1,249 research outputs found
IMPACT OF HEALTH INFORMATION ON DEMAND FOR FATS AND OILS IN JAPAN: COINTEGRATION AND A COMPLETE DEMAND SYSTEM APPROACH
This paper deals with the structural change for fats and oils in Japan focusing on the possible influence of health information. The newly developed fat and cholesterol information index appears to reflect the changing health information on fat and cholesterol much better than the ad-hoc cumulative index.Food Consumption/Nutrition/Food Safety,
Label-free optical detection of single enzyme-reactant reactions and associated conformational changes
Monitoring the kinetics and conformational dynamics of single enzymes is
crucial in order to better understand their biological functions as these
motions and structural dynamics are usually unsynchronized among the molecules.
Detecting the enzyme-reactant interactions and associated conformational
changes of the enzyme on a single molecule basis, however, remain as a
challenge with established optical techniques due to the commonly required
labeling of the reactants or the enzyme itself. The labeling process is usually
non-trivial and the labels themselves might skew the physical properties of the
enzyme. Here we demonstrate an optical, label-free method capable of observing
enzymatic interactions and the associated conformational changes on the single
molecule level. We monitor polymerase/DNA interactions via the strong
near-field enhancement provided by plasmonic nanorods resonantly coupled to
whispering gallery modes in microcavities. Specifically, we employ two
different recognition schemes: one in which the kinetics of polymerase/DNA
interactions are probed in the vicinity of DNA-functionalized nanorods, and the
other in which these interactions are probed via the magnitude of
conformational changes in the polymerase molecules immobilized on nanorods. In
both approaches we find that low and high polymerase activities can be clearly
discerned via their characteristic signal amplitude and signal length
distributions. Furthermore, the thermodynamic study of the monitored
interactions suggests the occurrence of DNA polymerization. This work
constitutes a proof-of-concept study of enzymatic activities via plasmonically
enhanced microcavities and establishes an alternative and label-free method
capable of investigating structural changes in single molecules
An Extended Star Formation History for the Galactic Center from Hubble Space Telescope/NICMOS Observations
We present Hubble Space Telescope (HST) Near-Infrared Camera and Multiobject
Spectrometer (NICMOS) observations as evidence that continuous star formation
has created much of the central stellar cusp of the Galaxy. The data are the
deepest ever obtained for a Galactic Center (GC) population, being 50%
complete for \mnk, or initial stellar masses 2 \Msun. We use
Geneva and Padova stellar evolution models to produce synthetic luminosity
functions for burst and continuous star formation scenarios, finding that the
observations are fit best by continuous star formation at a rate that is
consistent with the recent star formation activity that produced the three
massive young clusters in the central 50 \pc. Further, it is not possible to
fit the observations with ancient burst models, such as would be appropriate
for an old population like that in Baade's Window or NGC6528
HST/NICMOS Observations of Massive Stellar Clusters Near the Galactic Center
We report Hubble Space Telescope (HST) Near-infrared Camera and Multi-object
Spectrometer (NICMOS) observations of the Arches and Quintuplet clusters, two
extraordinary young clusters near the Galactic Center. For the first time, we
have identified main sequence stars in the Galactic Center with initial masses
well below 10 Msun. We present the first determination of the initial mass
function (IMF) for any population in the Galactic Center, finding an IMF slope
which is significantly more positive (Gamma approx -0.65) than the average for
young clusters elsewhere in the Galaxy (Gamma approx -1.4). The apparent
turnoffs in the color-magnitude diagrams suggest cluster ages which are
consistent with the ages implied by the mixture of spectral types in the
clusters; we find tau(age) approx 2+/-1 Myr for the Arches cluster, and
tau(age) approx 4+/-1 Myr for the Quintuplet. We estimate total cluster masses
by adding the masses of observed stars down to the 50% completeness limit, and
then extrapolating down to a lower mass cutoff of 1 Msun. Using this method, we
find > 10^4 Msun for the total mass of the Arches cluster. Such a determination
for the Quintuplet cluster is complicated by the double-valued mass-magnitude
relationship for clusters with ages > 3 Myr. We find a lower limit of 6300 Msun
for the total cluster mass, and suggest a best estimate of twice this value
which accounts for the outlying members of the cluster. Both clusters have
masses which place them as the two most massive clusters in the Galaxy.Comment: accepted by ApJ higher resolution versions of figures 1 and 2 can be
found at: ftp://quintup.astro.ucla.edu/nicmos1
Spatial correlations in chaotic nanoscale systems with spin-orbit coupling
We investigate the statistical properties of wave functions in chaotic
nanostructures with spin-orbit coupling (SOC), focussing in particular on
spatial correlations of eigenfunctions. Numerical results from a microscopic
model are compared with results from random matrix theory in the crossover from
the gaussian orthogonal to the gaussian symplectic ensembles (with increasing
SOC); one- and two-point distribution functions were computed to understand the
properties of eigenfunctions in this crossover. It is found that correlations
of wave function amplitudes are suppressed with SOC; nevertheless,
eigenfunction correlations play a more important role in the two-point
distribution function(s), compared to the case with vanishing SOC. Experimental
consequences of our results are discussed.Comment: Submitted to PR
Spin symmetry breaking in bilayer quantum Hall systems
Based on the construction of generalized Halperin wave functions, we predict
the possible existence of a large class of broken spin symmetry states in
bilayer quantum Hall structures, generalizing the recently suggested canted
antiferromgnetic phase to many fractional fillings. We develop the appropriate
Chern-Simons theory, and establish explicitly that the low-lying neutral
excitation is a Goldstone mode and that the charged excitations are bimerons
with continuously tunable (through the canted antiferromagnetic order
parameter) electric charge on the individual merons.Comment: 4 page
Transport and Strong-Correlation Phenomena in Carbon Nanotube Quantum Dots in a Magnetic Field
Transport through carbon nanotube (CNT) quantum dots (QDs) in a magnetic
field is discussed. The evolution of the system from the ultraviolet to the
infrared is analyzed; the strongly correlated (SC) states arising in the
infrared are investigated. Experimental consequences of the physics are
presented -- the SC states arising at various fillings are shown to be
drastically different, with distinct signatures in the conductance and, in
particular, the noise. Besides CNT QDs, our results are also relevant to double
QD systems.Comment: 5 pages, 5 figure
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