Showing papers by "Bar-Ilan University published in 1986"

Remittances and Inequality

Abstract: In this paper the authors propose a framework and develop techniques for analyzing the impact of migrant remittances on the distribution of rural income by size and subsequently its impact on rural welfare. Household data are used to assign numerical coefficients to the impact of net remittances from both internal and international migrants on income inequality in 2 Mexican villages. The impact of migrant remittances on the distribution of rural income by size depends critically on the degree to which migration opportunities become diffused through the village population on the returns to human capital embodied in remittances and on the distribution of potentially remittance-enhancing skills and education across village households. Our empirical findings demonstrate that in a village where many households contain internal migrants but few have experience migrating to the U.S. remittances from Mexico-to-US migrants have an unequalizing impact on village incomes while remittances from internal migrants have a favorable effect on the village income distribution. By contrast in a village with a long historyh of sending migrants to the US and hence a more ready access to US labor markets US-to-Mexico remittances have an equalizing impact on incomes. Remittances from internal migrants in this village however embody a large human capital component and are highly correlated with household income. Hence internal migrant remittances account for a comparatively large share of inequalities in the 2nd village. The overall effect of remittances on income inequality is favorable in both villages. Migration type migration stage and interaction terms all appear to play a role in this context. The effects of small changes in remittances upon income inequality and rural welfare in the 2 villages are explored and some implications for migration and rural development policy are considered. (authors modified)

Temporal association in asymmetric neural networks.

Abstract: A neural network model which is capable of recalling time sequences and cycles of patterns is introduced. In this model, some of the synaptic connections, ${J}_{\mathrm{ij}}$, between pairs of neurons are asymmetric (${J}_{\mathrm{ij}}\ensuremath{ e}{J}_{\mathrm{ji}}$) and have slow dynamic response. The effects of thermal noise on the generated sequences are discussed. Simulation results demonstrating the performance of the network are presented. The model may be also useful in understanding the generation of rhythmic patterns in biological motor systems.

Light Harvesting and Utilization by Phytoplankton

Abstract: Application d'un modele theorique a l'analyse des relations photosynthese-irradiance chez 3 especes marines phytoplanctoniques

Multinational Production: Effect on Brand Value

Abstract: Direct foreign investment in manufacturing abroad has a number of consequences for the firm. One aspect, particularly salient when the company's image is tied to its home country, is the impact of the DFI upon customer perceptions of the brand. The present study shows how changes in perceptions can be assessed prior to the investment decision, and how the brand value consequences of a particular location can be estimated. The proposed method is illustrated using data from a Japanese company's entry into the U.S.

Quantized Layer Growth at Liquid-Crystal Surfaces

Abstract: We report x-ray reflectivity measurements on the free surface of dodecylcyanobiphenyl (12CB) at the isotropic to smectic-A phase transition. At about 10?deC above ${\mathrm{T}}_{\mathrm{IA}}$, smectic-A-like ordering develops at the surface while the bulk phase remains isotropic. The angular dependence of the specular reflectivity is consistent with a sinusoidal density modulation, starting at the surface and terminating abruptly, after an integral number of bilayers. As the transition is approached the number of layers increases in quantized steps from zero to five before the bulk undergoes a first-order transition to the smectic-A phase.

Second-harmonic microscopy of biological tissue.

Abstract: We present the first reported optical second-harmonic microscope images of a biological sample—rattail tendon—and discuss, also for the first time, the need to distinguish between coherent and incoherent second-harmonic imaging. Our data show that the currently unexplained macroscopic polar order of this classic representative of connective tissue is due both to a coherent network containing a large number of fine, polar, filamentlike structures that permeate the entire tendon volume and to a small number of intensely polar surface patches.

Neural networks with nonlinear synapses and a static noise

Abstract: The theory of neural networks is extended to include a static noise as well as nonlinear updating of synapses by learning. The noise appears either in the form of spin-glass interactions, which are independent of the learning process, or as a random decaying of synapses. In an unsaturated network, the nonlinear learning algorithms may modify the energy surface and lead to interesting new computational capabilities. Close to saturation, they act as an additional source of a static noise. The effect of the noise on memory storage is calculated.

Some properties of a random walk on a comb structure

Abstract: We analyze transport properties of a random walk on a comb structure, which serves as a model for a random walk on the backbone of a percolation cluster. It is shown that the random walk along the x axis, which is the analog of the backbone, exhibits anomalous diffusion in that 〈 x 2 ( n )〉 ∼ n 1 2 , and the expected number of x sites visited is proportional to n 1 4 for large n . The distribution function is found to be a two-dimensional Gaussian. If a field in the x direction, so that diffusion is asymmetric, the expected displacement is found to be asymptotically proportional to n 1 2 .

Weak localization and light scattering from disordered solids.

Abstract: We report the first observation of weak localizations effects in light scattering by a disordered solid. For a diffuse solid scatterer we predict and observe (i) multiple backscattering speckle, (ii) a coherent backscattered peak remaining after removal of this speckle by ensemble averaging, and (iii) speckle statistics which differ from those for single scattering. Computer simulations based upon the theoretical equations yield results in good agreement with experiment.

The joint action of fungicides in mixtures: comparison of two methods for synergy calculation

Abstract: Two methods for evaluating the joint action of fungicides in mixtures were analysed. In order to obtain a relatively rapid answer on the type of interaction between fungicides in a mixture (additivity, synergism or antagonism), one can apply the Abbott formula to data on fungus survival. Tests with this method will not be accurate at high effective dose values. A more accurate determination of the joint action of fungicides can be made by the Wadley method, applied to data on effective doses. This involves more experimental work than the Abbott method. Optimization of mixing ratios of fungicides required a set of experimental data on effective doses with several mixing ratios.

Brain iron-deficiency causes reduced learning capacity in rats.

Abstract: Rats made nutritionally iron-deficient (ID) showed a significant deficit in water-maze learning compared with normal rats. The deficit was substantially greater the longer the rats stayed on the ID diet. The deficit in learning was established prior to any significant decrease in hemoglobin (Hb) level in the blood. Three weeks after the ID rats were placed on a control diet, the Hb level was restored to normal value, but the cognitive deficit remained. Previous studies showed that the behavioral effects of ID are mediated by a decrease in the functional activity of the dopaminergic system. The ID effects on learning and memory may be related to the irreversible diminished dopaminergic neurotransmission that results from ID.

Transfer seeking and avoidance: On the full social costs of rent seeking

Abstract: We would like to thank Gordon Tullock and an anonymous referee of this journal for their helpful comments and suggestions.(This abstract was borrowed from another version of this item.)

Religious observance within a human capital framework: theory and application

Abstract: (1986). Religious observance within a human capital framework: theory and application. Applied Economics: Vol. 18, No. 11, pp. 1193-1202.

The induction of triploidy in Oreochromis aureus by heat shock

Abstract: Triploid fish were obtained using heat-shock treatment. The optimal conditions for the heat shock (39.5±0.2°C for 3.5–4 min) as well as the exact zygote age (3 min) at which this heat shock was applied were studied. Results showed that this treatment gives rise to 100% of triploid fish with a satisfactory survival rate of 61% beyond the yolk sac resorption. The genital papillae of this triploid fish were underdeveloped in comparison to normal diploid fish. However, no morphological or growth-rate differences between diploid and triploid fish could be observed up to the age of 6 months. Triploidy was assessed by the karyotyping of embryo cells or adult PHA-stimulated lymphocytes, or by erythrocyte measurements. The occurrence of a heat-shock sensitive event at the zygotic age of 6 min is discussed.

Matching behavior and collective action: Some experimental evidence

Abstract: A new approach to explaining voluntary collective action, emphasizing strategic interactions of actors in their contributions to the provision of a public good, is tested experimentally. The results support this approach, and tend to reject the conventional, Cournot theory of the provision of public goods. Among the findings are a positive interaction between individual contributions to the provision of a public good, and a U-shaped time trend in combined contributions.

Correlates of Job Satisfaction: A Study of the Two Factor Theory in an Educational Setting

Abstract: This study investigated the generality of the dual factor theory of job satisfaction as proposed by Herzberg, Mausner, and Snyderman (1959). Two questionnaires were employed to examine the sources of job satisfaction and dissatisfaction for elementary school principals in Israel. Results generally supported the two factor theory. Factors designated by Herzberg et al. as satisfiers were dominant sources of job satisfaction in this study as well. A comparison of the answers to the two questionnaires indicated that the attitudes toward the items are usually consistent. Results also showed that the two factor theory is contingent on individual factors.

Attributional processes in the learned helplessness paradigm: Behavioral effects of global attributions.

Abstract: Following the learned helplessness paradigm, I assessed in this study the effects of global and specific attributions for failure on the generalization of performance deficits in a dissimilar situation. Helplessness training consisted of experience with noncontingent failures on four cognitive discrimination problems attributed to either global or specific causes. Experiment 1 found that performance in a dissimilar situation was impaired following exposure to globally attributed failure. Experiment 2 examined the behavioral effects of the interaction between stable and global attributions of failure. Exposure to unsolvable problems resulted in reduced performance in a dissimilar situation only when failure was attributed to global and stable causes. Finally, Experiment 3 found that learned helplessness deficits were a product of the interaction of global and internal attribution. Performance deficits following unsolvable problems were recorded when failure was attributed to global and internal causes. Results were discussed in terms of the reformulated learned helplessness model.

Improved hierarchical bit-vector compression in document retrieval systems

Abstract: The “concordance” of an information retrieval system can often be stored in form of bit-maps, which are usually very sparse and should be compressed. Hierarchical bit-vector compression consists of partitioning a vector vi into equi-sized blocks, constructing a new bit-vector vi+1 which points to the non-zero blocks in vi, dropping the zero-blocks of vi, and repeating the process for vi+1. We refine the method by pruning some of the tree branches if they ultimately point to very few documents; these document numbers are then added to an appended list which is compressed by the prefix-omission technique. The new method was thoroughly tested on the bit-maps of the Responsa Retrieval Project, and gave a relative improvement of about 40% over the conventional hierarchical compression method.

Antioxidant compositions and methods

Abstract: Antioxidant compositions and methods are disclosed that are prepared by the extraction of natural antioxidants from plant substrates.

Risk aversion, terms of trade uncertainty and social-consensus trade policy

Abstract: DEPARTURE from free trade by a small competitive economy can be viewed in terms of conflict or consensus. The conflict perspective, as for example taken in Pincus (1975), Cassing (1981), Hillman (1982), Findlay and Wellisz (1982), Mayer (1984), and Cassing and Hillman (1985), recognizes the diverse interests of the different domestic groups who stand to lose or gain from free trade and emphasises the lobbying by countervailing coalitions to influence the trade policy decisions of politically conscious governments. The alternative consensus perspective notes that trade policy can provide opportunities for risk spreading when insurance markets do not exist; for example, the insurance characteristics of trade policy have been observed by Corden (1974), Hillman (1977), Cassing (1980) and Baldwin (1982). Newbery and Stiglitz (1984) and Eaton and Grossman (1985) have provided more formal demonstrations that risk-averse individuals may benefit from trade intervention which reduces terms of trade variability. This paper presents a further approach of the latter consensus view. Given sufficient risk aversion, the mobile and immobile factors identified in a specific-factors or Ricardo-Viner model are both shown to exhibit an ex-ante preference for reduced relative price variability under terms of trade uncertainty. For a given realization of the terms of trade, factors specific to different sectors are of course in conflict with regard to trade policy, while in the absence of specification of consumption preferences the stance of mobile factors is ambiguous; however, both the conflict and the ambiguity with regard to departure from free trade can disappear if the terms of trade have not been specified. The different groups of factor owners will still differ on the precise ex-ante specification of the departure from free trade for realized terms of trade, although this dissention also disappears if uncertainty is extended to individuals' factor designations.1

Birth Order and Lateral Preferences

Abstract: Associations between birth order and lateral preferences of hand, eye, and foot were examined in a sample of 6436 black seven-year-old boys and girls whose mothers participated in the Collaborative Perinatal Project (CPP) in Philadelphia. Overall, most of the subjects (87%) showed right-hand preference, and the majority of the subjects showed right-eye (55%) and foot (63%) preferences. Analysis of cross preferences indicated some tendency for a consistent right side orientation. However, patterns of lateral preferences were similar for both boys and girls across seven birth order groups. The data were interpreted as showing that birth order and lateral preferences are not interrelated.