$$(\alpha , \tau )$$-Monitoring for event detection in wireless sensor networks

Detecting abnormal events is one of the fundamental issues in wireless sensor networks (WSNs). In this paper, we investigate \((\alpha ,\tau )\)-monitoring in WSNs. For a given monitored threshold \(\alpha \), we prove that (i) the tight upper bound of \(\Pr [{S(t)} \ge \alpha ]\) is \(O\left( {\exp \left\{ { - n\ell \left( {\frac{\alpha }{{nsup}},\frac{{\mu (t)}}{{nsup}}} \right) } \right\} } \right) \), if \(\mu (t) < \alpha \); and (ii) the tight upper bound of \(\Pr [{S(t)} \le \alpha ]\) is \(O\left( {\exp \left\{ { - n\ell \left( {\frac{\alpha }{{nsup}},\frac{{\mu (t)}}{{nsup}}} \right) } \right\} } \right) \), if \(\mu (t) > \alpha \), where \(\Pr [X]\) is the probability of random event \(X,\, S(t)\) is the sum of the monitored area at time \(t,\, n\) is the number of the sensor nodes, \(sup\) is the upper bound of sensed data, \( \mu (t)\) is the expectation of \(S(t)\), and \(\ell ({x_1},{x_2}) = {x_1}\ln \left( {\frac{{{x_1}}}{{{x_2}}}} \right) + (1 - {x_1})\ln \left( {\frac{{1 - {x_1}}}{{1 - {x_2}}}} \right) \). An instant \((\alpha ,\tau )\)-monitoring scheme is then developed based on the upper bound. Moreover, approximate continuous \((\alpha , \tau )\)-monitoring is investigated. We prove that the probability of false negative alarm is \(\delta \), if the sample size is Open image in new window for a given precision requirement, where Open image in new window is the Open image in new window fractile of a standard normal distribution. Finally, the performance of the proposed algorithms is validated through experiments.     

A manually-checkable proof for the NP-hardness of 11-color pattern self-assembly tileset synthesis

Patterned self-assembly tile set synthesis (pats) aims at minimizing the number of distinct DNA tile types used to self-assemble a given rectangular color pattern. For an integer k, k-pats is the subproblem of pats that restricts input patterns to those with at most k colors. We give an efficient Open image in new window verifier, and based on that, we establish a manually-checkable proof for the NP-hardness of 11-pats; the best previous manually-checkable proof is for 29-pats.     

A simple approach to an integrated single-vendor single-buyer inventory system with shortage

In this article, a simple approach with two basic inequalities (Cauchy–Schwarz inequality and arithmetic–geometric mean inequality) is used to solve the integrated single-vendor single-buyer inventory problem developed by Wu and Ouyang (Wu, K.-S. and Ouyang, L.-Y., 2003. An integrated single-vendor single-buyer inventory system with shortage derived algebraically. Production Planning & Control, 14 (6), 555–561). Without the method of completing perfect square, the proposed approach yields the global minimum of the integrated total cost per year more easily than the algebraic approach used by Wu and Ouyang (2003 Wu, K-S and Ouyang, L-Y. 2003. An integrated single-vendor single-buyer inventory system with shortage derived algebraically. Production Planning & Control, 14(6): 555–561. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]). In addition, for people without the background of calculus, it is more useful to determine the buyer's economic order quantity and the vendor's optimal number of deliveries.     

When stressors make you work: Mechanisms linking challenge stressors to performance

Based on previous empirical findings, “challenge stressors” (Cavanaugh, Boswell, Roehling, & Bouderau, 2000 Cavanaugh, M. A., Boswell, W. R., Roehling, M. V., & Boudreau, J. W. (2000). An empirical examination of self-reported work stress among U.S. managers. Journal of Applied Psychology, 85, 65–74. doi:10.1037/0021-9010.85.1.65[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Lepine, Podsakoff, & Lepine, 2005 LePine, J. A., Podsakoff, N. P., & LePine, M. A. (2005). A meta-analytic test of the challenge stressor hindrance stressor framework: An explanation for inconsistent relationships among stressors and performance. Academy of Management Journal, 48, 764–775. doi: 10.5465/AMJ.2005.18803921[Crossref], [Web of Science ®] , [Google Scholar]), such as the amount and scope of responsibility, can be loosely considered as “good stressors” that are consistently and positively related to job satisfaction and performance. We introduce the role of appraisal to further examine how challenge stressors are connected to performance. Structural equation modelling analyses using an applied sample of 284 employee–supervisor dyads showed that affective commitment to the organization mediated the relationship between both opportunity and threat appraisal and performance (in-role and extra-role). The mediating role of increased psychosomatic distress was supported only for the relationship between threat appraisal and in-role performance. The findings indicate the importance of taking into account the actual appraisal of “challenge stressors”, as it carries implications for performance, and reveals the key role of affective commitment and induced distress mechanisms in this relationship. In conclusion, “challenge stressors” are not always positively related to performance, but only when they are perceived as opportunities.     

Special Issue for FAW 2014

For a graph \(G=(V,E)\), a dominating set is a set \(D\subseteq V\) such that every vertex \(v\in V\setminus D\) has a neighbor in \(D\). The minimum outer-connected dominating set (Min-Outer-Connected-Dom-Set) problem for a graph \(G\) is to find a dominating set \(D\) of \(G\) such that \(G[V\setminus D]\), the induced subgraph by \(G\) on \(V\setminus D\), is connected and the cardinality of \(D\) is minimized. In this paper, we consider the complexity of the Min-Outer-Connected-Dom-Set problem. In particular, we show that the decision version of the Min-Outer-Connected-Dom-Set problem is NP-complete for split graphs, a well known subclass of chordal graphs. We also consider the approximability of the Min-Outer-Connected-Dom-Set problem. We show that the Min-Outer-Connected-Dom-Set problem cannot be approximated within a factor of \((1-\varepsilon ) \ln |V|\) for any \(\varepsilon >0\), unless NP \(\subseteq \) DTIME(\(|V|^{\log \log |V|}\)). For sufficiently large values of \(\varDelta \), we show that for graphs with maximum degree \(\varDelta \), the Min-Outer-Connected-Dom-Set problem cannot be approximated within a factor of \(\ln \varDelta -C \ln \ln \varDelta \) for some constant \(C\), unless P \(=\) NP. On the positive side, we present a \(\ln (\varDelta +1)+1\)-factor approximation algorithm for the Min-Outer-Connected-Dom-Set problem for general graphs. We show that the Min-Outer-Connected-Dom-Set problem is APX-complete for graphs of maximum degree 4.     

Reverse exchange of healthcare devices: the case of hearing aid equipment in the UK

Abstract

Reverse exchange (RE) in dealing with the return, recycle and reuse of products is receiving a growing focus. When properly handled, RE in healthcare can deliver an economic benefit of cost minimisation and has extensive positive impacts on both human health and the environment (Li and Olorunniwo 2008 Li, X., and F. Olorunniwo. 2008. “An Exploration of Reverse Logistics Practices in Three Companies.” Supply Chain Management: An International Journal 13 (5): 381–386. doi:10.1108/13598540810894979[Crossref], [Web of Science ®] , [Google Scholar]) but to date, RE research is mostly limited to pharmaceutical return. This paper investigates the potential for RE benefits in the UK National Health Service (NHS) supply chain for medical devices. Hearing aids supplied to adults with hearing loss are used as an illustrative example. This research applied a consensus approach through the use of dispersed nominal groups in order to obtain qualitative data on information, barriers, solutions and priorities to support findings. Findings illustrate that the end user behaviour of returning the device, and the requirement by NHS Procurement for manufacturers to meet RE targets are secondary to the importance of audiology departments who have the autonomy to design RE processes and successfully implement initiatives. A schematic highlighting the information and materials flow of the supply chain and the barriers and facilitators to RE is presented for hearing aid devices with potential for transferability to other small medical device supply chains.     

Disjunctive total domination in graphs

Let \(G\) be a graph with no isolated vertex. In this paper, we study a parameter that is a relaxation of arguably the most important domination parameter, namely the total domination number, \(\gamma _t(G)\). A set \(S\) of vertices in \(G\) is a disjunctive total dominating set of \(G\) if every vertex is adjacent to a vertex of \(S\) or has at least two vertices in \(S\) at distance \(2\) from it. The disjunctive total domination number, \(\gamma ^d_t(G)\), is the minimum cardinality of such a set. We observe that \(\gamma ^d_t(G) \le \gamma _t(G)\). We prove that if \(G\) is a connected graph of order \(n \ge 8\), then \(\gamma ^d_t(G) \le 2(n-1)/3\) and we characterize the extremal graphs. It is known that if \(G\) is a connected claw-free graph of order \(n\), then \(\gamma _t(G) \le 2n/3\) and this upper bound is tight for arbitrarily large \(n\). We show this upper bound can be improved significantly for the disjunctive total domination number. We show that if \(G\) is a connected claw-free graph of order \(n > 14\), then \(\gamma ^d_t(G) \le 4n/7\) and we characterize the graphs achieving equality in this bound.     

F_{3}-domination problem of graphs

Given a graph \(G\) and a set \(S\subseteq V(G),\) a vertex \(v\) is said to be \(F_{3}\) -dominated by a vertex \(w\) in \(S\) if either \(v=w,\) or \(v\notin S\) and there exists a vertex \(u\) in \(V(G)-S\) such that \(P:wuv\) is a path in \(G\) . A set \(S\subseteq V(G)\) is an \(F_{3}\) -dominating set of \(G\) if every vertex \(v\) is \(F_{3}\) -dominated by a vertex \(w\) in \(S.\) The \(F_{3}\) -domination number of \(G\) , denoted by \(\gamma _{F_{3}}(G)\) , is the minimum cardinality of an \(F_{3}\) -dominating set of \(G\) . In this paper, we study the \(F_{3}\) -domination of Cartesian product of graphs, and give formulas to compute the \(F_{3}\) -domination number of \(P_{m}\times P_{n}\) and \(P_{m}\times C_{n}\) for special \(m,n.\)      

5 Bringing National Culture to the Table: Making a Difference with Cross‐cultural Differences and Perspectives

Abstract

Cross‐cultural research has achieved a front‐and‐center role in management and social psychology. In this chapter, we attempt to address the fundamental issue of what makes cross‐cultural research valuable. In doing so, we first summarize major methodological and conceptual themes across recent reviews. We then raise the question about the criticality of cross‐cultural differences, i.e., whether cross‐cultural differences are required for research in this domain to matter. Most efforts exerted by cross‐cultural researchers have been directed toward uncovering and explaining cross‐cultural differences, or finding better ways to do so. However, differences per se do not necessarily make an important difference in advancing knowledge. Instead, we argue that a more fundamental value of cross‐cultural research is the diverse perspectives it offers for theoretical innovation. Using Wagner and Berger’s (1985 Wagner, D.G. and Berger, J. 1985. Do sociological theories grow?. American Journal of Sociology, 90: 697–728. [Crossref], [Web of Science ®] , [Google Scholar]) typology, we examine how the inclusion of “other cultural” perspectives has contributed to knowledge growth in social psychology and organizational behavior. We conclude with suggestions for how the field can further realize the inherent benefits of diverse cultural perspectives in future research.     

Evaluating Behavioral Self-Monitoring With Accuracy Training for Changing Computer Work Postures

The primary purpose of this study was to replicate and extend a study by Gravina, Austin, Schroedter, and Loewy (2008) Gravina, N., Austin, J, Schroedter, L. and Loewy, S. 2008. The effects of self-monitoring on safe postural performance. Journal of Organizational Behavior Management, 28: 238–259. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]. A similar self-monitoring procedure, with the addition of self-monitoring accuracy training, was implemented to increase the percentage of observations in which participants worked in neutral postures. The accuracy training required the three participants to practice self-monitoring with the experimenter at least 20 times and to meet the criteria of 90% accuracy for the last 10 monitors. Feedback was delivered after each monitor. Two postures for each of the three participants were targeted by the intervention, and all six improved with an average effect size of 4.7 (range: 3.4 to 8.2) compared to Gravina et al., in which effect sizes averaged 1.9 (range:??.1 to 3.2). In addition, participant self-monitoring was more accurate overall (77%) when compared to Gravina et al. (44%).     

Lower bounds for independence numbers of some locally sparse graphs

An \(m\) -distinct-coloring is a proper vertex-coloring \(c\) of a graph \(G\) if for each vertex \(v\in V\) , any color appears in at most one of \(N_0(v)\) , \(N_1(v)\) , \(\ldots \) , and \(N_m(v)\) , where \(N_i(v)\) is the set of vertices at distance \(i\) from \(v\) . In this note, we show that if \(G\) is \(C_{2m+1}\) -free which is assigned an \((m+1)\) -distinct-coloring \(c\) , then \(\alpha (G)c(G)^{1/m}\ge \Omega \Big (\sum _{v} c(v)^{1/m}\Big )\) , where \(c(G)\) is the number of colors used in \(c\) and \(c(v)\) is the number of different colors appearing in \(N_1(v)\) . Moreover, we obtain that if \(G\) has \(N\) vertices and it contains neither \(C_{2m+1}\) nor \(C_{2m}\) , then \(\alpha (G)\ge \Omega \big ((N\log N)^{m/(m+1)}\big )\) . The algorithm in the proof for the first result is random, and that for the second is constructive.     

Building better measures of role ambiguity and role conflict: The validation of new role stressor scales

Occupational stress researchers have given considerable attention to role ambiguity and role conflict as predictors of employee health, job attitudes and behaviour. However, the validity of the Rizzo, House, and Lirtzman’s (1970 Rizzo, J. R., House, R. J., &; Lirtzman, S. I. (1970). Role conflict and ambiguity in complex organizations. Administrative Science Quarterly, 15, 150–163. doi: 10.2307/2391486[Crossref], [Web of Science ®] , [Google Scholar]) scales – the most popular role stressor measures – has been a source of disagreement among researchers. In response to the disputed validity of the Rizzo et al. scales, we developed new measures of role ambiguity and role conflict and conducted five studies to examine their psychometric qualities (Study 1 N?=?101 U.S. workers; Study 2 N?=?118 workers primarily employed in the U.S.; Study 3 N?=?135 employed U.S. MBA students; Study 4 N?=?973 members of the U.S. Air Force (USAF); Study 5 N?=?234 workers primarily employed in the U.S.). Across these five studies, we found that the new role stressor scales have desirable psychometric qualities: they displayed high levels of substantive validity, high levels of internal consistency and test–retest reliability, they produced an interpretable factor structure, and we found evidence of their construct validity. We therefore recommend that these new scales be used in future research on role stress.     

A temporal investigation of the direct,interactive, and reverse relations between demand and control and affective strain

Abstract

Few studies have tested how stressors affect outcomes over time. We sought to extend the literature by means of a longitudinal study testing for direct, interactive, and causal relations between demands and control and affective strain. We extended prior work testing causal relationships for Karasek's (1979 Karasek, R.A. Jr. 1979. Job demands, job decision latitude, and mental strain: Implications for job redesign. Administrative Science Quarterly, 24: 285–307. [Crossref], [Web of Science ®] , [Google Scholar]) Job Demand-Control (JDC) model by examining both the effects of demands and control on strain and in turn the effects of strain on demand and control. We tested our hypotheses using hierarchical linear modelling with a military sample of 1539 soldiers who completed six waves of survey data at 3-month time lags. The results replicate earlier cross-sectional studies reporting effects of work characteristics on strain; however, in our study these effects did not persist past three months. The results also provide evidence for reverse causal effects such that higher strain was associated with higher subsequent work overload and lower control over a six month time period. Similar to past research, we did not find support for the interactive effects of work overload and control on strain. We discuss the implications of our findings for theory and practice (such as the optimum time for applying interventions during the management of change), especially in terms of understanding the specific time lags for different stress–strain associations and the need for additional theories to explain reverse relationships.     

Further Evaluation of the Accuracy of Managerial Prediction of Employee Preference

Previous research (i.e., Wilder, Rost, &; McMahon, 2007 Wilder, D. A., Rost, K. and McMahon, M. 2007. The accuracy of managerial prediction of employee preference: A brief report. Journal of Organizational Behavior Management, 27(2): 1–14. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) has suggested that managers perform poorly when predicting items and activities which their employees state that they might like to earn as part of performance improvement programs. The purpose of the current study was to replicate the earlier study conducted by Wilder et al. (2007 Wilder, D. A., Rost, K. and McMahon, M. 2007. The accuracy of managerial prediction of employee preference: A brief report. Journal of Organizational Behavior Management, 27(2): 1–14. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) with a larger and more diverse sample of managers and employees. One hundred employees and 15 managers were asked to rank order a list of items/activities they thought their employees would most prefer to be incorporated into a performance improvement plan. Next, employee preference for these same items was directly assessed using an employee reinforcer survey. Kendall rank-order correlation coefficients were used to compare the results of the managerial rank with the employee reinforcer survey. Correlations ranged from ?.6 to 1, with a mean of .25.     

Distance-d independent set problems for bipartite and chordal graphs

The paper studies a generalization of the Independent Set problem (IS for short). A distance- $d$ independent set for an integer $d\ge 2$ in an unweighted graph $G = (V, E)$ is a subset $S\subseteq V$ of vertices such that for any pair of vertices $u, v \in S$ , the distance between $u$ and $v$ is at least $d$ in $G$ . Given an unweighted graph $G$ and a positive integer $k$ , the Distance- $d$ Independent Set problem (D $d$ IS for short) is to decide whether $G$ contains a distance- $d$ independent set $S$ such that $|S| \ge k$ . D2IS is identical to the original IS. Thus D2IS is $\mathcal{NP}$ -complete even for planar graphs, but it is in $\mathcal{P}$ for bipartite graphs and chordal graphs. In this paper we investigate the computational complexity of D $d$ IS, its maximization version MaxD $d$ IS, and its parameterized version ParaD $d$ IS( $k$ ), where the parameter is the size of the distance- $d$ independent set: (1) We first prove that for any $\varepsilon >0$ and any fixed integer $d\ge 3$ , it is $\mathcal{NP}$ -hard to approximate MaxD $d$ IS to within a factor of $n^{1/2-\varepsilon }$ for bipartite graphs of $n$ vertices, and for any fixed integer $d\ge 3$ , ParaD $d$ IS( $k$ ) is $\mathcal{W}[1]$ -hard for bipartite graphs. Then, (2) we prove that for every fixed integer $d\ge 3$ , D $d$ IS remains $\mathcal{NP}$ -complete even for planar bipartite graphs of maximum degree three. Furthermore, (3) we show that if the input graph is restricted to chordal graphs, then D $d$ IS can be solved in polynomial time for any even $d\ge 2$ , whereas D $d$ IS is $\mathcal{NP}$ -complete for any odd $d\ge 3$ . Also, we show the hardness of approximation of MaxD $d$ IS and the $\mathcal{W}[1]$ -hardness of ParaD $d$ IS( $k$ ) on chordal graphs for any odd $d\ge 3$ .     

2-Rainbow domination number of Cartesian products: C_{n}\square C_{3} and C_{n}\square C_{5}

A function \(f:V(G)\rightarrow \mathcal P (\{1,\ldots ,k\})\) is called a \(k\) -rainbow dominating function of \(G\) (for short \(kRDF\) of \(G)\) if \( \bigcup \nolimits _{u\in N(v)}f(u)=\{1,\ldots ,k\},\) for each vertex \( v\in V(G)\) with \(f(v)=\varnothing .\) By \(w(f)\) we mean \(\sum _{v\in V(G)}\left|f(v)\right|\) and we call it the weight of \(f\) in \(G.\) The minimum weight of a \( kRDF\) of \(G\) is called the \(k\) -rainbow domination number of \(G\) and it is denoted by \(\gamma _{rk}(G).\) We investigate the \(2\) -rainbow domination number of Cartesian products of cycles. We give the exact value of the \(2\) -rainbow domination number of \(C_{n}\square C_{3}\) and we give the estimation of this number with respect to \(C_{n}\square C_{5},\) \((n\ge 3).\) Additionally, for \(n=3,4,5,6,\) we show that \(\gamma _{r2}(C_{n}\square C_{5})=2n.\)      

Efficient algorithms for the max k -vertex cover problem

Given a graph  \(G(V,E)\) of order  \(n\) and a constant \(k \leqslant n\) , the max  \(k\) -vertex cover problem consists of determining  \(k\) vertices that cover the maximum number of edges in  \(G\) . In its (standard) parameterized version, max  \(k\) -vertex cover can be stated as follows: “given  \(G,\) \(k\) and parameter  \(\ell ,\) does  \(G\) contain  \(k\) vertices that cover at least  \(\ell \) edges?”. We first devise moderately exponential exact algorithms for max  \(k\) -vertex cover, with time-complexity exponential in  \(n\) but with polynomial space-complexity by developing a branch and reduce method based upon the measure-and-conquer technique. We then prove that, there exists an exact algorithm for max  \(k\) -vertex cover with complexity bounded above by the maximum among  \(c^k\) and  \(\gamma ^{\tau },\) for some \(\gamma < 2,\) where  \(\tau \) is the cardinality of a minimum vertex cover of  \(G\) (note that \({\textsc {max}}\,\) k \({\textsc {\!-vertex cover}}{} \notin \mathbf{FPT}\) with respect to parameter  \(k\) unless \(\mathbf{FPT} = \mathbf{W[1]}\) ), using polynomial space. We finally study approximation of max  \(k\) -vertex cover by moderately exponential algorithms. The general goal of the issue of moderately exponential approximation is to catch-up on polynomial inapproximability, by providing algorithms achieving, with worst-case running times importantly smaller than those needed for exact computation, approximation ratios unachievable in polynomial time.