9,134 research outputs found
Economic Impacts of Cultural Diversity in the Netherlands: Productivity, Utility, and Sorting
This paper identifies the impact of cultural diversity on local economies, by explaining spatial disparities in wages and housing prices across Dutch cities using unique individual panel data of homeowners during the period 1999 and 2008. We distinguish between the effects of spatial sorting based on individual heterogeneity, interactions-based productivity effects, and consumer amenities while controlling for interactions between the labor and housing market. In line with previous literature, we find a positive effect of cultural diversity on average housing prices. After controlling for spatial sorting, the effect of cultural diversity on housing prices is negative. The negative impact of cultural diversity on local housing markets is likely driven by a causal effect between the presence of immigrants and neighborhood quality that outweighs a positive effect of immigrant-induced diversity in consumption goods. © 2013, Wiley Periodicals, Inc
Optimization of a charge-state analyzer for ECRIS beams
A detailed experimental and simulation study of the extraction of a 24 keV
He-ion beam from an ECR ion source and the subsequent beam transport through an
analyzing magnet is presented. We find that such a slow ion beam is very
sensitive to space-charge forces, but also that the neutralization of the
beam's space charge by secondary electrons is virtually complete for beam
currents up to at least 0.5 mA. The beam emittance directly behind the
extraction system is 65 pi mm mrad and is determined by the fact that the ion
beam is extracted in the strong magnetic fringe field of the ion source. The
relatively large emittance of the beam and its non-paraxiality lead, in
combination with a relatively small magnet gap, to significant beam losses and
a five-fold increase of the effective beam emittance during its transport
through the analyzing magnet. The calculated beam profile and phase-space
distributions in the image plane of the analyzing magnet agree well with
measurements. The kinematic and magnet aberrations have been studied using the
calculated second-order transfer map of the analyzing magnet, with which we can
reproduce the phase-space distributions of the ion beam behind the analyzing
magnet. Using the transfer map and trajectory calculations we have worked out
an aberration compensation scheme based on the addition of compensating
hexapole components to the main dipole field by modifying the shape of the
poles. The simulations predict that by compensating the kinematic and geometric
aberrations in this way and enlarging the pole gap the overall beam transport
efficiency can be increased from 16 to 45%
On the size and shape of excluded volume polymers confined between parallel plates
A number of recent experiments have provided detailed observations of the
configurations of long DNA strands under nano-to-micrometer sized confinement.
We therefore revisit the problem of an excluded volume polymer chain confined
between two parallel plates with varying plate separation. We show that the
non-monotonic behavior of the overall size of the chain as a function of
plate-separation, seen in computer simulations and reproduced by earlier
theories, can already be predicted on the basis of scaling arguments. However,
the behavior of the size in a plane parallel to the plates, a quantity observed
in recent experiments, is predicted to be monotonic, in contrast to the
experimental findings. We analyze this problem in depth with a mean-field
approach that maps the confined polymer onto an anisotropic Gaussian chain,
which allows the size of the polymer to be determined separately in the
confined and unconfined directions. The theory allows the analytical
construction of a smooth cross-over between the small plate-separation de
Gennes regime and the large plate-separation Flory regime. The results show
good agreement with Langevin dynamics simulations, and confirm the scaling
predictions.Comment: 15 pages, 3 figure
Soil moisture control of NO turnover and N<sub>2</sub>O release in nitrogen-saturated subtropical forest soils
Acid forest soils in South China experience a chronically elevated input of atmospheric nitrogen (N), turning them into hot spots for gaseous N emissions. Soil moisture is known to be a major controller for the partitioning of gaseous N loss to nitric (NO) and nitrous oxide (N2O), which may be of particular relevance in the monsoonal climate of South China. To study this partitioning in more detail, we determined gas phase kinetics of NO and N2O release during laboratory dry-out of acidic surface soils from the headwater catchment TieShanPing (TSP), situated close to Chongqing, SW China. Soils were sampled from two hydrologically distinct environments, a well-drained hill slope (HS), and a periodically flooded groundwater discharge zone (GDZ). Production and consumption of NO were studied in an automated flow-through system purged with NO-free or NO-spiked air. Production rates peaked at 21% and 18% water filled pore space (WFPS) in HS and GDZ soils, respectively, suggesting nitrification as the dominant process of NO formation in both landscape units. In HS soils, maximum production and consumption occurred at the same WFPS, whereas GDZ soils displayed maximum NO consumption at higher WFPS than maximum production, suggesting that denitrification is an important NO sink in GDZ soils. Net N2O release was largest at 100% WFPS and declined steadily during drying. Integrated over the entire range of soil moisture, potential NO-N loss outweighed potential N2O-N loss, suggesting that N-saturated, acid forest soil is an important NO source
Simulations of elementary processes in entangle wormlike micelles under tension : a kinetic pathway to Y-junctions and shear induced structures
The merging process of two amphiphilic cylindrical micelles has been simulated using a coarse grained model in which amphiphiles are represented as chains of one head particle and four tail particles. In our set-up with twisted boundary conditions, a ring-shaped worm is effectively entangled with itself. Upon stretching the box, putting the worms under tension, a fusion into an H-like structure is observed, which eventually transforms into an almost tensionless structure with two freely gliding Y-junctions. The tensions on the worms never reach the point where scission becomes an alternative to fusion. We end with a short discussion of the possible implications of these observations
Seasonal adjustment of daily data with CAMPLET
In the last decade large data sets have become available, both in terms of the number of time series and with higher frequencies (weekly, daily and even higher). All series may suffer from seasonality, which hides other important fluctuations. Therefore time series are typically seasonally adjusted. However, standard seasonal adjustment methods cannot handle series with higher than monthly frequencies. Recently, Abeln et al. (2019) presented CAMPLET, a new seasonal adjustment method, which does not produce revisions when new observations become available. The aim of this paper is to show the attractiveness of CAMPLET for seasonal adjustment of daily time series. We apply CAMPLET to daily data on the gas system in the Netherlands
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