Limited Applicability (limited + applicability)

Distribution by Scientific Domains

Selected Abstracts

Acute toxicity of heavy metals to acetate-utilizing mixed cultures of sulfate-reducing bacteria: EC100 and EC50

Vivek P. Utgikar
Abstract Acid mine drainage from abandoned mines and acid mine pit lakes is an important environmental concern and usually contains appreciable concentrations of heavy metals. Because sulfate-reducing bacteria (SRB) are involved in the treatment of acid mine drainage, knowledge of acute metal toxicity levels for SRB is essential for the proper functioning of the treatment system for acid mine drainage. Quantification of heavy metal toxicity to mixed cultures of SRB is complicated by the confounding effects of metal hydroxide and sulfide precipitation, biosorption, and complexation with the constituents of the reaction matrix. The objective of this paper was to demonstrate that measurements of dissolved metal concentrations could be used to determine the toxicity parameters for mixed cultures of sulfate-reducing bacteria. The effective concentration, 100% (EC100), the lowest initial dissolved metal concentrations at which no sulfate reduction is observed, and the effective concentration, 50% (EC50), the initial dissolved metal concentrations resulting in a 50% decrease in sulfate reduction, for copper and zinc were determined in the present study by means of nondestructive, rapid physical and chemical analytical techniques. The reaction medium used in the experiments was designed specifically (in terms of pH and chemical composition) to provide the nutrients necessary for the sulfidogenic activity of the SRB and to preclude chemical precipitation of the metals under investigation. The toxicity-mitigating effects of biosorption of dissolved metals were also quantified. Anaerobic Hungate tubes were set up (at least in triplicate) and monitored for sulfate-reduction activity. The onset of SRB activity was detected by the blackening of the reaction mixture because of formation of insoluble ferrous sulfide. The EC100 values were found to be 12 mg/L for copper and 20 mg/L for zinc. The dissolved metal concentration measurements were effective as the indicators of the effect of the heavy metals at concentrations below EC100. The 7-d EC50 values obtained from the difference between the dissolved metal concentrations for the control tubes (tubes not containing copper or zinc) and tubes containing metals were found to be 10.5 mg/L for copper and 16.5 mg/L for zinc. Measurements of the turbidity and pH, bacterial population estimations by means of a most-probable number technique, and metal recovery in the sulfide precipitate were found to have only a limited applicability in these determinations. [source]


Jeremy Glicksman
The quandary of Jewish women unable to remarry because of their husbands' refusal to grant them religious divorces is a real problem affecting real people. Husbands are wielding this lopsided power to "extort" money from their wives, obtain favorable child custody settlements, property settlements, and child support payments. The burgeoning divorce rate is certain to exacerbate this problem. Already, this situation has garnered international attention. In the wake of New York's legislative attempt to remedy this problem, countries, including the United Kingdom and Australia, have promulgated legislative solutions to this dilemma. New York is the only state in the United States to pass such a statute. Unfortunately, New York's statute is flawed because it is of limited applicability and still allows for situations in which the Jewish wife is civilly divorced but religiously married. This Note proposes amending New York's statute to make it applicable to any and all divorce proceedings and to any barrier to remarriage. This Note will further recommend that the proposed amended statute should be adopted worldwide. [source]

Tensile and compressive damage coupling for fully-reversed bending fatigue of fibre-reinforced composites

W. Van Paepegem
ABSTRACT Due to their high specific stiffness and strength, fibre-reinforced composite materials are winning through in a wide range of applications in automotive, naval and aerospace industry. Their design for fatigue is a complicated problem and a large research effort is being spent on it today. However there is still a need for extensive experimental testing or large safety factors to be adopted, because numerical simulations of the fatigue damage behaviour of fibre-reinforced composites are often found to be unreliable. This is due to the limited applicability of the theoretical models developed so far, compared to the complex multi-axial fatigue loadings that composite components often have to sustain in in-service loading conditions. In this paper a new phenomenological fatigue model is presented. It is basically a residual stiffness model, but through an appropriate choice of the stress measure, the residual strength and thus final failure can be predicted as well. Two coupled growth rate equations for tensile and compressive damage describe the damage growth under tension,compression loading conditions and provide a much more general approach than the use of the stress ratio R. The model has been applied to fully-reversed bending of plain woven glass/epoxy specimens. Stress redistributions and the three stages of stiffness degradation (sharp initial decline , gradual deterioration , final failure) could be simulated satisfactorily. [source]

A Method for Evaluating Horizontal Well Pumping Tests

GROUND WATER, Issue 5 2004
David E. Langseth
Predicting the future performance of horizontal wells under varying pumping conditions requires estimates of basic aquifer parameters, notably transmissivity and storativity. For vertical wells, there are well-established methods for estimating these parameters, typically based on either the recovery from induced head changes in a well or from the head response in observation wells to pumping in a test well. Comparable aquifer parameter estimation methods for horizontal wells have not been presented in the ground water literature. Formation parameter estimation methods based on measurements of pressure in horizontal wells have been presented in the petroleum industry literature, but these methods have limited applicability for ground water evaluation and are based on pressure measurements in only the horizontal well borehole, rather than in observation wells. This paper presents a simple and versatile method by which pumping test procedures developed for vertical wells can be applied to horizontal well pumping tests. The method presented here uses the principle of superposition to represent the horizontal well as a series of partially penetrating vertical wells. This concept is used to estimate a distance from an observation well at which a vertical well that has the same total pumping rate as the horizontal well will produce the same drawdown as the horizontal well. This equivalent distance may then be associated with an observation well for use in pumping test algorithms and type curves developed for vertical wells. The method is shown to produce good results for confined aquifers and unconfined aquifers in the absence of delayed yield response. For unconfined aquifers, the presence of delayed yield response increases the method error. [source]

Relationship-based e-commerce: theory and evidence from China

Maris G. Martinsons
Abstract., Electronic commerce models and prescriptions from rule-based market economies like the United States have limited applicability in emerging markets. This paper adopts a strategic management perspective to examine the distinctive challenges facing e-commerce in China. A theory is developed to explain how the lack of dependable rules encourages guanxi and relationship-based commerce. It suggests that personal trust, contextual and informal information, and blurred boundaries between business and government have shaped e-commerce in mainland China. Case studies of online retailers in Beijing and Shanghai and a business-to-business (B2B) marketspace reveal how dynamic business relationships with complementary service providers and state agents can overcome institutional deficiencies. Short message service (SMS)-based mobile commerce (m-commerce) and other leapfrogging information technology (IT) applications could transform Chinese consumer behaviour and improve economic efficiency. The evidence from China helps to explain the influence of culture and institutions on different types of IT applications. Implications for e-commerce research and practice in China and other emerging markets are discussed. [source]

Prediction of human pharmacokinetics,gut-wall metabolism

Urban Fagerholm
Intestinal mucosal cells operate with different metabolic and transport activity, and not all of them are involved in drug absorption and metabolism. The fraction of these cells involved is dependent on the absorption characteristics of compounds and is difficult to predict (it is probably small). The cells also appear comparably impermeable. This shows a limited applicability of microsome intrinsic clearance (CLint)-data for prediction of gut-wall metabolism, and the difficulty to predict the gut-wall CL (CLGW) and extraction ratio (EGW). The objectives of this review were to evaluate determinants and methods for prediction of first-pass and systemic EGW and CLGW in man, and if required and possible, develop new simple prediction methodology. Animal gut-wall metabolism data do not appear reliable for scaling to man. In general, the systemic CLGW is low compared with the hepatic CL. For a moderately extracted CYP3A4-substrate with high permeability, midazolam, the gut-wall/hepatic CL-ratio is only 1/35. This suggests (as a general rule) that systemic CLGW can be neglected when predicting the total CL. First-pass EGW could be of importance, especially for substrates of CYP3A4 and conjugating enzymes. For several reasons, including those presented above and that blood flow based models are not applicable in the absorptive direction, it seems poorly predicted with available methodology. Prediction errors are large (several-fold on average; maximum-15-fold). A new simple first-pass EGW -prediction method that compensates for regional and local differences in absorption and metabolic activity has been developed. It has been based on human cell in-vitro CLint and fractional absorption from the small intestine for reference (including verapamil) and test substances, and in-vivo first-pass EGW -data for reference substances. First-pass EGW -values for CYP3A4-substrates with various degrees of gastrointestinal uptake and CLint and a CYP2D6-substrate were well-predicted (negligible errors). More high quality in-vitro CLint - and in-vivo EGW -data are required for further validation of the method. [source]

Confirmation and determination of carboxylic acids in root exudates using LC,ESI-MS

Zuliang Chen
Abstract Reversed-phase liquid chromatography with UV detection is of limited applicability in the separation and identification of carboxylic acids because of the column's poor separation efficiency and the non-selective nature of the UV detector. To address this issue, RP-LC with electrospray ionization mass spectrometry has been explored for the confirmation and determination of carboxylic acids in plant root exudates, with ESI-MS providing structural information, high selectivity, and high sensitivity. The separation of 10 carboxylic acids (pyruvic, lactic, malonic, maleic, fumaric, succinic, malic, tartaric, trans -aconitic, and citric acid) was performed on a C18 column using an eluent containing 0.1% (v/v) acetic acid within 10 min, where the acidic eluent not only suppressed the ionization of the carboxylic acids to be retained on the column, but was also compatible with ESI-MS detection. In addition, an additional standard was used to overcome the matrix effect. The results showed that peak areas correlated linearly with the concentration of carboxylic acids over the range 0.05,10 mg/L. The detection limits of target acids (signal-to-noise S/N ratio of 3) ranged from 20 to 30 ,g/L. Finally, the proposed method was used for the confirmation and determination of low-molecular-weight carboxylic acids in plant root exudates, and provided a simple analytical procedure, including sample processing, fast separation, and high specificity and sensitivity. [source]

How and why do college students use Wikipedia?

Sook Lim
The purposes of this study were to explore college students' perceptions, uses of, and motivations for using Wikipedia, and to understand their information behavior concerning Wikipedia based on social cognitive theory (SCT). A Web survey was used to collect data in the spring of 2008. The study sample consisted of students from an introductory undergraduate course at a large public university in the midwestern United States. A total of 134 students participated in the study, resulting in a 32.8% response rate. The major findings of the study include the following: Approximately one-third of the students reported using Wikipedia for academic purposes. The students tended to use Wikipedia for quickly checking facts and finding background information. They had positive past experiences with Wikipedia; however, interestingly, their perceptions of its information quality were not correspondingly high. The level of their confidence in evaluating Wikipedia's information quality was, at most, moderate. Respondents' past experience with Wikipedia, their positive emotional state, their disposition to believe information in Wikipedia, and information utility were positively related to their outcome expectations of Wikipedia. However, among the factors affecting outcome expectations, only information utility and respondents' positive emotions toward Wikipedia were related to their use of it. Further, when all of the independent variables, including the mediator, outcome expectations, were considered, only the variable information utility was related to Wikipedia use, which may imply a limited applicability of SCT to understanding Wikipedia use. However, more empirical evidence is needed to determine the applicability of this theory to Wikipedia use. Finally, this study supports the knowledge value of Wikipedia (Fallis, 2008), despite students' cautious attitudes toward Wikipedia. The study suggests that educators and librarians need to provide better guidelines for using Wikipedia, rather than prohibiting Wikipedia use altogether. [source]

Microsatellite DNA markers for the aphid parasitoid Lysiphlebus fabarum and their applicability to related species

Abstract The aphid parasitoid Lysiphlebus fabarum is suspected to form distinct, host-associated lineages and exhibits poorly understood variation in reproductive mode including thelytokous and arrhenotokous populations. As a tool to study these issues, we developed 11 polymorphic microsatellite markers. The observed number of alleles ranged from two to 35, and the observed heterozygosity ranged from 0.01 to 0.64. Cross-species amplification tests demonstrated their utility for several congeners, but revealed very limited applicability to more distantly related species. [source]

Changing views in Canadian geomorphology: are we seeing the landscape for the processes?

géomorphologie; révolution quantitative; formes du lit marin; éolien; transport des sédiments; dunes Geomorphology in Canada, as elsewhere, has evolved into an essentially bipartite discipline focusing either on ,process' or broader ,historical' (Quaternary) landscape interpretation. A growing emphasis on process-oriented research that relies increasingly on instrumentation and computational technologies has occurred. Critics of such research note limited applicability for landscape evolution, fashionability of methods and limited societal relevance. Indeed, some say we are not seeing the landscape for the processes. This article discusses the changing nature of geomorphology since the Quantitative Revolution of the 1950s including new advances, recent trends and challenges. Publication trends and recent advances suggest that the discipline is very healthy (following a slump in the early 1990s) and continues to evolve, which may reflect increasing research infrastructure and/or funding opportunities and new publications spotlighting Canadian research. Unfortunately, fundamental (less applied) research is threatened by funding program shifts, changing institutional pressures and a decline in research capacity from retirement attrition, and student recruitment challenges. Three research priorities are recommended: (1) continued fundamental research, (2) more integrated modelling to link micro scale processes to macro scale landform behaviour and(3) improvements in profiling our discipline amongst students and related professionals. L'évolution des perspectives de la géomorphologie canadienne : les processus occultent-ils le paysage? Le caractère bipartite que revêt aujourd'hui la géomorphologie au Canada, comme partout ailleurs dans le monde, marque l'aboutissement de l'évolution d'une discipline axée soit sur les «processus», soit sur une interprétation élargie et «historique» (quaternaire) du paysage. De plus en plus, la recherche porte sur les processus et s'inscrit dans le cadre du développement des technologies d'instrumentation et informatique. Plusieurs ont critiqué cette approche de recherche en soulignant ses limites pour étudier l'évolution des paysages, l'effet de mode des méthodes, et la faiblesse de son apport à la société. Certains vont jusqu'à dire que les processus nous cachent la vue du paysage. Cet article traite du caractère évolutif de la géomorphologie depuis les années 1950 quand les bases de la révolution quantitative ont étéétablies. La discussion porte entre autres sur le progrès des connaissances, les dernières tendances et les défis à relever. Les tendances en matière de publication et l'avancement des connaissances laissent croire que la discipline se porte bien (malgré un ralentissement au début des années 1990) et suit une trajectoire évolutive. Il est possible qu'une telle situation soit le reflet del'accroissement des capacités de recherche et/ou du financement et des nouvelles publications mettant en évidence les résultats de recherches canadiennes. Malheureusement, les modifications apportées aux programmes de subvention, les différentes pressions exercées par les institutions, la baisse de régime en matière de recherche causée par les départs à la retraite, et les défis pour assurer la relève universitaire constituent une menace pour la recherche fondamentale (c'est-à-dire moins appliquée). C'est dans cette foulée que trois chantiers de recherche sont proposés : (1) poursuivre la recherche fondamentale, (2) élaborer des modèles plus intégrés qui conjuguent les processus à l'échelle micro et les comportements des formes de relief, et (3) procéder à des améliorations du profilage des étudiants et des professionnels apparentés. [source]

Apomorphine sublingual as primary or secondary treatment for erectile dysfunction in patients with spinal cord injury

R.T. Strebel
OBJECTIVES To evaluate the effectiveness of apomorphine sublingual (SL) 3 mg, as a primary or secondary treatment for erectile dysfunction (ED) in patients with spinal cord injury (SCI), and to determine possible differences in efficacy considering clinical, urodynamic and neurophysiological findings. PATIENTS AND METHODS The study included 22 patients with chronic SCI and neurogenic ED who were examined physically and by a video-urodynamic evaluation. A neurophysiological evaluation included somatosensory evoked potentials of the pudendal nerve, palmar and plantar sympathetic skin responses and bulbocavernous reflex recordings. Thereafter the patients received 8 tablets of apomorphine SL 3 mg and were asked to complete the International Index of Erectile Function questionnaire before and after treatment. Side-effects, subjective efficacy compared with other treatments and satisfaction with the SL administration were recorded. RESULTS Of the 22 men, 11 had upper motor neurone lesions (six complete, five incomplete), eight lower motor neurone lesions (seven complete, one incomplete) and three had mixed lesions. In all, 12 patients took sildenafil citrate and five alprostadil intracavernosally beforehand, and five had used nothing to treat their ED. Seven patients had some response and reported that the drug helped them to obtain an erection, but only two reported erections sufficient for intercourse and would agree to continue apomorphine SL as their standard treatment; all the others reported being disappointed. Nine patients reported side-effects. There were no significant correlations for electrophysiological or urodynamic findings and treatment success. Of the 22 patients 20 preferred SL rather than the normal administration. CONCLUSIONS Apomorphine SL, a D1/D2 dopamine agonist, facilitates erectile function in a heterogeneous group of patients with no significant relationship with any of the assessed urodynamic or electrophysiological variables. The overall low rates of response either for primary or secondary treatment suggests that apomorphine will have limited applicability in patients with SCI. [source]

Serum levels of interferon-,, tumour necrosis factor-,, soluble interleukin-6R and soluble cell activation markers for monitoring response to treatment of leprosy reactions

A. Iyer
Summary Identifying pathogen and host-related laboratory parameters are essential for the early diagnosis of leprosy reactions. The present study aimed to clarify the validity of measuring the profiles of serum cytokines [interleukin (IL)-4, IL-6, IL-10, interferon (IFN)-, and tumour necrosis factor (TNF)-,], the soluble IL-6 receptor (sIL-6R), soluble T cell (sCD27) and macrophage (neopterin) activation markers and Mycobacterium leprae -specific anti-PGL-I IgM antibodies in relation to the leprosy spectrum and reactions. Serum samples from 131 Indonesian leprosy patients (82 non-reactional leprosy patients and 49 reactional) and 112 healthy controls (HC) from the same endemic region were investigated. Forty-four (89·8%) of the reactional patients had erythema nodosum leprosum (ENL) while only five (10·2%) had reversal reaction (RR). Follow-up serum samples after corticosteroid treatment were also obtained from 17 of the patients with ENL and one with RR. A wide variability in cytokine levels was observed in the patient groups. However, IFN-, and sIL-6R were elevated significantly in ENL compared to non-ENL patients. Levels of IFN-,, TNF-, and sIL-6R declined significantly upon corticosteroid treatment of ENL. Thus, although the present study suggests limited applicability of serial measurement of IFN-,, TNF-, and sIL-6R in monitoring treatment efficacy of ENL, reactions it recommends a search for a wider panel of more disease-specific markers in future studies. [source]