Going, going, gone? Plant species extinction in the 21st century

Prospects for halting it or even slowing its rate are bleak, but perhaps not hopeless.     

Economics of food irradiation

This article examines the cost competitiveness of the food irradiation process. An analysis of the principal factors — the product, physical plant, irradiation source, and financing — that impact on cost is made. Equations are developed and used to calculate the size of the source for planned product throughput, efficiency factors, power requirements, and operating costs of sources, radionuclides, and accelerators. Methods of financing and capital investment are discussed. A series of tables show cost breakdowns of sources, buildings, equipment, and essential support facilities for both a cobalt‐60 and a 10‐MeV electron accelerator facility. Additional tables present irradiation costs as functions of a number of parameters — power input, source size, dose, and hours of annual operation. The use of the numbers in the tables are explained by examples of calculations of the irradiation costs for disinfestation of grains and radicidation of feed.     

Depolarization shifts the voltage dependence of cardiac sodium channel and calcium channel gating charge movements

In cardiac ventricular myocytes, membrane depolarization leads to the inactivation of the Na channel and Ca channel ionic currents. The inactivation of the ionic currents has been associated with a reduction of the gating charge movement ("immobilization") which governs the activation of Na channels and Ca channels. The nature of the apparent "immobilization" of the charge movement following depolarization was explored in embryonic chick ventricular myocytes using voltage protocols applied from depolarized holding potentials. It was found that although all of the charge was mobile following inactivation, the voltage dependence of its movement was shifted to more negative potentials. In addition, the shift in the distribution of the Na channel charge could be differentiated from that of the Ca channel charge on the basis of kinetic as well as steady-state criteria. These results suggest that the voltage-dependent activation of Na channel and Ca channel charge movements leads to conformational changes and charge rearrangements that differentially bias the movements of these voltage sensors, and concomitantly produce channel inactivation.     

Cows for fear: is BSE a threat to human health? Bovine spongiform encephalopathy

In 1996, a new variant of Creutzfeldt-Jakob disease (vCJD)-a disease that causes lack of coordination, muscle twitching or jerking, dementia, and, eventually, death-suddenly appeared in Great Britain. It is believed that the victims contracted the disease from eating the beef of cattle stricken with bovine spongiform encephalopathy (BSE), or mad cow disease. As of December 1997, at least 25 people in the United Kingdom and France have contracted vCJD.     

Illustrative Benchmarking Rework and Rework Costs in Swedish Construction Industry

Following several studies investigating the causes of construction rework among some projects in the Swedish construction industry, we conducted this study in cooperation with R&D West, a group of construction companies in Sweden, to measure the costs of rework in construction projects. Rework has become an endemic feature of the procurement process in construction that invariably leads to time and cost overruns in projects. Thus, in order to improve the performance of projects, it is necessary to identify the causes and costs of construction rework. The research presented in this paper identifies, analyzes, and discusses the causes, magnitudes, and costs of rework experienced in seven Swedish construction projects. The findings revealed that the costs of rework for the case study projects were 4.4% of the construction values of the observation period, and the time needed to correct them was 7.1% of the total work time. The construction errors that generated rework were further analyzed according to their origins, types, and positions, causes of construction rework were identified and discussed, and preventive actions were suggested.     

Bioaerosols from the land application of biosolids in the desert southwest USA.

This study evaluated bioaerosol emissions during land application of Class B biosolids in and around Tucson, Arizona, to aid in developing models of the fate and transport of bioaerosols generated from the land application of biosolids. Samples were collected for 20 min at distances between 2 m and 20 m downwind of point sources, using an SKC BioSampler impinger. A total of six samples were collected per sampling event, which consisted of a biosolid spray applicator applying liquid biosolids to a cotton field. Each application represented one exposure. Samples were collected in deionised water amended with peptone and antifoam agent. Ambient weather conditions were also monitored every 10 min following initiation of sampling. Concurrently with downwind samples, background (ambient) air samples were collected to compensate for any ambient airborne microorganisms. In addition, biosolids samples were collected for analysis of target indicator and pathogenic organisms. Soil samples were also collected and analysed. Significant numbers of heterotrophic plate count (HPC) bacteria were found in air samples collected during the biosolid application process. These could have arisen from soil particles being aerosolised during the land application process. Aerosolised soil may contribute significantly to the amount of aerosolised microorganisms. Soil particles may be able to more readily aerosolise, due to their low density, small particle size and low mass. Aerosolised HPC bacteria found during biosolids land application were similar to those found during normal tractor operation on non-biosolids applied fields. Coliforms and coliphages were not routinely detected even though they were found to be present in the biosolids at relatively high concentrations, 10(6) and 10(4)/g (dry weight) of biosolids respectively. This could be due to the die-off rate of aerosolised Gram-negative bacteria or sorption to the solid portion of the biosolids. Low numbers of aerosolised coliphages may likewise be due to sorption phenomena. We theorise that only organisms in the aqueous phase of the biosolids were available to desorb and be aerosolised. Animal viruses, which were not detected in the biosolids, were likewise not detected in the aerosol samples. Clostridium perfringens was detected in only a small percent of aerosol samples although it was detected during all weather conditions; other microorganisms were detected during more favourable environmental conditions (relative humidity >10%). Despite the fact that many of these organisms were present in the biosolids at significant concentrations, their presence in bioaerosols generated during the land application of biosolids was limited to only a small percentage of samples. Bacteria as well as viruses may sorb to biosolids, which contain a high percentage of organic matter, and desorption during land application of biosolids may not readily take place; therefore, these microorganisms may not be readily aerosolised.