An ultra-bright atom laser

We present a novel, ultra-bright atom-laser and ultra-cold thermal atom beam. Using rf-radiation we strongly couple the magnetic hyperfine levels of 87Rb atoms in a magnetically trapped Bose-Einstein condensate. At low rf-frequencies gravity opens a small hole in the trapping potenital and a well collimated, extremely bright atom laser emerges from just below the condensate. As opposed to traditional atom lasers based on weak coupling, this technique allows us to outcouple atoms at an arbitrarily large rate. We demonstrate an increase in flux per atom in the BEC by a factor of sixteen compared to the brightest quasi-continuous atom laser. Furthermore, we produce by two orders of magnitude the coldest thermal atom beam to date (200 nK).Comment: 20 pages, 9 figures, supplementary material online at http://www.bec.g

Cell type-specific encoding and routing of sensory information in mouse primary somatosensory cortex during behavior

Information is processed in the mammalian cortex through both long-range and local circuits. Our understanding of how neurons in cortical circuits are arranged to process and route these sensory, motor, associative signals during behavior is limited. Here, \textit{in vivo} labelling and recording of projection neurons between primary and secondary mouse somatosensory cortex (S1 and S2) revealed shared and distinct information transfer between areas during a during context-dependent sensory processing task. Development and application of the novel CRACK platform to link the function and transcriptomic identity of hundreds of cells simultaneously revealed specific roles for molecular cell types within S1. The sensory-driven excitatory cell type Baz1a was found to maintain stimulus responsiveness during altered sensory experience and showed increased anatomical connectivity to somatostatin-expressing cells. This suggests Baz1a cells are situated to bias S1 towards bottom-up sensory inputs, answering a mechanistic question as to how the cortex can negotiate between feedforward and feedback input based on need. Together, these findings enhance our understanding of the cellular components and their roles in S1

Stark shift of the A2Π1/2A^2\Pi_{1/2} state in 174^{174}YbF

We have measured the Stark shift of the $A^2\Pi_{1/2} - X^2\Sigma^+$ transition in YbF. We use a molecular beam triple resonance method, with two laser transitions acting as pump and probe, assisted by an rf transition that tags a single hyperfine transition of the X state. After subtracting the known ground state Stark shift, we obtain a value of $70.3(1.5)$Hz/(V/cm)$^2$ for the static electric polarizability of the state $A^2\Pi_{1/2}(J=1/2,f)$. From this we calculate a value $\mu_e=2.46(3)$D for the electric dipole moment of the $A^2\Pi_{1/2}(v=0)$ state.Comment: 3 pages, 2 figure

Scalable Probabilistic Forecasting in Retail with Gradient Boosted Trees: A Practitioner's Approach

The recent M5 competition has advanced the state-of-the-art in retail forecasting. However, we notice important differences between the competition challenge and the challenges we face in a large e-commerce company. The datasets in our scenario are larger (hundreds of thousands of time series), and e-commerce can afford to have a larger assortment than brick-and-mortar retailers, leading to more intermittent data. To scale to larger dataset sizes with feasible computational effort, firstly, we investigate a two-layer hierarchy and propose a top-down approach to forecasting at an aggregated level with less amount of series and intermittency, and then disaggregating to obtain the decision-level forecasts. Probabilistic forecasts are generated under distributional assumptions. Secondly, direct training at the lower level with subsamples can also be an alternative way of scaling. Performance of modelling with subsets is evaluated with the main dataset. Apart from a proprietary dataset, the proposed scalable methods are evaluated using the Favorita dataset and the M5 dataset. We are able to show the differences in characteristics of the e-commerce and brick-and-mortar retail datasets. Notably, our top-down forecasting framework enters the top 50 of the original M5 competition, even with models trained at a higher level under a much simpler setting

Franck-Condon Factors and Radiative Lifetime of the A^{2}\Pi_{1/2} - X^{2}\Sigma^{+} Transition of Ytterbium Monoflouride, YbF

The fluorescence spectrum resulting from laser excitation of the A^{2}\Pi_{1/2} - X^{2}\Sigma^{+} (0,0) band of ytterbium monofluoride, YbF, has been recorded and analyzed to determine the Franck-Condon factors. The measured values are compared with those predicted from Rydberg-Klein-Rees (RKR) potential energy curves. From the fluorescence decay curve the radiative lifetime of the A^{2}\Pi_{1/2} state is measured to be 28\pm2 ns, and the corresponding transition dipole moment is 4.39\pm0.16 D. The implications for laser cooling YbF are discussed.Comment: 5 pages, 5 figure

Grégoire D. Ziakas, Ὁ Ἀριστστέλης στήν ἀραβική παράδση [Aristote dans la tradition arabe]

Condylis Hélène. Grégoire D. Ziakas, Ὁ Ἀριστστέλης στήν ἀραβική παράδση [Aristote dans la tradition arabe]. In: Revue Philosophique de Louvain. Quatrième série, tome 81, n°52, 1983. pp. 691-693

Sthephanites Kai Ichnelates : traduction grecque (XIème siècle) du recueil de fables arabes Kitab Kalila Wa-Dimna d'Ibn Al-Muqaffa (VIIIème siècle)

Thèse de doctorat -- Université catholique de Louvain, 198

NOANT: the natural ontological attitude of actor-network theory

© 1998 David CondylisFrom Introduction: Philosophers and others are divided over the question of whether Bruno Latour’s actor/actant-network theory (ANT) amounts to an antirealist or a realist understanding of science. What seemingly all protagonists share, though, is the taken-for-granted assumption that Latour is making deep metaphysical claims about science. I reject both sides of the divide through questioning this assumption. I do this through an exercise in parallelism. I parallel the approach in Latour’s (1988; 1988a) studies of Einstein and Pasteur, with Arthur Fine’s (1986/1996) approach articulated in his conceptual biography of Einstein: The Shaky Game: Einstein Realism and the Quantum Theory. The historiography of science Fine delineates as the Natural Ontological Attitude (NOA), is specifically engineered as an ametaphysical alternative to the extremes of both realism and antirealism. First, I document and argue for the thesis that NOA generally sums up Latour’s historiography of science. This is what I term the NOANT thesis. On its strongest construction, the NOANT thesis is descriptive. It has it that all the ANT’s historiography amounts to is ametaphysical NOA. On its weakest construction however, it is prescriptive. On this construction, the NOANT thesis has it that all the ANT should amount to NOA. Whatever Latour’s philosophical inclinations, the weaker reading on ANT has it that attempting to reconstruct ANT most charitably, means holding Latour to what – taken together – are the NOA-indicative statements scattered throughout his corpus. However, I frame my presentation and argument in terms of the stronger construction. If I fail to make plausible my case that NOANT is characteristic on ANT, nevertheless I will still have contributed to a case for the weaker construction. That is: ANT, to coherently function, should be simply understood in terms of NOA’s open, ametaphysical ‘logic.

Measuring the electron electric dipole moment using supersonic YbF

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