A qualitative human-centric evaluation of flexibility in middleware implementations

Today middleware is much more powerful, more reliable and faster than it used to be. Nevertheless, for the application developer, the complexity of using middleware platforms has increased accordingly. The volume and variety of application contexts that current middleware technologies have to support require that developers be able to anticipate the widest possible range of execution environments, desired and undesired effects of different programming strategies, handling procedures for runtime errors, and so on. This paper shows how a generic framework designed to evaluate the usability of notations (the Cognitive Dimensions of Notations Framework, or CDN) has been instantiated and used to analyze the cognitive challenges involved in adapting middleware platforms. This human-centric perspective allowed us to achieve novel results compared to existing middleware evaluation research, typically centered around system performance metrics. The focus of our study is on the process of adapting middleware implementations, rather than in the end product of this activity. Our main contributions are twofold. First, we describe a qualitative CDN-based method to analyze the cognitive effort made by programmers while adapting middleware implementations. And second, we show how two platforms designed for flexibility have been compared, suggesting that certain programming language design features might be particularly helpful for developers.     

The Multifunctional Sactipeptide Ruminococcin C1 Displays Potent Antibacterial Activity In Vivo as Well as Other Beneficial Properties for Human Health

The world is on the verge of a major antibiotic crisis as the emergence of resistant bacteria is increasing, and very few novel molecules have been discovered since the 1960s. In this context, scientists have been exploring alternatives to conventional antibiotics, such as ribosomally synthesized and post-translationally modified peptides (RiPPs). Interestingly, the highly potent in vitro antibacterial activity and safety of ruminococcin C1, a recently discovered RiPP belonging to the sactipeptide subclass, has been demonstrated. The present results show that ruminococcin C1 is efficient at curing infection and at protecting challenged mice from Clostridium perfringens with a lower dose than the conventional antibiotic vancomycin. Moreover, antimicrobial peptide (AMP) is also effective against this pathogen in the complex microbial community of the gut environment, with a selective impact on a few bacterial genera, while maintaining a global homeostasis of the microbiome. In addition, ruminococcin C1 exhibits other biological activities that could be beneficial for human health, as well as other fields of applications. Overall, this study, by using an in vivo infection approach, confirms the antimicrobial clinical potential and highlights the multiple functional properties of ruminococcin C1, thus extending its therapeutic interest.     

A semiotic engineering approach to user interface design

Designing software involves good perception, good reasoning, and a talent to express oneself effectively through programming and interactive languages. Semiotic theories can help HCI designers increase their power to perceive, reason and communicate. By presenting some of the results we have reached with semiotic engineering over the last few years, we suggest that the main contributions of semiotic theory in supporting HCI design are: to provide designers with new perceptions on the process and product of HCI design; to bind together all the stages of software development and use, giving them a unique homogeneous treatment; and to pose innovative questions that extend the frontiers of HCI investigations.     

Mining the impact of evolution categories on object-oriented metrics

Despite the relevance of the software evolution phase, there are few characterization studies on recurrent evolution growth patterns and on their impact on software properties, such as coupling and cohesion. In this paper, we report a study designed to investigate whether the software evolution categories proposed by Lanza can be used to explain not only the growth of a system in terms of lines of code (LOC), but also in terms of metrics from the Chidamber and Kemerer (CK) object-oriented metrics suite. Our results show that high levels of recall (ranging on average from 52 to 72 %) are achieved when using LOC to predict the evolution of coupling and size. For cohesion, we have achieved smaller recall rates (<27 % on average).     

Chromophore‐Linked Substrate (CLS405): Probing Metallo‐β‐Lactamase Activity and Inhibition

Serine‐ and metallo‐β‐lactamases present a threat to the clinical use of nearly all β‐lactam antibiotics, including penicillins, cephalosporins, and carbapenems. Efforts to develop metallo‐β‐lactamase (MBL) inhibitors require suitable screening platforms to allow the rapid determination of β‐lactamase activity and efficient inhibition. Unfortunately, the platforms currently available are not ideal for this purpose. Further progress in MBL inhibitor identification requires inexpensive and widely applicable assays. Herein the identification of an inexpensive and stable chromogenic substrate suitable for use in assays of clinically relevant MBLs is described. (6R,7R)‐3‐((4‐Nitrophenoxy)methyl)‐8‐oxo‐7‐(2‐phenylacetamido)‐5‐thia‐1‐azabicyclo[4.2.0]oct‐2‐ene‐2‐carboxylic acid 5,5‐dioxide (CLS405) was synthesised in a three‐step protocol. CLS405 was then characterised spectroscopically, and its stability and kinetic properties evaluated. With a Δλ_max value of 100 nm between the parent and hydrolysis product, a higher analytical accuracy is possible with CLS405 than with commonly used chromogenic substrates. The use of CLS405 in assays was validated by MBL activity measurements and inhibitor screening that resulted in the identification of N‐hydroxythiazoles as new inhibitor scaffolds for MBLs. Further evaluation of the identified N‐hydroxythiazoles against a panel of clinically relevant MBLs showed that they possess inhibitory activities in the mid‐ to low‐micromolar range. The findings of this study provide both a useful tool compound for further inhibitor identification, and novel scaffolds for the design of improved MBL inhibitors with potential as antibiotics against resistant strains of bacteria.     

Isothermal Microcalorimetry to Investigate Non Specific Interactions in Biophysical Chemistry

Isothermal titration microcalorimetry (ITC) is mostly used to investigate the thermodynamics of “specific” host-guest interactions in biology as well as in supramolecular chemistry. The aim of this review is to demonstrate that ITC can also provide useful information about non-specific interactions, like electrostatic or hydrophobic interactions. More attention will be given in the use of ITC to investigate polyelectrolyte-polyelectrolyte (in particular DNA-polycation), polyelectrolyte-protein as well as protein-lipid interactions. We will emphasize that in most cases these “non specific” interactions, as their definition will indicate, are favoured or even driven by an increase in the entropy of the system. The origin of this entropy increase will be discussed for some particular systems. We will also show that in many cases entropy-enthalpy compensation phenomena occur.     

Rapid detection of pork meat freshness by using L-cysteine-modified gold electrode

In this research, a simple and rapid glucose sensor was developed and applied in the detection of meat glucose. The gold electrode was modified using L-cysteine and nanogold solution, and a polyglutamate–glucose oxidase (GOx) complex was prepared and dropped on the modified electrode; the electrostatic binding between the L-cysteine on the electrode surface and the polyglutamate moiety of the complex resulted in the formation of a GOx-attached electrode. Glucose in meat was detected, and the enzyme electrode showed a quick response. The optimum operating conditions for this sensor were determined as follows: 0.1 M citrate buffer pH 5.0 was found to be suitable for this experiment, and the temperature was kept between 25 and 30 °C which is the suitable range for the GOx activity. A linear relationship was found between 0.1 and 0.9 mM/mL. High pressure liquid chromatography (HPLC) was also used to detect pork meat glucose, and total volatile basic nitrogen (TVBN) production was as well detected as a quality index of pork meat freshness. The results showed that the developed sensor was fast and reliable method for the detection of glucose in meat.     

Comparison of calibration curve fitting methods in the determination of H2S mass fractions in natural gas by GC-SCD

This paper discusses metrologically the best practice regarding the calibration curves applied to H₂S mass fractions determination in natural gas by gas chromatography with sulfur chemiluminescence detection (GC-SCD). Three calibration curves were constructed by performing GC-SCD analysis of different H₂S gas standard concentrations (from 3 mg kg^?1 up to 500 mg kg^?1). These experimental curves are better fitted by an unweighted quadratic calibration curve considering ANOVA approach compared to ASTM D5504-12. Despite this, the obtained results show that these two different calibration curve approaches (ASTM and ANOVA) lead to comparable results. Hence, there are no significant statistical differences between these two approaches based on the hypothesis test applied. However, the quadratic calibration curve presents measurement uncertainties of H₂S mass fractions much lower than the ASTM approach.     

Variability and molecular typing of Streptococcus thermophilus strains displaying different proteolytic and acidifying properties

Proteolytic and acidifying properties of Streptococcus thermophilus strains isolated from yoghurt or cheeses were evaluated. Among 30 strains tested, 12 exhibited cell envelope-associated proteinase activity (PrtS⁺), three displayed a slight PrtS activity (PrtS^+/?) and 15 were PrtS^?, despite the presence of the corresponding gene (prtS) in eight of them. Sequencing of the prtS gene in four PrtS^? and one PrtS⁺ strains revealed that the absence of PrtS activity in the PrtS^? strain probably results from an alteration of the prtS regulation. The strains displaying the highest acidifying capacities were all PrtS⁺. All but one PrtS⁺ strains were phylogenetically close, as shown by the sequencing of their rDNA internal transcribed spacer (ITS) 16S-23S. More specifically, the high proteolytic and acidifying capacities are associated with the presence of a type II-ITS.     

Field-effect transistor with diphthalocyanine thin film

A field effect transistor has been fabricated with organic semiconductors: scandium diphthalocyanine and nickel phthalocyanine. The electrical characteristics are studied in air atmosphere. The influence of the diphthalocyanine film thickness has been detected