13,829 research outputs found
Quantum dynamics of non-relativistic particles and isometric embeddings
It is considered, in the framework of constrained systems, the quantum
dynamics of non-relativistic particles moving on a d-dimensional Riemannian
manifold M isometrically embedded in . This generalizes recent
investigations where M has been assumed to be a hypersurface of . We
show, contrary to recent claims, that constrained systems theory does not
contribute to the elimination of the ambiguities present in the canonical and
path integral formulations of the problem. These discrepancies with recent
works are discussed.Comment: Revtex, 14 page
Dissipation and detection of polaritons in ultrastrong coupling regime
We have investigated theoretically a dissipative polariton system in the
ultrastrong light-matter coupling regime without using the rotating-wave
approximation on system-reservoir coupling. Photons in a cavity and excitations
in matter respectively couple two large ensembles of harmonic oscillators
(photonic and excitonic reservoirs). Inheriting the quantum statistics of
polaritons in the ultrastrong coupling regime, in the ground state of the whole
system, the two reservoirs are not in the vacuum states but they are squeezed
and correlated. We suppose this non-vacuum reservoir state in the master
equation and in the input-output formalism with Langevin equations. Both two
approaches consistently guarantee the decay of polariton system to its ground
state, and no photon detection is also obtained when the polariton system is in
the ground state.Comment: 18 pages, 3 figure
Preparation of macroscopic quantum superposition states of a cavity field via coupling to a superconducting charge qubit
We propose how to generate macroscopic quantum superposition states using a
microwave cavity containing a superconducting charge qubit. Based on the
measurement of charge states, we show that the superpositions of two
macroscopically distinguishable coherent states of a single-mode cavity field
can be generated by a controllable interaction between a cavity field and a
charge qubit. After such superpositions of the cavity field are created, the
interaction can be switched off by the classical magnetic field, and there is
no information transfer between the cavity field and the charge qubit. We also
discuss the generation of the superpositions of two squeezed coherent states.Comment: 6 page
Safety and efficacy of eculizumab in pediatric patients with aHUS, with or without baseline dialysis
Insights into the nature of northwest-to-southeast aligned ionospheric wavefronts from contemporaneous Very Large Array and ionosondes observations
The results of contemporaneous summer nighttime observations of midlatitude
medium scale traveling ionospheric disturbances (MSTIDs) with the Very Large
Array (VLA) in New Mexico and nearby ionosondes in Texas and Colorado are
presented. Using 132, 20-minute observations, several instances of MSTIDs were
detected, all having wavefronts aligned northwest to southeast and mostly
propagating toward the southwest, consistent with previous studies of MSTIDs.
However, some were also found to move toward the northeast. It was found that
both classes of MSTIDs were only found when sporadic-E (Es) layers of moderate
peak density (1.5<foEs<3 MHz) were present. Limited fbEs data from one
ionosonde suggests that there was a significant amount of structure with the Es
layers during observations when foEs>3 MHz that was not present when 1.5<foEs<3
MHz. No MSTIDs were observed either before midnight or when the F-region height
was increasing at a relatively high rate, even when these Es layers were
observed. Combining this result with AE indices which were relatively high at
the time (an average of about 300 nT and maximum of nearly 700 nT), it is
inferred that both the lack of MSTIDs and the increase in F-region height are
due to substorm-induced electric fields. The northeastward-directed MSTIDs were
strongest post-midnight during times when the F-region was observed to be
collapsing relatively quickly. This implies that these two occurrences are
related and likely both caused by rare shifts in F-region neutral wind
direction from southwest to northwest.Comment: Accepted for publication in the Journal of Geophysical Researc
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Keloids and Hypertrophic Scars: Update and Future Directions
Summary: The development of cutaneous pathological scars, namely, hypertrophic scars (HSs) and keloids, involves complex pathways, and the exact mechanisms by which they are initiated, evolved, and regulated remain to be fully elucidated. The generally held concepts that keloids and HSs represent “aberrant wound healing” or that they are “characterized by hyalinized collagen bundles” have done little to promote their accurate clinicopathological classification or to stimulate research into the specific causes of these scars and effective preventative therapies. To overcome this barrier, we review here the most recent findings regarding the pathology and pathogenesis of keloids and HSs. The aberrations of HSs and keloids in terms of the inflammation, proliferation, and remodeling phases of the wound healing process are described. In particular, the significant roles that the extracellular matrix and the epidermal and dermal layers of skin play in scar pathogenesis are examined. Finally, the current hypotheses of pathological scar etiology that should be tested by basic and clinical investigators are detailed. Therapies that have been found to be effective are described, including several that evolved directly from the aforementioned etiology hypotheses. A better understanding of pathological scar etiology and manifestations will improve the clinical and histopathological classification and treatment of these important lesions
Effect Of Surface Charges On The Rates Of Intermolecular Electron-transfer Between De Novo Designed Metalloproteins
A de novo designed coiled-coil metalloprotein was prepared that uses electrostatic interactions to control both its conformational and bimolecular electron-transfer properties. The title protein exists as a coiled-coil heterodimer of the [Ru(trpy)(bpy)-KK(37-mer)] and [Ru(NH3)(5)-EE(37-mer)] polypeptides which is formed by interhelix electrostatic attractions. Circular dichroism studies show that the electrostatic heterodimer has Kd 0.19 +/- 0.03 muM and is 96% helical at high concentrations. Intercomplex electron-transfer reactions were studied that involve the [Ru(NH3)(5)-H21](2+) electron-donor and the [Ru(trpy)(bpy)H21](3+) electron-acceptor belonging to different electrostatic dimers. An important feature of the designed metalloprotein is its two cationic redox centers embedded within protein surfaces having opposite charge. Thus, the Ru-II(NH3)5-H21 site was placed on the surface of one chain of the coiled-coil which was made to be positively charged, and the Ru-III(trpy)(bpy)-H21 site was placed on the surface of the other chain which was negatively charged. The rates of intermolecular electron-transfer increased from (1.9 +/- 0.4) x 10(7) M-1 s(-1) to (3.7 +/- 0.5) x 107 M-1 s(-1) as the ionic strength was increased from 0.01 to 0.20 M. This indicates that the electrostatic repulsion between the ruthenium centers dominates the kinetics of these reactions. However, the presence of the oppositely charged protein surfaces in the coiled-coils creates an electrostatic recognition domain that substantially ameliorates the effects of this repulsion
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