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Search Results: 1 - 10 of 9012 matches for " Ben Zion Sandler "
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Vibrating Drivers for Transportation  [PDF]
Ben Zion Sandler, Vladimir Chapsky
Modern Mechanical Engineering (MME) , 2013, DOI: 10.4236/mme.2013.32011
Abstract:

The movement of objects by means of vibrations is a widely known idea, used for bodies transportation in automated industry based on vibrating bases, on which the transported elements are placed. We consider an inversed idea: vibration is applied to the movable element. Surface, on which this displacement must be realized, is unmovable. The asymmetry of the friction forces in the different phases of the vibration is the cause of motion in this case. A distinctive feature of the proposed device is a slope of the plane of vibration of the inertial mass, which leads to increasing of the asymmetry of friction. In this paper, we consider an example of application of the device to the lateral vehicle parking. The idea is numerically estimated and tested with a laboratory prototype. The movement along a straight line of the trolley with sloped vibrating mechanism under influence of asymmetric friction forces has been estimated and practically simulated with the laboratory prototype.

Pre-Steady-State Decoding of the Bicoid Morphogen Gradient
Sven Bergmann,Oded Sandler,Hila Sberro,Sara Shnider,Eyal Schejter,Ben-Zion Shilo,Naama Barkai
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0050046
Abstract: Morphogen gradients are established by the localized production and subsequent diffusion of signaling molecules. It is generally assumed that cell fates are induced only after morphogen profiles have reached their steady state. Yet, patterning processes during early development occur rapidly, and tissue patterning may precede the convergence of the gradient to its steady state. Here we consider the implications of pre-steady-state decoding of the Bicoid morphogen gradient for patterning of the anterior–posterior axis of the Drosophila embryo. Quantitative analysis of the shift in the expression domains of several Bicoid targets (gap genes) upon alteration of bcd dosage, as well as a temporal analysis of a reporter for Bicoid activity, suggest that a transient decoding mechanism is employed in this setting. We show that decoding the pre-steady-state morphogen profile can reduce patterning errors caused by fluctuations in the rate of morphogen production. This can explain the surprisingly small shifts in gap and pair-rule gene expression domains observed in response to alterations in bcd dosage.
Pre-Steady-State Decoding of the Bicoid Morphogen Gradient
Sven Bergmann,Oded Sandler,Hila Sberro,Sara Shnider,Eyal Schejter,Ben-Zion Shilo,Naama Barkai
PLOS Biology , 2007, DOI: 10.1371/journal.pbio.0050046
Abstract: Morphogen gradients are established by the localized production and subsequent diffusion of signaling molecules. It is generally assumed that cell fates are induced only after morphogen profiles have reached their steady state. Yet, patterning processes during early development occur rapidly, and tissue patterning may precede the convergence of the gradient to its steady state. Here we consider the implications of pre-steady-state decoding of the Bicoid morphogen gradient for patterning of the anterior–posterior axis of the Drosophila embryo. Quantitative analysis of the shift in the expression domains of several Bicoid targets (gap genes) upon alteration of bcd dosage, as well as a temporal analysis of a reporter for Bicoid activity, suggest that a transient decoding mechanism is employed in this setting. We show that decoding the pre-steady-state morphogen profile can reduce patterning errors caused by fluctuations in the rate of morphogen production. This can explain the surprisingly small shifts in gap and pair-rule gene expression domains observed in response to alterations in bcd dosage.
Clinical Outcome of Conservative Treatment of Displaced Mandibular Fracture in Adults  [PDF]
Lipa Bodner, Sigal Amitay, Ben Zion Joshua
Surgical Science (SS) , 2013, DOI: 10.4236/ss.2013.411097
Abstract:

The article evaluates 12 cases of conservative treatment of displaced mandibular fractures in adults. Twelve cases of displaced mandibular fractures treated surgically, either by closed reduction (IMF) or open reduction internal fixation (ORIF) served as controls. Occlusion, maximal mouth opening, lateral jaw movements, neurological dysfunction (=sensory deficit), and bone remodeling were evaluated and scored in both groups, and results were compared. No significant differences were found between the two groups in all the evaluated parameters. It is concluded that in certain cases, with displacement of 2 - 4 mm, where a surgical approach is not feasible, reasonable spontaneous reduction and bone remodeling can occur. Meticulous follow-up is mandatory.

On a class of one-sided Markov shifts
Ben-Zion Rubshtein
Mathematics , 2004,
Abstract: We study one-sided Markov shifts, corresponding to positively recurrent Markov chains with countable (finite or infinite) state spaces. The following classification problem is considered: when two one-sided Markov shifts are isomorphic up to a measure preserving isomorphism In this paper we solve the problem for the class of rho-uniform (or finitely rho-Bernoulli) one-sided Markov shifts considered in Ru_6 We show that every ergodic rho-uniform Markov shift T can be represented in a canonical form T = T_G by means of a canonical (uniquely determined by T) stochastic graph G. In the canonical form, two such shifts T_{G_1} and T_{G_2} are isomorphic if and only if their canonical stochastic graphs G_1 and G_2 are isomorphic.
Controlling Effect of Geometrically Defined Local Structural Changes on Chaotic Hamiltonian Systems
Yossi Ben Zion,Lawrence Horwitz
Physics , 2010, DOI: 10.1103/PhysRevE.81.046217
Abstract: An effective characterization of chaotic conservative Hamiltonian systems in terms of the curvature associated with a Riemannian metric tensor derived from the structure of the Hamiltonian has been extended to a wide class of potential models of standard form through definition of a conformal metric. The geodesic equations reproduce the Hamilton equations of the original potential model through an inverse map in the tangent space. The second covariant derivative of the geodesic deviation in this space generates a dynamical curvature, resulting in (energy dependent) criteria for unstable behavior different from the usual Lyapunov criteria. We show here that this criterion can be constructively used to modify locally the potential of a chaotic Hamiltonian model in such a way that stable motion is achieved. Since our criterion for instability is local in coordinate space, these results provide a new and minimal method for achieving control of a chaotic system.
Language Development: The Effect of Aquatic and On-Land Motor Interventions  [PDF]
Ronit Ram-Tsur, Michal Nissim, Michal Zion, Tal Dotan Ben-Soussan, Zemira Mevarech
Creative Education (CE) , 2013, DOI: 10.4236/ce.2013.49B009
Abstract:

The aim of the current preliminary research was to examine the relationship between aquatic motor activities and language abilities. Our hypothesis suggests that changing the environment to water may improve motor and linguistic abilities. The study included 94 children between the ages of four and six. Thirty-one children who participated in aquatic motor activities were compared to 41 children who participated in on-land motor activities and to 21 children who participated in non-motor activities. Developmental-functionality tests, including gross and fine motor, time estimation and language tests, were used to diagnose participants’ abilities before and after six months of intervention. We found significant improvement in gross motor, fine motor and time estimation abilities for the aquatic motor activities group. Moreover, improvement in gross motor and time estimation abilities moderated the association between aquatic motor activities and children’s naming ability, suggesting the positive effect of aquatic motor activities on language abilities. Based on these novel findings, child-development professionals can have a better understanding of relation between language abilities and motor abilities, possibly leading to an improvement of intervention methods with early-childhood patients. Early childhood intervention could aid in reducing primary differences between children in motor abilities, and especially in motor-development disorders, which in turn are thought to lead to additional learning disabilities.

Effects of Aquatic Motor Activities on Early Childhood Cognitive and Motor Development  [PDF]
Michal Nissim, Ronit Ram-Tsur, Michal Zion, Zemira Mevarech, Tal Dotan Ben-Soussan
Open Journal of Social Sciences (JSS) , 2014, DOI: 10.4236/jss.2014.212005
Abstract: While the mental and physical benefits of motor activity are well documented, the degree to which these benefits are dependent upon the environment within which the activity takes place remains unknown. Specifically, studies exploring the effects of aquatic motor activities on cognitive abilities are rare. The current study investigated the effects of aquatic motor activities—as compared to on-land motor activities and non-motor activities—on the development of motor and cognitive abilities in a sample of 94 children aged between four and six. Developmental-functionality tests—including fine and gross motor, time estimation, reasoning and processing speed tests—were used to measure the motor and cognitive abilities of participants before and after six months of intervention. Participation in the aquatic motor activities group was found to improve gross motor, time-estimation and reasoning abilities. Moreover, improvements in gross motor abilities mediated the association between participation in aquatic motor activities group and the children’s processing speed ability. These findings can improve the understanding of child development professionals, psychologists and educators regarding the connection between aquatic environment and cognitive and motor development, and may contribute to improved early childhood interventions.
Optimizing Metapopulation Sustainability through a Checkerboard Strategy
Yossi Ben Zion ,Gur Yaari,Nadav M. Shnerb
PLOS Computational Biology , 2010, DOI: 10.1371/journal.pcbi.1000643
Abstract: The persistence of a spatially structured population is determined by the rate of dispersal among habitat patches. If the local dynamic at the subpopulation level is extinction-prone, the system viability is maximal at intermediate connectivity where recolonization is allowed, but full synchronization that enables correlated extinction is forbidden. Here we developed and used an algorithm for agent-based simulations in order to study the persistence of a stochastic metapopulation. The effect of noise is shown to be dramatic, and the dynamics of the spatial population differs substantially from the predictions of deterministic models. This has been validated for the stochastic versions of the logistic map, the Ricker map and the Nicholson-Bailey host-parasitoid system. To analyze the possibility of extinction, previous studies were focused on the attractiveness (Lyapunov exponent) of stable solutions and the structure of their basin of attraction (dependence on initial population size). Our results suggest that these features are of secondary importance in the presence of stochasticity. Instead, optimal sustainability is achieved when decoherence is maximal. Individual-based simulations of metapopulations of different sizes, dimensions and noise types, show that the system's lifetime peaks when it displays checkerboard spatial patterns. This conclusion is supported by the results of a recently published Drosophila experiment. The checkerboard strategy provides a technique for the manipulation of migration rates (e.g., by constructing corridors) in order to affect the persistence of a metapopulation. It may be used in order to minimize the risk of extinction of an endangered species, or to maximize the efficiency of an eradication campaign.
Polarized Secretion of Drosophila EGFR Ligand from Photoreceptor Neurons Is Controlled by ER Localization of the Ligand-Processing Machinery
Shaul Yogev,Eyal D. Schejter,Ben-Zion Shilo
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.1000505
Abstract: The release of signaling molecules from neurons must be regulated, to accommodate their highly polarized structure. In the developing Drosophila visual system, photoreceptor neurons secrete the epidermal growth factor receptor ligand Spitz (Spi) from their cell bodies, as well as from their axonal termini. Here we show that subcellular localization of Rhomboid proteases, which process Spi, determines the site of Spi release from neurons. Endoplasmic reticulum (ER) localization of Rhomboid 3 is essential for its ability to promote Spi secretion from axons, but not from cell bodies. We demonstrate that the ER extends throughout photoreceptor axons, and show that this feature facilitates the trafficking of the Spi precursor, the ligand chaperone Star, and Rhomboid 3 to axonal termini. Following this trafficking step, secretion from the axons is regulated in a manner similar to secretion from cell bodies. These findings uncover a role for the ER in trafficking proteins from the neuronal cell body to axon terminus.
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