New members of the chiral pool:  -hydroxypiperidine carboxylates from bakers' yeast reductions of the corresponding keto-esters.

. Knight, David W.; Lewis, Neil; Share, Andrew C.; Haigh, David. Chem. Dept., Univ. of Nottingham, Nottingham, UK. Tetrahedron: Asymmetry (1993), 4(4), 625-8. CODEN: TASYE3 ISSN: 0957-4166. Journal written in English. CAN 120:54423 AN 1994:54423 CAPLUS (Copyright (C) 2009 ACS on SciFinder (R)) Abstract Redn. of the keto-piperidinecarboxylates I and II with fermenting bakers' yeast produced the corresponding hydroxy-esters III and IV in good yields with >99% diastereomeric excess and >93% enantiomeric excess in both cases.

 -Hydroxypiperidinecarboxylates: additions to the chiral pool from bakers' yeast reductions of  -ketopiperidinecarboxylates.

Knight, David W.; Lewis, Neil; Share, Andrew C.; Haigh, David. Chemistry Department, University of Nottingham, Nottingham, UK. Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1998), (22), 3673-3684. Publisher: Royal Society of Chemistry, CODEN: JCPRB4 ISSN: 0300-922X. Journal written in English. CAN 130:153545 AN 1998:715806 CAPLUS (Copyright (C) 2009 ACS on SciFinder (R)) Abstract Redn. of the piperidine keto esters, e.g., I, using fermenting bakers' yeast provides high yields of the corresponding hydroxy esters, e.g., II, exclusively as the cis-diastereoisomers and with good levels (?80%) of enantiomeric enrichment. The relative stereochemistries of the products were deduced from NMR data while the abs. configurations were detd. by degrdn. to known piperidinemethanol derivs. or, in the case of hydroxy ester III, by homologation to (R)-3-quinuclidinol IV.

Asymmetric rhodium carbenoid insertion into the Si-H bond.

Buck, Richard T.; Doyle, Michael P.; Drysdale, Martin J.; Ferris, Leigh; Forbes, David C.; Haigh, David; Moody, Christopher J.; Pearson, Neil D.; Zhou, Qi-Lin. Dep. Chemistry, Loughborough Univ., Loughborough, Leicestershire, UK. Tetrahedron Letters (1996), 37(42), 7631-7634. Publisher: Elsevier, CODEN: TELEAY ISSN: 0040-4039. Journal written in English. CAN 125:328854 AN 1996:644681 CAPLUS (Copyright (C) 2009 ACS on SciFinder (R)) Abstract Decompn. of Me 2-diazophenylacetate in the presence of dimethylphenylsilane and a chiral dirhodium(II) catalyst results in Si-H insertion of the intermediate carbenoid to give PhCH(SiMe2Ph)CO2Me with varying degrees of enantioselectivity (up to 47% ee; 47% using (S)-Rh2L4, LH = I).

Endothelin 1 Stimulates Ca2+-Sparks and Oscillations in Retinal Arteriolar Myocytes via IP3R and RyR-Dependent Ca2+ Release

PURPOSE:
To investigate endothelin 1 (Et1)-dependent Ca(2+)-signaling at the cellular and subcellular levels in retinal arteriolar myocytes.
METHODS:
Et1 responses were imaged from Fluo-4-loaded smooth muscle in isolated segments of rat retinal arteriole using confocal laser microscopy.
RESULTS:
Basal [Ca(2+)](i), subcellular Ca(2+)-sparks, and cellular Ca(2+)-oscillations were all increased during exposure to Et1 (10 nM). Ca(2+)-spark frequency was also increased by 90% by 10 nM Et1. The increase in oscillation frequency was concentration dependent and was inhibited by the EtA receptor (Et(A)R) blocker BQ123 but not by the EtB receptor antagonist BQ788. Stimulation of Ca(2+)-oscillations by Et1 was inhibited by a phospholipase C blocker (U73122; 10 µM), two inhibitors of inositol 1,4,5-trisphosphate receptors (IP(3)Rs), xestospongin C (10 µM), 2-aminoethoxydiphenyl borate (100 µM), and tetracaine (100 µM), a blocker of ryanodine receptors (RyRs).
CONCLUSIONS:
Et1 stimulates Ca(2+)-sparks and oscillations through Et(A)Rs. The underlying mechanism involves the activation of phospholipase C and both IP(3)Rs and RyRs, suggesting crosstalk between these Ca(2+)-release channels. These findings suggest that phasic Ca(2+)-oscillations play an important role in the smooth muscle response to Et1 within the retinal microvasculature and support an excitatory, proconstrictor role for Ca(2+)-sparks in these vessels.

Primary science teacher confidence revisited: ten years on

Background

The pitfall with PIT tags: Marking freshwater bivalves for translocation induces short-term behavioural costs

Tagging animals is frequently employed in ecological studies to monitor individual behaviour, for example postrelease survival and dispersal of captive-bred animals used in conservation programmes. While the majority of studies focus on the efficacy of tags in facilitating the relocation and identification of individuals, few assess the direct effects of tagging in biasing animal behaviour. We used an experimental approach with a control to differentiate the effects of handling and tagging captive-bred juvenile freshwater pearl mussels, Margaritifera margaritifera, prior to release into the wild. Marking individuals with passive integrated transponder (PIT) tags significantly decreased their burrowing rate and, therefore, increased the time taken to burrow into the substrate. This effect was contributed to, in part, by the detrimental impacts of handling, which also significantly affected activity, burrowing ability and the time taken for each individual to emerge and start probing the substrate. Disturbance during handling and tagging may lead to indirect mortality after release by increasing the risk of predation or dislodgement during flooding, thereby potentially compromising any conservation strategy contingent on population supplementation or reintroduction. This is the first study to demonstrate that handling and PIT tagging has a detrimental impact on invertebrate behaviour. Moreover, our results provide useful information that will inform freshwater bivalve conservation strategies.

USE OF RETRODIRECTIVE ARRAY PHASE CONJUGATION CIRCUITRY FOR NEAR- AND FAR-FIELD POSITION ANGLE OF ARRIVAL DETECTION

In this article, we present position indication functionality as obtained by using a retrodirective array, thereby allowing location information extraction of the position of the remote transmitter with which the retrodirective array is cooperating. This is carried out using straightforward circuitry with no requirement for complex angle of arrival algorithms, thereby giving a result in real time enabling tracking of fast moving transmitters. We show using a 10 x element retrodirective array, operating at 2.4 GHz that accuracies of far-field angle of arrival of within +/- 1 degrees over the arrays +/- 30 degrees azimuth field of view are possible. While in the near-field for angles of arrival of +/- 10 degrees it is possible to extract the position of a dipole source down to a resolution of 032 lambda. (C) 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1031-1034, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25097

Bit error rate performance enhancement of a retrodirective array over a conventional fixed beam array in a dynamic multipath environment

In this paper, we provide experimental evidence to show that enhanced bit error rate (BER) performance is possible using a retrodirective array operating in a dynamically varying multipath environment. The operation of such a system will be compared to that obtained by a conventional nonretrodirective array. The ability of the array to recover amplitude shift keyed encoded data transmitted from a remote location whose position is not known a priori is described. In addition, its ability to retransmit data inserted at the retrodirective array back to a spatially remote beacon location whose position is also not known beforehand is also demonstrated. Comparison with an equivalent conventional fixed beam antenna array utilizing an identical radiating aperture arrangement to that of the retrodirective array are given. These show that the retrodirective array can effectively exploit the presence of time varying multipath in order to give significant reductions in BER over what can be otherwise achieved. Additionally, the retrodirective system is shown to be able to deliver low BER regardless of whether line of sight is present or absent.

Active Phase Conjugating Lens With Sub-Wavelength Resolution Capability

Experimental results are presented for the focusing capability of an active phase conjugating lens for a single and a dipole source pair and these are compared with predictions. In addition for a single source we illustrate the ability of the lens to project a null at the lens focus instead of a peak. A scheme is also presented such that when a source or pair of sources is imaged through an identical pair of passive scatterers located symmetrically about the lens that imaging with sub-wavelength resolution is possible. The rationale for the operation of the lens and aberrations observed due to its finite array size is discussed and is supported throughout by means of numerical simulation.

Retrodirective Array Performance in the Presence of Near Field Obstructions

We investigate the situation where there are obstructing elements present in the near field of a retrodirective array. We describe three scattering cases, (1) by an array of straight wires, (2) by low loss medium density fibre board partially obscuring the array, and (3) by concrete blocks, totally and then partially obscuring the array. For all scenarios retrodirective action was shown to be able to provide various degrees of automatic compensation for loss in gain relative to that which would have occurred for a conventional (non-retrodirective) array in the presence of the same scattering screens. Gain improvements of up to 10 dB were observed when the retrodirective array was used. In addition we show how the induced variation of received and re-transmited amplitudes across the array, caused by the scattering screens, is the principle mechanism causing deterioration of the retrodirective arrays monostatic response.