Ultrafast laser inscription of mid-IR directional couplers for stellar interferometry

We report the ultrafast laser fabrication and mid-IR characterization (3.39 microns) of four-port evanescent field directional couplers. The couplers were fabricated in a commercial gallium lanthanum sulphide glass substrate using sub-picosecond laser pulses of 1030 nm light. Straight waveguides inscribed using optimal fabrication parameters were found to exhibit propagation losses of 0.8 dB/cm. A series of couplers were inscribed with different interaction lengths, and we demonstrate power splitting ratios of between 8% and 99% for mid-IR light with a wavelength of 3.39 microns. These results clearly demonstrate that ultrafast laser inscription can be used to fabricate high quality evanescent field couplers for future applications in astronomical interferometry.Comment: 4 pages, 4 figure

Quantum control in foundational experiments

We describe a new class of experiments designed to probe the foundations of quantum mechanics. Using quantum controlling devices, we show how to attain a freedom in temporal ordering of the control and detection of various phenomena. We consider wave-particle duality in the context of quantum-controlled and the entanglement-assisted delayed-choice experiments. Then we discuss a quantum-controlled CHSH experiment and measurement of photon's transversal position and momentum in a single set-up.Comment: Contribution to the Proceedings of the workshop Horizons of Quantum Physics, Taipei, 14-18.10.2012. Published version: two new authors, modified and streamlined presentation, new section on quantum control in complementary position/momentum measurement

Integrated optics prototype beam combiner for long baseline interferometry in the L and M bands

In the last few years, integrated optics (IO) beam combiners have facilitated the emergence of 4-telescope interferometers such as PIONIER or GRAVITY, boosting the imaging capabilities of the VLTI. However, the spectral range beyond 2.2microns is not ideally covered by the conventional silica based IO. Here, we propose to consider new laser-written IO prototypes made of GLS glasses, a material that permits access to the mid-infrared spectral regime. Our goal is to conduct a full characterization of our mid-IR IO 2-telescope coupler in order to measure the performance levels directly relevant for long-baseline interferometry. We focus in particular on the exploitation of the L and M astronomical bands. We use a dedicated Michelson-interferometer setup to perform Fourier Transform spectroscopy on the coupler and measure its broadband interferometric performance. We also analyze the polarization properties of the coupler, the differential dispersion and phase degradation as well as the modal behavior and the total throughput. We measure broadband interferometric contrasts of 94.9% and 92.1% for unpolarized light in the L and M bands. Spectrally integrated splitting ratios are close to 50% but show chromatic dependence over the considered bandwidths. Additionally, the phase variation due to the combiner is measured and does not exceed 0.04rad and 0.07rad across the band L and M band, respectively. The total throughput of the coupler including Fresnel and injection losses from free-space is 25.4%. The laser-written IO GLS prototype combiners prove to be a reliable technological solution with promising performance for mid-infrared long-baseline interferometry. In the next steps, we will consider more advanced optical functions as well as a fiber-fed input and revise the optical design parameters in order the further enhance the total throughput and achromatic behavior

Testing General Relativity with Current Cosmological Data

Deviations from general relativity, such as could be responsible for the cosmic acceleration, would influence the growth of large scale structure and the deflection of light by that structure. We clarify the relations between several different model independent approaches to deviations from general relativity appearing in the literature, devising a translation table. We examine current constraints on such deviations, using weak gravitational lensing data of the CFHTLS and COSMOS surveys, cosmic microwave background radiation data of WMAP5, and supernova distance data of Union2. Markov Chain Monte Carlo likelihood analysis of the parameters over various redshift ranges yields consistency with general relativity at the 95% confidence level.Comment: 11 pages; 7 figures; typographical errors corrected; this is the published versio

A new baenid turtle from the early Paleocene (Torrejonian) of New Mexico and a species-level phylogenetic analysis of Baenidae

New cranial and postcranial material of the baenid turtle Neurankylus from the Paleocene Nacimiento Formation (Torrejonian NALMA) of northwestern New Mexico represents a new species, Neurankylus torrejonensis. The material consists of a fragmented but mostly complete skull, a partial carapace and plastron, portions of both humeri, a partial pelvis, a complete right femur, and a distal phalanx. The small, undivided cervical scale, wide vertebrals, complete ring of marginals, and large size (carapace length 520 mm) diagnose the new taxon as belonging to Neurankylus. The narrow fifth vertebral scale and scalloped posterior shell margin reveal affinities with Neurankylus baueri Gilmore, 1916, which is known from Campanian sediments in New Mexico and Utah. The holotype of Neurankylus torrejonensis is the youngest known specimen of the Neurankylus lineage, which is known to reach at least back to the Late Cretaceous (Santonian). A nearly complete species-level analysis of baenids confirms the basal placement of Neurankylus outside of Baenodda and the split of Baenodda into two primary subclades, herein named Palatobaeninae and Eubaeninae

Early Inflammation Disorder in Neonatal Calves

In the present study, 30 Holstein calves were acquired at birth and were randomly subjected to one of six treatments. One treatment group was colostrum deprived (CD) and five other treatment groups were fed colostrum replacer (CR). Of the five CR groups, one group was not further supplemented (CR), one received vitamin A (CR-A), one received vitamin D (CR-D), one received vitamin E (CR-E), and one received vitamins A, D, and E (CR-ADE). Additionally, all calves were inoculated with Mycobacterium avium, subsp. paratuberculosis on d 1 and d 3 of age. One d after birth, CD calves exhibited lower IgG1, haptoglobin, and serum amyloid A concentrations in serum compared with the other five CR groups. These findings point to an endogenous early inflammation disorder in calves that are not fed colostrum

Experiments with a Malkus-Lorenz water wheel: Chaos and Synchronization

We describe a simple experimental implementation of the Malkus-Lorenz water wheel. We demonstrate that both chaotic and periodic behavior is found as wheel parameters are changed in agreement with predictions from the Lorenz model. We furthermore show that when the measured angular velocity of our water wheel is used as an input signal to a computer model implementing the Lorenz equations, high quality chaos synchronization of the model and the water wheel is achieved. This indicates that the Lorenz equations provide a good description of the water wheel dynamics.Comment: 12 pages, 7 figures. The following article has been accepted by the American Journal of Physics. After it is published, it will be found at http://scitation.aip.org/ajp

Protector and friend: Turning points and discursive constructions of the stepparent role

Objective: To understand turning points (TPs) in the development of positive stepparent–stepchild communication and relationships. Background: Scholars stress the importance of communication in co-constructing healthy stepparent–stepchild relationships. The researchers focused on positive stepparenting via understanding transformational turning point (TP) events across time. Research questions explored how stepparents with an overall positive relationship with a stepchild characterize TPs and the discursive constructions of the stepparent role. Method: The team analyzed 877 pages of data from 37 in-depth interviews with stepparents who described self-identified TP events, reflected in visual graphs of 279 TPs. Results: Data were coded into 11 TP types, focused on structural and role changes for stepparents, co-constructed over time. The top three TP types were changes in household composition, communicating support through offering protection and being present/available, and role change, most frequently by functioning as a parent versus friend. All the TPs highlight discursive work to forge positive stepparenting roles. Conclusions: The findings extend earlier studies of stepchildren’s experiences and communication practices that ground resilience to manage relational resources through investments of quality time and enactment of social support. Implications: Applications suggest support for stepparents to have quality interactions with stepchildren and training to develop healthy communication practices and facilitate resilience

Asteroseismology of the Hyades with K2: first detection of main-sequence solar-like oscillations in an open cluster

The Hyades open cluster was targeted during Campaign 4 (C4) of the NASA K2 mission, and short-cadence data were collected on a number of cool main-sequence stars. Here, we report results on two F-type stars that show detectable oscillations of a quality that allows asteroseismic analyses to be performed. These are the first ever detections of solar-like oscillations in main-sequence stars in an open cluster.Comment: 12 pages, 8 figures, 2 tables; accepted for publication in MNRA

Characterization of three-body loss in 166Er and optimized production of large Bose-Einstein condensates

Ultracold gases of highly magnetic lanthanide atoms have enabled the realization of dipolar quantum droplets and supersolids. However, future studies could be limited by the achievable atom numbers and hindered by high three-body loss rates. Here we study density-dependent atom loss in an ultracold gas of 166Er for magnetic fields below 4 G, identifying six previously unreported, strongly temperature-dependent features. We find that their positions and widths show a linear temperature dependence up to at least 15 µK. In addition, we observe a weak, polarization-dependent shift of the loss features with the intensity of the light used to optically trap the atoms. This detailed knowledge of the loss landscape allows us to optimize the production of dipolar Bose-Einstein condensates with more than 2 × 105 atoms and points towards optimal strategies for the study of large-atom-number dipolar gases in the droplet and supersolid regimes