966 resultados para Endosperm absence
Resumo:
Effective detection of population trend is crucial for managing threatened species. Little theory exists, however, to assist managers in choosing the most cost-effective monitoring techniques for diagnosing trend. We present a framework for determining the optimal monitoring strategy by simulating a manager collecting data on a declining species, the Chestnut-rumped Hylacola (Hylacola pyrrhopygia parkeri), to determine whether the species should be listed under the IUCN (World Conservation Union) Red List. We compared the efficiencies of two strategies for detecting trend, abundance, and presence-absence surveys, underfinancial constraints. One might expect the abundance surveys to be superior under all circumstances because more information is collected at each site. Nevertheless, the presence-absence data can be collected at more sites because the surveyor is not obliged to spend a fixed amount of time at each site. The optimal strategy for monitoring was very dependent on the budget available. Under some circumstances, presence-absence surveys outperformed abundance surveys for diagnosing the IUCN Red List categories cost-effectively. Abundance surveys were best if the species was expected to be recorded more than 16 times/year; otherwise, presence-absence surveys were best. The relationship between the strategies we investigated is likely to be relevant for many comparisons of presence-absence or abundance data. Managers of any cryptic or low-density species who hope to maximize their success of estimating trend should find an application for our results.
Resumo:
Agrin is a proteoglycan secreted by motor neurite terminals that functions to initiate and maintain AChR clusters at the nerve terminal. This led to the theory that neurite terminals decide where neuromuscular synapses form by secreting agrin. However, initiation of AChR clustering occurs in the absence of the innervating motoneuron and in the absence of agrin. In this instance, the muscle, not the nerve, is deciding the location of neuromuscular synapses by drawing neurite terminals towards pre-existing AChR clusters. If this were true, one would expect the initial innervation patterns to be the same in agrin-deficient mice and wild-type mice. To test this we quantified the intramuscular axonal branching and synapse formation in the diaphragm at E14.5 in agrin-deficient mice and wild-type mice. Heterozygote mothers were anaesthetised with Nembutal (30 mg) and killed via cervical dislocation. In the diaphragm, the nerve trunk runs down the centre of the muscle and extends branches primarily toward the lateral side. In agrin-deficient mice however, we found significantly more branches exited the phrenic nerve trunk, branched in the periphery and extended further on the medial side. Moreover, we found that the percentage α-bungarotoxin/synaptophysin colocalisations, markers of pre- and postsynaptic differentiation, respectively, was the same in agrin-deficient mice and wild-type mice. These results show that initial innervation patterns are not the same in agrin-deficient mice and wild-type mice indicating neurite terminals, not muscle, decide the placement of neuromuscular synapses in the absence of agrin.
Resumo:
This paper aims to broaden the present CSR literature by extending its focus to the absence of CSR within a developing country, an area which, to date, is relatively under researched in comparison to the more widely studied presence of CSR within developed Western countries. In particular this paper concentrates upon the lack of disclosure on three particular eco-justice issues: child labour, equal opportunities and poverty alleviation. We critically examine why this is the case and thereby illuminate underlying motives behind corporate unwillingness to address these issues. For this purpose, 23 semi-structured interviews were undertaken with senior corporate managers in Bangladesh. The findings suggest that the main reasons for non-disclosure include lack of legal requirements, lack of knowledge/awareness, poor performance and fear of bad publicity. Given these findings the paper raises some serious concerns as to why corporations would ever be expected to voluntarily report on eco-justice issues where performance is poor and negative publicity would be generated. These significant issues require careful consideration by policy makers at the national, regional and international levels.
Resumo:
In Europe local authorities often work with their neighbouring municipalities, whether to address a specific task or goal or through the course of regular policy making and implementation. In England, however, inter-municipal co-operation (IMC) is less common. Councils may work with service providers from the private and non-profit sectors but less often with neighbouring local authorities. Why this is the case may be explained by a number of historical and policy factors that often encourage councils to compete, rather than to work collaboratively with each other. The present government has encouraged councils to work in partnership with other organizations but there are few examples of increased horizontal cooperation between local authorities. Instead the prevailing model remains fixed on vertical co-working predicated on a principal-agent relationship between higher and lower tiers of government.
Resumo:
Uncertified absence from work has traditionally been difficult to link to personality. The present paper argues that personality is best conceptualized as influencing an individual’s intention to be absent from work because of reasons that are within their control. This was investigated in an employed community sample of 128 individuals. These individuals used a self-report measure to express their future intentions to be absent from work as a result of several reasons. These reasons for absence were categorized as “being absent because of external pressure or commitment” (ABCo) and “being absence by choice” (ABCh). The Big Five personality factors were found to be unrelated to objective uncertified absence records and unrelated to ABCo. Three of the Big Five were related to ABCh. Agreeableness was negatively related to ABCh whereas Extraversion and Openness demonstrated a positive correlation. It was concluded that the results should be viewed tentatively, but that this study may provide a useful framework for conceptualizing the association of personality with uncertified absence.
Resumo:
The number, diversity and restriction enzyme fragmentation patterns of plasmids harboured by 44 multidrug-resistant hospital-acquired methicillin-resistant Staphylococcus aureus (MR-HA-MRSA) isolates, two multidrug-resistant community-acquired MRSA (MR-CA-MRSA), 50 hospital-acquired MRSA (HA-MRSA) isolates (from the University Hospital Birmingham, NHS Trust, UK) and 34 community-acquired MRSA (CA-MRSA) isolates (from general practitioners in Birmingham, UK) were compared. In addition, pulsed-field gel electrophoresis (PFGE) type following SmaI chromosomal digest and SCCmec element type assignment were ascertained for each isolate. All MR-HA-MRSA and MR-CA-MRSA isolates possessed the type II SCCmec, harboured no plasmid DNA and belonged to one of five PFGE types. Forty-three out of 50 HA-MRSA isolates and all 34 CA-MRSA isolates possessed the type IV SCCmec and all but 10 of the type IV HA-MRSA isolates and nine CA-MRSA isolates carried one or two plasmids. The 19 non-multidrug-resistant isolates (NMR) that did not harbour plasmids were only resistant to methicillin whereas all the NMR isolates harbouring at least one plasmid were resistant to at least one additional antibiotic. We conclude that although plasmid carriage plays an important role in antibiotic resistance, especially in NMR-HA-MRSA and CA-MRSA, the multidrug resistance phenotype from HA-MRSA is not associated with increased plasmid carriage and indeed is characterised by an absence of plasmid DNA. © 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.
Resumo:
Using a new optical configuration free from the influence of photorefractive optical nonlinearity, we investigate the main characteristics of the spatial subharmonic K/2 excited in a Bi12SiO20 crystal by a light-intensity pattern with wave vector K and frequency O. It is shown that in a large region of intensity and applied electric field the optimum value O of the frequency corresponds to the conditions of parametric excitation of the weakly damped eigenmodes of the medium: the space-charge waves. The threshold and above-threshold characteristics of the subharmonic regime are in good agreement with the theory.