Early life environment and adult enrichment: Effects on fearfulness in laying hens

publishedVersio

High resolution amplitude and phase gratings in atom optics

An atom-field geometry is chosen in which an atomic beam traverses a field interaction zone consisting of three fields, one having frequency $\Omega =c/\lambda$ propagating in the $\hat{z}$ direction and the other two having frequencies $\Omega +\delta_{1}$ and $\Omega +\delta_{2}$ propagating in the -$\hat{z}$ direction. For $n_{1}\delta_{1}+n_{2}\delta_{2}=0$ and $|\delta_{1}| T,|\delta_{2}| T\gg 1$, where $n_{1}$ and $n_{2}$ are positive integers and $T$ is the pulse duration in the atomic rest frame, the atom-field interaction results in the creation of atom amplitude and phase gratings having period $\lambda /[2(n_{1}+n_{2})]$. In this manner, one can use optical fields having wavelength $\lambda$ to produce atom gratings having periodicity much less than $\lambda$.Comment: 11 pages, 14 figure

Universal homodyne tomography with a single local oscillator

We propose a general method for measuring an arbitrary observable of a multimode electromagnetic field using homodyne detection with a single local oscillator. In this method the local oscillator scans over all possible linear combinations of the modes. The case of two modes is analyzed in detail and the feasibility of the measurement is studied on the basis of Monte-Carlo simulations. We also provide an application of this method in tomographic testing of the GHZ state.Comment: 12 pages, 5 figures (8 eps files

Bichromatic atomic lens

We investigate the focusing of three-level atoms with a bichromatic standing wave laser field, using both classical and quantum treatments of the problem. We find that, for the appropriate ratio of detunings to Rabi frequencies, the atoms will experience a periodic potential which is close to harmonic across half an optical wavelength. The field thus becomes equivalent to a periodic array of microlenses, which could be utilized to deposit lines of atoms upon a substrate. We consider and compare two regimes, differentiated by the interaction time of the atoms in the optical field. The first case considered, the Raman-Nath regime, is analogous to the thin lens regime in classical optics. The second case treats the transverse atomic motion within the light field, and investigates the distribution of atoms upon a substrate placed within the field. We investigate the extent to which this case can be modeled classically

Creating a low-dimensional quantum gas using dark states in an inelastic evanescent-wave mirror

We discuss an experimental scheme to create a low-dimensional gas of ultracold atoms, based on inelastic bouncing on an evanescent-wave mirror. Close to the turning point of the mirror, the atoms are transferred into an optical dipole trap. This scheme can compress the phase-space density and can ultimately yield an optically-driven atom laser. An important issue is the suppression of photon scattering due to ``cross-talk'' between the mirror potential and the trapping potential. We propose that for alkali atoms the photon scattering rate can be suppressed by several orders of magnitude if the atoms are decoupled from the evanescent-wave light. We discuss how such dark states can be achieved by making use of circularly-polarized evanescent waves.Comment: 8 pages, 4 figure

Atom focusing by far-detuned and resonant standing wave fields: Thin lens regime

The focusing of atoms interacting with both far-detuned and resonant standing wave fields in the thin lens regime is considered. The thin lens approximation is discussed quantitatively from a quantum perspective. Exact quantum expressions for the Fourier components of the density (that include all spherical aberration) are used to study the focusing numerically. The following lens parameters and density profiles are calculated as functions of the pulsed field area $\theta$: the position of the focal plane, peak atomic density, atomic density pattern at the focus, focal spot size, depth of focus, and background density. The lens parameters are compared to asymptotic, analytical results derived from a scalar diffraction theory for which spherical aberration is small but non-negligible ($\theta \gg 1$). Within the diffraction theory analytical expressions show that the focused atoms in the far detuned case have an approximately constant background density $0.5(1-0.635\theta ^{- 1/2})$ while the peak density behaves as $$, the focal distance or time as $\theta ^{-1}(1+1.27\theta ^{- 1/2})$, the focal spot size as $0.744\theta ^{-3/4}$, and the depth of focus as $1.91\theta ^{- 3/2}$. Focusing by the resonant standing wave field leads to a new effect, a Rabi- like oscillation of the atom density. For the far-detuned lens, chromatic aberration is studied with the exact Fourier results. Similarly, the degradation of the focus that results from angular divergence in beams or thermal velocity distributions in traps is studied quantitatively with the exact Fourier method and understood analytically using the asymptotic results. Overall, we show that strong thin lens focusing is possible with modest laser powers and with currently achievable atomic beam characteristics.Comment: 21 pages, 11 figure

Caspase-2 is upregulated after sciatic nerve transection and its inhibition protects dorsal root ganglion neurons from Apoptosis after serum withdrawal

Sciatic nerve (SN) transection-induced apoptosis of dorsal root ganglion neurons (DRGN) is one factor determining the efficacy of peripheral axonal regeneration and the return of sensation. Here, we tested the hypothesis that caspase-2(CASP2) orchestrates apoptosis of axotomised DRGN both in vivo and in vitro by disrupting the local neurotrophic supply to DRGN. We observed significantly elevated levels of cleaved CASP2 (C-CASP2), compared to cleaved caspase-3 (C-CASP3), within TUNEL+DRGN and DRG glia (satellite and Schwann cells) after SN transection. A serum withdrawal cell culture model, which induced 40% apoptotic death in DRGN and 60% in glia, was used to model DRGN loss after neurotrophic factor withdrawal. Elevated C-CASP2 and TUNEL were observed in both DRGN and DRG glia, with C-CASP2 localisation shifting from the cytosol to the nucleus, a required step for induction of direct CASP2-mediated apoptosis. Furthermore, siRNAmediated downregulation of CASP2 protected 50% of DRGN from apoptosis after serum withdrawal, while downregulation of CASP3 had no effect on DRGN or DRG glia survival. We conclude that CASP2 orchestrates the death of SN-axotomised DRGN directly and also indirectly through loss of DRG glia and their local neurotrophic factor support. Accordingly, inhibiting CASP2 expression is a potential therapy for improving both the SN regeneration response and peripheral sensory recovery

Generic model of an atom laser

We present a generic model of an atom laser by including a pump and loss term in the Gross-Pitaevskii equation. We show that there exists a threshold for the pump above which the mean matter field assumes a non-vanishing value in steady-state. We study the transient regime of this atom laser and find oscillations around the stationary solution even in the presence of a loss term. These oscillations are damped away when we introduce a position dependent loss term. For this case we present a modified Thomas-Fermi solution that takes into account the pump and loss. Our generic model of an atom laser is analogous to the semi-classical theory of the laser.Comment: 15 pages, including 5 figures, submitted to Phys. Rev. A, revised manuscript, file also available at http://www.physik.uni-ulm.de/quan/users/kne

Least-squares inversion for density-matrix reconstruction

We propose a method for reconstruction of the density matrix from measurable time-dependent (probability) distributions of physical quantities. The applicability of the method based on least-squares inversion is - compared with other methods - very universal. It can be used to reconstruct quantum states of various systems, such as harmonic and and anharmonic oscillators including molecular vibrations in vibronic transitions and damped motion. It also enables one to take into account various specific features of experiments, such as limited sets of data and data smearing owing to limited resolution. To illustrate the method, we consider a Morse oscillator and give a comparison with other state-reconstruction methods suggested recently.Comment: 16 pages, REVTeX, 6 PS figures include

The Vlasov limit and its fluctuations for a system of particles which interact by means of a wave field

In two recent publications [Commun. PDE, vol.22, p.307--335 (1997), Commun. Math. Phys., vol.203, p.1--19 (1999)], A. Komech, M. Kunze and H. Spohn studied the joint dynamics of a classical point particle and a wave type generalization of the Newtonian gravity potential, coupled in a regularized way. In the present paper the many-body dynamics of this model is studied. The Vlasov continuum limit is obtained in form equivalent to a weak law of large numbers. We also establish a central limit theorem for the fluctuations around this limit.Comment: 68 pages. Smaller corrections: two inequalities in sections 3 and two inequalities in section 4, and definition of a Banach space in appendix A1. Presentation of LLN and CLT in section 4.3 improved. Notation improve