1,696 research outputs found
Drought management: a multi-level governance approach in rural China
Drought has always been a serious problem in many parts of the world, and climate change may further exacerbate this problem. Much literature is available on providing information on drought instruments in rural China covering establishing national drought relief (Zhang et al., 2005) and water scarcity management systems (Qu et al., 2010), promoting water saving and agricultural technology (Huang et al., 2009; Blanke, et al., 2007), analyzing Water Users Association (WUA) (Wang et al., 2010), initiating water pricing measures (Yang et al., 2003; Zhong and Mol, 2010), popularizing agricultural subsidies (Du et al., 2011), and experimenting with policy-oriented microfinance and agricultural insurance (Du, 2003; Zeng and Mu, 2010). But very few has addressed the issues on multi-level governance in this area in general, and in China in particular. This paper focuses on the question: How can an examination of institutional and non-institutional causes of drought and the performance of existing instruments at multiple levels of governance help us to develop more appropriate policy instruments for drought management in China
Magnetic trapping of metastable atomic strontium
We report the magnetic trapping of metastable atomic strontium. Atoms
are cooled in a magneto-optical trap (MOT) operating on the dipole allowed
transition at 461 nm. Decay via
continuously loads a magnetic trap formed by the quadrupole magnetic field of
the MOT. Over atoms at a density of cm and
temperature of 1 mK are trapped. The atom temperature is significantly lower
than what would be expected from the kinetic and potential energy of atoms as
they are transferred from the MOT. This suggests that thermalization and
evaporative cooling are occurring in the magnetic trap.Comment: This paper has been accepted by PR
Lattice Study of Dense Matter with Two Colors and Four Flavors
We present results from a simulation of SU(2) lattice gauge theory with N_f=4
flavors of Wilson fermion and non-zero quark chemical potential mu, using the
same 12^3x24 lattice, bare gauge coupling, and pion mass in cut-off units as a
previous study with N_f=2. The string tension for N_f=4 is found to be
considerably smaller implying smoother gauge field configurations.
Thermodynamic observables and order parameters for superfluidity and color
deconfinement are studied, and comparisons drawn between the two theories.
Results for quark density and pressure as functions of mu are qualitatively
similar for N_f=2 and N_f=4; in both cases there is evidence for a phase in
which baryonic matter is simultaneously degenerate and confined. Results for
the stress-energy tensor, however, suggest that while N_f=2 has a regime where
dilute matter is non-relativistic and weakly-interacting, N_f=4 matter is
relativistic and strongly-interacting for all values of mu above onset.Comment: Horizontal axes of several figures rescaled. Version accepted for
publicatio
Anomalous density of states in a metallic film in proximity with a superconductor
We investigated the local electronic density of states in
superconductor-normal metal (Nb-Au) bilayers using a very low temperature (60
mK) STM. High resolution tunneling spectra measured on the normal metal (Au)
surface show a clear proximity effect with an energy gap of reduced amplitude
compared to the bulk superconductor (Nb) gap. Within this mini-gap, the density
of states does not reach zero and shows clear sub-gap features. We show that
the experimental spectra cannot be described with the well-established Usadel
equations from the quasi-classical theory.Comment: 4 pages, 5 figure
Shear Viscosity to Entropy Density Ratio in Six Derivative Gravity
We calculate shear viscosity to entropy density ratio in presence of four
derivative (with coefficient ) and six derivative (with coefficient
) terms in bulk action. In general, there can be three possible four
derivative terms and ten possible six derivative terms in the Lagrangian. Among
them two four derivative and eight six derivative terms are ambiguous, i.e.,
these terms can be removed from the action by suitable field redefinitions.
Rest are unambiguous. According to the AdS/CFT correspondence all the
unambiguous coefficients (coefficients of unambiguous terms) can be fixed in
terms of field theory parameters. Therefore, any measurable quantities of
boundary theory, for example shear viscosity to entropy density ratio, when
calculated holographically can be expressed in terms of unambiguous
coefficients in the bulk theory (or equivalently in terms of boundary
parameters). We calculate for generic six derivative gravity and find
that apparently it depends on few ambiguous coefficients at order .
We calculate six derivative corrections to central charges and and
express in terms of these central charges and unambiguous coefficients
in the bulk theory.Comment: 29 pages, no figure, V2, results and typos correcte
The compound Poisson limit ruling periodic extreme behaviour of non-uniformly hyperbolic dynamics
We prove that the distributional limit of the normalised number of returns to
small neighbourhoods of periodic points of non-uniformly hyperbolic dynamical
systems is compound Poisson. The returns to small balls around a fixed point in
the phase space correspond to the occurrence of rare events, or exceedances of
high thresholds, so that there is a connection between the laws of Return Times
Statistics and Extreme Value Laws. The fact that the fixed point in the phase
space is a repelling periodic point implies that there is a tendency for the
exceedances to appear in clusters whose average sizes is given by the Extremal
Index, which depends on the expansion of the system at the periodic point.
We recall that for generic points, the exceedances, in the limit, are
singular and occur at Poisson times. However, around periodic points, the
picture is different: the respective point processes of exceedances converge to
a compound Poisson process, so instead of single exceedances, we have entire
clusters of exceedances occurring at Poisson times with a geometric
distribution ruling its multiplicity.
The systems to which our results apply include: general piecewise expanding
maps of the interval (Rychlik maps), maps with indifferent fixed points
(Manneville-Pomeau maps) and Benedicks-Carleson quadratic maps.Comment: To appear in Communications in Mathematical Physic
The dynamics of quark-gluon plasma and AdS/CFT
In these pedagogical lectures, we present the techniques of the AdS/CFT
correspondence which can be applied to the study of real time dynamics of a
strongly coupled plasma system. These methods are based on solving
gravitational Einstein's equations on the string/gravity side of the AdS/CFT
correspondence. We illustrate these techniques with applications to the
boost-invariant expansion of a plasma system. We emphasize the common
underlying AdS/CFT description both in the large proper time regime where
hydrodynamic dynamics dominates, and in the small proper time regime where the
dynamics is far from equilibrium. These AdS/CFT methods provide a fascinating
arena interrelating General Relativity phenomenae with strongly coupled gauge
theory physics.Comment: 35 pages, 3 figures. Lectures at the 5th Aegean summer school, `From
gravity to thermal gauge theories: the AdS/CFT correspondence'. To appear in
the proceedings in `Lecture Notes in Physics
Optimal Allocation of Capacitor Bank in Radial Distribution System using Analytical Approach
In this paper, a novel analytical technique is proposed for optimal allocation of shunt capacitor bank in radial distribution system. An objective function is formulated to determine the optimal size, number and location of capacitor bank for real & reactive power loss reduction, voltage profile enhancement and annual cost saving. A new constant, Power Voltage Sensitivity Constant (PVSC), has been proposed here. The value of PVSC constant decides the candidate bus location and size. The achievability of the proposed method has been demonstrated on IEEE-69 bus and real distribution system of Jamawaramgarh, Jaipur city. The obtained results are compared with latest optimization techniques to show the effectiveness and robustness of the proposed technique
Certain subclasses of multivalent functions defined by new multiplier transformations
In the present paper the new multiplier transformations
\mathrm{{\mathcal{J}% }}_{p}^{\delta }(\lambda ,\mu ,l) (\delta ,l\geq
0,\;\lambda \geq \mu \geq 0;\;p\in \mathrm{% }%\mathbb{N} )} of multivalent
functions is defined. Making use of the operator two new subclasses and \textbf{\ }of multivalent analytic
functions are introduced and investigated in the open unit disk. Some
interesting relations and characteristics such as inclusion relationships,
neighborhoods, partial sums, some applications of fractional calculus and
quasi-convolution properties of functions belonging to each of these subclasses
and
are
investigated. Relevant connections of the definitions and results presented in
this paper with those obtained in several earlier works on the subject are also
pointed out
Critical temperature for the two-dimensional attractive Hubbard Model
The critical temperature for the attractive Hubbard model on a square lattice
is determined from the analysis of two independent quantities, the helicity
modulus, , and the pairing correlation function, . These
quantities have been calculated through Quantum Monte Carlo simulations for
lattices up to , and for several densities, in the
intermediate-coupling regime. Imposing the universal-jump condition for an
accurately calculated , together with thorough finite-size scaling
analyses (in the spirit of the phenomenological renormalization group) of
, suggests that is considerably higher than hitherto assumed.Comment: 5 pages, 6 figures. Accepted for publication in Phys. Rev.
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