University of Memphis

About: University of Memphis is a education organization based out in Memphis, Tennessee, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 7710 authors who have published 20082 publications receiving 611618 citations. The organization is also known as: U of M.

Succession Planning in Family Business: The Impact of Owner Gender

Abstract: Research on succession planning in family businesses has largely neglected issues linked to owner gender. The present study examines the extent to which differences are evident between male- and female-led family businesses in succession planning processes. Using data from a national survey of family-business owners, we explore the predictors of the comprehensiveness of succession planning. The results confirm that there are similarities and differences between males and females in the determinants of succession planning.

Are Suicidal Behaviors Contagious in Adolescence? Using Longitudinal Data to Examine Suicide Suggestion

Abstract: Durkheim argued that strong social relationships protect individuals from suicide. We posit, however, that strong social relationships also have the potential to increase individuals’ vulnerability when they expose people to suicidality. Using three waves of data from the National Longitudinal Study of Adolescent Health, we evaluate whether new suicidal thoughts and attempts are in part responses to exposure to role models’ suicide attempts, specifically friends and family. We find that role models’ suicide attempts do in fact trigger new suicidal thoughts, and in some cases attempts, even after significant controls are introduced. Moreover, we find these effects fade with time, girls are more vulnerable to them than boys, and the relationship to the role model—for teenagers at least—matters. Friends appear to be more salient role models for both boys and girls. Our findings suggest that exposure to suicidal behaviors in significant others may teach individuals new ways to deal with emotional distress, na...

An index structure for efficient reverse nearest neighbor queries

Abstract: The Reverse Nearest Neighbor (RNN) problem is to find all points in a given data set whose nearest neighbor is a given query point. Just like the Nearest Neighbor (NN) queries, the RNN queries appear in many practical situations such as marketing and resource management. Thus, efficient methods for the RNN queries in databases are required. The paper introduces a new index structure, the Rdnn-tree, that answers both RNN and NN queries efficiently. A single index structure is employed for a dynamic database, in contrast to the use of multiple indexes in previous work. This leads to significant savings in dynamically maintaining the index structure. The Rdnn-tree outperforms existing methods in various aspects. Experiments on both synthetic and real world data show that our index structure outperforms previous methods by a significant margin (more than 90% in terms of number of leaf nodes accessed) in RNN queries. It also shows improvement in NN queries over standard techniques. Furthermore, performance in insertion and deletion is significantly enhanced by the ability to combine multiple queries (NN and RNN) in one traversal of the tree. These facts make our index structure extremely preferable in both static and dynamic cases.

Aftershock triggering by complete Coulomb stress changes

Abstract: [1] We examine the correlation between seismicity rate change following the 1992, M7.3, Landers, California, earthquake and characteristics of the complete Coulomb failure stress (CFS) changes (ΔCFS(t)) that this earthquake generated. At close distances the time-varying “dynamic” portion of the stress change depends on how the rupture develops temporally and spatially and arises from radiated seismic waves and from permanent coseismic fault displacement. The permanent “static” portion (ΔCFS) depends only on the final coseismic displacement. ΔCFS diminishes much more rapidly with distance than the transient, dynamic stress changes. A common interpretation of the strong correlation between ΔCFS and aftershocks is that load changes can advance or delay failure. Stress changes may also promote failure by physically altering properties of the fault or its environs. Because it is transient, ΔCFS(t) can alter the failure rate only by the latter means. We calculate both ΔCFS and the maximum positive value of ΔCFS(t) (peak ΔCFS(t)) using a reflectivity program. Input parameters are constrained by modeling Landers displacement seismograms. We quantify the correlation between maps of seismicity rate changes and maps of modeled ΔCFS and peak ΔCFS(t) and find agreement for both models. However, rupture directivity, which does not affect ΔCFS, creates larger peak ΔCFS(t) values northwest of the main shock. This asymmetry is also observed in seismicity rate changes but not in ΔCFS. This result implies that dynamic stress changes are as effective as static stress changes in triggering aftershocks and may trigger earthquakes long after the waves have passed.

Comparison of patterns of use, beliefs, and attitudes related to waterpipe between beginning and established smokers

Abstract: To compare patterns of use, beliefs, and attitudes related to waterpipe smoking between university students (beginning smokers) and cafe customers (established smokers) in Aleppo Syria, in order to explore the evolution of this smoking method. Two cross-sectional surveys were conducted among representative samples of university students (total 587, 48.4% men, mean age 22 years), and waterpipe users among cafe' customers (total 268, 60% men, mean age 30 years) in Aleppo, Syria. We used interviewer-administered questionnaire inquiring about pattern of waterpipe smoking (initiation, frequency), situational characteristics of use (partner, place, sharing), beliefs related to waterpipe smoking (harmful/addictive properties of waterpipe), attitudes related to waterpipe smoking (confidence in quitting, will to quit, motivation for quitting, past year quit attempt), and cigarette smoking. Daily and regular patterns of smoking become more prevalent with increased duration of smoking, but intermittent smoking remains the predominant pattern of waterpipe use. Women seem to be drawn later to the habit, which seem to escape the usual taboo against women's cigarette smoking. Patterns and context of waterpipe use tend to change with progress of the practice affecting frequency, setting, and sharing of waterpipe. Unlike beginners, established waterpipe smokers seem more smoking-method oriented, more hooked on the habit, less willing to quit, and less likely to foresee challenges to quitting. Use patterns and attitudes related to waterpipe smoking evolve to accommodate the change in dependence and life circumstances of the smoker. Most of use features, beliefs, attitudes, as well as time-course seem unique to this smoking method requiring novel approach to intervention.