Nausicaa - Feminine Threat

Classic

Do Birds of a Feather Flock Together? Immigration Flows and Cultural Clustering in Host Countries

This paper presents a simple theoretical framework in which immigrants have a relative incentive to cluster in host countries where cultural characteristics and imperfect information sustain the segmentation of the labor market and a higher wage in foreign communities. The hypothesis is tested on a panel of immigration flows to OECD countries. The pull effect of cultural communities is supported and it is found that the minimum size of a given cultural community is around 5% of the foreign population. It is also found that the pull effect weakens as the community grows as predicted by the theoretical framework.International migrations; relative incomes; cultural clustering

(DH) Noise and Signal scaling factors in Digital Holography in week illumination: relationship with Shot Noise

We have performed off axis heterodyne holography with very weak illumination by recording holograms of the object with and without object illumination in the same acquisition run. We have experimentally studied, how the reconstructed image signal (with illumination) and noise background (without) scale with the holographic acquisition and reconstruction parameters that are the number of frames, and the number of pixels of the reconstruction spatial filter. The first parameter is related to the frequency bandwidth of detection in time, the second one to the bandwidth in space. The signal to background ratio varies roughly like the inverse of the bandwidth in time and space. We have also compared the noise background with the theoretical shot noise background calculated by Monte Carlo simulation. The experimental and Monte Carlo noise background agree very well together

Phase-resolved heterodyne holographic vibrometry with a strobe local oscillator

We report a demonstration of phase-resolved vibrometry, in which out-of-plane sinusoidal motion is assessed by heterodyne holography. In heterodyne holography, the beam in the reference channel is an optical local oscillator (LO). It is frequency-shifted with respect to the illumination beam to enable frequency conversion within the sensor bandwidth. The proposed scheme introduces a strobe LO, where the reference beam is frequency-shifted and modulated in amplitude, to alleviate the issue of phase retrieval. The strobe LO is both tuned around the first optical modulation side band at the vibration frequency, and modulated in amplitude to freeze selected mechanical vibration states sequentially. The phase map of the vibration can then be derived from the demodulation of successive vibration states

Holographic microscopy reconstruction in both object and image half spaces with undistorted 3D grid

We propose an holographic microscopy reconstruction method, which propagates the hologram, in the object half space, in the vicinity of the object. The calibration yields reconstructions with an undistorted reconstruction grid i.e. with orthogonal $x$, $y$ and $z$ axis and constant pixels pitch. The method is validated with an USAF target imaged by a $\times$60 microscope objective, whose holograms are recorded and reconstructed for different USAF locations along the longitudinal axis: -75 to +75 $\mu$m. Since the reconstruction numerical phase mask, the reference phase curvature and MO form an afocal device, the reconstruction can be interpreted as occurring equivalently in the object or in image half space

High numerical aperture holographic microscopy reconstruction with extended z range

An holographic microscopy reconstruction method compatible with high numerical aperture microscope objective (MO) up to NA=1.4 is proposed. After off axis and reference field curvature corrections, and after selection of the +1 grating order holographic image, a phase mask that transforms the optical elements of the holographic setup into an afocal device is applied in the camera plane. The reconstruction is then made by the angular spectrum method. The field is first propagated in the image half space from the camera to the afocal image of the MO optimal plane (plane for which MO has been designed) by using a quadratic kernel. The field is then propagated from the MO optimal plane to the object with the exact kernel. Calibration of the reconstruction is made by imaging a calibrated object like an USAF resolution target for different positions along $z$. Once the calibration is done, the reconstruction can be made with an object located in any plane $z$. The reconstruction method has been validated experimentally with an USAF target imaged with a NA=1.4 microscope objective. Near-optimal resolution is obtained over an extended range ($\pm 50~\mu$m) of $z$ locations

Two-step distortion-free reconstruction scheme for holographic microscopy

We propose a three-dimensional holographic reconstruction procedure applicable with no a priori knowledge about the recording conditions enabling distortion-free three-dimensional object reconstruction

Why do low- and high-skill workers migrate?: flow evidence from France

With a focus on the role of cultural clustering and income distribution, this paper investigates whether standard determinants influence international migration of workers to France with the same intensity across different skill levels and with or without free mobility. We find that low-skill migrants respond to most push and pull migration factors. High-skill migrants however respond only to financial incentives and cultural clustering does not matter. Migration policy is effective at controlling flows of low-skill migrants but free mobility has no impact on high-skill flows. Hence, France must rely on growing earnings and skillpremium to attract high-skill workers from high income countries

Some exact results on the matter star-product in the half-string formalism

We show that the D25 sliver wavefunction, just as the D-instanton sliver, factorizes when expressed in terms of half-string coordinates. We also calculate analytically the star-product of two zero-momentum eigenstates of $\hat{x}$ using the vertex in the oscillator basis, thereby showing that the star-product in the matter sector can indeed be seen as multiplication of matrices acting on the space of functionals of half strings. We then use the above results to establish that the matrices $\rho_{1,2}$, conjectured by Rastelli, Sen and Zwiebach to be left and right projectors on the sliver, are indeed so.Comment: 27 pages; footnote adde