74,506 research outputs found
Composite passive damping struts for large precision structures
In the field of viscoelastic dampers, a new strut design comprises a viscoelastic material sandwiched between multiple layers, some of which layers bear and dampen load force. In one embodiment, the layers are composite plies of opposing orientation. In another embodiment, the strut utilizes a viscoelastic layer sandwiched between V-shaped composite plies. In a third embodiment, a viscoelastic layer is sandwiched between sine-shaped plies. Strut strength is equal to or greater than conventional aluminum struts due to the unique high interlaminar shear ply design
Dynamos in Stellar Convection Zones: of Wreaths and Cycles
We live near a magnetic star whose cycles of activity are driven by dynamo
action beneath the surface. In the solar convection zone, rotation couples with
plasma motions to build highly organized magnetic fields that erupt at the
surface and undergo relatively regular cycles of polarity reversal. Despite our
proximity to the Sun, the nature of its dynamo remains elusive, but
observations of other solar-type stars show that surface magnetism is a nearly
ubiquitous feature. In recent time, numerical simulations of convection and
dynamo action have taken tremendous strides forward. Global-scale organization
and cyclic magnetism are being achieved by several groups in distinctly
different solar and stellar simulations. Here I will talk about advances on the
numerical front including wreath-building dynamos which may occupy stellar
convection zones. I will discuss the interplay between the new simulations,
various classes of mean-field models, and current and upcoming solar and
stellar observations.Comment: 10 pages, 5 figures, a4 format; proceedings for SOHO 24/GONG 2010
conference: "A new era of seismology of the Sun and solar-like stars,"
Aix-en-Provence, France, June 27-July 4, 2010 (JPCS
The Microbiota and Health Promoting Characteristics of the Fermented Beverage Kefir
peer-reviewedKefir is a complex fermented dairy product created through the symbiotic fermentation of milk by lactic acid bacteria and yeasts contained within an exopolysaccharide and protein complex called a kefir grain. As with other fermented dairy products, kefir has been associated with a range of health benefits such as cholesterol metabolism and angiotensin-converting enzyme (ACE) inhibition, antimicrobial activity, tumor suppression, increased speed of wound healing, and modulation of the immune system including the alleviation of allergy and asthma. These reports have led to increased interest in kefir as a focus of research and as a potential probiotic-containing product. Here, we review those studies with a particular emphasis on the microbial composition and the health benefits of the product, as well as discussing the further development of kefir as an important probiotic product.The authors are funded through the Teagasc Walsh Fellowship Scheme(2014025)and internal Teagasc funding(RMIS6486). BW is supported by the Canada Research Chairs Program and research in the Cotter laboratory is funded by SFI through the PI award “Obesibiotics”(11/PI/1137)and in the form of a center grant (APC Microbiome Institute Grant Number SFI/12/RC/2273)
Uncovering the Hidden Conflicts in Securities Class Action Litigation: Lessons from the State Street Case
Courts, Congress, and commentators have long worried that stockholder plaintiffs in securities and M&A litigation and their counsel may pursue suits that benefit themselves rather than absent stockholders or the corporations in which they invest. Following congressional reforms that encouraged the appointment of institutional stockholders as lead plaintiffs in securities actions, significant academic commentary has focused on the problem of “pay to play”—the possibility that class action law firms encourage litigation by making donations to politicians with influence over institutional stockholders, particularly public sector pension funds.
A recent federal securities class action in the District of Massachusetts, however, suggests that the networks of influence between class plaintiffs and their counsel are much more complex and difficult to detect. After appointing a special master to look into fee issues, the court discovered that a large class action firm had paid over $4 million in “bare referral” fees to an attorney who did little work on the case but had recommended the larger firm to a public sector pension fund “after considerable favors, political activity, money spent and time dedicated in Arkansas.”
This is only one of the less-visible ways that class counsel may route benefits to class plaintiffs. Current class action processes do not routinely identify these potential conflicts of interest. Instead, they tend to surface when nonlitigants bring them to public attention.
Because neither the lead plaintiff nor the defendants have a strong incentive to voluntarily address these conflicts, we propose revisions to the class certification process that would require class plaintiffs to disclose more information regarding their relationships with class counsel. We also propose that courts routinely appoint special masters or class guardians as part of the settlement approval process to ensure that class plaintiffs’ statements are subject to discovery and adversarial review
Constraint-consistent Runge-Kutta methods for one-dimensional incompressible multiphase flow
New time integration methods are proposed for simulating incompressible
multiphase flow in pipelines described by the one-dimensional two-fluid model.
The methodology is based on 'half-explicit' Runge-Kutta methods, being explicit
for the mass and momentum equations and implicit for the volume constraint.
These half-explicit methods are constraint-consistent, i.e., they satisfy the
hidden constraints of the two-fluid model, namely the volumetric flow
(incompressibility) constraint and the Poisson equation for the pressure. A
novel analysis shows that these hidden constraints are present in the
continuous, semi-discrete, and fully discrete equations.
Next to constraint-consistency, the new methods are conservative: the
original mass and momentum equations are solved, and the proper shock
conditions are satisfied; efficient: the implicit constraint is rewritten into
a pressure Poisson equation, and the time step for the explicit part is
restricted by a CFL condition based on the convective wave speeds; and
accurate: achieving high order temporal accuracy for all solution components
(masses, velocities, and pressure). High-order accuracy is obtained by
constructing a new third order Runge-Kutta method that satisfies the additional
order conditions arising from the presence of the constraint in combination
with time-dependent boundary conditions.
Two test cases (Kelvin-Helmholtz instabilities in a pipeline and liquid
sloshing in a cylindrical tank) show that for time-independent boundary
conditions the half-explicit formulation with a classic fourth-order
Runge-Kutta method accurately integrates the two-fluid model equations in time
while preserving all constraints. A third test case (ramp-up of gas production
in a multiphase pipeline) shows that our new third order method is preferred
for cases featuring time-dependent boundary conditions
Doubly-Fluctuating BPS Solutions in Six Dimensions
We analyze the BPS solutions of minimal supergravity coupled to an
anti-self-dual tensor multiplet in six dimensions and find solutions that
fluctuate non-trivially as a function of two variables. We consider families of
solutions coming from KKM monopoles fibered over Gibbons-Hawking metrics or,
equivalently, non-trivial T^2 fibrations over an R3 base. We find smooth
microstate geometries that depend upon many functions of one variable, but each
such function depends upon a different direction inside the T^2 so that the
complete solution depends non-trivially upon the whole T^2 . We comment on the
implications of our results for the construction of a general superstratum.Comment: 24 page
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