405 research outputs found
Casimir Force on a Micrometer Sphere in a Dip: Proposal of an Experiment
The attractive Casimir force acting on a micrometer-sphere suspended in a
spherical dip, close to the wall, is discussed. This setup is in principle
directly accessible to experiment. The sphere and the substrate are assumed to
be made of the same perfectly conducting material.Comment: 11 pages, 1 figure; to appear in J. Phys. A: Math. Ge
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Word frequency and trends in the development of French vocabulary in lower intermediate students during Year 12 in English schools
Casimir Effect as a Test for Thermal Corrections and Hypothetical Long-Range Interactions
We have performed a precise experimental determination of the Casimir
pressure between two gold-coated parallel plates by means of a micromachined
oscillator. In contrast to all previous experiments on the Casimir effect,
where a small relative error (varying from 1% to 15%) was achieved only at the
shortest separation, our smallest experimental error (%) is achieved
over a wide separation range from 170 nm to 300 nm at 95% confidence. We have
formulated a rigorous metrological procedure for the comparison of experiment
and theory without resorting to the previously used root-mean-square deviation,
which has been criticized in the literature. This enables us to discriminate
among different competing theories of the thermal Casimir force, and to resolve
a thermodynamic puzzle arising from the application of Lifshitz theory to real
metals. Our results lead to a more rigorous approach for obtaining constraints
on hypothetical long-range interactions predicted by extra-dimensional physics
and other extensions of the Standard Model. In particular, the constraints on
non-Newtonian gravity are strengthened by up to a factor of 20 in a wide
interaction range at 95% confidence.Comment: 17 pages, 7 figures, Sixth Alexander Friedmann International Seminar
on Gravitation and Cosmolog
Constraints on Non-Newtonian Gravity from Recent Casimir Force Measurements
Corrections to Newton's gravitational law inspired by extra dimensional
physics and by the exchange of light and massless elementary particles between
the atoms of two macrobodies are considered. These corrections can be described
by the potentials of Yukawa-type and by the power-type potentials with
different powers. The strongest up to date constraints on the corrections to
Newton's gravitational law are reviewed following from the E\"{o}tvos- and
Cavendish-type experiments and from the measurements of the Casimir and van der
Waals force. We show that the recent measurements of the Casimir force gave the
possibility to strengthen the previously known constraints on the constants of
hypothetical interactions up to several thousand times in a wide interaction
range. Further strengthening is expected in near future that makes Casimir
force measurements a prospective test for the predictions of fundamental
physical theories.Comment: 20 pages, crckbked.cls is used, to be published in: Proceedings of
the 18th Course of the School on Cosmology and Gravitation: The Gravitational
Constant. Generalized Gravitational Theories and Experiments (30 April- 10
May 2003, Erice). Ed. by G. T. Gillies, V. N. Melnikov and V. de Sabbata,
20pp. (Kluwer, in print, 2003
Observation of Magnetic Monopoles in Spin Ice
Excitations from a strongly frustrated system, the kagome ice state of the
spin ice Dy2Ti2O7 under magnetic fields along a [111] direction, have been
studied. They are theoretically proposed to be regarded as magnetic monopoles.
Neutron scattering measurements of spin correlations show that close to the
critical point the monopoles are fluctuating between high- and low-density
states, supporting that the magnetic Coulomb force acts between them. Specific
heat measurements show that monopole-pair creation obeys an Arrhenius law,
indicating that the density of monopoles can be controlled by temperature and
magnetic field.Comment: 5 pages, 4 figures; International Conference on Neutron Scattering
2009 (May 7); J. Phys. Soc. Jpn. 78, No.10 (2009) (Received Aug 11, 2009;
accepted Sept 8, 2009; published Oct 13, 2009
Plasmonic nanoparticle monomers and dimers: From nano-antennas to chiral metamaterials
We review the basic physics behind light interaction with plasmonic
nanoparticles. The theoretical foundations of light scattering on one metallic
particle (a plasmonic monomer) and two interacting particles (a plasmonic
dimer) are systematically investigated. Expressions for effective particle
susceptibility (polarizability) are derived, and applications of these results
to plasmonic nanoantennas are outlined. In the long-wavelength limit, the
effective macroscopic parameters of an array of plasmonic dimers are
calculated. These parameters are attributable to an effective medium
corresponding to a dilute arrangement of nanoparticles, i.e., a metamaterial
where plasmonic monomers or dimers have the function of "meta-atoms". It is
shown that planar dimers consisting of rod-like particles generally possess
elliptical dichroism and function as atoms for planar chiral metamaterials. The
fabricational simplicity of the proposed rod-dimer geometry can be used in the
design of more cost-effective chiral metamaterials in the optical domain.Comment: submitted to Appl. Phys.
The structure-function relationship of oncogenic LMTK3
Elucidating signaling driven by lemur tyrosine kinase 3 (LMTK3) could help drug development. Here, we solve the crystal structure of LMTK3 kinase domain to 2.1Ă
resolution, determine its consensus motif and phosphoproteome, unveiling in vitro and in vivo LMTK3 substrates. Via high-throughput homogeneous time-resolved fluorescence screen coupled with biochemical, cellular, and biophysical assays, we identify a potent LMTK3 small-molecule inhibitor (C28). Functional and mechanistic studies reveal LMTK3 is a heat shock protein 90 (HSP90) client protein, requiring HSP90 for folding and stability, while C28 promotes proteasome-mediated degradation of LMTK3. Pharmacologic inhibition of LMTK3 decreases proliferation of cancer cell lines in the NCI-60 panel, with a concomitant increase in apoptosis in breast cancer cells, recapitulating effects of LMTK3 gene silencing. Furthermore, LMTK3 inhibition reduces growth of xenograft and transgenic breast cancer mouse models without displaying systemic toxicity at effective doses. Our data reinforce LMTK3 as a druggable target for cancer therap
Unworking Milton: Steps to a Georgics of the Mind
Traditionally read as a poem about laboring subjects who gain power through abstract and abstracting forms of bodily discipline, John Miltonâs Paradise Lost (1667, 1674) more compellingly foregrounds the erotics of the Garden as a space where humans and nonhumans intra-act materially and sexually. Following Christopher Hill, who long ago pointed to not one but two revolutions in the history of seventeenth-century English radicalismâthe first, âthe one which succeeded[,] . . . the protestant ethicâ; and the second, âthe revolution which never happened,â which sought âcommunal property, a far wider democracy[,] and rejected the protestant ethicââI show how Miltonâs Paradise Lost gives substance to âthe revolution which never happenedâ by imagining a commons, indeed a communism, in which human beings are not at the center of things, but rather constitute one part of the greater ecology of mind within Miltonâs poem. In the space created by this ecological reimagining, plants assume a new agency. I call this reimagining âecology to come.
High temperature asymptotics of thermodynamic functions of electromagnetic field subjected to boundary conditions on a sphere and cylinder
The high temperature asymptotics of thermodynamic functions of
electromagnetic field subjected to boundary conditions with spherical and
cylindrical symmetries are constructed by making use of a general expansion in
terms of heat kernel coefficients and the related determinant. For this, some
new heat kernel coefficients and determinants had to be calculated for the
boundary conditions under consideration. The obtained results reproduce all the
asymptotics derived by other methods in the problems at hand and involve a few
new terms in the high temperature expansions. An obvious merit of this approach
is its universality and applicability to any boundary value problem correctly
formulated.Comment: 27 pages, REVTeX, no figures, no tables, presentations is improved, a
few references are adde
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