66,138 research outputs found
Prolongation Approach to B\"{a}cklund Transformation of Zhiber-Mikhailov-Shabat Equation
The prolongation structure of Zhiber-Mikhailov-Shabat (ZMS) equation is
studied by using Wahlquist-Estabrook's method. The Lax-pair for ZMS equation
and Riccati equations for pseudopotentials are formulated respectively from
linear and nonlinear realizations of the prolongation structure. Based on
nonlinear realization of the prolongation structure, an auto-Bcklund
transformation of ZMS equation is obtained.Comment: Revtex, no figures, to appear in J. Math. Phys. (1996
Fighting against fast speckle decorrelation for light focusing inside live tissue by photon frequency shifting
Light focusing inside live tissue by digital optical phase conjugation (DOPC) has drawn increasing interest due to its potential biomedical applications in optogenetics, microsurgery, phototherapy, and deep-tissue imaging. However, fast physiological motions in a live animal, including blood flow and respiratory motions, produce undesired photon perturbation and thus inevitably deteriorate the performance of light focusing. Here, we develop a photon-frequency-shifting DOPC method to fight against fast physiological motions by switching the states of a guide star at a distinctive frequency. Therefore, the photons tagged by the guide star are well detected at the specific frequency, separating them from the photons perturbed by fast motions. Light focusing was demonstrated in both phantoms in vitro and mice in vivo with substantially improved focusing contrast. This work puts a new perspective on light focusing inside live tissue and promises wide biomedical applications
Ab Initio Approach to the Non-Perturbative Scalar Yukawa Model
We report on the first non-perturbative calculation of the scalar Yukawa
model in the single-nucleon sector up to four-body Fock sector truncation (one
"scalar nucleon" and three "scalar pions"). The light-front Hamiltonian
approach with a systematic non-perturbative renormalization is applied. We
study the -body norms and the electromagnetic form factor. We find that the
one- and two-body contributions dominate up to coupling .
As we approach the coupling , we discover that the
four-body contribution rises rapidly and overtakes the two- and three-body
contributions. By comparing with lower sector truncations, we show that the
form factor converges with respect to the Fock sector expansion.Comment: 8 pages, 12 figures, to be published in Phys. Lett.
Photoacoustic computed tomography guided microrobots for targeted navigation in intestines in vivo
Tremendous progress in synthetic micro/nanomotors has been made for potential biomedical applications. However, existing micro/nanomotor platforms are inefficient for deep tissue imaging and motion control in vivo. Here, we present a photoacoustic computed tomography (PACT) guided investigation of micromotors in intestines in vivo. The micromotors enveloped in microcapsules exhibit efficient propulsion in various biofluids once released. PACT has visualized the migration of micromotor capsules toward the targeted regions in real time in vivo. The integration of the developed microrobotic system and PACT enables deep imaging and precise control of the micromotors in vivo
Free field realization of the current algebra
The current algebra for a {\it generic} positive integer at
general level is investigated. Its free field representation and
corresponding energy-momentum tensor are constructed. The associated screening
currents of the first kind are also presented.Comment: Latex file; 21 pages; V2, typos corrected, the new version appears in
Phys. Rev.
Correlation and entanglement of two-component Bose-Einstein condensates in a double well
We consider a novel system of two-component atomic Bose-Einstein condensate
in a double-well potential. Based on the well-known two-mode approximation, we
demonstrate that there are obvious avoided level-crossings when both
interspecies and intraspecies interactions of two species are increased. The
quantum dynamics of the system exhibits revised oscillating behaviors compared
with a single component condensate. We also examine the entanglement of two
species. Our numerical calculations show the onset of entanglement can be
signed as a violation of Cauchy-Schwarz inequality of second-order cross
correlation function. Consequently, we use Von Neumann entropy to quantity the
degree of entanglement
Why a local moment induces an antiferromagnetic ordering: An RVB picture
Based on a Gutzwiller projected BCS wavefunction, it is shown that a local
S=1/2 moment is present around a vacancy site (zinc impurity) in a form of
staggered magnetic moments, which is a direct consequence of the short-ranged
resonating-valence-bond (RVB) pairing in the spin background.Comment: 4 pages, 3 figure
Label-free high-throughput photoacoustic tomography of suspected circulating melanoma tumor cells in patients in vivo
Significance: Detection and characterization of circulating tumor cells (CTCs), a key determinant of metastasis, are critical for determining risk of disease progression, understanding metastatic pathways, and facilitating early clinical intervention.
Aim: We aim to demonstrate label-free imaging of suspected melanoma CTCs.
Approach: We use a linear-array-based photoacoustic tomography system (LA-PAT) to detect melanoma CTCs, quantify their contrast-to-noise ratios (CNRs), and measure their flow velocities in most of the superficial veins in humans.
Results: With LA-PAT, we successfully imaged suspected melanoma CTCs in patients in vivo, with a CNR >9. CTCs were detected in 3 of 16 patients with stage III or IV melanoma. Among the three CTC-positive patients, two had disease progression; among the 13 CTC-negative patients, 4 showed disease progression.
Conclusions: We suggest that LA-PAT can detect suspected melanoma CTCs in patients in vivo and has potential clinical applications for disease monitoring in melanoma
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