770 research outputs found
Control of the geometric phase and pseudo-spin dynamics on coupled Bose-Einstein condensates
We describe the behavior of two coupled Bose-Einstein condensates in
time-dependent (TD) trap potentials and TD Rabi (or tunneling) frequency, using
the two-mode approach. Starting from Bloch states, we succeed to get analytical
solutions for the TD Schroedinger equation and present a detailed analysis of
the relative and geometric phases acquired by the wave function of the
condensates, as well as their population imbalance. We also establish a
connection between the geometric phases and constants of motion which
characterize the dynamic of the system. Besides analyzing the affects of
temporality on condensates that differs by hyperfine degrees of freedom
(internal Josephson effect), we also do present a brief discussion of a one
specie condensate in a double-well potential
(external Josephson effect).Comment: 1 tex file and 11 figures in pdf forma
Decoherence and thermalization dynamics of a quantum oscillator
We introduce the quantitative measures characterizing the rates of
decoherence and thermalization of quantum systems. We study the time evolution
of these measures in the case of a quantum harmonic oscillator whose relaxation
is described in the framework of the standard master equation, for various
initial states (coherent, `cat', squeezed and number). We establish the
conditions under which the true decoherence measure can be approximated by the
linear entropy . We show that at low temperatures and for
highly excited initial states the decoherence process consists of three
distinct stages with quite different time scales. In particular, the `cat'
states preserve 50% of the initial coherence for a long time interval which
increases logarithmically with increase of the initial energy.Comment: 24 pages, LaTex, 8 ps figures, accepted for publication in J. Opt.
What’s so bad about scientism?
In their attempt to defend philosophy from accusations of uselessness made by prominent scientists, such as Stephen Hawking, some philosophers respond with the charge of ‘scientism.’ This charge makes endorsing a scientistic stance, a mistake by definition. For this reason, it begs the question against these critics of philosophy, or anyone who is inclined to endorse a scientistic stance, and turns the scientism debate into a verbal dispute. In this paper, I propose a different definition of scientism, and thus a new way of looking at the scientism debate. Those philosophers who seek to defend philosophy against accusations of uselessness would do philosophy a much better service, I submit, if they were to engage with the definition of scientism put forth in this paper, rather than simply make it analytic that scientism is a mistake
Microscopic models of quantum jump super-operators
We discuss the quantum jump operation in an open system, and show that jump
super-operators related to a system under measurement can be derived from the
interaction of that system with a quantum measurement apparatus. We give two
examples for the interaction of a monochromatic electromagnetic field in a
cavity (the system) with 2-level atoms and with a harmonic oscillator
(representing two different kinds of detectors). We show that derived quantum
jump super-operators have `nonlinear' form which depends on assumptions made
about the interaction between the system and the detector. A continuous
transition to the standard Srinivas--Davies form of the quantum jump
super-operatoris shown
Nonadiabatic geometric phase induced by a counterpart of the Stark shift
We analyse the geometric phase due to the Stark shift in a system composed of
a bosonic field, driven by time-dependent linear amplification, interacting
dispersively with a two-level (fermionic) system. We show that a geometric
phase factor in the joint state of the system, which depends on the fermionic
state (resulting form the Stark shift), is introduced by the amplification
process. A clear geometrical interpretation of this phenomenon is provided. We
also show how to measure this effect in an interferometric experiment and to
generate geometric "Schrodinger cat"-like states. Finally, considering the
currently available technology, we discuss a feasible scheme to control and
measure such geometric phases in the context of cavity quantum electrodynamics
Colon cancer associated transcript-1 (CCAT1) expression in adenocarcinoma of the stomach
Background: Long non-coding RNAs (lncRNAs) have been shown to have functional roles in cancer biology and are dys-regulated in many tumors. Colon Cancer Associated Transcript -1 (CCAT1) is a lncRNA, previously shown to be significantly up-regulated in colon cancer. The aim of this study is to determine expression levels of CCAT1 in gastric carcinoma (GC). Methods: Tissue samples were obtained from patients undergoing resection for gastric carcinoma (n=19). For each patient, tumor tissue and normal appearing gastric mucosa were taken. Normal gastric tissues obtained from morbidly obese patients, undergoing laparoscopic sleeve gastrectomy served as normal controls (n=19). A human gastric carcinoma cell line (AGS) served as positive control. RNA was extracted from all tissue samples and CCAT1 expression was analyzed using quantitative real time-PCR (qRT-PCR). Results: Low expression of CCAT1 was identified in normal gastric mucosa samples obtained from morbidly obese patients [mean Relative Quantity (RQ) = 1.95±0.4]. AGS human gastric carcinoma cell line showed an elevated level of CCAT1 expression (RQ=8.02). Expression levels of CCAT1 were approximately 10.8 fold higher in GC samples than in samples taken from the negative control group (RQ=21.1±5 vs. RQ=1.95±0.4, respectively, p<0.001). Interestingly, CCAT1 expression was significantly overexpressed in adjacent normal tissues when compared to the negative control group (RQ = 15.25±2 vs. RQ=1.95±0.4, respectively, p<0.001). Tissues obtained from recurrent GC cases showed the highest expression levels (RQ = 88.8±31; p<0.001). Expression levels increased with tumor stage (T4- 36.4±15, T3- 16.1±6, T2- 4.7±1), however this did not reach statistical significance (p=0.2). There was no difference in CCAT1 expression between intestinal and diffuse type GC (RQ=22.4±7 vs. 22.4±16, respectively, p=0.9). Within the normal gastric tissue samples, no significant difference in CCAT1 expression was observed in helicobacter pylori negative and positive patients (RQ= 2.4±0.9 vs. 0.93±0.2, respectively, p=0.13). Conclusion: CCAT1 is up-regulated in gastric cancer, and may serve as a potential bio-marker for early detection and surveillance. © Ivyspring International Publisher
Treatment of ovarian cancer ascites by intra-peritoneal injection of diphtheria toxin A chain-H19 vector: a case report
<p>Abstract</p> <p>Introduction</p> <p>Ovarian cancer ascitic fluid, which contains malignant cells, is usually present in women with an advanced stage disease. There are currently no effective therapies for the treatment of ovarian cancer ascitic fluid. We developed a new therapeutic strategy to target expression of the diphtheria toxin fragment A gene in ovarian tumor cells under the control of H19 regulatory sequences.</p> <p>Case presentation</p> <p>A 64-year-old Caucasian woman was diagnosed with a stage IIIc epithelial ovarian cancer. She suffered from progressive disease, accumulation of malignant ascites that needed to be drained weekly, abdominal pain, vomiting, anorexia and severe weakness. Infusion of the diphtheria toxin A chain-H19 plasmid into the peritoneum of our patient resulted in complete resolution of the ascites with minimum adverse events.</p> <p>Conclusion</p> <p>On the basis of this preliminary experience, we are currently conducting an extensive Phase I study on a larger number of patients in order to assess the safety and preliminary efficacy of this novel patient-oriented treatment approach.</p
A report on the nonlinear squeezed states and their non-classical properties of a generalized isotonic oscillator
We construct nonlinear squeezed states of a generalized isotonic oscillator
potential. We demonstrate the non-existence of dual counterpart of nonlinear
squeezed states in this system. We investigate statistical properties exhibited
by the squeezed states, in particular Mandel's parameter, second-order
correlation function, photon number distributions and parameter in
detail. We also examine the quadrature and amplitude-squared squeezing effects.
Finally, we derive expression for the -parameterized quasi-probability
distribution function of these states. All these information about the system
are new to the literature.Comment: Accepted for publication in J. Phys. A: Math. Theo
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