Diffusion and solubility of oxygen in silver

The diffusion and solubility of oxygen in Ag in the temperature range between 412 and 862 C was determined. The following interpolation formula was found for the solubility: L = 8.19.1/100.exp(-11 860/RT)Mol O2/g.At.Ag.at 1/.5. The process obeys the Sieverts square root law within the limits of error. The dissolution of oxygen in Ag may be accompanied by the dissociation of the oxygen molecules into atoms. The tests on Ag-foils reveal that below a temperature of about 500 C a higher solubility is simulated by the adsorption of oxygen. The diffusion coefficient of oxygen in silver obeys the following equation: D = 2.72.1/100.exp(-11 000/RT)sq cm/s. The relatively low activation energy of 11 kcal/g.At suggests that the diffusion of oxygen takes places over interstitial sites

Oral microbiota carriage in patients with multibracket appliance in relation to the quality of oral hygiene

Background: The present study aimed to investigate the prevalence of oral microbiota (Candida species (spp.), Streptococcus mutans, and Lactobacilli) in patients with multibracket (MB) appliances in relation to the quality of oral hygiene. Saliva and plaque samples were collected from three groups of 25 patients each (good oral hygiene (GOH), poor oral hygiene (POH), and poor oral hygiene with white spot lesions (POH/WSL)). Counts of colony forming units (CFU) of the investigated oral microbiota were compared using Chi-square and Mann–Whitney U tests. Results: Both saliva and plaque samples showed a high prevalence of Candida spp. in all patients (saliva: 73.4 %, plaque: 60.9 %). The main Candida species was C. albicans. The salivary CFU of Candida spp. in the GOH group was significantly lower than that in the POH group (p?=?0.045) and POH/WSL group (p?=?0.011). S. mutans was found in the saliva and plaque samples of all patients. Lactobacilli were found in the saliva samples of all patients and in 90.7 % of the plaque samples. In the saliva samples, the CFU of Lactobacilli were more numerous in the POH and POH/WSL groups than in the GOH group (p?=?0.047). Conclusions: The investigated sample of patients showed a high carriage of oral Candida spp. Patients with WSL formation during MB appliance treatment exhibited higher counts of Candida and Lactobacilli compared with patients with good oral hygiene. Independent of oral hygiene quality, S. mutans was detected in all patients

Bilateralizing multilateral aid? Aid allocation by World Bank trust funds

Over the last decade, donors of foreign aid quadrupled their annual contributions to trust funds at the World Bank. Concerns have been raised that trust fund aid may undermine the incentives associated with IDA s performance-oriented aid allocation. Moreover, the earmarking of contributions to donors preferred recipient countries might bilateralize multilateral aid, potentially to the detriment of aid effectiveness. Using new data on World Bank trust fund disbursements for the 2002-2012 period, we test whether trust fund aid substitutes for IDA inflows, and, as official narratives suggest, for other aid inflows. We also investigate the bilateralization hypothesis by comparing multilateral core aid to trust fund disbursements. Trust fund aid is generally not allocated according to World Bank s Country Policy and Institutional Assessment (CPIA) index, which could undermine the incentives generated of the IDA allocation mechanism. This result is confirmed when we consider the health, education, and environment sector separately using sector-specific CPIA scores and IDA aid. We do not find systematic evidence that trust funds are to a larger degree motivated by political and economic motives

Geopolitics, Aid and Growth

We investigate the effects of short-term political motivations on the effectiveness of foreign aid. Specifically, we test whether the effect of aid on economic growth is reduced by the share of years a country has served on the United Nations Security Council (UNSC) in the period the aid has been committed, which provides quasi-random variation in aid. Our results show that the relationship of aid with growth is significantly lower when aid has been committed during a country’s tenure on the UNSC. We derive two conclusions from this. First, short-term political favoritism reduces growth. Second, political interest variables are inadequate as instruments for overall aid, raising doubts about a large number of results in the aid effectiveness literature

The Effects of Trade, Aid, and Investment on China's Image in Developing Countries

One goal of China’s Go Out policy is to create goodwill in countries around the world. At the same time, China’s growing economic engagement has provoked much criticism. This paper is the first to study whether these activities change the attitudes of individuals in developing countries towards China at both the national and subnational level. Using repeated cross-sectional survey data from the Latinobarómetro, we analyze whether and how growing amounts of exports, foreign aid, and foreign direct investment from China to Latin America affect opinions on China within 18 Latin American countries over the 2002-2013 period. We run instrumental-variables regressions by exploiting exogenous variation in the supply of Chinese exports, aid, and investment proxied by China’s market penetration of developing countries outside Latin America. In contrast to the widespread criticism, we do not find evidence that China’s growing economic activities in the respective countries deteriorate average attitudes towards China — neither at the national nor the provincial level. However, our results show that the young, educated, and economically privileged population develops more positive views of China. We interpret this as evidence that China’s economic engagement creates winners and losers

A quasi classical approach to fully differential ionization cross sections

A classical approximation to time dependent quantum mechanical scattering in the M\o{}ller formalism is presented. Numerically, our approach is similar to a standard Classical-Trajectory-Monte-Carlo calculation. Conceptually, however, our formulation allows one to release the restriction to stationary initial distributions. This is achieved by a classical forward-backward propagation technique. As a first application and for comparison with experiment we present fully differential cross sections for electron impact ionization of atomic hydrogen in the Erhardt geometry.Comment: 6 pages, 2 figure

A semi-classical over-barrier model for charge exchange between highly charged ions and one-optical electron atoms

Absolute total cross sections for electron capture between slow, highly charged ions and alkali targets have been recently measured. It is found that these cross sections follow a scaling law with the projectile charge which is different from the one previously proposed basing on a classical over-barrier model (OBM) and verified using rare gases and molecules as targets. In this paper we develop a "semi-classical" (i.e. including some quantal features) OBM attempting to recover experimental results. The method is then applied to ion-hydrogen collisions and compared with the result of a sophisticated quantum-mechanical calculation. In the former case the accordance is very good, while in the latter one no so satisfactory results are found. A qualitative explanation for the discrepancies is attempted.Comment: RevTeX, uses epsf; 6 pages text + 3 EPS figures Journal of Physics B (scehduled March 2000). This revision corrects fig.

Hurst's Rescaled Range Statistical Analysis for Pseudorandom Number Generators used in Physical Simulations

The rescaled range statistical analysis (R/S) is proposed as a new method to detect correlations in pseudorandom number generators used in Monte Carlo simulations. In an extensive test it is demonstrated that the RS analysis provides a very sensitive method to reveal hidden long run and short run correlations. Several widely used and also some recently proposed pseudorandom number generators are subjected to this test. In many generators correlations are detected and quantified.Comment: 12 pages, 12 figures, 6 tables. Replaces previous version to correct citation [19

The Gargantuan Gap : A Model of User Reactions Toward and Beliefs About Employee Selection Procedures

Thesis (Ph.D.)--Michigan State University. Psychology - Doctor of Philosophy, 2024Candidate results from multiple employee selection procedures are most often combined clinically using hiring managers\u2019 judgment, but evidence suggests this approach attenuates predictive validity compared to mechanical data combination approaches due to hiring managers\u2019 misconceptions about selection procedures. The present research proposes and tests a model that explains how and why hiring managers determine the extent to which they will utilize candidate results from various selection procedures or sources of candidate information. Specifically, the model posits that utilization is driven by user beliefs about the predictiveness and fairness of procedures, which are in turn informed by nine dimensions of \u201cuser reactions\u201d or perceptions of properties of predictor methods (procedural autonomy, evaluation autonomy, fidelity, fakability, evaluation consistency, and transparency) and predictor constructs (job relatedness, malleability, and development equity). Study 1 tested the model by asking a sample of hiring managers to view and rate selection procedures manipulated into nine predictor method/construct combinations. Results indicated that users\u2019 predictiveness beliefs are a stronger driver of utilization than fairness beliefs; additionally, most dimensions of user reactions predicted utilization intentions in the hypothesized direction. Study 2 evaluated the efficacy of autonomy-based interventions by having a sample of hiring managers view and rate a structured interview or computerized assessment manipulated into high and low levels of autonomy. Results suggested that slightly increasing hiring manager autonomy within standardized selection procedures led to increases in predictiveness beliefs and utilization intentions. Findings have implications for designing selection procedures and tailoring hiring manager communication and training efforts, both with the goal of encouraging utilization of more valid predictors in employee selection decision-making contexts.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references

Electron impact double ionization of helium from classical trajectory calculations

With a recently proposed quasiclassical ansatz [Geyer and Rost, J. Phys. B 35 (2002) 1479] it is possible to perform classical trajectory ionization calculations on many electron targets. The autoionization of the target is prevented by a M\o{}ller type backward--forward propagation scheme and allows to consider all interactions between all particles without additional stabilization. The application of the quasiclassical ansatz for helium targets is explained and total and partially differential cross sections for electron impact double ionization are calculated. In the high energy regime the classical description fails to describe the dominant TS1 process, which leads to big deviations, whereas for low energies the total cross section is reproduced well. Differential cross sections calculated at 250 eV await their experimental confirmation.Comment: LaTeX, 22 pages, 10 figures, submitted to J. Phys.