Effect of Rotations and Shape Resonances on Photoassociation and Photoacceleration by Ultrashort Infrared Laser Pulses

A quantum dynamical description of an atomic collision pair interacting with the electric field of a short infrared laser pulse is developed. Inelastic processes in the electronic ground state are due to stimulated emission resulting in photoassociation, or absorption leading to photoacceleration. A perturbative approach based on a state space representation is compared with a numerical treatment using a grid representation in coordinate space. Special emphasis is on the role of rotations and, in particular, of shape resonances. It is shown that these quasibound states which are supported by the centrifugal barrier (for J> 0) can be used as initial states to effectively populate a selected bound state with specific vibrational and rotational quantum number (photoassociation), or a partial wave of a scattering state with defined energy and rotational quantum number (photoacceleration). Simulations are carried out for the prototype H + Cl collision pair. Also the effect of averaging over initial conditions (velocity, angular momenta) is investigated for a supersonic beam experiment. For a narrow velocity distribution, we predict the presence of a resonance structure of the association and acceleration probability as a function of the mean collision energy

Josephson effects in dilute Bose-Einstein condensates

We propose an experiment that would demonstrate the ``dc'' and ``ac'' Josephson effects in two weakly linked Bose-Einstein condensates. We consider a time-dependent barrier, moving adiabatically across the trapping potential. The phase dynamics are governed by a ``driven-pendulum'' equation, as in current-driven superconducting Josephson junctions. At a critical velocity of the barrier (proportional to the critical tunneling current), there is a sharp transition between the ``dc'' and ``ac'' regimes. The signature is a sudden jump of a large fraction of the relative condensate population. Analytical predictions are compared with a full numerical solution of the time dependent Gross-Pitaevskii equation, in an experimentally realistic situation.Comment: 4 pages, 1 figur

Characterization of Thin Pixel Sensor Modules Interconnected with SLID Technology Irradiated to a Fluence of 2⋅1015\cdot 10^{15}\,neq_{\mathrm{eq}}/cm2^2

A new module concept for future ATLAS pixel detector upgrades is presented, where thin n-in-p silicon sensors are connected to the front-end chip exploiting the novel Solid Liquid Interdiffusion technique (SLID) and the signals are read out via Inter Chip Vias (ICV) etched through the front-end. This should serve as a proof of principle for future four-side buttable pixel assemblies for the ATLAS upgrades, without the cantilever presently needed in the chip for the wire bonding. The SLID interconnection, developed by the Fraunhofer EMFT, is a possible alternative to the standard bump-bonding. It is characterized by a very thin eutectic Cu-Sn alloy and allows for stacking of different layers of chips on top of the first one, without destroying the pre-existing bonds. This paves the way for vertical integration technologies. Results of the characterization of the first pixel modules interconnected through SLID as well as of one sample irradiated to $2\cdot10^{15}$\,\neqcm{} are discussed. Additionally, the etching of ICV into the front-end wafers was started. ICVs will be used to route the signals vertically through the front-end chip, to newly created pads on the backside. In the EMFT approach the chip wafer is thinned to (50--60)\,$\mu$m.Comment: Proceedings to PSD

Femtosecond Quantum Dynamics of Photoassociation Reactions: The Exciplex Formation of Mercury

A quantum dynamical wave packet description of photoassociation reactions induced by short laser pulses is developed including both vibrational/translation and rotational degrees of freedom. Various levels of approximation (perturbation approach, rotating wave approximation) are discussed. Simulations of the exciplex formation of mercury are performed and related to recent pump-probe experiments by Marvet and Dantus [Chem. Phys. Lett. 245 (1995) 393]. It is shown that in these experiments photoassociation is only due to bound ← free transitions and does not proceed via bound ← bound transitions from a van-der-Waals precursor. The calculated spectra show both vibrational and rotational coherence structure which can be interpreted in terms of quantum beats between different rovibrational states populated during the photoassociation process. The thermally averaged spectra show good qualitative agreement with the experimental data

Stationary Josephson effect in a weak-link between nonunitary triplet superconductors

A stationary Josephson effect in a weak-link between misorientated nonunitary triplet superconductors is investigated theoretically. The non-self-consistent quasiclassical Eilenberger equation for this system has been solved analytically. As an application of this analytical calculation, the current-phase diagrams are plotted for the junction between two nonunitary bipolar $f-$wave superconducting banks. A spontaneous current parallel to the interface between superconductors has been observed. Also, the effect of misorientation between crystals on the Josephson and spontaneous currents is studied. Such experimental investigations of the current-phase diagrams can be used to test the pairing symmetry in the above-mentioned superconductors.Comment: 6 pages and 6 figure

Educational recommendations for the conduct, content and format of EULAR musculoskeletal ultrasound Teaching the Teachers Courses

To produce educational guidelines for the conduct, content and format of theoretical and practical teaching at EULAR musculoskeletal ultrasound (MSUS) Teaching the Teachers (TTT) Courses

Photoassociation of cold atoms with chirped laser pulses: time-dependent calculations and analysis of the adiabatic transfer within a two-state model

This theoretical paper presents numerical calculations for photoassociation of ultracold cesium atoms with a chirped laser pulse and detailed analysis of the results. In contrast with earlier work, the initial state is represented by a stationary continuum wavefunction. In the chosen example, it is shown that an important population transfer is achieved to $\approx 15$ vibrational levels in the vicinity of the v=98 bound level in the external well of the $0_g^-(6s+6p_{3/2})$ potential. Such levels lie in the energy range swept by the instantaneous frequency of the pulse, thus defining a ``photoassociation window''. Levels outside this window may be significantly excited during the pulse, but no population remains there after the pulse. Finally, the population transfer to the last vibrational levels of the ground $a^3\Sigma_u^+$(6s + 6s) is significant, making stable molecules. The results are interpreted in the framework of a two state model as an adiabatic inversion mechanism, efficient only within the photoassociation window. The large value found for the photoassociation rate suggests promising applications. The present chirp has been designed in view of creating a vibrational wavepacket in the excited state which is focussing at the barrier of the double well potential.Comment: 49 pages, 9 figures, submitted to Phys. Rev.

Are there effective interventions to increase physical activity in children and young people? An umbrella review

Background: Obesity and physical inactivity among children and young people are public health concerns. While numerous interventions to promote physical activity are available, little is known about the most effective ones. This study aimed to summarize the existing evidence on interventions that aim to increase physical activity. Methods: A systematic review of reviews was conducted. Systematic reviews and meta-analyses published from January 2010 until November 2017 were identified through PubMed, Scopus and the Cochrane Library. Two reviewers independently assessed titles and abstracts, performed data extraction and quality assessment. Outcomes as level of physical activity and body mass index were collected in order to assess the efficacy of interventions. Results: A total 30 studies examining physical activity interventions met the inclusion criteria, 15 systematic reviews and 15 meta-analyses. Most studies (N = 20) were implemented in the school setting, three were developed in preschool and childcare settings, two in the family context, five in the community setting and one miscellaneous context. Results showed that eight meta-analyses obtained a small increase in physical activity level, out of which five were conducted in the school, two in the family and one in the community setting. Most promising programs had the following characteristics: included physical activity in the school curriculum, were long-term interventions, involved teachers and had the support of families. Conclusion: The majority of interventions to promote physical activity in children and young people were implemented in the school setting and were multicomponent. Further research is needed to investigate nonschool programs

Preliminary definitions for the sonographic features of synovitis in children

Objectives Musculoskeletal ultrasonography (US) has the potential to be an important tool in the assessment of disease activity in childhood arthritides. To assess pathology, clear definitions for synovitis need to be developed first. The aim of this study was to develop and validate these definitions through an international consensus process. Methods The decision on which US techniques to use, the components to be included in the definitions as well as the final wording were developed by 31 ultrasound experts in a consensus process. A Likert scale of 1-5 with 1 indicating complete disagreement and 5 complete agreement was used. A minimum of 80% of the experts scoring 4 or 5 was required for final approval. The definitions were then validated on 120 standardized US images of the wrist, MCP and tibiotalar joints displaying various degrees of synovitis at various ages. Results B-Mode and Doppler should be used for assessing synovitis in children. A US definition of the various components (i.e. synovial hypertrophy, effusion and Doppler signal within the synovium) was developed. The definition was validated on still images with a median of 89% (range 80-100) of participants scoring it as 4 or 5 on a Likert scale. Conclusions US definitions of synovitis and its elementary components covering the entire pediatric age range were successfully developed through a Delphi process and validated in a web-based still images exercise. These results provide the basis for the standardized US assessment of synovitis in clinical practice and research