Feminism and Women's Autonomy: the Challenge of Female Genital CuttingMETAPHILOSOPHY, Issue 5 2000Diana Tietjens Meyers Feminist studies of female genital cutting (FGC) provide ample evidence that many women exercise effective agency with respect to this practice, both as accommodators and as resisters. The influence of culture on autonomy is ambiguous: women who resist cultural mandates for FGC do not necessarily enjoy greater autonomy than do those women who accommodate the practice, yet it is clear that some social contexts are more conducive to autonomy than others. In this paper, I explore the implications for autonomy theory of these understandings of the relation between culture, FGC, and women's agency. I review the range of worldwide FGC practices , including "corrective" surgery for "ambiguous genitalia" in Western cultures as well as the various initiation rites observed in some African and Asian cultures , and the diverse cultural rationales for different forms of FGC. I argue that neither latitudinarian, value-neutral accounts of autonomy nor restrictive, value-saturated accounts adequately explain women's agentic position with respect to FGC. I then analyze a number of educational programs that have enhanced women's autonomy, especially by strengthening their introspection, empathy, and imagination. Such programs, which engage women's autonomy skills without exposing them to autonomy-disabling cultural alienation, promote autonomy-within-culture. This understanding of autonomy as socially situated, however, entails neither endorsement of FGC nor resignation to its persistence. [source] Population in the UN Environment Programme's Global Environment Outlook 2000POPULATION AND DEVELOPMENT REVIEW, Issue 3 2000Article first published online: 27 JAN 200 Most specialized agencies in the United Nations system have taken to compiling a periodic status report on their field. The UN Environment Programme (UNEP) issued the first in a proposed biennial series in 1998, titled Global Environment Outlook-1 or GEO-1. The second in the series, Global Environment Outlook 2000, was published in 1999. GEO-2000 is described by the UNEP's Executive Director, Klaus Töpfer, in the foreword as "a comprehensive integrated assessment of the global environment at the turn of the millennium, [and] a forward-looking document, providing a vision into the 21st century." Its status, however, is rendered uncertain by the printed caution that "The contents of this volume do not necessarily reflect the views or policies of UNEP or contributory organizations." GEO-2000 paints a generally bleak picture of environmental trends. It evidences a wide array of particulars ("In the Southern Ocean, the Patagonian toothfish is being over-fished and there is a large accidental mortality of seabirds caught up in fishing equipment"), but perhaps of more import are its statements about the root causes of environmental problems and what must be done. The excerpts below reflect some of these general views as they pertain to population. They are taken from the section entitled "Areas of danger and opportunity" in Chapter 1 of the report, and from the section "Tackling root causes" in Chapter 5. High resource consumption, fueled by affluent, Western lifestyles, is seen as a basic cause of environmental degradation. Cutting back this consumption will be required, freeing up resources for development elsewhere. Materialist values associated with urban living are part of the problem, given the concentration of future population growth in cities. And "genuine globalization" will entail free movement of people as well as capital and goods, thus optimizing "the population to environmental carrying capacity." Some of these positions are at least questionable: the supposed "innate environmental sensitivity of people raised on the land or close to nature," or the aim of "globalization of population movements." The latter does not appear in the recommendations, perhaps because of an implicit assumption that the effect of open borders on environmental trends is unlikely to be favorable. (For an earlier statement of the same sentiment,from 1927,see the comments by Albert Thomas, first director of the ILO, reproduced in the Archives section of PDR 9, no. 4.) [source] Toward responsive visualization services for scatter/gather browsingPROCEEDINGS OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE & TECHNOLOGY (ELECTRONIC), Issue 1 2008Weimao Ke As a type of relevance feedback, Scatter/Gather demonstrates an interactive approach to relevance mapping and reinforcement. The Scatter/Gather model, proposed by Cutting, Karger, Pedersen, and Tukey (1992), is well known for its effectiveness in situations where it is difficult to precisely specify a query. However, online clustering on a large data corpus is computationally complex and extremely time consuming. This has prohibited the method's real world application for responsive services. In this paper, we proposed and evaluated a new clustering algorithm called LAIR2, which has linear worst-case time complexity and constant running time average for Scatter/Gather browsing. Our experiment showed when running on a single processor, the LAIR2 online clustering algorithm is several hundred times faster than a classic parallel algorithm running on multiple processors. The efficiency of the LAIR2 algorithm promises real-time Scatter/Gather browsing services. We have implemented an online visualization prototype, namely, LAIR2 Scatter/Gather browser, to demonstrate its utility and usability. [source] Trans -splicing in DrosophilaBIOESSAYS, Issue 11 2002Vincenzo Pirrotta Splicing is an efficient and precise mechanism that removes noncoding regions from a single primary RNA transcript. Cutting and rejoining of the segments occurs on nascent RNA. Trans -splicing between small specialized RNAs and a primary transcript has been known in some organisms but recent papers show that trans -splicing between two RNA molecules containing different coding regions is the normal mode in a Drosophila gene.1,3 The mod(mdg4) gene produces 26 different mRNAs encoding as many protein isoforms. The differences lie in alternative 3, exons encoded by different transcriptional units and spliced to the 5, common region by a surprising trans -splicing mechanism. BioEssays 24:988,991, 2002. © 2002 Wiley-Periodicals, Inc. [source] Cutting to cope , a modern adolescent phenomenonCHILD: CARE, HEALTH AND DEVELOPMENT, Issue 5 2010B. Hall Abstract Background The frequency of young people cutting themselves appears to be increasing, with one review estimating the current prevalence across the UK to be between 1 in 12 and 1 in 15. Aim To identify factors that are associated with self-harm by cutting, and more especially coping strategies that if encouraged might reduce such behaviour. Method Multivariate and exploratory factor analysis were used to analyse the results from a survey of the pupils attending four large comprehensive schools in the North of England where the frequency of cutting behaviour was causing concern. Results Three factors were identified from the analysis , Social & Active Coping, Seeking External Solutions and Non-Productive Coping. The Social & Active Coping was the only factor that significantly correlated with non-cutting behaviour. Conclusions The fostering of the elements that make up Social & Active Coping , namely working successfully and feeling a sense of achievement, together with positive friendship networks and positive diversions, including physical recreation, will help to minimize young people's sense of needing to cope by cutting themselves. [source] Interacting effects of CO2 partial pressure and temperature on photosynthesis and calcification in a scleractinian coralGLOBAL CHANGE BIOLOGY, Issue 11 2003Stéphanie Reynaud Abstract We show here that CO2 partial pressure (pCO2) and temperature significantly interact on coral physiology. The effects of increased pCO2 and temperature on photosynthesis, respiration and calcification rates were investigated in the scleractinian coral Stylophora pistillata. Cuttings were exposed to temperatures of 25°C or 28°C and to pCO2 values of ca. 460 or 760 ,atm for 5 weeks. The contents of chlorophyll c2 and protein remained constant throughout the experiment, while the chlorophyll a content was significantly affected by temperature, and was higher under the ,high-temperature,high- pCO2' condition. The cell-specific density was higher at ,high pCO2' than at ,normal pCO2' (1.7 vs. 1.4). The net photosynthesis normalized per unit protein was affected by both temperature and pCO2, whereas respiration was not affected by the treatments. Calcification decreased by 50% when temperature and pCO2 were both elevated. Calcification under normal temperature did not change in response to an increased pCO2. This is not in agreement with numerous published papers that describe a negative relationship between marine calcification and CO2. The confounding effect of temperature has the potential to explain a large portion of the variability of the relationship between calcification and pCO2 reported in the literature, and warrants a re-evaluation of the projected decrease of marine calcification by the year 2100. [source] The Influence Of Salinity On Verticillium dahliae In Stem Cuttings Of Five Olive CultivarsJOURNAL OF PHYTOPATHOLOGY, Issue 10 2007A. G. Levin Abstract Verticillium dahliae represents one of the main limiting factors in olive production in the Mediterranean countries. Increasing shortage of fresh water and land, increase the pressure on using alternative sources of marginal or saline water, and land previously cropped with V. dahliae host plants. The objective of the present study was to evaluate the influence of salinity on V. dahliae expression in olive stem cuttings. V. dahliae- inoculated cuttings of cvs. Picual, Frantoio, Mansanillo and Barnea, showed higher senescence symptoms than their non-inoculated controls. Colonization levels obtained in cv. Picual were significantly higher than in cv. Frantoio. Manzanillo was the most sensitive cultivar to salinity alone, with significant senescence symptoms in 4 and 6 dS/m NaCl treatments. When cv. Manzanillo was exposed to both salinity and V. dahliae, significantly higher senescence symptoms were obtained as compared with each of them separately. Senescence symptoms of cv. Picual exposed to V. dahliae, whether or not in combination with saline solutions, were significantly higher than those when cuttings were exposed to a saline solution alone. In cv. Frantoio, which is more resistant to salinity than the other cultivars, significantly high senescence symptoms were observed only in combination of V. dahliae and high saline concentration (8 dS/m). The fungal colonization index in cv. Manzanillo in high salinity (8 dS/m) was significantly higher than in the treatment without salt. In cv. Barnea, colonization index in 8 dS/m salinity was significantly higher than in the 4 dS/m concentration or control (fresh water). In conclusion, our findings demonstrate the interaction between V. dahliae and saline irrigation in various cultivars. Thus, stem cuttings could serve as an effective screening method in breeding olive clones for V. dahliae resistance, salt tolerance and their interaction. [source] Responses of Nondormant Black Willow (Salix nigra) Cuttings to Preplanting Soaking and Soil MoistureRESTORATION ECOLOGY, Issue 1 2005S. R. Pezeshki Abstract The use of willow cuttings for streambank stabilization is a common practice in riparian ecosystems throughout the United States. Many environmental factors govern the outcome of such planting. However, other factors such as preplanting treatments, planting methods, and physiological status of cuttings (dormant vs. actively growing) may also be crucial in determining the survival of willow cuttings. Actively growing (nondormant) Black willow (Salix nigra) cuttings, 30 cm in length and 1 cm in diameter at the base, were subjected to three soaking treatments (0, 7, and 15 days) prior to planting. Following the initial treatment, cuttings were grown in a greenhouse in pots under three soil moisture regimes (well-watered but not flooded, permanently flooded, and intermittently flooded). Plant gas exchange, growth, biomass, and survival were measured. Results demonstrated that soaking for 7 days was beneficial to early development of cuttings in the well-watered (control) soil moisture regime, enhancing percent bud flush and survival significantly. However, 15 days of soaking proved to be detrimental to survival of cuttings irrespective of soil moisture regimes. Results also demonstrated that the beneficial effects of 7-day soaking were limited to the well-watered soil moisture regime but not to the flooded or intermittently flooded regimes. Soaking nondormant cuttings may be worthwhile if the planting site is likely to present ample soil moisture but nonflooded conditions to the transplanted cuttings. [source] A Quantitative Conservation Approach for the Endangered Butterfly Maculinea alconCONSERVATION BIOLOGY, Issue 2 2004MICHIEL F. WallisDeVries The quality and size of habitat patches and their isolation from other patches are the main parameters for an assessment of population persistence, but translating persistence probabilities into practical measures is still a weak link in conservation management. I provide a quantitative conservation approach for the endangered myrmecophilous butterfly Maculinea alcon in the Netherlands. All 127 colonies known on heathland since 1990 were investigated for patch quality, size, and isolation. I assessed habitat quality in three 10 × 10 m plots for most colonies. Site occupancy in 1998,1999 was only 56%. Occupancy was best explained by a logistic regression including patch area, host ant presence, host plant abundance, overall heathland area, and connectivity between sites ( R2= 0.410, p < 0.0001); it correctly classified the occupied or vacant status for 82% of the sites. Connectivity contributed only 3.6% to the total explained variation of site occupancy, indicating that habitat characteristics were more important than isolation in determining population persistence at the examined scale level (>500 m). Grazing and sod cutting had a beneficial impact, but in combination these practices proved detrimental. Hydrological measures to prevent drainage were also associated with lowered occupancy. I used the different components in the logistic regression to formulate objective management recommendations. These consisted of sod cutting, reduction of management intensity, enlargement of habitat, or combinations of these recommendations. The results highlight the importance of careful management when site quality is determined by multiple factors. The quantitative conservation approach followed here can be fruitfully extended to other endangered species, provided enough is known about their ecological requirements and how management actions affect them. Resumen:,La preservación de fragmentos individuales es extremadamente importante para especies en peligro con capacidad de dispersión limitada. La calidad y tamaño de los fragmentos de hábitat y su aislamiento de otros fragmentos son los parámetros principales para la evaluación de la persistencia de la población, pero la traducción de probabilidades de persistencia en medidas prácticas aun es un eslabón débil en la gestión de conservación. Proporciono un método cuantitativo de conservación para la mariposa mirmecófila Maculinea alcon en peligro en Holanda. Se investigó a las 127 colonias conocidas en brezales desde 1990 para calidad, tamaño y aislamiento del fragmento. Evalué la calidad del hábitat en tres parcelas de 10 × 10 m en la mayoría de las colonias. La ocupación de sitios en 1998-1999 fue sólo 56%. La ocupación fue mejor explicada por regresión logística incluyendo la superficie del fragmento, presencia de hormigas huésped, abundancia de plantas huésped, superficie total del brezal y conectividad entre sitios ( R2= 0.410, p < 0.0001); clasificó el estatus de ocupado o vacante en 82% de los sitios. La conectividad contribuyó con solo 36% de la variación total de sitio de ocupación, lo que indica que las características de hábitat fueron más importantes que el aislamiento en la determinación de la persistencia de la población en el nivel de escala examinado (>500 m). El pastoreo y el corte de pasto tuvieron un impacto benéfico pero combinadas, estas prácticas fueron perjudiciales. Obras hidrológicas para prevenir la desecación también se asociaron con una disminución en la ocupación. Utilicé los diferentes componentes de la regresión logística para formular recomendaciones objetivas de gestión. Estas incluyeron el corte de pasto, reducción en la intensidad de manejo, aumento de hábitat o combinaciones de estas recomendaciones. Los resultados resaltan la importancia de la gestión cuidadosa cuando la calidad del sitio está determinada por múltiples factores. El método cuantitativo de preservación utilizado puede ser extendido exitosamente a otras especies en peligro, siempre que sean suficientemente conocidos sus requerimientos ecológicos y la forma en que le afectan las acciones de manejo. [source] Effect of the cutting technique on the residual stress distribution of cut edges in FeSi3 transformer sheetsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 11 2009M. Böhling Abstract Samples of laser-scratched FeSi3 transformer sheets have been investigated. The investigations were carried out by using the Kossel and EBSD techniques in our self-designed multifunctional system. The results show residual stress mappings of the cut edges of FeSi3 transformer sheets and their dependence on the cutting process (conventional plate shears, abrasive water-jet technique, laser cutting). (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Smaller and more numerous harvesting gaps emulate natural forest disturbances: a biodiversity test case using rove beetles (Coleoptera, Staphylinidae)DIVERSITY AND DISTRIBUTIONS, Issue 6 2008Jan Klimaszewski ABSTRACT Aim To evaluate changes in the abundance, species richness and community composition of rove beetles (Coleoptera, Staphylinidae) in response to three configurations of experimental gap cuts and to the effects of ground scarification in early succession yellow birch-dominated boreal forest. In each experimental treatment, total forest removed was held constant (35% removal by partial cutting with a concomitant decrease in gap size) but the total number of gaps was increased (two, four and eight gaps, respectively), resulting in an experimental increase in the total amount of ,edge' within each stand. Location Early succession yellow birch-dominated forests, Quebec, Canada. Methods Pitfall traps, ANOVA, MIXED procedure in sas®, post hoc Tukey's adjustment, rarefaction estimates, sum-of-squares and distance-based multivariate regression trees (ssMRT, dbMRT). Results Estimates of species richness using rarefaction were highest in clearcut and two-gap treatments, decreased in smaller and more numerous gaps and were significantly higher in scarified areas than in unscarified areas. ANOVA indicated a significant impact of harvesting on the overall standardized catch. Post hoc Tukey's tests indicated that the total catch of all rove beetles was significantly higher in uncut forests than in the treated areas. Both sum-of-squares and distance-based multivariate regression trees indicated that community structure of rove beetles differed among treatments. Assemblages were grouped into (a) control plots, (b) four- and eight-gap treatments and (c) two-gap and clearcut treatments. Main conclusions Rove beetle composition responded significantly to increasing gap size. Composition among intermediate and small-sized gap treatments (four- and eight-gap treatments) was more similar to uncut control forests than were larger gap treatments (two-gap) and clearcuts. Effects of scarification were nested within the harvested treatments. When the total area of forest removed is held constant, smaller, more numerous gaps are more similar to uncut control stands than to larger gaps and falls more closely within the natural forest heterogeneity. [source] Alcohol policy in South Africa: a review of policy development processes between 1994 and 2009ADDICTION, Issue 8 2010Charles D. H. Parry ABSTRACT Background Implementation of effective policies to reduce harmful alcohol consumption requires both a good understanding of the policy development process and which strategies are likely to work. Aims To contribute to this understanding by reviewing four specific policy development initiatives that have taken place in South Africa between 1994 and 2009: restrictions on alcohol advertising and counter-advertising, regulation of retail sales of alcohol, alcohol taxation and controls on alcohol packaging. Methods Material was drawn from a record of meetings and conferences held between 1994 and 2009 and a database of reports, newspaper clippings and policy documentation. Findings When the policy process resulted in a concrete outcome there was always a clear recognition of the problem and policy alternatives, but success was more likely if there was an alignment of ,political' forces and/or when there was a determined bureaucracy. The impact of the other factors such as the media, community mobilization, non-governmental organizations (NGOs), the liquor industry and research are also discussed. Future avenues for policy research are identified, including the need for more systematic studies that give greater consideration to economic factors. Conclusions Alcohol policy development in South Africa takes place in a piecemeal fashion and is the product of various competing influences. Having a comprehensive national alcohol strategy cutting across different sectors may be a better way for other developing countries to proceed. [source] Sabotaging behaviour and minimal latex of Asclepias curassavica incur no cost for larvae of the southern monarch butterfly Danaus erippusECOLOGICAL ENTOMOLOGY, Issue 4 2010DANIELA RODRIGUES 1. The southern monarch, Danaus erippus, uses mainly Asclepias curassavica as its host in the Neotropics, a plant species bearing articulated anastomosing laticifers. When artificially severed, A. curassavica has been shown to release significantly less latex than other Asclepias species. 2. The present study tested the hypothesis that sabotaging behaviour changes during the ontogeny of D. erippus and recorded latex outflow of A. curassavica during sabotaging and feeding. Larvae displayed vein-cutting behaviour, which was initially observed in the second instar, became more pronounced in the third and fourth instars, and less frequent in the fifth instar. When present, latex outflow was never more than 1 µl at a time during either vein cutting or feeding, regardless of the instar. 3. Mandibular and midrib morphometrics revealed that larvae selected thicker midrib sites for severing as instars progressed; however, no correlation between mandibular size and midrib size severed was found within instars. 4. Costs of sabotaging behaviour and the effects of A. curassavica latex outflow on D. erippus larvae were also examined. Sabotaging behaviour did not incur growth costs for larvae, and only latex exudation volumes at least 10-fold greater than those observed due to D. erippus sabotaging or feeding, caused significantly higher larval mortality than controls. 5. Since latex outflow is minimal or non-existent in A. curassavica, sabotaging behaviour in D. erippus is mostly limited by morphological constraints and is probably driven by chemical stimulants rather than latex defence. In turn, latex does not constitute a major defence of A. curassavica against D. erippus. [source] New role for majors in Atta leafcutter antsECOLOGICAL ENTOMOLOGY, Issue 5 2007SOPHIE E. F. EVISON Abstract 1.,Atta (Hymenoptera: Formicidae) leafcutter ants display the most polymorphic worker caste system in ants, with different sizes specialising in different tasks. The largest workers (majors) have large, powerful mandibles and are mainly associated with colony defence. 2.,Majors were observed cutting fallen fruit and this phenomenon was investigated in the field by placing mango fruit near natural Atta laevigata and Atta sexdens colonies in São Paulo State, Brazil. 3.,Ants cutting the fruit were significantly heavier (mean = 49.1 mg, SD = 11.1 mg, n= 90) than the ants carrying the fruit back to the nest (mean = 20.9 mg, SD = 9.2 mg, n= 90). 4.,Fruit pieces cut by majors were small (mean = 15.9 mg), approximately half the weight of leaf pieces (mean = 28.5 mg) cut and carried by media foragers. It is hypothesised that it is more difficult to cut large pieces from three-dimensional objects, like fruit, compared to two-dimensional objects, like leaves, and that majors, with their longer mandibles, can cut fruit into larger pieces than medias. 5.,The study shows both a new role for Atta majors in foraging and a new example of task partitioning in the organisation of foraging. [source] Effect of Plant Factors, Sugar Contents, and Control Methods on the Top Borer (Scirpophaga nivella F.) Infestation in Selected Varieties of SugarcaneENTOMOLOGICAL RESEARCH, Issue 3 2005Abdul KHALIQ ABSTRACT Sugarcane (Saccharum officinarum L.) varieties CP-43/33 and L-118 susceptible, BF-162 and SPSG-26 resistant while CP-72/2086 as intermediate were screened for studies on top borer, Scirpophaga nivella Fabricus (Pyralidae: Lepidoptera). Morpho-physio chemical plant factors as well as quality of sugar were examined to elucidate the relationship between pest infestations. The observations on leaf thickness 0.735* and moisture contents 0.771* showed positive and significant correlation with the pest infestation at tillering stage. Total minerals, manganese and copper contents did not show significant correlation with the pest infestation, whereas nitrogen, potassium, calcium, magnesium and ferrous contents manifested positive and significant correlation with the pest infestation. Phosphorous, carbohydrates, fats and zinc produced significant and adverse effect on the pest infestation at tillering stage. Zinc contents with contrasting behaviors appeared to be the most important character with co-efficient value of 0.764 followed by ferrous with positive sign. The effect of borer infestation was significantly negative on pol (sucrose), Brix contents (total soluble solids), and CCS (commercial cane sugar). The coefficient of determination value was 0.821, obtained by computing fiber content, pol, Brix and CCS factors together for multivariate regression models. Application of trash mulching at the time of sowing proved to be the most effective treatment with minimum infestation (3.91%) of borer and maximum protection level (62.87%) followed by Furadan®, removal of dead hearts + spike thrust, hand collection of egg masses, and cutting of shoots at 15 days interval. [source] Load-bearing capacity of all-ceramic posterior four-unit fixed partial dentures with different zirconia frameworksEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2007Philipp Kohorst The aim of this in vitro study was to compare the load-bearing capacity of posterior four-unit fixed partial dentures (FPDs) produced with two different yttria-stabilized polycrystalline tetragonal zirconia (Y-TZP) ceramics, one being a presintered material, the other a fully sintered, hot isostatically pressed material. Additionally, as a novel approach, the influence of preliminary mechanical damage upon the fracture force of an FPD has been investigated. A total of 20 frameworks each were milled from presintered zirconia and from fully sintered zirconia. Prior to veneering, 10 frameworks of each material were ,damaged' by a defined saw cut similar to an accidental flaw generated during shape cutting. Before fracture testing, all FPDs were subjected to thermal and mechanical cycling. Additionally, scanning electron microscopy was used to investigate fracture surfaces. Statistical analysis showed that FPDs milled from fully sintered zirconia had a significantly higher fracture resistance compared with specimens made from presintered material, whereas preliminary damage did not have a significant effect. After aging, FPDs made from both materials were capable of withstanding occlusal forces reported in the literature. Therefore, both types of Y-TZP may be suitable for posterior four-unit all-ceramic FPDs, although further prolonged aging experiments and prospective clinical trials are required to prove their fitness for clinical use. [source] Crystalline , -Alumina Deposited in an Industrial Coating Unit for Demanding Turning Operations,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2010Kirsten Bobzin Crystalline PVD ,-Al2O3 - coatings offer great potential for their use in high-speed cutting operations. They promise high hot hardness and high oxidation resistance at elevated temperatures. This is important for coatings that are used for machining of materials with low thermal conductivity such as stainless steel or Inconel 718 because heat generated during cutting can barely be dissipated by the chip. Because of the prevailing bonding forces of alumina, adhesion-related sticking can be reduced even for dry cutting. Furthermore, the high formation enthalpy of alumina prevents chemical reactions with frictional partners. The present work gives an overview of the deposition of ,-Al2O3 thin films on WC/Co-cutting inserts by using pulsed MSIP (magnetron sputter ion plating) PVD technology. To improve adhesion, a (Ti,Al)N bond coat was employed. The samples were analyzed using common thin film test equipment. Cutting tests and pin-on-disk examinations were carried out to test the coating's performance. For turning operations, the difficult-to-machine austenitic steel 1.4301 (X5CrNi18-10) was used. In comparison to a state-of-the-art (Ti,Al)N coating, (Ti,Al)N/,-Al2O3 showed a longer tool life. [source] The effects of stream canopy management on macroinvertebrate communities and juvenile salmonid production in a chalk streamFISHERIES MANAGEMENT & ECOLOGY, Issue 2 2009W. D. RILEY Abstract, The effects of changes in shading (through riparian canopy removal and re-growth) on juvenile salmon, Salmo salar L., trout, Salmo trutta L., and grayling, Thymallus thymallus (L.) populations, and macroinvertebrate biomass and species composition in a chalk stream in southern England were examined. Low levels of in-stream weed growth, because of shading by closed tree canopy, diminished macroinvertebrate production and diversity. 0+ salmon and trout had lower densities under closed canopy, relative to adjacent open sites with substantial weed cover, where fish were also found to be larger. Canopy removal positively affected the growth of aquatic macrophytes and the availability of potential prey for juvenile salmonids. The findings have implications for the management of chalk streams, in particular, that riparian tree canopy should be managed to prevent complete closure, and excessive cutting of weed should be avoided where salmon production is below sustainable levels. [source] Effects of stream restoration and management on plant communities in lowland streamsFRESHWATER BIOLOGY, Issue 1 2006TINA CHARLOTTE MOUSTGAARD PEDERSEN Summary 1. We evaluated restoration success on macrophyte species diversity and composition in lowland streams using communities in 30 naturally meandering stream reaches in the western part of Jutland, Denmark, as reference target communities. Fuzzy set clustering was used to examine the floristic and environmental similarity among reaches, whereas fuzzy set ordination was used to relate floristic patterns to environmental variables. 2. Two major groups of streams were identified based on their floristic composition. One group consisted of reference and restored reaches and the other of the majority of channelised reaches. We found that management exerted a strong influence on the macrophyte communities and that the identified groups were related to differences in management intensity. 3. Our results also indicate that bank morphology and bed level affected macrophyte communities in the streams, particularly the richness and abundance of terrestrial species. The analyses performed suggest that shallow and wide banks allow for a larger migration of species from the stream banks into the streams, thereby enhancing species diversity within the stream channel. 4. The results of this study suggest that macrophyte communities in channelised lowland streams can recover following restorative interventions given that stream management (i.e. weed cutting and dredging) is minimised and that stream banks are reprofiled to improve the lateral connectivity between the stream and its valley. [source] High-Performance Photoresponsive Organic Nanotransistors with Single-Layer Graphenes as Two-Dimensional ElectrodesADVANCED FUNCTIONAL MATERIALS, Issue 17 2009Yang Cao Abstract Graphene behaves as a robust semimetal with the high electrical conductivity stemming from its high-quality tight two-dimensional crystallographic lattice. It is therefore a promising electrode material. Here, a general methodology for making stable photoresponsive field effect transistors, whose device geometries are comparable to traditional macroscopic semiconducting devices at the nanometer scale, using cut graphene sheets as 2D contacts is detailed. These contacts are produced through oxidative cutting of individual 2D planar graphene by electron beam lithography and oxygen plasma etching. Nanoscale organic transistors based on graphene contacts show high-performance FET behavior with bulk-like carrier mobility, high on/off current ratio, and high reproducibility. Due to the presence of photoactive molecules, the devices display reversible changes in current when they are exposed to visible light. The calculated responsivity of the devices is found to be as high as ,8.3,A,W,1. This study forms the basis for making new types of ultrasensitive molecular devices, thus initiating broad research interest in the field of nanoscale/molecular electronics. [source] On strike-slip faulting in layered mediaGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2002Maurizio Bonafede Summary We study the effects of structural inhomogeneities on the stress and displacement fields induced by strike-slip faults in layered media. An elastic medium is considered, made up of an upper layer bounded by a free surface and welded to a lower half-space characterized by different elastic parameters. Shear cracks with assigned stress drop are employed as mathematical models of strike-slip faults, which are assumed to be vertical and planar. If the crack is entirely embedded within the lower medium (case A), a Cauchy-kernel integral equation is obtained, which is solved by employing an expansion of the dislocation density in Chebyshev polynomials. If the crack is within the lower medium but it terminates at the interface (case B), a generalized Cauchy singularity appears in the integral kernel. This singularity affects the singular behaviour of the dislocation density at the crack tip touching the interface. Finally, the case of a crack crossing the interface is considered (case C). The crack is split into two interacting sections, each placed in a homogeneous medium and both open at the interface. Two coupled generalized Cauchy equations are obtained and solved for the dislocation density distribution of each crack section. An asymptotic study near the intersection between the crack and the interface shows that the dislocation densities for each crack section are bounded at the interface, where a jump discontinuity is present. As a corollary, the stress drop must be discontinuous at the interface, with a jump proportional to the rigidity contrast between the adjoining media. This finding is shown to have important implications for the development of geometrical complexities within transform fault zones: planar strike-slip faults cutting across layer discontinuities with arbitrary stress drop values are shown to be admissible only if the interface between different layers becomes unwelded during the earthquake at the crack/interface junction. Planar strike-slip faulting may take place only in mature transform zones, where a repetitive earthquake cycle has already developed, if the rheology is perfectly elastic. Otherwise, the fault cannot be planar: we infer that strike-slip faulting at depth is plausibly accompanied by en-echelon surface breaks in a shallow sedimentary layer (where the stress drop is lower than prescribed by the discontinuity condition), while ductile deformation (or steady sliding) at depth may be accommodated by multiple fault branching or by antithetic faulting in the upper brittle layer (endowed with lower rigidity but higher stress). [source] Climatic signals in growth and its relation to ENSO events of two Prosopis species following a latitudinal gradient in South AmericaGLOBAL CHANGE BIOLOGY, Issue 5 2006BERNAT C. LÓPEZ Abstract Semiarid environments throughout the world have lost a major part of their woody vegetation and biodiversity due to the effects of wood cutting, cattle grazing and subsistence agriculture. The resulting state is typically used for cattle production, but the productivity of these systems is often very low, and erosion of the unprotected soil is a common problem. Such dry-land degradation is of great international concern, not only because the resulting state is hardly productive but also because it paves the way to desertification. The natural distribution of the genus Prosopis includes arid and semiarid zones of the Americas, Africa and Asia, but the majority of the Prosopis species are, however, native to the Americas. In order to assess a likely gradient in the response of tree species to precipitation, temperature and their connection to El Niño southern oscillation (ENSO) events, two Prosopis species were chosen along a latitudinal gradient in Latin America, from northern Peru to central Chile: Prosopis pallida from a semi-arid land in northern and southern Peru and P. chilensis from a semiarid land in central Chile. Growth rings of each species were crossdated at each sampling site using classical dendrochronological techniques. Chronologies were related with instrumental climatic records in each site, as well as with SOI and N34 series. Cross-correlation, spectral and wavelet analysis techniques were used to assess the relation of growth with precipitation and temperature. Despite the long distance among sites, the two Prosopis species presented similar responses. Thus, the two species' growth is positively correlated to precipitation, while with temperature it is not. In northern Peru, precipitation and growth of P. pallida present a similar cyclic pattern, with a period of around 3 years. On the other hand, P. pallida in southern Peru, and P. chilensis also present this cyclic pattern, but also another one with lower frequency, coinciding with the pattern of precipitation. Both cycles are within the range of the ENSO band. [source] Influence of cutting regime and fertilizer application on the botanical composition, yield and nutritive value of herbage of wet grasslands in Central EuropeGRASS & FORAGE SCIENCE, Issue 4 2009Abstract The changes in dry matter (DM) yield, botanical composition and nutritive value of herbage to ruminants of two wet grasslands, Arrhenatherum elatius grassland (Experiment 1) and a Molinia caerulea fen meadow (Experiment 2), in which a range of cutting and fertilizer treatments were imposed in 1999, were assessed after 4,7 years of treatment imposition. Both experiments had a split-plot design with four replicates. In Experiment 1 the three main-plot cutting treatments were two cuts with a delayed first cut, three cuts and four cuts during the growing season of each year. In Experiment 2 the cutting treatments were two cuts with a traditional harvest time, two cuts with a delayed first cut and three cuts. The four sub-plot fertilizer treatments were an unfertilized control, application of a phosphorus and potassium (PK) fertilizer, application of a nitrogen (N) and PK fertilizer to the first cut only (N1PK) and application of PK plus N applied to each of two, three or four cuts (NcPK). Application of fertilizer influenced yield and botanical composition of herbage more than the cutting treatments while the opposite occurred for nutritive value of the herbage. Application of fertilizer increased the proportion of tall grasses in Experiment 1 and forbs in Experiment 2. The proportion of Equisetum palustre, present only in Experiment 1, was reduced from 0·33 to less than 0·01 by increased cutting frequency together with the NPK fertilizer treatments. In Experiment 1 diversity of vascular plants was negatively affected only by the four-cuts treatment while on both wet grasslands other cutting and fertilizer application treatments had no effect. Changes in DM yield of herbage caused by the cutting and fertilizer application treatments were similar for both vegetation types with DM yield increased significantly by fertilizer application but only slightly or not reduced by increasing the cutting frequency. Nutritive value of herbage was positively correlated with cutting frequency and was most influenced at the first cut. [source] Manipulation of herbage production by altering the pattern of applying nitrogen fertilizerGRASS & FORAGE SCIENCE, Issue 1 2008D. Hennessy Abstract The redistribution of herbage production during the growing season to synchronize herbage supply with feed demand by livestock by altering the application pattern of a range of nitrogen (N) fertilizer rates was studied. Application rates of N were 50, 150 and 250 kg N ha,1 per annum and patterns were with 0·60 of N fertilizer applied before June (treatment RN) and with only 0·20 of N fertilizer before June (treatment IN). Treatments were imposed in a cutting (simulated grazing) experiment (Experiment 1), which was conducted for 2 years and a grazing experiment (Experiment 2) which was conducted for 3 years. In both experiments, herbage production was reduced in April and May and increased in the June,October period on treatment IN relative to RN, but annual herbage production was not significantly affected except in the third year of Experiment 2, when treatment RN had significantly (P < 0·05) higher herbage production than treatment IN. Crude protein (CP) concentration of herbage was lower in April and May on treatment IN than treatment RN. However, CP concentration of herbage was rarely below 150 g kg,1 DM and so it is unlikely that livestock productivity would be compromised. On treatment IN, concentrations of CP in herbage were higher in the late summer than on treatment RN, which may increase livestock productivity during July and August when livestock productivity is often lower. Altering the strategy of application of N fertilizer did not affect in vitro dry matter digestibility of herbage. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||