17,357 research outputs found
Loser-Paysâor Whose âFaultâ is it Anyway: A Response to Hensler-Roweâs âBeyond âIt Just Ainât Worth itââ
The aim of this study is to evaluate the efficiency of public transport operations undertaken in Swedish counties by the Public Transport Authorities (PTA), taking into account the substantial differences in operating conditions between counties. The analysis will be performed using Stochastic Frontier Analysis (SFA) with annual data from 1986 to 2009 for 26 Swedish counties. The analysis shows how the efficiency of the individual counties has changed over time. The results are used to provide a ranking (in terms of efficiency) of the Swedish public transport authorities that can provide a basis for benchmarking. It is concluded that the efficiency of the public transport providers in all counties fell during the observed time period. Defining cost efficiency as the ratio of minimum cost to observed cost, the overall (average) cost efficiency for the industry fell from 85.7% in the eighties to 60.4% for the period from 2000 to 2009. Possible explanations for the development include increased emphasis on route density as well as higher environmental and safety requirements
Polymer-stabilized sialylated nanoparticles : synthesis, optimization, and differential binding to influenza hemagglutinins
During influenza infection, hemagglutinins (HAs) on the viral surface bind to sialic acids on the host cell's surface. While all HAs bind sialic acids, human influenza targets terminal α2,6 sialic acids and avian influenza targets α2,3 sialic acids. For interspecies transmission (zoonosis), HA must mutate to adapt to these differences. Here, multivalent gold nanoparticles bearing either α2,6- or α2,3-sialyllactosamine have been developed to interrogate a panel of HAs from pathogenic human, low pathogenic avian, and other species' influenza. This method exploits the benefits of multivalent glycan presentation compared to monovalent presentation to increase affinity and investigate how multivalency affects selectivity. Using a library-orientated approach, parameters including polymer coating and core diameter were optimized for maximal binding and specificity were probed using galactosylated particles and a panel of biophysical techniques [ultraviolet-visible spectroscopy, dynamic light scattering, and biolayer interferometry]. The optimized particles were then functionalized with sialyllactosamine and their binding analyzed against a panel of HAs derived from pathogenic influenza strains including low pathogenic avian strains. This showed significant specificity crossover, which is not observed in monovalent formats, with binding of avian HAs to human sialic acids and in agreement with alternate assay formats. These results demonstrate that precise multivalent presentation is essential to dissect the interactions of HAs and may aid the discovery of tools for disease and zoonosis transmission
Relaxation time of the topological T1 process in a two-dimensional foam
The elementary topological T1 process in a two-dimensional foam corresponds
to the "flip" of one soap film with respect to the geometrical constraints.
From a mechanical point of view, this T1 process is an elementary relaxation
process through which the entire structure of an out-of-equilibrium foam
evolves. The dynamics of this elementary relaxation process has been poorly
investigated and is generally neglected during simulations of foams. We study
both experimentally and theoretically the T1 dynamics in a dry two-dimensional
foam. We show that the dynamics is controlled by the surface viscoelastic
properties of the soap films (surface shear plus dilatational viscosity, ms+k,
and Gibbs elasticity e), and is independent of the shear viscosity of the bulk
liquid. Moreover, our approach illustrates that the dynamics of T1 relaxation
process provides a convenient tool for measuring the surface rheological
properties: we obtained e = 32+/-8 mN/m and ms+k = 1.3+/-0.7 mPa.m.s for SDS,
and e = 65+/-12 mN/m and ms+k = 31+/-12 mPa.m.s for BSA, in good agreement with
values reported in the literature
Synaptic metaplasticity underlies tetanic potentiation in Lymnaea: a novel paradigm
We present a mathematical model which explains and interprets a novel form of
short-term potentiation, which was found to be use-, but not time-dependent, in
experiments done on Lymnaea neurons. The high degree of potentiation is
explained using a model of synaptic metaplasticity, while the use-dependence
(which is critically reliant on the presence of kinase in the experiment) is
explained using a model of a stochastic and bistable biological switch.Comment: 12 pages, 7 figures, to appear in PLoS One (2013
Carbon-rich planet formation in a solar composition disk
The C--to--O ratio is a crucial determinant of the chemical properties of
planets. The recent observation of WASP 12b, a giant planet with a C/O value
larger than that estimated for its host star, poses a conundrum for
understanding the origin of this elemental ratio in any given planetary system.
In this paper, we propose a mechanism for enhancing the value of C/O in the
disk through the transport and distribution of volatiles. We construct a model
that computes the abundances of major C and O bearing volatiles under the
influence of gas drag, sublimation, vapor diffusion, condensation and
coagulation in a multi--iceline 1+1D protoplanetary disk. We find a gradual
depletion in water and carbon monoxide vapors inside the water's iceline with
carbon monoxide depleting slower than water. This effect increases the gaseous
C/O and decreases the C/H ratio in this region to values similar to those found
in WASP 12b's day side atmosphere. Giant planets whose envelopes were accreted
inside the water's iceline should then display C/O values larger than those of
their parent stars, making them members of the class of so-called ``carbon-rich
planets''.Comment: 8 pages, 4 figures, accepted for publication Ap
Corporate Governance in the Financial Sector of Pakistan
La Porta et al. (1998) assign Pakistan, a common-law country, the maximum score of 5 for their anti-director rights index. Pakistan should therefore be a country with good investor protection attracting large amounts of investments. However, the reality could not be more different. Pakistan has been lagging behind other, comparable Asian economies in terms of incoming foreign direct investment as well as GDP-per-capita growth. This paper focuses on the Pakistani banking sector. The paper analyses the banks ownership and control structure. It finds that Pakistan has its own idiosyncrasies, which are difficult to associate with La Porta et al.s characterisation of corporate governance and investor protection in common-law countries. The paper also reviews the recent reforms of corporate governance.Corporate governance, corporate control, Banks, Pakistan, Emerging Markets, investor protection
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