294 research outputs found
The Idea of Feudalism, from the Philosophes to Karl Marx
The title of this conference -'Feudalism: a comparative study in social and political structures of pre-industrial societies', emphasises the inter-disciplinary approach of our Association. We wish to break down artificial barriers and constraints put upon us by the very organisation of our universities. There are here historians, political scientists, anthropologists, linguists, literary critics and philosophers
Designing policies in uncertain contexts: Entrepreneurial capacity and the European Emission Trading Scheme
The paper focuses on enterprising agents in policy formulation and design by looking at their capacity of dealing with different levels of uncertainty. In climate policy specifically, different degrees and types of uncertainties pose a challenge to policymakers. Policy entrepreneurs and the combination of their analytical, operational and political competences are a relevant component in reducing ambiguity in policy design and translating broad policy goals to operational programmes and specific policy instruments. Using the case of the European Emission Trading Scheme, we suggest that the success of policy entrepreneurs in catalysing policy change is determined by their capacity to work against multiple kinds of uncertainty. This ‘uncertainty mitigating’ capacity on the part of policy entrepreneurs rests significantly on balancing managerial expertise and political acumen. We conclude that entrepreneurial capacity goes beyond current definitions in the literature, involving the balance among analytical, operational and political competences to navigate a politicized policy context.The politics and administration of institutional chang
Groundwater depletion causing reduction of baseflow triggering Ganges river summer drying
In summer (pre-monsoon) of recent years, low water level among the last few decades, has been observed in several lower Indian reaches of the Ganges (or Ganga) river (with estimated river water level depletion rates at the range of −0.5 to −38.1 cm/year between summers of 1999 and 2013 in the studied reaches). Here, we show this Ganges river depletion is related to groundwater baseflow reduction caused by ongoing observed groundwater storage depletion in the adjoining Gangetic aquifers (Ganges basin, −0.30 ± 0.07 cm/year or −2.39 ± 0.56 km3/year). Our estimates show, 2016-baseflow amount (~1.0 × 106 m3/d) has reduced by ~59%, from the beginning of the irrigation-pumping age of 1970s (2.4 × 106 m3/d) in some of the lower reaches. The net Ganges river water reduction could jeopardize domestic water supply, irrigation water requirements, river transport, ecology etc. of densely populated northern Indian plains. River water reduction has direct impact on food production indicating vulnerability to more than 100 million of the population residing in the region. The results of this study could be used to decipher the groundwater-linked river water depletion as well as the regional water security in other densely populated parts of the globe
Scale free networks from a Hamiltonian dynamics
Contrary to many recent models of growing networks, we present a model with
fixed number of nodes and links, where it is introduced a dynamics favoring the
formation of links between nodes with degree of connectivity as different as
possible. By applying a local rewiring move, the network reaches equilibrium
states assuming broad degree distributions, which have a power law form in an
intermediate range of the parameters used. Interestingly, in the same range we
find non-trivial hierarchical clustering.Comment: 4 pages, revtex4, 5 figures. v2: corrected statements about
equilibriu
Magnetic relaxation phenomena and cluster glass properties of La{0.7-x}Y{x}Ca{0.3}MnO{3} manganites
The dynamic magnetic properties of the distorted perovskite system
La{0.7-x}Y{x}Ca{0.3}MnO{3} (0 <= x <= 0.15) have been investigated by
ac-susceptibility and dc magnetization measurements, with emphasis on
relaxation and aging studies. They evidence for x >= 0.10 the appearance of a
metallic cluster glass phase, that develops just below the ferromagnetic
transition temperature. The clusters grow with decreasing temperature down to a
temperature T(f0) at which they freeze due to severe intercluster frustration.
The formation of these clusters is explained by the presence of yttrium induced
local structural distortions that create localized spin disorder in a magnetic
lattice where double-exchange ferromagnetism is dominant.Comment: Accepted for publication in Phys. Rev.
Heavy--light mesons in a bilocal effective theory
Heavy--light mesons are described in an effective quark theory with a
two--body vector--type interaction. The bilocal interaction is taken to be
instantaneous in the rest frame of the bound state, but formulated covariantly
through the use of a boost vector. The chiral symmetry of the light flavor is
broken spontaneously at mean field level. The framework for our discussion of
bound states is the effective bilocal meson action obtained by bosonization of
the quark theory. Mesons are described by 3--dimensional wave functions
satisfying Salpeter equations, which exhibit both Goldstone solutions in the
chiral limit and heavy--quark symmetry for . We present
numerical solutions for pseudoscalar -- and --mesons. Heavy--light meson
spectra and decay constants are seen to be sensitive to the description of
chiral symmetry breaking (dynamically generated vs.\ constant quark mass).Comment: (34 p., standard LaTeX, 7 PostScript figures appended)
UNITUE-THEP-17/9
Photo-production of Nucleon Resonances and Nucleon Spin Structure Function in the Resonance Region
The photo-production of nucleon resonances is calculated based on a chiral
constituent quark model including both relativistic corrections H{rel} and
two-body exchange currents, and it is shown that these effects play an
important role. We also calculate the first moment of the nucleon spin
structure function g1 (x,Q^2) in the resonance region, and obtain a
sign-changing point around Q^2 ~ 0.27 {GeV}^2 for the proton.Comment: 23 pages, 5 figure
Landau-Zener-Stuckelberg interferometry
A transition between energy levels at an avoided crossing is known as a
Landau-Zener transition. When a two-level system (TLS) is subject to periodic
driving with sufficiently large amplitude, a sequence of transitions occurs.
The phase accumulated between transitions (commonly known as the Stuckelberg
phase) may result in constructive or destructive interference. Accordingly, the
physical observables of the system exhibit periodic dependence on the various
system parameters. This phenomenon is often referred to as
Landau-Zener-Stuckelberg (LZS) interferometry. Phenomena related to LZS
interferometry occur in a variety of physical systems. In particular, recent
experiments on LZS interferometry in superconducting TLSs (qubits) have
demonstrated the potential for using this kind of interferometry as an
effective tool for obtaining the parameters characterizing the TLS as well as
its interaction with the control fields and with the environment. Furthermore,
strong driving could allow for fast and reliable control of the quantum system.
Here we review recent experimental results on LZS interferometry, and we
present related theory.Comment: 34 single-column pages, 11 figure
Relativistic Three-Dimensional Two- and Three-Body Equations on a Null Plane and Applications to Meson and Baryon Regge Trtajectories
We start from a field-theoretical model of zero range approximation to derive
three-dimensional relativistic two- and three-body equations on a null plane.
We generalize those equations to finite range interactions. We propose a
three-body null-plane equation whose form is different from the one presented
earlier in the framework of light-cone dynamics. We discuss the choices of the
kernels in two- and three-body cases and apply our model to the description of
meson and baryon Regge trajectories. Our approach overcomes some theoretical
and phenomenological difficulties met in preceding relativized treatments of
the three-body problem.Comment: 35 pages LaTex, 6 figs (available from [email protected]
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