Policies on illegal immigration in a federation

Illegal immigration is a major policy challenge in Europe, in particular in countries on the external border of the EU such as Italy or Spain. However, there are likely to be important effects on the rest of the EU, too, depending on the policies against illegal immigration in border countries. This paper determines optimal enforcement and amnesty policies on illegal immigration in a federation with border and non-border countries. We show that in the Nash equilibrium with positive enforcement spending in both countries, total enforcement spending is too low to maximize joint welfare. In this case, we find that a side payment can be necessary to achieve the cooperative optimum, depending on the relative size of populations in the two countries.illegal immigration, enforcement, amnesty, EU cooperation

Policies on illegal immigration in a federation

Illegal immigration is a major policy challenge in Europe, in particular in countries on the external border of the EU such as Italy or Spain. However, there are likely to be important eects on the rest of the EU, too, depending on the policies against illegal immigration in border countries. This paper determines optimal enforcement and amnesty policies on illegal immigration in a federation with border and non-border countries. We show that in the Nash equilibrium with positive enforcement spending in both countries, total enforcement spending is too low to maximize joint welfare. We nd that in this case a side payment can be necessary to achieve the cooperative optimum, depending on the relative size of populations in the two countries.

Direct frequency-comb-driven Raman transitions in the terahertz range

We demonstrate the use of a femtosecond frequency comb to coherently drive stimulated Raman transitions between terahertz-spaced atomic energy levels. More specifically, we address the $3d~^2D_{3/2}$ and $3d~^2D_{5/2}$ fine structure levels of a single trapped $^{40}$Ca$^+$ ion and spectroscopically resolve the transition frequency to be $\nu_D = 1{,}819{,}599{,}021{,}534 \pm 8$ Hz. The achieved accuracy is nearly a factor of five better than the previous best Raman spectroscopy, and is currently limited by the stability of our atomic clock reference. Furthermore, the population dynamics of frequency-comb-driven Raman transitions can be fully predicted from the spectral properties of the frequency comb, and Rabi oscillations with a contrast of 99.3(6)\% and millisecond coherence time has been achieved. Importantly, the technique can be easily generalized to transitions in the sub-kHz to tens of THz range and should be applicable for driving, e.g., spin-resolved rovibrational transitions in molecules and hyperfine transitions in highly charged ions.Comment: 9 pages, 8 figure

Strukturierte Promotionsprogramme in den Sozialwissenschaften

Die Doktorandenausbildung in den Sozialwissenschaften, bisher noch ein origi­ näres Recht der Universitäten, weist eine Reihe von Defiziten auf, wie hohe Ab­ bruchquoten, lange Promotionsdauer und schwierige Arbeitsmarkteinmündungen zeigen. Gleichzeitig liegen bisher nur wenig gesicherte Erkenntnisse über deren Ur­ sachen und Möglichkeiten der Verbesserung dieser Ausbildungsphase vor. Anglo­ amerikanische Ausbildungsmodelle lassen sich nicht ohne weiteres auf die Ausbil­ dungsorganisation deutscher Universitäten übertragen, so dass die auf europäischer und nationaler Ebene geforderte Reform der Doktorandenausbildung nicht leicht zu bewerkstelligen ist. Der Beitrag diskutiert am Beispiel der Graduate School of Social Sciences (GSSS) an der Universität Bremen, die in den letzten fünf Jahren erfolgreich eine forschungsorientierte international ausgerichtete Doktorandenaus­ bildung aufgebaut  hat,  wesentliche Strukturelemente eines innovativen  Ausbil­ dungs-, Betreuungs- und Organisationskonzeptes. Anschließend werden mit Blick auf den Trend zur Einrichtung weiterer sozialwissenschaftlicher Doktoranden­ programme und Graduate Schools die fachlichen, administrativen und infrastruk­ turellen Voraussetzungen für eine nachhaltige Reform dieser Ausbildungsphase an­ gesprochen. Social Sciences Graduate Education is characterised by deficits such as high attrition rates, long time-to-degree and uncertain career paths. At the same time we know little about reasons and remedies for these problems. Moreover, the well established Anglo-American Graduate School models do not provide ready-made blueprints for German universities. Thus, an encompassing reform of graduate education called for by the EU and national actors alike poses substantial challenges to the German higher education system. Drawing on the experience of five years of successful doctoral education at the Graduate School of Social Scien­ ces (GSSS) at the University of Bremen, the authors examine crucial elements of this novel type of structured research-oriented graduate education. In the light of the recent trend to set up a variety of graduate programs and schools we also address prerequisites – scientific, administrative and financial – for a sustainable reform of Social Sciences doctoral education

Dopamine D3 Receptors Inhibit Hippocampal Gamma Oscillations by Disturbing CA3 Pyramidal Cell Firing Synchrony

Cortical gamma oscillations are associated with cognitive processes and are altered in several neuropsychiatric conditions such as schizophrenia and Alzheimer’s disease. Since dopamine D3 receptors are possible targets in treatment of these conditions, it is of great importance to understand their role in modulation of gamma oscillations. The effect of D3 receptors on gamma oscillations and the underlying cellular mechanisms were investigated by extracellular local field potential and simultaneous intracellular sharp micro-electrode recordings in the CA3 region of the hippocampus in vitro. D3 receptors decreased the power and broadened the bandwidth of gamma oscillations induced by acetylcholine or kainate. Blockade of the D3 receptors resulted in faster synchronization of the oscillations, suggesting that endogenous dopamine in the hippocampus slows down the dynamics of gamma oscillations by activation of D3 receptors. Investigating the underlying cellular mechanisms for these effects showed that D3 receptor activation decreased the rate of action potentials (APs) during gamma oscillations and reduced the precision of the AP phase coupling to the gamma cycle in CA3 pyramidal cells. The results may offer an explanation how selective activation of D3 receptors may impair cognition and how, in converse, D3 antagonists may exert pro-cognitive and antipsychotic effects

Unresolved sideband photon recoil spectroscopy of molecular ions

We reflect on the prospect of exploiting the recoil associated with absorption and emission of photons to perform spectroscopy of a single molecular ion. For this recoil to be detectable, the molecular ion is sympathetically cooled by a laser-cooled atomic ion to near the quantum mechanical ground state of a common trapping potential. More specifically, we present a general framework for simulating the expected photon recoil spectra in regimes where either the natural transition linewidth $\Gamma_t$ of the molecular ion or the spectral width $\Gamma_L$ of the exciting light source exceeds the motional angular frequencies (typically $\sim 2\pi\times 0.1 - 1$ MHz) of the two-ion system. To exemplify the framework, we present two complementary cases: spectroscopy of the broad 3s $^2$S$_{1/2}$ - 3p $^2$P$_{3/2}$ electronic transition ($\Gamma_t/2\pi = 41.8$ MHz) of a single $^{24}$Mg$^+$ ion at $\lambda=279.6$ nm by a narrow laser source ($\Gamma_L/2\pi \lesssim 1$ MHz) and mid-infrared vibrational spectroscopy of the very narrow $|v=0,J=1\rangle$ - $|v'=1,J'=0\rangle$ transition ($\Gamma_t/2\pi = 2.50$ Hz) at $\lambda=6.17$ $\mu$m in the $^1\Sigma^+$ electronic ground state of $^{24}$MgH$^+$ by a broadband laser source ($\Gamma_L/2\pi \gtrsim$ 10 MHz). The atomic ion $^{24}$Mg$^+$ has been picked to introduce a simple system to make comparisons with experimental results while still capturing most of the physics involved in electronic excitations of molecular ions.Comment: 28 pages, 15 figure