175 research outputs found
« Problème ethnique », par le professeur Yaron Tsur. Traduction commentée par Yann Scioldo-Zürcher Levi
No full textThis article is a translation from Hebrew into French of the paper, famous among Israeli historians, “Ethnic Problem” by Professor Yaron Tsur. Looking at the first Jewish ethnic riots that took place in 1959 in the city of Haïfa, the author details both the chronology that led to the Eastern migrants imposing themselves in the political landscape of the State, but also the social-political processes that that had, until then, forced them to live on the margins of Israeli society. This annotated translation is aimed at readers interested in Israeli Area Studies, but also for those who interest in the way populations are “structured” by one State created in the second half of the twentieth centur
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Capitalism vs Socialism Debate
No full textWatch Yaron Brook - Chairman of the Board, Ayn Rand Institute - and Bhaskar Sunkara - Author of “The Socialist Manifesto: The Case for Radical Politics in an Era of Extreme Inequality”- debating about the merits and prospects of Capitalism and Socialism.Salem Cente
Wiring the Nervous System
No full textThis book examines recent key findings on the mechanisms of axonal and dendritic remodeling in different model organisms. Each chapter is contributed by a panel of experts in their respective subfields of neurosciences, to provide and discuss the latest discoveries ranging from neuronal morphogenesis during development, experience-dependent structural plasticity, to neuronal degeneration, regeneration, and pathologies in neurological disorders.
The process of neuronal remodeling, specifically their axons and dendrites, is essential for the proper wiring of the nervous system during early development and continues during postnatal ages to shape the pattern of synaptic connections throughout the life of the organism, including humans. Over recent years, substantial progress has been made in our understanding of the cellular and molecular mechanisms that control neuronal remodeling. In addition, there is accumulating evidence demonstrating how the nervous system could remodel in response to injury and in pathological conditions.
Topics discussed in the book include:
Axonal degeneration during development and in pathological or disease conditions
Neuronal morphogenesis (axons and dendrites)
Experience-dependent structural plasticity to synaptogenesis
Dendrite degeneration and regeneratio
Yemenite Jews in Israeli Cinema
No full textThe bachelor's thesis explores the representation of Yemenite identity in Israeli cinema across different historical periods. It focuses on how these representations reflected broader social and political changes in Israel. The thesis is theoretically based on postcolonial theory and cultural studies, through applying textual and intertextual analyses based on the approaches of Ella Shohat and Yaron Shemer to six films about Yemeni Jews from the 1950s to the present. Key themes include the hybridization of film characters, the use of language, the representation of Yemeni customs and history, and the role of production in shaping film narratives. The work traces the transformation of stereotyped and exoticized characters into deeper and more complex protagonists. The result is a new perspective on the study of ethnic groups with cultural heritage in Israeli cinema and their impact on the contemporary understanding of Israeli society beyond the Ashkenazim/Mizrahim dichotomy. Keywords: Israeli cinema, Yemeni identity, Mizrahi Jews, postcolonial theory, minority representation in fil
Molecular mechanisms of semaphorin 3A-Neuropilin1 / Plexin-A4 signaling in layer 5 pyramidal neurons of the mouse cortex during development
No full textThe proper establishment of neuronal circuits is of ultimate importance to the functionality of an organism as a whole. Neuronal circuit development is a complex process that largely revolves around the formation of the correct neuronal morphologies through directional growth and maturation of neurites, i.e., axons and dendrites. This is achieved through multiple developmental stages such as neuronal polarization, neurite outgrowth, guidance, synaptogenesis, and neurite pruning. The formation of abnormal neuronal connections due to aberrant dendritic morphologies, in particular, has been shown to contribute to a variety of neurological disorders such as autism spectrum disorders (ASDs), Schizophrenia, and epilepsy, just to name a few. The neurodevelopmental processes of neurite outgrowth and guidance are largely dependent on extracellular guidance cues. These cues mediate their effects through the regulation of cytoskeletal components, actin and microtubules, leading to morphological changes in neurites. A number of guidance cue families such as Slits, Netrins, Ephrins and Semaphorins have been shown to act as attractants or repellents for neurites during development. The semaphorins, a large family of secreted and membrane-bound guidance cues, were initially identified as repellents in axon guidance events. They have also been described in other crucial cellular processes that contribute to the formation of neuronal connections including, but not limited to, dendritic morphogenesis and synaptic development. Of particular interest, the class 3 secreted semaphorin 3A (Sema3A), signaling through its receptor complex Neuropilin-1 (Nrp1) / PlexinA4 (PlxnA4), has been shown to promote dendritic morphogenesis in cortical neuron development in vitro and in vivo. However, the underlying intracellular mechanisms employed by Sema3A-Nrp1/PlxnA4 signaling to control dendritic elaboration remain elusive. Furthermore, it is not clear whether dendritic development (positive effect) mediated by Sema3A-Nrp1/PlxnA4 employs the same or similar intracellular signaling pathways as those proposed for axon guidance (negative effect). Therefore, I asked these main questions in my thesis work: 1) Is the LVS motif in the H/RBD domain of the Plexin-A4 receptor required for Sema3A-mediated dendritic elaboration in vivo and in vitro? 2) Does Sema3A-mediated dendritic elaboration involve transcriptional and/or translational regulation, as seen in some Sema3A-mediated axon guidance events, in vitro? And 3) What are the potential novel downstream effectors in Sema3A-mediated dendritic elaboration in cortical pyramidal neuron development?
To address the above questions, first I characterized the role of the LVS motif in the H/RBD cytoplasmic domain of the PlexinA4 receptor in layer 5 cortical neuron dendrite development. I showed that the LVS motif is required for basal dendritic branching and growth in vivo and in vitro following Sema3A treatment. Upon Sema3A binding to the Nrp1/PlxnA4 holoreceptor complex, the small Rnd1 GTPase is able to bind the PlxnA4 receptor at the LVS motif. In addition, siRNA knockdown of Rnd1 showed its requirement for Sema3A-induced dendritic elaboration. Next, I showed that the activity of the small RhoA GTPase is downregulated in wild type primary cortical neurons following Sema3A treatment, but not in PlxnA4LVS-GGA/LVS-GGA mutant neurons. The inactivation of RhoA following Sema3A treatment is supported by consequential inhibition of ROCK, which is downstream of RhoA signaling. Moreover, I also showed that the overexpression of the small GTPase Rac1 in PlxnA4LVS-GGA/LVS-GGA mutant neurons is able to rescue the dendritic phenotypes observed in vitro. Taken together, my findings suggest that Sema3A-Nrp1/PlxnA4-LVS interaction with the Rnd1 GTPase to decrease the activity of RhoA and ROCK downstream signaling leads to the permissive growth and branching of dendrites in developing mouse cortical neurons. To address the question of whether Sema3A-mediated dendritic elaboration also requires transcriptional and/or translational regulation, I took a pharmacological approach. Using transcriptional and translational inhibitors, I showed that primary cortical neurons no longer respond to Sema3A-induced dendritic branching and growth. I dissected the temporal windows at which each of these two mechanisms are employed during Sema3A-induced dendritic elaboration in vitro. Specifically, I showed that gene transcription is required as early as 30 minutes following Sema3A treatment up to 3 hours. I also found that protein translation is required starting at ~1 hour following Sema3A signaling up to 8 hours. Collectively, my findings suggest that gene transcription and protein translation are employed during the initial stages of Sema3A-induced dendritic branching in mouse cortical neurons in vitro. Finally, to determine the novel gene expression profile changes following Sema3A signaling in developing cortical neurons, I performed RNA sequencing (in collaboration with the Genomics Center, Rutgers NJ Medical School) in primary cortical neurons taken from the RiboTag mouse (where the Rpl22 protein is HA-tagged and floxed) crossed with the Etv1-CreERT2 driver line. Indeed, many genes are differentially regulated following Sema3A treatment as summarized in this thesis. Future experiments are required to verify which specific genes are involved in Sema3A-mediated dendritic elaboration versus axon guidance events. Taken together, the results in my thesis research provided novel insights to the intracellular mechanisms underlying Sema3A-Nrp1/PlxnA4-mediated dendritic morphogenesis during cortical development in vivo and in vitro. I also showed that both gene transcription and protein translation are required for Sema3A signaling in vitro and have identified a substantial number of potential candidates that are differentially regulated. Overall, my findings provided new knowledge that leads to a better understanding of the molecular mechanisms controlling neuronal connectivity in the developing mammalian neocortex.Ph.D.Includes bibliographical reference
Reducing uncertainty in operational problems
No full textThesis: Ph. D., Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 205-207).Motivated by several core operational applications, we introduce a class of multistage stochastic optimization models that capture a fundamental tradeoff between performing work under uncertainty (exploitation) and investing resources to reduce the uncertainty in the decision making (exploration/testing). Unlike existing models, in which the exploration-exploitation tradeoffs typically relate to learning the underlying distributions, the models we introduce assume a known probabilistic characterization of the uncertainty, and focus on the tradeoff of learning exact realizations. In the first part of the thesis (Chapter 2), we study a class of scheduling problems that capture common settings in service environments in which the service provider must serve a collection of jobs that have a-priori uncertain processing times and priorities (modeled as weights). In addition, the service provider must decide how to dynamically allocate capacity between processing jobs and testing jobs to learn more about their respective processing times and weights. We obtain structural results of optimal policies that provide managerial insights, efficient optimal and near-optimal algorithms, and quantification of the value of testing. In the second part of the thesis (Chapter 3), we generalize the model introduced in the first part by studying how to prioritize testing when jobs have different uncertainties. We model difference in uncertainties using the convex order, a general relation between distributions, which implies that the variance of one distribution is higher than the variance of the other distribution. Using an analysis based on the concept of mean preserving local spread, we show that the structure of the optimal policy generalizes that of the initial model where jobs were homogeneous and had equal weights. Finally, in the third part of the thesis (Chapter 4), we study a broad class of stochastic combinatorial optimization that can be formulated as Linear Programs whose objective coefficients are random variables that can be tested, and whose constraint polyhedron has the structure of a polymatroid. We characterize the optimal policy and show that similar types of policies optimally govern testing decisions in this setting as well.by Yaron Shaposhnik.Ph. D
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