2,289 research outputs found
Symmetric Periodic Solutions of the Anisotropic Manev Problem
We consider the Manev Potential in an anisotropic space, i.e., such that the
force acts differently in each direction. Using a generalization of the
Poincare' continuation method we study the existence of periodic solutions
for weak anisotropy. In particular we find that the symmetric periodic orbits
of the Manev system are perturbed to periodic orbits in the anisotropic
problem.Comment: Late
Preliminary study on a novel Optimal Placed Sensors method based on Genetic Algorithm
The safeguarding of the historical and cultural heritage is one of the main research topics that has been addressed in recent years. Particular attention was given to the development of structural health monitoring systems that allowed the real time acquisition of different physical quantities that are stored in a cloud and compared with the health limit values of the structures obtained from numerical analysis previously carried out. One of the major problems highlighted by the use of these systems is related to the position and quantity of smart sensors to be used within the structure to be monitored. To avoid this, in this paper an Optimal Sensors Placement method was applied to a case study located in China. In particular, the positioning of the sensors was identified through an optimization workflow that adopt a Multi Objective Optimization engine called "Octopus"in Grasshopper3D. The identified optimal solutions have made it possible to detect the areas of the structure that will be subject to collapse during a seismic event
Simulation and Fast vulnerability analysis of a Chinese masonry pagoda
As an important historical relic of human being, masonry pagoda is the great significance in the eastern and western architectural cultures. Most of the existing masonry pagodas in China which have been seriously damaged urgently need detailed structural safety assessment, repair and reinforcement. The paper choose a Chinese masonry pagoda as a case, conducted a series simulation analysis with Abauqs. Through numerical simulation, the seismic performance of the pagoda can be evaluated, which can not only predict the hidden danger and weak link in its structure, but also provide useful reference for the reinforcement and repair of the pagoda. It also adopts a very convenient 3D CAD method to quickly assess the seismic vulnerability of existing masonry pagoda according the reference
Gravitational Leakage into Extra Dimensions: Probing Dark Energy Using Local Gravity
The braneworld model of Dvali-Gabadadze-Porrati (DGP) is a theory where
gravity is modified at large distances by the arrested leakage of gravitons off
our four-dimensional universe. Cosmology in this model has been shown to
support both "conventional" and exotic explanations of the dark energy
responsible for today's cosmic acceleration. We present new results for the
gravitational field of a clustered matter source on the background of an
accelerating universe in DGP braneworld gravity, and articulate how these
results differ from those of general relativity. In particular, we show that
orbits nearby a mass source suffer a universal anomalous precession as large as
5 microarcseconds/year, dependent only on the graviton's effective linewidth
and the global geometry of the full, five-dimensional universe. Thus, this
theory offers a local gravity correction sensitive to factors that dictate
cosmological history.Comment: 18 pages, 1 figure, revtex. Reference updated. Footnote change
Carbon-atom wires: 1-D systems with tunable properties
This review provides a discussion of the current state of research on linear carbon structures and related materials based on sp-hybridization of carbon atoms (polyynes and cumulenes). We show that such systems have widely tunable properties and thus represent an intriguing and mostly unexplored field for both fundamental and applied sciences. We discuss the rich interplay between the structural, vibrational, and electronic properties focusing on recent advances and the future perspectives of carbon-atom wires and novel hybrid sp–sp2-carbon architectures
TRAIL, OPG, and TWEAK in kidney disease: biomarkers or therapeutic targets?
Ligands and receptors of the tumor necrosis factor (TNF) superfamily regulate immune responses and homeostatic functions with potential diagnostic and therapeutic implications. Kidney disease represents a global public health problem, whose prevalence is rising worldwide, due to the aging of the population and the increasing prevalence of diabetes, hypertension, obesity, and immune disorders. In addition, chronic kidney disease is an independent risk factor for the development of cardiovascular disease, which further increases kidney-related morbidity and mortality. Recently, it has been shown that some TNF superfamily members are actively implicated in renal pathophysiology. These members include TNF-related apoptosis-inducing ligand (TRAIL), its decoy receptor osteoprotegerin (OPG), and TNF-like weaker inducer of apoptosis (TWEAK). All of them have shown the ability to activate crucial pathways involved in kidney disease development and progression (e.g. canonical and non-canonical pathways of the transcription factor nuclear factor-kappa B), as well as the ability to regulate cell proliferation, differentiation, apoptosis, necrosis, inflammation, angiogenesis, and fibrosis with double-edged effects depending on the type and stage of kidney injury. Here we will review the actions of TRAIL, OPG, and TWEAK on diabetic and non-diabetic kidney disease, in order to provide insights into their full clinical potential as biomarkers and/or therapeutic options against kidney disease
On the Lense-Thirring test with the Mars Global Surveyor in the gravitational field of Mars
I discuss some aspects of the recent test of frame-dragging performed by me
by exploiting the Root-Mean-Square (RMS) orbit overlap differences of the
out-of-plane component N of the orbit of the Mars Global Surveyor (MGS)
spacecraft in the gravitational field of Mars. A linear fit of the full time
series of the entire MGS data (4 February 1999-14 January 2005) yields a
normalized slope 1.03 +/- 0.41 (with 95% confidence bounds). Other linear fits
to different data sets confirm the agreement with general relativity. The huge
systematic effects induced by the mismodeling in the martian gravitational
field claimed by some authors are absent in the MGS out-of-plane record. The
non-gravitational forces affect at the same level of the gravitomagnetic one
the in-plane orbital components of MGS, not the out-of-plane one. Moreover,
they experience high-frequency variations which does not matter in the present
case in which secular effects are relevant.Comment: LaTex2e, 8 pages, no figures, no tables, 17 references. It refers to
K. Krogh, Class. Quantum Grav., 24, 5709-5715, 2007 based on
astro-ph/0701653. Final version to appear in CEJP (Central European Journal
of Physics
- …