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PubMed2006

Measurement and meaningfulness in conservation science.

Incomplete databases often require conservation scientists to estimate data either through expert judgment or other scoring, rating, and ranking procedures. At the same time, ecosystem complexity has led to the use of increasingly sophisticated algorithms and mathematical models to aid in conservation theorizing, planning, and decision making. Understanding the limitations imposed by the scales of measurement of conservation data is important for the development of sound conservation theory and policy. In particular, biodiversity valuation methods, systematic conservation planning algorithms, geographic information systems (GIS), and other conservation metrics and decision-support tools, when improperly applied to estimated data, may lead to conclusions based on numerical artifact rather than empirical evidence. The representational theory of measurement is described here, and the description includes definitions of the key concepts of scale, scale type, and meaningfulness. Representational measurement is the view that measurement entails the faithful assignment of numbers to empirical entities. These assignments form scales that are organized into a hierarchy of scale types. A statement involving scales is meaningful if its truth value is invariant under changes of scale within scale type. I apply these concepts to three examples of measurement practice in the conservation literature. The results of my analysis suggest that conservation scientists do not always investigate the scale type of estimated data and hence may derive results that are not meaningful. Recognizing the complexity of observation and measurement in conservation biology, and the constraints that measurement theory imposes, the examples are accompanied by suggestions for informal estimation of the scale type of conservation data and for conducting meaningful analysis and synthesis of this information.

Algorithms↗
PubMed2004

[Incidence and the progression of the acute-phase of the retinopathy of prematurity in infants hospitalized in Neonatology Department of University of Medical Sciences in Poznań].

PURPOSE: The assessment of the epidemiological data of acute-phase of retinopathy of prematurity (ROP). MATERIAL AND METHODS: Infants with birth weights less than 1500g and birth dates between April 1, 2002, and May 30, 2003, admitted to special care baby unit in Department of Neonatology in Poznan, were examined. The incidence of retinopathy of prematurity, infants sex, multiple births, the onset of acute-phase ROP (considering the day of life and postmenstrual age) and also the day of life, at which the treatment was started, were analysed. RESULTS: Among 190 infants enrolled to the study 48.9% were female and 51.1% were male. There were 20.5% infants from multiple births. In the examined group in infants with a birth weight under 1250g the incidence of ROP was 32.6% and in infants with a birth weight above 1250g--7.4%. The ROP was diagnosed earliest in 4th week of life, the latest in 12th week of life (mean time of diagnosis the 8th week of life). The earliest time of performing the treatment with diode laser was 37th day of life, the latest--97th day of life (mean time of treatment the 67.5th day of life). CONCLUSIONS: Presented epidemiological data may be helpful in foreseeing the natural history of acute-phase of ROP in population of Polish premature infants with a birth weight under 1500g.

Age of Onset↗
PubMedDate not supplied

Recipients of oocyte donation: an integrative review.

OBJECTIVE: To conduct a systematic review of published research to provide a synthesis of the psychosocial characteristics of donor oocyte recipient women. DATA SOURCES: The sample of published studies was selected from 1983 to September 2002. Retrieval of the studies used online computer searches from CINAHL, MEDLINE, PsycINFO, and Wilson's Social Science Abstracts using the terms reproduction techniques, in vitro fertilization, oocyte donation, oocyte recipients, and egg donation; citations from references and bibliographies of previously located articles; and two 60-minute retrieval sessions with a librarian specializing in health science literature. STUDY SELECTION: The majority of studies retrieved were completed in the natural sciences. The final sample resulted in 16 studies. DATA EXTRACTION: Each study was read and the data were extracted using a survey instrument developed by the investigator. DATA SYNTHESIS: Multiple methodologies were used in the sample; most were exploratory, retrospective, and descriptive studies. Thus, the data were analyzed using a qualitative discursive approach. A total of 827 donor oocyte recipient women participated in the studies. CONCLUSIONS: Published research investigating the psychosocial characteristics of donor recipient women was categorized into six focused areas: motivation; desired donor characteristics; selection of a known versus an anonymous donor; demographic, educational, and psychosocial profiles; disclosure of the method of conception to family members, friends, and the resulting child; and the relationship between the oocyte recipient and her resulting offspring. Research involving the psychosocial aspects of donor oocyte recipient women is in the infancy stage.

Attitude to Health↗
PubMed1989

The science of public health surveillance.

Improved public health surveillance can lead to earlier implementation of prevention and control measures. Better surveillance data lead to a more rational establishment of priorities. More timely and accurate data facilitate earlier epidemic detection and control. With better surveillance data, the impact of intervention activities and other public health programs can be evaluated more accurately. In this paper we describe how to improve the science of surveillance in terms of data collection, analysis, and dissemination and its application to public health practice. We then discuss the potential benefits and costs of such efforts and suggest methods for evaluating alternative approaches. The argument for science in surveillance, on the other hand, may be subject to excess. Surveillance is not an end unto itself, but rather a tool. This tool should be refined and modified to adapt to the goals of a particular public health program. It is the development of methods to apply creative ideas to surveillance, and the rigorous assessment of the process, that will benefit from the application of scientific principles.

Data Interpretation, Statistical↗
PubMed2001

Exploratory visualization software for reporting environmental survey results.

Environmental surveys yield three principal products: maps, a set of data tables, and a textual report. The relationships between these three elements, however, are often cumbersome to present, making full use of all the information in an integrated and systematic sense difficult. The published paper report is only a partial solution. Modern developments in computing, particularly in cartography, GIS, and hypertext, mean that it is increasingly possible to conceive of an easier and more interactive approach to the presentation of such survey results. Here, we present such an approach which links map and tabular datasets arising from a vegetation survey, allowing users ready access to a complex dataset using dynamic mapping techniques. Multimedia datasets equipped with software like this provide an exciting means of quick and easy visual data exploration and comparison. These techniques are gaining popularity across the sciences as scientists and decision-makers are presented with increasing amounts of diverse digital data. We believe that the software environment actively encourages users to make complex interrogations of the survey information, providing a new vehicle for the reader of an environmental survey report.

Conservation of Natural Resources↗
PubMed2002

The development of science achievement in middle and high school. Individual differences and school effects.

Using data from the Longitudinal Study of American Youth (LSAY), hierarchical linear models (HLMs) were used to model the growth of student science achievement in three areas (biology, physical science, and environmental science) during middle and high school. Results showed significant growth in science achievement across all areas. The growth was quadratic across all areas, with rapid growth at the beginning grades of middle school but slow growth at the ending grades of high school. At the student level, socioeconomic status (SES) and age were related to the rate of growth in all areas. There were no gender differences in the rate of growth in any of the three areas. At the school level, variables associated with school context (school mean SES and school size) and variables associated with school climate (principal leadership, academic expectation, and teacher autonomy) were related to the growth in science achievement. Initial (Grade 7) status in science achievement was not associated with the rate of growth in science achievement among either students or schools in any of the three areas.

Adolescent↗
PubMed1992

Unusual structure of the human immunodeficiency virus type 1 trans-activation response element.

The trans-activation response element (TAR) of human immunodeficiency virus type 1 is a structured RNA consisting of the first 60 nucleotides of all human immunodeficiency virus type 1 RNAs. Computer analyses and limited structural analyses indicated that TAR consists of a stem-bulge-loop structure. Mutational analyses showed that sequences in the bulge are required for Tat binding, whereas sequences in both the bulge and the loop are required for trans activation. In this study, we probed the structures of TAR and various mutants of TAR with chemical probes and RNases and used these methods to footprint a Tat peptide on TAR. Our data show that the structure of wild-type TAR is different from previously published models. The bulge, a Tat-binding site, consists of four nucleotides. The loop is structured, rather than simply single stranded, in a fashion reminiscent of the structures of the tetraloop 5'-UUCG-3' and the GNRA loop (C. Cheong, G. Varani, and I. Tinoco, Jr., Nature [London] 346:680-682, 1990; H.A. Heus and A. Pardi, Science 253:191-193, 1991). RNA footprint data indicate that three bases in the bulge are protected and suggest that a conformational change occurs upon Tat binding.

Base Sequence↗
PubMed2003

Traveling front solutions to directed diffusion-limited aggregation, digital search trees, and the Lempel-Ziv data compression algorithm.

We use the traveling front approach to derive exact asymptotic results for the statistics of the number of particles in a class of directed diffusion-limited aggregation models on a Cayley tree. We point out that some aspects of these models are closely connected to two different problems in computer science, namely, the digital search tree problem in data structures and the Lempel-Ziv algorithm for data compression. The statistics of the number of particles studied here is related to the statistics of height in digital search trees which, in turn, is related to the statistics of the length of the longest word formed by the Lempel-Ziv algorithm. Implications of our results to these computer science problems are pointed out.

Journal Article↗
PubMed1996

Determination of the relative neutron sensitivity of a C-CO2 ionization chamber.

The neutron sensitivity of a C-CO2 ionization chamber has been experimentally determined in the neutron energy range of 0.1-1.2 MeV. Eleven kU data were obtained which ranged from 0.04 to 0.1 as a function of neutron energy. There were two peaks in the spectrum of the kU factor, and their positions corresponded to the resonance energies of the kerma factors of carbon dioxide, of which the energies are about 0.4 and 1 MeV. The present data agree with the data obtained at the National Institute for Radiological Sciences in Chiba, Japan (NIRS). The energy dependences of the sensitivity were calculated by using the kerma and the W-value ratios of gas to soft tissue for comparison. The experimental data were reproduced well by the calculations.

Biophysical Phenomena↗
PubMed1987

The dust distribution within the inner coma of comet P/Halley 1982i: encounter by Giotto's impact detectors.

Analysis of the data from Giotto's Dust Impact Detection System experiment (DIDSY) is presented. These data represent measurement of the size of dust grains incident on the Giotto dust shield along its trajectory through the coma of comet P/Halley on 1986 March 13/14. First detection occurred at some 287000 km distance from the nucleus on the inbound leg; the majority of the DIDSY subsystems remained operational after closest approach (604 km) yielding the last detection at about 202000 km from the nucleus. In order to improve the data coverage (and especially for the smallest grains, to approximately 10(-19) kg particle mass), data from the PIA instrument has been combined with DIDSY data. Flux profiles are presented for the various mass channels showing, to a first approximation, a 1/R2 flux dependence, where R is the distance of the detection point from the cometary nucleus, although significant differences are noted. Deviations from this dependence are observed, particularly close to the nucleus. From the flux profiles, mass and geometrical area distributions for the dust grains are derived for the trajectory through the coma. Groundbased CCD imaging of the dust continuum in the inner coma at the time of encounter is also used to derive the area of grains intercepted by Giotto. The results are consistent with the area functions derived by Giotto data and the low albedo of the grains deduced from infrared emission. For the close encounter period (-5 min to +5 min), the cumulative mass distribution function has been investigated, initially in 20 second periods; there is strong evidence from the data for a steepening of the index of the mass distribution for masses greater than 10(-13) kg during passage through dust jets which is not within the error limits of statistical uncertainty. The fluences for dust grains along the entire trajectory is calculated; it is found that extrapolation of the spectrum determined at intermediate masses (cumulative mass index alpha = 0.85) is not able to account for the spacecraft deceleration as observed by the Giotto Radio Science Experiment and by ESOC tracking operations. Data at large masses (>10(-8) kg) recently analysed from the DIDSY data set show clear evidence of a decrease in the mass distribution index at these masses within the coma, and it is shown that such a value of the mass index can provide sufficient mass for consistency with the observed deceleration. The total particulate mass output from the nucleus of comet P/Halley at the time of encounter would be dependent on the maximum mass emitted if this change in slope observed in the coma were also applicable to the emission from the nucleus; this matter is discussed in the text. The flux time profiles have been converted through a simple approach to modeling of the particle trajectories to yield an indication of nucleus surface activity. There is indication of an enhancement in flux at t approximately -29 s corresponding to crossing of the dawn terminator, but the flux detected prior to crossing of the dawn terminator is shown to be higher than predicted by simple modelling. Further enhancements corresponding to jet activity are detected around +190 s and +270 s.

Astronomical Phenomena↗
PubMed1978

A union catalog of monographs: another approach.

The rationale for and the production of the 1977 TALON Union Catalog of Monographs are described. The 158,859 records include the existing machine-readable records for six health sciences libraries plus the cataloging of six others, converted by matching other data bases and by keypunching. The method and costs of production are discussed. Use of Computer-Output-Microfiche (COM) significantly decreased the cost and time required for publication. The $.076 unit cost per entry, with both author and title access for the COM method, is almost one-half the unit cost for the previous method which offered only main-entry access. The TALON Catalog compares favorably with the Midwest Medical Union Catalog. The addition of the title index significantly increases its usefulness. However, the unique feature of the TALON Catalog may be its machine-readable form which offers the potential for quantitative analyses of health sciences library collections. Such data may be essential for rational management of limited library funds.

Books↗
PubMed2005

An introduction to latent growth models: analysis of repeated measures physical performance data.

The purpose of this paper is to introduce the Latent Growth Model (LGM) to researchers in exercise and sport science. Although the LGM has several merits over traditional analysis techniques in analyzing change and was first introduced almost 20 years ago, it is still underused in exercise and sport science research. This statistical model can be applied to any repeated measures data, but it is most useful when one has an a priori hypothesis about the patterns of change. The strengths of latent growth modeling include: (a) both individual and group levels of change are estimated, (b) either a linear or a curvilinear trajectory can represent individual change, (c) occasions of measurement need not be equally spaced, (d) the statistical model can account for measurement errors, (e) the model can easily include multiple predictors or correlates of change, and (f) as in general structural equation models, statistical models are flexible and allow one to extend the basic idea in several ways, such as comparing changes between groups and examining the change in multivariate latentfactors. In this paper, the basics and an extension of latent growth modeling are explained, and examples with longitudinal physical performance data are presented, along with detailed analysis procedures and considerations.

British Columbia↗
PubMed2004

ECLAMC: the Latin-American collaborative study of congenital malformations.

DEFINITION: ECLAMC ('Estudio Colaborativo Latino Americano de Malformaciones Congenitas') is a program for the clinical and epidemiological investigation of risk factors in the etiology of congenital anomalies in Latin-American hospitals, using a case-control methodological approach. It is a voluntary agreement among professionals lacking institutional base as well as designated budgets. ECLAMC has been usually funded by research-funding agencies rather than public health ministries. The National Research Councils of Argentina and Brazil have been the main sources of support during its 36 years of existence. Since vital and health statistics are unreliable in South America, ECLAMC collects all the information required for the denominators in a hospital-based sample of births. ECLAMC can be defined as a continental network of persons interested in research and prevention of birth defects. HISTORY AND EVOLUTION: From the institutional point of view, ECLAMC has had headquarters in diverse centers of Argentina and Brazil, but always as an independent research project, without a defined administrative link. ECLAMC began operating in 1967, as an investigation limited to the city of Buenos Aires, Argentina, and it gradually expanded until covering all the 10 countries of South America as well as Costa Rica and the Dominican Republic. Even though ECLAMC has maintained essentially the same original experimental design since 1967, due to the data accumulated by the program, the increasing experience as well as the development in science, technical modifications occurred including a DNA bank and a fully informatized data handling system. Since 1974 ECLAMC has been a founder member of the International Clearinghouse for Birth Defects Monitoring Systems; since 1994 a WHO Collaborating Center for the Prevention of Congenital Malformations, and since 2000 a collaborating member of the NIH Global Netwok for Women's and Children's Health Research. METHODOLOGY: The maternity hospital network of ECLAMC examines around 200,000 births per year. All major and minor anomalies diagnosed at birth in infants weighing 500 g or more are registered according to a manual of procedures. The next non-malformed baby of the same sex born in the same hospital is selected as a control subject for each case. Thus, a one-to-one healthy control group matched by sex, time and place of birth is obtained. As a system of epidemic surveillance, ECLAMC systematically observes the fluctuations in the frequencies of different malformations and, in the case of an alarm for a probable epidemic of a given malformation, at a given moment, and given area, it acts to identify its cause. As termination of pregnancy has severe legal restrictions in South America, prevention of birth defects should concentrate on primary, preconceptional and tertiary measures. Tertiary measures aim to avoid complications of the affected patients from the medical, psychological, and social standpoints.

Biomedical Research↗
PubMed2006

Design and implementation of security in a data collection system for epidemiology.

Health informatics can benefit greatly from the e-Science approach, which is characterised by large scale distributed resource sharing and collaboration. Ensuring the privacy and confidentiality of data has always been the first requirement of health informatics systems. The PsyGrid data collection system, addresses both, providing secure distributed data collection for epidemiology. We have used Grid-computing approaches and technologies to address this problem. We describe the architecture and implementation of the security sub-system in detail.

Computer Security↗