61 research outputs found
Driven polymer translocation through nanopores: slow versus fast dynamics
We investigate the dynamics of polymer translocation through nanopores under
external driving by 3D Langevin Dynamics simulations, focusing on the scaling
of the average translocation time versus the length of the polymer,
. For slow translocation, i.e., under low driving force
and/or high friction, we find where
denotes the Flory exponent. In contrast, is observed for
fast translocation due to the highly deformed chain conformation on the trans
side, reflecting a pronounced non-equilibrium situation. The dependence of the
translocation time on the driving force is given by and
for slow and fast translocation, respectively. These
results clarify the controversy on the magnitude of the scaling exponent
for driven translocation.Comment: 6 pages, 7 figures, to appear in EPL (Europhysics Letters
Polymer translocation out of confined environments
We consider the dynamics of polymer translocation out of confined
environments. Analytic scaling arguments lead to the prediction that the
translocation time scales like for translocation out of a planar
confinement between two walls with separation into a 3D environment, and
for translocation out of two strips with separation
into a 2D environment. Here, is the chain length, and
are the Flory exponents in 3D and 2D, and is the scaling exponent of
translocation velocity with , whose value for the present choice of
parameters is based on Langevin dynamics simulations. These
scaling exponents improve on earlier predictions.Comment: 5 pages, 5 figures. To appear in Phys. Rev.
Understanding the role of crystallographic shear on the electrochemical behavior of niobium oxyfluorides
The effects of shear planes in perovskite materials have been studied in order to identify their role in the electrochemical behavior of Li⁺ intercalation hosts. These planes modulate the structural stability and ionic transport pathways and therefore play an intimate role in the characteristics and performance of shear compounds. Herein, two Nb-based compounds, NbO₂F and Nb₃O₇F, were chosen as representative perovskite and shear derivatives respectively to investigate the role of crystallographic shear. A series of operando measurements, including X-ray diffraction and X-ray absorption spectroscopy, in conjunction with structural analysis, Raman spectroscopy, and detailed electrochemical studies identified the effect of shear planes. It was found that shear planes led to increased structural stability during Li⁺ (de)intercalation with shear layers being maintained, while perovskite layers were seen to degrade rapidly. However, disordering in the shear plane stacking introduced during delithiation ultimately led to poor capacity retention despite structural maintenance as Li⁺ diffusion channels are disrupted
Global Panopticism: States, Corporations, and the Governance Effects of Monitoring Regimes
Catching-up and falling behind knowledge spillover from American to German machine tool makers
In our days, German machine tool makers accuse their Chinese competitors of violating patent rights and illegally imitating German technology. A century ago, however, German machine tool makers used exactly the same methods to imitate American technology. To understand the dynamics of this catching-up process we use patent statistics to analyze firms? activities between 1877 and 1932. We show that German machine tool makers successfully deployed imitating and counterfeiting activities in the late 19th century and the 1920s to catchup to their American competitors. The German administration supported this strategy by stipulating a patent law that discriminated against foreign patent holders and probably also by delaying the granting of patents to foreign applicants. Parallel to the growing international competitiveness of German firms, however, the willingness to guarantee intellectual property rights of foreigners was also increasing because German firms had now to fear retaliatory measures in their own export markets when violating foreign property rights within Germany
Transnational Comparisons: Theory and Practice of Comparative Law as a Critique of Global Governance
Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world
Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic.
Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality.
Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States.
Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis.
Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection
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