Is ionic dialysance useful for early detection of vascular access dysfunction? Six illustrative cases

Continuous ionic dialysance monitoring is a useful clinical tool to determine the dialysis dose in real time in each hemodialysis session. We followed up 49 patients for 16 months. Six patients with a Kt reduction of ≥20% in >3 consecutive hemodialysis sessions were identified. Fistulography demonstrated significant stenosis in all 6 patients. Angioplasty was performed in 5 with an excellent angiographic result and optimal Kt levels were restored. Unexplained and persistent Kt reduction in patients with stable chronic kidney disease under hemodialysis could represent, together with an accurate vascular access examination, a practical and additional indirect method for the early detection of vascular access dysfunction.     

Which is better,off-line or real-time scheduling?

Existing results on scheduling indicates that off-line methods are better than real-time methods. This paper gives examples to show that the assertion is not true under fairly general conditions. As a by-product, the paper also shows the potential danger of the existing practice which uses the mean values of random variables as input values to deterministic scheduling methods.     

Science studies and natural sciences: Which is primary,distribution or interdependence between variables?

It is shown that in natural sciences, interdependences between variables are determined regardless of the distributions of variable values, whereas in science studies, distributions should be used as a starting point. This difference is due the nature of measuring instruments: in natural sciences, measurements are performed with the use of devices, while science of science uses human devices adapting themselves to the measured objects. Practical inferences are drawn.     

Coronavirus mapping in scientific publications: When science advances rapidly and collectively,is access to this knowledge open to society?

Scientometrics - The COVID-19 pandemic is creating a global health emergency. Mapping this health emergency in scientific publications demands multiple approaches to obtain a picture as complete as...     

An analysis of dimensionality using factor analysis (true-score theory) and Rasch measurement: what is the difference? Which method is better?

One often hears the question asked, "For questionnaire data measuring a variable, what difference does it make to use factor analysis/principal components analysis (true-score theory) or Rasch measurement in testing for dimensionality?" This paper reports both factor analysis and Rasch measurement analysis for two sets of data. One set of data measures social anxiety for primary school students (N=436, I=10) and the second measures attitude to mathematics for primary-aged students (N=774, I=10). For both sets of data, the factor analysis suggests that the scores are reliable, and that inferences can be made that are valid for measuring school anxiety and attitude to mathematics. For both sets of data analyzed with Rasch measurement techniques, the reliability of the measures, the dimensionality of the measures, and the initial conceptualisation of the items, are called into question. It suggests that one cannot make valid inferences from the measures that were initially set up for true-score theory. The Rasch analysis suggests that items intended to measure a variable should be initially developed on a conceptualized scale from easy to hard, and that students should answer the items from this perspective, so that the Rasch analysis of the data tests this conceptualisation, and a linear scale can be created based on a mathematical measurement model with consistent units (logits).     

Do journals flipping to gold open access show an OA citation or publication advantage?

The effects of Open Access (OA) upon journal performance are investigated. The key research question holds: How does the citation impact and publication output of journals switching (“flipping”) from non-OA to Gold-OA develop after their switch to Gold-OA? A review is given of the literature, with an emphasis on studies dealing with flipping journals. Two study sets with 119 and 100 flipping journals, derived from two different OA data sources (DOAJ and OAD), are compared with two control groups, one based on a standard bibliometric criterion, and a second controlling for a journal’s national orientation. Comparing post-switch indicators with pre-switch ones in paired T-tests, evidence was obtained of an OA Citation advantage but not of an OA Publication Advantage. Shifts in the affiliation countries of publishing and citing authors are characterized in terms of countries’ income class and geographical world region. Suggestions are made for qualitative follow-up studies to obtain more insight into OA flipping or reverse-flipping.

     

Which of three voltammetric methods, when applied to a reversible electrode reaction, can best cope with double-layer capacitance and severe uncompensated resistance?

The presence of uncompensated resistance and double-layer capacitance confounds the accurate measurements of the bulk concentration of electroreactant and the reversible half-wave potential from an experimental voltammogram. It is pertinent to ask which simple voltammetric technique-chronopotentiometry, linear-scan voltammetry, or potential-step voltammetry-is best able to confront these difficulties. We have carried out a modeling study in an attempt to answer this question. First, we devised an exact method of simulating each variety of reversible voltammogram, incorporating the effects of resistance and capacitance. Next, we developed an unprejudiced method of analyzing these voltammograms to recover both electrochemical parameters. Then we performed a sensitivity analysis on a very large number of simulated voltammograms by measuring the apparent half-wave potential and concentration when slightly erroneous values of resistance and capacitance were employed in the recovery step. Thereby we hoped to ascertain how uncertainty in the magnitudes of the two interfering electrical elements affects the measured values of the two electrochemical parameters. Basing conclusions on the sizes of the four sensitivity indices, we conclude, surprisingly, that linear-scan voltammetry, not chronopotentiometry, is most often the method of choice.     

Peer review versus bibliometrics: Which method better predicts the scholarly impact of publications?

Scientometrics - In this work, we try to answer the question of which method, peer review versus bibliometrics, better predicts the future overall scholarly impact of scientific publications. We...     

Turbulent boundary layers: is the wall falling or merely wobbling?

A quick passage through five centuries of turbulence research highlights the major milestones. The more recent cornerstones include Kolmogorov??s equilibrium theory of turbulence spectrum, the universal logarithmic law of wall-bounded flows, and the proliferation of direct numerical simulations. Evidence of recent fault lines in all three major achievements is presented, but also novel remedies as well as a few contemporary accomplishments are pointed out.     

Contract duration: Barrier or bridge to successful public-private partnerships?

Public-private partnerships (PPPs) are predominantly executed through the use of formal contracts which define the relationship between a public agency and private supplier. As such, a PPP is not a generic contract between buyer and supplier but rather a specific contractual arrangement between a public buyer and private supplier. The contract captures the responsibilities of each party in achieving a specific set of performance objectives. Given budgetary pressures faced by public agencies, there is an increasing need for suppliers to make investments which could reduce future-year costs of meeting contract performance objectives. This research addresses two overarching questions specific to the issue of private, supplier-side investment. First, “how does public agency and private supplier perception of risk influence contract duration?” and second, “how does contract duration influence private investment?” To answer these questions, structured interviews were conducted with those in public agencies and private, supplier firms actively engaged in PPPs. Factors suspected to contribute to the risk position of public and private actors were evaluated. Additionally, linkages between public buyer-private supplier risk position, contract duration and private, supplier-side investment were addressed. Outcomes suggest properly structured long-term contracts may: 1) provide the risk mitigation mechanisms needed for both public and private actors, and 2) facilitate private, supplier-side investment.     

Impact factor: outdated artefact or stepping-stone to journal certification?

A review of Garfield??s journal impact factor and its specific implementation as the Thomson Reuters impact factor reveals several weaknesses in this commonly-used indicator of journal standing. Key limitations include the mismatch between citing and cited documents, the deceptive display of three decimals that belies the real precision, and the absence of confidence intervals. These are minor issues that are easily amended and should be corrected, but more substantive improvements are needed. There are indications that the scientific community seeks and needs better certification of journal procedures to improve the quality of published science. Comprehensive certification of editorial and review procedures could help ensure adequate procedures to detect duplicate and fraudulent submissions.     

Engineering Education Research: Discipline,Community, or Field?

Engineering education research has experienced a notable scale‐up in recent years through the development of departments and degree programs, high‐profile publication outlets, research agendas, and meetings. We begin by reviewing these developments, contextualizing them historically, and clarifying some relevant terminology. We then use observational data collected at the 2007 inaugural International Conference on Research in Engineering Education (ICREE) to examine how engineering education is variously conceptualized as a discipline, community of practice, and/or field. We also examine how ICREE participants engaged with questions about the infrastructure and major goals of engineering education research. Our data reveals both an overall lack of clarity and continued sense of ambiguity about the identity and status of engineering education research. We conclude by recommending that participants and stakeholders work to clarify the goals and objectives of engineering education research, especially to inform the continued development of the field's identity and supporting infrastructures.     

Process models: plans,predictions, proclamations or prophecies?

Design process models have a complex and changing relationship to the processes they model, and mean different things to different people in different situations. Participants in design processes need to understand each other’s perspectives and agree on what the models mean. The paper draws on philosophy of science to argue that understanding a design process model can be seen as an imagination game governed by agreed rules, to envisage what would be true about the world if the model were correct. The rules depend on the syntax and content of the model, on the task the model is used for, and on what the users see the model as being. The paper outlines twelve alternative conceptualizations of design process models—frames, pathways, positions, proclamations, projections, predictions, propositions, prophecies, requests, demands, proposals, promises—and discusses when they fit situations that stakeholders in design processes can be in. Articulating how process models are conceptualised can both help to understand how process management works and help to resolve communication problems in industrial practice.