Time filter

Source Type

Ben-Amram A.M.,The Academic College of Tel-Aviv-Yaffo
Logical Methods in Computer Science | Year: 2011

Size-Change Termination (SCT) is a method of proving program termination based on the impossibility of infinite descent. To this end we use a program abstraction in which transitions are described by monotonicity con-straints over (abstract) variables. When only constraints of the form x > y' and x ≥ y' are allowed, we have size-change graphs. In the last decade, both theory and practice have evolved significantly in this restricted framework. The crucial underlying assumption of most of the past work is that the domain of the variables is well-founded. In a recent paper I showed how to extend and adapt some theory from the domain of size-change graphs to general monotonicity constraints, thus complementing previous work, but remaining in the realm of well-founded domains. However, monotonicity constraints are, interestingly, capable of proving termination also in the integer domain, which is not well-founded. The purpose of this paper is to explore the application of monotonicity constraints in this domain. We lay the necessary theoretical foundation, and present precise decision procedures for termination; finally, we provide a procedure to construct explicit global ranking functions from monotonicity constraints in singlyexponential time, and of optimal worst-case size and dimension (ordinal). © A. M. Ben-Amram. Source

Einat H.,The Academic College of Tel-Aviv-Yaffo
Harvard Review of Psychiatry | Year: 2014

There is a well-known deficiency in valid animalmodels for bipolar disorder. Developing the single idealmodel for the disorder-one that will represent its full scope-will probably not be possible until we have a much better understanding of the underlying pathology. Yet, intermediatemodels, even with partial validity, are critical in order to advance our knowledge and put us into position to develop even better models. The present article discusses the various efforts under way to develop the best models based on our current level of understanding. These efforts include (1) identifying new tests, (2) developing models based on the endophenotypes approach, (3) identifying the best rodent strains, (4) identifying the most appropriate species, (5) segregating susceptible versus resilient animals, and (6) segregating animals that respond or do not respond to treatment. It is suggested that a combined approach that includes these directions and others can result in better models with higher validity that will offer significant help in advancing research on bipolar disorder and developing new and better treatments. © 2014 President and Fellows of Harvard College. Source

Ben-Amram A.M.,The Academic College of Tel-Aviv-Yaffo | Genaim S.,Complutense University of Madrid
Journal of the ACM | Year: 2014

In this article, we study the complexity of the problems: given a loop, described by linear constraints over a finite set of variables, is there a linear or lexicographical-linear ranking function for this loop? While existence of such functions implies termination, these problems are not equivalent to termination. When the variables range over the rationals (or reals), it is known that both problems are PTIME decidable. However, when they range over the integers, whether for single-path or multipath loops, the complexity has not yet been determined. We show that both problems are coNP-complete. However, we point out some special cases of importance of PTIME complexity. We also present complete algorithms for synthesizing linear and lexicographical-linear ranking functions, both for the general case and the special PTIME cases. Moreover, in the rational setting, our algorithm for synthesizing lexicographical-linear ranking functions extends existing ones, because our definition for such functions is more general, yet it has PTIME complexity. © 2014 ACM 0004-5411/2014/07-ART26 $15.00. Source

Braunstein-Bercovitz H.,The Academic College of Tel-Aviv-Yaffo
International Journal of Stress Management | Year: 2013

The purpose of the current study was to examine a theoretically-based multidimensional model, delineating the nature of the associations between perceived gain of three types of organizational resources and burnout, through the mediation of various dimensions of the work-family conflict (WFC). A sample of 179 mothers of young children, holding demanding careers (hospital nurses) completed several questionnaires. Consistent with the Conservation of Resources theory, structural equation modeling analysis (X2 = 9.24, df = 5, NFI = .93, CFI= .94, TLI = .90, and SRMR = .066) indicated that personal-empowerment (e.g., enhanced self-esteem and a sense of mastery and autonomy) and a supportive work-family culture at the workplace are negatively associated with burnout (β = .32, -.17). The relationship between personalempowerment and burnout was fully mediated by the strain-based source of both work interferes with family and family interferes with work dimensions of the conflict (β = -.18, -.15). These results imply that personal-empowerment may augment resiliency and general resistance to stressors, as it attenuates strain spillover from the work to the family domains, as well as from the family to the work domains. The relationship between a supportive work-family culture and burnout was fully mediated by the work interferes with family dimension (both strain- and time-based sources). However, reduced workload (in terms of sufficient time and space) was excluded from the final model, as it did not contribute to reduced WFC and burnout, above the contribution of the other resourcetypes. Implications for career planning and organizational change processes are discussed. © 2013 American Psychological Association. Source

Rymon D.,The Academic College of Tel-Aviv-Yaffo
Acta Horticulturae | Year: 2011

The recent global trend of increased demand for pomegranates, whether as fresh fruit or as derived products, is growing at an impressive pace. It is considered to be the outcome of the many favorable effects on human health these products were found to possess. The global published information on production and trade of pomegranates and the fruit's derivatives offers only an indistinct picture. This is due to the garden character of production in the leading producing countries (India, China and Iran). Often fruit is harvested from small, scattered plots with only a small number of trees. The fact that less than 10% of total production enters international trade exposes the industry to potential serious fluctuations: it is easy to significantly change the relative quantity entering trade by diverting even a small portion of production from domestic consumption to the international marketplace. The lecture presents the global distribution of the sources of supply. As a supplement, seasonal production is portrayed so that general supply is broken down by countries and months. Initially, we define the product "pomegranate" in those markets where the highest prices are obtained. The fruit is characterized by high variability, hence the definition is important. Cultivars, appearance, internal features (color, taste, softness of seeds, etc.) and other characteristics all cover a broad range. An important aspect of this market is the seasonal breakdown of the supply features, including prices determined, quantities supplied and their trends. In modern marketing the market favors brands and efficient positioning of a product. Among the famous brands in the pomegranate industry, the Californian line "POM Wonderful" - and the European juice "Pomegreat" are analyzed. It is of value to note - in addition to the fame, prices and reputation of these brands - the investment which has been needed to achieve their success stories. As an outcome of the previously presented characteristics of the market and the marketing of pomegranates and their derived products, an attempt is made to forecast the market situation for the coming years. The expectations are subjective and exposed to future general economic developments in both the western world, (North America, Europe and Japan) and the two giants - China and India. Source

Discover hidden collaborations