234,330 research outputs found
Electromagnetic Force in Dispersive and Transparent Media
A hydrodynamic-type, macroscopic theory was set up recently to simultaneously
account for dissipation and dispersion of electromagnetic field, in
nonstationary condensed systems of nonlinear constitutive relations~\cite{JL}.
Since it was published in the letter format, some algebra and the more subtle
reasonings had to be left out. Two of the missing parts are presented in this
paper: How algebraically the new results reduce to the known old ones; and more
thoughts on the range of validity of the new theory, especially concerning the
treatment of dissipation.Comment: 10 pages, 0 figur
On the Cauchy problem for Gross-Pitaevskii hierarchies
The purpose of this paper is to investigate the Cauchy problem for the
Gross-Pitaevskii infinite linear hierarchy of equations on We prove local existence and uniqueness of solutions in certain
Sobolev type spaces of sequences of marginal
density operators with In particular, we give a clear
discussion of all cases which covers the local well-posedness
problem for Gross-Pitaevskii hierarchy in this situation.Comment: 17 pages. The referee's comments and suggestions have been
incorporated into this version of the pape
Discriminative Cooperative Networks for Detecting Phase Transitions
The classification of states of matter and their corresponding phase
transitions is a special kind of machine-learning task, where physical data
allow for the analysis of new algorithms, which have not been considered in the
general computer-science setting so far. Here we introduce an unsupervised
machine-learning scheme for detecting phase transitions with a pair of
discriminative cooperative networks (DCN). In this scheme, a guesser network
and a learner network cooperate to detect phase transitions from fully
unlabeled data. The new scheme is efficient enough for dealing with phase
diagrams in two-dimensional parameter spaces, where we can utilize an active
contour model -- the snake -- from computer vision to host the two networks.
The snake, with a DCN "brain", moves and learns actively in the parameter
space, and locates phase boundaries automatically
Observations of Feedback from Radio-Quiet Quasars: I. Extents and Morphologies of Ionized Gas Nebulae
Black hole feedback -- the strong interaction between the energy output of
supermassive black holes and their surrounding environments -- is routinely
invoked to explain the absence of overly luminous galaxies, the black hole vs.
bulge correlations and the similarity of black hole accretion and star
formation histories. Yet direct probes of this process in action are scarce and
limited to small samples of active nuclei. We present Gemini IFU observations
of the distribution of ionized gas around luminous, obscured, radio-quiet (RQ)
quasars at z~0.5. We detect extended ionized gas nebulae via [O III]5007
emission in every case, with a mean diameter of 28 kpc. These nebulae are
nearly perfectly round. The regular morphologies of nebulae around RQ quasars
are in striking contrast with lumpy or elongated nebulae seen around radio
galaxies at low and high redshifts. We present the uniformly measured
size-luminosity relationship of [O III] nebulae around Seyfert 2 galaxies and
type 2 quasars spanning 6 orders of magnitude in luminosity and confirm the
flat slope of the correlation (R ~ L^{0.25+/-0.02}). We find a universal
behavior of the [O III]/H-beta ratio in our entire RQ quasar sample: it
persists at a constant value (~10) in the central regions, until reaching a
"break" isophotal radius ranging from 4 to 11 kpc where it starts to decrease.
We propose a model of clumpy nebulae in which clouds that produce line emission
transition from being ionization-bounded at small distances from the quasar to
being matter-bounded in the outer parts of the nebula, which qualitatively
explains the observed line ratio and surface brightness profiles. It is
striking that we see such smooth and round large-scale gas nebulosities in this
sample, which are inconsistent with illuminated merger debris and which we
suggest may be the signature of accretion energy from the nucleus reaching gas
at large scales.Comment: 44 pages, 11 figures, 3 tables. Accepted for publication in MNRA
Observations of Feedback from Radio-Quiet Quasars - II. Kinematics of Ionized Gas Nebulae
The prevalence and energetics of quasar feedback is a major unresolved
problem in galaxy formation theory. In this paper, we present Gemini Integral
Field Unit observations of ionized gas around eleven luminous, obscured,
radio-quiet quasars at z~0.5 out to ~15 kpc from the quasar; specifically, we
measure the kinematics and morphology of [O III]5007 emission. The round
morphologies of the nebulae and the large line-of-sight velocity widths (with
velocities containing 80% of the emission as high as 1000 km/s combined with
relatively small velocity difference across them (from 90 to 520 km/s) point
toward wide-angle quasi-spherical outflows. We use the observed velocity widths
to estimate a median outflow velocity of 760 km/s, similar to or above the
escape velocities from the host galaxies. The line-of-sight velocity dispersion
declines slightly toward outer parts of the nebulae (by 3% per kpc on average).
The majority of nebulae show blueshifted excesses in their line profiles across
most of their extents, signifying gas outflows. For the median outflow
velocity, we find a kinetic energy flow between 4x10^{44} and 3x10^{45} erg/s
and mass outflow rate between 2000 and 20000 Msun/yr. These values are large
enough for the observed quasar winds to have a significant impact on their host
galaxies. The median rate of converting bolometric luminosity to kinetic energy
of ionized gas clouds is ~2%. We report four new candidates for "super-bubbles"
-- outflows that may have broken out of the denser regions of the host galaxy.Comment: 23 pages, 10 figures, 2 tables, accepted for publication in MNRA
Rotating Superconductors and the Frame-independent London Equation
A frame-independent, thermodynamically exact London equation is presented,
which is especially valid for rotating superconductors. A direct result is the
unexpectedly high accuracy () for the usual expression of the
London moment.Comment: 4 pages, 0 figure
Whole-blood sorting, enrichment and in situ immunolabeling of cellular subsets using acoustic microstreaming
Analyzing undiluted whole human blood is a challenge due to its complex composition of hematopoietic cellular populations, nucleic acids, metabolites, and proteins. We present a novel multi-functional microfluidic acoustic streaming platform that enables sorting, enrichment and in situ identification of cellular subsets from whole blood. This single device platform, based on lateral cavity acoustic transducers (LCAT), enables (1) the sorting of undiluted donor whole blood into its cellular subsets (platelets, RBCs, and WBCs), (2) the enrichment and retrieval of breast cancer cells (MCF-7) spiked in donor whole blood at rare cell relevant concentrations (10 mL− 1), and (3) on-chip immunofluorescent labeling for the detection of specific target cellular populations by their known marker expression patterns. Our approach thus demonstrates a compact system that integrates upstream sample processing with downstream separation/enrichment, to carry out multi-parametric cell analysis for blood-based diagnosis and liquid biopsy blood sampling
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