A Dual Digraph Approach for Leaderless Atomic Broadcast (Extended Version)

Many distributed systems work on a common shared state; in such systems, distributed agreement is necessary for consistency. With an increasing number of servers, these systems become more susceptible to single-server failures, increasing the relevance of fault-tolerance. Atomic broadcast enables fault-tolerant distributed agreement, yet it is costly to solve. Most practical algorithms entail linear work per broadcast message. AllConcur -- a leaderless approach -- reduces the work, by connecting the servers via a sparse resilient overlay network; yet, this resiliency entails redundancy, limiting the reduction of work. In this paper, we propose AllConcur+, an atomic broadcast algorithm that lifts this limitation: During intervals with no failures, it achieves minimal work by using a redundancy-free overlay network. When failures do occur, it automatically recovers by switching to a resilient overlay network. In our performance evaluation of non-failure scenarios, AllConcur+ achieves comparable throughput to AllGather -- a non-fault-tolerant distributed agreement algorithm -- and outperforms AllConcur, LCR and Libpaxos both in terms of throughput and latency. Furthermore, our evaluation of failure scenarios shows that AllConcur+'s expected performance is robust with regard to occasional failures. Thus, for realistic use cases, leveraging redundancy-free distributed agreement during intervals with no failures improves performance significantly.Comment: Overview: 24 pages, 6 sections, 3 appendices, 8 figures, 3 tables. Modifications from previous version: extended the evaluation of AllConcur+ with a simulation of a multiple datacenters deploymen

LEADERSHIP EMPOWERMENT BEHAVIOUR, WORK ENGAGEMENT AND TURNOVER INTENTION: THE ROLE OF PSYCHOLOGICAL EMPOWERMENT

Research purpose: The purpose of this study was to investigate the relationship between leadership empowerment behavior, psychological empowerment, work engagement and turnover intention. The study further investigated whether psychological empowerment mediates the relationship between leadership empowerment behavior and turnover intention and work engagement respectively.Research design, approach and method: A cross-sectional survey design was used with a convenience sample (N = 322). Confirmatory factor analysis was used to test whether the measures of the constructs were consistent with the understanding of the nature of the constructs and to test whether the data fitted the hypothesized measurement model. Structural Equation Modeling (SEM) was used to examine the structural relationships between the constructs.Measuring instruments: The Leader Empowering Behavior Questionnaire, Measuring Empowerment, Work Engagement and Turnover Intention scales were administered.Main findings: The results showed significant positive relationships between leadership empowerment behavior, psychological empowerment, work engagement and a negative correlation with turnover intention. Leadership empowerment behavior affected work engagement through psychological empowerment.Practical implications: It is recommended that leadership discussions, training programs and individual coaching about leadership empowering behavior takes place

Hyperfine, rotational and Zeeman structure of the lowest vibrational levels of the 87^{87}Rb2_2 \tripletex state

We present the results of an experimental and theoretical study of the electronically excited \tripletex state of $^{87}$Rb$_2$ molecules. The vibrational energies are measured for deeply bound states from the bottom up to $v'=15$ using laser spectroscopy of ultracold Rb$_2$ Feshbach molecules. The spectrum of each vibrational state is dominated by a 47\,GHz splitting into a \cog and \clg component caused mainly by a strong second order spin-orbit interaction. Our spectroscopy fully resolves the rotational, hyperfine, and Zeeman structure of the spectrum. We are able to describe to first order this structure using a simplified effective Hamiltonian.Comment: 10 pages, 7 figures, 2 table

Oral squamous cell carcinoma in non-smoking and non-drinking patients

INTRODUCTION: Of the many different factors associated with an increased risk for oral squamous cell carcinoma (SCC), tobacco and alcohol seems to be the best studied. The aim of the current study was to evaluate the clinicopathologic characteristics of patients without the mentioned risk factors. Patients and Methods From 278 patients (159 male and 119 female patients) with oral SCC, 67 patients were without a history of tobacco or alcohol use. The minimum follow-up time was 12 months. RESULTS: Of the 67 patients, 45 (67.2%) were women and the mean age was 70 years. The most common tumor sites were mandibular alveolar ridge: 22 and maxilla: 18. Fifteen patients experienced a recurrence and 10 developed lymph node metastases during the follow-up period. CONCLUSION: The group of patients without tobacco and alcohol use tends to have a higher female portion, higher potion of patients being over 70 years and a higher number of oral maxillary SCC

TGF beta 1 attenuates expression of prolactin and IGFBP-1 in decidualized endometrial stromal cells by both SMAD-dependent and SMAD-independent pathways

Background: Decidualization (differentiation) of the endometrial stromal cells during the secretory phase of the menstrual cycle is essential for successful implantation. Transforming Growth Factor beta 1 (TGF beta 1) canonically propagates its actions via SMAD signalling. A role for TGF beta 1 in decidualization remains to be established and published data concerning effects of TGF beta 1 on markers of endometrial decidualization are inconsistent. Methodology/Principal Findings: Non-pregnant endometrial stromal cells (ESC) and first trimester decidual stromal cells (DSC) were cultured in the presence or absence of a decidualizing stimulus. Incubation of ESCs with TGF beta 1 (10 ng/ml) down-regulated the expression of transcripts encoding the decidual marker proteins prolactin (PRL), insulin-like growth factor binding protein-1 (IGFBP-1) and tissue factor (TF). TGF beta 1 also inhibited secretion of PRL and IGFBP-1 proteins by ESCs and surprisingly this response preceded down-regulation of their mRNAs. In contrast, DSCs were more refractory to the actions of TGF beta 1, characterized by blunted and delayed down-regulation of PRL, IGFBP-1, and TF transcripts, which was not associated with a significant reduction in secretion of PRL or IGFBP-1 proteins. Addition of an antibody directed against TGF beta 1 increased expression of IGFBP-1 mRNA in decidualised cells. Knockdown of SMAD 4 using siRNAs abrogated the effect of TGF beta 1 on expression of PRL in ESCs but did not fully restore expression of IGFBP-1 mRNA and protein. Conclusions/Significance: TGF beta 1 inhibits the expression and secretion of decidual marker proteins. The impact of TGF beta 1 on PRL is SMAD-dependent but the impact on IGFBP1 is via an alternative mechanism. In early pregnancy, resistance of DSC to the impact of TGF beta 1 may be important to ensure tissue homeostasis

The double-gap life expectancy forecasting model

Life expectancy is highly correlated over time among countries and between males and females. These associations can be used to improve forecasts. Here we propose a method for forecasting female life expectancy based on analysis of the gap between female life expectancy in a country compared with the record level of female life expectancy in the world. Second, to forecast male life expectancy, the gap between male life expectancy and female life expectancy in a country is analysed. We present these results for various developed countries. We compare our results with forecasts based on the Lee–Carter approach and the Cairns–Blake–Dowd strategy. We focus on forecasting life expectancy at age 0 and remaining life expectancy at age 65