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Conservative Estimate (conservative + estimate)
Selected AbstractsThe unseen majority: soil microbes as drivers of plant diversity and productivity in terrestrial ecosystemsECOLOGY LETTERS, Issue 3 2008Marcel G. A. Van Der Heijden Abstract Microbes are the unseen majority in soil and comprise a large portion of life's genetic diversity. Despite their abundance, the impact of soil microbes on ecosystem processes is still poorly understood. Here we explore the various roles that soil microbes play in terrestrial ecosystems with special emphasis on their contribution to plant productivity and diversity. Soil microbes are important regulators of plant productivity, especially in nutrient poor ecosystems where plant symbionts are responsible for the acquisition of limiting nutrients. Mycorrhizal fungi and nitrogen-fixing bacteria are responsible for c. 5,20% (grassland and savannah) to 80% (temperate and boreal forests) of all nitrogen, and up to 75% of phosphorus, that is acquired by plants annually. Free-living microbes also strongly regulate plant productivity, through the mineralization of, and competition for, nutrients that sustain plant productivity. Soil microbes, including microbial pathogens, are also important regulators of plant community dynamics and plant diversity, determining plant abundance and, in some cases, facilitating invasion by exotic plants. Conservative estimates suggest that c. 20 000 plant species are completely dependent on microbial symbionts for growth and survival pointing to the importance of soil microbes as regulators of plant species richness on Earth. Overall, this review shows that soil microbes must be considered as important drivers of plant diversity and productivity in terrestrial ecosystems. [source] Alcohol and Russian mortality: a continuing crisisADDICTION, Issue 10 2009David A. Leon ABSTRACT Background Russia remains in the grip of a mortality crisis in which alcohol plays a central role. In 2007, male life expectancy at birth was 61 years, while for females it was 74 years. Alcohol is implicated particularly in deaths among working-age men. Aims To review the current state of knowledge about the contribution of alcohol to the continuing very high mortality seen among Russian adults Results Conservative estimates attribute 31,43% of deaths among working-age men to alcohol. This latter estimate would imply a minimum of 170 000 excess deaths due to hazardous alcohol consumption in Russia per year. Men drink appreciably more than women in Russia. Hazardous drinking is most prevalent among people with low levels of education and those who are economically disadvantaged, partly because some of the available sources of ethanol are very cheap and easy to obtain. The best estimates available suggest that per capita consumption among adults is 15,18 litres of pure ethanol per year. However, reliable estimation of the total volume of alcohol consumed per capita in Russia is very difficult because of the diversity of sources of ethanol that are available, for many of which data do not exist. These include both illegal spirits, as well as legal non-beverage alcohols (such as medicinal tinctures). In 2006 regulations were introduced aimed at reducing the production and sale of non-beverage alcohols that are commonly drunk. These appear to have been only partially successful. Conclusion There is convincing evidence that alcohol plays an important role in explaining high mortality in Russia, in particular among working age men. However, there remain important uncertainties about the precise scale of the problem and about the health effects of the distinctive pattern of alcohol consumption that is prevalent in Russia today. While there is a need for further research, enough is known to justify the development of a comprehensive inter-sectoral alcohol control strategy. The recent fall in life expectancy in Russia should give a renewed urgency to attempts to move the policy agenda forward. [source] Levels of literacy among juvenile offenders: the incidence of specific reading difficultiesCRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 4 2000Margaret J. Snowling Introduction Academic achievement is low among offenders. Yet there is little evidence that prisoners are less literate than the general population. Do they have more dyslexia? This paper considers three definitions of dyslexia to see whether they relate to young offenders' literacy difficulties. Method The reading and spelling skills of 91 15- to 17-year-old male juvenile offenders who were incarcerated are reported, together with assessments of their vocabulary and non-verbal (spatial) skills. Estimates of the prevalence of reading disability are considered in relation to different definitions of dyslexia. Results The regression of literacy skills on non-verbal ability yielded an estimated prevalence of 57% while a more conservative estimate of 43% followed from the regression of literacy skill on verbal ability, and 38% of the sample had specific phonological deficits. Many of the offenders had experienced social and family adversity and reported poor school attendance. Discussion It is proposed that as a group, juvenile offenders are best described as having general verbal deficits encompassing problems of language and literacy. Copyright © 2000 Whurr Publishers Ltd. [source] Micromorphological evidence of black carbon in colluvial soils from NW SpainEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2008J. Kaal Summary Biomass burning produces a residue called black carbon (BC). Black C is generally considered to be highly resistant against biodegradation and has a potential role in the global C cycle, but is difficult to identify and quantify when subjected to prolonged degradation in terrestrial sediments. The colluvial soils from Campo Lameiro (NW Spain), also known as ,Atlantic rankers', are rich in organic matter (up to 140 g C kg,1 soil). A micromorphological study was undertaken to test the hypothesis that a large proportion of the organic matter was derived from BC formed during Holocene wildfires (up to > 6000 years ago). As roughly estimated from image analysis of 12 thin sections, the volumetric BC contribution ranged between 10 and 60% (26% on average) of the organic matter. This is a conservative estimate as additional morphologically unrecognizable BC was present in the microgranular matrix of coalesced excrement. We conclude that (i) currently unknown quantities of BC are stored in Atlantic rankers and (ii) analysis of thin sections is an effective tool to identify BC. [source] Reliability analysis of universal joint of a compliant platformFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 7 2010M. M. ZAHEER ABSTRACT The paper describes a methodology for computation of fatigue reliability of universal joint in an articulated offshore tower. Failure criteria were formulated using the conventional Palmgren-Miner rule (S-N curve approach) and the fracture mechanics (F-M) principle. The dynamic analysis of double hinged articulated tower under wind and waves is carried out in time domain. The response histories of hinge shear stresses are employed for the reliability analysis. Advanced first-order reliability method and Monte Carlo simulation method were used to estimate the reliability. Various parametric studies were carried out, which yield important information for the reliability based design. The S-N curve approach yields a significantly conservative estimate of probability of failure when compared to the F-M approach. [source] Prediction of crack opening stress levels for 1045 quenched and tempered steel under service loading spectraFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 1 2006M. KHALIL ABSTRACT The opening stresses of a crack emanating from an edge notch in a 1045 quenched and tempered steel specimen were measured under two different Society of Automotive Engineers (SAE) standard service load histories having different average mean stress levels. The two spectra are the Grapple Skidder history (GSH), which has a positive average mean stress, and the Log Skidder history (LSH), which has a zero average mean stress. To capture the behaviour of the crack opening stress in the material, the crack opening stress levels were measured at 900X using an optical video microscope, at frequent intervals for each set of histories scaled to two different maximum stress ranges. A crack growth analysis based on a fracture mechanics approach was used to model the fatigue behaviour of the steel specimens for the given load spectra and stress ranges. Crack growth analysis was based on an effective strain-based intensity factor, a crack growth rate curve obtained during closure-free loading cycles and a local notch strain calculation based on Neuber's rule. The crack opening stress (Sop) was modelled and the model was implemented in a fatigue notch model, and the fatigue lives of the specimens under the two different spectra scaled to several maximum stress levels were estimated. The average measured crack opening stresses were between 6 and 12% of the average calculated crack opening stresses. In the interest of simplifying the use of Sop in design, the average Sop was correlated with the frequency of occurrence of the cycle reducing the Sop to the average crack opening stress level. The use of an Sop level corresponding to the cycle causing a reduction in Sop to a level reached once per 10 cycles gave a conservative estimate of average crack opening stress for all the histories. [source] Optimization study of large-scale low-grade energy recovery from conventional Rankine cycle power plantsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 12 2010K. M. Mohamed Abstract This study evaluates large-scale low-grade energy recovery (LS-LGER) from a conventional coal-fired Rankine cycle (RC) as a ,green' option to offsetting the cost of treating pollution. An energy and exergy analysis of a reference generating station isolates the key areas for investigation into LS-LGER. This is followed by a second law analysis and a detailed optimization study for a revised RC configuration, which provides a conservative estimate of the possible energy recovery. Cycle optimization based on specific power output, and including compact heat exchanger designs, indicates plant efficiency improvements (with high-capacity equipment) of approximately 2 percentage points with reduced environmental impact. Copyright © 2009 John Wiley & Sons, Ltd. [source] FREE CASH FLOW AND PUBLIC GOVERNANCE: THE CASE OF ALASKAJOURNAL OF APPLIED CORPORATE FINANCE, Issue 3 2000Dwight R. Lee In a widely cited 1986 article in the American Economic Review, Michael Jensen gave the concept of free cash flow (FCF) a new twist by redefining it as cash flow in excess of that required to fund all projects with positive net present values. Put another way, FCF represents funds available in the firm that managers may choose to hold as idle cash, return to shareholders, or invest in projects with returns below the firm's cost of capital. In redefining FCF in this way, Jensen converted FCF from a measure of economic income and value into a measure of corporate assets available for discretionary, and potentially value-destroying, use by firm managers. And, as he argued in his important article, managers in mature businesses with substantial free cash flow have a tendency to destroy value by plowing too much capital back into those businesses or, often worse, making ill-advised acquisitions in unrelated businesses. Several methods have been developed in financial markets and internal corporate governance systems to discourage managers from wasting FCF. Better monitoring by boards of directors, large ownership blocks, and properly aligned management compensation contracts are all parts of the solution. And the extraordinary increase in stock repurchases in recent years, invariably applauded by investors, is another illustration of the market's success in encouraging companies to address their free cash flow problems. But if the "FCF problem" of the private sector has attracted considerable attention from finance scholars, the problem is even more acute in the public sector, where FCF can be thought of as tax revenue in excess of what is required to finance well-defined and generally accepted levels of public services. Unlike the private sector, in the public sector there are neither measures nor mechanisms by which to monitor and constrain wasteful spending by elected officials. In this article, the authors attempt to measure the costs to taxpayers of government FCF using the case of Alaska, which since 1969 has received a huge windfall of tax revenue from North Slope oil leases. After examining the state's public finances from 1968 through 1993, the authors offer $25 billion as a conservative estimate of the social losses from Alaska's waste of free cash flow during that 25-year period. [source] Genome size and recombination in angiosperms: a second lookJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2007J. ROSS-IBARRA Abstract Despite dramatic differences in genome size , and thus space for recombination to occur , previous workers found no correlation between recombination rate and genome size in flowering plants. Here I re-investigate these claims using phylogenetic comparative methods to test a large data set of recombination data in angiosperms. I show that genome size is significantly correlated with recombination rate across a wide sampling of species and that change in genome size explains a meaningful proportion (,20%) of variation in recombination rate. I show that the strength of this correlation is comparable with that of several characters previously linked to evolutionary change in recombination rate, but argue that consideration of processes of genome size change likely make the observed correlation a conservative estimate. And finally, although I find that recombination rate increases less than proportionally to change in genome size, several mechanistic and theoretical arguments suggest that this result is not unexpected. [source] A molecular analysis of hybridization between native westslope cutthroat trout and introduced rainbow trout in southeastern British Columbia, CanadaJOURNAL OF FISH BIOLOGY, Issue 2001E. Rubidge Restriction site variation in the Ikaros gene intron was used to assess the incidence of westslope cutthroat trout (Oncorhynchus clarki lewisi), rainbow trout (O. mykiss) and interspecific hybrids at 11 localities among eight streams tributary to the upper Kootenay River system in south-eastern British Columbia, Canada. Out of 356 fish assayed by this technique, hybrids (n=16) were found at seven of the 11 sites across five different streams. Rainbow trout (n=6) were found at two of the 11 sites. Analysis of hybrids with a second genetic marker (heat shock 71 intron) indicated that most represented either backcrosses to both westslope cutthroat and rainbow trout, or post F1 hybrids. Mitochondrial DNA analysis indicated that hybrid matings occur between male rainbow trout and female westslope cutthroat trout and vice versa. Comparison of present hybridization in five tributaries relative to an allozyme-based analysis in the mid-1980s, that documented hybrids in only a single tributary of seven that were common to the two studies, suggests that hybridization and introgression has increased in upper Kootenay River tributaries. The present analysis is a conservative estimate of genetic interaction between the species because introgression was not tested in the majority of samples. Identification of genetically pure westslope cutthroat trout populations, and why they might be resistant to introgression from rainbow trout, are crucial conservation priorities for this unique subspecies of cutthroat trout. [source] Estimating the variance of estimated trends in proportions when there is no unique subject identifierJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES A (STATISTICS IN SOCIETY), Issue 1 2007William K. Mountford Summary., Longitudinal population-based surveys are widely used in the health sciences to study patterns of change over time. In many of these data sets unique patient identifiers are not publicly available, making it impossible to link the repeated measures from the same individual directly. This poses a statistical challenge for making inferences about time trends because repeated measures from the same individual are likely to be positively correlated, i.e., although the time trend that is estimated under the naïve assumption of independence is unbiased, an unbiased estimate of the variance cannot be obtained without knowledge of the subject identifiers linking repeated measures over time. We propose a simple method for obtaining a conservative estimate of variability for making inferences about trends in proportions over time, ensuring that the type I error is no greater than the specified level. The method proposed is illustrated by using longitudinal data on diabetes hospitalization proportions in South Carolina. [source] Human metapneumovirus and respiratory syncytial virus infections in older children with cystic fibrosisPEDIATRIC PULMONOLOGY, Issue 1 2007Daniel F. Garcia MD Abstract Background: Human metapneumovirus (hMPV) has been isolated from children with acute respiratory infection worldwide. Its epidemiology remains to be defined in children with cystic fibrosis (CF). We describe the epidemiology and clinical impact of hMPV in CF children and compared it to respiratory syncytial virus (RSV). Methods: CF children ages 7,18 years were studied prospectively during the 1998,1999 RSV season. Nasopharyngeal specimens were collected during acute respiratory illnesses and tested for respiratory viruses. Blood specimens were drawn early, mid, and end of the RSV season, and tested for serological evidence of hMPV and RSV infections. Rates of lower respiratory tract illnesses (LRTI) and hospitalizations for pulmonary exacerbations were compared during the time intervals they developed serological evidence of infection to their non-infection intervals. Results: Six of 44 CF children had a virus positive respiratory illness in 56 LTRI events and 18 hospitalizations. Serological evidence of hMPV and RSV infections occurred in 16 and 20 CF children, respectively; 8 had infections with both viruses. A greater proportion of CF children had ,1 LRTI during their infection intervals compared to their non-infection intervals (13/25 vs. 5/25; P,=,0.03). A trend for higher rates of LRTI was observed in the infection intervals compared to non-infection intervals (9.5,±,11.0 vs. 4.2,±,9.9 per 1,000 child-days; P,=,0.06), and it was significantly greater with a more conservative estimate (one event per child per interval; 7.4,±,7.7 vs. 2.6,±,5.4 per 1,000 child-days; P,,0.01). No differences in hospitalizations rates were detected. Conclusion: The infection rates and clinical impact observed for hMPV were comparable to that for RSV in CF children 7,18 years of age. Pediatr Pulmonol. 2007; 42:66,74. © 2006 Wiley-Liss, Inc. [source] Culvert Replacement and Stream Habitat Restoration: Implications from Brook Trout Management in an Appalachian Watershed, U.S.A.RESTORATION ECOLOGY, Issue 3 2009Ira O. Poplar-Jeffers Abstract Large-scale culvert replacement programs could benefit migratory fish populations by reconnecting reproductive and foraging habitats in fragmented watersheds. The objectives of this study were to: (1) identify stream and culvert characteristics contributing to fish passage barriers within an Appalachian watershed, U.S.A.; (2) quantify the total amount of Brook trout (Salvelinus fontinalis) reproductive habitat isolated above culverts; and (3) use an ecological currency to identify culvert replacement priorities and stream mitigation credit opportunities. We surveyed 120 state-owned culverts and used a fish passage assessment filter to determine the "passability" of each culvert. We then constructed a geographic information system stream network model to quantify the amount of trout reproductive habitat isolated by culverts. Ninety-seven percent of surveyed culverts were classified as obstacles or complete barriers to trout dispersal. Culvert impassability was higher in small streams with slopes exceeding 3,5%, suggesting a direct relationship between slope and impassability. Thirty-three percent of Brook trout reproductive habitat, representing over 200 km of stream, was isolated by culverts. This is a conservative estimate, because we did not survey privately or federally owned culverts. The top 20 prioritized culverts accounted for nearly half of the habitat loss. Our results indicate that standard culvert designs placed in streams with slopes exceeding 5% consistently produce trout dispersal barriers and should be avoided during new road construction. The process developed here provides an efficient method for identifying culvert replacement priorities and may be used to maximize watershed scale benefits of stream restoration. [source] Using Telemedicine to Avoid Transfer of Rural Emergency Department PatientsTHE JOURNAL OF RURAL HEALTH, Issue 3 2001Lanis L. Hicks Ph.D ABSTRACT: Access to emergency treatment in rural areas can often mean the difference between life and death. Telemedicine technologies have the potential of providing earlier diagnosis and intervention, of saving lives and of avoiding unnecessary transfers from rural hospital emergency departments to urban hospitals. This study examined the hypothetical impact of telemedicine services on patients served by the emergency departments of two rural Missouri liospitals and the potential financial impact on the affected hospitals. Of the 246 patients transferred to the hub hospital from the two facilities during 1996, 161 medical records (65.4 percent) were analyzed. Using a conservative approach, only 12 of these cases were identified as potentially avoidable transfers with the use of telemedicine. Of these 12, 5 were admitted to the hub hospital after transfer. In addition to this conservative estimate of avoidable transfers based on current availability of resources in the rural hospitals, two more aggressive scenarios were developed, based on an assumption of increased service availability in the rural hospitals. Economic multipliers were used to estimate the financial impacts on communities in each scenario. This evaluation study demonstrates the potential value of telemedicine use in rural emergency departments to patients, rural hospitals and rural communities. [source] Power of Genetic Association Studies with Fixed and Random Genotype FrequenciesANNALS OF HUMAN GENETICS, Issue 5 2010Julia Kozlitina Summary When estimating the power of genetic association studies, the allele and genotype frequencies are often assumed to be known, and the numbers of individuals with each genotype are set equal to their expectations under Hardy-Weinberg equilibrium. In fact, both allele and genotype frequencies are unknown and thus random. It has previously been suggested that ignoring uncertainty in these parameters could lead to inflated power expectations. To overcome the problem, one can average power estimates over the distributions of unknown frequencies. We investigate the power-averaging method and find that, despite the intuitive appeal, it may not improve accuracy in practice, while significantly increasing computational time. For a fixed allele frequency, we show that the amount of overestimation diminishes rapidly with sample size and is completely negligible for N > 200. For an unknown frequency, the result of averaging depends on the genetic model, and may not always provide a more conservative estimate of power. We explore the effect of uncertainty in the factors that determine statistical power of association studies and propose a more economical approach to the power analysis. [source] Obstetric-induced incontinence: A black hole of preventable morbidityAUSTRALIAN AND NEW ZEALAND JOURNAL OF OBSTETRICS AND GYNAECOLOGY, Issue 6 2006Michelle J. THORNTON Abstract There is a detailed literature comprising clinical and anorectal physiological studies linking faecal incontinence to vaginal delivery. Specific risk factors are high infant birthweight, forceps delivery and prolonged second stage of labour. The onset of symptoms may be delayed for many years. Faecal incontinence occurs in more than 10% of adult females and urinary incontinence in about a third of multiparous women. This places a very large economic burden on the Australian health system. A conservative estimate for overall management of incontinence would be in excess of $A700 million but the actual amount is unknown. Preventative measures for avoiding pelvic floor injuries need to be established, and safe obstetric practice needs to be redefined in the light of current knowledge about incontinence. Outcome measures for safe birthing should not only include infant and maternal mortality and infant morbidity, but should also include the long-term effects of vaginal delivery on the pelvic floor, particularly urinary and faecal incontinence. Several state reports and one federal senate report on safe birthing have been lacking in this area. The safety of birthing centres and home birthing needs to be examined to provide birthing mothers with complete and appropriate information about safety in order that they may consider their options. Appropriate Caesarean section rates for optimal birthing safety are unknown and need to be re-examined. Calls for overall reduction in Caesarean section rates in Australia are inappropriate and cannot be justified until the effects of pelvic floor injury are added to the overall assessment. [source] "Demographic Futures for Christianity and the World Religions"DIALOG, Issue 1 2004By Todd M. Johnson Abstract:, Since before 1970 Christian researchers have been tracking the massive demographic shift of Christianity to the Southern Hemisphere and noting the increasingly religious nature of populations around the world. At the same time, writers on the future of religion have been drawn to extreme portrayals of decline or revival of religion. However, the world's religious situation is replete with detailed information, drawn from enormous data collections on religious affiliation and questions about religion in government censuses. Quantitative tools, utilizing this information in the context of demography provide a more nuanced view of humankind's religious future. Demographic trends coupled with conservative estimates of conversions and defections envision over 80% of the world's population will continue to be affiliated with religions 200 years into the future. This religious future will have a profound influence on Christian theology, relations between religions, and the interaction between religion and politics. [source] Evaluation of simplified methods of analysis for structures with triple friction pendulum isolatorsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 1 2010Fabio Fadi Abstract Triple friction pendulum isolators, that exhibit behavior with amplitude-dependent strength and instantaneous stiffness, represent a new development in seismic isolation. The application of simplified methods of analysis for this type of seismically isolated structures requires development of tools of simplified analysis and demonstration of their accuracy. This paper describes these tools and presents validation studies based on a large number of nonlinear response history analysis results. It is shown that simplified methods of analysis systematically provide good and often conservative estimates of isolator displacement demands and good estimates of isolator peak velocities. Copyright © 2009 John Wiley & Sons, Ltd. [source] A vector-valued ground motion intensity measure consisting of spectral acceleration and epsilonEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 10 2005Jack W. Baker Abstract The ,strength' of an earthquake ground motion is often quantified by an Intensity Measure (IM), such as peak ground acceleration or spectral acceleration at a given period. This IM is used to predict the response of a structure. In this paper an intensity measure consisting of two parameters, spectral acceleration and epsilon, is considered. The IM is termed a vector-valued IM, as opposed to the single parameter, or scalar, IMs that are traditionally used. Epsilon (defined as a measure of the difference between the spectral acceleration of a record and the mean of a ground motion prediction equation at the given period) is found to have significant ability to predict structural response. It is shown that epsilon is an indicator of spectral shape, explaining why it is related to structural response. By incorporating this vector-valued IM with a vector-valued ground motion hazard, we can predict the mean annual frequency of exceeding a given value of maximum interstory drift ratio, or other such response measure. It is shown that neglecting the effect of epsilon when computing this drift hazard curve leads to conservative estimates of the response of the structure. These observations should perhaps affect record selection in the future. Copyright © 2005 John Wiley & Sons, Ltd. [source] Exposure assessment of 17,-ethinylestradiol in surface waters of the United States and Europe,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2009Robert Hannah Abstract An evaluation of measured and predicted concentrations of 17,-ethinylestradiol in surface waters of the United States and Europe was conducted to develop expected long-term exposure concentrations for this compound. Measured environmental concentrations (MECs) in surface waters were identified from the literature. Predicted environmental concentrations (PECs) were generated for European and U.S. watersheds using the GREAT-ER and PhATEÔ models, respectively. The majority of MECs are nondetect and generally consistent with model PECs and conservative mass balance calculations. However, the highest MECs are not consistent with concentrations derived from conservative (worst-case) mass balance estimates or model PECs. A review of analytical methods suggests that tandem or high-resolution mass spectrometry methods with extract cleanup result in lower detection limits and lower reported concentrations consistent with model predictions and bounding estimates. Based on model results using PhATE and GREAT-ER, the 90th-percentile low-flow PECs in surface water are approximately 0.2 and 0.3 ng/L for the United States and Europe, respectively. These levels represent conservative estimates of long-term exposure that can be used for risk assessment purposes. Our analysis also indicates that average concentrations are one to two orders of magnitude lower than these 90th-percentile estimates. Higher reported concentrations (e.g., greater than the 99th-percentile PEC of ,1 ng/L) could result from methodological problems or unusual environmental circumstances; however, such concentrations are not representative of levels generally found in the environment, warrant special scrutiny, and are not appropriate for use in risk assessments of long-term exposures. [source] Uptake of inorganic chemicals from soil by plant leaves: Regressions of field data,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2001Rebecca A. Efroymson Abstract The estimation of chemical concentrations in wildlife foods, such as plant foliage, is often performed for risk assessments at contaminated sites. Regression models and uptake factors for use in estimating the uptake of inorganic elements from soil by above-ground plant tissues were derived in this study. These included models for arsenic, cadmium, copper, lead, mercury, nickel, selenium, and zinc. Models were developed using published data from soil contaminated in the field and were validated using measured concentrations from two contaminated sites. Single-variable regression models of log-transformed concentrations in plants versus log-transformed concentrations in soil are generally recommended over simple uptake factors for use in estimating plant uptake of inorganic contaminants in ecological risk assessments. Multiple regression models with soil concentration and pH as the variables are also recommended for estimating the uptake of four chemicals (cadmium, mercury, selenium, and zinc) by plants. Models for use in screening risk assessments, i.e., the upper 95% prediction limits on the regressions, are recommended to provide conservative estimates of uptake of inorganic chemicals by plants. [source] The benefits of switching smoking cessation drugs to over-the-counter statusHEALTH ECONOMICS, Issue 5 2002Theodore E. Keeler This paper provides an analysis of the benefits to society from the conversion of nicotine replacement drugs (nicotine patches and gum) in 1996 from sale by prescription only in the United States to over-the-counter (OTC) sales. To estimate these benefits, we first estimate statistical demand functions for nicotine patches and gum. Second, we calculate the effects of OTC conversion on sales of each type of nicotine replacement drug. Third, we survey the literature on the effects of nicotine replacement drugs on total quits of cigarette smoking. Fourth, we survey the literature on the effects of quits achieved on expected lifespan, and on the estimated monetary value of longer lives from smoking cessation. Finally, we use all this evidence to calculate the value of the social benefits of the OTC conversion to the US. As a result of the OTC conversion, consumption of nicotine replacement drugs has increased substantially, by 78,92% for nicotine patches and 180% for nicotine gum. We estimate that the resulting increase in smoking cessation generated annual net social benefits of the order of magnitude of $1.8,2 billion, based on conservative estimates both of the number of quits achieved and the value of added quality-adjusted life years from the reduced smoking. Copyright © 2002 John Wiley & Sons, Ltd. [source] Effect of number of fractionating trays on reactive distillation performanceAICHE JOURNAL, Issue 12 2000Muhammad A. Al-Arfaj Sneesby et al. recently suggested that adding trays in the stripping and rectifying sections of a reactive distillation column can degrade performance. This effect, if true, is not only counterintuitive, but very disturbing because it suggests that the design of reactive distillation columns cannot use conservative estimates of tray numbers, that is, we cannot simply add excess trays, as in conventional distillation. The problem is compounded by the uncertainty in vapor,liquid equilibrium data and tray efficiencies. This implies that developing reactive distillation columns would require extensive experimental work at the pilot-plant and plant stages to find the numbers of stages offering the best performance. Such a scenario would mean long and expensive development programs. This article explores the effect of the number of trays in the rectifying and/or stripping sections of reactive (catalytic) distillation columns. Three reactive distillation systems are used: an ideal hypothetical system, the ETBE system, and the methyl acetate system. Contrary to the published results, it is demonstrated that additional trays do not degrade performance. Two degrees of freedom available in all cases must be carefully chosen for fair comparisons. [source] Galaxy redshift surveys selected by neutral hydrogen using the Five-hundred metre Aperture Spherical TelescopeMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008Alan R. Duffy ABSTRACT We discuss the possibility of performing a substantial spectroscopic galaxy redshift survey selected via the 21-cm emission from neutral hydrogen using the Five-hundred metre Aperture Spherical Telescope (FAST) to be built in China. We consider issues related to the estimation of the source counts and optimizations of the survey, and discuss the constraints on cosmological models that such a survey could provide. We find that a survey taking around two years could detect ,107 galaxies with an average redshift of ,0.15 making the survey complementary to those already carried out at optical wavelengths. These conservative estimates have used the z= 0 H i mass function and have ignored the possibility of evolution. The results could be used to constrain ,=,mh to 5 per cent and the spectral index, ns, to 7 per cent independent of cosmic microwave background data. If we also use simulated power spectra from the Planck satellite, we can constrain w to be within 5 per cent of ,1. [source] | ||||||||||||||||||||||