SUPERMARKET CHARACTERISTICS AND OPERATING COSTS IN LOW-INCOME AREAS

Whether the poor pay more for food than other income groups is an important question in food price policy research. Stores serving low-income shoppers differ in important ways from stores that receive less of their revenues from Food Stamp redemptions. Stores with more revenues from Food Stamps are generally smaller and older, and offer relatively fewer convenience services for shoppers. They also offer a different mix of products, with a relatively high portion of sales coming from meat and private-label products. Metro stores with high Food Stamp redemption rates lag behind other stores in the adoption of progressive supply chain and human resource practices. Finally, stores with the highest Food Stamp redemption rates have lower sales margins relative to other stores, but have significantly lower payroll costs as a percentage of sales. Overall, operating costs for stores with high Food Stamp redemption rates are not significantly different from those for stores with moderate Food Stamp redemption rates. If the poor do pay more, factors other than operating costs are likely to be the reason.Food prices, supermarkets, low-income consumers, Food Stamps, metro, nonmetro, Marketing,

A study of the local convergence of a fifth order iterative method

[EN] We present a local convergence study of a fifth order iterative method to approximate a locally unique root of nonlinear equations. The analysis is discussed under the assumption that first order Frechet derivative satisfies the Lipschitz continuity condition. Moreover, we consider the derivative free method that obtained through approximating the derivative with divided difference along with the local convergence study. Finally, we provide computable radii and error bounds based on the Lipschitz constant for both cases. Some of the numerical examples are worked out and compared the results with existing methods.This research was partially supported by Ministerio de Economia y Competitividad under grant PGC2018-095896-B-C21-C22.Singh, S.; Martínez Molada, E.; Maroju, P.; Behl, R. (2020). A study of the local convergence of a fifth order iterative method. Indian Journal of Pure and Applied Mathematics. 51(2):439-455. https://doi.org/10.1007/s13226-020-0409-5S439455512A. Constantinides and N. Mostoufi, Numerical Methods for Chemical Engineers with MATLAB Applications, Prentice Hall PTR, New Jersey, (1999).J. M. Douglas, Process Dynamics and Control, Prentice Hall, Englewood Cliffs, (1972).M. Shacham, An improved memory method for the solution of a nonlinear equation, Chem. Eng. Sci., 44 (1989), 1495–1501.J. M. Ortega and W. C. Rheinboldt, Iterative solution of nonlinear equations in several variables, Academic Press, New-York, (1970).J. R. Sharma and H. Arora, A novel derivative free algorithm with seventh order convergence for solving systems of nonlinear equations, Numer. Algorithms, 67 (2014), 917–933.I. K. Argyros, A. A. Magreńan, and L. Orcos, Local convergence and a chemical application of derivative free root finding methods with one parameter based on interpolation, J. Math. Chem., 54 (2016), 1404–1416.E. L. Allgower and K. Georg, Lectures in Applied Mathematics, American Mathematical Society (Providence, RI) 26, 723–762.A. V. Rangan, D. Cai, and L. Tao, Numerical methods for solving moment equations in kinetic theory of neuronal network dynamics, J. Comput. Phys., 221 (2007), 781–798.A. Nejat and C. Ollivier-Gooch, Effect of discretization order on preconditioning and convergence of a high-order unstructured Newton-GMRES solver for the Euler equations, J. Comput. Phys., 227 (2008), 2366–2386.C. Grosan and A. Abraham, A new approach for solving nonlinear equations systems, IEEE Trans. Syst. Man Cybernet Part A: System Humans, 38 (2008), 698–714.F. Awawdeh, On new iterative method for solving systems of nonlinear equations, Numer. Algorithms, 54 (2010), 395–409.I. G. Tsoulos and A. Stavrakoudis, On locating all roots of systems of nonlinear equations inside bounded domain using global optimization methods, Nonlinear Anal. Real World Appl., 11 (2010), 2465–2471.E. Martínez, S. Singh, J. L. Hueso, and D. K. Gupta, Enlarging the convergence domain in local convergence studies for iterative methods in Banach spaces, Appl. Math. Comput., 281 (2016), 252–265.S. Singh, D. K. Gupta, E. Martínez, and J. L. Hueso, Semi local and local convergence of a fifth order iteration with Fréchet derivative satisfying Hölder condition, Appl. Math. Comput., 276 (2016), 266–277.I. K. Argyros and S. George, Local convergence of modified Halley-like methods with less computation of inversion, Novi. Sad.J. Math., 45 (2015), 47–58.I. K. Argyros, R. Behl, and S. S. Motsa, Local Convergence of an Efficient High Convergence Order Method Using Hypothesis Only on the First Derivative Algorithms 2015, 8, 1076–1087; doi:https://doi.org/10.3390/a8041076.A. Cordero, J. L. Hueso, E. Martínez, and J. R. Torregrosa, Increasing the convergence order of an iterative method for nonlinear systems, Appl. Math. Lett., 25 (2012), 2369–2374.I. K. Argyros and A. A. Magreñán, A study on the local convergence and dynamics of Chebyshev- Halley-type methods free from second derivative, Numer. Algorithms71 (2016), 1–23.M. Grau-Sánchez, Á Grau, asnd M. Noguera, Frozen divided difference scheme for solving systems of nonlinear equations, J. Comput. Appl. Math., 235 (2011), 1739–1743.M. Grau-Sánchez, M. Noguera, and S. Amat, On the approximation of derivatives using divided difference operators preserving the local convergence order of iterative methods, J. Comput. Appl. Math., 237 (2013), 363–372

Supermarket Characteristics and Operating Costs in Low-Income Areas

Research on low-income household food costs shows that the poor often have limited shopping opportunities and pay slightly higher prices for food. It is often hypothesized that higher prices are due, at least in part, to higher operating costs for stores that serve low-income households. This paper reports on research assessing how supermarket characteristics and operating costs differ with the percentage of sales derived from food stamp redemptions. Stores with a high percentage of revenues from food stamps generally offer fewer services that save time and add convenience for shoppers. They also offer a different mix of products, with a greater portion of sales coming from dry groceries and meat. Stores serving low-income shoppers use relatively little labor per 1,000 square feet of selling area. This helps keep labor costs as a percent of sales low, but gross margins for stores serving low-income consumers are also relatively low. Results from a cost function analysis indicate that stores serving low-income consumers are relatively well adapted to their market environment. But larger, more progressive supermarkets operated by major chains could provide significant competition for the typical store serving the urban poor. Overall, our results do not provide strong support for the hypothesis that it costs more to operate supermarkets that serve low-income consumers

Dimerization of visinin-like protein 1 is regulated by oxidative stress and calcium and is a pathological hallmark of amyotrophic lateral sclerosis

AbstractRedox control of proteins that form disulfide bonds upon oxidative challenge is an emerging topic in the physiological and pathophysiological regulation of protein function. We have investigated the role of the neuronal calcium sensor protein visinin-like protein 1 (VILIP-1) as a novel redox sensor in a cellular system. We have found oxidative stress to trigger dimerization of VILIP-1 within a cellular environment and identified thioredoxin reductase as responsible for facilitating the remonomerization of the dimeric protein. Dimerization is modulated by calcium and not dependent on the myristoylation of VILIP-1. Furthermore, we show by site-directed mutagenesis that dimerization is exclusively mediated by Cys187. As a functional consequence, VILIP-1 dimerization modulates the sensitivity of cells to an oxidative challenge. We have investigated whether dimerization of VILIP-1 occurs in two different animal models of amyotrophic lateral sclerosis (ALS) and detected soluble VILIP-1 dimers to be significantly enriched in the spinal cord from phenotypic disease onset onwards. Moreover, VILIP-1 is part of the ALS-specific protein aggregates. We show for the first time that the C-terminus of VILIP-1, containing Cys187, might represent a novel redox-sensitive motif and that VILIP-1 dimerization and aggregation are hallmarks of ALS. This suggests that VILIP-1 dimers play a functional role in integrating the cytosolic calcium concentration and the oxidative status of the cell. Furthermore, a loss of VILIP-1 function owing to protein aggregation in ALS could be relevant in the pathophysiology of the disease

Lipid and protein content profiling of isolated native autophagic vesicles

Autophagy is responsible for clearance of an extensive portfolio of cargoes, which are sequestered into vesicles, called autophagosomes, and are delivered to lysosomes for degradation. The pathway is highly dynamic and responsive to several stress conditions. However, the phospholipid composition and protein contents of human autophagosomes under changing autophagy rates are elusive so far. Here, we introduce an antibody-based FACS-mediated approach for the isolation of native autophagic vesicles and ensured the quality of the preparations. Employing quantitative lipidomics, we analyze phospholipids present within human autophagic vesicles purified upon basal autophagy, starvation, and proteasome inhibition. Importantly, besides phosphoglycerides, we identify sphingomyelin within autophagic vesicles and show that the phospholipid composition is unaffected by the different conditions. Employing quantitative proteomics, we obtain cargo profiles of autophagic vesicles isolated upon the different treatment paradigms. Interestingly, starvation shows only subtle effects, while proteasome inhibition results in the enhanced presence of ubiquitin-proteasome pathway factors within autophagic vesicles. Thus, here we present a powerful method for the isolation of native autophagic vesicles, which enabled profound phospholipid and cargo analyses

Anatomy of a Dansgaard-Oeschger warming transition: High-resolution analysis of the North Greenland Ice Core Project ice core

Large and abrupt temperature oscillations during the last glacial period, known as Dansgaard‐Oeschger (DO) events, are clearly observed in the Greenland ice core record. Here we present a new high‐resolution chemical (2 mm) and stable isotope (20 mm) record from the North Greenland Ice Core Project (NGRIP) ice core at the onset of one of the most prominent DO events of the last glacial, DO‐8, observed ∼38,000 years ago. The unique, subannual‐resolution NGRIP record provides a true sequence of change during a DO warming with detailed annual layer counting of very high depth resolution geochemical measurements used to determine the exact duration of the transition. The continental ions, indicative of long‐range atmospheric loading and dustiness from East Asia, are the first to change, followed by the snow accumulation, the moisture source conditions, and finally the atmospheric temperature in Greenland. The sequence of events shows that atmospheric and oceanic source and circulation changes preceded the DO warming by several years

Intermittent existence of a southern Californian upwelling cell during submillennial climate change of the last 60 kyr

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95021/1/palo1108.pd

Estrogen Prevents Oxidative Damage to the Mitochondria in Friedreich's Ataxia Skin Fibroblasts

Estrogen and estrogen-related compounds have been shown to have very potent cytoprotective properties in a wide range of disease models, including an in vitro model of Friedreich's ataxia (FRDA). This study describes a potential estrogen receptor (ER)-independent mechanism by which estrogens act to protect human FRDA skin fibroblasts from a BSO-induced oxidative insult resulting from inhibition of de novo glutathione (GSH) synthesis. We demonstrate that phenolic estrogens, independent of any known ER, are able to prevent lipid peroxidation and mitochondrial membrane potential (ΔΨm) collapse, maintain ATP at near control levels, increase oxidative phosphorylation and maintain activity of aconitase. Estrogens did not, however, prevent BSO from depleting GSH or induce an increased expression level of GSH. The cytoprotective effects of estrogen appear to be due to a direct overall reduction in oxidative damage to the mitochondria, enabling the FRDA fibroblast mitochondria to generate sufficient ATP for energy requirements and better survive oxidative stress. These data support the hypothesis that phenol ring containing estrogens are possible candidate drugs for the delay and/or prevention of FRDA symptoms

Principles and criteria in the development and optimization of topical therapeutic products : Sponsored by the American Association of Pharmaceutical Scientists (AAPS) and U.S. Food and Drug Administration (FDA)

This report derived from the dermatological workshop discusses the problems and issues in the development and optimization of topical therapeutic drug products. It provides a clear understanding and differentiation between transdermal and dermal products. The report also discusses the bioavailability/bioequivalence issues for topical therapeutic products.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30099/1/0000471.pd