5,554 research outputs found
Influencia del estrés térmico en la calidad panadera del trigo: progenies con diferentes niveles de sensibilidad
Picos de altas temperaturas durante el llenado del grano de trigo estĂĄn relacionados con modificaciones de la calidad panadera, especialmente con disminuciones en la fuerza de la masa. Se evaluĂł la influencia del estrĂ©s tĂ©rmico en la calidad de progenies de trigo pan clasificĂĄndolas en grupos segĂșn su sensibilidad.Se analizaron 60 progenies de trigo durante 3 años consecutivos. Se tomaron fechas de siembra, espigazĂłn, cosecha y temperaturas mĂĄximas diarias.Se determinĂł, para cada muestra, la variable estrĂ©s tĂ©rmico total (ETT), definida como la sumatoria de grados de los episodios de estrĂ©s tĂ©rmico (al menos 2 dĂas consecutivos con temperaturas > 30 ÂșC) durante el periodo del llenado efectivo del grano, estableciĂ©ndose 3 niveles: bajo, medio y alto. Se midieron proteĂna en grano (PTG), gluten hĂșmedo (GH) y variables mixogrĂĄficas. Se realizaron anĂĄlisis de la varianza y coeficientes de correlaciĂłn de Pearson. Para niveles de ETT medio y alto disminuyeron PTG, GH y altura mixogrĂĄfica (Amix), mientras que la fuerza de la masa medida en tiempo de desarrollo mixogrĂĄfico (TDmix) disminuyĂł sĂłlo en 62% de las muestras. En este sentido, se identificaron genotipos que poseen tolerancia al estrĂ©s tĂ©rmico y una mayor estabilidad de la masa
Formation of a stable deacagonal quasicrystalline Al-Pd-Mn surface layer
We report the in situ formation of an ordered equilibrium decagonal Al-Pd-Mn
quasicrystal overlayer on the 5-fold symmetric surface of an icosahedral
Al-Pd-Mn monograin. The decagonal structure of the epilayer is evidenced by
x-ray photoelectron diffraction, low-energy electron diffraction and electron
backscatter diffraction. This overlayer is also characterized by a reduced
density of states near the Fermi edge as expected for quasicrystals. This is
the first time that a millimeter-size surface of the stable decagonal Al-Pd-Mn
is obtained, studied and compared to its icosahedral counterpart.Comment: Submitted to Phys. Ref. Lett. (18 July 2001
Noise-specific beats in the higher-level Ramsey curves of a transmon qubit
In the higher levels of superconducting transmon devices, and more generally
charge sensitive devices, measurements made in the presence of
low-frequency time-correlated charge noise and quasiparticle-induced
parity flips can give an underestimation of the total dephasing time. The
charge variations manifest as beating patterns observed in the overlay of
several Ramsey fringe curves, and are reproduced with a phenomenological Ramsey
curve model which accounts for the charge variations. dephasing times
which more accurately represent the total dephasing time are obtained. The
phenomenological model is compared with a Lindblad master equation model. Both
models are found to be in agreement with one another and the experimental data.
Finally, the phenomenological formulation enables a simple method in which the
power spectral density (PSD) for the low-frequency noise can be inferred from
the overlay of several Ramsey curves.Comment: 4 pages and 5 main figures, supplementary information has 2 figure
Quantum fluctuations of polarons on molecules
The dynamic Jahn-Teller splitting of the six equivalent polarons due
to quantum fluctuations is studied in the framework of the Bogoliubov-de Gennes
formalism. The tunneling induced level splittings are determined to be and for and
, respectively, which should give rise to observable effects in
experiments.Comment: REVTEX 3.0, 13 pages, to be published in Phys. Rev.
A CTMC study of collisions between protons and molecular ions
We study numerically collisions between protons and molecular ions at
intermediate impact energies by using the Classical Trajectory Monte Carlo
method (CTMC). Total and differential cross sections are computed. The results
are compared with: a) the standard one electron--two nucleon scattering, and b)
the quantum mechanical treatment of the scattering.Comment: ReVTeX, 5 pages + 5 figs. (EPS) To be published in Physica Script
Minimizing energy below the glass thresholds
Focusing on the optimization version of the random K-satisfiability problem,
the MAX-K-SAT problem, we study the performance of the finite energy version of
the Survey Propagation (SP) algorithm. We show that a simple (linear time)
backtrack decimation strategy is sufficient to reach configurations well below
the lower bound for the dynamic threshold energy and very close to the analytic
prediction for the optimal ground states. A comparative numerical study on one
of the most efficient local search procedures is also given.Comment: 12 pages, submitted to Phys. Rev. E, accepted for publicatio
Autonomous clustering using rough set theory
This paper proposes a clustering technique that minimises the need for subjective
human intervention and is based on elements of rough set theory. The proposed algorithm is
unified in its approach to clustering and makes use of both local and global data properties to
obtain clustering solutions. It handles single-type and mixed attribute data sets with ease and
results from three data sets of single and mixed attribute types are used to illustrate the
technique and establish its efficiency
Mid-infrared plasmons in scaled graphene nanostructures
Plasmonics takes advantage of the collective response of electrons to
electromagnetic waves, enabling dramatic scaling of optical devices beyond the
diffraction limit. Here, we demonstrate the mid-infrared (4 to 15 microns)
plasmons in deeply scaled graphene nanostructures down to 50 nm, more than 100
times smaller than the on-resonance light wavelength in free space. We reveal,
for the first time, the crucial damping channels of graphene plasmons via its
intrinsic optical phonons and scattering from the edges. A plasmon lifetime of
20 femto-seconds and smaller is observed, when damping through the emission of
an optical phonon is allowed. Furthermore, the surface polar phonons in SiO2
substrate underneath the graphene nanostructures lead to a significantly
modified plasmon dispersion and damping, in contrast to a non-polar
diamond-like-carbon (DLC) substrate. Much reduced damping is realized when the
plasmon resonance frequencies are close to the polar phonon frequencies. Our
study paves the way for applications of graphene in plasmonic waveguides,
modulators and detectors in an unprecedentedly broad wavelength range from
sub-terahertz to mid-infrared.Comment: submitte
Opportunistic routing in wireless mesh networks
Opportunistic Routing (OR) has been proposed as a way to increase the performance of wireless networks by exploiting its broadcast nature. In OR, instead of pre-selecting a single specific node to be the next-hop as a forwarder for a packet, multiple nodes can potentially be selected as the next-hop forwarder. Thus the source can use multiple potential paths to deliver the packets to the destination. More specially, when the current node transmits a packet, all the candidates that receive the packet successfully will coordinate with each other to determine which one would actually forward the packet according to some criteria, while the other nodes will simply discard the packet. In this chapter, we survey the state of the art in OR, then focus on the candidates selection algorithms and carry out a comparative performance evaluation of the most relevant proposals appeared in the literature.Peer ReviewedPostprint (authorâs final draft
CP violation from noncommutative geometry
If the geometry of space-time is \nc, i.e. , then \nc \cpviolng effects may be manifest at low energies. For a
\nc scale , \cpviol from \ncg is
comparable to that from the Standard Model (SM) alone: the \nc contributions
to and in the -system, may actually dominate
over the Standard Model contributions. Present data permit \ncg to be the
only source of \cpviol. Furthermore the most recent findings for g-2 of the
muon are consistent with predictions from \ncg. If the geometry of space-time
is \nc, , then \nc \cpviolng
effects may be manifest at low energies. For a \nc scale , \cpviol from \ncg is comparable to that from the
Standard Model (SM) alone: the \nc contributions to and
in the K-system, may actually dominate over the Standard
Model contributions. Present data permit \ncg to be the only source of
\cpviol. Furthermore the most recent findings for g-2 of the muon are
consistent with predictions from \ncg.Comment: fixed notation, corrected some typo
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