Liking and attributions of motives as mediators of the relationships between individuals' reputations, helpful behaviors and raters' reward decisions.

Two studies investigated the mediating effects of liking and attributions of motives on the relationship between a ratee's reputation and helpful behaviors and raters' reward decisions. During managerial simulations, raters evaluated individuals after watching videotapes in which the individual's reputation and helpful behaviors were manipulated. Results indicated an interaction effect between reputation and helpful behaviors such that a helpful person with a good reputation received more rewards than did a helpful person with a bad reputation. In contrast, an unhelpful person with a good reputation did not receive better rewards than an unhelpful person with a bad reputation. Moreover, raters' liking of ratees and the motives raters attributed to ratees' helpful behaviors mediated the relationship between the manipulations and raters' reward decisions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feedback: A necessary condition for the goal setting-performance relationship.

Tested the prediction that feedback and goals would be interactively related to performance. This prediction complements the findings of Locke that knowledge alone is not a sufficient condition for effective performance. It was also hypothesized that feedback would facilitate the display of individual differences in goal setting and hence the goal setting–performance relationship. 38 undergraduates in a feedback group and 48 in a no-feedback group were evaluated on a number comparison task. Results support the hypotheses by indicating that (a) the individual differences in self-set goals were significantly higher in the feedback group than in the no-feedback group, and that (b) the relationship between goals and performance was significantly higher in the feedback condition than in the no-feedback condition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Meso-scale analysis of FRC using a two-step homogenization approach

This paper describes the development of a two-step homogenization approach for evaluating the elastic properties of fiber reinforced concrete (FRC). For that purpose, a finite element model of an FRC unit cell was generated. Prior to the generation of the unit cell finite element model, the interface transition zones (ITZ) and the aggregates were homogenized using an analytical approach. In the first step, the properties of a spherical aggregate and its concentric ITZ layer were homogenized via an analytical procedure. Then a numerical homogenization procedure was applied to the homogenized aggregate, the mortar, and the fibers to obtain the macroscopic properties of the FRC. The suggested framework executes the multi-scale analysis of FRC structures by incorporating an original concrete unit cell generator into a commercial finite element software package intended for simulating nonlinear solid mechanical problems. The results, obtained using the presented algorithm, are in very good agreement with experimental results.     

If it looks like a spammer and behaves like a spammer,it must be a spammer: analysis and detection of microblogging spam accounts

Spam in online social networks (OSNs) is a systemic problem that imposes a threat to these services in terms of undermining their value to advertisers and potential investors, as well as negatively affecting users’ engagement. As spammers continuously keep creating newer accounts and evasive techniques upon being caught, a deeper understanding of their spamming strategies is vital to the design of future social media defense mechanisms. In this work, we present a unique analysis of spam accounts in OSNs viewed through the lens of their behavioral characteristics. Our analysis includes over 100 million messages collected from Twitter over the course of 1 month. We show that there exist two behaviorally distinct categories of spammers and that they employ different spamming strategies. Then, we illustrate how users in these two categories demonstrate different individual properties as well as social interaction patterns. Finally, we analyze the detectability of spam accounts with respect to three categories of features, namely content attributes, social interactions, and profile properties.     

Unitary and non-unitary manipulations of qubit-bath entanglement: non-Markov qubit cooling

Initialization of quantum logic operations makes it imperative to cool down the information-carrying qubits as much and as fast as possible, so as to purify their state, or at least their ensemble average. Yet, the limit on the speed of existing cooling schemes is either the duration of the qubit equilibration with its bath or the decay time of an auxiliary state to one of the qubit states. Here we show that highly-frequent phase-shifts or measurements of the state of thermalized qubits can be designed to affect the qubit-bath entanglement so that the qubits undergo cooling, well before they re-equilibrate with the bath and without resorting to auxiliary states. These processes can be used in principally novel, advantageous, cooling schemes to assist quantum logic operations.     

Strain sensing of carbon fiber reinforced geopolymer concrete

Health monitoring of concrete structures is performed by assessing the structure’s state of stress. One such method involves monitoring electrical resistance variations as an indirect measure of stress variations. Carbon fibers were added to fresh geopolymer mix to enhance its electrical conductivity. AC-impedance spectroscopy analyses were performed on sample specimens to obtain their electrical resistance. Geopolymer concrete specimens entrained with carbon fibers were dynamically loaded in bending and uniaxial compression to observe changes in electrical resistance with respect to variations in their stress state. For beam specimens electrical resistance was found to follow a descending trend with increasing bending stresses. A more complex relationship was noted for cylinder specimens that were loaded axially. Overall experimental results suggest that conductive geopolymer could serve as a smart material in health monitoring applications of concrete structures.     

Modeling representative Gen‐IV molten fuel reactivity effects in the ZEPHYR ZPR ‐ LFR analysis

Studies related to severe core accidents constitute a crucial element in the safety design of Gen‐IV systems. A new experimental program, related to severe core accidents studies, is proposed for the zero‐power experimental physics reactor (ZEPHYR) future reactor. The innovative program aims at studying reactivity effects at high temperature during degradation of Gen‐IV cores by using critical facilities and surrogate models. The current study introduces the European lead‐cooled system (ELSY) as an additional Gen‐IV system into the representativity arsenal of the ZEPHYR, in addition to the sodium‐cooled fast reactors. Furthermore, this study constitutes yet another step towards the ultimate goal of studying severe core accidents on a full core scale. The representation of the various systems is enabled by optimizing the content of plutonium oxide in the ZEPHYR fuel assembly. The study focuses on representing reactivity variation from 900°C at nominal state to 3000°C at a degraded state in both ELSY and Advanced Sodium Technological Reactor for Industrial Demonstration (ASTRID) cores. The study utilizes the previously developed calculation scheme, which is based on the coupling of stochastic optimization process and Serpent 2 code for sensitivity analysis. Two covariance data are used: the ENDF 175 groups for ELSY and the Covariance Matrix Cadarache (COMAC) 33 groups for ASTRID. The effect of the energy group structure of the covariance data on the representativity process is found to be significant. The results for single degraded ELSY fuel assembly demonstrate high representativity factor (>0.95) for reactivity variation and for the criticality level. Also, it is shown that the finer energy group structure of the covariance matrices results in dramatic improvement in the representation level of reactivity variations.     

Full-scale field tests of concrete slabs subjected to blast loads

This paper describes full-scale field explosion tests on protected and unprotected concrete slabs. The experiments were performed by the Protective Technologies Research & Development Center of the Faculty of Engineering Sciences of the Ben-Gurion University of the Negev (BGU-PTR&DC) under a contract with the Israeli Ministry of Defense (MoD) and the supervision of the IDF Steering Committee for R&D of Protective Structures. The aims of the tests were to: (1) extract data on the dynamic response of an elementary concrete structure to blast loads in order to verify and validate (V&V) our corresponding computer codes; and (2) check the ability of aluminum foams to mitigate blast wave loads. Time-dependent measurements of the response of the concrete slabs to the blast wave loads were successfully recorded using a variety of measurement devices. The obtained data have been used to verify and validate our computer codes.     

Capacity and lattice strategies for canceling known interference

We consider the generalized dirty-paper channel Y=X+S+N,E{X/sup 2/}/spl les/P/sub X/, where N is not necessarily Gaussian, and the interference S is known causally or noncausally to the transmitter. We derive worst case capacity formulas and strategies for "strong" or arbitrarily varying interference. In the causal side information (SI) case, we develop a capacity formula based on minimum noise entropy strategies. We then show that strategies associated with entropy-constrained quantizers provide lower and upper bounds on the capacity. At high signal-to-noise ratio (SNR) conditions, i.e., if N is weak relative to the power constraint P/sub X/, these bounds coincide, the optimum strategies take the form of scalar lattice quantizers, and the capacity loss due to not having S at the receiver is shown to be exactly the "shaping gain" 1/2log(2/spl pi/e/12)/spl ap/ 0.254 bit. We extend the schemes to obtain achievable rates at any SNR and to noncausal SI, by incorporating minimum mean-squared error (MMSE) scaling, and by using k-dimensional lattices. For Gaussian N, the capacity loss of this scheme is upper-bounded by 1/2log2/spl pi/eG(/spl Lambda/), where G(/spl Lambda/) is the normalized second moment of the lattice. With a proper choice of lattice, the loss goes to zero as the dimension k goes to infinity, in agreement with the results of Costa. These results provide an information-theoretic framework for the study of common communication problems such as precoding for intersymbol interference (ISI) channels and broadcast channels.     

Approximate belief updating in max-2-connected Bayes networks is NP-hard

A max-2-connected Bayes network is one where there are at most 2 distinct directed paths between any two nodes. We show that even for this restricted topology, null-evidence belief updating is hard to approximate.