AutoRELAX: automatically RELAXing a goal model to address uncertainty

Dynamically adaptive systems (DAS) must cope with system and environmental conditions that may not have been fully understood or anticipated during development. RELAX is a fuzzy logic-based specification language for identifying and assessing sources of environmental uncertainty, thereby making DAS requirements more tolerant of unanticipated conditions. This paper presents AutoRELAX, an approach that automatically generates RELAXed goal models to address environmental uncertainty. Specifically, AutoRELAX identifies goals to RELAX, which RELAX operators to apply, and the shape of the fuzzy logic function that establishes the goal satisfaction criteria. AutoRELAX generates different solutions by making tradeoffs between minimizing the number of RELAXed goals and maximizing delivered functionality by reducing the number of adaptations triggered by minor and adverse environmental conditions. In a recent extension, AutoRELAX uses a stepwise adaptation of weights to balance these two competing concerns and thereby further improve the utility of AutoRELAX. We apply it to two industry-based applications involving network management and a robotic controller, respectively.     

Organizational impact of system quality,information quality,and service quality

Increased organizational dependence on information systems drives management attention towards improving information systems’ quality. A recent survey shows that “Improve IT quality” is one of the top concerns facing IT executives. As IT quality is a multidimensional measure, it is important to determine what aspects of IT quality are critical to organizations to help Chief Information Officers (CIOs) to devise effective IT quality improvement strategies. In this research, we model the relationship between information systems’ (IS) quality and organizational impact. We hypothesize greater organizational impact in situations in which system quality, information quality and service quality are high. We also hypothesize a positive relationship between system quality and information quality. We test our hypotheses using survey data. Our structural equation model exhibits a good fit with the observed data. Our results show that IS service quality is the most influential variable in this model (followed by information quality and system quality), thus highlighting the importance of IS service quality for organizational performance. This paper contributes theoretically to IS success models through the system quality-to-information quality and IS quality-to-organizational impact links. Implications of our results for practice and research are discussed.     

Academic effectiveness of podcasting: A comparative study of integrated versus supplemental use of podcasting in second language classes

With podcasting gaining more mainstream adoption in higher education, it’s critical to examine its effectiveness in improving the student learning experience. To this end, this paper examines the effectiveness of podcasts integrated into the curriculum (PIC) versus podcasts as supplemental material (PSM). Considering recent empirical work on the effectiveness of podcasting, this study collected data from students enrolled in lower level and upper level language courses. Results revealed an inconclusive relationship among PIC students’ learning outcomes (as measured by their final grades). In contrast, however, our findings indicate a strong relationship between the use of PSM and students’ final grades, particularly in upper level courses.     

Lipid and fatty acyl composition of rat brain capillary endothelia isolated by a new technique

A method is described for the isolation of pure capillary endothelia from rat brain and the phospholipid composition of these cells is reported. This method is rapid and requires only a small amount of starting material. It involves: (a) tissue disruption by high speed homogenization, (b) separation of the capillary endothelia from other brain structures using sucrose gradients, and (c) a final purification using a glass bead column. Choline and ethanolamine phosphoglycerides were found to be the predominant lipid classes of these cells amounting to 31.9% and 24.4%, respectively, of total phospholipids. The choline phosphoglycerides consisted almost exclusively of 1,2-diacyl glycerophosphorylcholine, whereas the ethanolamine phosphoglycerides consisted of approximately equal amounts of 1,2-diacyl and 1-alk-l’-enyl-2-acyl glycerophosphorylethanolamine. The composition of the constituent fatty acids of both choline and ethanolamine phosphoglycerides and the alk-1-enyl composition of ethanolamine phosphoglycerides is reported. Saturated fatty acids accounted for 45% of the total fatty acids in choline phosphoglycerides and for 53% in ethanolamine phosphoglycerides. Arachidonic acid accounted for approximately 48% of the total fatty acids in alk-1-enyl ethanolamine phosphoglyceride.     

Thermal,hydrolytic, anticorrosive,and tribological properties of alkyd‐silicone hyperbranched resins with high solid content

Novel alkyd hyperbranched resins (AHBRs) modified with a Z‐6018 silicone (a polysiloxane intermediate) and with high solid content were synthesized by etherification reaction using an acid catalyst. Different molar ratios of AHBR to silicone were used. Structural, thermal, hydrolytic, anticorrosive, and tribological properties were studied using infrared (IR) analysis, nuclear magnetic resonance (NMR), vapor pressure osmometry (VPO), thermogravimetric analysis (TGA), acid value, electrochemical impedance spectroscopy (EIS), and pin‐on‐disk friction. IR and NMR provide evidence of grafting of the silicone on AHBR; the efficiency of grafting was quantified by TGA. Thermal stability was studied also by acid value analysis. Grafting increases the number average molecular mass, enhances thermal stability, and improves significantly hydrolytic stability. Corrosion resistance on steel is improved by two orders of magnitude, hence our modified materials can be used as highly effective anticorrosion coatings. Grafting lowers dynamic friction dramatically, more so at higher concentrations of silicone. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and swelling properties of homopolymeric alginic acid fractions/poly(N‐isopropyl acrylamide) graft copolymers

Graft copolymers of crosslinked poly(N‐isopropyl acrylamide) (PNIPAAm) and homopolyguluronic acid (GG) and homopolymannuronic acid (MM) fractions of alginic acid were synthesized. MM and GG block fractions were obtained by partial acid hydrolysis of the alkaline extract from the brown seaweed Macrocystis pyrifera. The conjugation of these block fractions with the synthetic polymer was achieved by amidation with crosslinked PNIPAAm functionalized with an amino group at the end of the polymer chain. The structure of conjugates was determined by Fourier transform infrared and NMR spectroscopy. Atomic force microscopy of the graft copolymer GG‐g‐PNIPAAm showed a regular porous pattern, whereas the MM‐g‐PNIPAAm graft copolymer showed a regular netlike structure. Aqueous solutions of the synthesized graft copolymers afforded hydrogels by stirring with 0.1M CaCl₂. The hydrogels showed a well‐defined stimulus–response to temperature and pH. The swelling, thermal, and pH characterizations demonstrated the superior properties of the GG‐g‐PNIPAAm hydrogel over the MM‐g‐PNIPAAm hydrogel. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42398.     

Impedance model of electrolyte-insulator-semiconductor structure with porous silicon semiconductor

We present a generic impedance model for the porous silicon|electrolyte structure that is valid for a range of interfacial layers and bias in these structures. The model is validated using three widely different porous structures: short irregular silicon columns and pores, long cylindrical silicon columns and pores; and branched interconnected silicon microchannels and voids in a mesh structure. The model incorporates appropriate RC or constant phase elements for the different parts of the porous structure, namely, the top of the silicon columns (channels)|electrolyte, the column (channel) walls|electrolyte in the pores/channels, and the electrolyte|semiconductor interface at the base of the pores/channels. This physical model underscores the effects of column/channel depletion and accumulation, either due to applied bias or change of surface charge, to the impedance spectra of the device. The model helps to explain why the porosity needs to be optimized for specific applications and helps as a measurement tool for optimization.     

Butyrate and Propionate Restore the Cytokine and House Dust Mite Compromised Barrier Function of Human Bronchial Airway Epithelial Cells

Barrier dysfunction of airway epithelium contributes to the development of allergies, airway hyper-responsiveness and immunological respiratory diseases. Short-chain fatty acids (SCFA) enhance and restore the barrier function of the intestinal epithelium. This study investigated whether acetate, propionate and butyrate enhance the integrity of bronchial epithelial cells. Differentiating human bronchial epithelial cells (16HBE) grown on transwells were exposed to butyrate, propionate and acetate while trans-epithelial electrical resistance was monitored over time. Restorative effects of SCFA were investigated by subsequent incubation of cells with IL-4, IL-13 or house dust mite extract and SCFA. SCFA effects on IL-4-induced cytokine production and the expression of zonula occludens-1 (ZO-1) and Mitogen-activated protein kinases (MAPK) signalling pathways were investigated by ELISA and Western blot assays. Propionate and butyrate enhanced the barrier function of differentiating 16HBE cells and induced complete recovery of the barrier function after exposure to the above-mentioned stimuli. Butyrate decreased IL-4-induced IL-6 production. IL-4 decreased ZO-1 protein expression and induced phosphorylation of extracellular signal-regulated protein kinases 1/2 (ERK1/2) and c-Jun N-terminal kinases (JNK) in 16HBE cells, both of which could be restored by SCFA. SCFA showed prophylactic and restorative effects on airway epithelial barrier function, which might be induced by increased ZO-1 expression.