3,138 research outputs found
Les bulles « robustes »:Pourquoi il faut construire des logements en région parisienne
« Bulle » ou « pas bulle » ? La question taraude les observateurs et les acteurs du marchĂ© immobilier français. Nous examinons dans cet article les Ă©lĂ©ments empiriques et thĂ©oriques qui expliquent la hausse des prix rĂ©cente et sa rĂ©sistance aux retournements conjoncturels. En combinant la notion de bulle Ă©conomique, les arguments de lâĂ©conomie spatiale et une analyse dâĂ©conomie politique, nous suggĂ©rons que la valorisation importante de lâimmobilier en France est le rĂ©sultat dâune logique rationnelle et conforte les intĂ©rĂȘts des acteurs locaux. DĂšs lors, la forte valorisation peut ĂȘtre considĂ©rĂ©e comme une « bulle robuste », Ă mĂȘme de rĂ©sister Ă des chocs importants. Cette bulle organise un transfert intergĂ©nĂ©rationnel et peut avoir des effets positifs. Elle peut Ă©galement renforcer la sĂ©grĂ©gation spatiale, alimenter les inĂ©galitĂ©s territoriales et empĂȘcher dâexploiter les Ă©conomies dâagglomĂ©ration possibles. Lâanalyse est dĂ©taillĂ©e sur la rĂ©gion Ile-de-France oĂč ces phĂ©nomĂšnes sont particuliĂšrement marquĂ©s
Electrostatic correlations on the ionic selectivity of cylindrical membrane nanopores
We characterize the role of electrostatic fluctuations on the charge selectivity of cylindrical nanopores confining electrolyte mixtures. To this end, we develop an extended one-loop theory that can account for correlation effects induced by the surface charge, nanoconfinement of the electrolyte, and interfacial polarization charges associated with the low permittivity membrane. We validate the quantitative accuracy of the theory by comparisons with previously obtained Monte-Carlo simulation data from the literature, and scrutinize in detail the underlying forces driving the ionic selectivity of the nanopore. In the biologically relevant case of electrolytes with divalent cations such as CaCl2 in negatively charged nanopores, electrostatic correlations associated with the dense counterion layer in the channel result in an increase of the pore coion density with the surface charge. This peculiarity analogous to the charge inversion phenomenon remains intact for dielectrically inhomogeneous pores, which indicates that the effect should be observable in nanofiltration membranes or DNA-blocked nanopores characterized by a low membrane permittivity. Our results show that a quantitatively accurate consideration of correlation effects is necessary to determine the ionic selectivity of nanopores in the presence of electrolytes with multivalent counterions.Peer reviewe
Chinaâs Weibo: is faster different?
The popularization of microblogging in China represents a new challenge to the stateâs regime of information control. The speed with which information is diffused in the microblogosphere has helped netizens to publicize and express their discontent with the negative consequences of economic growth, income inequalities and official corruption. In some cases, netizen led initiatives have facilitated the mobilization of online public opinion and forced the central government to intervene to redress acts of lower level malfeasance. However, despite the growing corpus of such cases, the government has quickly adapted to the changing internet ecology and is using the same tools to help it maintain control of society by enhancing its claims to legitimacy, circumscribing dissent, identifying malfeasance in its agents and using online public opinion to adapt policy and direct propaganda efforts. This essay reflects on microblogging in the context of the Chinese internet, and argues that successes in breaking scandals and mobilizing opinion against recalcitrant officials should not mask the reality that the government is utilizing the microblogosphere to its own advantage
A new measurement of K+(e4) decay and the s-wave pi-pi-scattering length a00
A sample of 400000 events from the decay K+->pi+pi-e+nu(e)(K(e4)) has been
collected in experiment E865 at the Brookhaven AGS. The analysis of these data
yields new measurements of the K(e4) branching ratio
(4.11+-0.01+-0.11)*10**(-5)), the s-wave pi-pi scattering length
a00=0.228+-0.012+-0.003, and the form factors F, G, and H of the hadronic
current and their dependence on the invariant pi-pi mass
First observation of the decay K+ -> e+ nu mu+ mu-
Experiment 865 at the Brookhaven AGS has observed the decay K^+ -> e^+ nu
mu^+ mu^-. The branching ratio extracted is (1.72 +/- 0.37(stat) +/- 0.17(syst)
+/- 0.19(model)) x 10^{-8} where the third term in the error results from the
use of a model to extrapolate into a kinematic region dominated by background.Comment: 4 pages, 6 figures, Revtex4. Correction to figure and minor text
change
Hydrogen Phases on the Surface of a Strongly Magnetized Neutron Star
The outermost layers of some neutron stars are likely to be dominated by
hydrogen, as a result of fast gravitational settling of heavier elements. These
layers directly mediate thermal radiation from the stars, and determine the
characteristics of X-ray/EUV spectra. For a neutron star with surface
temperature T\lo 10^6 K and magnetic field B\go 10^{12} G, various forms of
hydrogen can be present in the envelope, including atom, poly-molecules, and
condensed metal. We study the physical properties of different hydrogen phases
on the surface of a strongly magnetized neutron star for a wide range of field
strength and surface temperature . Depending on the values of and
, the outer envelope can be either in a nondegenerate gaseous phase or in a
degenerate metallic phase. For T\go 10^5 K and moderately strong magnetic
field, B\lo 10^{13} G, the envelope is nondegenerate and the surface material
gradually transforms into a degenerate Coulomb plasma as density increases. For
higher field strength, G, there exists a first-order phase
transition from the nondegenerate gaseous phase to the condensed metallic
phase. The column density of saturated vapor above the metallic hydrogen
decreases rapidly as the magnetic field increases or/and temperature decreases.
Thus the thermal radiation can directly emerge from the degenerate metallic
hydrogen surface. The characteristics of surface X-ray/EUV emission for
different phases are discussed. A separate study concerning the possibility of
magnetic field induced nuclear fusion of hydrogen on the neutron star surface
is also presented.Comment: TeX, 35 pages including 6 postscript figures. To be published in Ap
Integrated Vegetation Management (IVM) for INDOT Roadsides
With over 90,000 miles of road in Indiana, it is important that adjoining vegetation be maintained for safety concerns, road structure maintenance and aesthetics. Mowing is currently the main form of vegetation management on INDOT (Indiana Department of Transportation) roadside. Ever-increasing fuel costs and the high labor demand associated with mowing leads to millions of dollars spent on in-house and contract mowing cycles each year. Drastic cost reductions can be achieved by reducing mowing cycles through the incorporation of other management tools including herbicide and native plantings. This study provides data on six herbicide tank mixtures (Milestone/Escort; Milestone/Escort/Plateau; Perspective; Perspective/Plateau; Viewpoint/Streamline; and 2,4-D/Escort/Plateau) and two mowing cycles (one-cycle and two-cycle) at six sites across the state. All herbicide treatments decreased broadleaf cover better than mowing treatments. Herbicide treatments containing Plateau, a plant growth regulator that retards cool-season grass growth, had the shortest grass height. Herbicide mixtures without Plateau were still shorter than mowing plots due to the seedhead suppression qualities found in the selective broadleaf herbicides. A cost savings of over 40% is achieved with one application of herbicide in lieu of one cycle of mowing. Further cost savings can be achieved through the planting of native vegetation, which was the focus of the second portion of this project. Four native seed mixes (western wheat, short grass, tall grass and short grass with forbs) were analyzed for use on right-of-ways. Successful native plantings have reduced maintenance costs for many DOTs across the country by eliminating mowing and herbicide needs. Drought and persistent weeds at study sites resulted in a sparse covering of native species during the year after planting. This is not uncommon for native roadside planting studies since many native grass species require two to three growing seasons to establish
An Improved upper limit on the decay K^+ -> pi^+ mu^+ e^-
Based on results of a search for the lepton-family-number-violating decay
with data collected by experiment E865 at the
Alternating Gradient Synchrotron of Brookhaven National Laboratory, we place an
upper limit on the branching ratio at (90% C.L.).
Combining the results with earlier E865 data and those of a previous
experiment, E777, an upper limit on the branching ratio of (90% C.L.) is obtained.Comment: v2: 13 pages, submitted to the Phys. Rev. D v3: 13 pages, resubmitted
to Phys. Rev. D (corrections include: a more detailed overview of the
combined analysis of the available experimntal data
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