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Novak N.,Bronx Community College
Electronic Notes in Theoretical Computer Science | Year: 2015

Knowledge, belief, and evidence are fundamental notions which appear in a wide range of areas. Over the last decade epistemic reasoning with justifications has broadened even more the scope of applications of epistemic logic as agents gained the ability to not only reason about epistemic states of knowledge and belief of agents, but also to track their justifications and to sort those which are pertinent to given facts and sufficient for epistemic conclusions. This paper extends realization algorithm for S4-to-LP case to S4Jn-to-S4nLP case. It converts cut-free derivations in S4Jn into derivations in the corresponding Justification Logic S4nLP where witnesses of knowledge, the justification terms, are recovered for all instances of justified common knowledge. The algorithm was implemented in the MetaPRL framework and was tested on several well-known epistemic puzzles, such as Muddy Children, Surprise Examination Paradox, etc. © 2015 The Author. Published by Elsevier B.V.


Knight J.C.,University of Texas at Austin | Therese S.,University of Texas at Austin | Therese S.,Bronx Community College | Manthiram A.,University of Texas at Austin
ACS Applied Materials and Interfaces | Year: 2015

There is immense interest to develop Mg-ion batteries, but finding suitable cathode materials has been a challenge. The spinel structure has many advantages for ion insertion and has been successfully used in Li-ion batteries. We present here findings on the attempts to extract Mg from MgMn2O4-based spinels with acid (H2SO4) and with NO2BF4. The acid treatment was able to fully remove all Mg from MgMn2O4 by following a mechanism involving the disproportionation of Mn3+, and the extraction rate decreased with increasing cation disorder. Samples with additional Mg2+ ions in the octahedral sites (e.g., Mg1.1Mn1.9O4 and Mg1.5Mn1.5O4) also exhibit complete or near complete demagnesiation due to an additional mechanism involving ion exchange of Mg2+ by H+, but no Mg could be extracted from MgMnAlO4 due to the disruption of Mn-Mn interaction/contact across shared octahedral edges. In contrast, no Mg could be extracted with the oxidizing agent NO2BF4 from MgMn2O4 or Mg1.5Mn1.5O4 as the electrostatic repulsion between the divalent Mg2+ ions prevents Mg2+ diffusion through the 16c octahedral sites, unlike Li+ diffusion, suggesting that spinels may not serve as potential hosts for Mg-ion batteries. The ability to extract Mg with acid in contrast to that with NO2BF4 is attributed to Mn dissolution from the lattice and the consequent reduction in electrostatic repulsion. The findings could provide insights toward the design of Mg hosts for Mg-ion batteries. © 2015 American Chemical Society.


Miko B.A.,Columbia University | Miko B.A.,The Interdisciplinary Center | Cohen B.,The Interdisciplinary Center | Conway L.,The Interdisciplinary Center | And 3 more authors.
American Journal of Infection Control | Year: 2012

Background: Although several studies have characterized the hygiene habits of college students, few have assessed the determinants underlying such behaviors. Objectives: Our study sought to describe students' knowledge, practices, and beliefs about hygiene and determine whether there is an association between reported behaviors and frequency of illness. Methods: A sample of 299 undergraduate students completed a questionnaire assessing demographics, personal and household hygiene behaviors, beliefs and knowledge about hygiene, and general health status. Results: Variation in reported hygiene habits was noted across several demographic factors. Women reported "always" washing their hands after using the toilet (87.1%) more than men (65.3%, P =.001). Similarly, freshmen reported such behavior (80.4%) more than sophomores (71.9%), juniors (67.7%), or seniors (50%, P =.011). Whereas 96.6% of participants thought that handwashing was either "very important" or "somewhat important" for preventing disease, smaller proportions thought it could prevent upper respiratory infections (85.1%) or gastroenteritis (48.3%), specifically. There was no significant relationship between reported behaviors and self-reported health status. Conclusion: The hygiene habits of college students may be motivated by perceptions of socially acceptable behavior rather than scientific knowledge. Interventions targeting the social norms of incoming and continuing students may be effective in improving hygiene determinants and ultimately hygiene practices. Copyright © 2012 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.


Martinez M.R.,Bronx Community College | Tar M.,Bronx NY | Han G.,Yeshiva University | Friedman A.J.,Yeshiva University | And 3 more authors.
Journal of Infectious Diseases | Year: 2010

Candida species are a major cause of catheter infections. Using a central venous catheter Candida albicans biofilm model, we demonstrated that chitosan, a polymer isolated from crustacean exoskeletons, inhibits candidal biofilm formation in vivo. Furthermore, chitosan statistically significantly decreased both the metabolic activity of the biofilms and the cell viability of C. albicans and Candida parapsilosis biofilms in vitro. In addition, confocal and scanning electron microscopic examination demonstrated that chitosan penetrates candidal biofilms and damages fungal cells. Importantly, the concentrations of chitosan that were used to evaluate fungal biofilm susceptibility were not toxic to human endothelial cells. Chitosan should be considered for the prevention or treatment of fungal biofilms on central venous catheters and perhaps other medical devices. © 2010 by the Infectious Diseases Society of America. All rights reserved.


Knight J.C.,University of Texas at Austin | Therese S.,University of Texas at Austin | Therese S.,Bronx Community College | Manthiram A.,University of Texas at Austin
Journal of Materials Chemistry A | Year: 2015

With an aim to increase the energy density compared to current Li-ion batteries, there is immense interest in rechargeable batteries with multivalent cations, such as Mg2+ and Zn2+, as they could provide higher charge storage capacity. α-MnO2 has been investigated as a cathode for Zn-ion batteries, but other structures could be explored. Accordingly, this study investigates the chemical extraction of Zn from the spinel compositions ZnMn2-xNixO4 (x = 0, 0.5, and 1) using H2SO4 and NO2BF4. Acid treatment is able to extract Zn from the structure through a Mn3+ disproportionation reaction that is dependent on the Mn3+ content. Zn extraction decreases with increasing Ni content due to the decrease in Mn3+ content; in fact, ZnMnNiO4 does not lose any Zn upon acid treatment because all of the Mn ions are in the 4+ state. Treatment with NO2BF4, however, is unable to extract any Zn from the samples, unlike in the analogous LiMn2O4 spinel. This is believed to be due to the high electrostatic repulsion that Zn2+ ions would feel from other Zn2+ ions in neighboring tetrahedral sites as they have to diffuse through the unoccupied octahedral sites in the spinel lattice, and Zn2+ does not prefer octahedral sites. Because NO2BF4 more closely approximates the extraction mechanism experienced in a Zn-ion cell, it appears that the ideal spinel structure is not suitable as a Zn-ion battery cathode unless synthesis conditions or additional treatments were used to create vacancies in the structure that allows for easier Zn-ion diffusion without much electrostatic repulsion. © The Royal Society of Chemistry.

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