The Fiber Walk: A Model of Tip-Driven Growth with Lateral Expansion

Tip-driven growth processes underlie the development of many plants. To date, tip-driven growth processes have been modelled as an elongating path or series of segments without taking into account lateral expansion during elongation. Instead, models of growth often introduce an explicit thickness by expanding the area around the completed elongated path. Modelling expansion in this way can lead to contradictions in the physical plausibility of the resulting surface and to uncertainty about how the object reached certain regions of space. Here, we introduce "fiber walks" as a self-avoiding random walk model for tip-driven growth processes that includes lateral expansion. In 2D, the fiber walk takes place on a square lattice and the space occupied by the fiber is modelled as a lateral contraction of the lattice. This contraction influences the possible follow-up steps of the fiber walk. The boundary of the area consumed by the contraction is derived as the dual of the lattice faces adjacent to the fiber. We show that fiber walks generate fibers that have well-defined curvatures, enable the identification of the process underlying the occupancy of physical space. Hence, fiber walks provide a base from which to model both the extension and expansion of physical biological objects with finite thickness.Comment: Plos One (in press

The realization of the detailed local plans in urban areas in Turkey: a model

The main objective of the realization of local physical plan in urban areas is to constitute the healthy urban structure, to provide land development and to regulate the use of private and public land for public interest. The other important objective is to prevent sprawl of city and chaotic growth. The realization of local physical plan is a process which it express the change in an urban area from irregular plots of rural land to urban plots having infrastructure according to local physical plans. The municipalities are responsible for the realization of local physical urban plans in Turkey. There is not any sufficient research related to realization of local physical plans in urban spaces throughout the Turkey. The purpose of this study is to investigate whether there is a relationship between the realization rate of local physical plans and population, population growth rate, socio-economic index, the number of technical personnel, some dummy variables. For this research, a sample survey method is used and 468 questionnaires are completed by Planning Office of the municipalities of urban areas in Turkey. In this model, the index of realization local physical plan are used as a dependent variable and population, population growth rate, global density in urban areas according to detailed plans, adequacy of budgets, socio-economic index, the number of personnel, Multiple Regression Model is utilized for Turkey. The results of the paper can be used to identify the problems concerning the realization of local physical plans and to suggest solutions to these problems based on existing legislation in Turkey in international context.

The realization of the detailed local plans in urban areas in Turkey: a model

The main objective of the realization of local physical plan in urban areas is to constitute the healthy urban structure, to provide land development and to regulate the use of private and public land for public interest. The other important objective is to prevent sprawl of city and chaotic growth. The realization of local physical plan is a process which it express the change in an urban area from irregular plots of rural land to urban plots having infrastructure according to local physical plans. The municipalities are responsible for the realization of local physical urban plans in Turkey. There is not any sufficient research related to realization of local physical plans in urban spaces throughout the Turkey. The purpose of this study is to investigate whether there is a relationship between the realization rate of local physical plans and population, population growth rate, socio-economic index, the number of technical personnel, some dummy variables. For this research, a sample survey method is used and 468 questionnaires are completed by Planning Office of the municipalities of urban areas in Turkey. In this model, the index of realization local physical plan are used as a dependent variable and population, population growth rate, global density in urban areas according to detailed plans, adequacy of budgets, socio-economic index, the number of personnel, Multiple Regression Model is utilized for Turkey. The results of the paper can be used to identify the problems concerning the realization of local physical plans and to suggest solutions to these problems based on existing legislation in Turkey in international context

Pulsar extinction

Radio emission from pulsars, attributed to an instability associated with the creation of electron-positron pairs from gamma rays was investigated. The condition for pair creation therefore lead to an extinction condition. The relevant physical processes were analyzed in the context of a mathematical model, according to which radiation originated at the polar caps and magnetic field lines changed from a closed configuration to an open configuration at the force balance or corotation radius

The association between the prevalence of restless leg syndrome, fatigue, and sleep quality in patients undergoing hemodialysis

Objective: To determine the prevalence of restless legs syndrome (RLS) in patients with chronic renal failure (CRF) and to compare CRF patients with or without RLS in terms fatigue and sleep quality. Methods: A cross-sectional study was conducted on 220 patients (18-75 years) who were undergoing dialysis 3 times weekly in Çorum Province, Corum, Turkey, between January 2014 and January 2016. The diagnosis of RLS was based on the diagnostic form proposed by the international RLS study group. Sleep quality was evaluated using the Pittsburgh sleep quality index (PSQI), and severity of fatigue was determined by using fatigue severity scale (FSS). Results: Of all the participants, 16.8% (n= 37) (Group 1) were found to have RLS, while 183 patients had no RLS (Group 2). The mean ages were similar between groups. With respect to laboratory analyses, a p-value of <0.05 was considered in Group 1 than in Group 2. Restless legs syndrome was mild (7.1%), moderate (46.4%) and severe (39.3%) in patients with RLS. Factors associated with the severity of RLS included weight, duration of dialysis, anuria, iron, total iron binding capacity, calcium and transferrin saturation. The PSQI and FSS scores were significantly worse in Group 1 (p<0.001). Conclusion: Restless legs syndrome is a common condition in patients undergoing hemodialysis; the results of our study confirm the adverse effects of RLS in terms of many aspects of sleep quality and fatigue. © 2018, Saudi Arabian Armed Forces Hospital. All rights reserved

HIL: designing an exokernel for the data center

We propose a new Exokernel-like layer to allow mutually untrusting physically deployed services to efficiently share the resources of a data center. We believe that such a layer offers not only efficiency gains, but may also enable new economic models, new applications, and new security-sensitive uses. A prototype (currently in active use) demonstrates that the proposed layer is viable, and can support a variety of existing provisioning tools and use cases.Partial support for this work was provided by the MassTech Collaborative Research Matching Grant Program, National Science Foundation awards 1347525 and 1149232 as well as the several commercial partners of the Massachusetts Open Cloud who may be found at http://www.massopencloud.or

An Experiment on Bare-Metal BigData Provisioning

Many BigData customers use on-demand platforms in the cloud, where they can get a dedicated virtual cluster in a couple of minutes and pay only for the time they use. Increasingly, there is a demand for bare-metal bigdata solutions for applications that cannot tolerate the unpredictability and performance degradation of virtualized systems. Existing bare-metal solutions can introduce delays of 10s of minutes to provision a cluster by installing operating systems and applications on the local disks of servers. This has motivated recent research developing sophisticated mechanisms to optimize this installation. These approaches assume that using network mounted boot disks incur unacceptable run-time overhead. Our analysis suggest that while this assumption is true for application data, it is incorrect for operating systems and applications, and network mounting the boot disk and applications result in negligible run-time impact while leading to faster provisioning time.This research was supported in part by the MassTech Collaborative Research Matching Grant Program, NSF awards 1347525 and 1414119 and several commercial partners of the Massachusetts Open Cloud who may be found at http://www.massopencloud.or

Placental Flattening via Volumetric Parameterization

We present a volumetric mesh-based algorithm for flattening the placenta to a canonical template to enable effective visualization of local anatomy and function. Monitoring placental function in vivo promises to support pregnancy assessment and to improve care outcomes. We aim to alleviate visualization and interpretation challenges presented by the shape of the placenta when it is attached to the curved uterine wall. To do so, we flatten the volumetric mesh that captures placental shape to resemble the well-studied ex vivo shape. We formulate our method as a map from the in vivo shape to a flattened template that minimizes the symmetric Dirichlet energy to control distortion throughout the volume. Local injectivity is enforced via constrained line search during gradient descent. We evaluate the proposed method on 28 placenta shapes extracted from MRI images in a clinical study of placental function. We achieve sub-voxel accuracy in mapping the boundary of the placenta to the template while successfully controlling distortion throughout the volume. We illustrate how the resulting mapping of the placenta enhances visualization of placental anatomy and function. Our code is freely available at https://github.com/mabulnaga/placenta-flattening .Comment: MICCAI 201

Optical radiation from the Crab pulsar

Possible mechanisms for producing the optical radiation from the Crab pulsar are proposed and discussed. There are severe difficulties in interpreting the radiation as being produced by an incoherent process, whether it be synchrotron radiation, inverse-Compton radiation or curvature radiation. It is proposed therefore that radiation in the optical part of the spectrum is coherent. In the polar cap model, a small bunch of electrons and positrons forms near each primary electron as a result of the pair-production cascade process. Ambient electric fields give rise to energy separation, as a result of which either the electrons or positrons will dominate the radiation from each bunch. The roll-off in the infrared is ascribed to synchrotron absorption by electrons and positrons located between the surface of the star and the force-balance radius. Various consequences of this model, which may be subjected to observational test, are discussed