A physiological and genetic analysis of growth characteristics in Hordeum spontaneum

The aim of this project was to determine to what extent physiological, morphological and chemical growth characteristics are genetically linked and/or caused by common factors. First, 84 accessions of H. spontaneum from different habitats in Israel were screened for their variation in growth traits. A cross was made between contrasting genotypes and the F3 offspring were grown under close to optimal conditions and analysed for their growth characteristics. A map was constructed using AFLP markers. On chromosome 1 two QTLs for relative growth rate and specific leaf area were found at the same location. On chromosome 4 two QTLs for photosynthesis per unit leaf area and stomatal conductance were found at the same position. These traits are probably genetically linked or controlled by a common factor

Nitrite Accumulation by denitrifiers isolated from fluidized Bed Reactors operated in an Aquaculture Unit

In fluidized bed rnactors, applled for nitrate removal in an aquaculture unit, denitrificatlon of nitrate was found to result in an accumulation of nitrite. Isolation of denltrifylng bacteria from these reactors revealed that most of these isolates produced nitrite from nitrate under controlled laboratory. conditions. Two of the isolates, one with accumulated nitrite while respiring on nitrate, and the other not, were subject to further studies. It was found that nitrite accumulation in one of these isolates could be adequately explained by differences in the relative rates of nitrate and nitrite reduction. Inhibiting concentrations of nitrite were lower for the isolate which did not accumulate nitrite. Incubation of the nitrite-accumulating isolate with different carbon sources resulted ln differences in the relative nitrite accumulation (as compared with the runount of nitrate reduced

Perceived Organizational Support and Knowledge Sharing: Employees’ Self-Construal Matters

HR professionals are expected to become more involved in knowledge management and facilitate knowledge sharing among employees in the knowledge economy. In this study, we investigated the relationship between perceived organizational support and knowledge sharing by taking account of employees’ interdependent and independent self-construal. Our hypotheses were examined using a 2-wave survey data-set from 145 teachers working at 4 Dutch vocational education and training schools. The results showed that perceived organizational support was positively related to knowledge sharing for employees either with a high interdependent self or with a low independent self. However, this positive relationship disappeared for employees either with a low interdependent self or with a high independent self. Overall, the moderating effect of self-construal revealed a new avenue towards a better understanding of the relationship between organizational support and employees’ knowledge sharing. It provided a tentative answer to the question of why organizational support does not often succeed in motivating employees to share their knowledge in the workplace

Eye torsion associated with disparity-induced vertical vergence in humans

Recently, Enright described an unexpected association between disparity-induced vertical vergence and cycloversion (conjugate eye torsion) [Enright (1992)Vision Research, 415, 279]. The present experiments were performed to verify these findings and investigate the nature of this association. We presented subjects with a dichoptic image of concentric circles in which a step in vertical disparity of 1 deg was introduced. After 4 sec the disparity was eliminated. Eye movements were measured with scierai coils. We confirmed Enright's findings in that a left-over right vertical vergence was associated with levo-cycloversion (upper poles towards left shoulder) and vice versa. The size of the cycloversion and the vertical vergence were in the same range. In addition we found that part of the cycloversion response was in the form of a torsional nystagmus and that the relative contribution of the left and right eyes was independent of the horizontal gaze angle. These additional findings are in conflict with the hypothesis, offered by Enright, that the association is caused by a bilateral activity of the superior oblique muscles

How to assess the existence of competing strategies in cognitive tasks: a primer on the fixed-point property

When multiple strategies can be used to solve a type of problem, the observed response time distributions are often mixtures of multiple underlying base distributions each representing one of these strategies. For the case of two possible strategies, the observed response time distributions obey the fixed-point property. That is, there exists one reaction time that has the same probability of being observed irrespective of the actual mixture proportion of each strategy. In this paper we discuss how to compute this fixed-point, and how to statistically assess the probability that indeed the observed response times are generated by two competing strategies. Accompanying this paper is a free R package that can be used to compute and test the presence or absence of the fixed-point property in response time data, allowing for easy to use tests of strategic behavior

Oscillatory multiplexing of neural population codes for interval timing and working memory

Interval timing and working memory are critical components of cognition that are supported by neural oscillations in prefrontal-striatal-hippocampal circuits. In this review, the properties of interval timing and working memory are explored in terms of behavioral, anatomical, pharmacological, and neurophysiological findings. We then describe the various neurobiological theories that have been developed to explain these cognitive processes - largely independent of each other. Following this, a coupled excitatory - inhibitory oscillation (EIO) model of temporal processing is proposed to address the shared oscillatory properties of interval timing and working memory. Using this integrative approach, we describe a hybrid model explaining how interval timing and working memory can originate from the same oscillatory processes, but differ in terms of which dimension of the neural oscillation is utilized for the extraction of item, temporal order, and duration information. This extension of the striatal beat-frequency (SBF) model of interval timing (Matell and Meck, 2000, 2004) is based on prefrontal-striatal-hippocampal circuit dynamics and has direct relevance to the pathophysiological distortions observed in time perception and working memory in a variety of psychiatric and neurological conditions. (C) 2014 Elsevier Ltd. All rights reserved.</p