Flow biosensing and sampling in indirect electrochemical detection

Miniaturization in biological analyses has several advantages, such as sample volume reduction and fast response time. The integration of miniaturized biosensors within lab-on-a-chip setups under flow conditions is highly desirable, not only because it simplifies process handling but also because measurements become more robust and operator-independent. In this work, we study the integration of flow amperometric biosensors within a microfluidic platform when analyte concentration is indirectly measured. As a case study, we used a platinum miniaturized glucose biosensor, where glucose is enzymatically converted to [Formula: see text] that is oxidized at the electrode. The experimental results produced are strongly coupled to a theoretical analysis of fluid dynamic conditions affecting the electrochemical response of the sensor. We verified that the choice of the inlet flow rate is a critical parameter in flow biosensors, because it affects both glucose and [Formula: see text] transport, to and from the electrode. We identify optimal flow rate conditions for accurate sensing at high time resolution. A dimensionless theoretical analysis allows the extension of the results to other sensing systems according to fluid dynamic similarity principles. Furthermore, we developed a microfluidic design that connects a sampling unit to the biosensor, in order to decouple the sampling flow rate from that of the actual measurement.     

Broadening the horizon: toddlers’ strategies for learning mathematics

The aim of this study is to analyse and discuss those strategies for learning that are essential for toddlers’ development of an understanding of basic aspects of mathematics. Analysis focuses on authentic episodes where toddlers aged one to three are interacting with other people. The settings chosen for the qualitative analysis emanate from a variation theory of learning approach. In such an approach, learning is defined as a change in understanding, and in order to change a person’s understanding of a certain phenomenon, various aspects must be focused on simultaneously. Accordingly, critical aspects that a learner has not been previously able to focus on may emerge during interaction with others since such settings provide an opportunity for the problemisation of differing aspects and perspectives. This study seeks to discern toddlers’ strategies for learning through the observation of those strategies that the toddlers themselves initiate, which may reveal the competence for learning that young children possess.     

ATR-FTIR imaging of albumen photographic prints

The preservation of early 20th century, late 19th century albumen prints is of great concern to collection managers and conservators of photographic materials. Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopic imaging is presented for the first time as analytical methodology for the study of albumen photographs. This paper shows the feasibility of obtaining FTIR images of samples from albumen photographs with a high spatial resolution using a Ge ATR objective coupled with an infrared microscope. The improved spatial resolution compared to FTIR images obtained by the reflection method is due to the high refractive index of the ATR crystal, which gives a high numerical aperture and hence, a higher spatial resolution. The technique reveals detailed information on the organic functional group distribution in the individual layers of embedded cross sections and is used complementary to visual microscopy and scanning electron microscopy/energy dispersed X-ray spectroscopy. The main results of the study are discussed with regard to their historical and artistic significance, and they are compared with data from historical and conservation literature.     

Nonuniform Fuchsian codes for noisy channels

We develop a new transmission scheme for additive white Gaussian noisy (AWGN) channels based on Fuchsian groups from rational quaternion algebras. The structure of the proposed Fuchsian codes is nonlinear and nonuniform, hence conventional decoding methods based on linearity and symmetry do not apply. Previously, only brute force decoding methods with complexity that is linear in the code size exist for general nonuniform codes. However, the properly discontinuous character of the action of the Fuchsian groups on the complex upper half-plane translates into decoding complexity that is logarithmic in the code size via a recently introduced point reduction algorithm.     

Critical review and meta-analysis of spurious hemolysis in blood samples collected from intravenous catheters

Background:

A number of preanalytical activities strongly influence sample quality, especially those related to sample collection. Since blood drawing through intravenous catheters is reported as a potential source of erythrocyte injury, we performed a critical review and meta-analysis about the risk of catheter-related hemolysis.

Materials and methods:

We performed a systematic search on PubMed, Web of Science and Scopus to estimate the risk of spurious hemolysis in blood samples collected from intravenous catheters. A meta-analysis with calculation of Odds ratio (OR) and Relative risk (RR) along with 95% Confidence interval (95% CI) was carried out using random effect mode.

Results:

Fifteen articles including 17 studies were finally selected. The total number of patients was 14,796 in 13 studies assessing catheter and evacuated tubes versus straight needle and evacuated tubes, and 1251 in 4 studies assessing catheter and evacuated tubes versus catheter and manual aspiration. A significant risk of hemolysis was found in studies assessing catheter and evacuated tubes versus straight needle and evacuated tubes (random effect OR 3.4; 95% CI = 2.9–3.9 and random effect RR 1.07; 95% CI = 1.06–1.08), as well as in studies assessing catheter and evacuated tubes versus catheter and manual aspiration of blood (OR 3.7; 95% CI = 2.7–5.1 and RR 1.32; 95% CI = 1.24–1.40).

Conclusions:

Sample collection through intravenous catheters is associated with significant higher risk of spurious hemolysis as compared with standard blood drawn by straight needle, and this risk is further amplified when intravenous catheter are associated with primary evacuated blood tubes as compared with manual aspiration.     

Glycogen phosphorylase isoenzyme BB in the diagnosis of acute myocardial infarction: a meta-analysis

Background

Early diagnosis is crucial for management of patients with suspected acute myocardial infarction (AMI). Among innovative and promising biomarkers, the recent interest raised on glycogen phosphorylase isoenzyme BB (GPBB) has prompted us to perform a meta-analysis of published studies.

Materials and methods:

A systematic electronic search was carried out on PubMed, Web of Science and Google Scholar, with no date restriction, to retrieve all articles that have investigated the early diagnostic performance of GPBB in patients with suspected AMI, and directly reported or allowed calculation of sensitivity and specificity. A meta-analysis of the reported sensitivity and specificity of each study and pooled area under the curve (AUC) was then performed by random effect approach. Heterogeneity was assessed by I-square statistics.

Results:

Eight studies were finally selected for analysis (941 subjects; 506 cases and 435 controls), with a high heterogeneity (I-squared, 86.3%). The resulting pooled estimates and 95% confidence interval were 0.854 (0.801–0.891) for sensitivity, 0.767 (0.713–0.815) for specificity, 0.826 (0.774–0.870) for negative predictive value, 0.802 (0.754–0.844) for positive predictive value, and 0.754 (0.602–0.907) for AUC. In those studies that have simultaneously assessed GPBB and a troponin immunoassay, the combination of these biomarkers did not significantly improve the performance of troponin alone.

Conclusion:

GPBB does not meet the current requirements for an efficient diagnosis of AMI when used as a stand-alone test, whereas its combination with troponin merits further investigation in larger trials.     

Gender differences in the Australian undergraduate STEM student experience: a systematic review

ABSTRACT

In Australia, the number of female graduates in some science, technology, engineering, and mathematics (STEM) disciplines is as low as 15%. Previous reviews exploring the issues affecting female undergraduate STEM students are primarily based in North America and there is yet to be an Australian focused review. This review identifies the factors contributing to the gendered experience of Australian undergraduate STEM students. A systematic review was conducted in November – December 2018 using ERIC, PsycInfo, ProQuest and Scopus databases. From this review, 36 papers that focus on gender differences and university STEM students in Australia were identified. The Australian research suggests the most prominent issue for female STEM students is their lower self-efficacy. Gendered preferences for learning, gendered motivations to pursue STEM degrees, the masculine culture of these fields and gender differences in science identity were also themes identified through the review. This review indicates some gaps in the Australian literature, namely that identity, and other emotional factors, are understudied in the Australian context and an avenue for future research. The findings suggest that science educators should be aware of the gendered experiences of their students to ensure female persistence in university STEM degrees.     

Pattern discernment and pseudo-conceptual development in early childhood mathematics education

In this empirical study, we investigate an early childhood education activity in mathematics on the concept of ‘pattern’. The children participating in the study attend an intermediate form of schooling in Sweden called ‘the preschool class for six-year-olds’, intended to facilitate their transition from preschool to school. Following a prolonged activity over 45 minutes, we analyse for what the children are supported in discerning and what they give as evidence of having discerned in and about patterns. The theoretical point of departure is variation theory, conceptualising learning as increased discernment. The results show that in terms of the important Vygotskian distinction between ‘pseudo concepts’ and ‘concepts (proper)’, the children's discernment and what they are supported in discerning are of the former kind. Pseudo concepts are discussed as integral to the institutional form of the preschool class and premised to be important to the child's further conceptual development.     

Teachers' beliefs and integration of information and communications technology in Italian schools

Abstract

The goal of the present study was to examine teaching styles with information and communications technology (ICT); in Italian schools and in particular to explore whether there is a relationship between personal theories of teaching and learning, levels of competence in ICT, and how ICT is integrated into classroom activities. Teachers with high and low levels of competence in ICT were interviewed in order to examine their beliefs, perceptions, and experiences related to teaching with and without the computer. They were asked to reflect both on themselves as teachers and on their pupils. The results of this preliminary study appeared to indicate that both personal theories of teaching and the level of competence with ICT play a major role in how teachers implement ICT and in their perception of their own and their pupils' motivation