Long‐term simulations of the dynamics of trout populations on river reaches bypassed by hydroelectric installations—analysis of the impact of different hydrological scenarios

Changes in a brown trout (Salmo trutta L.) population result from interaction among various mechanisms which are dependent on environmental conditions and biotic processes. In reaches influenced by the presence of dams, the instream flow in the bypassed section is not the only parameter which affects the population. Flood episodes, the general connectivity of the bypassed section, and the characteristics of the substrate which define the availability and quality of spawning grounds may also have a crucial impact. The design and fine‐tuning of tools which take environmental parameters into account can improve our understanding of the dynamics of such influenced populations. In this perspective, a deterministic model (MODYPOP) has been developed in an attempt to integrate all these factors and to test the effect of different long‐term scenarios of influenced flow regimes on the structure of trout populations. MODYPOP was applied to three populations and three reaches (on the Roizonne, Neste d'Aure and Lignon du Forez rivers in France). For each stream, experiments were carried out on a bypassed section downstream of a hydropower station, before and after an increase in the minimum instream flow due to relicensing. These experiments allowed integrating into MODYPOP local phenomena (impact of flood episodes, impact of flushing, impact of downstream migration of juveniles and adults) affecting the populations during the study period and then calibrating them. To estimate the change in the population due to the increase in minimum instream flow, different long‐term simulations were run, selecting discharge patterns at random. These scenarios help to evaluate the time required for the population to return to a range close to habitat saturation after an improvement in the hydraulic habitat or following a flood event. These applications have enabled determining the relative importance of changes in population density due to different types of events. Copyright © 2008 John Wiley & Sons, Ltd.     

The generality of abundance‐environment relationships in microhabitats: A comment on Lancaster and Downes (2009)

We comment on a criticism of hydraulic preference models and instream habitat models. We provide evidence of the generality of many hydraulic preference models, which supports their use in instream habitat modelling even if the detailed mechanistic causes of the observed preferences are not fully known. We also reply to the assertion that preference models are not based on sound ecological theory. We identify unbalanced use of available knowledge and point out limitations relating to too detailed biological focusses. Copyright © 2010 John Wiley & Sons, Ltd.     

A remotely controlled coaxial switch for impedance standard calibration

A switch which permits the connection, in sequence, of a couple of four-terminal-pair impedance standards to an automatic RLC bridge, is presented. The purpose of the switch is to automate the process of impedance calibration by 1:1 substitution. The switch is capable of engaging four coaxial lines at a time (switching both the internal conductor and the screen of each line); the electrical contacts are British Post Office MUSA connector. The switch, in the closed position, adds 2 m/spl Omega/ of resistance to each coaxial line in the electrical path. The switch is moved by pneumatic actuators to avoid any electrical interference, and is remotely controlled via RS-232 interface. Measurement examples are shown.     

A traceable technique to calibrate dc current shunts and resistors in the range from 10 μΩ to 10 mΩ

A traceable to dc resistance and dc voltage National Standards measurement technique to calibrate dc current shunts and resistors in the range from 10 μΩ to 10 mΩ has been developed at National Institute of Metrological Research (INRIM) in addition to the primary reference system for low value resistors calibration. This technique is applicable in secondary and industrial metrological laboratories. It is based on a volt-amperometric method, to compare an unknown shunt with a standard one in 1:1 or 1:10 ratios. In the setup are involved: a dc current calibrator and a current generator to supply currents respectively up to 100 A and up to 1200 A, with a switch to reverse the current, two 7 1/2 digit nanovoltmeters (nVs) for the acquisition of the voltage on the standard and under calibration shunts and two Tinsley 100 μΩ and 1 mΩ standard shunts kept in mineral oil and with a cooling system. An optional variation in the procedure that can reduce the measurement uncertainties is discussed. The 2σ relative capabilities of the technique span from 6.0 × 10⁻⁶to 4.6 × 10⁻⁴. Compatibility results with the INRIM reference measurement system for low value resistors calibration are also given.     

Diabetes and autoimmune diseases. I

An account is given of the clinical and serological associations between diabetes and autoimmune diseases, especially those between diabetes and antihyperoglobulin, antithyroid, anti-intrinsic factor, anticorticoadrenal cell, and anti-nucleic acid autoantibodies. Body fluid antipancreas autoimmunity is examined from various standpoints relating to antipancrease cell antibodies (ICA), autoantibodies against glucagon-secreting cells (ECA) and somatostatin-secreting cells (SCA), and anti-islet cell surface antibodies (McLaren and Lernmark antibodies). Particular attention is directed to ICAs, since these have supplied the background for the recent division of type I diabetes into Ia viral and Ib autoimmune. Stress is laid on both the soundness and the problems forming part of ICAs, since their actual pathogenetic role (cytoplasmic markers?) still has to be determined, even though their persistent and significant association with autoimmune polyendocrinopathies is certain.     

Triple dose of gadolinium-DTPA and delayed MRI in patients with benign multiple sclerosis

OBJECTIVES: To evaluate whether a triple dose of gadolinium-DTPA (Gd-DTPA) or delayed MRI increase the number, size, and conspicuousness of enhancing lesions in patients with benign multiple sclerosis. METHODS: T1 weighted brain MRI was carried out on 20 patients with benign multiple sclerosis (expanded disability status scale < 3 with a disease duration > 10 years) in two sessions. In the first session, one scan was obtained before and two scans five to seven minutes and 20-30 minutes after the injection of 0.1 mmol/kg Gd-DTPA (standard dose). In the second session, six to 24 hours later, the same procedure was repeated with 0.3 mmol/kg Gd-DTPA (triple dose). RESULTS: Nine enhancing lesions were found in seven patients (35%) using the standard dose of Gd-DTPA. The numbers of enhancing lesions increased to 13 (P = 0.03) and the number of patients with such lesions to eight (40%) on the delayed standard dose scans. On the early triple dose scans, we found 19 enhancing lesions in 10 patients (50%). The number of enhancing lesions was significantly higher (P = 0.01) than that obtained with the early standard dose. The number of enhancing lesions was 18 and the number of "active" patients 11 (55%) on the delayed triple dose scans. The enhancing areas increased progressively from the early standard dose scans to the delayed triple dose scans. The contrast ratios of the lesions detected in early standard dose scans was lower than those of lesions present in the early (P = 0.01) and delayed (P = 0.04) triple dose scans. CONCLUSIONS: More enhancing lesions were detected in patients with benign multiple sclerosis with both delay of MRI and the use of triple dose of Gd-DTPA suggesting that the amount of inflammation in the lesions of such patients is mild and heterogeneous.