184 research outputs found
Unconventional superfluid order in the -band of a bipartite optical square lattice
We report on the first observation of bosons condensed into the energy minima
of an -band of a bipartite square optical lattice. Momentum spectra indicate
that a truly complex-valued staggered angular momentum superfluid order is
established. The corresponding wave function is composed of alternating local
-orbits and local -orbits residing in the deep
and shallow wells of the lattice, which are arranged as the black and white
areas of a checkerboard. A pattern of staggered vortical currents arises, which
breaks time reversal symmetry and the translational symmetry of the lattice
potential. We have measured the populations of higher order Bragg peaks in the
momentum spectra for varying relative depths of the shallow and deep lattice
wells and find remarkable agreement with band calculations.Comment: 4 pages, 3 figure
Intracavity Raman scattering couples soliton molecules with terahertz phonons
Ultrafast atomic vibrations mediate heat transport, serve as fingerprints for chemical bonds and drive phase transitions in condensed matter systems. Light pulses shorter than the atomic oscillation period can not only probe, but even stimulate and control collective excitations. In general, such interactions are performed with free-propagating pulses. Here, we demonstrate intra-cavity excitation and time-domain sampling of coherent optical phonons inside an active laser oscillator. Employing real-time spectral interferometry, we reveal that Terahertz beats of Raman-active optical phonons are the origin of soliton bound-states – also termed “Soliton molecules” – and we resolve a coherent coupling mechanism of phonon and intra-cavity soliton motion. Concurring electronic and nuclear refractive nonlinearities generate distinct soliton trajectories and, effectively, enhance the time-domain Raman signal. We utilize the intrinsic soliton motion to automatically perform highspeed Raman spectroscopy of the intra-cavity crystal. Our results pinpoint the impact of Raman-induced soliton interactions in crystalline laser media and microresonators, and offer unique perspectives toward ultrafast nonlinear phononics by exploiting the coupling of atomic motion and solitons inside a cavity
AmbiGaze:direct control of ambient devices by gaze
Eye tracking offers many opportunities for direct device control in smart environments, but issues such as the need for calibration and the Midas touch problem make it impractical. In this paper, we propose AmbiGaze, a smart environment that employs the animation of targets to provide users with direct control of devices by gaze only through smooth pursuit tracking. We propose a design space of means of exposing functionality through movement and illustrate the concept through four prototypes. We evaluated the system in a user study and found that AmbiGaze enables robust gaze-only interaction with many devices, from multiple positions in the environment, in a spontaneous and comfortable manner
Use of computed tomography and mechanical CPR in cardiac arrest to confirm pulmonary embolism: a case study
Precise therapeutic decision-making is vital in managing out-of-hospital cardiac arrest. We present an interesting approach where suspected pulmonary embolism could be confirmed by early computed tomography in cardiac arrest. Chest compressions were performed automatically by mechanical devices also during the acquisition of computed tomography data and subsequent thrombolysis. Resume La precision des decisions relatives au traitement est d'importance > dans la prise en charge des arrets cardiaques extrahospitaliers. Sera presentee ici une intervention interessante, qui a permis de confirmer, par une tomodensitometrie (TDM) precoce, une embolie pulmonaire presumee chez une patiente en etat d'arret cardiaque. Les compressions thoraciques, realisees automatiquement par un appareil mecanique se sont poursuivies durant l'acquisition des donnees de la TDM et le traitement thrombolytique qui s'en est suivi
Incidence of delayed and missed diagnoses in whole-body multidetector CT in patients with multiple injuries after trauma
Background: Whole-body CT (WBCT) is the imaging modality of choice during the initial diagnostic work-up of multiple injured patients in order to identify serious injuries and initiate adequate treatment immediately. However, delayed diagnosed or even missed injuries have been reported frequently ranging from 1.3% to 47%. Purpose: To highlight commonly missed lesions in WBCT of patients with multiple injuries. Material and Methods: A total of 375 patients (age 42.8 +/- 17.9 years, ISS 26.6 +/- 17.0) with a WBCT (head to symphysis) were included. The final CT report was compared with clinical and operation reports. Discrepant findings were recorded and grouped as relevant and non-relevant to further treatment. In both groups, an experienced trauma radiologist read the CT images retrospectively, whether these lesions were missed or truly not detectable. Results: In 336 patients (89.6%), all injuries in the regions examined were diagnosed correctly in the final reports of the initial CT. Forty-eight patients (12.8%) had injuries in regions of the body that were not included in the CT. Fourteen patients (3.7%) had injuries that did not require further treatment. Twenty-five patients (6.7%) had injuries that required further treatment. With secondary interpretation, 85.4% of all missed lesions could be diagnosed in retrospect from the primary CT data-set. Small pancreatic and bowel contusions were identified as truly non-detectable. Conclusion: In multiple traumas, only a few missed injuries in initial WBCT reading are clinically relevant. However, as the vast majority of these injuries are detectable, the radiologist has to be alert for commonly missed findings to avoid a delayed diagnosis
Removal of hydrogen from Ti VT 1-0 under action of accelerated electrons
The process of hydrogen removal from titanium of VT1-0 grade under the action of accelerated electrons has been studied experimentally. The irradiation was carried out by an electron beam with energies of 25-40 keV during 15-60 min. The information on the hydrogen content in samples from titanium of VT1-0 grade has been obtained both before and after irradiation with accelerated electrons. The activation energy of hydrogen desorption from titanium has been calculated. It was found that the increase of the time and the energy of an irradiation lead to the decrease of the residual hydrogen content in the titanium samples
Orbital superfluidity in the -band of a bipartite optical square lattice
The successful emulation of the Hubbard model in optical lattices has
stimulated world wide efforts to extend their scope to also capture more
complex, incompletely understood scenarios of many-body physics. Unfortunately,
for bosons, Feynmans fundamental "no-node" theorem under very general
circumstances predicts a positive definite ground state wave function with
limited relevance for many-body systems of interest. A promising way around
Feynmans statement is to consider higher bands in optical lattices with more
than one dimension, where the orbital degree of freedom with its intrinsic
anisotropy due to multiple orbital orientations gives rise to a structural
diversity, highly relevant, for example, in the area of strongly correlated
electronic matter. In homogeneous two-dimensional optical lattices, lifetimes
of excited bands on the order of a hundred milliseconds are possible but the
tunneling dynamics appears not to support cross-dimensional coherence. Here we
report the first observation of a superfluid in the -band of a bipartite
optical square lattice with -orbits and -orbits arranged in a
chequerboard pattern. This permits us to establish full cross-dimensional
coherence with a life-time of several ten milliseconds. Depending on a small
adjustable anisotropy of the lattice, we can realize real-valued striped
superfluid order parameters with different orientations or a
complex-valued order parameter, which breaks time reversal
symmetry and resembles the -flux model proposed in the context of high
temperature superconductors. Our experiment opens up the realms of orbital
superfluids to investigations with optical lattice models.Comment: 5 pages, 5 figure
Data assimilation in slow-fast systems using homogenized climate models
A deterministic multiscale toy model is studied in which a chaotic fast
subsystem triggers rare transitions between slow regimes, akin to weather or
climate regimes. Using homogenization techniques, a reduced stochastic
parametrization model is derived for the slow dynamics. The reliability of this
reduced climate model in reproducing the statistics of the slow dynamics of the
full deterministic model for finite values of the time scale separation is
numerically established. The statistics however is sensitive to uncertainties
in the parameters of the stochastic model. It is investigated whether the
stochastic climate model can be beneficial as a forecast model in an ensemble
data assimilation setting, in particular in the realistic setting when
observations are only available for the slow variables. The main result is that
reduced stochastic models can indeed improve the analysis skill, when used as
forecast models instead of the perfect full deterministic model. The stochastic
climate model is far superior at detecting transitions between regimes. The
observation intervals for which skill improvement can be obtained are related
to the characteristic time scales involved. The reason why stochastic climate
models are capable of producing superior skill in an ensemble setting is due to
the finite ensemble size; ensembles obtained from the perfect deterministic
forecast model lacks sufficient spread even for moderate ensemble sizes.
Stochastic climate models provide a natural way to provide sufficient ensemble
spread to detect transitions between regimes. This is corroborated with
numerical simulations. The conclusion is that stochastic parametrizations are
attractive for data assimilation despite their sensitivity to uncertainties in
the parameters.Comment: Accepted for publication in Journal of the Atmospheric Science
Identification of Drosophila centromere associated proteins by quantitative affinity purification-mass spectrometry
AbstractCentromeres of higher eukaryotes are epigenetically defined by the centromere specific histone H3 variant CENP-ACID. CENP-ACID builds the foundation for the assembly of a large network of proteins. In contrast to mammalian systems, the protein composition of Drosophila centromeres has not been comprehensively investigated. Here we describe the proteome of Drosophila melanogaster centromeres as analyzed by quantitative affinity purification-mass spectrometry (AP-MS). The AP-MS input chromatin material was prepared from D. melanogaster cell lines expressing CENP-ACID or H3.3 fused to EGFP as baits. Centromere chromatin enriched proteins were identified based on their relative abundance in CENP-ACID–GFP compared to H3.3-GFP or mock affinity-purifications. The analysis yielded 86 proteins specifically enriched in centromere chromatin preparations.The data accompanying the manuscript on this approach (Barth et al., 2015, Proteomics 14:2167-78, DOI: 10.1002/pmic.201400052) has been deposited to the ProteomeXchange Consortium (http://www.proteomexchange.org) via the PRIDE partner repository with the dataset identifier PXD000758
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