11,886 research outputs found
High altitude gust acceleration environment as experienced by a supersonic airplane
High altitude turbulence experienced at supersonic speeds is described in terms of gust accelerations measured on the YF-12A airplane. The data were obtained during 90 flights at altitudes above 12.2 kilometers (40,000 feet). Subjective turbulence intensity ratings were obtained from air crew members. The air crew often rated given gust accelerations as being more intense during high altitude supersonic flight than during low altitude subsonic flight. The portion of flight distance in turbulence ranged from 6 percent to 8 percent at altitudes between 12.2 kilometers and 16.8 kilometers (40,000 feet and 55,000 feet) to less than 1 percent at altitudes above 18.3 kilometers (60,000 feet). The amount of turbulence varied with season, increasing by a factor of 3 or more from summer to winter. Given values of gust acceleration were less frequent, on the basis of distance traveled, for supersonic flight of the YF-12A airplane at altitudes above 12.2 kilometers (40,000 feet) than for subsonic flight of a jet passenger airplane at altitudes below 12.2 kilometers (40,000 feet). The median thickness of high altitude turbulence patches was less than 400 meters (1300 feet); the median length was less than 16 kilometers (10 miles). The distribution of the patch dimensions tended to be log normal
Is there a patent troll problem in the UK?
This paper reports the findings of an empirical study of patent suits involving non-practicing entities (NPEs) in the U.K. between 2000 and 2010. Overall, we find that NPEs are responsible for 11% of all patent suits filed in the U.K. during this period. Though this is a small percentage by U.S. standards, our study suggests that patent trolling might not be as uniquely American as conventional wisdom suggests. We also find little support for many common explanations for Europe’s relative scarcity of NPE activity. For example, we find that NPEs litigating in the U.K. overwhelmingly assert high-tech patents – even more so, in fact, than their U.S. counterparts – despite higher barriers to software patentability in Europe. Our study does, however, tend to support fee-shifting as a key reason for the U.K.’s immunity to NPEs. We see evidence that the U.K.’s loser-pays legal regime deters NPEs from filing suit, while at the same time encouraging accused infringers to defend claims filed against them. U.K. NPE suits are initiated by potential infringers more often than by NPEs; rarely end in settlement; very rarely end in victory for NPEs; and, thus, result in an attorney’s fee award to the potential infringer more often than a damages award or settlement payment to the patentee. Together, these findings tend to support patent reform bills pending in the U.S. that would implement a fee-shifting regime for patent suits, and may also serve to lessen concerns that Europe’s forthcoming Unified Patent Court will draw NPEs to Europe
Predation by the Nonnative Tokay Gecko, Gekko gecko (Linnaeus 1758), on the native Carolina Wren (Thryothorus ludovicianus) and nonnative Cuban Treefrog (Osteopilus septentrionalis) in Florida, USA
Pandemic: Radiologists’ Ethical and Professional Responsibilities
This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemi
Controlling uranyl oxo group interactions to group 14 elements using polypyrrolic Schiff-base macrocyclic ligands
Heterodinuclear uranyl/group 14 complexes of the aryl- and anthracenyl-linked Schiff-base macrocyclic ligands LMe and LA were synthesised by reaction of UO2(H2L) with M{N(SiMe3)2}2 (M = Ge, Sn, Pb). For complexes of the anthracenyl-linked ligand (LA) the group 14 metal sits out of the N4-donor plane by up to 0.7 Å resulting in relatively short M⋯OUO distances which decrease down the group; however, the solid state structures and IR spectroscopic analyses suggest little interaction occurs between the oxo and group 14 metal. In contrast, the smaller aryl-linked ligand (LMe) enforces greater interaction between the metals; only the PbII complex was cleanly accessible although this complex was relatively unstable in the presence of HN(SiMe3)2 and some organic oxidants. In this case, the equatorial coordination of pyridine-N-oxide causes a 0.08 Å elongation of the endo UO bond and a clear interaction of the uranyl ion with the Pb(II) cation in the second donor compartment
Nonaffine Correlations in Random Elastic Media
Materials characterized by spatially homogeneous elastic moduli undergo
affine distortions when subjected to external stress at their boundaries, i.e.,
their displacements \uv (\xv) from a uniform reference state grow linearly
with position \xv, and their strains are spatially constant. Many materials,
including all macroscopically isotropic amorphous ones, have elastic moduli
that vary randomly with position, and they necessarily undergo nonaffine
distortions in response to external stress. We study general aspects of
nonaffine response and correlation using analytic calculations and numerical
simulations. We define nonaffine displacements \uv' (\xv) as the difference
between \uv (\xv) and affine displacements, and we investigate the
nonaffinity correlation function
and related functions. We introduce four model random systems with random
elastic moduli induced by locally random spring constants, by random
coordination number, by random stress, or by any combination of these. We show
analytically and numerically that scales as A |\xv|^{-(d-2)}
where the amplitude is proportional to the variance of local elastic moduli
regardless of the origin of their randomness. We show that the driving force
for nonaffine displacements is a spatial derivative of the random elastic
constant tensor times the constant affine strain. Random stress by itself does
not drive nonaffine response, though the randomness in elastic moduli it may
generate does. We study models with both short and long-range correlations in
random elastic moduli.Comment: 22 Pages, 18 figures, RevTeX
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Who Needs a Copyright Small Claims Court? Evidence from the U.K.'s IP Enterprise Court
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The Effect of Fee Shifting on Litigation: Evidence from a Court Reform in the UK
We study a U.K. court reform that established a cap on the amount of costs that a successful litigant may recover in a case litigated in the Patents County Court (PCC, now the IP Enterprise Court). We first build a theoretical model showing that the introduction of a costs cap is equivalent to an intermediate cost allocation rule falling between the English and American Rules. Our model suggests that the impact of the introduction of such a fee-shifting rule on the number of claims filed and the settlement rate is ambiguous. It shows, however, that the effect of the costs cap on IP holders' incentives to file a claim is stronger for smaller IP holders. Our empirical analysis of the impact of the costs cap takes advantage of our ability to compare IP litigation in the PCC with IP litigation in the High Court of England and Wales, which was not directly affected by the reform. Contrary to the existing literature, we find that the costs cap increased the number of cases filed by smaller companies and decreased the rate of settlement
Soft lubrication: the elastohydrodynamics of non-conforming and conforming contacts
We study the lubrication of fluid-immersed soft interfaces and show that
elastic deformation couples tangential and normal forces and thus generates
lift. We consider materials that deform easily, due to either geometry (e.g. a
shell) or constitutive properties (e.g. a gel or a rubber), so that the effects
of pressure and temperature on the fluid properties may be neglected. Four
different system geometries are considered: a rigid cylinder moving parallel to
a soft layer coating a rigid substrate; a soft cylinder moving parallel to a
rigid substrate; a cylindrical shell moving parallel to a rigid substrate; and
finally a cylindrical conforming journal bearing coated with a thin soft layer.
In addition, for the particular case of a soft layer coating a rigid substrate
we consider both elastic and poroelastic material responses. For all these
cases we find the same generic behavior: there is an optimal combination of
geometric and material parameters that maximizes the dimensionless normal force
as a function of the softness parameter = hydrodynamic pressure/elastic
stiffness = surface deflection/gap thickness which characterizes the
fluid-induced deformation of the interface. The corresponding cases for a
spherical slider are treated using scaling concepts.Comment: 61 pages, 20 figures, 2 tables, submitted to Physics of Fluid
Uranyl to Uranium(IV) Conversion through Manipulation of Axial and Equatorial Ligands
The controlled manipulation of the axial oxo and equatorial halide ligands in the uranyl dipyrrin complex, UO2Cl(L), allows the uranyl reduction potential to be shifted by 1.53 V into the range accessible to naturally occurring reductants that are present during uranium remediation and storage processes. Abstraction of the equatorial halide ligand to form the uranyl cation causes a 780 mV positive shift in the UV/UIV reduction potential. Borane functionalization of the axial oxo groups causes the spontaneous homolysis of the equatorial U–Cl bond and a further 750 mV shift of this potential. The combined effect of chloride loss and borane coordination to the oxo groups allows reduction of UVI to UIV by H2 or other very mild reductants such as Cp*2Fe. The reduction with H2 is accompanied by a B–C bond cleavage process in the oxo-coordinated borane
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