Production Rate

We analyze the pair production of charged particles in two-dimensional Anti-de Sitter space (AdS_2) with a constant, uniform electric field. We compute the production rate both at a semi-classical level, viewing Schwinger pair production as a tunneling event, and at the full quantum level, by extracting the imaginary part of the one-loop amplitude. In contrast to the usual Schwinger pair production in flat space, pair production in AdS_2 requires a sufficiently large electric field E^2> M^2+1/4 in order to overcome the confining effect of the AdS geometry -- put in another way, the presence of an electric field E raises the Breitenlohner-Freedman bound to M^2 > -1/4 + E^2. For E greater than this threshold, the vacuum is unstable to production of charged pairs in the bulk. We expect our results to be helpful in constructing supersymmetric AdS_2 X S^2 perturbative string vacua, which enter in the near-horizon limit of extremal charged black holes. Although the generalized Breit...

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Soil fumigation has recently been shown to affect the greenhouse gas balance by increasing emissions of nitrous oxide (N 2 O) following chloropicrin (CP) application. However, the exact mechanisms of this increase were not investigated. The purpose of this study was to elucidate potential mechanisms of CP-induced N 2 O production through laboratory incubations using chemical inhibitors (acetylene, antibacterial, antifungal, and oxygen), isotopically labeled 15 N-CP, and pH modifications of a forest nursery soil. Results showed that N 2 O production increased by 12.6 times following CP fumigation. Microbial activity contributed 82% to the CP-induced N 2 O production, with the remaining 18% from abiotic processes as determined by incubation with sterilized soil. Inhibitor studies suggested that 20% of the N 2 O production was from bacteria and 70% from fungi. There were no significant differences in N 2 O production following CP fumigation under various levels of acetylene (0, 10, and 10 kPa), suggesting that traditional nitrification and denitification reactions did not significantly contribute to N 2 O production following CP fumigation. 15 N labeled studies indicated that 12% of fumigant source N was incorporated into the produced N 2 O. No enrichment in N 2 was observed, indicating that N 2 O was one of the terminal biotic mineralization products of CP. Production of N 2 O is aerobic and production rates increased with increasing oxygen concentrations. Our data strongly suggested that fungal mediated denitrification reactions under aerobic conditions were the primary mechanism for CP-induced N 2 O production.

For the first time it was possible to investigate a still poorly known region of the eastern Mediterranean Sea, the Libyan continental margin. An oceanographic cruise, performed during summer 2006, revealed an important and novel feature: a dense vein flowing along the continental slope. The paper describes the vein evolution with some insights on its dynamic and furnishes an estimate of its transport, which results to be comparable with the Adriatic Deep Water production rate. The cascading into a steep canyon which incises the continental shelf suggests that the vein may play an important role in ventilating the deep layers of the Ionian Sea.

The present study was designed to examine the influence of oocyte quality, culture media and gonadotropins on cleavage rate and development of in vitro fertilized buffalo embryos. Three experiments were conducted. In experiment 1, oocytes were classified by number of cumulus cell layers and morphology of the ooplasm as good, fair or poor. Oocytes were cultured for IVM, IVF and IVC in CR1aa medium. In experiment 2, good quality oocytes were cultured for maturation in: (1) CR1aa; (2) CR2aa; (3) TCM-199; (4) MEM or (5) RPMI-1640, and then fertilized using frozen thawed buffalo spermatozoa in CR1aa. The oocytes were cultured in the same medium used for maturation after fertilization. In experiment 3, oocytes were classified into three groups: group (1) was without gonadotropin and serve as a control; group (2) in which IVM medium was supplemented with 10 g/ml FSH and group (3) in which IVM medium was supplemented with 10 IU ml −1 eCG.

Performing experiments with transactinide elements demands highly sensitive detection methods due to the extremely low production rates (one-atom-at-a-time conditions). Preseparation with a physical recoil separator is a powerful method to significantly reduce the background in experiments with sufficiently long-lived isotopes (t 1/2 Z 0.5 s). In the last years, the new gas-filled TransActinide Separator and Chemistry Apparatus (TASCA) was installed and successfully commissioned at GSI. Here, we report on the design and performance of a Recoil Transfer Chamber (RTC) for TASCA-an interface to connect various chemistry and counting setups with the separator. Nuclear reaction products recoiling out of the target are separated according to their magnetic rigidity within TASCA, and the wanted products are guided to the focal plane of TASCA. In the focal plane, they pass a thin Mylar window that separates the $ 1 mbar atmosphere in TASCA from the RTC kept at $ 1 bar. The ions are stopped in the RTC and transported by a continuous gas flow from the RTC to the ancillary setup. In this paper, we report on measurements of the transportation yields under various conditions and on the first chemistry experiments at TASCA-an electrochemistry experiment with osmium and an ion exchange experiment with the transactinide element rutherfordium.

Purpose -The purpose of this paper is to present a new generic Petri net (PN) model based on assembly plan for assembly sequence optimization. The model aims to allow modeling the flexible assembly system (FAS) configuration, determining the optimal work in process, lead time, throughput, and utilization of each station. Moreover, it aims to show assembly features (AFs) as being useful in assembly sequence planning. Design/methodology/approach -Sophisticated knowledge of AFs is used to get very few feasible assembly sequences (ASs) rather than all possible ASs for a product. A PN model is developed to find out the near optimal assembly sequence out of the sequences obtained from the AF knowledge. It is also used for design and performance evaluation of FAS. Multiple optimization criteria are used for assembly sequence optimization, keeping in view the line balancing. The PN is optimized using weighted-WIP when the throughput is bounded by the utilization of the bottleneck machines. Findings -The results achieved from the example show a considerable reduction in the number of feasible ASs for a product. The PN optimization gives minimum WIP corresponding to the maximum production rate. Moreover, the PN model pushes more inventories to the initial assembly phase.

This paper summarizes our results on the changes in pelagic calci"cation and the standing stock of calcium carbonate associated with the SW Monsoon and NE Monsoon (cruises TN049 and TN053 of the U.S. JGOFS study, respectively) in the northern portion of the Arabian Sea. Mean calci"cation was &3X greater during the SW Monsoon than during the NE Monsoon. Calci"cation per coccolithophore was 7}10X higher, and the ratio of calci"cation to photosynthesis (C/P) was 40}45% higher during the SW Monsoon. The turnover time of PIC was not statistically di!erent between the two cruises (&4.5 d averaged over the euphotic zone). Turnover time of POC increased signi"cantly between TN049 and TN053 (from &3 to 6 d over the euphotic zone). We discuss vertical sections of coccolithophore abundance, carbon standing stocks and carbon "xation. Coccolithophore calci"cation was usually about 1}5% of community photosynthesis. The ratio of calci"cation to photosynthesis spanned almost 2 orders of magnitude, and was not signi"cantly di!erent from the ratio of the PIC and POC standing stocks. We compare surface PIC and POC production rates to sediment trap #uxes from the same region.

Total body turnover of cholesterol was studied in 54 subjects by fitting a three-pool mathematical model to plasma decay curves of 32-49 weeks duration following ['4C]cholesterol injection. Fifteen subjects were normal, 10 hypercholesterolemic, 2 1 hypertriglyceridemic, and 8 had both hypercholesterolemia and hypertriglyceridemia; 2 1 had a familial form of hyperlipidemia. In every subject in this heterogeneous population, the three-pool model gave the best fit for the data.

All, but no tendency to precocious atherosclerosis is present. To elucidate this paradox, the structure of HDL, the potential of serum to promote cholesterol effiux from cultured cells, and the in vivo metabolism of HDL were examined in a 53-year-old Woman with a FED syndrome in association with a markedly decreased lecithin:cholesterol acyltransferase (LCAT) activity in HDL due to a mutation of the LCAT gene (Arglse -~ Cys). HDLs isolated by uitracentrifugation were small and enriched in unesterified cholesterol and phospholipids at the expense of cholesteryl esters and proteins, The apolipoprotein content showed an enrichment in apo E and apo AIV, whereas apo AI and apo All were dramatically reduced. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE} and immunoblotting using specific antibodies showed that the apo E was free or covalently bound to apo All. These particles analyzed by electron microscopy were small and round lipoproteins with a size similar to the smallest fraction of normal HDL3. The potential capacity of the serum to promote efflux from the cells was approximately 40% of control serum levels, but FED HDLs were as efficient as control HDLs in promoting cholesterol efflux from cells. To assess the metabolism of HDL apolipoproteins, in vivo apolipoprotein kinetic studies were performed using endogenous labeling techniques in the patient with FED and three control subjects. All subjects were administered D3-1abeled leucine by primed constant infusion for up to 10 hours. The fractional synthetic rates (FSRs) of apo AI and apo All in the patient were 0.674 and 0,594 per day, clearly higher than in controls, 0.210 +-0.053 and 0.148 +-0.014 per day for apo AI and apo All, respectively. Apo AI and apo All production rates in the patient with FED were normal, 11.32 and 2.62 mgJkg • d, respectively, as compared with those in normal subjects, 11.45 + 1.23 and 2.68 -+ 0.17 mg/kg • d. These data established that hypoalphalipoproteinemia in FED was caused by marked hypercatabolism of apo AI and apo All. This hypercatabolism could be the consequence of structural abnormalities due to the selective LCAT deficiency, in conclusion, two steps of reverse cholesterol transport, cholesterol efflux and apo-HDL metabolism, appeared particularly efficient. This efficiency could participate in the absence of premature atherosclerosis in FED patients as regards the low HDL level.

Large projectiles impacting the Earth will cause severe shock heating and chemical reprocessing of the Earth's atmosphere. This occurs during atmospheric entry and, more importantly, as a result of the supersonic plume ejected on impact. In particular, very large amounts of nitric oxide would result from the impact of the putative Cretaceous-Tertiary bolide(s). We present models of the shock chemistry, the conversion of NO to NO 2 and thence to nitrous and nitric acids, and the global dispersion of the NO 2 and acids. Two plausible projectiles are considered: an ice-rich long-period comet and a much smaller rock-metal asteroid. The comet produces semi-global atmospheric NO 2 mixing ratios of 0.1% while the asteroid produces these high mixing ratios only in the immediate region of the impact. The comet produces concentrated nitrous and nitric acid rain with a pH ~ 0-1.5 globally. The asteroid produces rain with a pH ~ 0-1 near the impact and-4-5 globally. Immediate environmental effects of these nitrogen species include inhibition of photosynthesis due to extinction of solar radiation by NO 2, foliage damage due to exposure to NO 2 and HNO 3, toxicosis resulting from massive mobilization of soil trace metals, and respiratory damage due to exposure to NO 2. The acid rain decreases the pH of the oceanic mixed layer affecting the stability of calcite with important implications for the survival of calcareous-shelled organisms and for exhalation of CO, from the mixed layer to the atmosphere. Longer-term environmental effects perhaps-1000 years in duration include a global warming due to the sudden CO 2 injection and the simultaneous extinction of the ocean microorganisms which normally help remove CO 2 from the atmosphere-mixed layer system. Havens for survival include carbonate-buffered lakes and burrows. This acid rain theory therefore serves to explain the peculiar selectivity of the extinctions seen at the Cretaceous-Tertiary boundary. The first few years of acid rain will lead to massive weathering rates of continental soils characterized by large ratios of the relatively insoluble metals (e.g. Be 2+, AI ~, Hg 2., Cu*, Fe 2+, Fe 3+, T13+, Pb 2+, Cd 2~, Mn 2., Sr 2.) to the more soluble metals (Ca 2 +, Mg 2 +) which should have left a clear signal in the fossils of neritic organisms and in unperturbed neritic sediments near river deltas if such sediments still exist for the Cretaceous-Tertiary time frame.

This paper describes the linkage of a three-dimensional hydrodynamic circulation model with descriptive and experimental biological data concerning oyster (Crassostrea virginica) population dynamics in the Apalachicola Estuary (Florida, U.S.A.). Our intent was to determine the direct and indirect role of Apalachicola River flow in the maintenance of oyster production. Results of a monthly field sampling programme conducted on the oyster reefs in the Apalachicola system during 1985-1986 were used to develop statistical models relating several life-history characteristics of oysters to physical-chemical aspects of water quality. The same life-history characteristics were related statistically to output from a circulation model of Apalachicola Bay. Highest oyster densities and overall bar growth were found in the vicinity of the confluence of high salinity water moving westwards from St George Sound and river-dominated (low salinity) water moving south and eastwards from East Bay. With the exception of models for oyster mortality, the predictive capability of results from the parallel modelling efforts was low. A time-averaged model was developed for oyster mortality during the summer of 1985 by running a regression analysis with averaged predictors derived from the hydrodynamic model and observed (experimental) mortality rates throughout the estuary. A geographic information system was then used to depict the results spatially and to compare the extent of expected mortality in 1985 and 1986. High salinity, relatively low-velocity current patterns, and the proximity of a given oyster bar to entry points of saline Gulf water into the bay were important factors that contribute to increased oyster mortality. Mortality was a major determinant of oyster production in the Apalachicola Estuary with predation as a significant aspect of such mortality. By influencing salinity levels and current patterns throughout the bay, the Apalachicola River was important in controlling such mortality. Oyster production rates in the Apalachicola system depend on a combination of variables that are directly and indirectly associated with freshwater input as modified by wind, tidal factors, and the physiography of the bay. River flow reduction, whether through naturally occurring droughts, through increased upstream anthropogenous (consumptive) water use, or a combination of the two, could have serious adverse consequences for oyster populations. By coupling hydrodynamic modelling with descriptive and experimental biological data, we were able to determine the effects of potential freshwater diversions on oyster production in Apalachicola Bay.

Biomethanation Cookstove Appropriate technology Renewable energy a b s t r a c t Low-cost tubular digesters originally developed in tropical regions have been adapted to the extreme weather conditions of the Andean Plateau (3000e4000 m.a.s.l.). The aim of this study was to characterise biogas production in household digesters located at high altitude, operating under psychrophilic conditions. To this end, two pilot digesters were monitored and field campaigns were carried out in two representative digesters of rural communities.

Marine aerosols produced by bursting bubbles at the ocean surface are highly enriched in organic matter (OM) relative to seawater. The importance of this OM in the photochemical evolution of marine aerosols and particularly as a source of reactive oxidants are unknown but likely significant. To investigate oxidant production, nascent aerosols were generated by bubbling zero air through flowing Sargasso seawater and photochemical production of OH radical and hydroperoxide were quantified in aqueous extracts exposed to solar radiation. Extrapolation to ambient conditions indicates that OM photolysis was the primary in situ source for OH (1.1 x10 -8 M s -1 ) and hydroperoxides (1.7 x 10 -8 M s -1 ) in nascent aerosols; NO 3 photolysis was the primary source in aged, acidified aerosols (1.4×10 -7 and 4.1×10 -8 M s -1 , respectively). In situ OH photoproduction was comparable to gas-phase uptake whereas H 2 O 2 photoproduction was slower.

Anaerobic digestion is an appropriate technique for the treatment of sludge before final disposal and it is employed worldwide as the oldest and most important process for sludge stabilization. In general, mesophilic anaerobic digestion of sewage sludge is more widely used compared to thermophilic digestion. Furthermore, thermal pre-treatment is suitable for the improvement of stabilization, enhancement of dewatering of the

Maximum ethanol productions of two enological yeast strains (Sacc.haromyces cerevisiae K1 and 738-2) were compared during alcoholic fermentation under conditions where substrate was not a limiting factor. Although strain 738-2 seemed to exhibit the lowest sensitivity to ethanol, the strain Ki showed a higher production of ethanol, and a higher CO 2 production rate in presence of ethanol than the strain 738-2.

Twenty pH-controlled batch cultures with Lactobacillus helveticus were carried out in whey permeate-yeast extract medium according to a composite design with three factors: pH setpoint, and yeast extract and initial whey permeate concentrations. Growth and production parameters were estimated from experimental data with the Richards and Luedeking and Piret models, respectively, and analyzed statistically with response surfaces. The maximum specific growth rate, max , depended primarily on pH, with an optimum of 0.7 h Ϫ1 near pH 5.5. Whey permeate concentration had no direct effect on maximum specific growth rate, but showed a strong interaction with pH. Yeast extract addition had a strong positive effect on maximum specific growth rate. During nitrogen-limited batch cultures X max depended on yeast extract concentration and pH, as well as on interactions of these variables with whey permeate concentration. The growth-associated lactic acid production parameter a was constant at 4.5 g lactic acid (g biomass) Ϫ1 , while the nongrowth-associated production parameter b, estimated during growth and early stationary phase, was a linear function of pH. This study allowed for the first detailed multifactor kinetic analysis of Lb. helveticus growth and lactic acid production, with a limited number of experiments, and demonstrated the importance of interactions among tested culture conditions.

This paper focuses on the perception and production of the English alveolar stops (/t / and /d/) in syllable coda by Brazilian learners of English. In the production test, the participants read a list of English sentences containing alveolar stops in word-final position. The preceding and following phonological contexts were controlled, so that the effect of context on the production of the alveolar stops could be analyzed. The perception test consisted of an oddity discrimination task where the target obstruents were either unreleased, aspirated, palatalized or produced with a paragogic vowel. The results of the production investigation show that the learners tended to unrelease the obstruents, but several tokens were aspirated, palatalized or produced with a paragogic vowel. As regards the relationship between perception and production of word-final /t / and /d/, a positive correlation was found between the discrimination and production rates. Index Terms: L2 perception/production...

Beginning in 1992, the Slow The Spread (STS) pilot project was initiated to target gypsy moth (Lymantria dispar L.) spread rate reduction by controlling populations in the transition zone. The project uses intensive monitoring techniques, with pheromone-baited sticky moth traps, to detect low-level populations and target them for eradication. The primary objective of the pilot project was to evaluate the feasibility of using integrated pest management techniques to slow the spread of gypsy moths over a large geographical area. In this study, the cost of STS pilot project activities in 1993Ð1995 was investigated. A cost accounting system was developed and used as a framework to collect the cost data and to investigate cost patterns and characteristics. Total expenditures of STS activities for 1993Ð1995 were $7,685.2 million. Per unit cost was $49.67 per trap with the direct cost component being $35.03 per trap. Trapper labor and vehicle expense accounted for Ϸ90% of this direct cost. Per unit cost for treatment activities was found to average $27.86 per treated acre. In general, the STS pilot project is labor intensive, speciÞcally the trapping component. From 1993Ð1995, 59% of total project expenditures were spent on trapping activities, 28% on pesticide treatments, and 13% on data management. A trapper productivity rate regression model is described.

Earthworm casts, formed when organic substrates and soil minerals pass through the digestive tract, may protect soil organic matter from biological degradation if they persist in the soil. Yet, the stability of casts is affected by their location in the soil profile because surface casts are exposed to more disruptive forces (wetting-drying, freezing-thawing) than subsurface casts. It is not known

Thermophilic anaerobic digestion offers an attractive alternative for the treatment of medium-and high-strength wastewaters. However, literature reports reveal that thermophilic wastewater treatment systems are often more sensitive to environmental changes than the well-defined high-rate reactors at the mesophilic temperature range. Also, in many cases a poorer effluent quality is experienced while the carry over of suspended solids in the effluent is relatively high. In this paper recent achievements are discussed regarding the process stability of thermophilic anaerobic wastewater treatment systems. Laboratory experiments reveal a relatively low sensitivity to temperature changes if high-rate reactors with immobilized biomass are used. Other results show that if a staged process is applied, thermophilic reactors can be operated for prolonged periods of time under extreme loading conditions (80-100 kg chemical oxygen demand.m-3.day-1),,while the concentrations of volatile fatty acids in the effluent remain at a low level.

Palaeoceanographic conditions in the eastern Indian Ocean for the last ¾30 kyr are documented by means of planktonic foraminiferal analyses of 10 gravity cores. Quantitative foraminiferal analysis (%), Q-mode factor analysis, the modern analog technique (MAT) and oxygen-isotope analyses are used. A conspicuous increase during the last glacial maximum (LGM) of foraminiferal fragmentation resulting from a more productive Java upwelling system and=or a more corrosive Antarctic Intermediate Water (AAIW) was found at intermediate water depths (¾1000 m). Contrasting Q-mode factors based on foraminifera between today and the LGM suggest changes in the thermocline depth, sea-surface temperature (SST), upwelling, and the strength of both the Australasian Mediterranean Water (AAMW) and the Indian Central Water (ICW). The decrease in the percentage abundance of shallow-dwelling and symbiont-bearing planktonic foraminifera, the increase in percentage of the upwelling-related species Globorotalia cultrata and Neogloboquadrina dutertrei, and factor 3 (dominated by Globorotalia tumida and Globigerinella siphonifera) suggest a stronger Java upwelling system during the LGM. A steeper, steric latitudinal gradient (in the presence of a weak Leeuwin Current), and a geostrophic flow similar to today's is postulated for the LGM, and this must have prevented upwelling offshore Western Australia. Today's AAMW-ICW sharp front was weaker during the LGM when the AAMW was saltier, cooler, and nutrient richer and more similar to the ICW. During the LGM, a more gentle SST latitudinal gradient over the ¾16 to ¾23ºS region contrasts with today's steeper conditions at the AAMW-ICW Front. Also, for the LGM, a nutrient-rich ICW may explain previously documented increases in mass accumulation rates of CaCO 3 , organic carbon and benthonic foraminifera in a region where the nutricline was deep and within the lower euphotic zone.

Planet formation models suggest the primordial main belt experienced a short but intense period of collisional evolution shortly after the formation of planetary embryos. This period is believed to have lasted until Jupiter reached its full size, when dynamical processes (e.g., sweeping resonances, excitation via planetary embryos) ejected most planetesimals from the main belt zone. The few planetesimals left behind continued to undergo comminution at a reduced rate until the present day. We investigated how this scenario affects the main belt size distribution over Solar System history using a collisional evolution model (CoEM) that accounts for these events. CoEM does not explicitly include results from dynamical models, but instead treats the unknown size of the primordial main belt and the nature/timing of its dynamical depletion using innovative but approximate methods. Model constraints were provided by the observed size frequency distribution of the asteroid belt, the observed population of asteroid families, the cratered surface of differentiated Asteroid (4) Vesta, and the relatively constant crater production rate of the Earth and Moon over the last 3 Gyr. Using CoEM, we solved for both the shape of the initial main belt size distribution after accretion and the asteroid disruption scaling law Q * D . In contrast to previous efforts, we find our derived Q * D function is very similar to results produced by numerical hydrocode simulations of asteroid impacts. Our best fit results suggest the asteroid belt experienced as much comminution over its early history as it has since it reached its low-mass state approximately 3.9-4.5 Ga. These results suggest the main belt's wavy-shaped size-frequency distribution is a "fossil" from this violent early epoch. We find that most diameter D 120 km asteroids are primordial, with their physical properties likely determined during the accretion epoch. Conversely, most smaller asteroids are byproducts of fragmentation events. The observed changes in the asteroid spin rate and lightcurve distributions near D ∼ 100-120 km are likely to be a byproduct of this difference. Estimates based on our results imply the primordial main belt population (in the form of D < 1000 km bodies) was 150-250 times larger than it is today, in agreement with recent dynamical simulations.

In the current environment of rapid technological change, the printed circuit card assembly manufacturer is often required to produce a wide variety of circuit card assemblies while maintaining a high level of quality and minimizing both production time and cost. Assembly automation has also become very expensive, in terms of both initial investment cost and operating costs. Thus optimizing assembly processes to achieve high levels of utilization and production, with minimal work-inprocess inventory, is increasingly important. Process planning can represent a significant factor in achieving both of these objectives. This paper presents the decision problems in process planning, our solution approaches for these problems, and the implementation results from our experiences to date with industrial partners.

In the current environment of rapid technological change, the printed circuit card assembly manufacturer is often required to produce a wide variety of circuit card assemblies while maintaining a high level of quality and minimizing both production time and cost. Assembly automation has also become very expensive, in terms of both initial investment cost and operating costs. Thus optimizing assembly processes to achieve high levels of utilization and production, with minimal work-inprocess inventory, is increasingly important. Process planning can represent a significant factor in achieving both of these objectives. This paper presents the decision problems in process planning, our solution approaches for these problems, and the implementation results from our experiences to date with industrial partners.

Two starchy substrates like pumpkin and cane molasses were selected for citric acid fermentation by using gamma ray induced mutant strains of 14/20 and 79/20 of A. niger under surface culture condition. Citric acid production was also different with various fermentation media by A. niger 14/20 and 79/20 strains. It was found to increase with the increase of fermentation period and maximum citric acid was found on day 13. In the presence of Prescott salt citric acid production was found lower than the absence of Prescott salt. Without Prescott salt highest values of citric acid production was found in mixed fermentation medium which were about 14.86 mg/ml and 14.44 mg/ml for A. niger 14/20 and 79/20 strains respectively, lowest production of citric acid was found in molasses medium for A. niger 14/20 and 79/20 strains were 7.72 and 7.57 mg/ml respectively. Whereas in the presence of Prescott salt, lowest production of citric acid in Pumpkin medium was found 2.86 mg/ml for A. niger 14/20 and 2.7 mg/ml for A. niger 79/20. Highest amount of citric acid was produced in molasses medium 4.88 mg/ml for A. niger 14/20 on day 13 with the presence of Prescott salt whereas 4.75 mg/ml for A. niger 79/20 strains respectively. Mixed substrate prepared with molasses and pumpkin media was proved to be the best and potential for citric acid production.

The concept of glycolysis optimization, first presented in Waddell (Biochemical Education 25 (1997) 204-205) and Heinrich et al. (Eur. J. Biochem. 243 (1997) 191-201), is reiterated and clarified in response to questions by Christoffersen et al. (Biochemical Education 26 (1998) 290-291). Indeed, increasing the ATP yield above 2ATP/glucose would lcad to a decrease in the ATP production rate and a lower flux of material toward lactate. O 1999 IUBMB. Published by Elsevier Science IJd. All rights reserved.

In view of the current increase in atmospheric pCO2 and concomitant changes in the marine environment, it is crucial to assess, understand, and predict future responses of ecologically relevant phytoplankton species. The diazotrophic cyanobacterium Trichodesmium erythraeum was found to respond strongly to elevated pCO2 by increasing growth, production rates, and N2 fixation. The magnitude of these CO2 effects exceeds those previously seen in other phytoplankton, raising the question about the underlying mechanisms. Here, we review recent publications on metabolic pathways of Trichodesmium from a gene transcription level to the protein activities and energy fluxes. Diurnal patterns of nitrogenase activity change markedly with CO2 availability, causing higher diel N2 fixation rates under elevated pCO2. The observed responses to elevated pCO2 could not be attributed to enhanced energy generation via gross photosynthesis, although there are indications for CO2-dependent changes in ATP/NADPH + H+ production. The CO2 concentrating mechanism (CCM) in Trichodesmium is primarily based on HCO3− uptake. Although only little CO2 uptake was detected, the NDH complex seems to play a crucial role in internal cycling of inorganic carbon, especially under elevated pCO2. Affinities for inorganic carbon change over the day, closely following the pattern in N2 fixation, and generally decrease with increasing pCO2. This down-regulation of CCM activity and the simultaneously enhanced N2 fixation point to a shift in energy allocation from carbon acquisition to N2 fixation under elevated pCO2 levels. A strong light modulation of CO2 effects further corroborates the role of energy fluxes as a key to understand the responses of Trichodesmium.

Models are needed for forecasting the effects of eutrophication on stream and river ecosystems. Most of the current models do not include differences in local stream characteristics and effects on the biota. To define the most important variables that should be used in a stream eutrophication model, the literature was reviewed.

The effect of inoculum level of Lactobacillus curvatus on Nham fermentation was studied. Nham inoculated with L. curvatus at 10 4 (LC104) and 10 6 cfu/g (LC106) exhibited a higher rate of fermentation than naturally fermented Nham (control) as indicated by greater rate of pH drop, lactic acid production, and changes in protein compositions. Based on the pH, the fermentation was completed within 72, 48 and 36 h for control, LC104, and LC106, respectively. Higher extent of proteolysis and lipolysis were observed during fermentation of Nham inoculated with starter bacteria (Po0:05). Due to higher acid production rate and extent, texture development of inoculated Nham was more rapid. Inoculated Nham exhibited higher TPA hardness and adhesiveness but lower fracturability than naturally fermented Nham (Po0:05). In terms of acceptability, control and LC104 had higher ratings on the overall liking than LC106 (Po0:05). However, LC104 was better accepted than control in terms of flavour, sourness, saltiness, and texture. Unusual smell was detected only in Nham inoculated at 10 6 cfu/g. Based on physico-chemical properties and consumer acceptability, L. curvatus is a potential starter for Nham fermentation. However, inoculation of L. curvatus at high level may cause off-flavour in the product.

We report observational evidence for water ice in comet C/1995 O1 (Hale-Bopp) when it was at 2.9 AU from the Sun, from emission features at 44 and 65 mu m, and possibly an absorption feature at 3.1 mu m, observed with ISO/LWS and PHT. We find that icy grains have mean radii of 15 mu m within a factor of

The aim of the current study was to examine effects of daily temperature variations on the performance of anaerobic digestion. Forced square-wave temperature variations (between 11 and 25, 15 and 28, and 19 and 32°C) were imposed on a bench-scale digester using a mixture of llama-cow-sheep manure in a semi-continuous process. The volumetric biogas production rate, methane yield, and the volatile solid reductions were compared with the results obtained from anaerobic digestion (AD) at constant temperatures.

This paper deals with the development of a System Dynamics Model to study the influence of Production cycle time on: Production start rate, Work in progress, Production rate, Distribution inventory, Distribution rate, and Waste rate. The simulation results indicate that Production cycle time has a significant influence on 'Bullwhip Effect' and there may be a need to stretch the Production cycle time and reduce the delays to minimize this effect. Reduction of Bullwhip effect is a constant endeavour in Supply Chain Management (SCM) and this paper is also an attempt in this direction with specific reference to the influence of Production cycle time.

Paper and cardboard stand for the major biodegradable organic fraction of most of municipal solid waste (MSW). This article aims at discussing the possible positive impact of a thin shredding of this fraction on its biodegradability under mesophilic anaerobic conditions, either for landfilling or for digestion in industrial reactors. For that purpose, BMP tests were performed on two types of paper and cardboard mixtures: one sorted from a complex landfill French MSW income, one built from source separated papers and cardboards. For both of these substrates, comparison was made between assays on large pieces of waste and assays on tiny shredded waste (powder particles of less than 1 mm diameter). For the second substrate, assays at two different inoculation levels were performed. All results are discussed both in terms of maximal methane conversion yields and in terms of kinetic rates. The main conclusion is that shredding does not improve methane potential of paper and cardboard, neither the biogas production rates. This leads the authors to put forward the hypothesis that shredding does not significantly either increase enzyme accessibility to cellulose nor favor the surface bacterial colonization, although it strongly affects the macrostructure of the waste.

The determination of dissolved CO 2 and HCO/ ( 3 concentrations as well as the carbon dioxide production rate in mammalian cell suspension culture is attracting more and more attention since the effects on major cell properties, such as cell growth rate, product quality/production rate, intracellular pH and apoptosis, have been revealed. But the determination of these parameters by gas analysis is complicated by the solution/dissolution of carbon dioxide in the culture medium. This means that the carbon dioxide transfer rate (CTR; which can easily be calculated from off-gas measurement) is not necessarily equal to carbon dioxide production rate (CPR). In this paper, a mathematical method to utilize off-gas measurement and culture pH for cell suspension culture is presented. The method takes pH changes, buffer and medium characteristics that effect CO 2 mass transfer into account. These calculations, based on a profound set of equations, allow the determination of the respiratory activity of the cells, as well as the determination of dissolved CO 2 , HCO/ ( 3 and total dissolved carbonate. The method is illustrated by application to experimental data. The calculated dissolved CO 2 concentrations are compared with measurements from an electrochemical CO 2 probe. #