Glucose clamp technique: a method for quantifying insulin secretion and resistance

Methods for the quantification of beta-cell sensitivity to glucose (hyperglycemic clamp technique) and of tissue sensitivity to insulin (euglycemic insulin clamp technique) are described. Hyperglycemic clamp technique. The plasma glucose concentration is acutely raised to 125 mg/dl above basal levels by a priming infusion of glucose. The desired hyperglycemic plateau is subsequently maintained by adjustment of a variable glucose infusion, based on the negative feedback principle. Because the plasma glucose concentration is held constant, the glucose infusion rate is an index of glucose metabolism. Under these conditions of constant hyperglycemia, the plasma insulin response is biphasic with an early burst of insulin release during the first 6 min followed by a gradually progressive increase in plasma insulin concentration. Euglycemic insulin clamp technique. The plasma insulin concentration is acutely raised and maintained at approximately 100 muU/ml by a prime-continuous infusion of insulin. The plasma glucose concentration is held constant at basal levels by a variable glucose infusion using the negative feedback principle. Under these steady-state conditions of euglycemia, the glucose infusion rate equals glucose uptake by all the tissues in the body and is therefore a measure of tissue sensitivity to exogenous insulin.

Comparison of PubMed, Scopus, Web of Science, and Google Scholar: strengths and weaknesses

The evolution of the electronic age has led to the development of numerous medical databases on the World Wide Web, offering search facilities on a particular subject and the ability to perform citation analysis. We compared the content coverage and practical utility of PubMed, Scopus, Web of Science, and Google Scholar. The official Web pages of the databases were used to extract information on the range of journals covered, search facilities and restrictions, and update frequency. We used the example of a keyword search to evaluate the usefulness of these databases in biomedical information retrieval and a specific published article to evaluate their utility in performing citation analysis. All databases were practical in use and offered numerous search facilities. PubMed and Google Scholar are accessed for free. The keyword search with PubMed offers optimal update frequency and includes online early articles; other databases can rate articles by number of citations, as an index of importance. For citation analysis, Scopus offers about 20% more coverage than Web of Science, whereas Google Scholar offers results of inconsistent accuracy. PubMed remains an optimal tool in biomedical electronic research. Scopus covers a wider journal range, of help both in keyword searching and citation analysis, but it is currently limited to recent articles (published after 1995) compared with Web of Science. Google Scholar, as for the Web in general, can help in the retrieval of even the most obscure information but its use is marred by inadequate, less often updated, citation information.

Toward a universal law of generalization for psychological science

A psychological space is established for any set of stimuli by determining metric distances between the stimuli such that the probability that a response learned to any stimulus will generalize to any other is an invariant monotonic function of the distance between them. To a good approximation, this probability of generalization (i) decays exponentially with this distance, and (ii) does so in accordance with one of two metrics, depending on the relation between the dimensions along which the stimuli vary. These empirical regularities are mathematically derivable from universal principles of natural kinds and probabilistic geometry that may, through evolutionary internalization, tend to govern the behaviors of all sentient organisms.

An introduction to implementation science for the non-specialist

BACKGROUND

The movement of evidence-based practices (EBPs) into routine clinical usage is not spontaneous, but requires focused efforts. The field of implementation science has developed to facilitate the spread of EBPs, including both psychosocial and medical interventions for mental and physical health concerns.

DISCUSSION

The authors aim to introduce implementation science principles to non-specialist investigators, administrators, and policymakers seeking to become familiar with this emerging field. This introduction is based on published literature and the authors' experience as researchers in the field, as well as extensive service as implementation science grant reviewers. Implementation science is "the scientific study of methods to promote the systematic uptake of research findings and other EBPs into routine practice, and, hence, to improve the quality and effectiveness of health services." Implementation science is distinct from, but shares characteristics with, both quality improvement and dissemination methods. Implementation studies can be either assess naturalistic variability or measure change in response to planned intervention. Implementation studies typically employ mixed quantitative-qualitative designs, identifying factors that impact uptake across multiple levels, including patient, provider, clinic, facility, organization, and often the broader community and policy environment. Accordingly, implementation science requires a solid grounding in theory and the involvement of trans-disciplinary research teams. The business case for implementation science is clear: As healthcare systems work under increasingly dynamic and resource-constrained conditions, evidence-based strategies are essential in order to ensure that research investments maximize healthcare value and improve public health. Implementation science plays a critical role in supporting these efforts.

The structure of scientific collaboration networks

The structure of scientific collaboration networks is investigated. Two scientists are considered connected if they have authored a paper together and explicit networks of such connections are constructed by using data drawn from a number of databases, including MEDLINE (biomedical research), the Los Alamos e-Print Archive (physics), and NCSTRL (computer science). I show that these collaboration networks form "small worlds," in which randomly chosen pairs of scientists are typically separated by only a short path of intermediate acquaintances. I further give results for mean and distribution of numbers of collaborators of authors, demonstrate the presence of clustering in the networks, and highlight a number of apparent differences in the patterns of collaboration between the fields studied.

The Role of Google Scholar in Evidence Reviews and Its Applicability to Grey Literature Searching

Google Scholar (GS), a commonly used web-based academic search engine, catalogues between 2 and 100 million records of both academic and grey literature (articles not formally published by commercial academic publishers). Google Scholar collates results from across the internet and is free to use. As a result it has received considerable attention as a method for searching for literature, particularly in searches for grey literature, as required by systematic reviews. The reliance on GS as a standalone resource has been greatly debated, however, and its efficacy in grey literature searching has not yet been investigated. Using systematic review case studies from environmental science, we investigated the utility of GS in systematic reviews and in searches for grey literature. Our findings show that GS results contain moderate amounts of grey literature, with the majority found on average at page 80. We also found that, when searched for specifically, the majority of literature identified using Web of Science was also found using GS. However, our findings showed moderate/poor overlap in results when similar search strings were used in Web of Science and GS (10–67%), and that GS missed some important literature in five of six case studies. Furthermore, a general GS search failed to find any grey literature from a case study that involved manual searching of organisations’ websites. If used in systematic reviews for grey literature, we recommend that searches of article titles focus on the first 200 to 300 results. We conclude that whilst Google Scholar can find much grey literature and specific, known studies, it should not be used alone for systematic review searches. Rather, it forms a powerful addition to other traditional search methods. In addition, we advocate the use of tools to transparently document and catalogue GS search results to maintain high levels of transparency and the ability to be updated, critical to systematic reviews.

Molecular imprinting science and technology: a survey of the literature for the years up to and including 2003

Over 1450 references to original papers, reviews and monographs have herein been collected to document the development of molecular imprinting science and technology from the serendipitous discovery of Polyakov in 1931 to recent attempts to implement and understand the principles underlying the technique and its use in a range of application areas. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by papers dealing with fundamental aspects of molecular imprinting and the development of novel polymer formats. Thereafter, literature describing attempts to apply these polymeric materials to a range of application areas is presented.

Meta-analysis: recent developments in quantitative methods for literature reviews

We describe the history and current status of the meta-analytic enterprise. The advantages and historical criticisms of meta-analysis are described, as are the basic steps in a meta-analysis and the role of effect sizes as chief coins of the meta-analytic realm. Advantages of the meta-analytic procedures include seeing the "landscape" of a research domain, keeping statistical significance in perspective, minimizing wasted data, becoming intimate with the data summarized, asking focused research questions, and finding moderator variables. Much of the criticism of meta-analysis has been based on simple misunderstanding of how meta-analyses are actually carried out. Criticisms of meta-analysis that are applicable are equally applicable to traditional, nonquantitative, narrative reviews of the literature. Much of the remainder of the chapter deals with the processes of effect size estimation, the understanding of the heterogeneity of the obtained effect sizes, and the practical and scientific importance of the effect sizes obtained.

Research in clinical reasoning: past history and current trends

BACKGROUND

Research in clinical reasoning has been conducted for over 30 years. Throughout this time there have been a number of identifiable trends in methodology and theory.

PURPOSE

This paper identifies three broad research traditions, ordered chronologically, are: (a) attempts to understand reasoning as a general skill--the "clinical reasoning" process; (b) research based on probes of memory--reasoning related to the amount of knowledge and memory; and (c) research related to different kinds of mental representations--semantic qualifiers, scripts, schemas and exemplars.

RESULTS AND CONCLUSIONS

Several broad themes emerge from this review. First, there is little evidence that reasoning can be characterised in terms of general process variables. Secondly, it is evident that expertise is associated, not with a single basic representation but with multiple coordinated representations in memory, from causal mechanisms to prior examples. Different representations may be utilised in different circumstances, but little is known about the characteristics of a particular situation that led to a change in strategy.

IMPLICATIONS

It becomes evident that expertise lies in the availability of multiple representations of knowledge. Perhaps the most critical aspect of learning is not the acquisition of a particular strategy or skill, nor is it the availability of a particular kind of knowledge. Rather, the critical element may be deliberate practice with multiple examples which, on the hand, facilitates the availability of concepts and conceptual knowledge (i.e. transfer) and, on the other hand, adds to a storehouse of already solved problems.

The emergence of land change science for global environmental change and sustainability

Land change science has emerged as a fundamental component of global environmental change and sustainability research. This interdisciplinary field seeks to understand the dynamics of land cover and land use as a coupled human-environment system to address theory, concepts, models, and applications relevant to environmental and societal problems, including the intersection of the two. The major components and advances in land change are addressed: observation and monitoring; understanding the coupled system-causes, impacts, and consequences; modeling; and synthesis issues. The six articles of the special feature are introduced and situated within these components of study.

Men and things, women and people: a meta-analysis of sex differences in interests

The magnitude and variability of sex differences in vocational interests were examined in the present meta-analysis for Holland's (1959, 1997) categories (Realistic, Investigative, Artistic, Social, Enterprising, and Conventional), Prediger's (1982) Things-People and Data-Ideas dimensions, and the STEM (science, technology, engineering, and mathematics) interest areas. Technical manuals for 47 interest inventories were used, yielding 503,188 respondents. Results showed that men prefer working with things and women prefer working with people, producing a large effect size (d = 0.93) on the Things-People dimension. Men showed stronger Realistic (d = 0.84) and Investigative (d = 0.26) interests, and women showed stronger Artistic (d = -0.35), Social (d = -0.68), and Conventional (d = -0.33) interests. Sex differences favoring men were also found for more specific measures of engineering (d = 1.11), science (d = 0.36), and mathematics (d = 0.34) interests. Average effect sizes varied across interest inventories, ranging from 0.08 to 0.79. The quality of interest inventories, based on professional reputation, was not differentially related to the magnitude of sex differences. Moderators of the effect sizes included interest inventory item development strategy, scoring method, theoretical framework, and sample variables of age and cohort. Application of some item development strategies can substantially reduce sex differences. The present study suggests that interests may play a critical role in gendered occupational choices and gender disparity in the STEM fields.

Sex differences in mental test scores, variability, and numbers of high-scoring individuals

Sex differences in central tendency, variability, and numbers of high scores on mental tests have been extensively studied. Research has not always seemed to yield consistent results, partly because most studies have not used representative samples of national populations. An analysis of mental test scores from six studies that used national probability samples provided evidence that although average sex differences have been generally small and stable over time, the test scores of males consistently have larger variance. Except in tests of reading comprehension, perceptual speed, and associative memory, males typically outnumber females substantially among high-scoring individuals.

Perceptions as hypotheses

Perceptions may be compared with hypotheses in science. The methods of acquiring scientific knowledge provide a working paradigm for investigating processes of perception. Much as the information channels of instruments, such as radio telescopes, transmit signals which are processed according to various assumptions to give useful data, so neural signals are processed to give data for perception. To understand perception, the signal codes and the stored knowledge or assumptions used for deriving perceptual hypotheses must be discovered. Systematic perceptual errors are important clues for appreciating signal channel limitations, and for discovering hypothesis-generating procedures. Although this distinction between 'physiological' and 'cognitive' aspects of perception may be logically clear, it is in practice surprisingly difficult to establish which are responsible even for clearly established phenomena such as the classical distortion illusions. Experimental results are presented, aimed at distinguishing between and disconvering what happens when there is mismatch with the neural signal channel, and when neural signals are processed inappropriately for the current situation. This leads us to make some distinctions between perceptual and scientific hypotheses, which raise in a new form the problem: What are 'objects'?

The Diversity-Innovation Paradox in Science

Prior work finds a diversity paradox: Diversity breeds innovation, yet underrepresented groups that diversify organizations have less successful careers within them. Does the diversity paradox hold for scientists as well? We study this by utilizing a near-complete population of ∼1.2 million US doctoral recipients from 1977 to 2015 and following their careers into publishing and faculty positions. We use text analysis and machine learning to answer a series of questions: How do we detect scientific innovations? Are underrepresented groups more likely to generate scientific innovations? And are the innovations of underrepresented groups adopted and rewarded? Our analyses show that underrepresented groups produce higher rates of scientific novelty. However, their novel contributions are devalued and discounted: For example, novel contributions by gender and racial minorities are taken up by other scholars at lower rates than novel contributions by gender and racial majorities, and equally impactful contributions of gender and racial minorities are less likely to result in successful scientific careers than for majority groups. These results suggest there may be unwarranted reproduction of stratification in academic careers that discounts diversity's role in innovation and partly explains the underrepresentation of some groups in academia.

Nanocatalysis: mature science revisited or something really new?

"Nanomania" has reached the area of heterogeneous catalysis. Nanosized catalyst constituents are important for functions that require structural control over several scales of dimension. Nanocatalysis may be understood as a redefinition of catalyst synthesis: multidimensional structural control is exerted by considering catalysts as inorganic polymers rather than as close-packed crystals. Primary, secondary, and tertiary structural hierarchies translate into molecular building blocks and linkers, the defect structure of crystals, and particle morphology. High-throughput techniques and in situ synthetic analysis are the tools required to arrive at better defined catalytic materials that can fulfil the high expectations created by the incorporation of catalysts into the "nano" research field.

Promoting science-based prevention in communities

In the past decade, prevention science has emerged as a discipline built on the integration of life course development research, community epidemiology, and preventive intervention trials [Am. Psychol. 48 (1993) 1013; Am. J. Community Psychol. 27 (1999) 463; Kellam, S. G., & Rebok, G. W. (1992). Building developmental and etiological theory through epidemiologically based preventive intervention trials. In J. McCord & R. E. Tremblay (Eds.), Preventing antisocial behavior: interventions from birth through adolescence (pp. 162-195). New York: Guilford Press.]. Prevention science is based on the premise that empirically verifiable precursors (risk and protective factors) predict the likelihood of undesired health outcomes including substance abuse and dependence. Prevention science postulates that negative health outcomes like alcohol abuse and dependence can be prevented by reducing or eliminating risk factors and enhancing protective factors in individuals and their environments during the course of development. A growing number of interventions have been found to be effective in preventing adolescent tobacco, alcohol, and other drug abuse, delinquency, violence, and related health risk behaviors by reducing risk and enhancing protection. During the same decade, comprehensive community-based interventions to prevent adolescent health and behavior problems have been widely implemented in the U.S. with federal and foundation support. Despite the advances in the science base for effective preventive interventions and the investments in community-wide preventive interventions, many communities continue to invest in prevention strategies with limited evidence of effectiveness [Am. J. Public Health 84 (1994) 1394; J. Res. Crime Delinq. 39 (2002) 3; J. Community Psychol. 28 (2000) 237; J. Community Psychol. 28 (2000) 237; J. Consult. Clin. Psychol. 67 (1999) 590; Eval. Program Plann. 20 (1997) 367.]. Translating prevention science into community prevention systems has emerged as a priority for prevention research [J. Community Psychol. 28 (2000) 363; J. Appl. Behav. Anal. 28 (1995) 479.]. The Communities That Care (CTC) prevention operating system is a field-tested strategy for activating communities to use prevention science to plan and implement community prevention systems. CTC provides tools that assist communities to use local data on risk and protective factors to identify elevated risks and depressed protective factors in geographic areas where levels of risk are high and levels of protection are low and then to implement tested, effective preventive interventions that reduce the identified risks and enhance protection in these [Developmental Research and Programs. (1997). Communities That Care: a comprehensive prevention program. Seattle, WA: Author; Developmental Research and Programs. (2000a). Communities That Care: a comprehensive prevention program. Seattle: Author; Hawkins, J. D., Catalano, R. F., et al. (1992). Communities That Care: action for drug abuse prevention (1st ed.). A joint publication of the Jossey-Bass social and behavioral science series and the Jossey-Bass education series. San Francisco: Jossey-Bass]. The CTC system is widely implemented, and process evaluations of CTC suggest that it can assist communities to develop more effective prevention systems. This paper describes the background and use of the CTC operating system and results of evaluations of implementation of the system.

Scarless fetal wound healing: a basic science review

SUMMARY

Scar formation is a major medical problem that can have devastating consequences for patients. The adverse physiological and psychological effects of scars are broad, and there are currently no reliable treatments to prevent scarring. In contrast to adult wounds, early gestation fetal skin wounds repair rapidly and in the absence of scar formation. Despite extensive investigation, the exact mechanisms of scarless fetal wound healing remain largely unknown. For some time, it has been known that significant differences exist among the extracellular matrix, inflammatory response, cellular mediators, and gene expression profiles of fetal and postnatal wounds. These differences may have important implications in scarless wound repair.

National differences in gender-science stereotypes predict national sex differences in science and math achievement

About 70% of more than half a million Implicit Association Tests completed by citizens of 34 countries revealed expected implicit stereotypes associating science with males more than with females. We discovered that nation-level implicit stereotypes predicted nation-level sex differences in 8th-grade science and mathematics achievement. Self-reported stereotypes did not provide additional predictive validity of the achievement gap. We suggest that implicit stereotypes and sex differences in science participation and performance are mutually reinforcing, contributing to the persistent gender gap in science engagement.

Parents explain more often to boys than to girls during shared scientific thinking

Young children's everyday scientific thinking often occurs in the context of parent-child interactions. In a study of naturally occurring family conversation, parents were three times more likely to explain science to boys than to girls while using interactive science exhibits in a museum. This difference in explanation occurred despite the fact that parents were equally likely to talk to their male and female children about how to use the exhibits and about the evidence generated by the exhibits. The findings suggest that parents engaged in informal science activities with their children may be unintentionally contributing to a gender gap in children's scientific literacy well before children encounter formal science instruction in grade school.