1,003 research outputs found
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 Rb occupying all
three states in an optical trap.Comment: 11 pages, 9 figures, (Accepted in PRA
- …