Effect of prepartum selenium treatment on uterine involution in the dairy cow

Selenium injections and oral vitamin E supplementation prepartum were related to: postpartum uterine involution (decrease in uterine size per unit time) and days to minimum uterine size in a 2 X 2 factorial design. Complete data were analyzed from 64 cows. Groups were selenium plus vitamin E, vitamin E, selenium, and control. Factors significantly affecting uterine size between 14 and 50 d postpartum were cow weight, days postpartum-linear, days postpartum-quadratic, day X metritis, and day X metritis X selenium treatment. Days to minimum uterine size were significantly less in cows with metritis and selenium treated when compared with cows with metritis and not selenium treated (32.9 vs. 35.8).     

The myelotoxicity of chloramphenicol: in vitro and in vivo studies: I. In vitro effects on cells in culture

1 Chloramphenicol is used extensively in non-industrialized countries for the treatment of life-threatening infections because it is cheap and effective, despite its known hemotoxicity and linkage to fatal aplastic anaemia. It is important to define the mechanism of toxicity so that means can be devised to ameliorate the toxic effects in order to produce safer usage. 2 Chloramphenicol, at concentrations from 5 mM to 2 mM initiated apoptosis in dividing cells from a monkey kidney-derived cell line and in haematopoietic progenitor cells from human neonatal cord blood. 3 Growth of progenitor cells was suppressed at concentrations of chloramphenicol which would be considered less than therapeutic during patient treatment. 4 These effects could be ameliorated in progenitor cells by co-culture with the antioxidant mercaptoethylamine and in monkey kidney cells by co-culture with vitamin C. 5 This is the first report of apoptosis in chloramphenicol toxicity and suggests a possible link between a metabolic event i.e. the production of free radicals; a morphological effect, apoptosis; and a clinical effect, bone marrow suppression and aplastic anaemia.     

Inhibition of reaper-induced apoptosis by interaction with inhibitor of apoptosis proteins (IAPs)

IAPs comprise a family of inhibitors of apoptosis found in viruses and animals. In vivo binding studies demonstrated that both baculovirus and Drosophila IAPs physically interact with an apoptosis-inducing protein of Drosophila, Reaper (RPR), through their baculovirus IAP repeat (BIR) region. Expression of IAPs blocked RPR-induced apoptosis and resulted in the accumulation of RPR in punctate perinuclear locations which coincided with IAP localization. When expressed alone, RPR rapidly disappeared from the cells undergoing RPR-induced apoptosis. Expression of P35, a caspase inhibitor, also blocked RPR-induced apoptosis and delayed RPR decline, but RPR remained cytoplasmic in its location. Mutational analysis of RPR demonstrated that caspases were not directly responsible for RPR disappearance. The physical interaction of IAPs with RPR provides a molecular mechanism for IAP inhibition of RPR's apoptotic activity.     

The role of policy instruments for promoting combined heat and power production with low CO2 emissions in district heating systems

Policy instruments clearly influence the choice of production technologies and fuels in large energy systems, including district heating networks. Current Swedish policy instruments aim at promoting the use of biofuel in district heating systems, and at promoting electric power generation from renewable energy sources. However, there is increasing pressure to harmonize energy policy instruments within the EU. In addition, natural gas based combined cycle technology has emerged as the technology of choice in the power generation sector in the EU. This study aims at exploring the role of policy instruments for promoting the use of low CO₂ emissions fuels in high performance combined heat and power systems in the district heating sector. The paper presents the results of a case study for a Swedish district heating network where new large size natural gas combined cycle (NGCC) combined heat and power (CHP) is being built. Given the aim of current Swedish energy policy, it is assumed that it could be of interest in the future to integrate a biofuel gasifier to the CHP plant and co‐fire the gasified biofuel in the gas turbine unit, thereby reducing usage of fossil fuel. The goals of the study are to evaluate which policy instruments promote construction of the planned NGCC CHP unit, the technical performance of an integrated biofuelled pressurized gasifier with or without dryer on plant site, and which combination of policy instruments promote integration of a biofuel gasifier to the planned CHP unit. The power plant simulation program GateCycle was used for plant performance evaluation. The results show that current Swedish energy policy instruments favour investing in the NGCC CHP unit. The corresponding cost of electricity (COE) from the NGCC CHP unit is estimated at 253 SEK MWh^?1, which is lower than the reference power price of 284 SEK MWh^?1. Investing in the NGCC CHP unit is also shown to be attractive if a CO₂ trading system is implemented. If the value of tradable emission permits (TEP) in such as system is 250 SEK tonne^?1, COE is 353 SEK MWh^?1 compared to the reference power price of 384 SEK MWh^?1. It is possible to integrate a pressurized biofuel gasifier to the NGCC CHP plant without any major re‐design of the combined cycle provided that the maximum degree of co‐firing is limited to 27–38% (energy basis) product gas, depending on the design of the gasifier system. There are many parameters that affect the economic performance of an integrated biofuel gasifier for product gas co‐firing of a NGCC CHP plant. The premium value of the co‐generated renewable electricity and the value of TEPs are very important parameters. Assuming a future CO₂ trading system with a TEP value of 250 SEK tonne^?1 and a premium value of renewable electricity of 200 SEK MWh^?1 COE from a CHP plant with an integrated biofuelled gasifier could be 336 SEK MWh^?1, which is lower than both the reference market electric power price and COE for the plant operating on natural gas alone. Copyright © 2005 John Wiley & Sons, Ltd.     

Evaluation of corrosion rate from polarisation curves not exhibiting a Tafel region

Evaluation of corrosion rate by Tafel extrapolation is often impossible, simply because an experimental polarisation curve does not exhibit linear Tafel regions. This paper shows how such curves for the Fe/H₂O/H⁺/O₂ corrosion system can be accurately deconstructed to furnish both kinetic and thermodynamic parameters for the anodic and cathodic reactions. The curved anodic branch (due to film formation) is then amenable to correction for IR voltage drop and the resulting Tafel slope and other parameters are then substituted in the Tafel equation to accurately determine i_corr. An alternative method to obtain the anodic Tafel slope has been used to validate the above approach. Polarisation curves describing the inhibition of mild steel in industrial cooling water were scanned/digitised from the literature.     

On the Ineffective Education of Decision Scientists

There is general agreement that the training of decision scientists during the past ten years has left much to be desired. This note presents nine rules relating to the fundamental reasons for the failure of training programs, along with suggestions for improving the present state of affairs.     

SUBURBANIZATION IN THE SEVENTIES: The “Push-Pull” Hypothesis Revisited

ABSTRACT: This article compares the effects of “push” and “pull” factors on decisions of white and black households without children to move from central cities to the suburbs. Unlike previous studies where the independent and dependent variables are aggregate characteristics of the metropolitan areas or individual suburbs, in this article the units are individual households and the variables characteristics of these households or the metropolitan area where they live. The data suggest that black and white decisions are affected by the same variables in the same way, and that blacks and whites are equally likely to move to the suburbs. We also find that both groups tend to move away from the central cities of metropolitan areas with large black populations and in which housing is relatively concentrated in the suburbs, consistent with both the “push” and “pull” hypotheses. However, neither racial group was apparently influenced by job suburbanization or central city crime rates, which is inconsistent with these hypotheses.     

Voltage controlled minority carrier collection—the exponentially retrograded photodiode

The large retarding field in an exponentially retrograded photodiode is shown to significantly reduce the base-generated photocurrent at low reverse-bias voltages. Increasing the reverse voltage on the diode reduces the length over which this retarding field is effective, thereby increasing the Photo-Transmission Coefficient of the diode. From avalanche breakdown considerations, the largest ratio of change in photocurrent caused by this effect is shown to be only a function of the resistivity and bulk-lifetime in the base of the diode. This voltage-controlled collection effect is observable only in diodes with high background resistivity (i.e. silicon > 25 Ω cm.). It is theoretically possible to obtain voltage-controlled collection ratios of better than 50:1 in, typically, a 10 V junction swing.

Experimental results compare well with theoretical models.     

Predicting River Travel Time from Hydraulic Characteristics

Predicting the effect of a pollutant spill on downstream water quality is primarily dependent on the water velocity, longitudinal mixing, and chemical∕physical reactions. Of these, velocity is the most important and difficult to predict. This paper provides guidance on extrapolating travel-time information from one within bank discharge to another. In many cases, a time series of discharge (such as provided by a U.S. Geological Survey stream gauge) will provide an excellent basis for this extrapolation. Otherwise, the accuracy of a travel-time extrapolation based on a resistance equation can be greatly improved by assuming the total flow area is composed of two parts, an active and an inactive area. For 60 reaches of 12 rivers with slopes greater than about 0.0002, travel times could be predicted to within about 10% by computing the active flow area using the Manning equation with n = 0.035 and assuming a constant inactive area for each reach. The predicted travel times were not very sensitive to the assumed values of bed slope or channel width.