318 research outputs found
Quantum Separability of the vacuum for Scalar Fields with a Boundary
Using the Green's function approach we investigate separability of the vacuum
state of a massless scalar field with a single Dirichlet boundary. Separability
is demonstrated using the positive partial transpose criterion for effective
two-mode Gaussian states of collective operators. In contrast to the vacuum
energy, entanglement of the vacuum is not modified by the presence of the
boundary.Comment: 4 pages, 1 figure, Revtex, minor corrections. submitted to Phy. Rev.
Quantum mechanics emerges from information theory applied to causal horizons
It is suggested that quantum mechanics is not fundamental but emerges from
classical information theory applied to causal horizons. The path integral
quantization and quantum randomness can be derived by considering information
loss of fields or particles crossing Rindler horizons for accelerating
observers. This implies that information is one of the fundamental roots of all
physical phenomena. The connection between this theory and Verlinde's entropic
gravity theory is also investigated.Comment: REvtex4-1, 6pages, 2 figures, final versio
The characterization and composition of bacterial communities in soils blended with spent foundry sand
The purpose of this research was to characterize the structure and composition of bacterial communities in
sandy loam and silty clay soils amended with 30% spent sand from iron, aluminum, and steel foundries. All spent foundry
sand (SFS) blends were grown with or without perennial ryegrass and samples were collected at 4 weeks and 6 months.
Regions of the 16S rRNA gene were amplified using PCR and subsequently analyzed by DGGE and sequenced for bacterial
identification and phylogenetic classification. Cluster analyses of PCR-DGGE banding patterns revealed that SFS blends
from week 4 and month 6 produced unique clusters, with most ryegrass treatments clustering away from those without
ryegrass. The diversity of the bacterial community revealed that it was generally higher in the SFS blends without ryegrass.
By month 6 in treatments without ryegrass, the diversity in the sandy loam blends was similar to the control, while the
diversity in all silty clay blends was greater than the control. Phylogenetic analysis of bacterial isolates (total of 309) from
the SFS blends showed that they were dominated by Actinobacteria (46%), Proteobacteria (29%), and Bacilli (20%), with
fewer numbers belonging to Bacteroidetes (5%). While the addition of SFS to soil does bring about bacterial community
level changes, these changes are similar to that of blending soil with clean silica sand
Black hole as an Information Eraser
We discuss the identity of black hole entropy and show that the first law of
black hole thermodynamics, in the case of a Schwarzschild black hole, can be
derived from Landauer's principle by assuming that the black hole is one of the
most efficient information erasers in systems of a given temperature. The term
"most efficient" implies that minimal energy is required to erase a given
amount of information. We calculate the discrete mass spectra and the entropy
of a Schwarzschild black hole assuming that the black hole processes
information in unit of bits. The black hole entropy acquires a sub-leading
contribution proportional to the logarithm of its mass-squared in addition to
the usual mass-squared term without an artificial cutoff. We also argue that
the minimum of the black hole mass is .Comment: 12 pages, 4 figures, minor change
Gravity from Quantum Information
It is suggested that the Einstein equation can be derived from Landauer's
principle applied to an information erasing process at a local Rindler horizon
and Jacobson's idea linking the Einstein equation with thermodynamics. When
matter crosses the horizon, the information of the matter disappears and the
horizon entanglement entropy increases to compensate the entropy reduction. The
Einstein equation describes an information-energy relation during this process,
which implies that entropic gravity is related to the quantum entanglement of
the vacuum and has a quantum information theoretic origin.Comment: 7 pages, revtex4-1, 2 figures, recent supporting results adde
Causality Problem in a Holographic Dark Energy Model
In the model of holographic dark energy, there is a notorious problem of
circular reasoning between the introduction of future event horizon and the
accelerating expansion of the universe. We examine the problem after dividing
into two parts, the causality problem of the equation of motion and the
circular logic on the use of the future event horizon. We specify and isolate
the root of the problem from causal equation of motion as a boundary condition,
which can be determined from the initial data of the universe. We show that
there is no violation of causality if it is defined appropriately and the
circular logic problem can be reduced to an initial value problem.Comment: 5 page
Phosphorescent sensor for biological mobile zinc
A new phosphorescent zinc sensor (ZIrF) was constructed, based on an Ir(III) complex bearing two 2-(2,4-difluorophenyl)pyridine (dfppy) cyclometalating ligands and a neutral 1,10-phenanthroline (phen) ligand. A zinc-specific di(2-picolyl)amine (DPA) receptor was introduced at the 4-position of the phen ligand via a methylene linker. The cationic Ir(III) complex exhibited dual phosphorescence bands in CH[subscript 3]CN solutions originating from blue and yellow emission of the dfppy and phen ligands, respectively. Zinc coordination selectively enhanced the latter, affording a phosphorescence ratiometric response. Electrochemical techniques, quantum chemical calculations, and steady-state and femtosecond spectroscopy were employed to establish a photophysical mechanism for this phosphorescence response. The studies revealed that zinc coordination perturbs nonemissive processes of photoinduced electron transfer and intraligand charge-transfer transition occurring between DPA and phen. ZIrF can detect zinc ions in a reversible and selective manner in buffered solution (pH 7.0, 25 mM PIPES) with K[subscript d] = 11 nM and pK[subscript a] = 4.16. Enhanced signal-to-noise ratios were achieved by time-gated acquisition of long-lived phosphorescence signals. The sensor was applied to image biological free zinc ions in live A549 cells by confocal laser scanning microscopy. A fluorescence lifetime imaging microscope detected an increase in photoluminescence lifetime for zinc-treated A549 cells as compared to controls. ZIrF is the first successful phosphorescent sensor that detects zinc ions in biological samples.National Institute of General Medical Sciences (U.S.) (Grant GM065519)Ewha Woman's University (Korea) (RP-Grant 2010
Zero Cosmological Constant and Nonzero Dark Energy from Holographic Principle
It is shown that the first law of thermodynamics and the holographic
principle applied to an arbitrary large cosmic causal horizon naturally demand
the zero cosmological constant and non-zero dynamical dark energy in the form
of the holographic dark energy. Semiclassical analysis shows that the
holographic dark energy has a parameter and an equation of state
comparable to current observational data, if the entropy of the horizon
saturates the Bekenstein-Hawking bound. This result indicates that quantum
field theory should be modified at large scale to explain dark energy. The
relations among dark energy, quantum vacuum energy and entropic gravity are
also discussed.Comment: Revtex 7 pages 2 fig
Drying-mediated patterns in colloid-polymer suspensions
Drying-mediated patterning of colloidal particles is a physical phenomenon that must be understood in inkjet printing technology to obtain crack-free uniform colloidal films. Here we experimentally study the drying-mediated patterns of a model colloid-polymer suspension and specifically observe how the deposit pattern appears after droplet evaporation by varying particle size and polymer concentration. We find that at a high polymer concentration, the ring-like pattern appears in suspensions with large colloids, contrary to suppression of ring formation in suspensions with small colloids thanks to colloidpolymer interactions. We attribute this unexpected reversal behavior to hydrodynamics and size dependence of colloid-polymer interactions. This finding would be very useful in developing control of drying-mediated self-assembly to produce crack-free uniform patterns from colloidal fluids.ope
On the Origin of Entropic Gravity and Inertia
It was recently suggested that quantum field theory is not fundamental but
emerges from the loss of phase space information about matter crossing causal
horizons. Possible connections between this formalism and Verlinde's entropic
gravity and Jacobson's thermodynamic gravity are proposed.
The holographic screen in Verlinde's formalism can be identified as local
Rindler horizons and its entropy as that of the bulk fields beyond the
horizons.
This naturally resolves some issues on entropic gravity.
The quantum fluctuation of the fields is the origin of the thermodynamic
nature of entropic gravity.
It is also suggested that inertia is related to dragging
Rindler horizons.Comment: 9 pages, revtex4-1, 3 figures, accepted for publication in
Foundations of Physic
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