Encryption methods using formal power series rings

Recently there has been a great deal of work on noncommutative algebraic cryptography. This involves the use of noncommutative algebraic objects as the platforms for encryption systems. Most of this work, such as the Anshel-Anshel-Goldfeld scheme, the Ko-Lee scheme and the Baumslag-Fine-Xu Modular group scheme use nonabelian groups as the basic algebraic object. Some of these encryption methods have been successful and some have been broken. It has been suggested that at this point further pure group theoretic research, with an eye towards cryptographic applications, is necessary.In the present study we attempt to extend the class of noncommutative algebraic objects to be used in cryptography. In particular we explore several different methods to use a formal power series ring R && x1; :::; xn && in noncommuting variables x1; :::; xn as a base to develop cryptosystems. Although R can be any ring we have in mind formal power series rings over the rationals Q. We use in particular a result of Magnus that a finitely generated free group F has a faithful representation in a quotient of the formal power series ring in noncommuting variables.

For public service or money: Understanding geographical imbalances in the health workforce in Ethiopia

Geographical imbalances in the health workforce have been a consistent feature of nearly all health systems, and especially in developing countries. In this paper we investigate the willingness to work in a rural area among final year nursing and medical students in Ethiopia. Analyzing data obtained from contingent valuation questions, we find that household consumption and the student s motivation to help the poor, which is our proxy for intrinsic motivation, are the main determinants of willingness to work in a rural area. We investigate whoe is willing to help the poor and find that women are significantly more likely than men. Other variables, including a rich set of psychosocial characteristics, are not significant. Finally, we carry out some simulation on how much it would cost to make the entire cohort of starting nurses and doctors chooseto take up a rural post.

La dimensió social del moviment priscil·lianista en el context de l'antiguitat tardana. Heretgia, lluita contra la institucionalització eclesiàstica i contestació social.

L'any 385, Priscil·lià i la resta del grup priscil·lianista era condemnat a la ciutat de Trèveris i, fruit de la ingerència determinant de l'usurpador Magne Màxim, es convertia en el primer heretge ajusticiat pel poder secular en nom de l'Església. Els fets de Trèveris, per bé que van significar el final de la disputa entre dos grups amb posicions antagòniques vers les característiques del nou cristianisme institucionalitzat, no van aconseguir acabar amb el priscil·lianisme. El moviment perdurà, especialment a la província de la Gallaecia, i Priscil·lià va esdevenir venerat com màrtir. L'Església, mentrestant, es fracturava per culpa de la competència jurisdiccional entre la institució clerical i el poder imperial. Aquest treball intenta ser un estat de la qüestió respecte a la dimensió social d'un moviment que, més enllà de l'eterna discussió entre la seva possible catalogació com a ortodòxia o heterodòxia, intenta contextualitzar el priscil·lianisme en el seu marc històric i els convulsos anys de les transformacions de l'antiguitat tardana.

The influence of decision-maker effort and case complexity on appealed rulings subject to multi-categorical selection

This study extends the standard econometric treatment of appellate court outcomes by 1) considering the role of decision-maker effort and case complexity, and 2) adopting a multi-categorical selection process of appealed cases. We find evidence of appellate courts being affected by both the effort made by first-stage decision makers and case complexity. This illustrates the value of widening the narrowly defined focus on heterogeneity in individual-specific preferences that characterises many applied studies on legal decision-making. Further, the majority of appealed cases represent non-random sub-samples and the multi-categorical selection process appears to offer advantages over the more commonly used dichotomous selection models.

English as a medium of instruction in teaching other languages: attitudes and practices

Internationalisation of HE and emergence of English as a global academic lingua franca used by people who share neither a common native tongue nor cultural and educational background have not only offered more opportunities but also raised challenges. According to recent European surveys, the percentage of pupils attaining the level of independent user in English varies from 14% to 82%, which evidences the potential and the complexity for English as a medium of instruction at tertiary level. This study aims to present the model of foreign language instruction at Vytautas Magnus University where one third of 30 languages are taught through English. It investigates the attitudes and practices of teachers in delivering their English-medium language courses by discussing the questions whether teaching other languages through English is psychologically, culturally and educationally preferable for teachers and students, whether it can limit the content taught and require a special methodology, how the teaching process changes with multiple languages used in the classroom and what level of English is necessary for teachers and students to ensure high quality of English-medium language teaching. The study is based on qualitative methodology with 12 language teachers participating as respondents. The results reveal areas in need of improvement.

Balancing effluent quality, economic cost and greenhouse gas emissions during the evaluation of (plant-wide) control/operational strategies in WWTPs

The objective of this paper was to show the potential additional insight that result from adding greenhouse gas (GHG) emissions to plant performance evaluation criteria, such as effluent quality (EQI) and operational cost (OCI) indices, when evaluating (plant-wide) control/operational strategies in wastewater treatment plants (WWTPs). The proposed GHG evaluation is based on a set of comprehensive dynamic models that estimate the most significant potential on-site and off-site sources of CO2, CH4 and N2O. The study calculates and discusses the changes in EQI, OCI and the emission of GHGs as a consequence of varying the following four process variables: (i) the set point of aeration control in the activated sludge section; (ii) the removal efficiency of total suspended solids (TSS) in the primary clarifier; (iii) the temperature in the anaerobic digester; and (iv) the control of the flow of anaerobic digester supernatants coming from sludge treatment. Based upon the assumptions built into the model structures, simulation results highlight the potential undesirable effects of increased GHG production when carrying out local energy optimization of the aeration system in the activated sludge section and energy recovery from the AD. Although off-site CO2 emissions may decrease, the effect is counterbalanced by increased N2O emissions, especially since N2O has a 300-fold stronger greenhouse effect than CO2. The reported results emphasize the importance and usefulness of using multiple evaluation criteria to compare and evaluate (plant-wide) control strategies in a WWTP for more informed operational decision making

Prehospital ticagrelor in ST-segment elevation myocardial infarction

Background:The direct-acting platelet P2Y receptor antagonist ticagrelor can reduce the incidence of major adverse cardiovascular events when administered at hospital admission to patients with ST-segment elevation myocardial infarction (STEMI). Whether prehospital administration of ticagrelor can improve coronary reperfusion and the clinical outcome is unknown. Methods: We conducted an international, multicenter, randomized, double-blind study involving 1862 patients with ongoing STEMI of less than 6 hours' duration, comparing prehospital (in the ambulance) versus in-hospital (in the catheterization laboratory) treatment with ticagrelor. The coprimary end points were the proportion of patients who did not have a 70% or greater resolution of ST-segment elevation before percutaneous coronary intervention (PCI) and the proportion of patients who did not have Thrombolysis in Myocardial Infarction flow grade 3 in the infarct-related artery at initial angiography. Secondary end points included the rates of major adverse cardiovascular events and definite stent thrombosis at 30 days. Results: The median time from randomization to angiography was 48 minutes, and the median time difference between the two treatment strategies was 31 minutes. The two coprimary end points did not differ significantly between the prehospital and in-hospital groups. The absence of ST-segment elevation resolution of 70% or greater after PCI (a secondary end point) was reported for 42.5% and 47.5% of the patients, respectively. The rates of major adverse cardiovascular events did not differ significantly between the two study groups. The rates of definite stent thrombosis were lower in the prehospital group than in the in-hospital group (0% vs. 0.8% in the first 24 hours; 0.2% vs. 1.2% at 30 days). Rates of major bleeding events were low and virtually identical in the two groups, regardless of the bleeding definition used