Self-esteem development from young adulthood to old age: A cohort-sequential longitudinal study.

The authors examined the development of self-esteem from young adulthood to old age. Data came from the Americans’ Changing Lives study, which includes 4 assessments across a 16-year period of a nationally representative sample of 3,617 individuals aged 25 years to 104 years. Latent growth curve analyses indicated that self-esteem follows a quadratic trajectory across the adult life span, increasing during young and middle adulthood, reaching a peak at about age 60 years, and then declining in old age. No cohort differences in the self-esteem trajectory were found. Women had lower self-esteem than did men in young adulthood, but their trajectories converged in old age. Whites and Blacks had similar trajectories in young and middle adulthood, but the self-esteem of Blacks declined more sharply in old age than did the self-esteem of Whites. More educated individuals had higher self-esteem than did less educated individuals, but their trajectories were similar. Moreover, the results suggested that changes in socioeconomic status and physical health account for the decline in self-esteem that occurs in old age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inverse 1-center location problems with edge length augmentation on trees

This paper considers the inverse 1-center location problem with edge length augmentation on a tree network T with n + 1 vertices. The goal is to increase the edge lengths at minimum total cost subject to given modification bounds such that a predetermined vertex s becomes an absolute 1-center under the new edge lengths. Using a set of suitably extended AVL-search trees we develop a combinatorial algorithm which solves the inverse 1-center location problem with edge length augmentation in O(n log n) time. Moreover, it is shown that the problem can be solved in O(n) time if all the cost coefficients are equal.     

Analysis of the diffusive mass transport in the anode side porous backing layer of a direct methanol fuel cell

In this work we present an analysis of the mass transport in the anode side porous backing layer of a direct methanol fuel cell (DMFC). The effective transport coefficient of different backing layers at various compressions was measured and compared to two different literature models and a single particle random walk simulation which accounts for details of the geometrical fibre microstructure. Based on the measured values of the effective transport coefficient limiting current densities for diffusive transport were calculated taking into account geometric boundary conditions and anisotropic and inhomogeneous backing layer properties. Comparison with the measured values for the limiting current in fuel cell operation shows qualitative agreement. A systematic underestimation indicates that also other transport processes contribute significantly to the mass transfer at the used experimental setup.     

Reconsidering the quantitative analysis of organic carbon concentrations in size exclusion chromatography

The evaluation of the molecular size distribution of natural organic matter (NOM) in aquatic environments via size exclusion chromatography (SEC) is important for the understanding of environmental processes such as nutrient cycling and pollutant transport as well as of technical water treatment processes. The use of organic carbon (OC) detectors has become popular in recent studies due to improved availability and quantification possibilities, which supposedly are superior to those of ultraviolet (UV) detectors. A set of 12 NOM samples was used to demonstrate the limitations of online OC detection (OCD) when analyzing complex aquatic organic matter. A novel evaluation approach for SEC data is introduced by combining the information from UV absorbance (UVA) and OCD chromatograms as well as offline total OC (t-OC) and dissolved OC-specific UVA (SUVA) measurements. It could be shown that about 70% of certain OC components were not detected with the OCD system used in this study. For the investigated samples, these types of carbon accounted for up to 72% of the t-OC, i.e. for such NOM samples quantification by OCD is not possible or at least highly questionable. The addition of an oxidant improved the overall oxidation efficiency only slightly. Most likely NOM that predominantly consists of polysaccharides and features a nominal molecular weight of 150 kg/mol or more was responsible for low OCD yields. For future applications, a further improvement of the OCD system would be worthwhile so that quantitative analytical data on the molecular size distribution of NOM and its structural characteristics such as the SUVA distribution can be obtained.     

Challenges and Progress in High‐Throughput Screening of Polymer Mechanical Properties by Indentation

Depth‐sensing or instrumented indentation is an experimental characterization approach well‐suited for high‐throughput investigation of mechanical properties of polymeric materials. This is due to both the precision of force and displacement, and to the small material volumes required for quantitative analysis. Recently, considerable progress in the throughput (number of distinct material samples analyzed per unit time) of indentation experiments has been achieved, particularly for studies of elastic properties. Future challenges include improving the agreement between various macroscopic properties (elastic modulus, creep compliance, loss tangent, onset of nonlinear elasticity, energy dissipation, etc.) and their counterpart properties obtained by indentation. Sample preparation constitutes a major factor for both the accuracy of the results and the speed and efficiency of experimental throughput. It is important to appreciate how this processing step may influence the mechanical properties, in particular the onset of nonlinear elastic or plastic deformation, and how the processing may affect the agreement between the indentation results and their macroscopic analogues.     

Bolus ingestion of white and green tea increases the concentration of several flavan‐3‐ols in plasma,but does not affect markers of oxidative stress in healthy non‐smokers

White tea (WT) is rich in flavan‐3‐ols as green tea (GT) and might provide health protective effects due to the strong antioxidant properties of flavan‐3‐ols. Since intervention studies with WT are lacking, we evaluated the effects of WT consumption on antioxidant status, antioxidant capacity and biomarkers of oxidative stress compared to water and GT. After an overnight fast, 70 healthy non‐smokers were randomized to consume 600 mL of WT, GT or water (control). Plasma (epi‐)catechin and epi(gallo)catechingallate, antioxidant capacity (Folin assay, trolox equivalent antioxidant capacity test), 8‐iso‐prostaglandin F_2α, ascorbic acid and uric acid were determined before and several times within 8 h after consumption. DNA strand breaks were measured in vivo and ex vivo (H₂O₂ stimulation) in leukocytes. Plasma flavan‐3‐ols significantly increased after WT and GT ingestion. Trolox equivalent antioxidant capacity was lower after 5 h in controls versus WT (p=0.031) and GT (p=0.005). Folin‐Ciocalteu reducing capacity, ascorbic and uric acid as well as markers of oxidative stress (8‐iso‐prostaglandin‐F_2α, DNA strand breaks) were not affected by the beverages. A short‐term increase of catechins does not change plasma antioxidant capacity in healthy subjects. Conclusions with respect to health protective effects of WT and GT on the basis of these biomarkers can, thus, not be drawn.     

Verfahren zur Verl?ngerung der Haltbarkeit von Konsummilch und ihre stofflichen Ver?nderungen: ESL-Milch

Die ESL-Technologie stellt nach der H-Milch eine weitere Entwicklung mit hohem Zusatznutzen in Bezug auf Haltbarkeit und Vorratshaltung dar, wovon sowohl Handel als auch Verbraucher gleicherma?en profitieren k?nnen. Im Vergleich zum herk?mmlich pasteurisierten Produkt bringt das ESL-Konzept entscheidende Vorteile hinsichtlich der Haltbarkeit der Milch mit sich, wirkt sich dabei aber kaum oder nur geringfügig auf die für den Verbraucher entscheidenden bzw. wertrelevanten Produkteigenschaften aus. ESL-Produkte sind in diesem Sinne also nicht nur „l?nger haltbar”, sondern unserer Einsch?tzung nach auch „l?nger frisch”. Dass gerade die Produktcharakteristika der ESL-Milch den Wünschen der Verbraucher entgegenkommen, zeigt sich an der stetig steigenden Nachfrage nach diesen Produkten und dem damit einhergehenden Absatzrückgang von herk?mmlich pasteurisierter Frischmilch. Die Verbraucher haben also durch ihr Kaufverhalten in den letzten Jahren bereits deutlich gemacht, dass sie der ESL-Milch durchaus positiv gegenüberstehen und sich mit diesem Produktkonzept keineswegs „get?uscht” fühlen, was die hier zusammengefassten Fakten eindeutig untermauern.