The coincidence of thrips and dispersed pollen in PNRSV-infected stonefruit orchards - a precondition for thrips-mediated transmission via infected pollen

Recent laboratory studies have demonstrated that Prunus necrotic ringspot virus (PNRSV) (family Bromoviridae) can be readily transmitted when thrips and virus-bearing pollen are placed together on to test plants. For this transmission mechanism to result in stonefruit tree infection in the field, PNRSV-bearing pollen must be deposited onto surfaces of stonefruit trees on which thrips also occur. In a previous paper, we demonstrated that almost all pollen in a PNRSV-infected Japanese plum orchard in southeastern Queensland was deposited onto flowers, whereas few grains occurred on leaves and none on stems. Here, we present results of our investigation of thrips species composition, distribution and abundance on stonefruit trees in the same study area as our previous pollen deposition study. We collected a total of 2010 adult thrips from 13 orchards during the 1989, 1991 and 1992 flowering seasons of which all but 14 were in the suborder Terebrantia. Most (97.4%) terebrantian thrips were of three species, Thrips imaginis, Thrips australis and Thrips tabaci. Thrips tabaci as well as species mixtures that included T imaginis, T australis and T tabaci have been shown to transmit PNRSV via infected pollen in laboratory tests. Adult thrips were frequently collected from flowers but rarely from leaves and never from stems. Large and significant differences in numbers of T imaginis, T australis and T tabaci adults in flowers occurred among orchards and between seasons. No factor was conclusively related to thrips numbers but flowers of late-flowering stonefruit varieties tended to hold more thrips than those of early-flowering varieties. Our results indicate that the common thrips species present on stonefruit trees in the Granite Belt are also ones previously shown to transmit PNRSV via infected pollen in the laboratory and that these thrips are concentrated in stonefruit flowers where most stonefruit pollen is deposited. These results contribute to mounting circumstantial evidence that stonefruit flowers may be inoculated with PNRSV via an interaction of thrips with virus-bearing pollen and that this transmission mechanism may be an important cause of new tree infections in the field.

Mental Well-being at Work. A Sign of a Healthy Organisation and a Necessary Precondition for Organisational Development

One of the aims of the study was to clarify the reliability and validity of the Job Diagnostic Survey (JDS) and the Eigenzustand (EZ) method as measures of the objective characteristics of work and short-term mental work load in the Finnish data. The reliability and validity were examined taking into consideration the theoretical backgrounds of the methods and the reliability of the measurements. The methods were used for finding out the preconditions for organisational development based on self-improvement and clarifying the impacts of working environment (organisational functioning and job characteristics) on a worker’s mental state and health. The influences were examined on a general level - regardless of individual personal or specific contextual factors. One aim was also to clarify how cognitions and emotions are intertwined and how they influence a person’s perception of the working environment. The data consisted of 15 blue-collar organisations in the public sector. The organisations were divided in target and comparison groups depending on the research frames. The data was collected by questionnaires by post. The exploratory and confirmatory factor analyses (Lisrel) were used as the main statistical methods in examining the structures of the methods and impacts between the variables. It was shown that it is possible for organisations to develop their working conditions themselves on specific preconditions. The advance of the development processes could be shown by the amount of the development activity as well as by the changes of the mental well-being (ability to act) and sick absenteeism of the personnel. It was found that the JDS and the EZ methods were reliable and valid measures in the Finnish data. It was shown that, in addition to the objective working environment (organisational functioning and job characteristics), also such a personal factor as selfesteem influences a person’s perception of mental work load. However, the influence did not seem to be direct. The importance of job satisfaction as a general indicator of perceived working conditions was emphasised. Emotional and cognitive factors were found to be functionally intertwined constituting a common factor. Organisational functioning and the characteristics of work had connections with a person’s health measured by sick absenteeism.

Regulated irrigation of woody ornamentals to improve plant quality and precondition against drought stress

Regulated irrigation has the potential to improve crop quality in woody ornamentals by reducing excessive vigour and promoting a more compact habit. This research aimed to compare the effectiveness and the mode of action of two techniques, regulated deficit irrigation (RDI) and partial root drying (PRD), when applied to container-grown ornamentals through drip irrigation. Results showed that RDI and PRD reduced growth in Cotinus coggygria 'Royal Purple', but in Forsythia x intermedia 'Lynwood', significant reductions were recorded only with RDI. Physiological measurements in Forsythia indicated that reductions in stomatal conductance (g(s)) occurred in both treatments, but those in the RDI tended to be more persistent. Reduced g(s) in PRD was consistent with the concept that chemical signals from the root can regulate stomatal aperture alone; however, the data also suggested that optimising the growth reduction required a moderate degree of shoot water deficit (i.e. a hydraulic signal to be imposed). As RDI was associated with tissue water deficit, it was used in a second experiment to determine the potential of this technique to precondition container-grown plants against subsequent drought stress (e.g. during retail stages or after planting out). Speed of acclimation would be important in a commercial context, and the results demonstrated that both slow and rapid imposition of RDI enabled Forsythia plants to acclimate against later drought events. This article discusses the potential to both improve ornamental plant quality and enhance tolerance to subsequent adverse conditions through controlled, regulated irrigation.

Making Energy Interventions more Effective : Situation, Interaction, and Precondition

A main purpose of this paper is to propose to policy makers, building professionals, and other non-social scientists a way to make energy interventions more culturally informed and, thereby, more effective. The case study on house purchasers gives an ample illustration of the richer results that can be achieved by paying attention to three aspects of energy efficiency initiatives: the contexts and situations of choice in each particular case, the interaction among relevant social actors, and the culture-specific preconditions for choice. Research on how purchasers of new pre-fabricated houses in Sweden choose their heating system show how such decisions tend to fall between two stools. Furthermore, the organizational structure of housing companies frames house purchasers' decision making. An important result is that energy saving or conversion measures must be promoted at an early stage amongst those who plan and construct buildings (rather than later amongst dwellers and energy end users).

Vágyott kultúra és reális értékítélet - Tudásmenedzsment-rendszer kiépítésének előfeltétele egy felsőoktatási intézményben (Desired culture and real value judgement – Precondition of development a knowledge management system in a higher education institution)

A tudásmenedzsment-rendszerek kiépítése és működtetése egyre népszerűbb vállalati cél. A legnagyobb igyekezet ellenére is kudarccal végződhet egy ilyen változás megvalósítása, ha a szükséges feltételek nélkül próbálkozunk ezzel a beavatkozással a szervezet életében. Az egyik legfontosabb előfeltétel a bizalomra, közös tanulásra, fejlődésre épülő, nyitott szervezeti kultúra, mely a tanulószervezeti jellemzőkkel írható le. A szerzők kutatásukban arra voltak kíváncsiak, milyen elképzeléseik, vágyaik vannak a felsőoktatásban oktató kollégáknak az ideálisnak nevezett szervezeti kultúráról. Ezeket az elképzeléseket egy külső tanácsadó cég által végzett kérdőíves felmérésen alapuló vizsgálat segítségével tudták meg, melynek kiértékelésére a circumplex-módszer szolgált. Az eredményeket összevetették a tanulószervezeti jellemzőkkel, vizsgálva azt a hipotézist, miszerint az oktató kollégák tudat alatt is olyan ideális szervezetet képzelnek el, mely a tanulószervezeti kultúra jellemzőivel azonos. _________ To create and to operate a knowledge management system is becoming a more and more popular target of the companies. Realizing the changes above can result in a failure – in spite of the biggest will – if organizations lack certain prerequisites which are necessary in companies’ lives. One of the most important prerequisites is organizational culture which can be characterized by confidence, common learning, development and open atmosphere. This is called a learning organizational culture. In their research the authors would have liked to know what kind of dreams the colleagues have about their own organizational culture. They achieve these results from an investigation with questionnaires which were realized by an advisory team. To evaluating the results of this investigation circumplex method was used. These results were compared with the characteristics of learning organization to confirm our hypothesis. According to this idea colleagues have the same images about their successful organization as the characteristics of learning organizations.

Suspension of apatite particles in a self-aerated Denver laboratory flotation cell

Effective solids suspension is a necessary precondition for particle collection, and solids suspension is largely dependent on the hydrodynamics of the flotation cell. This study attempted to correlate the status of the suspension of apatite particles of different sizes in a Denver laboratory flotation cell versus the impeller rotational speed (N) adopted to operate the machine. The latter variable (N) influences the impeller capacity to lift the particles from the bottom of the tank and also to disperse them throughout the volume of the vessel. Such an impeller capacity can be characterized by the critical impeller speed for the accomplishment of solids off-bottom suspension (N(z)) and also by the velocity of the radial water flow discharged by the impeller (U) divided by the particle terminal settling velocity (U(s)). This way, the status of the suspension of apatite particles inside the flotation cell can be characterized by one of three categories: ""segregation"" (N/N(2) < 0.60 and U(s)/U > 0.08); ""suspension"" (0.60 <= N/N(2) < 1 and 0.06 < U(s)/U < 0.10); and ""dragging"" (N/N(2) >= 1 and U(s)/U <= 0.03). The range of impeller rotational speed (N), which was able to suspend the finest particles (D(p) = 90,mu m), was unable to suspend the coarsest particles (D(P) = 254 mu m). Conversely, the high value of N (N > 1,300 rpm), which is adequate to suspend the coarsest particles, may promote the entrainment of the finest particles to the froth layer.

A coiled-coil region of an insect immune suppressor protein is involved in binding and uptake by hemocytes

Polydnaviruses are associated with certain parasitoid wasps and are introduced into the body cavity of the host caterpillar during oviposition. Some of the viral genes are expressed in host tissues and corresponding proteins are secreted into the hemocoel causing suppression of the host immune system. The Cotesia rubecula polydnavirus gene product, CrV1, effectively inactivates hemocytes by mediating cytoskeleton break-down. A precondition for the CrV1 function is the incorporation of the extracellular protein by hemocytes. Here, we show that a coiled-coil domain containing a putative leucine zipper is required for CrV1 function, since removal of this domain abolishes binding and uptake of the CrV1 protein by hemocytes. (C) 2002 Elsevier Science Ltd. All rights reserved.

Supporting contexts in program refinement

A program can be refined either by transforming the whole program or by refining one of its components. The refinement of a component is, for the main part, independent of the remainder of the program. However, refinement of a component can depend on the context of the component for information about the variables that are in scope and what their types are. The refinement can also take advantage of additional information, such as any precondition the component can assume. The aim of this paper is to introduce a technique, which we call program window inference, to handle such contextual information during derivations in the refinement calculus. The idea is borrowed from a technique, called window inference, for handling context in theorem proving. Window inference is the primary proof paradigm of the Ergo proof editor. This tool has been extended to mechanize refinement using program window inference. (C) 1997 Elsevier Science B.V.

Portugal’s Minho-Lima region as a tourist destination: tourism operators’ attitudes towards its management and promotion

The success of tourism development depends on the capacity of a region’s tourism agents to establish and sustain networks, involving both private-sector companies and the public sector. Creating an attractive destination able to compete with others that are better positioned and consolidated requires cooperative behaviour among the various agents involved. This behaviour will facilitate both external and internal competition, which in turn will assure better product quality, continuous product renewal, a strong offer of unique experiences and the efficient use of endogenous resources. In this paper, the authors discuss the results of a survey of restaurant owners and of interviews conducted with the main institutional agents concerned with tourism promotion and the economic development of the Minho–Lima region. Such an approach, the authors argue, can be valuable in identifying the strengths and weaknesses of the area in question with regard to future tourism development. The authors work from the premise that the commitment of tourism agents constitutes a precondition for the success of the strategy to be defined. This is especially applicable to Minho–Lima, which to date has suffered from an absence of commitment and coordination on the part of those agents.

FUNGI ISOLATED FROM THE EXCRETA OF WILD BIRDS IN SCREENING CENTERS IN PELOTAS, RS, BRAZIL

The identification of the fungal species belonging to the healthy microflora in animals is a precondition for the recognition of pathological processes causing them. The aim of this study was to investigate the presence of potentially pathogenic fungi in the feces of wild birds collected in Screening Centers. Samples were collected from the feces of 50 cages with different species of birds. The samples were processed according to the modified method STAIB and the plates incubated at 32 °C for up to ten days with daily observation for detection of fungal growth. The isolation of the following species was observed: Malassezia pachydermatis, Candida albicans, C. famata, C. guilliermondii, C. sphaerica, C. globosa, C. catenulata, C. ciferri, C. intermedia, Cryptococcus laurentii, Trichosporon asahii, Geotrichum klebahnii, Aspergillus spp., A. niger and Penicillium spp. Knowing the character of some opportunistic fungi is important in identifying them, facilitating the adoption of preventive measures, such as proper cleaning of cages, since the accumulation of excreta may indicate a risk for both health professionals and centers for screening public health.

Do Legal Immigrants and Natives Compete in the Labour Market? Evidence from Catalonia

The precondition for labour-market competition between immigrants and natives is that both are willing to accept jobs that do not differ in quality. To test this hypothesis, in this paper we compare the working conditions between immigrants and natives in Catalonia. Comparing immigrants’ working conditions in relation to their native counterparts is not only a useful analysis for studying the extent to which immigrants and low-skilled native workers are direct competitors in the labour market, but also allows us to contribute to the literature on this issue by moving away from the conventional approach used in previous studies. Our results indicate that: i) natives and immigrants display a different taste for job (dis)amenities; ii) Catalan-born workers might be in direct competition with EU15 immigrants, while non-Catalan Spanish workers might be competing with Latin American immigrants, and; iii) African-born immigrants are the group in the Catalan workforce that by far face the worst working conditions.

Involvement of environmental mercury and lead in the etiology of neurodegenerative diseases.

The incidence of neurodegenerative disease like Parkinson's disease and Alzheimer's disease (AD) increases dramatically with age; only a small percentage is directly related to familial forms. The etiology of the most abundant, sporadic forms is complex and multifactorial, involving both genetic and environmental factors. Several environmental pollutants have been associated with neurodegenerative disorders. The present article focuses on results obtained in experimental neurotoxicology studies that indicate a potential pathogenic role of lead and mercury in the development of neurodegenerative diseases. Both heavy metals have been shown to interfere with a multitude of intracellular targets, thereby contributing to several pathogenic processes typical of neurodegenerative disorders, including mitochondrial dysfunction, oxidative stress, deregulation of protein turnover, and brain inflammation. Exposure to heavy metals early in development can precondition the brain for developing a neurodegenerative disease later in life. Alternatively, heavy metals can exert their adverse effects through acute neurotoxicity or through slow accumulation during prolonged periods of life. The pro-oxidant effects of heavy metals can exacerbate the age-related increase in oxidative stress that is related to the decline of the antioxidant defense systems. Brain inflammatory reactions also generate oxidative stress. Chronic inflammation can contribute to the formation of the senile plaques that are typical for AD. In accord with this view, nonsteroidal anti-inflammatory drugs and antioxidants suppress early pathogenic processes leading to Alzheimer's disease, thus decreasing the risk of developing the disease. The effects of lead and mercury were also tested in aggregating brain-cell cultures of fetal rat telencephalon, a three-dimensional brain-cell culture system. The continuous application for 10 to 50 days of non-cytotoxic concentrations of heavy metals resulted in their accumulation in brain cells and the occurrence of delayed toxic effects. When applied at non-toxic concentrations, methylmercury, the most common environmental form of mercury, becomes neurotoxic under pro-oxidant conditions. Furthermore, lead and mercury induce glial cell reactivity, a hallmark of brain inflammation. Both mercury and lead increase the expression of the amyloid precursor protein; mercury also stimulates the formation of insoluble beta-amyloid, which plays a crucial role in the pathogenesis of AD and causes oxidative stress and neurotoxicity in vitro. Taken together, a considerable body of evidence suggests that the heavy metals lead and mercury contribute to the etiology of neurodegenerative diseases and emphasizes the importance of taking preventive measures in this regard.

Towards reusability and tailorability in collaborative learning systems using IMS-LD and grid services

CSCL applications are complex distributed systems that posespecial requirements towards achieving success in educationalsettings. Flexible and efficient design of collaborative activitiesby educators is a key precondition in order to provide CSCL tailorable systems, capable of adapting to the needs of eachparticular learning environment. Furthermore, some parts ofthose CSCL systems should be reused as often as possible inorder to reduce development costs. In addition, it may be necessary to employ special hardware devices, computational resources that reside in other organizations, or even exceed thepossibilities of one specific organization. Therefore, theproposal of this paper is twofold: collecting collaborativelearning designs (scripting) provided by educators, based onwell-known best practices (collaborative learning flow patterns) in a standard way (IMS-LD) in order to guide the tailoring of CSCL systems by selecting and integrating reusable CSCL software units; and, implementing those units in the form of grid services offered by third party providers. More specifically, this paper outlines a grid-based CSCL system having these features and illustrates its potential scope and applicability by means of a sample collaborative learning scenario.