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21.
Conceptual modeling represents a domain independently of implementation considerations for purposes of understanding the problem at hand and communicating about it. However, different people may construct different models given the same domain. Variations among correct models, while known and familiar in practice, have hardly been investigated in the literature. Their roots are in the decisions made during the modeling process, where modelers face the need to map reality into modeling constructs. This paper reports an empirical study whose aim is to explore model variations and in particular to examine possible directions for reducing them. Specifically, the study uses a multimethod research paradigm to examine the effect of applying ontology-based modeling rules on modeling decisions as reflected in resulting model variations. The findings of the study provide insights into the variations phenomenon, as well as to the application of ontology-based modeling rules.  相似文献   
22.
We show an algorithm for bound consistency of global cardinality constraints, which runs in time O(n + n′) plus the time required to sort the assignment variables by range endpoints, where n is the number of assignment variables and n′ is the number of values in the union of their domains. It is the first efficient algorithm that achieves bound consistency for all variables, and not only the assignment variables.Partially supported by DFG grant SA 933/1-1.Partially supported by the EU IST Programme, IST-1999-14186 (ALCOM-FT).  相似文献   
23.
Requirements elicitation is the first activity in the requirements engineering process. It includes learning, surfacing, and discovering the requirements of the stakeholders of the developed system. Various elicitation techniques exist to help analysts elicit the requirements from the different stakeholders; the most commonly used technique is the interview. Analysts may have domain knowledge prior to the elicitation process. Such knowledge is commonly assumed to have positive effects on requirements engineering processes, in that it fosters communication, and a mutual understanding of the needs. However, to a minor extent, some negative effects have also been reported. This paper presents an empirical study in which the perceived and actual effects of prior domain knowledge on requirements elicitation via interviews were examined. The results indicate that domain knowledge affects elicitation via interview in two main aspects: communication with the customers and understanding their needs. The findings provide insights as to both the positive and negative effects of domain knowledge on requirements elicitation via interview, as perceived by participants with and without domain knowledge, and show the existence of an actual effect on the course of the interviews. Furthermore, these insights can be utilized in practice to support analysts in the elicitation process and to form requirements analysis teams. They highlight the different contributions that can be provided by analysts with different levels of domain knowledge in requirements analysis teams and the synergy that can be gained by forming heterogeneous teams of analysts.  相似文献   
24.
10 clinical psychologists applied a twelvefold category system of good and very good moments of client movement, progress, improvement, process, or change to 2 consecutive middle sessions of experiential psychotherapy. Findings show (1) a large proportion of good and very good moments in both sessions, (2) the distribution of these moments into a distinctive subset of the 12 categories, and (3) the occurrence of series and phases of good moments rather than discrete events. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
25.
Iterated Even–Mansour (EM) encryption schemes (also named “key-alternating ciphers”) were extensively studied in recent years as an abstraction of commonly used block ciphers. A large amount of previous works on iterated EM concentrated on security in an information-theoretic model. A central question studied in these papers is: What is the minimal number of rounds for which the resulting cipher is indistinguishable from an ideal cipher? In this paper, we study a similar question in the computational model: What is the minimal number of rounds, assuring that no attack can recover the secret key faster than trivial attacks (such as exhaustive search)? We study this question for the two natural key scheduling variants that were considered in most previous papers: the identical subkeys variant and the independent subkeys variant. In the identical subkeys variant, we improve the best known attack by an additional round and show that \(r=3\) rounds are insufficient for assuring security, by devising a key recovery attack whose running time is about \(n/\log (n)\) times faster than exhaustive search for an \(n\)-bit key. In the independent subkeys variant, we also extend the known results by one round and show that for \(r=2\), there exists a key recovery attack whose running time is faster than the benchmark meet-in-the-middle attack. Despite their generic nature, we show that the attacks can be applied to improve the best known attacks on several concrete ciphers, including the full \({\hbox {AES}^{2}}\) (proposed at Eurocrypt 2012) and reduced-round LED-128 (proposed at CHES 2012).  相似文献   
26.
There is some evidence suggesting that Ca2+ is involved in processes that occur during the development and function of spermatozoa. Calcium-dependent proteins, such as calmodulin, are expressed during mammalian spermatogenesis further suggesting that Ca2+ takes part in its regulation. However, the precise roles of Ca2+ in spermatogenesis remain to be elucidated. Calpains are a family of Ca(2+)-dependent cysteine proteases whose members are expressed ubiquitously or in a tissue-specific manner. Calpain has been demonstrated to mediate specific Ca(2+)-dependent processes including cell fusion, mitosis and meiosis. We herein followed the expression pattern of calpain's ubiquitous isoforms, 1 and 2, throughout spermatogenesis at the RNA and protein levels by RT-PCR and Western blotting analysis. Both RNA and protein studies revealed that these isoforms are expressed in all spermatogenic cells. The expression of calpain 1 levels is slightly higher in spermatocytes entering the meiotic phase. Both calpain isoforms are also expressed in mouse spermatozoa and are localized to the acrosomal cap. Inducing capacitated spermatozoa to undergo the acrosome reaction in the presence of a selective calpain inhibitor significantly reduced the acrosome reaction rate in a dose-dependent manner. Thus, calpain, a pluripotential protease with numerous substrates, may serve as an effector in more than one pathway in the complex process of spermatogenesis and in the events preceding fertilization, such as the acrosome reaction.  相似文献   
27.
This study investigated the impact of counseling groups as compared with educational groups on attitudes, levels of stress, and sense of control among parents of a child with learning disabilities (LD) and a non-LD sibling. Conducted in one learning center in Israel, the study comprised 49 families in the counseling group and 46 families in the educational group. Results of the hierarchical analyses (mixed models) indicated significantly higher gains in the counseling groups for both mothers (who participated in the intervention) and fathers (who did not), mostly with respect to the child with LD. Children's self-reports supported these gains. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
28.
Seminal advances in anticancer therapy as well as supportive care strategies have led to improved survival rates, posing an emphasis on preserving an optimum quality of life after cancer treatment. This recognition has paved the way to an increasing research of long-term side effects, both clinical and preclinical and to an ongoing design of a supportive care system to evaluate and treat long-term adverse effects of anticancer treatments, including the impact on fertility. As with many adverse effects induced by anticancer treatments, the literature comprised mostly clinical data with regard to chemotherapy-induced gonadotoxicity, while understanding of the biological mechanism is lagging. The impact of anticancer treatments on female fertility depends on the women's age at the time of treatment, the chemotherapy protocol, the duration, and total cumulative dose administered. Several suggested mechanisms that underlie chemotherapy-induced gonadotoxicity have been described. This review illustrates the clinical evidence, as well as its supportive preclinical studies, while proceeding from the 'bedside to the bench work' and provides an insight to what lies behind chemotherapy-induced gonadotoxicity.  相似文献   
29.
Sequence‐independent or “click” chemistry is applied for the preparation of a series of novel and structurally similar π‐conjugated oligomers. The new oligomers are prepared using Wittig–Horner chemistry from bifunctional building blocks that can be interconnected to one another at any desired sequence. The bifunctional building blocks consist of aromatic skeletons with acetal protected aldehyde groups on one side and a phosphonic acid diethyl ester group para to the aldehyde functionality. The first step in the arylenevinylene formation is a Wittig–Horner coupling of a functionalized aldehyde with the methyl phosphonate ester ylide of a bifunctional monomer. A stepwise protection–deprotection process is applied for the preparation of structurally similar π‐conjugated oligo‐phenylene vinylenes. New di‐, tri‐, penta‐, and hepta‐phenylenevinylenes are prepared and characterized. Selected penta‐arylenevinylenes are incorporated as the semiconductor channel in organic field‐effect transistors.  相似文献   
30.
Reports an error in the original article by S. Melamed et al (Journal of Applied Psychology, 1995[Feb], Vol 80[1], 29–42). The last two numerical entries in the Long-cycle RW vs. VW row in Table 3 were incorrect. The corrected table, which also includes a clarification to Footnote a, is presented. (The following abstract of this article originally appeared in record 1995-23399-001). The relation of objective work conditions (work underload, repetitive or varied work) and subjective monotony to job satisfaction, psychological distress, and sickness absence was examined in 1,278 male and female workers. Subjective monotony was moderately related to the objective work conditions. Hierarchical regression analyses showed that the effects on all outcomes were partially mediated by subjective monotony and were also directly related to repetitive work and work underload. Job satisfaction and psychological distress were mainly related to subjective monotony, whereas sickness absence was equally related to the work conditions and subjective monotony. The highest impact was observed for short-cycle repetitive work. Testing sex interactions revealed that sickness absence was related to the work conditions in women but not in men… (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
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