Expectations of Grassroots Community Leadership in Times of Normality and Crisis

The article compares the preferences of community members for the transformational and transactional leadership styles of grassroots leaders at times of normality with those during a crisis. A structured questionnaire was administered to members of a community that experienced security crises on the Lebanese border of Israel before the 2006 Lebanon War. It reveals differences in the dominance of preferred leadership styles depending on the type of situation – normality or crisis. The article discusses these differences, compares the findings with those of other studies and considers their practical implications.     

Computing in Totally Anonymous Asynchronous Shared Memory Systems

In the totally anonymous shared memory model of asynchronous distributed computing, processes have no identifiers and run identical programs. Moreover, processes have identical interface to the shared memory, and in particular, there are no single-writer registers. This paper assumes that processes do not fail, and the shared memory consists only of read/write registers, which are initialized to some default value. A complete characterization of the functions and agreement tasks that can be solved in this model is presented. Furthermore, it is shown that if a function is computable, then two registers are sufficient for some algorithm to compute it. Consensus is an important agreement task that can be computed. The paper proves logarithmic lower bounds on the number of registers and rounds needed for solving consensus in this model. A consensus protocol using a linear number of shared registers and rounds is also presented.     

Collision with friction; Part B: Poisson’s and Stornge’s hypotheses

In Part B of this paper, planar collision theories, counterparts of the theory associated with Newton’s hypotheses described in Part A, are developed in connection with Poisson’s and Stronge’s hypotheses. First, expressions for the normal and tangential impulses, the normal and tangential velocities of separation, and the change of the system mechanical energy are written for five types of collision. These together with Routh’s semigraphical method and Coulomb’s coefficient of friction are used to show that the algebraic signs of the four parameters introduced in Part A span the same five cases of system configuration of Part A. For each, α determines the type of collision which once found allows the evaluation of the normal and tangential impulses and ultimately the changes in the motion variables. The analysis of the indicated cases shows that for Poisson’s hypothesis, a solution always exists which is unique, coherent and energy-consistent. The same applies to Stronge’s hypothesis, however, for a narrower range of application. It is thus concluded that Poisson’s hypothesis is superior as compared with Newton’s and Stronge’s hypotheses.     

Multi-Layer Broadcasting over a Block Fading MIMO Channel

This paper introduces extensions for the broadcast approach for a multi-input multi-output (MIMO) block fading channel, with receiver only channel state information (CSI). Previous works have not been able to fully characterize the fundamental MIMO broadcasting upper bound. As it seems that analytical solution for this problem is quite difficult to achieve, we consider here sub-optimal schemes, for which achievable rates may be computed. In particular, finite level coding over a MIMO channel instead of continuous layering is analyzed, the expressions derived for the decoding probability regions allow numerical computation of finite level coding upper bounds. Noticing that the gains of two level coding over a MIMO channel are rather small, we consider sub-optimal techniques, which are more straightforward to implement. Among these techniques is the multiple-access channel (MAC) approach with single level coded streams, which is similar in concept to V-BLAST. Closed form expressions for probabilities of decoding regions here are derived, allowing numerical evaluation. We further consider multi-access permutation codes (MAPC). A Hadamard transform is compared with a suggested diagonal permutation code, which are shown to have similar performance, while diagonal permutation has lower implementation complexity. For all approaches, we derive information theoretic upper bounds of achievable rates.     

Information Rates Subject to State Masking

We consider the problem of rate-R, channel coding with causal/noncausal side information at the transmitter, under an additional requirement of minimizing the amount of information that can be learned from the channel output about the state sequence, which is defined in terms of the mutual information between the state sequence and the channel output sequence. A single-letter characterization is provided for the achievable region of pairs {(R, E)}. Explicit results for the Gaussian case (Costa's dirty-paper channel) are derived in full detail.     

Kinematics, dynamics and construction of a planarly actuated parallel robot

Kinematic and dynamic analysis of a parallel robot consisting of three planarly actuated links, is presented in this paper. Coordinated motion of three planar motors, connected to three fixed-length links, produces a six-degrees-of-freedom motion of an output link. Its extremely simple design along with much larger work volume than the commonly used parallel robots make this high performance-to-simplicity ratio robot very attractive. Experimental model verifies the unique combination of large work volume and high accuracy of this robot.     

Distribution of Salmonella typhimurium in romaine lettuce leaves

Leafy greens are occasionally involved in outbreaks of enteric pathogens. In order to control the plant contamination it is necessary to understand the factors that influence enteric pathogen-plant interactions. Attachment of Salmonella enterica serovar typhimurium to lettuce leaves has been demonstrated before; however, only limited information is available regarding the localization and distribution of immigrant Salmonella on the leaf surface. To extend our knowledge regarding initial pathogen-leaf interactions, the distribution of green-fluorescent protein-labeled Salmonella typhimurium on artificially contaminated romaine lettuce leaves was analyzed. We demonstrate that attachment of Salmonella to different leaf regions is highly variable; yet a higher attachment level was observed on leaf regions localized close to the petiole (7.7 log CFU g⁻¹) compared to surfaces at the far-end region of the leaf blade (6.2 log CFU g⁻¹). Attachment to surfaces located at a central leaf region demonstrated intermediate attachment level (7.0 log CFU g⁻¹). Salmonella displayed higher affinity toward the abaxial side compared to the adaxial side of the same leaf region. Rarely, Salmonella cells were also visualized underneath stomata within the parenchymal tissue, supporting the notion that this pathogen can also internalize romaine lettuce leaves. Comparison of attachment to leaves of different ages showed that Salmonella displayed higher affinity to older compared to younger leaves (1.5 log). Scanning electron microscopy revealed a more complex topography on the surface of older leaves, as well as on the abaxial side of the examined leaf tissue supporting the notion that a higher attachment level might be correlated with a more composite leaf landscape. Our findings indicate that initial attachment of Salmonella to romaine lettuce leaf depends on multiple plant factors pertaining to the specific localization on the leaf tissue and to the developmental stage of the leaf.     

Comments on using alternatives to normal theory statistics in social and behavioural science.

Comments on the article by M. A. Hunter and R. B. May (see record 1994-24054-001) on the myths and misconceptions of parametric and nonparametric statistics, particularly with reference to power, robustness, scale of measurement, the null hypothesis, and generality of application. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aroused versus calm positive affects as predictors of lipids.

Objective: The authors hypothesized that high-pleasure low-arousal (HPLA) would predict a subsequent decrease of low-density lipoprotein cholesterol (LDL-C) and triglycerides (TRI), as well as a subsequent increase of high-density lipoprotein cholesterol (HDL-C). The authors also hypothesized that high-pleasure high-arousal (HPHA) would have the opposite effects on these blood lipids, predicting a subsequent increase of LDL-C and TRI, and a decrease of HDL-C. Design: Participants were 990 male and 595 female apparently healthy employees who underwent a routine periodic health examination at two points in time, Time 1 (T1) and Time 2 (T2), about 24 months apart. Data were analyzed separately for the men and women, and the authors controlled for possible confounders shown in past research to be implicated with hyperlipidemia. Main Outcome Measures: HPHA and HPLA were assessed based on the Job-Related Affective Well-Being Scale, while LDL-C, TRI, and HDL-C were assessed based on fasting blood samples. Results: For the men, support for our hypotheses was found relative to HDL-C and TRI. The authors did not find support for our hypotheses for thee women. Conclusion: Our findings suggest that for men, the two types of positive affects may have opposite physiological consequences with respect to subsequent changes in blood lipid levels. (PsycINFO Database Record (c) 2010 APA, all rights reserved)