Quantitative Techniques (quantitative + techniques)

Distribution by Scientific Domains

Selected Abstracts

Diagnostic and Prognostic Value of Myocardial Perfusion Imaging in Patients with Known or Suspected Stable Coronary Artery Disease

Aman M. Amanullah M.D., Ph.D.
Coronary artery disease is the leading cause of complications and death in the United States and other Western countries, and stress myocardial perfusion study is an important component of the clinical evaluation, stratification, and management. This imaging technique is a well-established modality and has been widely used for the past three decades. New quantitative techniques for the assessment of ventricular function using quantitative gated single-photon emission computed tomography in addition to myocardial perfusion will potentially enhance the role of nuclear cardiology in the management of these patients. This review summarizes the current knowledge of the diagnostic and prognostic uses of stress myocardial perfusion imaging using exercise and pharmacological stress in patients with stable coronary artery disease. [source]

Mucopolysaccharidosis type IIID: 12 new patients and 15 novel mutations,

HUMAN MUTATION, Issue 5 2010
Marlies J. Valstar
Abstract Mucopolysaccharidosis III D (Sanfilippo disease type D, MPS IIID) is a rare autosomal recessive lysosomal storage disorder previously described in only 20 patients. MPS IIID is caused by a deficiency of N-acetylglucosamine-6-sulphate sulphatase (GNS), one of the enzymes required for the degradation of heparan sulphate. So far only seven mutations in the GNS gene have been reported. The clinical phenotype of 12 new MPS IIID patients from 10 families was studied. Mutation analysis of GNS was performed in 16 patients (14 index cases). Clinical signs and symptoms of the MPS IIID patients appeared to be similar to previously described patients with MPS III. Early development was normal with onset of behavioral problems around the age of 4 years, followed by developmental stagnation, deterioration of verbal communication and subsequent deterioration of motor functions. Sequence analysis of the coding regions of the gene encoding GNS (GNS) resulted in the identification of 15 novel mutations: 3 missense mutations, 1 nonsense mutation, 4 splice site mutations, 3 frame shift mutations, 3 large deletions and 1 in-frame small deletion. They include the first missense mutations and a relatively high proportion of large rearrangements, which warrants the inclusion of quantitative techniques in routine mutation screening of the GNS gene. © 2010 Wiley-Liss, Inc. [source]

The phantom of liberty?: economic growth and the vulnerability of small states

Harvey W. Armstrong
This paper is concerned with the relationship between economic growth in small states and their vulnerability. A critical argument in much of the literature on small states, particularly small island states, is that their growth performance is greatly constrained by their vulnerability to exogenous shocks because of their size. These shocks include economic, political and environmental factors, which together dampen the long-run growth rate of these economies. The paper makes use of a global small state data set and appropriate quantitative techniques to test the relationship between growth and vulnerability using the results of Briguglio's Vulnerability Index. The results highlight some of the conceptual shortcomings in the analytical literature on small states, particularly islands, as well as suggesting that the Vulnerability Index is mis-specified. Copyright © 2002 John Wiley & Sons, Ltd. [source]


Across business disciplines, the importance of database research for theory testing continues to increase. The availability of data also has increased, though methods to analyze and interpret these data lag. This research proposes a method for extracting strong measures from survey databases by a progression from qualitative to quantitative techniques. To test the proposed method, this study uses the Industrial Marketing and Purchasing (IMP) survey database, which includes data from firms in several European countries. The proposed method consists of two phases and seven steps, as illustrated in the context of the firm's incremental innovation generation for buyer,seller relationships. This systematic progression moves from a broad but valid empirical case study to the development of a narrow and reliable measure of incremental innovation generation in the IMP database. The proposed method can use supply chain survey databases for theory development without requiring primary data collection, assuming certain conditions. [source]

Comparing the accuracy and precision of three techniques used for estimating missing landmarks when reconstructing fossil hominin crania

Rudolph Neeser
Abstract Various methodological approaches have been used for reconstructing fossil hominin remains in order to increase sample sizes and to better understand morphological variation. Among these, morphometric quantitative techniques for reconstruction are increasingly common. Here we compare the accuracy of three approaches,mean substitution, thin plate splines, and multiple linear regression,for estimating missing landmarks of damaged fossil specimens. Comparisons are made varying the number of missing landmarks, sample sizes, and the reference species of the population used to perform the estimation. The testing is performed on landmark data from individuals of Homo sapiens, Pan troglodytes and Gorilla gorilla, and nine hominin fossil specimens. Results suggest that when a small, same-species fossil reference sample is available to guide reconstructions, thin plate spline approaches perform best. However, if no such sample is available (or if the species of the damaged individual is uncertain), estimates of missing morphology based on a single individual (or even a small sample) of close taxonomic affinity are less accurate than those based on a large sample of individuals drawn from more distantly related extant populations using a technique (such as a regression method) able to leverage the information (e.g., variation/covariation patterning) contained in this large sample. Thin plate splines also show an unexpectedly large amount of error in estimating landmarks, especially over large areas. Recommendations are made for estimating missing landmarks under various scenarios. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source]

hTERT expression in sporadic renal cell carcinomas

Valérie Paradis
Abstract Human telomerase is a specialized reverse transcriptase that catalyses telomeric repeat addition at the ends of chromosomes. Activation of this enzyme is one of the key steps in cell immortalization and carcinogenesis, and one of its components, hTERT, is considered as the rate-limiting factor. While telomerase activity was found to be prognostically relevant in various cancers, results obtained from renal cell carcinomas (RCC) failed to show any correlation with the usual prognostic factors. The aim of the study was to reassess the role of telomerase and its hTERT component in the biological behaviour of RCC using new quantitative techniques, such as the quantitative evaluation of hTERT mRNA level by a real-time RT-PCR procedure and the mesuring of telomerase activity by an ELISA TRAP assay. Since experimental evidence supports a relationship between cell proliferation or c-myc expression and telomerase, the proliferation index and c-myc mRNA levels were also studied. Forty-one RCC (29 conventional renal cell carcinomas (CRCC), 10 papillary RCC and two urothelial carcinomas) were studied. In 73% of cases, normalized hTERT mRNA expression was significantly higher in the tumour sample than in the normal tissue. Telomerase activity was detected in 63% of RCC, while corresponding normal tissue was always negative. Analysis of correlations showed firstly that both telomerase activity and hTERT mRNA level were lower in the group of CRCC versus non-CRCC (TRAP: 0.3±0.1 versus 0.6±0.2, p<0.05; hTERT/PO mRNA: 5±3 versus 37±8, p<0.001, respectively); secondly, that in the group of CRCC, hTERT mRNA expression level was correlated with the stage of the tumour (p=0.01); and thirdly, that no correlation was observed between c-myc mRNA level and hTERT mRNA level. In conclusion, these results support the involvement of telomerase in RCC and the potential interest of hTERT mRNA quantification. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Growth and Development of a Body of Knowledge: 16 Years of New Product Development Research, 1989,2004,

Albert L. Page
In this study, a content analysis was performed on 815 articles focused on new product development (NPD) published in 10 selected leading marketing, management, NPD, and research and development (R&D) journals from 1989 to 2004. Journals selected were a combination of leading journals in the discipline and publications that included NPD articles. NPD articles were classified by a series of key attributes including methodology employed, domains of knowledge utilized, and broad topics explored. The resulting data were then studied to discern trends over time or common characteristics within domains, methodologies, or journals. The study of NPD has grown since the Journal of Product Innovation Management (JPIM) was launched in 1984. This study shows strong growth in the number of articles on NPD in each category of journal selected. The research in the articles has changed: The early focus on a few selected success factors or a staged development process has evolved and broadened over the 16-year period. More variables and more sophisticated models are being studied in NPD articles. The study found a continuing evolution in research topics and increased sophistication in quantitative techniques over the 16-year period. Overall this review of the NPD literature uncovers encouraging signs of a maturing discipline. However, there are concerns about continuing issues in methodology, insufficient study of service innovation, and continued focus on process characteristics instead of other antecedents of NPD success. The service sector seems to be understudied, even as the reality of a service economy is generally acknowledged. The call in a recent meta-analysis to focus more on market and product characteristics and less on process characteristics has not yet been heeded, even by marketing researchers. [source]