Why do fish strand? An analysis of ten years of flow reduction monitoring data from the Columbia and Kootenay rivers,Canada

Stranding of fish due to flow reductions has been documented in the near shore of the Columbia and Kootenay Rivers, Canada, and can result in sub‐lethal or lethal effects on fish. Ten years (1999–2009) of monitoring data have been collected at sites below two hydro‐electric dams (Hugh‐L‐Keenleyside and Brilliant Dam) following flow reductions. A generalized linear mixed effects model analysed the probability of a stranding event in relation to environmental and operational variables including the rate of change in the water levels, the duration of shoreline inundation prior to a reduction (wetted history), the river stage, the magnitude of the reduction, distance downstream from the dam, time of day, day of year (season) and whether a site had been physically altered to mitigate stranding. The results demonstrated statistically significant effects on stranding risk from minimum river stage, day of the year and whether a site had been physically re‐contoured. The combination of investigated factors giving the highest probability of stranding was a large magnitude reduction completed in the afternoon in midsummer, at low water levels when the near shore had been inundated for a long period. This research is significant in its approach to assessing years of ecosystem scale monitoring data and using the modelling results to determine ways for these findings to be applied in regulated river management to minimize fish stranding. It also highlighted data gaps that require addressing and provides ecosystem scale results to compare with stranding studies carried out in mesocosms. © 2014 The Authors. River Research and Applications published by John Wiley & Sons Ltd.     

Settlement due to Diaphragm Wall Construction in Reclaimed Land in Hong Kong

For more than two decades diaphragm walling has become commonly used for the construction of deep excavations in Hong Kong. For example, 13 of the main excavations for the Island Line of the Mass Transit Railway (MTR), completed in 1986, adopted diaphragm walls as the principal support to the excavation. Diaphragm walls were particularly appropriate to the MTR construction in over-crowded urban Hong Kong, limiting adverse effects on surrounding buildings and allowing top-down construction methods, thus reducing programming time. Settlement was predicted for buildings on deep foundations (piles), adjacent to deep excavations, and the actual settlement was monitored by conventional surveying techniques. The results indicate that settlement due to diaphragm walling is generally substantial and that preconstruction activities such as ground treatment, drilling, and preboring for wall panels, must be taken into account in any settlement predictions.     

The effects of group expectations and self-esteem upon self-evaluation.

This study explores the effect of a specific level of achievement upon an individual's evaluations of his performance when the achievement is relative to an aspiration level set by a group and to the member's stabilized expectations about himself as represented by his self-esteem. Ss were assigned to one of 4 conditions, composed of the combinations of high and low group expectations and relevance and non-relevance of task to the purposes of the group. Half of the Ss within each experimental condition were allowed to succeed and the other half made to fail. Several specific hypotheses within this framework were tested. "The group's expectations appear to have been more potent as a scale of reference than the individual's self-esteem in determining his evaluation of his performance. When the influence of the group was weakest (task was non-relevant) persons high in self-esteem… differed in the way they evaluated their performance. When the influence of the group was strongest (task was relevant) there was no difference in the way that persons high or low in self-esteem rated their achievement." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Energetic Control of Redox-Active Polymers toward Safe Organic Bioelectronic Materials

Avoiding faradaic side reactions during the operation of electrochemical devices is important to enhance the device stability, to achieve low power consumption, and to prevent the formation of reactive side-products. This is particularly important for bioelectronic devices, which are designed to operate in biological systems. While redox-active materials based on conducting and semiconducting polymers represent an exciting class of materials for bioelectronic devices, they are susceptible to electrochemical side-reactions with molecular oxygen during device operation. Here, electrochemical side reactions with molecular oxygen are shown to occur during organic electrochemical transistor (OECT) operation using high-performance, state-of-the-art OECT materials. Depending on the choice of the active material, such reactions yield hydrogen peroxide (H₂O₂), a reactive side-product, which may be harmful to the local biological environment and may also accelerate device degradation. A design strategy is reported for the development of redox-active organic semiconductors based on donor–acceptor copolymers that prevents the formation of H₂O₂ during device operation. This study elucidates the previously overlooked side-reactions between redox-active conjugated polymers and molecular oxygen in electrochemical devices for bioelectronics, which is critical for the operation of electrolyte-gated devices in application-relevant environments.     

Review of follow-up and follow-back studies of childhood hyperactivity.

The outcome for children diagnosed as hyperactive is viewed as an important perspective in validating the disorder. Accordingly, a review of 17 follow-up and 7 follow-back studies is presented that assesses the available evidence relating to this issue. In follow-back studies, Ss were chosen and assessed on the basis of past information (i.e., a diagnosis of hyperactivity contained in medical records) that they were hyperactive in childhood. Methodological problems are identified and discussed. In particular, it is noted that all of the follow-up studies failed to use psychiatric controls; this makes it difficult to draw conclusions about the diagnostic validity of the concept of hyperactivity. Four of the follow-back studies did use psychiatric controls, but conclusions are limited by the atypical nature of their S groups. It has been demonstrated, however, that hyperactives in late adolescence and early adulthood, as compared with normal controls, experience difficulties in many areas of social functioning and personal well-being. (71 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An electron microscope study of Bacteroides nodusus: ultrastructure of organisms from primary isolates and different colony types

Various fractions of alcoholic extract of Pimelea trichostachya were prepared and three of these were compared in terms of (a) ability to produce sustained contraction of spiral muscle of bovine pulmonary vein in vitro, (b) LD50 values in mice by intraperitoneal injection and (c) acute toxicity by intravenous injection into calves. Good agreement was observed between activity of the fractions in all three systems, thus providing further evidence for the role of pulmonary venous hypertension in the pathogenesis of at least part of the syndrome of Pimelea poisoning in the bovine. The most toxic of the fractions was shown by chronic intoxication of a calf to be capable of producing most of the features of the natural disease.     

A tagged photon spectrometer for use with the mainz 180 MeV microtron

This paper describes a photon tagging system which has been installed on the 180 MeV electron microtron at the Institut für Kernphysik in Mainz for use in experiments on photonuclear reactions at intermediate energies. The system enables bremsstrahlung produced photons in the energy range 80–174 MeV to be tagged at rates up to 5×10⁷ s^?1.     

Understanding the Crystal Packing and Organic Thin‐Film Transistor Performance in Isomeric Guest–Host Systems

In order to understand how additives influence the structure and electrical properties of active layers in thin‐film devices, a compositionally identical but structurally different guest–host system based on the syn and anti isomers of triethylsilylethynyl anthradithiophene (TES ADT) is systematically explored. The mobility of organic thin‐film transistors (OTFTs) comprising anti TES ADT drops with the addition of only 0.01% of the syn isomer and is pinned at the mobility of OTFTs having pure syn isomer after the addition of only 10% of the isomer. As the syn isomer fraction increases, intermolecular repulsion increases, resulting in a decrease in the unit‐cell density and concomitant disordering of the charge‐transport pathway. This molecular disorder leads to an increase in charge trapping, causing the mobility of OTFTs to drop with increasing syn‐isomer concentration. Since charge transport is sensitive to even minute fractions of molecular disorder, this work emphasizes the importance of prioritizing structural compatibility when choosing material pairs for guest–host systems.     

Redox‐Stability of Alkoxy‐BDT Copolymers and their Use for Organic Bioelectronic Devices

Organic semiconductors can be employed as the active layer in accumulation mode organic electrochemical transistors (OECTs), where redox stability in aqueous electrolytes is important for long‐term recordings of biological events. It is observed that alkoxy‐benzo[1,2‐b:4,5‐b′]dithiophene (BDT) copolymers can be extremely unstable when they are oxidized in aqueous solutions. The redox stability of these copolymers can be improved by molecular design of the copolymer where it is observed that the electron rich comonomer 3,3′‐dimethoxy‐2,2′‐bithiophene (MeOT2) lowers the oxidation potential and also stabilizes positive charges through delocalization and resonance effects. For copolymers where the comonomers do not have the same ability to stabilize positive charges, irreversible redox reactions are observed with the formation of quinone structures, being detrimental to performance of the materials in OECTs. Charge distribution along the copolymer from density functional theory calculations is seen to be an important factor in the stability of the charged copolymer. As a result of the stabilizing effect of the comonomer, a highly stable OECT performance is observed with transconductances in the mS range. The analysis of the decomposition pathway also raises questions about the general stability of the alkoxy‐BDT unit, which is heavily used in donor–acceptor copolymers in the field of photovoltaics.