Free energies, vacancy concentrations and density distribution anisotropies in hard--sphere crystals: A combined density functional and simulation study

We perform a comparative study of the free energies and the density distributions in hard sphere crystals using Monte Carlo simulations and density functional theory (employing Fundamental Measure functionals). Using a recently introduced technique (Schilling and Schmid, J. Chem. Phys 131, 231102 (2009)) we obtain crystal free energies to a high precision. The free energies from Fundamental Measure theory are in good agreement with the simulation results and demonstrate the applicability of these functionals to the treatment of other problems involving crystallization. The agreement between FMT and simulations on the level of the free energies is also reflected in the density distributions around single lattice sites. Overall, the peak widths and anisotropy signs for different lattice directions agree, however, it is found that Fundamental Measure theory gives slightly narrower peaks with more anisotropy than seen in the simulations. Among the three types of Fundamental Measure functionals studied, only the White Bear II functional (Hansen-Goos and Roth, J. Phys.: Condens. Matter 18, 8413 (2006)) exhibits sensible results for the equilibrium vacancy concentration and a physical behavior of the chemical potential in crystals constrained by a fixed vacancy concentration.Comment: 17 pages, submitted to Phys. Rev.

Constant elasticity of substitution functions for energy modeling in general equilibrium integrated assessment models:a critical review and recommendations

Applying constant elasticity of substitution (CES) functions in general equilibrium integrated assessment models (GE-IAMs) for the substitution of technical factor inputs (e.g., replacing fossil fuels) fails to match historically observed patterns in energy transition dynamics. This method of substitution is also very sensitive to the structure of CES implementation (nesting) and parameter choice. The resulting methodology-related artifacts are (i) the extension of the status quo technology shares for future energy supply relying on fossil fuels with carbon capture, biomass, and nuclear; (ii) monotonically increasing marginal abatement costs of carbon; and (iii) substitution of energy with non-physical inputs (e.g., knowledge and capital) without conclusive evidence that this is possible to the extent modeled. We demonstrate these issues using simple examples and analyze how they are relevant in the case of four major CES-based GE-IAMs. To address this, we propose alternative formulations either by opting for carefully applied perfect substitution for alternative energy options or by introducing dynamically variable elasticity of substitution as a potential intermediate solution. Nevertheless, complementing the economic analysis with physical modeling accounting for storage and resource availability at a high resolution spatially and temporally would be preferable

Tanning Bed Legislation for Minors: A Comprehensive International Comparison

Tanning beds have been classified as carcinogenic to humans. As a result, many countries have enacted laws regulating the use of commercial tanning beds, including bans for minors. However, there is no international overview of the current legal status of access restrictions for minors that provides details on their specific design regarding age limits and possible exceptions to the statutory regulation. Therefore, we performed a comprehensive web search of current tanning bed legislation for minors on the three continents North America, Australia, and Europe. Our findings regarding the existence and concrete design of access restrictions are presented graphically, using maps. We found a wide variety of different legislations. In Australia, a total ban on tanning beds exists, while in New Zealand, tanning bed use is banned for minors. In Europe, about half of the countries have implemented a strict ban for minors. In North America, we found differences in the age limit for access restrictions between the states, provinces, and territories for those regions that implemented a ban for minors. In the United States, some states have rather “soft bans” that allow use by minors with different types of parental consent. The patchwork in legislation calls for harmonization. Therefore, our comparison is an important starting point for institutions such as the World Health Organization or the European Commission to advance their goals toward a harmonization of tanning bed legislation in general and for minors in particular

Wie Plausibel Ist Die Erfassung Von Bräunungssucht? – Ein Multimethodischer Ansatz Zur Evaluation Eines Neuen Instruments

Einleitung: Ultraviolette (UV) Strahlung – sei sie natürlich oder künstlich – kann zu Hautkrebs führen. In Verbindung mit Solarien, einer Hauptquelle künstlicher UV-Strahlung, wird häufig auf die Möglichkeit der Entstehung einer Bräunungssucht (oft auch „Tanorexie“) hingewiesen. Bisherige Instrumente zum Screening auf eine solche Bräunungssucht ergaben sich jedoch als nicht valide. Aus diesem Grund war es unser Ziel, ein in den USA neu entwickeltes Instrument, den Behavioral Addiction Indoor Tanning Screener (BAITS), auf Validität und Reliabilität zu testen. Methodik: Der BAITS ist ein kurzes Screeninginstrument, welches aus sieben Items (Antwortkategorien: ja/nein) besteht. Die englischsprachige Itembatterie wurde in einer fünfstufigen Prozedur ([1] Übersetzung ins Deutsche, [2] Expert Panel, [3] Rückübersetzung ins Englische, [4] kognitive Interviews, [5] Erstellung der finalen Version) übersetzt. Zur Überprüfung der Validität und Reliabilität zogen wir die Daten der ersten Welle des Nationalen Krebshilfe Monitorings zur Solariennutzung (NCAM) bestehend aus einem kognitiven Pretest (n = 15) und einer bundesweiten Repräsentativbefragung (n = 3.000) heran. Ergebnisse: Der kognitive Pretest ergab eine leichte Veränderung in der Formulierung eines Items. Insgesamt wurden in der bundesweiten Befragung 19,7% der aktuellen und 1,8% der ehemaligen Nutzer von Solarien positiv auf Symptome einer möglichen Bräunungssucht gescreent. Es fanden sich signifikante Zusammenhänge zwischen Solariennutzungsparametern und dem BAITS (Kriteriumsvalidität). Die interne Konsistenz (Reliabilität) ergab sich ebenfalls als gut (Kuder-Richardson-20 = 0,854) und der BAITS erwies sich als homogenes Konstrukt (Konstruktvalidität). Schlussfolgerungen: Verglichen mit anderen Kurzinstrumenten zur Messung von Symptomen einer möglichen Bräunungssucht ergab sich der BAITS als valideres und reliableres Tool. Aufgrund seiner Kürze und der binären Items ist er auch in großen Surveys einfach einzusetzen