Overcharging: The Crucial Role of Excluded Volume

In this Letter we investigate the mechanism for overcharging of a single spherical colloid in the presence of aqueous salts within the framework of the primitive model by molecular dynamics (MD) simulations as well as integral-equation theory. We find that the occurrence and strength of overcharging strongly depends on the salt-ion size, and the available volume in the fluid. To understand the role of the excluded volume of the microions, we first consider an uncharged system. For a fixed bulk concentration we find that upon increasing the fluid particle size one strongly increases the local concentration nearby the colloidal surface and that the particles become laterally ordered. For a charged system the first surface layer is built up predominantly by strongly correlated counterions. We argue that this a key mechanism to produce overcharging with a low electrostatic coupling, and as a more practical consequence, to account for charge inversion with monovalent aqueous salt ions.Comment: 7 pages, 3 figs (4 EPS files). To appear in Europhysics Letter

The electrical double layer for a fully asymmetric electrolyte around a spherical colloid: an integral equation study

The hypernetted chain/mean spherical approximation (HNC/MSA) integral equation is obtained and solved numerically for a totally asymmetric primitive model electrolyte around a spherical macroparticle. The ensuing radial distribution functions show a very good agreement when compared to our Monte Carlo and molecular dynamics simulations for spherical geometry and with respect to previous anisotropic reference HNC calculations in the planar limit. We report an analysis of the potential vs charge relationship, radial distribution functions, mean electrostatic potential and cumulative reduced charge for representative cases of 1:1 and 2:2 salts with a size asymmetry ratio of 2. Our results are collated with those of the Modified Gouy-Chapman (MGC) and unequal radius Modified Gouy-Chapman (URMGC) theories and with those of HNC/MSA in the restricted primitive model (RPM) to assess the importance of size asymmetry effects. One of the most striking characteristics found is that,\textit{contrary to the general belief}, away from the point of zero charge the properties of an asymmetric electrical double layer (EDL) are not those corresponding to a symmetric electrolyte with the size and charge of the counterion, i.e. \textit{counterions do not always dominate}. This behavior suggests the existence of a new phenomenology in the EDL that genuinely belongs to a more realistic size-asymmetric model where steric correlations are taken into account consistently. Such novel features can not be described by traditional mean field theories like MGC, URMGC or even by enhanced formalisms, like HNC/MSA, if they are based on the RPM.Comment: 29 pages, 13 figure

Foreign Direct Investment For Developing Financing: Teaching Market-Related Aspects Through Cases

This article presents two cases that have been used to supplement the teaching of how market-related aspects impact decisions, policies and tasks associated with attracting foreign direct investment into emerging markets and developing economies. The authors share their experiences in workshops and in the classroom and provide discussion strategies and teaching notes for each case

Processing Popup Ads and Print Ads: A Comparative Study between American, Brazilian, and Argentinean Consumers

As more and more companies become global business entities, it will be important to find out how traditional consumer behavior processes and relationships work in different countries. A comparison of the processing of a traditional print ad and popup ad are compared within and between the United States, Brazil, and Argentina. Very little research exists regarding traditional consumer behavior and advertising model outcomes in Brazil and Argentina. Since these two Latin American countries have become large economic powers in the global economy, it is important to study how these countries’ consumers react to existing models of consumption and advertising. Could there be differences due to some cultural influences? Cross-cultural experimental research is a good first step to try and develop some answers so companies can correctly use existing or new marketing strategies to successfully sell their products in these countries. The experiment followed a two (media: print or web) by two (argument quality: strong or weak) by two (involvement: high or weak), between-subject factorial design. Subjects participated in groups that ranged in size from 23 to 30. Target ads included a brand of personal computer and orange soda that were not familiar to the subjects tested. Dependent variables included attitude- toward- the- ad, attitude-toward- the- brand, purchase intention, and attitude-toward-the-ad- claim. Preliminary results indicate American subjects have a higher Aad for web ads than for print ads and a greater Abrand for web ads than for print ads. But this is not the case for their Brazilian and Argentinean counterparts. The ultimate goal of course, is to aide marketers in understanding their customers and to help them sell more products. This experiment may help marketers determine where to put their promotional dollar allocations in several countries or not and in what advertising form

Critical Analysis of the Results of the CPA Exam for the Second Decade of This Century: Empirical Evidence From Puerto Rico

The research for the first time examines the performance of candidates for the uniform Certified Public Accountant exam in the Hispanic jurisdiction of Puerto Rico from 2010 to 2019. The study presents an innovative method of classifying the quality of accounting programs, based on the performance of their alumni on the exam, according to their pass rate, average score, and their contribution to the total number of new CPA’s admitted to the profession. Candidates from public institutions perform better than candidates from private institutions. The research provides methodology that can be replicated in any profession that requires a professional license

Solidarity (Solidarność) at Forty: Memories and Influences on Contemporary Poland - Does Solidarity Still Matter?

This paper is dedicated to the memory of Brother Leo V. Ryan, C.S.V., who passed away in 2016. Abstract Part I of the paper is a retrospective on the origins of the Solidarity Movement in Poland and the economic program it introduced after its assumption of power in 1989. Part II outlines various challenges faced by Polish society in light of current political configurations and discusses Solidarity’s contemporary relevance on the political and economic calculus of Poland. This retrospective is based on more than thirty-five years of research and analysis on the Polish economic and political scenes. Keywords: Poland, Polish Economy, Solidarity Movement, JUST REMEMBER: STALIN HIMSELF WAS REPORTED TO HAVE STATED THAT “SOCIALISM WOULD FIT POLAND LIKE A SADDLE WOULD FIT A COW.” DOI: 10.7176/EJBM/11-23-12 Publication date: August 31st 201

Insulator phases of Bose-Fermi mixtures induced by next-neighbor interactions between fermions

We study a one-dimensional mixture of two-color fermions and scalar bosons at the hard-core limit, focusing on the effect that the next-neighbor interaction between fermions has on the zero-temperature ground state of the system for different fillings of each carrier. Exploring the parameters of the problem, we observed that the non-local interaction modifies the well-known mixed and spin-selective Mott insulators, and we also found the emergence of three unusual insulating states with peculiar charge density wave orderings, a fully out-of-phase density of carriers for bosonic half-filling, an insulator with the same bosonic and fermionic fillings, and a different spin-selective insulator where the bosonic filling matches the density of one kind of fermion. Modern cold-atom setups correspond to the ideal experimental setting where these incommensurable insulators can be observed.Comment: 11 pages, 9 figures. Comments are welcom

A Primer On International Environmental Law: Sustainability As A Principle Of International Law And Custom

International environmental law draws from two important sources: international treaties and conventions\u27 and customary international law

The Supreme Court as the Grand Mediator in Social Regulation of the Media - De Gustibus Non Disputandum Est: Or Are They

This article presents a study of administrative and statutory schemes designed to regulate various aspects of the media in considering broad questions of indecency, obscenity, and societal and parental controls over content in various forms of media broadcasting. The article then provides an important historical back-drop by referencing Burstyn v. Wilson (a 1950s case involving an alleged secular sacrilege ) and Pacifica Foundation (the George Carlin Filthy Words monologue case). It then turns to a discussion of the litigation and controversy spurred by passage of the Communications Decency Act of 1996 and the Child Online Protection Act of 1998 as the focus of congressional attention turned to regulating the Internet. In this context, the article discusses Reno v. ACLU and American Library Association v. United States, two cases which provided direct challenges to Congressional regulatory responses. This article concludes by noting important international implications of the attempts to place restrictions on the Internet, and offers several tentative conclusions by bringing to the forefront the debate on the use of filtering technology designed to provide controls and supervision over this new media

Vortices on demand in multicomponent Bose-Einstein condensates

We present a simple mechanism to produce vortices at any desired spatial locations in harmonically trapped Bose-Einstein condensates (BEC) with multicomponent spin states coupled to external transverse and axial magnetic fields. The vortices appear at the spatial points where the spin-transverse field interaction vanishes and, depending on the multipolar magnetic field order, the vortices can acquire different predictable topological charges. We explicitly demonstrate our findings, both numerically and analytically, by analyzing a 2D BEC via the Gross-Pitaevskii equation for atomic systems with either two or three internal states. We further show that, by an spontaneous symmetry breaking mechanism, vortices can appear in any spin component, unless symmetry is externally broken at the outset by an axial field. We suggest that this scenario may be tested using an ultracold gas of $^{87}$Rb occupying all three $F = 1$ states in an optical trap.Comment: 11 pages, 9 figures, (Accepted in PRA