468 research outputs found
Cavity-ligand binding in a simple two-dimensional water model
By means of Monte Carlo computer simulations in the isothermal-isobaric
ensemble, we investigated the interaction of a hydrophobic ligand with the
hydrophobic surfaces of various curvatures (planar, convex and concave). A
simple two-dimensional model of water, hydrophobic ligand and surface was used.
Hydration/dehidration phenomena concerning water molecules confined close to
the molecular surface were investigated. A notable dewetting of the hydrophobic
surfaces was observed together with the reorientation of the water molecules
close to the surface. The hydrogen bonding network was formed to accommodate
cavities next to the surfaces as well as beyond the first hydration shell. The
effects were most strongly pronounced in the case of concave surfaces having
large curvature. This simplified model can be further used to evaluate the
thermodynamic fingerprint of the docking of hydrophobic ligands.Comment: 6 pages, 5 figure
Application of Replica Ornstein-Zernike equations in studies of the adsorption of electrolyte mixtures in disordered matrices of charged particles
The Replica Ornstein-Zernike (ROZ) equations were used to study the adsorption of ions from electrolyte mixtures.
The adsorbent was represented as a quenched primitive model +1:-1 size symmetric electrolyte, while
the mobile particles were ions differing in charge and/or size. The ROZ equations in hypernetted-chain (HNC)
approximation were tested against new Monte Carlo results in the grand canonical ensemble; good agreement
between the two methods was obtained. The ROZ/HNC theory was then used to study the exclusion
coefficients as a function of size and/or charge asymmetry of the annealed ions.Реплiчне рiвняння Орнштейна-Цернiке (РОЦ) застосоване для вивчення адсорбцiї iонiв iз сумiшей
електролiтiв. Адсорбент розглядається у виглядi замороженої примiтивної +1:-1 моделi розмiрно
симетричного електролiту, тодi як рухомi частинки – це iони, що вiдрiзняються зарядом та/або роз-
мiрами. Данi, що отриманi з рiвняння РОЦ у гiперланцюжковому наближеннi (ГЛН), порiвняно з но-
вими результатами Монте-Карло моделювання у великому канонiчному ансамблi i виявлено хороше
узгодження мiж обома методами. Теорiю РОЦ/ГЛН далi було використано для вивчення коефiцiєнтiв
виключення, в залежностi вiд параметрiв розмiрної та/або зарядової асиметрiй нерухомих iонiв
Modeling Amphiphilic Solutes in a Jagla Solvent
Methanol is an amphiphilic solute whose aqueous solutions exhibit distinctive
physical properties. The volume change upon mixing, for example, is negative
across the entire composition range, indicating strong association. We explore
the corresponding behavior of a Jagla solvent, which has been previously shown
to exhibit many of the anomalous properties of water. We consider two models of
an amphiphilic solute: (i) a "dimer" model, which consists of one hydrophobic
hard sphere linked to a Jagla particle with a permanent bond, and (ii) a
"monomer" model, which is a limiting case of the dimer, formed by
concentrically overlapping a hard sphere and a Jagla particle. Using discrete
molecular dynamics, we calculate the thermodynamic properties of the resulting
solutions. We systematically vary the set of parameters of the dimer and
monomer models and find that one can readily reproduce the experimental
behavior of the excess volume of the methanolwater system as a function of
methanol volume fraction. We compare the pressure and temperature dependence of
the excess volume and the excess enthalpy of both models with experimental data
on methanol-water solutions and find qualitative agreement in most cases. We
also investigate the solute effect on the temperature of maximum density and
find that the effect of concentration isorders of magnitude stronger than
measured experimentally
Disclosing physician ratings: performance effects and the difficulty of altering rating consensus
I examine effects of a health care system's policy to publicly disclose patient ratings of its physicians. I find evidence that this policy leads to performance improvement by the disclosed, subjective ratings and also by undisclosed, objective measures of quality. These effects are consistent with multitasking theory, in that physicians respond to the disclosure by providing more of a shared input—time with patients—that benefits performance by ratings and underlying quality. I also find, as predicted by information cascade theory, that the ratings become jammed to some degree near initially disclosed values. Specifically, raters observe the pattern of initial ratings and follow suit by providing similar ratings. Finally, I find evidence that physicians anticipate rating jamming and so concentrate their effort on earlier performance in order to set a pattern of high ratings that later ratings follow. These results demonstrate that the disclosure of subjective ratings can benefit performance broadly but can also shift effort toward earlier performance
Influence of solvent granularity on the effective interaction between charged colloidal suspensions
We study the effect of solvent granularity on the effective force between two
charged colloidal particles by computer simulations of the primitive model of
strongly asymmetric electrolytes with an explicitly added hard sphere solvent.
Apart from molecular oscillating forces for nearly touching colloids which
arise from solvent and counterion layering, the counterions are attracted
towards the colloidal surfaces by solvent depletion providing a simple
statistical description of hydration. This, in turn, has an important influence
on the effective forces for larger distances which are considerably reduced as
compared to the prediction based on the primitive model. When these forces are
repulsive, the long-distance behaviour can be described by an effective Yukawa
pair potential with a solvent-renormalized charge. As a function of colloidal
volume fraction and added salt concentration, this solvent-renormalized charge
behaves qualitatively similar to that obtained via the Poisson-Boltzmann cell
model but there are quantitative differences. For divalent counterions and
nano-sized colloids, on the other hand, the hydration may lead to overscreened
colloids with mutual attraction while the primitive model yields repulsive
forces. All these new effects can be accounted for through a solvent-averaged
primitive model (SPM) which is obtained from the full model by integrating out
the solvent degrees of freedom. The SPM was used to access larger colloidal
particles without simulating the solvent explicitly.Comment: 14 pages, 16 craphic
Tuberculosis incidence in foreign-born people residing in European countries in 2020.
BackgroundEuropean-specific policies for tuberculosis (TB) elimination require identification of key populations that benefit from TB screening.AimWe aimed to identify groups of foreign-born individuals residing in European countries that benefit most from targeted TB prevention screening.MethodsThe Tuberculosis Network European Trials group collected, by cross-sectional survey, numbers of foreign-born TB patients residing in European Union (EU) countries, Iceland, Norway, Switzerland and the United Kingdom (UK) in 2020 from the 10 highest ranked countries of origin in terms of TB cases in each country of residence. Tuberculosis incidence rates (IRs) in countries of residence were compared with countries of origin.ResultsData on 9,116 foreign-born TB patients in 30 countries of residence were collected. Main countries of origin were Eritrea, India, Pakistan, Morocco, Romania and Somalia. Tuberculosis IRs were highest in patients of Eritrean and Somali origin in Greece and Malta (both > 1,000/100,000) and lowest among Ukrainian patients in Poland (3.6/100,000). They were mainly lower in countries of residence than countries of origin. However, IRs among Eritreans and Somalis in Greece and Malta were five times higher than in Eritrea and Somalia. Similarly, IRs among Eritreans in Germany, the Netherlands and the UK were four times higher than in Eritrea.ConclusionsCountry of origin TB IR is an insufficient indicator when targeting foreign-born populations for active case finding or TB prevention policies in the countries covered here. Elimination strategies should be informed by regularly collected country-specific data to address rapidly changing epidemiology and associated risks
Applying Benford’s law to detect accounting data manipulation in the banking industry
We utilise Benford’s Law to test if balance sheet and income statement data broadly used to assess bank soundness were manipulated prior to and also during the global financial crisis. We find that all banks resort to loan loss provisions to manipulate earnings and income upwards. Distressed institutions that have stronger incentives to conceal their financial difficulties resort additionally to manipulating loan loss allowances and non-performing loans downwards. Moreover, manipulation is magnified during the crisis and expands to encompass regulatory capital
Where do firms manage earnings?
Despite decades of research on how, why, and when companies manage earnings, there is a paucity of evidence about the geographic location of earnings management within multinational firms. In this study, we examine where companies manage earnings using a sample of 2,067 U.S. multinational firms from 1994 to 2009. We predict and find that firms with extensive foreign operations in weak rule of law countries have more foreign earnings management than companies with subsidiaries in locations where the rule of law is strong. We also find some evidence that profitable firms with extensive tax haven subsidiaries manage earnings more than other firms and that the earnings management is concentrated in foreign income. Apart from these results, we find that most earnings management takes place in domestic income, not foreign income.Arthur Andersen (Firm) (Arthur Andersen Faculty Fund
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