2,321 research outputs found
Quantum carpet interferometry for trapped atomic Bose-Einstein condensates
We propose an ``interferometric'' scheme for Bose-Einstein condensates using
near-field diffraction. The scheme is based on the phenomenon of intermode
traces or quantum carpets; we show how it may be used in the detection of weak
forces.Comment: 4 figures. Submitted to Phys. Rev.
Local probing of the field emission stability of vertically aligned multiwalled carbon nanotubes
Metallic cantilever in high vacuum atomic force microscope has been used as
anode for field emission experiments from densely packed vertically aligned
multi-walled carbon nanotubes. The high spatial resolution provided by the
scanning probe technique allowed precise setting of the tip-sample distance in
the submicron region. The dimension of the probe (curvature radius below 50nm)
allowed to measure current contribution from sample areas smaller than 1um^2.
The study of long-term stability evidenced that on these small areas the field
emission current remains stable (within 10% fluctuations) several hours (at
least up to 72 hours) at current intensities between 10-5A and 10-8A.
Improvement of the current stability has been observed after performing
long-time Joule heating conditioning to completely remove possible adsorbates
on the nanotubes.Comment: 15 pages, 7 figure
Extended nonlocal chiral-quark model for the heavy-light quark systems
In this talk, we report the recent progress on constructing a
phenomenological effective model for the heavy-light quark systems, which
consist of (u,d,s,c,b) quarks, i.e. extended nonlocal chiral-quark model
(ExNLChQM). We compute the heavy-meson weak-decay constants to verify the
validity of the model. From the numerical results, it turns out that (f_D, f_B,
f_{D_s}, f_{B_s})=(207.54,208.13,262.56,262.39) MeV. These values are in
relatively good agreement with experimental data and various theoretical
estimations.Comment: 3 pages, 4 figures, Talk given at the 20th International IUPAP
Conference on Few-Body Problems in Physics (FB20), 20~25 August 2012,
Fukuoka, Japa
Effects of green manure crops and mulching technology on reduction in herbicide and fertilizer use during rice cultivation in Korea
Green manure crops are primarily used in environmentally friendly agricultural practices to reduce the application of chemical fertilizer and herbicide. In this study, a two-year field experiment was conducted to evaluate the effects of paper and plastic mulching with hairy vetch alone or in combination with barley on weed control and rice yield. In addition, treatment effects on soil redox potential (Eh) and the concentration of ammonium (NH4+) in rice paddy were investigated. The results showed that plastic film (10 or 20 μm) and paper mulching with hairy vetch alone had no significant effects on weed density and rice yield when compared with conventional practice (herbicide and fertilizer application) during the first year. However, during the second year, plastic film (20 μm) with partial tillage of hairy vetch alone increased rice yield and decreased weed occurence; but barley and hairy vetch mixture showed opposite trends. Plastic film mulching led to a decrease in soil redox potential, mainly due to the decomposition of soil organic matter. In addition, plastic film mulching increased NH4+-N contents in rice paddy soil. These results suggest that the combination of plastic film with hairy vetch and barley mixture can be used in rice fields to reduce the use of chemical fertilizer and herbicide.Keywords: Green manure, hairy vetch, mulching, rice, weed co
Effect of RF power on the structural, optical and gas sensing properties of RF-sputtered Al doped ZnO thin films
The effect of Radio Frequency (RF) power on the properties of magnetron sputtered Al doped ZnO thin films and the related sensor properties are investigated. A series of 2 wt% Al doped ZnO; Zn0.98Al0.02O (AZO) thin films prepd. with magnetron sputtering at different RF powers, are examd. The structural results reveal a good adhesive nature of thin films with quartz substrates as well as increasing thickness of the films with increasing RF power. Besides, the increasing RF power is found to improve the crystallinity and grain growth as confirmed by X-ray diffraction. On the other hand, the optical transmittance is significantly influenced by the RF power, where the transparency values achieved are higher than 82% for all the AZO thin films and the estd. optical band gap energy is found to decrease with RF power due to an increase in the crystallite size as well as the film thickness. In addn., the defect induced luminescence at low temp. (77 K) and room temp. (300 K) was studied through photoluminescence spectroscopy, it is found that the defect d. of electronic states of the Al3+ ion increases with an increase of RF power due to the increase in the thickness of the film and the crystallite size. The gas sensing behavior of AZO films was studied for NO2 at 350 °C. The AZO film shows a good response towards NO2 gas and also a good relationship between the response and the NO2 concn., which is modeled using an empirical formula. The sensing mechanism of NO2 is discussed
Masses of the \eta_c(nS) and \eta_b(nS) mesons
The hyperfine splittings in heavy quarkonia are studied using new
experimental data on the di-electron widths. The smearing of the spin-spin
interaction is taken into account, while the radius of smearing is fixed by the
known and splittings and appears to
be small, fm. Nevertheless, even with such a small radius
an essential suppression of the hyperfine splittings ( is observed
in bottomonium. For the states the values we
predict (in MeV) are 28, 12, 10, 6, 6, and 3, respectively. In single-channel
approximation for the and charmonium states the splittings 16(2) MeV
and 12(4) MeV are obtained.Comment: 13 pages, no figure
Multiscale Discriminant Saliency for Visual Attention
The bottom-up saliency, an early stage of humans' visual attention, can be
considered as a binary classification problem between center and surround
classes. Discriminant power of features for the classification is measured as
mutual information between features and two classes distribution. The estimated
discrepancy of two feature classes very much depends on considered scale
levels; then, multi-scale structure and discriminant power are integrated by
employing discrete wavelet features and Hidden markov tree (HMT). With wavelet
coefficients and Hidden Markov Tree parameters, quad-tree like label structures
are constructed and utilized in maximum a posterior probability (MAP) of hidden
class variables at corresponding dyadic sub-squares. Then, saliency value for
each dyadic square at each scale level is computed with discriminant power
principle and the MAP. Finally, across multiple scales is integrated the final
saliency map by an information maximization rule. Both standard quantitative
tools such as NSS, LCC, AUC and qualitative assessments are used for evaluating
the proposed multiscale discriminant saliency method (MDIS) against the
well-know information-based saliency method AIM on its Bruce Database wity
eye-tracking data. Simulation results are presented and analyzed to verify the
validity of MDIS as well as point out its disadvantages for further research
direction.Comment: 16 pages, ICCSA 2013 - BIOCA sessio
Retrodiction of Generalised Measurement Outcomes
If a generalised measurement is performed on a quantum system and we do not
know the outcome, are we able to retrodict it with a second measurement? We
obtain a necessary and sufficient condition for perfect retrodiction of the
outcome of a known generalised measurement, given the final state, for an
arbitrary initial state. From this, we deduce that, when the input and output
Hilbert spaces have equal (finite) dimension, it is impossible to perfectly
retrodict the outcome of any fine-grained measurement (where each POVM element
corresponds to a single Kraus operator) for all initial states unless the
measurement is unitarily equivalent to a projective measurement. It also
enables us to show that every POVM can be realised in such a way that perfect
outcome retrodiction is possible for an arbitrary initial state when the number
of outcomes does not exceed the output Hilbert space dimension. We then
consider the situation where the initial state is not arbitrary, though it may
be entangled, and describe the conditions under which unambiguous outcome
retrodiction is possible for a fine-grained generalised measurement. We find
that this is possible for some state if the Kraus operators are linearly
independent. This condition is also necessary when the Kraus operators are
non-singular. From this, we deduce that every trace-preserving quantum
operation is associated with a generalised measurement whose outcome is
unambiguously retrodictable for some initial state, and also that a set of
unitary operators can be unambiguously discriminated iff they are linearly
independent. We then examine the issue of unambiguous outcome retrodiction
without entanglement. This has important connections with the theory of locally
linearly dependent and locally linearly independent operators.Comment: To appear in Physical Review
Absence of zero field muon spin relaxation induced by superconductivity in the B phase of UPt
We present muon spin relaxation measurements performed on crystals of the
heavy fermion superconductor UPt. In zero applied field, contrary to a
previous report, we do not observe an increase of the internal magnetic field
in the lower superconducting phase (the B phase). Our result gives an
experimental upper bound of the magnetic field that could be associated with
the superconducting state.Comment: 4 pages, REVTeX 3.0, 2 PostScript figure
Slow fluctuations in enhanced Raman scattering and surface roughness relaxation
We propose an explanation for the recently measured slow fluctuations and
``blinking'' in the surface enhanced Raman scattering (SERS) spectrum of single
molecules adsorbed on a silver colloidal particle. We suggest that these
fluctuations may be related to the dynamic relaxation of the surface roughness
on the nanometer scale and show that there are two classes of roughness with
qualitatively different dynamics. The predictions agree with measurements of
surface roughness relaxation. Using a theoretical model for the kinetics of
surface roughness relaxation in the presence of charges and optical electrical
fields, we predict that the high-frequency electromagnetic field increases both
the effective surface tension and the surface diffusion constant and thus
accelerates the surface smoothing kinetics and time scale of the Raman
fluctuations in manner that is linear with the laser power intensity, while the
addition of salt retards the surface relaxation kinetics and increases the time
scale of the fluctuations. These predictions are in qualitative agreement with
the Raman experiments
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