Report on Crosby Creek erosion studies by models of drop structures located at junction of Crosby Creek and Canisteo River, Hornell, N. Y. : tests /

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Gap-junction communication between subtypes of direction-selective ganglion cells in the developing retina

The On-Off direction-selective ganglion cells (DSGCs) in the rabbit retina comprise four distinct subtypes that respond preferentially to image motion in four orthogonal directions; each subtype forms a regular territorial array, which is overlapped by the other three arrays. In this study, ganglion cells in the developing retina were injected with Neurobiotin, a gap-junction-permeable tracer, and the DSGCs were identified by their characteristic type 1 bistratified (BiS1) morphology. The complex patterns of tracer coupling shown by the BiSl ganglion cells changed systematically during the course of postnatal development. BiSl cells appear to be coupled together around the time of birth, but, over the next 10 days, BiSl cells decouple from each other, leading to the mature pattern in which only one subtype is coupled. At about postnatal day 5, before the ganglion cells become visually responsive, each of the BiSl cells commonly showed tracer coupling both to a regular array of neighboring BiSl cells, presumably destined to be DSGCs of the same subtype, and to a regular array of overlapping BiSl cells, presumably destined to be DSGCs of a different subtype. The gap-junction intercellular communication between subtypes of DSGCs with different preferred directions may play an important role in the differentiation of their synaptic connectivity, with respect to either the inputs that DSGCs receive from retinal interneurons or the outputs that DSGCs make to geniculate neurons. (C) 2004 Wiley-Liss, Inc.

Cyclopropane-1,1-dicarboxylate is a slow-, tight-binding inhibitor of rice ketol-acid reductoisomerase

Ketol-acid reductoisomerase (EC 1.1.1.86) catalyses the second reaction in the biosynthesis of the branched-chain amino acids. The reaction catalyzed consists of two stages, the first of which is an alkyl migration from one carbon atom to its neighbour. The likely transition state is therefore a cyclopropane derivative, and cyclopropane-1,1-dicarboxylate(CPD) has been reported to inhibit the Escherichia coli enzyme. In addition, this compound causes the accumulation of the substrate of ketol-acid reductoisomerase in plants. Here, we investigate the inhibition of the purified rice enzyme. The cDNA was cloned, and the recombinant protein was expressed in E. coli, purified and characterized kinetically. The purified enzyme is strongly inhibited by cyclopropane-1,1-dicarboxylate, with an inhibition constant of 90 nM. The inhibition is time-dependent and this is due to the low rate constants for formation (2.63 X 10(5) M-1 min(-1)) and dissociation (2.37 x 10(-2) min(-1)) of the enzyme-inhibitor complex. Other cyclopropane derivatives are much weaker inhibitors while dimethylmalonate is moderately effective. (c) 2004 Elsevier Ireland Ltd. All rights reserved.

Experimental investigation of interface states and photovoltaic effects on the scanning capacitance microscopy measurement for p-n junction dopant profiling

Controlled polishing procedures were used to produce both uniformly doped and p-n junction silicon samples with different interface state densities but identical oxide thicknesses. Using these samples, the effects of interface states on scanning capacitance microscopy (SCM) measurements could be singled out. SCM measurements on the junction samples were performed with and without illumination from the atomic force microscopy laser. Both the interface charges and the illumination were seen to affect the SCM signal near p-n junctions significantly. SCM p-n junction dopant profiling can be achieved by avoiding or correctly modeling these two factors in the experiment and in the simulation. (c) 2005 American Institute of Physics.

Family violence: Walking the tight rope between maternal alienation and child safety

Mothers are often alienated from their children when child abuse is suspected or confirmed, whether she is the primary abuser of the child or not. An abusive or violent partner often initiates the process of maternal alienation from children as a control mechanism. When the co-occurrence of maternal and child abuse is not recognised, nurses and health professionals risk further alienating a mother from her children, which can have detrimental effects in both the short and long term. Evidence shows that when mothers are supported and have the necessary resources there is a reduction in the violence and abuse she and her children experience; this occurs even in situations where the mother is the primary abuser of her children. The family-centred care philosophy, which is widely accepted as the best approach to nursing care for children and their families, creates tension for nurses caring for children who are the victims of abuse as this care generally occurs away from the context of the family. This fragmented approach to caring for abused children can inadvertently undermine the mother-child relationship and further contribute to maternal alienation. This paper discusses the complexity of family violence for nurses negotiating the 'tight rope' between the prime concern for the safety of children and further contributing to maternal alienation, within a New Zealand context. The premise that restoration of the mother-child relationship is paramount for the long-term wellbeing of both the children and the mother provides the basis for discussing implications for nursing practice.

Comparison of cultures from rectoanal-junction mucosal swabs and feces for detection of Escherichia coli 0157 in dairy heifers

Fecal culture for Escherichia coli 0157:H7 was compared to rectoanal mucosal swab (RAMS) culture in dairy heifers over a 1-year period. RAMS enrichment culture was as sensitive as fecal culture using immunomagnetic separation (IMS) (P = 0.98, as determined by a chi-square test). RAMS culture is less costly than fecal IMS culture and can yield quantitative data.

Distance measurement using the change in junction voltage across a laser diode due to the self-mixing effect

Conventional detection scheme for self-mixing sensors uses an integrated photodiode within the laser package to monitor the self mixing signal. This arrangement can be simplified by directly obtaining the self-mixing signals across the laser diode itself and omitting the photodiode. This work reports on a Vertical-Cavity Surface-Emitting Laser (VCSEL) based selfmixing sensor using the laser junction voltage to obtain the selfmixing signal. We show that the same information can be obtained with only minor changes to the extraction circuitry leading to potential cost saving with reductions in component costs and complexity and significant increase in bandwidth favoring high speed modulation. Experiments using both photo current and voltage detection were carried out and the results obtained show good agreement with the theory.

The effects of persistent articholinesterase action at the neuromuscular junction

The effects of organophosphorus compounds which form a rapidly-ageing complex with acetylcholinesterase (AChE) (e.g. pinacolyl S-(2- trimethylaminoethyl)methylphosphonothioate (BOS)) and hence exert a persistent anticholinesterase (anti-ChE) action have been compared with other compounds with a shorter time course of inhibition (e.g. ecothiopate iodide (ECO)). Although the inhibition of AChE produced by BOS lasted longer than that seen with ECO, the time course of the myopathy appeared very similar. BOS also possessed a number of properties which have been seen with other anti-ChEs. BOS and ECO produced significant increases in neuromuscular "jitter" 5 days after injection, not only in the diaphragm but also in the soleus and extensor digitorum longus muscles. Increases in "jitter" produced by ECO could be prevented by pyridostigmine prophylaxis or rapid treatment with pyridine-2- aldoxime methiodide. Some protection from the BOS-induced increases in "jitter" could be gained by repeated treatment with pyridine-2-aldoxime methiodide, an effect which could not be accounted for simply by enzyme reactivation. From experiments performed in Rej 129 mice it was determined that increases in "jitter", although demonstrated in some dystrophic muscles, could not be used as an early diagnostic tool. Because sequalae of inhibition were present some time after intoxication, by which time AChE appeared biochemically normal, experiments were performed to investigate inactivation of physiologically important AChE. The time course of extracellular MEPPs was utilised as an indicator of physiologically important AChE and compared with the AChE activity measured by the technique of Ellman et al. (1961). It was concluded that the degree of persistence of anti-ChE action was unimportant for the induction of myopathy with a time course of 3-24 hours, but had some importance in events of longer duration.