Theory, explanation, and a third generation of theoretical development in social gerontology

Efforts at cumulative knowledge building in social gerontology have been lax, judging from research articles published in journals between 1990 and 1994. Too little attention has been paid to the cumulative development of theory; readers are left with many empirical generalizations but underdeveloped explanations by which to interpret findings and build upon them in subsequent research. To assist future theory development in social gerontology, we review seven theoretical perspectives referenced most frequently in recent journals: (1) social constructionist, (2) social exchange, (3) life course, (4) feminist, (5) age stratification (age and society), (6) political economy of aging, and (7) critical theory. We suggest that, taken together, these represent a "third generation" of explanation in social gerontology, noting their debt to older and more established traditions in social science theory. We argue that authors and journal reviewers should place more emphasis on theory development - which means, most simply, the construction of explicit explanations in accounting for empirical findings - if knowledge development about social aspects of aging is to be cumulative, systematic, and incremental.     

A Completeness Proof for Bisimulation in the pi-calculus Using Isabelle

We use the interactive theorem prover Isabelle to prove that the algebraic axiomatization of bisimulation equivalence in the pi-calculus is sound and complete. This is the first proof of its kind to be wholly machine checked. Although the result has been known for some time the proof had parts which needed careful attention to detail to become completely formal. It is not that the result was ever in doubt; rather, our contribution lies in the methodology to prove completeness and get absolute certainty that the proof is correct, while at the same time following the intuitive lines of reasoning of the original proof. Completeness of axiomatizations is relevant for many variants of the calculus, so our method has applications beyond this single result. We build on our previous effort of implementing a framework for the pi-calculus in Isabelle using the nominal data type package, and strengthen our claim that this framework is well suited to represent the theory of the pi-calculus, especially in the smooth treatment of bound names.     

Corrosion–microstructure interrelations in new low-lead and lead-free brass alloys

ABSTRACT

Stress-relieving heat treatment has been reported to deplete the corrosion resistance of new low-lead and lead-free brass alloys. How the heat treatment, processing and material composition relates to the microstructure and corrosion performance is not well understood. The present study aims to fill this knowledge gap by mapping stress-relieving annealing conditions and different standardised compositions to their respective microstructures and dezincification performance. It was found that loss of corrosion resistance was only the most severe for alloys with higher aluminium and iron content. These alloys displayed significant precipitation of intermetallic aluminium arsenide particles on grain boundaries, twins and lead particles, as well as the formation of β-phase along grain boundaries.

This paper is part of a Thematic Issue on Copper and its Alloys.     

Rapid exposure assessment of PSII herbicides in surface water using a novel chlorophyll a fluorescence imaging assay

Recently a new Maxi-Imaging-PAM (Max-I-PAM) instrument for phytotoxicity assessment via chlorophyll fluorescence imaging was introduced. This new instrument allows rapid detection of the effects of PS II inhibiting herbicides which are high use agricultural chemicals frequently detected in surface waters in Australia and elsewhere. Several studies have applied the new instrument for detection of phytotoxicants in water using microalgae suspensions; however, these use preliminary protocols and to date no validated method is available for high throughput testing of environmental samples in 96-well plates. Here we developed and applied a new protocol allowing dose-response assessment of four samples within 2 h (8 dilutions in duplicate). The technique was found to be sensitive, with a detection limit of 2.3 ng l(-1) for the herbicide diuron when testing solid phase extracts (SPE) of 1000 ml water samples, and reproducible both between experiments (coefficient of variation (CV)=0.30) and within the 96-well plate (CV=0.06). Relative potencies were determined for four reference PS II impacting herbicides (diuron>hexazinone>atrazine>simazine). Extracts from 1000 ml environmental samples and diuron spiked ultrapure water as well as passive sampler extracts were evaluated and good agreement was found between diuron equivalent concentrations calculated from bioassay results (DEQ(IPAM)) and DEQ(CHEM) values calculated from LCMS chemical analysis of the four reference compounds in the same samples. Overall, the technique provides a valuable bioanalytical tool for rapid and inexpensive effects-based assessment of PS II impacting herbicides in environmental mixtures.     

Green and Efficient Extraction Method to Determine Polyphenols in Cocoa and Cocoa Products

Cocoa and cocoa products have broad and well-proven health benefits, most of which are associated with the high antioxidant capacity of cocoa flavonoids. Most extraction methods for flavonoids in cocoa products use several steps including a defatting step and large amount of organic solvents. Moreover, they are labor-intensive and time-consuming. In this work, a pressurized hot water extraction (PHWE) method has been compared to conventional sonication extraction (CSE) method. The contribution of individual compounds to the total antioxidant capacity of the extracts was evaluated by developing an analytical technique consisting of high-performance liquid chromatography (HPLC) with photodiode array coupled to electrochemical and to charged aerosol detectors and HPLC-mass spectrometry for the confirmation of the identity of compounds present. Additionally, procyanidins were analyzed by fluorescence detection. PHWE turned out to be more efficient in extracting phenolics and methylxanthines, as compared to the conventional method, in addition to being more “green” in terms of using less organic solvents.     

Return to Religion? Predictors of Religious Change among Baby-Boomers in their Transition to Later Life

In this paper, we investigated the correlates of change in religiosity among babyboomers as they aged from their 50s to their 60s. Change was assessed as a function of cognitive and behavioral manifestations of religious involvement, early religious participation, and challenges that emerged over this period of life. Using qualitative and quantitative data from 599 respondents in the 2016 wave of the Longitudinal Study of Generations, we examined retrospectively assessed religious change over the previous ten years and the precipitating reasons for such change. Religiosity was most likely to remain stable, but a significant minority of the sample became more religious over the past ten years; reasons included a shift away from worldly concerns, coping with loss and health problems, and intergenerational continuity. Structural equation modeling found that early exposure to religion strengthened religiosity through its association with both stronger cognitive and behavioral aspects of religious involvement. Losing of a partner, experiencing economic decline, and having health problems either increased or stabilized religiosity, complementing results from qualitative responses. In general, religious change, when it did occur, was in a positive direction and served as a resource for dealing with health and social losses. We anticipate this trend to intensify as baby-boomers advance to even later stages of the life-course.     

Digital innovation in law dirms: The dominant logic under threat

This paper focuses on the impact of digitalization in the legal industry. The legal industry is highly institutionalized and has for long been unaffected by external changes. This has enabled the development of a strong institutional logic that has dictated homogeneous practices in law firms and limited their room for innovation. However, this seems about to change. Through a qualitative case study of the Swedish legal industry, this paper shows that new practices, enabled by digitalization, challenges common practices and puts the dominant logic under threat. By applying an institutional logics perspective to recent changes, this paper contrasts the enactment of the dominant logic with innovative practices and shows that digitalization has created institutional complexity, where digital pioneers respond to digital opportunities differently than incumbents. This paper also explains why and highlights the emergence of hybrid firms that successfully combine elements of the dominant logic with innovation. Consequently, this paper contributes to our understanding of digital innovation and digital transformation within highly institutional industries.     

Altered developmental timing in early life stages of Antarctic krill (Euphausia superba) exposed to p,p'-DDE

Persistent organic pollutants (POPs) are persistent, toxic and bioaccumulative anthropogenic organic chemicals, capable of undergoing long range environmental transport to remote areas including the Antarctic. p,p′-dichlorodiphenyl dichloroethylene (p,p′-DDE) has been identified as a dominant POP accumulating in Antarctic krill (Euphausia superba), which is a key Southern Ocean species. This study examined the developmental toxicity of p,p′-DDE via aqueous exposure to Antarctic krill larvae. p,p′-DDE exposure was found to stimulate developmental timing in the first three larval stages of Antarctic krill, while extended monitoring of larvae after a five day exposure period had ended, revealed delayed inhibitory responses during development to the fourth larval stage. Stimulatory responses were observed from the lowest p,p′-DDE body residue tested of 10.1 ± 3.0 μmol/kg (3.2 ± 0.95 mg/kg) preserved wet weight, which is comparable to findings for temperate species and an order of magnitude lower than the exposure level found to cause sublethal behavioural effects in Antarctic krill. The delayed responses included increased mortality, which had doubled in the highest p,p′-DDE treatment (95 ± 8.9% mortality at 20 μg/L p,p′-DDE) compared to the solvent control (44 ± 11% mortality) 2 weeks after end of exposure. Development of surviving metanauplius larvae to calyptopis 1 larvae was delayed by 2 days in p,p′-DDE exposed larvae compared with untreated larvae. Finally, the developmental success of surviving p,p′-DDE exposed larvae was reduced by 50 to 75% compared to the solvent control (100% developmental success). The lowest observed effect concentration for all delayed effects was 1 μg/L, the lowest exposure concentration tested. These findings demonstrate the importance of delayed and indirect effects of toxicant exposure. Further, the findings of this study are important for environmental risk assessment of POPs in the Southern Ocean ecosystem and strongly highlight the significance of developmental endpoints for ecotoxicological testing.     

Lipase-catalyzed methanolysis of triricinolein in organic solvent to produce 1,2(2,3)-diricinolein

The objective of this study was to find the optimal parameters for lipase-catalyzed methanolysis of triricinolein to produce 1,2(2,3)-diricinolein. Four different immobilized lipases were tested, Candida antarctica type B (CALB), Rhizomucor miehei (RML), Pseudomonas cepacia (PCL), and Penicillium roquefortii (PRL). n-Hexane and diisopropyl ether (DIPE) were examined as reaction media at three different water activities (a _w), 0.11, 0.53, and 0.97. The consumption of triricinolein and the formation of 1,2(2,3)-diricinolein, methyl ricinoleate, and ricinoleic acid were followed for up to 48 h. PRL gave the highest yield of 1,2(2,3)-diricinolein. Moreover, this lipase showed the highest specificity for the studied reaction, i.e., high selectivity for the reaction with triricinolein but low for 1,2(2,3)-diricinolein. Recoveries of 93 and 88% DAG were obtained using PRL in DIPE at a _w of 0.11 and 0.53, respectively. Further, NMR studies showed that a higher purity of the 1,2(2,3)-isomer vs. the 1,3-isomer was achieved at higher a _w (88% at a _w=0.53), compared to lower a _w (71% at a _w=0.11). The DAG obtained was acylated by the DAG acyltransferase from Arabidopsis thaliana. Therefore, this enzymatic product is a useful enzyme substrate for lipid biosynthesis. Accordingly, the use of PRL in DIPE at a _w 0.53 is considered optimal for the synthesis of 1,2(2,3)-diricinolein from triricinolein.     

Thermal and mechanical properties of solution polymerized segmented polyurethanes with butadiene soft segments

A series of HTPBD containing polyurethanes of high molecular weight have been synthesized in solution. The value of the soft segment T_g is very close to that of the free HTPBD and independent of hard segment content indicating complete or very nearly complete phase segregation. Since the hard segments of TDI/BDO are amorphous, the driving force for phase segregation must arise from the large degree of incompatibility between the polar hard segment and nonpolar soft segment. Furthermore, in these samples there is also no opportunity for hydrogen bonding between hard and soft segments to enhance compatibility.The values of the hard segment glass transition increase with the average hard segment length following a Fox-Flory type relationship. In contrast to the segment T_g observed in bulk polymerized samples, only a single hard segment T_g occurred in the present study. This indicates that the double T_g behaviour is a result of the heterogeneous nature of the bulk polymerization.With increasing hard segment content, the properties vary from soft to rigid elastomers, and rubber roughened plastics. This variation in properties is caused by changes in the sample morphology which depends upon the relative fractions of hard and soft segments. Mechanical properties show marked improvement over the corresponding bulk polymerized samples. Unlike polyester and polyether urethanes, these materials evidence no change in the soft segment T_g following thermal treatment and no effect of thermal history on the mechanical properties.