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Practical Utility (practical + utility)

Distribution by Scientific Domains

Medical Sciences	37%
Chemistry	16%
Mathematics and Statistics	12%
Business, Economics, Finance and Accounting	12%
4 Other Domains	23%

Selected Abstracts

The Reliability, Validity and Practical Utility of Measuring Supports using the I-CAN Instrument: Part II

JOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES, Issue 4 2009
Vivienne C. Riches
Background, There is an urgent need for developing reliable, valid and practical instruments that assess and classify the support needed by persons with disability to function in their chosen living, working and social environments. I-CAN is an instrument that addresses the frequency and level of support needed (not individual skills or deficits) for each individual with a disability. Method, Studies were conducted to assess the test,retest reliability and inter-rater reliability. Concurrent validity was investigated by exploring the relationship between the I-CAN domain scales and the Inventory for Client and Agency Planning (ICAP) (Bruininks et al. 1986) and the Quality of Life Questionnaire (QOL-Q) (Schalock & Keith 1993). Predictive validity studies were undertaken using day- and night-time support hours. Regression analyses were run using these measures with I-CAN domain scales. Two independent studies were also conducted to ascertain the practical utility of the instrument. Results, The I-CAN instrument demonstrated excellent inter-rater and test,retest reliability in the Activities and Participation domains. Low-to-moderate test,retest results in Physical Health, Mental Emotional Health and Behaviour domains were tracked to actual change in support needs in these areas. Validity proved acceptable. The relationships between I-CAN domain scales and adaptive behaviour were mixed but in the expected direction. Low-to-moderate correlation coefficients were evident between the I-CAN scales and the QOL-Q Total, but greater support needed in certain domains was associated with less empowerment and independence, and less community integration and social belonging. Attempts to explain current support hours against the I-CAN scales were disappointing and suggest that a number of other factors apart from individual support need to play a significant role. There was general satisfaction with the assessment process from stakeholders and participant groups. Conclusions, I-CAN is a reliable, valid and user-friendly instrument for assessing the support needs of people with disabilities. It uses a process that involves the persons with disability, their family and friends and staff as appropriate. It is also apparent that the current provision of paid support hours by agencies is a complex phenomenon that is not based solely on individual support needs. Further research is warranted on the influence of the environment and the perceptions of need for support based on negotiable and non-negotiable support needs. [source]

Quantitative LC/MS/MS method and in vivo pharmacokinetic studies of vitexin rhamnoside, a bioactive constituent on cardiovascular system from hawthorn

BIOMEDICAL CHROMATOGRAPHY, Issue 4 2007
Mingjin Liang
Abstract A simple and accurate liquid chromatography coupled with tandem mass spectrometry method was developed for determination and in vivo pharmacokinetic studies of vitexin rhamnoside in rat plasma. After protein precipitation using methanol, the analytes were separated by a Luna C18 column with an isocratic elution and analyzed by mass spectrometry in multiple reaction monitoring mode using the respective negative ion at m/z 577.2,293.0 for vitexin rhamnoside and m/z 593.2,413.0 for internal standard (IS) vitexin glucoside. The method was validated systematically within the concentration range 5,5000 µg/L (R > 0.996) and the lower limit of quantitation was 5 µg/L. Acceptable precision and accuracy were acquired for concentrations over the standard curve range. It was further applied to assess pharmacokinetics and bioavailability of vitexin rhamnoside after intravenous and oral administration to rats. The oral bioavailability of vitexin rhamnoside was only 3.57%, which indicated that vitexin rhamnoside had poor absorption or underwent extensive first-pass metabolism. Practical utility of this new LC/MS/MS method was confirmed in pilot pharmacokinetic studies in rats following both intravenous and oral administration. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Forehead Donor Site Full-Thickness Skin Graft

DERMATOLOGIC SURGERY, Issue 3 2005
Vassilios Dimitropoulos MD
Background Full-thickness skin grafts (FTSGs) are useful for reconstructing nasal defects. Traditional reported donor sites include the preauricular, postauricular, supraclavicular, clavicular, conchal bowl, melolabial fold, and upper eyelid skin. Selection of the "best" donor site is based on the "best" tissue match and ability to camouflage the donor scar. Objective The purpose was to report our experience with FTSGs harvested from the forehead for reconstruction of nasal defects following Mohs' surgery. Methods A retrospective query of the Mohs' surgery database was performed to identify nasal defects repaired with a FTSG harvested from the forehead skin. The research record contained the patient age and gender, defect size, and cosmetic and functional outcomes interpreted by the patient and surgeon. Results FTSGs from forehead skin were used to repair the nasal defects in three patients. The functional and cosmetic outcome of all three cases was deemed excellent by the patient and surgeon. Donor site scars were well concealed within preexisting rhytids. Conclusion FTSGs harvested from the forehead, although limited in practical utility, may offer an optimal FTSG match for limited select defects while also providing an easily camouflaged donor site scar within a forehead rhytid. VASSILIOS DIMITROPOULOS, MD, CHRISTOPHER K. BICHAKJIAN, MD, AND TIMOTHY M. JOHNSON, MD, HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS. [source]

High-sensitive determination of human ,-thrombin by its 29-mer aptamer in affinity probe capillary electrophoresis

ELECTROPHORESIS, Issue 12 2008
Yilin Li
Abstract ACE technique provides an effective tool for the separation and identification of disease-related biomarkers in clinical analysis. In recent years, a couple of synthetic DNA or RNA oligonucleotides, known as aptamers, rival the specificity and affinity for targets to antibodies and are employed as one kind of powerful affinity probe in ACE. In this work, based on high affinity between antithrombin aptamer and thrombin (their dissociation constant is 0.5,nM), a carboxyfluorescein-labeled 29-nucleotide (nt) aptamer (F29-mer) was used and an aptamer-based affinity probe CE (aptamer-based APCE) method was successfully established for high-sensitive detection and quantitative analysis of thrombin. Experimental conditions including incubation temperature and time, buffer composition, and concentration of cations were investigated and optimized. Under the optimized condition, the linear range was from 0 to 400,nM and the LOD was 2,nM (74,ng/mL, S/N,=,3), i.e., 40,amol, both in running buffer and in 5% v/v human serum. This LOD is the lowest one than those achieved by the previous APCE methods but based on a 15-mer aptamer. This approach offers a promising method for the rapid, selective, and sensitive detection of thrombin in practical utility. Further binding experiments using one carboxyfluorescein-labeled aptamer and the other nonlabeled aptamer or vice versa were carried out to deduce the formation of ternary complex when these two aptamers coexisted in the free solution with thrombin. [source]

Random Copolymer Films with Molecular-Scale Compositional Heterogeneities that Interfere with Protein Adsorption

ADVANCED FUNCTIONAL MATERIALS, Issue 21 2009
Salmaan H. Baxamusa
Abstract Smooth surfaces with compositional heterogeneities at a molecular-length scale are presented with the goal of disrupting surface,protein interactions. These surfaces are synthesized by utilizing photoinitiated chemical vapor deposition (piCVD) to deposit thin films of random copolymers consisting of highly hydrophilic and highly hydrophobic comonomers. Swellability, wettability, and surface roughness could be systematically controlled by tuning the copolymer composition. The surface composition was dynamic, and the surface reconstructed based on the hydration state of the film. Proteins adsorbed to the copolymer films less readily than to either of the respective homopolymers, indicating a synergistic effect resulting from the random copolymer presenting molecular-scale compositional heterogeneity. These results provide direct evidence that protein adsorption can be disrupted by such surfaces and a simple analytical model suggests that the heterogeneities occur over areas encompassing 4,5 repeat units of the polymer. The synthetic method used to create these films can be used to coat arbitrary geometries, enabling practical utility in a number of applications. [source]

Tris(4-cyanophenyl)amine: Simple Synthesis via Self-assembly; Strong Fluorescence in Solution, Nano/microcrystals, and Solid,

ADVANCED FUNCTIONAL MATERIALS, Issue 13 2007
A. Patra
Abstract The threefold symmetric molecule, tris(4-cyanophenyl)amine (TCPA) is synthesized from 4-fluorocyanobenzene by treatment with potassium carbonate in dimethylsulfoxide; the occurrence of the reaction without any amine reagent suggests the involvement of a novel self-assembly process. A reprecipitation strategy provides stable colloids containing highly monodisperse nano/microcrystals with well-defined cubic morphology and sizes tunable from 250 to 500,nm. The solution, colloid, and solid states of TCPA exhibit strong blue fluorescence; the colloid shows dual emission with an unusually small Stokes shift. Computational investigations are carried out on the molecule and supramolecular assemblies derived from the crystal structure. Coupled with detailed spectroscopic studies, they show that the emission in the colloidal and solid states can be attributed to energy levels resulting from the intermolecular interactions within different aggregation motifs in the condensed phase and energy cascades between them. The computations also reveal the presence of cooperative interactions in the molecular crystal contributing to its high thermal stability. The strong light emission exhibited by TCPA, concurrently in the solution, nano/microcrystal, and solid states establishes it as a novel molecular material of potential practical utility; it has led to the exploration of the underlying mechanism that describes the phenomena observed in the different physical states. [source]

Current modalities and new advances in the treatment of basal cell carcinoma

INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 5 2006
Roger I. Ceilley MD
Basal cell carcinoma (BCC) is one of the most common cancers. Surgical extirpation is currently the standard of care for BCC, which is associated with several advantages and disadvantages. Procedures such as surgical excision used to treat superficial BCC (sBCC) and nodular BCC (nBCC) may have high 5-year recurrence rates if tumors are not completely excised. Curettage with electrodesiccation is a common method for treating primary BCC. However, multiple cycles are recommended and the procedure can have unsatisfactory cosmetic results (e.g. scarring and hypopigmentation). Mohs micrographic surgery has a low rate of disease recurrence but is a specialized procedure usually limited to specific indications (e.g. high-risk tumors). Cryosurgery and photodynamic therapy require multiple cycles and are associated with variable cosmetic outcomes and recurrence rates. As with any procedure, potential risks and patient quality-of-life issues need to be considered. In addition, substantial patient and healthcare provider inconvenience limit the practical utility of some modalities. Pharmacologic interventions provide another treatment option as adjunctive or monotherapy. Investigations of imiquimod, a novel immune response modifier, have indicated that this topical, noninvasive agent is safe and well tolerated and may be efficacious in the treatment of BCC. This review will highlight the role of standard treatment modalities and introduce new advances in the treatment of BCC. [source]

What do People Want from their Jobs?

INTERNATIONAL JOURNAL OF SELECTION AND ASSESSMENT, Issue 1 2010
The Big Five, core self-evaluations, work motivation
If people are differentially motivated on the basis of individual differences, this implies important practical consequences with respect to staffing decisions and the selection of the right motivational techniques for managers. In two different samples (students facing graduation vs full-time employees), the relationships between personality traits and the preference for job characteristics concerning either extrinsic (job environment) or intrinsic job features (work itself) were investigated. Two personality traits [openness to experience and core self-evaluations (CSE)] were consistently found to be positively related to the preference concerning work characteristics, and CSE showed incremental validity with regard to intrinsic work motivation factors (e.g., experienced meaningfulness, autonomy). Furthermore, age was differentially linked to those job characteristics. The results are discussed with regards to the optimal Person,Job Fit and the practical utility of the personality constructs. [source]

The Reliability, Validity and Practical Utility of Measuring Supports using the I-CAN Instrument: Part II

Should Actuarial Risk Assessments be Used with Sex Offenders who are Intellectually Disabled?

JOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES, Issue 4 2004
Andrew J. R. Harris
Background, Objective actuarial assessments are critical for making risk decisions, determining the necessary level of supervision and intensity of treatment (Andrews & Bonta 2003). This paper reviews the history of organized risk assessment and discusses some issues in current attitudes towards sexual offenders with intellectual disabilities. Method, We present two risk assessment tools (RRASOR and STABLE-2000) that appear to have practical utility with this population. Data are presented from a community sample of 81 sexual offenders who are intellectually disabled suggesting that the RRASOR may provide a useful metric of risk for this population. Dynamic risk is assessed using the STABLE-2000. This tool, based on 16 areas empirically associated with sexual recidivism, samples the individuals' current behaviour, skill deficits and personality factors. Change in these factors serves to flag the supervisor to changing risk levels. Conclusions, In addressing the question of whether we should seek special risk measures normed on people with intellectually disabilities, given the current lack of alternative tools, we conclude that it is reasonable to make use of the risk assessments that have been validated on the general sex offender population. [source]

Infrared Microscopic Imaging of Bone: Spatial Distribution of CO32,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 5 2001
H. Ou-Yang
Abstract This article describes a novel technology for quantitative determination of the spatial distribution of CO32, substitution in bone mineral using infrared (IR) imaging at ,6 ,m spatial resolution. This novel technology consists of an IR array detector of 64 × 64 elements mapped to a 400 ,m × 400 ,m spot at the focal plane of an IR microscope. During each scan, a complete IR spectrum is acquired from each element in the array. The variation of any IR parameter across the array may be mapped. In the current study, a linear relationship was observed between the band area or the peak height ratio of the CO32, v3 contour at 1415 cm,1 to the PO43, v1,v3 contour in a series of synthetic carbonated apatites. The correlation coefficient between the spectroscopically and analytically determined ratios (R2 = 0.989) attests to the practical utility of this IR area ratio for determination of bone CO32, levels. The relationship forms the basis for the determination of CO32, in tissue sections using IR imaging. In four images of trabecular bone the average CO32, levels were 5.95 wt% (2298 data points), 6.67% (2040 data points), 6.66% (1176 data points), and 6.73% (2256 data points) with an overall average of 6.38 ± 0.14% (7770 data points). The highest levels of CO32, were found at the edge of the trabeculae and immediately adjacent to the Haversian canal. Examination of parameters derived from the phosphate v1,v3 contour of the synthetic apatites revealed that the crystallinity/perfection of the hydroxyapatite (HA) crystals was diminished as CO32, levels increased. The methodology described will permit evaluation of the spatial distribution of CO32, levels in diseased and normal mineralized tissues. [source]

Conducting suicide research in naturalistic clinical settings,

JOURNAL OF CLINICAL PSYCHOLOGY, Issue 4 2009
David A. Jobes
Abstract Unique challenges arise for clinical researchers designing studies focused on suicidal behaviors due to the inherently high-risk nature of such research. Traditional approaches to clinical trial design are briefly discussed, highlighting the limitations and obstacles of these approaches when working with suicidal individuals. Using their own personal experiences and setbacks from an ongoing clinical suicidology research program, the authors argue for greater emphasis on effectiveness and translational research designs conducted in naturalistic clinical settings to test the practical utility of empirically-supported treatments for suicidal behaviors, to gain new perspectives on suicidal individuals, and to better understand the nature of suicidal risk. © 2009 Wiley Periodicals, Inc. J Clin Psychol 65:1,14, 2009. [source]

Predicting and explaining the propensity to bid in online auctions: a comparison of two action-theoretical models

JOURNAL OF CONSUMER BEHAVIOUR, Issue 2 2006
Michael Bosnjak
The literature on the willingness to bid and the actual bidding behaviour of consumers in online auctions is currently dominated by approaches based on the economic decision-making and information processing paradigm and are primarily focused on what influences auction outcomes. To the best of our knowledge, no serious attempts have been undertaken to stringently test and compare existing models derived from an action-theoretical perspective to predict and explain consumers´ propensity to use online auctions as well as their actual usage. Two theoretical models seem most promising in this context: The Theory of Planned Behaviour (Ajzen I, 1985, 1991) and a derivative of the Theory of Reasoned Action (Fishbein M and Ajzen I, 1975) tailored towards using computer technologies, the Technology Acceptance Model (Davis FD, 1989). In both theories, intentions play a central role in predicting behaviour. The models differ in their descriptions of the factors that determine behavioural intentions. In the Theory of Planned Behaviour, attitudes towards the behaviour, perceived behavioural control and subjective norms are assumed to influence intentions. In contrast, the Technology Acceptance Model suggests that intentions and attitudes are influenced by the perceived usefulness of a certain technological tool to improve shopping productivity (e.g. by enabling the consumer to obtain a better price or save time) and the tools´ perceived ease of use. In principle, both theories can be used to predict and explain technology-dependent consumer behaviour, but which one is more suited to online auctions? We compared both theories in terms of their predictive power and their practical utility. Although both models explain the propensity to bid in online auctions very well, the Technology Acceptance Model provides more specific recommendations for facilitating the use of online auctions. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Heterogeneity in skin treated with low-frequency ultrasound

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2008
Joseph Kushner IV
Abstract Recent experimental evidence using colored, fluorescent permeants suggests that skin treated with low-frequency sonophoresis (LFS) is perturbed in a heterogeneous manner. Macroscopic and microscopic visualization studies, topical penetration studies, transdermal permeability studies, and skin electrical resistivity measurements have shown that discrete domains, referred to as localized transport regions (LTRs), which are formed during LFS treatment of the skin, possess greatly reduced barrier properties, and therefore exhibit increased permeant skin penetration, compared to the surrounding regions of LFS-treated skin. The transformation of LTR formation from a heterogeneous to a homogeneous phenomenon has the potential benefit of increasing the maximum level of transdermal permeability or of reducing the area of skin required to deliver a desired dose of drug transdermally. Future studies, aimed at elucidating both the mechanisms of LTR formation and the limits of nondamaging formation of LTRs in the skin, are required to incorporate these proposed improvements to enhance the efficacy and practical utility of low-frequency sonophoresis. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:4119,4128, 2008 [source]

So mechanical or routine: The not original in Feist

JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 4 2010
Julian Warner
The United States Supreme Court case of 1991, Feist Publications, Inc. v. Rural Tel. Service Co., continues to be highly significant for property in data and databases, but remains poorly understood. The approach taken in this article contrasts with previous studies. It focuses upon the "not original" rather than the original. The delineation of the absence of a modicum of creativity in selection, coordination, and arrangement of data as a component of the not original forms a pivotal point in the Supreme Court decision. The author also aims at elucidation rather than critique, using close textual exegesis of the Supreme Court decision. The results of the exegesis are translated into a more formal logical form to enhance clarity and rigor. The insufficiently creative is initially characterized as "so mechanical or routine." Mechanical and routine are understood in their ordinary discourse senses, as a conjunction or as connected by AND, and as the central clause. Subsequent clauses amplify the senses of mechanical and routine without disturbing their conjunction. The delineation of the absence of a modicum of creativity can be correlated with classic conceptions of computability. The insufficiently creative can then be understood as a routine selection, coordination, or arrangement produced by an automatic mechanical procedure or algorithm. An understanding of a modicum of creativity and of copyright law is also indicated. The value of the exegesis and interpretation is identified as its final simplicity, clarity, comprehensiveness, and potential practical utility. [source]

Sparse partial least squares regression for simultaneous dimension reduction and variable selection

JOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 1 2010
Hyonho Chun
Summary., Partial least squares regression has been an alternative to ordinary least squares for handling multicollinearity in several areas of scientific research since the 1960s. It has recently gained much attention in the analysis of high dimensional genomic data. We show that known asymptotic consistency of the partial least squares estimator for a univariate response does not hold with the very large p and small n paradigm. We derive a similar result for a multivariate response regression with partial least squares. We then propose a sparse partial least squares formulation which aims simultaneously to achieve good predictive performance and variable selection by producing sparse linear combinations of the original predictors. We provide an efficient implementation of sparse partial least squares regression and compare it with well-known variable selection and dimension reduction approaches via simulation experiments. We illustrate the practical utility of sparse partial least squares regression in a joint analysis of gene expression and genomewide binding data. [source]

Pseudomartingale estimating equations for modulated renewal process models

JOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 1 2009
Fengchang Lin
Summary., We adapt martingale estimating equations based on gap time information to a general intensity model for a single realization of a modulated renewal process. The consistency and asymptotic normality of the estimators is proved under ergodicity conditions. Previous work has considered either parametric likelihood analysis or semiparametric multiplicative models using partial likelihood. The framework is generally applicable to semiparametric and parametric models, including additive and multiplicative specifications, and periodic models. It facilitates a semiparametric extension of a popular parametric earthquake model. Simulations and empirical analyses of Taiwanese earthquake sequences illustrate the methodology's practical utility. [source]

Proteomics by FTICR mass spectrometry: Top down and bottom up

MASS SPECTROMETRY REVIEWS, Issue 2 2005
Bogdan Bogdanov
Abstract This review provides a broad overview of recent Fourier transform ion cyclotron resonance (FTICR) applications and technological developments relevant to the field of proteomics. Both the "bottom up" (peptide level) and "top down" (intact protein level) approaches are discussed and illustrated with examples. "Bottom up" topics include peptide fragmentation, the accurate mass and time (AMT) tag approach and dynamic range extension technology, aspects of quantitative proteomics measurements, post-translational modifications, and developments in FTICR operation software focused on peptide and protein identification. Topics related to the "top down" approach include various aspects of high mass measurements, protein tandem mass spectrometry, methods for the study of protein conformations, and protein complexes as well as advanced technologies that may become of practical utility in the coming years. Finally, early examples of the integration of both FTICR approaches to biomedical proteomics applications are presented, along with an outlook for future directions. © 2004 Wiley Periodicals, Inc., Mass Spec Rev 24:168,200, 2005 [source]

HEDGING STRATEGIES AND MINIMAL VARIANCE PORTFOLIOS FOR EUROPEAN AND EXOTIC OPTIONS IN A LÉVY MARKET

MATHEMATICAL FINANCE, Issue 4 2010
Wing Yan Yip
This paper presents hedging strategies for European and exotic options in a Lévy market. By applying Taylor's theorem, dynamic hedging portfolios are constructed under different market assumptions, such as the existence of power jump assets or moment swaps. In the case of European options or baskets of European options, static hedging is implemented. It is shown that perfect hedging can be achieved. Delta and gamma hedging strategies are extended to higher moment hedging by investing in other traded derivatives depending on the same underlying asset. This development is of practical importance as such other derivatives might be readily available. Moment swaps or power jump assets are not typically liquidly traded. It is shown how minimal variance portfolios can be used to hedge the higher order terms in a Taylor expansion of the pricing function, investing only in a risk-free bank account, the underlying asset, and potentially variance swaps. The numerical algorithms and performance of the hedging strategies are presented, showing the practical utility of the derived results. [source]

Moving beyond clarity: towards a thin, vague, and useful understanding of spirituality in nursing care

NURSING PHILOSOPHY, Issue 4 2010
John Swinton RMN RNMD BD PhD
Abstract Spirituality is a highly contested concept. Within the nursing literature, there are a huge range and diversity of definitions, some of which appear coherent whereas others seem quite disparate and unconnected. This vagueness within the nursing literature has led some to suggest that spirituality is so diverse as to be meaningless. Are the critics correct in asserting that the vagueness that surrounds spirituality invalidates it as a significant aspect of care? We think not. It is in fact the vagueness of the concept that is its strength and value. In this paper, we offer a critique of the general apologetic that surrounds the use of the language of spirituality in nursing. With the critics, we agree that the term ,spirituality' is used in endlessly different and loose ways. Similarly, we agree that these varied definitions may not refer to constant essences or objects within people or in the world. However, we fundamentally disagree that this makes spirituality irrelevant or of little practical utility. Quite the opposite; properly understood, the vagueness and lack of clarity around the term spirituality is actually a strength that has powerful political, social, and clinical implications. We develop an understanding of spirituality as a way of naming absences and recognizing gaps in healthcare provision as well as a prophetic challenge to some of the ways in which we practise health care within a secular and sometimes secularizing context such as the National Health Service. [source]

Estimation of the day-specific probabilities of conception: current state of the knowledge and the relevance for epidemiological research

PAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 2006
Courtney D. Lynch
Summary Conception, as defined by the fertilisation of an ovum by a sperm, marks the beginning of human development. Currently, a biomarker of conception is not available; as conception occurs shortly after ovulation, the latter can be used as a proxy for the time of conception. In the absence of serial ultrasound examinations, ovulation cannot be readily visualised leaving researchers to rely on proxy measures of ovulation that are subject to error. The most commonly used proxy measures include: charting basal body temperature, monitoring cervical mucus, and measuring urinary metabolites of oestradiol and luteinising hormone. Establishing the timing of the ovulation and the fertile window has practical utility in that it will assist couples in appropriately timing intercourse to achieve or avoid pregnancy. Identifying the likely day of conception is clinically relevant because it has the potential to facilitate more accurate pregnancy dating, thereby reducing the iatrogenic risks associated with uncertain gestation. Using data from prospective studies of couples attempting to conceive, several researchers have developed models for estimating the day-specific probabilities of conception. Elucidating these will allow researchers to more accurately estimate the day of conception, thus spawning research initiatives that will expand our current limited knowledge about the effect of exposures at critical periconceptional windows. While basal body temperature charting and cervical mucus monitoring have been used with success in field-based studies for many years, recent advances in science and technology have made it possible for women to get instant feedback regarding their daily fertility status by monitoring urinary metabolites of reproductive hormones in the privacy of their own homes. Not only are innovations such as luteinising hormone test kits and digital fertility monitors likely to increase study compliance and participation rates, they provide valuable prospective data that can be used in epidemiological research. Although we have made great strides in estimating the timing and length of the fertile window, more work is needed to elucidate the day-specific probabilities of conception using proxy measures of ovulation that are inherently subject to error. Modelling approaches that incorporate the use of multiple markers of ovulation offer great promise to fill these important data gaps. [source]

Bayesian nonparametric hierarchical modeling

BIOMETRICAL JOURNAL, Issue 2 2009
David B. Dunson
Abstract In biomedical research, hierarchical models are very widely used to accommodate dependence in multivariate and longitudinal data and for borrowing of information across data from different sources. A primary concern in hierarchical modeling is sensitivity to parametric assumptions, such as linearity and normality of the random effects. Parametric assumptions on latent variable distributions can be challenging to check and are typically unwarranted, given available prior knowledge. This article reviews some recent developments in Bayesian nonparametric methods motivated by complex, multivariate and functional data collected in biomedical studies. The author provides a brief review of flexible parametric approaches relying on finite mixtures and latent class modeling. Dirichlet process mixture models are motivated by the need to generalize these approaches to avoid assuming a fixed finite number of classes. Focusing on an epidemiology application, the author illustrates the practical utility and potential of nonparametric Bayes methods. [source]

Circulating biomarkers for vascular endothelial growth factor inhibitors in renal cell carcinoma,

CANCER, Issue S10 2009
Amado J. Zurita MD
Abstract In recent years, there has been significant progress in the clinical development and application of antiangiogenic therapies in renal cell carcinomas, particularly inhibitors of the vascular endothelial growth factor (VEGF) pathway. Despite this progress, no validated methods are currently available for identifying which patients are most likely to respond to treatment or experience toxic effects, selecting the optimal dose, or determining whether the intended molecular target has been effectively inhibited. However, recent studies have suggested that some of the biomarkers currently under investigation in clear cell renal cell carcinoma for VEGF pathway inhibitors are promising. These biomarkers include circulating proangiogenic factors and receptors; markers of hypoxia and endothelial damage; and cellular populations in peripheral blood, such as circulating endothelial cells. Further preclinical and translational validation studies are still needed to determine their practical utility in the clinical setting. Cancer 2009;115(10 suppl):2346-54. © 2009 American Cancer Society. [source]

Quinaphos and Dihydro-Quinaphos Phosphine,Phosphoramidite Ligands for Asymmetric Hydrogenation

CHEMISTRY - A EUROPEAN JOURNAL, Issue 25 2010
Thomas Pullmann Dr.
Abstract New derivatives of the Quinaphos ligands and the related Dihydro-Quinaphos ligands based on the more flexible 1,2,3,4-tetrahydroquinoline backbone have been prepared and fully characterised. A general and straightforward separation protocol was devised, which allowed for the gram-scale isolation of the Ra,Sc and Sa,Rc diastereomers. These new phosphine,phosphoramidite ligands have been applied in the Rh-catalysed asymmetric hydrogenation of functionalised olefins with the achievement of excellent enantioselectivities (,99,%) in most cases and turnover frequency (TOF) values of up to ,20,000,h,1. These results substantiate the practical utility of readily accessible Quinaphos-type ligands, which belong to the most active and selective category of ligands for Rh-catalysed hydrogenation known to date. [source]