4,390 research outputs found
Hybridization between wild and cultivated potato species in the Peruvian Andes and biosafety implications for deployment of GM potatoes
The nature and extent of past and current hybridization between cultivated potato and wild relatives in nature is of interest to crop evolutionists, taxonomists, breeders and recently to molecular biologists because of the possibilities of inverse gene flow in the deployment of genetically-modified (GM) crops. This research proves that natural hybridization occurs in areas of potato diversity in the Andes, the possibilities for survival of these new hybrids, and shows a possible way forward in case of GM potatoes should prove advantageous in such areas
Subnanosecond spectral diffusion measurement using photon correlation
Spectral diffusion is a result of random spectral jumps of a narrow line as a
result of a fluctuating environment. It is an important issue in spectroscopy,
because the observed spectral broadening prevents access to the intrinsic line
properties. However, its characteristic parameters provide local information on
the environment of a light emitter embedded in a solid matrix, or moving within
a fluid, leading to numerous applications in physics and biology. We present a
new experimental technique for measuring spectral diffusion based on photon
correlations within a spectral line. Autocorrelation on half of the line and
cross-correlation between the two halves give a quantitative value of the
spectral diffusion time, with a resolution only limited by the correlation
set-up. We have measured spectral diffusion of the photoluminescence of a
single light emitter with a time resolution of 90 ps, exceeding by four orders
of magnitude the best resolution reported to date
Bosonic excitations of the AdS4 Reissner-Nordstrom black hole
We study the long-lived modes of the charge density and energy density
correlators in the strongly-coupled, finite density field theory dual to the
AdS4 Reissner-Nordstrom black hole. For small momenta q<<\mu, these correlators
contain a pole due to sound propagation, as well as a pole due to a long-lived,
purely imaginary mode analogous to the \mu=0 hydrodynamic charge diffusion
mode. As the temperature is raised in the range T\lesssim\mu, the sound
attenuation shows no significant temperature dependence. When T\gtrsim\mu, it
quickly approaches the \mu=0 hydrodynamic result where it decreases like 1/T.
It does not share any of the temperature-dependent properties of the 'zero
sound' of Landau Fermi liquids observed in the strongly-coupled D3/D7 field
theory. For such small momenta, the energy density spectral function is
dominated by the sound mode at all temperatures, whereas the charge density
spectral function undergoes a crossover from being dominated by the sound mode
at low temperatures to being dominated by the diffusion mode when T \mu^2/q.
This crossover occurs due to the changing residue at each pole. We also compute
the momentum dependence of these spectral functions and their corresponding
long-lived poles at fixed, low temperatures T<<\mu.Comment: 33 pages, 21 figures, 6 animation
PET probe-guided surgery: applications and clinical protocol
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
On the AC spectrum of one-dimensional random Schroedinger operators with matrix-valued potentials
We consider discrete one-dimensional random Schroedinger operators with
decaying matrix-valued, independent potentials. We show that if the l^2-norm of
this potential has finite expectation value with respect to the product measure
then almost surely the Schroedinger operator has an interval of purely
absolutely continuous (ac) spectrum. We apply this result to Schroedinger
operators on a strip. This work provides a new proof and generalizes a result
obtained by Delyon, Simon, and Souillard.Comment: (1 figure
Service evaluation of weight outcomes as a function of initial BMI in 34,271 adults referred to a primary care/commercial weight management partnership scheme
Peer reviewedPublisher PD
THE ANTIOXIDANT AND ANTIMICROBIAL ACTIVITY OF THE LEAVES EXTRACT OF CLERODENDRUM COLEBROOKIANUM WALP, (FAM: VERBENACEAE)
Objective: To investigate the in-vitro antioxidant and antimicrobial potential of Clerodendrum colebrookianum leaves extract.Methods: The leaves of C. colebrookianum were collected from various parts of Aizawl, Mizoram, India. Subsequently, the leaves were extracted with solvents (chloroform, acetone, ethanol and methanol) in a Soxhlet extraction apparatus for 24hr. Further, the extracts were extensively examined for its in-vitro antioxidant (DPPH) and antimicrobial activities. The preliminary phytochemical screening was carried out using standard protocols.Results: The existence of alkaloids, flavonoids, diterpenes, saponins, glycosides, steroids and terpeinoids were revealed in the phytochemical screening. The aqueous and acetone extract had the highest total phenolic content (2.348 mg/ml), when compared to methanol, ethanol and chloroform extracts, which was 0.549 mg/ml, 0.408 mg/ml and 0.407 mg/ml, respectively. The antioxidant activity was more significant for aqueous extract, when compared to other extracts. The antimicrobial activity was more significant for acetone extract showed significant zone of inhibition of 14±0.3, 13±0.3 and 15±0.2 for E. coli, S. marcescens and S. aureus, respectively.Conclusion: The high level of antioxidant and antimicrobial potential of C. colebrookianum leaf extracts encourage its potential use for biomedical applications
Collective Excitations of Holographic Quantum Liquids in a Magnetic Field
We use holography to study N=4 supersymmetric SU(Nc) Yang-Mills theory in the
large-Nc and large-coupling limits coupled to a number Nf << Nc of
(n+1)-dimensional massless supersymmetric hypermultiplets in the Nc
representation of SU(Nc), with n=2,3. We introduce a temperature T, a baryon
number chemical potential mu, and a baryon number magnetic field B, and work in
a regime with mu >> T,\sqrt{B}. We study the collective excitations of these
holographic quantum liquids by computing the poles in the retarded Green's
function of the baryon number charge density operator and the associated peaks
in the spectral function. We focus on the evolution of the collective
excitations as we increase the frequency relative to T, i.e. the
hydrodynamic/collisionless crossover. We find that for all B, at low
frequencies the tallest peak in the spectral function is associated with
hydrodynamic charge diffusion. At high frequencies the tallest peak is
associated with a sound mode similar to the zero sound mode in the
collisionless regime of a Landau Fermi liquid. The sound mode has a gap
proportional to B, and as a result for intermediate frequencies and for B
sufficiently large compared to T the spectral function is strongly suppressed.
We find that the hydrodynamic/collisionless crossover occurs at a frequency
that is approximately B-independent.Comment: 45 pages, 8 png and 47 pdf images in 22 figure
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