1,417 research outputs found
Determination of physiological responses on hyacinth (Hyacinthus orientalis) plant exposed to different salt concentrations
Plant growth is restricted by many environmental factors. Soil salinity is considered as an important agricultural problem for dry and semi-dry fields in many regions around the world. It is known that salinity is an important stress factor restricting water and nutrient intake of plants. In this study, the physiological responses of hyacinth (Hyacinthus orientalis) exposed to different salt concentrations (0, 50, 100, 200 and 400 mM) were investigated. The stomata status, osmotic potential, proline content, chlorophyll and caretonoid contents and protein variances were examined in the plants exposed to salt. The physiological responses of the hyacinth varied depending on the salt concentration. Stress was kept under control at concentrations of 50, 100 and 200 mM; however, bulbs were decayed and necrosis was formed on the leaves at concentration of 400 mM. This study on hyacinth will help us to learn about tolerance mechanisms raised by plants with bulb against salt stress. It was seen in this study that the stomata size decreased when the salt concentration was increased and the chlorophyll and caretonoid contents also decreased. A significant decrease was seen in proline content and it increased at 400 mM and some protein bands which existed in control group disappeared in electrophoresis study.Key words: Salt, stress, hyacinth
Inter-valley coherent order and isospin fluctuation mediated superconductivity in rhombohedral trilayer graphene
Superconductivity was recently discovered in rhombohedral trilayer graphene
(RTG) in the absence of a moir\'e potential. Superconductivity is observed
proximate to a metallic state with reduced isospin symmetry, but it remains
unknown whether this is a coincidence or a key ingredient for
superconductivity. Using a Hartree-Fock analysis and constraints from
experiments, we argue that the symmetry breaking is inter-valley coherent (IVC)
in nature. We evaluate IVC fluctuations as a possible pairing glue, and find
that they lead to chiral unconventional superconductivity when the fluctuations
are strong. We further elucidate how the inter-valley Hund's coupling
determines the spin-structure of the IVC ground state and breaks the degeneracy
between spin-singlet and triplet superconductivity. Remarkably, if the normal
state is spin-unpolarized, we find that a ferromagnetic Hund's coupling favors
spin-singlet superconductivity, in agreement with experiments. Instead, if the
normal state is spin-polarized, then IVC fluctuations lead to spin-triplet
pairing.Comment: 8 + 22 pages, 3 + 5 figures; (v2) 8 + 24 pages, 3 + 6 figures,
additional discussion of pairing symmetries; (v3) 9 + 25 pages, 3 + 7
figures, added phase diagram and correlation length estimat
Possible way out of the Hawking paradox: Erasing the information at the horizon
We show that small deviations from spherical symmetry, described by means of
exact solutions to Einstein equations, provide a mechanism to "bleach" the
information about the collapsing body as it falls through the aparent horizon,
thereby resolving the information loss paradox. The resulting picture and its
implication related to the Landauer's principle in the presence of a
gravitational field, is discussed.Comment: 11 pages, Latex. Some comments added to answer to some raised
questions. Typos corected. Final version, to appear in Int. J. Modern. Phys.
Don't Thrash: How to Cache Your Hash on Flash
This paper presents new alternatives to the well-known Bloom filter data
structure. The Bloom filter, a compact data structure supporting set insertion
and membership queries, has found wide application in databases, storage
systems, and networks. Because the Bloom filter performs frequent random reads
and writes, it is used almost exclusively in RAM, limiting the size of the sets
it can represent. This paper first describes the quotient filter, which
supports the basic operations of the Bloom filter, achieving roughly comparable
performance in terms of space and time, but with better data locality.
Operations on the quotient filter require only a small number of contiguous
accesses. The quotient filter has other advantages over the Bloom filter: it
supports deletions, it can be dynamically resized, and two quotient filters can
be efficiently merged. The paper then gives two data structures, the buffered
quotient filter and the cascade filter, which exploit the quotient filter
advantages and thus serve as SSD-optimized alternatives to the Bloom filter.
The cascade filter has better asymptotic I/O performance than the buffered
quotient filter, but the buffered quotient filter outperforms the cascade
filter on small to medium data sets. Both data structures significantly
outperform recently-proposed SSD-optimized Bloom filter variants, such as the
elevator Bloom filter, buffered Bloom filter, and forest-structured Bloom
filter. In experiments, the cascade filter and buffered quotient filter
performed insertions 8.6-11 times faster than the fastest Bloom filter variant
and performed lookups 0.94-2.56 times faster.Comment: VLDB201
The Kibble-Zurek Problem: Universality and the Scaling Limit
Near a critical point, the equilibrium relaxation time of a system diverges
and any change of control/thermodynamic parameters leads to non-equilibrium
behavior. The Kibble-Zurek problem is to determine the dynamical evolution of
the system parametrically close to its critical point when the change is
parametrically slow. The non-equilibrium behavior in this limit is controlled
entirely by the critical point and the details of the trajectory of the system
in parameter space (the protocol) close to the critical point. Together, they
define a universality class consisting of critical exponents-discussed in the
seminal work by Kibble and Zurek-and scaling functions for physical quantities,
which have not been discussed hitherto. In this article, we give an extended
and pedagogical discussion of the universal content in the Kibble-Zurek
problem. We formally define a scaling limit for physical quantities near
classical and quantum transitions for different sets of protocols. We report
computations of a few scaling functions in model Gaussian and large-N problems
and prove their universality with respect to protocol choice. We also introduce
a new protocol in which the critical point is approached asymptotically at late
times with the system marginally out of equilibrium, wherein logarithmic
violations to scaling and anomalous dimensions occur even in the simple
Gaussian problem.Comment: 19 pages,10 figure
Universal dynamical decoherence control of noisy single-and multi-qubit systems
In this article we develop, step by step, the framework for universal
dynamical control of two-level systems (TLS) or qubits experiencing amplitude-
or phase-noise (AN or PN) due to coupling to a thermal bath. A comprehensive
arsenal of modulation schemes is introduced and applied to either AN or PN,
resulting in completely analogous formulae for the decoherence rates, thus
underscoring the unified nature of this universal formalism. We then address
the extension of this formalism to multipartite decoherence control, where
symmetries are exploited to overcome decoherence.Comment: 28 pages, 4 figure
Propuesta Basi a para la Gestion de los Residuos Solidos de la Zona Metropolitana de Co habamba
La zona metropolitana del departamento de Co habamba presenta una serie deproblemas so iales y ambientales a ausa de la mala gestion de los residuos solidos(RS) que se generan en esta region. La mayora de los muni ipios no uenta onun relleno sanitario ade uado y el servi io de re ogida tiene una obertura par ial.Para ontribuir a la solu ion de este problema, se plantea el on epto basi o deun sistema de gestion de RS para toda la zona metropolitana del departamentode Co habamba. Este sistema ontempla la separa ion en el origen de los RS endos fra iones: una fra ion organi a o humeda y el resto de los materiales o fra - ion se a. El sistema de re ogida transportara estos RS separados hasta entrosde transforma ion-re i la je-transferen ia, donde la parte organi a sera pro esadapara transformarla en ompost y la fra ion se a sera sometida a un pro eso dere upera ion manual de materiales. Se re uperara papel, arton, plasti os, vidrioy metales. De esta manera se lograra desviar una fra ion importante de los RSque tienen que ser vertidos en el relleno sanitario y se generara una fuente deingreso para el operador del sistema, situa ion que permitira redu ir los ostosdel servi io a la pobla ion. Los al ulos realizados muestran que se redu ira enun 46 % los requerimientos volumen y de terreno para el relleno sanitario, paraun perodo de a umula ion omprendido entre 2004-2030 (26 a~nos), pasando de14,5 millones de m3, en un es enario sin desvo de RS, a 7,92 millones de m3, sise apli a el sistema propuesto
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