Showing papers by "University of Haifa published in 1989"

Conceptual Bases of Arithmetic Errors: The Case of Decimal Fractions.

Abstract: This study examines children's efforts to make sense of new mathematics instruction. The study documents major categories of errors that appear consistently as children learn decimal fractions. It then establishes the conceptual sources of these errors. Whole number errors derive from children's applying rules for interpreting multidigit integers. Fraction errors derive from children's efforts to interpret decimals as fractions. Different curriculum sequences influence the probability that these classes of errors will appear. It is suggested that errors are a natural concomitant of students' attempts to integrate new material that they are taught with already established knowledge. Since errorful rules cannot be avoided in instruction, educators are encouraged to use them as useful diagnostic tools to detect the nature of children's understanding of a mathematics topic.

Single machine flow-time scheduling with a single breakdown

Abstract: We consider the problem of scheduling tasks on a single machine to minimize the flowtime. The machine is subject to breakdowns during the processing of the tasks. The breakdowns occur at a random times and the machine is unavailable until it is repaired. The times for repair are random and independent of each other and of the breakdown process. A task that is preempted due to a breakdown must be restarted and otherwise preemptions are not allowed. We show in the case of a single breakdown that if the distribution function of the time to breakdown is concave then Shortest Processing Time (SPT) first scheduling stochastically minimizes the flowtime. For the case of multiple breakdowns we show that SPT minimizes the expected flowtime when the times to breakdown are exponentially distributed. If the time for a single breakdown is known before scheduling begins, and the processing times of the tasks are also known, then we show that the problem of deciding whether there is a schedule with flowtime less than or equal to a given value is NP-complete. Finally, we bound the performance of SPT scheduling in the deterministic case when there is a single breakdown.

Genetic diversity of wild emmer wheat in Israel and Turkey : Structure, evolution, and application in breeding.

Abstract: Allozyme variation in the tetraploid wild emmer wheat, Triticum dicoccoides, the progenitor of all cultivated wheats, was studied for the proteins encoded by 42 gene loci in 1815 plants representing 37 populations - 33 from Israel and 4 from Turkey - sampled in 33 localities from 1979 to 1987. The results showed that: (a) 6 loci (14%) were monomorphic in all populations, 15 loci (36%) were locally polymorphic, and 21 loci (50%) were regionally polymorphic. These results are similar to those obtained earlier on 12 Israeli populations. All polymorphic loci (except 4) displayed high local levels of polymorphism (>/ 10%). (b) The mean number of alleles per locus, A, was 1.252 (range: 1.050–1.634); the proportion of polymorphic loci per population averaged 0.220 (range: 0.050–0.415); genic diversity, He, averaged 0.059 (range: 0.002–0.119). (c) Altogether there were 119 alleles at the 42 putative loci tested, 114 of these in Israel, (d) Genetic differentiation was primarily regional and local, not clinal; 70% of the variant alleles were common (>/ 10%) and not widespread, but rather localized or sporadic, displaying an “archipelago” population genetics and ecology structure. The coefficients of genetic distance between populations were high and averaged D = 0.134; range: 0.018–0.297, an indication of sharp genetic differentiation over short distances, (e) Discriminant analyses differentiated Israeli from Turkish populations, and within Israel, between central and 3 marginal regions, as well as between different soil-type populations, (f) Allozymic variation comprised 40% within and 60% between populations, (g) Gametic phase disequilibria were abundant, their number being positively correlated (rs = 0.60, P<0.01) with the humidity, (h) Multilocus organization was substantive, also positively correlated with humidity, (i) Allozyme diversity, overall and at single loci, was significantly correlated with, and partly predictable by, climatic and edaphic factors, (j) The distrubition of the significant positive and negative values and the absence of autocorrelations in the correlogram revealed no similar geographic patterns across loci, eliminating migration as a prime factor of population genetic differentiation. These results suggest: (I) during the evolutionary history of wild emmer, diversifying natural selection, through climatic and edaphic factors, was a major agent of genetic structure and differentiation at both the single and multilocus levels; (II) wild emmer harbors large amounts of genetic diversity exploitable as genetic markers in sampling and abundant genetic resources utilizable for wheat improvement.

The importance of being visible: On the role of attention in a mind viewed as an anarchic intelligence system i basic tenets

Abstract: This paper describes an attempt to view attention from the perspective of a pluralistic concept of information processing in the mind. The mind is likened to an anarchic intelligence system. It is assumed to comprise of a set of processing entities called modules that may be active in parellel. Their activation is externally driven, and their operation is not controlled by any other module. Cooperating among modules is often required for achieving goals. Cooperation calls for communication. Attention is assumed to regulate only the communication among modules. It exerts attentional emphasis by making the output of a to-be-attended module available for a maximal number of other modules, while limiting the ability of de-emphasised modules to disseminate their output. This is achieved by a mechanism called decoupling that controls the connections between modules. The control of decoupling that is required for attentional emphasis is associated with an aversive phenomenal aspect that is usually calle...

Social research on family lifestyles among Arabs in Israel.

Abstract: This analysis of the Arab family in Israel shows that the process of modernization among the Arabs in Israel is complex multidimensional and influenced by various forces which are at times contradictory. The Arab minority is affected not only by typical processes associated with modernization and westernization but also by its unique socio-political status in Israel and the dual problem of the competing national and citizenship identities. This complexity is reflected also in family life styles. One finds side by side both traditional and modern elements in family patterns. Kinship structure has been reorganized in an effective way and has become well integrated into the modern system. The hamula has become the main political unit in the local elections as well as the main unit in the marriage market. Nevertheless a considerable change has occurred in its economic role and identification with the hamula has declined strongly at the normative level. While a drastic change in the structure of the extended family has been noticed there has been some continuity in the extended relationships between family members. Despite the common elements of family life styles among the Arabs there is also a differentiation between the various groups: Moslems Druze Christians Bedouins and non-Bedouins. It is more appropriate to talk about family life styles among the Arabs in Israel rather than the Arab family in a general sense.

The two-factor model of self-reported mood: a cross-cultural replication.

Abstract: The cross-cultural stability of a two-factor model of self-reported mood was studied in Israel. Sixty women and 25 men filled out a 58-adjective Mood Check List, everyday for 45 consecutive days. Replicatory factor analyses demonstrated that the two-factor model of mood is applicable to both Israeli men and women and that this structure is consistent across American and Israeli cultures. Three implications of these findings are discussed. Replication of this structure in a diversified and unique culture, such as Israel, coupled with a previous replication in Japan (Watson, Clark, & Tellegen, 1984), is interpreted as lending considerable support to the assertion that this model of mood is cross-culturally consistent. Theoretical formulations and empirical findings derived and discovered in the U.S. can now be employed in planning and interpreting mood studies in Israel. The results of such studies can be incorporated within the general body of knowledge accumulating on this topic in the U.S.

Power, Capabilities, and Paradoxical Conflict Outcomes

Abstract: It has been persistently demonstrated that militarily superior states that are engaged in wars with militarily inferior ones may end up on the losing side. Unlike the processes by which military capabilities are converted into control over resources, the so-called “paradoxical conflict outcomes” phenomenon is more severe than a lack of correspondence between control over resources and control over outcomes. The paradox of power involves cases in which increased control over resources actually causes reduced control over outcomes. Several of the theoretical examples of this paradox are taken from social choice theory. These examples are applied to the analysis of the outcome of the Balkan Wars of 1912–1913 and of the Israeli invasion of Lebanon in 1982. The implications of the power paradox for theories of international politics are briefly discussed.

Burrow patterns of the mole rat Spalax ehrenbergi in two soil types (terra-rossa and rendzina) in Mount Carmel, Israel

Abstract: Complete burrow systems of the mole rat Spalax ehrenbergi (Rodentia; Spalacidae), from two sites on Mount Carmel in Israel, with different soil types (terra-rossa and rendzina), were excavated and described here for the first time. A comparison was made of burrow structure patterns in the two soils and of the sexes, with special attention to the features of the feeding tunnels. The pattern in the rendzina revealed longer burrows with a longer main tunnel and fewer branches per metre of the main tunnel, while the pattern in the terra-rossa revealed shorter burrows with a shorter main tunnel and a relatively higher number of branches. These differences can primarily be related to the different levels of food availability, which is higher in the terra-rossa. It is suggested that each of the patterns reflects the mole rat's ability to optimize foraging efficiency in accordance with its given food availability. The average total length of the males' burrows was much greater than those of the females' burrows in the rendzina soil. It appears that food requirements determine different burrow features of the sexes rather than reproduction requirements. Other tunnel features (e.g. structural complexity, depth and width, segment length and spatial arrangement) and the factors which may affect them, as well as burrow structure of young mole rats and evidence of the underground dispersion of young mole rats, were presented and discussed. Many similarities were found in a comparison of S. ehrenbergi burrow features with those of other solitary subterranean rodents.

Interaction between Examination Type, Anxiety State, and Academic Achievement in College Science; an Action-Oriented Research.

Abstract: The trait anxiety profile of future science teachers, as well as their preferences concerning types of examinations in science and mathematics, have been surveyed prior to the administration—within the various science courses—of several traditional and nontraditional types of examinations and the assessment of students' state anxieties as well as their respective performance, i.e., their academic achievements. Our major findings are that (a) Our students prefer by far examinations in which the emphasis is on understanding and analyzing rather than on knowing and “remembering,” that the use of any relevant material during the examinations be permitted, and that the time duration be practically unlimited (e.g., “take-home”–type examinations). (b) Students' state anxiety correlates with the type of the examination, with a tendency towards somewhat higher anxiety for females. The preferred types of examinations reduce test anxiety significantly, and result in higher grades accordingly. (c) The reduction of anxiety and the improvement in achievements as a function of the examination type are far more significant for low achievers compared with medium and high achievers. (d) Although teachers are aware of the student preferences, they persist in giving their students their own “pet”-type examinations. These results are discussed in terms of the implications for upgrading both science education and college student testing and assessment mechanisms.

The importance of being visible: On the role of attention in a mind viewed as an anarchic intelligence system: II. Application to the field of attention.

Abstract: The view of attention presented in the first part of this paper is elaborated and is shown to accommodate most known phenomena in selective, divided, and sustained attention. It is also used to discuss the major issues in the domain of attention. The present approach to these issues is compared with other approaches. Finally, the stance of the present view with regard to the mind-body issue is discussed.

Semi-automated radiotherapy treatment planning with a mathematical model to satisfy treatment goals.

Abstract: Iterative algorithms can provide a feasible solution, if any exists, to specified treatment goals. Our model subdivides both the patient's cross section into a fine grid of points and the radiation beam into a set of “pencil” rays. The anatomy, treatment machine parameters, dose limits and homogeneity, are all defined. This process of subdivision leads to a large system of linear inequalities with a solution that provides a radiation intensity distribution that will deliver a prescribed dose distribution. The clinical results from two different algorithms will be presented and contrasted. Once the anatomy, treatment, and machine parameters have been entered, the computerized algorithms yield an answer in several minutes. The Cimmino algorithm also allows “weights” or priority assignments of the treatment goals. The resulting solution is biased towards fulfilling the specified doses for the anatomic regions which were given greater weight. It is desirable to have a systematic search of possible treatment alternatives in complex clinical situations, including 3-dimensional radiation therapy treatment planning (RTTP). Our method has been applied to 2-D RTTP, but is equally applicable to 3-D RTTP with minor modifications.

Increasing empathy among medical students

Abstract: The objective of the research was to evaluate the short- and long-term effectiveness of teaching medical students interviewing skills. Methods of teaching communication skills included a workshop for clinical instructors, as an indirect approach, a workshop for medical students, as a direct approach, and a combination of both. Results demonstrated that in order to stimulate medical students to use supporting-interview skills, they themselves should participate in an interpersonal skills workshop. Being taught these skills by teachers who have participated in the workshop does not have the same positive effect.

Relationships of the chromosomal species in the Eurasian mole rats of the Spalax ehrenbergi group as determined by DNA-DNA hybridization, and an estimate of the spalacid-murid divergence time.

Abstract: DNA-DNA hybridization was used to measure the average genomic divergence among the four chromosomal species of the Eurasian mole rats belonging to theSpalax ehrenbergi complex (Rodentia: Spalacidae). The percent nucleotide substitutions in the single-copy nuclear DNA among the species ranged from 0 to 5%, suggesting that speciation has occurred with minor genomic changes in these animals. The youngest chromosomal species appear to differ by 0.2–0.6% base pair mismatch, which is only between one and three base differences in a 500-bp fragment. The interspecific values of percent nucleotide differences permit the recognition of two well-separated speciation events in theS. ehrenbergi complex, the older (of Lower Pleistocene age) having isolated the chromosomal species 2n=54 before the divergence of the three other species. DNA-DNA hybridization was also used to compare the Spalacinae (Eurasian mole rats), Murinae (Old World rats and mice), and Arvicolinae (voles and lemmings). These data enabled us to estimate the time of divergence of the spalacids at ca. 19 million years ago. The dates of divergence among the other rodent lineages, as predicted by DNA hybridization results, agree well with paleontological data. These dates of divergence are obtained by the relation between geological time and single-copy nuclear DNA change, a relation that was calibrated by Catzeflis et al. (1987) through the use of fossil Arvicolinae and Murinae data.

Volatiles of two chemotypes of Majorana syriaca L. (Labiatae) as olfactory cues for the honeybee.

Abstract: A study of olfactory discrimination by honeybee has been set up in order to understand the role of volatiles of the aromatic plant Majorana syriaca in attracting pollinating insects. The honeybee's response to volatiles from leaves and inflorescences of two M. syriaca chemotypes, which differ in the thymol carvacrol ratio of their volatiles, was tested using a bioessay method based on associative conditioning and recruitement techniques. Behavioural data show that a honeybee identifies and reacts selectively to olfactory signals from leaves and from inflorescences of the two chemotypes. Such data suggest that the volatiles from all parts of the aromatic plant M. syriaca may have a role in attracting pollinators. The vegetative parts produce a volatile emission which attracts the pollinators from a distance towards the whole plant. At close range these are directed by the flower signal which is amplified by the volatiles of bracts and leaves in the inflorescence.

Adolescents' ability to communicate spatial information: Analyzing and effecting students' performance

Abstract: This study presents evidence which suggests that even though students in grades 6 through 8 are familiar with a variety of types of representation modes, they have great difficulty in successfully communicating spatial information. A Building Description Task, which consists ofa building made up of ten small cubes taped together and a set of instructions, was presented to a sample of middle school children. They were asked to “help your friend to know what your building looks like.” Students' attempts were classified by representation mode (verbal, mixed, graphic) and analyzed by grade and by sex. In addition, the effect of instruction in spatial visualization activities on students' preference for representation mode and rate of success on the task was assessed. The findings were examined relative to the practical teaching implications, to individual differences in spatial visualization ability and to design of spatial tests.

The effect of school entrance age on academic achievement and social‐emotional adjustment of children: Follow‐up study of fourth graders

Abstract: One hundred and thirty-seven fourth-grade pupils participated in a follow-up study of the effect of school-entrance age on academic achievement and social-emotional functioning. The sample included 73 oldest pupils, born in the months of January to March, and 64 youngest pupils, born in October to December of the same calendar year. Results indicated that differences between the two groups in academic and social-emotional measures, found when the subjects were in first grade, persisted in part to the fourth grade. The youngest subjects continued to score lowest in mathematics and in oral and silent reading comprehension; they were slower readers; and they had higher trait anxiety scores. In addition, the differences between the groups in oral and silent reading comprehension performance were found to increase over the years.

Sex, ethnic, and social differences in test anxiety among Israeli adolescents.

Abstract: The effects of sex, ethnicity, and social class on levels of test anxiety were examined among a sample of 416 adolescent students in Israel. Significant sex differences in mean levels of test anxiety were found, with girls scoring consistently higher than boys across ethnic, social, and grade categories. Pupils of low socioeconomic status (SES) also scored consistently higher than pupils of high SES across grades. Nevertheless, this study provides little support for the commonly held view that sociocultural or sex group differences in school achievement are due, in any meaningful way, to differences in test anxiety. The group differences, though significant for SES and sex, were of negligible magnitude, and the correlation between test anxiety scores and grade point average was minimal for the group as a whole and nonsignificant for students of Eastern background, who have been purported to be particularly affected by high levels of test anxiety. The findings do support other cross-cultural studies, which have found only a modicum of shared variance between test anxiety and grades. It is concluded that test anxiety is not a particularly valid predictor of achievement or ability.

Non‐financial employment commitment: A cross‐national comparison*

Abstract: The so-called ‘lottery question’, asking, ‘Would you stop or continue working if there were no economic reasons to carry on working?’ was utilized to evaluate non-financial employment commitment. Results of a representative sample of the labour force in seven countries (n = 8763) showed that between 68.8 per cent (in Great Britain) and 93.4 per cent (in Japan) of the workers indicated a desire to continue working.

Why is word recognition impaired by disorientation while the identification of single letters is not

Abstract: Past research has shown that speed of identifying single letters or digits is largely indifferent to orientation, whereas the recognition of single words or connected text is markedly disrupted by disorientation. In a series of four experiments, we attempted to reconcile these findings. The results suggest that disorientation does not impair the identification of the characters but disrupts the perception of their spatial arrangement. When spatial order information is critical for distinguishing between different stimuli, disorientation is disruptive because some rectification process is required to restore order information. Utilizing the similarity between the letter B and the number 13, we found strong effects of orientation when a stimulus was interpreted as the two-digit number 13 but not when interpreted as the single letter B. This, however, occurred only when the set of numbers to be classified included permutations of the same digits (Experiments 1 and 2). Odd-even decisions on single-digit and two-digit numbers (Experiment 3) yielded strong effects of stimulus orientation for order-dependent numbers (e.g., 32), weaker effects for order-independent numbers (e.g., 24), and none for repeated-digit (e.g., 22) or single-digit numbers. Classification time for two-letter Hebrew words evidenced strong effects of orientation for words that differed only in letter order but much weaker effects for words that had no letters in common, even when these were embedded within some words that did (Experiment 4). Language: en

Foraging strategy in a subterranean rodent, Spalax ehrenbergi: a test case for optimal foraging theory.

Abstract: The foraging behavior of the subterranean mole rat Spalax ehrenbergi (Rodentia, Spalacidae) was tested according to the framework of optimal foraging theory. We compared the frequencies of food species hoarded in storage chambers of mole rats with the frequencies of these species occurring in the vicinity of the mole rats' nest mounds during the winter and spring seasons. In addition, we examined the food composition of several summer nest mounds. Laboratory observations were conducted in order to test the foraging behavior of mole rats under simulated subterranean conditions. The mole rat is a generalist and collects a variety of food species. Out of 33 plant species that were hoarded by mole rats in the 21 studied nest mounds, 61% (n=20) were geophytes, 21% (n=7) perennial herbs, 15% (n=5) annual herbs and 3% (n=1) dwarf shrubs. The frequency of each collected species in the 16 winter and spring nest mounds is in general accordance with its frequency in the mole rat's territory. This implies that the mole rat randomly samples the food reserve of its territory without special preference or directed search for a particular species. The collection or avoidance of any food item is not dependent on the presence or absence of any other food item. We suggest that the foragin generalism of the mole rat is a product of the constraints of a subterranean niche - the necessity to hoard food as much as possible in a limited time period and the high energetic investment of tunneling to the food items.

Islamic medical ethics in the 20th century.

Abstract: While the practice of Western medicine is known today to doctors of all ethnic and religious groups, its standards are subject to the availability of resources. The medical ethics guiding each doctor is influenced by his/her religious or cultural background or affiliation, and that is where diversity exists. Much has been written about Jewish and Christian medical ethics. Islamic medical ethics has never been discussed as an independent field of ethics, although several selected topics, especially those concerning sexuality, birth control and abortions, have been more discussed than others. Islamic medical ethics in the 20th century will be characterised on the basis of Egyptian fatawa (legal opinions) issued by famous Muslim scholars and several doctors. Some of the issues discussed by Islamic medical ethics are universal: abortions, organ transplants, artificial insemination, cosmetic surgery, doctor-patient relations, etc. Other issues are typically Islamic, such as impediments to fasting in Ramadan, diseases and physical conditions that cause infringement of the state of purity, medicines containing alcohol, etc. Muslims' attitudes to both types of ethical issues often prove that pragmatism prevails and the aim is to seek a compromise between Islamic heritage and the achievements of modern medicine, as long as basic Islamic dogma is not violated.

On combining approval with disapproval voting

Abstract: In this paper we compare two nonranked voting methods: regular approval voting (RAV) and combined approval voting (CAV). Under RAV a voter has two options with respect to each of the competing alternatives—cast one vote in favor or abstain, whereas under CAV he has three options—cast one vote in favor, abstain, or cast one vote against. Under both voting methods it is assumed that one must elect one out of three or more competing alternatives and that the alternative obtaining the largest (net) number of votes is elected. The comparison between these two voting methods shows: 1. Given that a voter is in a decisive position, he will prefer to operate under CAV than under RAV. No voter under CAV will choose to abstain with respect to any of the alternatives. 2. If all voters employ their dominant strategies the final outcome under both voting systems will be the same. 3. For any number of voters and competing alternatives, a single (nth) voter has a smaller probability of not being decisive under RAV and a larger probability of being strongly decisive under CAV. Consequently, the choice between RAV and CAV should depend on: (i) the magnitude of the difference between the expected utility a voter enjoys when he is strongly decisive and the expected disutility he suffers when he is not decisive; (ii) whether, ceteris paribus, a voter derives any psychological satisfaction from being able to vote against disapproved alternatives (CAV) instead of merely abstaining (RAV).

Agricultural location theory 1: basic models

Abstract: Agricultural location theory deals with both the location — allocation process of land uses by farmers, and the spatial organization of agricultural land uses. The major term in its classical versi...