206 research outputs found

    Exact moments in a continuous time random walk with complete memory of its history

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    We present a continuous time generalization of a random walk with complete memory of its history [Phys. Rev. E 70, 045101(R) (2004)] and derive exact expressions for the first four moments of the distribution of displacement when the number of steps is Poisson distributed. We analyze the asymptotic behavior of the normalized third and fourth cumulants and identify new transitions in a parameter regime where the random walk exhibits superdiffusion. These transitions, which are also present in the discrete time case, arise from the memory of the process and are not reproduced by Fokker-Planck approximations to the evolution equation of this random walk.Comment: Revtex4, 10 pages, 2 figures. v2: applications discussed, clarity improved, corrected scaling of third momen

    Philippine employment in the seventies

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    One of the most important development challenges that confronts the Philippines in the years ahead is the need to provide jobs to the currently unemployed and underemployed members of the labor force as well as to the 600,000_650,000 persons who join the labor force every year. Accordingly, employment promotion remains a high priority in our country's total development efforts. This study on Philippine employment in the seventies by Rosa Linda P. Tidalgo and Emmanuel F. Esguerra presents valuable information and insights on the Philippine employment scenario. It reviews the findings and recommendations of employment research, highlights the employment experience in the 70's, evaluates the overall policy framework for employment promotion, assesses the state of Philippine employment statistics,and indicates the factors which should be considered in formulating employment policy. The problems identified in the study, e.g., the capital-bias promoted by the structure of economic incentives and pattern of industrialization; the failure of the industrial sector to absorb labor from agriculture; the need for timely and accurate information on employment; and the need to harmonize employment policies with other development policies, do not require further emphasis.Certainly, sustained national development depends a great deal on how these problems are approached and resolved. It is hoped that this study can in one way or another assist in promoting more effective and consistent employment policies and programs in the future

    Brownian motion of a charged particle driven internally by correlated noise

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    We give an exact solution to the generalized Langevin equation of motion of a charged Brownian particle in a uniform magnetic field that is driven internally by an exponentially-correlated stochastic force. A strong dissipation regime is described in which the ensemble-averaged fluctuations of the velocity exhibit transient oscillations that arise from memory effects. Also, we calculate generalized diffusion coefficients describing the transport of these particles and briefly discuss how they are affected by the magnetic field strength and correlation time. Our asymptotic results are extended to the general case of internal driving by correlated Gaussian stochastic forces with finite autocorrelation times.Comment: 10 pages, 4 figures with subfigures, RevTeX, v2: revise

    A circular RNA generated from an intron of the insulin gene controls insulin secretion.

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    Fine-tuning of insulin release from pancreatic β-cells is essential to maintain blood glucose homeostasis. Here, we report that insulin secretion is regulated by a circular RNA containing the lariat sequence of the second intron of the insulin gene. Silencing of this intronic circular RNA in pancreatic islets leads to a decrease in the expression of key components of the secretory machinery of β-cells, resulting in impaired glucose- or KCl-induced insulin release and calcium signaling. The effect of the circular RNA is exerted at the transcriptional level and involves an interaction with the RNA-binding protein TAR DNA-binding protein 43 kDa (TDP-43). The level of this circularized intron is reduced in the islets of rodent diabetes models and of type 2 diabetic patients, possibly explaining their impaired secretory capacity. The study of this and other circular RNAs helps understanding β-cell dysfunction under diabetes conditions, and the etiology of this common metabolic disorder

    A circular RNA generated from an intron of the insulin gene controls insulin secretion

    Get PDF
    Fine-tuning of insulin release from pancreatic β-cells is essential to maintain blood glucose homeostasis. Here, we report that insulin secretion is regulated by a circular RNA containing the lariat sequence of the second intron of the insulin gene. Silencing of this intronic circular RNA in pancreatic islets leads to a decrease in the expression of key components of the secretory machinery of β-cells, resulting in impaired glucose- or KCl-induced insulin release and calcium signaling. The effect of the circular RNA is exerted at the transcriptional level and involves an interaction with the RNA-binding protein TAR DNA-binding protein 43 kDa (TDP-43). The level of this circularized intron is reduced in the islets of rodent diabetes models and of type 2 diabetic patients, possibly explaining their impaired secretory capacity. The study of this and other circular RNAs helps understanding β-cell dysfunction under diabetes conditions, and the etiology of this common metabolic disorder
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