Isotope shifts of natural Sr+ measured by laser fluorescence in a sympathetically cooled Coulomb crystal

We measured by laser spectroscopy the isotope shifts between naturally-occurring even-isotopes of strontium ions for both the 5s\,\,^2S_{1/2}\to 5p\,\,^2P_{1/2} (violet) and the 4d\,\,^2D_{3/2}\to 5p\,\,^2P_{1/2} (infrared) dipole-allowed optical transitions. Fluorescence spectra were taken by simultaneous measurements on a two-component Coulomb crystal in a linear Paul trap containing $10^3$--$10^4$ laser-cooled Sr$^+$ ions. The isotope shifts are extracted from the experimental spectra by fitting the data with the analytical solution of the optical Bloch equations describing a three-level atom in interaction with two laser beams. This technique allowed us to increase the precision with respect to previously reported data obtained by optogalvanic spectroscopy or fast atomic-beam techniques. The results for the 5s\,\,^2S_{1/2}\to 5p\,\,^2P_{1/2} transition are $\nu_{88}-\nu_{84}=+378(4)$ MHz and $\nu_{88}-\nu_{86}=+170(3)$ MHz, in agreement with previously reported measurements. In the case of the previously unexplored 4d\,\,^2D_{3/2}\to 5p\,\,^2P_{1/2} transition we find $\nu_{88}-\nu_{84}=-828(4)$ MHz and $\nu_{88}-\nu_{86}=-402(2)$ MHz. These results provide more data for stringent tests of theoretical calculations of the isotope shifts of alkali-metal-like atoms. Moreover, they simplify the identification and the addressing of Sr$^+$ isotopes for ion frequency standards or quantum-information-processing applications in the case of multi-isotope ion strings.Comment: 19 pages; 5 figures; accepted on Phys. Rev. A (http://pra.aps.org/

Piégeage et refroidissement d’ions strontium dans des pièges micro-fabriqués.

This thesis is in the general field of quantum information, which proposes to realize infomation processing protocols using laws of quantum mechanics. This work is focused on one of the most promising systems: single ions confined in a radio-frequency trap (Paul trap) and laser-cooled. The purpose of this thesis is to realize the tools (measuring systems and devices) to characterize the "anomalous heating", a phenomenon not fully understood to date, limiting the coherence of ions trapped in planar linear Paul traps.After an introduction to quantum information, principles of trapping and cooling are explained. Then comes a description of improvements realized on an experimental system of ion trapping and cooling. The modeling of trapping electric fields to control the traps is described. A first realisation of trapping in a planar linear Paul trap is described. This realisation allowed for the obtaining planar Coulomb crystals of large size (N> 150). The protocol for producing micro-fabricated linear planar Paul trap of micro-metric size, manufactured in a clean room, is described. Results of ion trapping on such a micro-trap are presented. The last part presents the first results obtained in the team on the anomalous heating, using the so-called "Doppler recoiling" technique.Cette thèse s'inscrit dans le domaine général de l'information quantique, qui propose de réaliser des protocoles de traitement de l'information en utilisant les lois de la mécanique quantique. Ce travail se focalise sur l'un des systèmes les plus prometteurs : les ions uniques confinés dans des pièges radio-fréquence (pièges de Paul) et refroidis par laser. Le but de cette thèse est de mettre en places les outils (systèmes de mesure et échantillons) permettant de caractériser le « chauffage anormal », phénomène à se jour non totalement compris, limitant la cohérence de ions piégés dans des pièges de Paul linéaires planaires.Après une introduction sur l'information quantique, les principes de piégeage et de refroidissement sont expliqués. Vient ensuite une description des améliorations effectuées sur un système expérimental de piégeage et de refroidissement d'ions. La modélisation des champs électriques de piégeage permettant de contrôler les pièges est présentée. Une première réalisation de piégeage sur un piège de Paul linéaire planaire est décrite. Celle-ci à permis l'obtention de cristaux de Coulomb planaires de grandes dimension (N>150). Le protocole de réalisation de pièges de Paul linéaires planaire de taille micro-métriques, fabriqués en salle blanche, est décrit. Les résultats du piégeage d'ions sur de tels micro-pièges sont présentés. Cette dernière partie présente des premiers résultats de l'équipe concernant le chauffage anormal, utilisant la technique dite du « Doppler recoiling »

A Spatial Characterization of the Sagittarius Dwarf Galaxy Tidal Tails

We measure the spatial density of F turnoff stars in the Sagittarius dwarf tidal stream, from Sloan Digital Sky Survey (SDSS) data, using statistical photometric parallax. We find a set of continuous, consistent parameters that describe the leading Sgr stream's position, direction, and width for 15 stripes in the North Galactic Cap, and 3 stripes in the South Galactic Cap. We produce a catalog of stars that has the density characteristics of the dominant leading Sgr tidal stream that can be compared with simulations. We find that the width of the leading (North) tidal tail is consistent with recent triaxial and axisymmetric halo model simulations. The density along the stream is roughly consistent common disruption models in the North, but possibly not in the South. We explore the possibility that one or more of the dominant Sgr streams has been mis-identified, and that one or more of the `bifurcated' pieces is the real Sgr tidal tail, but we do not reach definite conclusions. If two dwarf progenitors are assumed, fits to the planes of the dominant and `bifurcated' tidal tails favor an association of the Sgr dwarf spheroidal galaxy with the dominant Southern stream and the `bifurcated' stream in the North. In the North Galactic Cap, the best fit Hernquist density profile for the smooth component of the stellar halo is oblate, with a flattening parameter q = 0.53, and a scale length of r_0 = 6.73. The Southern data for both the tidal debris and the smooth component of the stellar halo do not match the model fits to the North, although the stellar halo is still overwhelmingly oblate. Finally, we verify that we can reproduce the parameter fits on the asynchronous Milkyway@home volunteer computing platform.Comment: 35 pages, 8 figures, 9 tables. Accepted for publication in The Astrophysical Journa

Current opinions regarding care of the mature pediatric urology patient

Introduction With continued improvements in pediatric urology care of patients with complex congenital genitourinary conditions, many survive into adulthood. This fact has created a challenging situation of transitioning from pediatric to adult care. Establishing long-term follow-up with appropriate specialists is a critical part of a successful transition to adulthood for this population. Objective This study sought to elucidate current practices and opinions regarding the management of adult complex genitourinary patients by pediatric urologists, in order to determine if a consensus for adult care exists. Study design An anonymous, 15-question online survey was created to address practice patterns and opinions regarding the transition of care of complex genitourinary patients. An invitation to participate was distributed via email to 200 pediatric urologists who were members of the American Urological Association. Complex genitourinary patients were defined broadly as those with a history of: spina bifida, bladder exstrophy, cloacal exstrophy, cloacal anomalies, posterior urethral valves or disorders of sex development. Fisher's exact test was used for analysis. Results The response rate was 31.0% (62/200). Two-thirds (67.7%) cared for adults with complex genitourinary conditions. Overall, 51.6% of pediatric urologists felt that general urologists best follow adult patients, but only 6.5% recommended this for patients with prior complex genitourinary reconstruction (P < 0.001). Instead, the majority (80.6%) felt that a pediatric or adult urologist with an interest and training in adolescent/transitional urology who routinely performs such procedures would provide optimal care. Follow-up by a primary care physician alone was not recommended. Recommendations did not change if patients had developmental delay or lived independently (P = 0.47 and P = 0.72, respectively). Overall, 69.4% would refer mature complex genitourinary patients to a urologist with interest and training in adolescent/transitional urology, if one was available. However, only 45.2% had such an individual available in their practice (P < 0.001). Discussion In the present study, the opinions of pediatric urologists regarding optimal providers of long-term follow-up for mature complex genitourinary patients were presented. While the results may not represent the views of the entire pediatric urology community, responses from motivated individuals with a particular interest in transition care may be especially valuable. Although the present study did not outline a mechanism for improving transitional care, it offered valuable information on prevailing opinions in this area. Finally, the opinions of mostly North American Pediatric Urologists were presented, which may not apply to other healthcare settings. Conclusions Pediatric urologists appeared to be virtually unanimous in recommending that urologists provide the most appropriate long-term follow-up of patients with congenital genitourinary conditions. Specifically, 80% recommended that patients with prior complex surgical reconstruction be followed by a urologist with specific interest, training and experience in the area of transitional urology. The data suggest that this may be an unmet need of these specialists and may signify the need for specific training in the care of such patients

Pediatric Sacral Nerve Stimulator Explanation due to Complications or Cure: A Survival Analysis

Introduction Historically, there have been few treatment options for children with severe, refractory bladder and bowel dysfunction (BBD). Sacral neuromodulation (SNM) continues to show promising results in this challenging pediatric population with recalcitrant lower urinary tract symptoms. At our institution, we have begun offering explantation to those with persistent improvement after >6 months of having device turned off. We hypothesized that 1.) SNM explantation for cure increases with extended follow-up, and 2.) those explanted for cure would have improved symptoms and quality of life when compared to those explanted for complication. Materials & Methods We retrospectively reviewed all consecutive patients <18 years old who underwent SNM placements at our institution (2012-2017). We excluded those without the second stage procedure. Reasons for device explantation were categorized as: cure (resolution of symptoms with the device turned off for at least 6 months), or a complication (e.g. infection, need for MRI, or pain). Non-parametric tests and survival analysis were used for analysis to account for differential follow-up time. Of those explanted, surveys were electronically sent to assess BBD severity, and overall quality of life. Results Of 67 children who underwent a first stage procedure, 62 (92.5%) underwent a second stage procedure. 61 met inclusion criteria (68.9% female, 29.5 % with previous filum section, median age at implantation 10.3 years old). During follow-up (median 2.3 years), 12 patients (19.7 %) had the SNM exchanged/revised due to lead fracture/breakage and return of urinary symptoms. To date, 50 patients remain with their SNM implanted, and 11 have been explanted. Adjusting for follow-up time, the risk of explantation was 6.5% at 2 years (2.2% for cure, 4.3% for complications) (Figure 1). Explantation increased to 24.5% at 3 years (16.5% for cure, 8.0% for complications) and 40.4% at 4 years (32.4% for cure, 8.0% for complications). Questionnaires were collected on patients post explant (median 2.2 years), with improvement in those explanted for cure compared to complication (Figure 2). Discussion SNM explantation for cure is a novel concept previously not described in the literature. Limitations of this study include the relatively small numbers, and lack of objective data in the cohort that remains with SNM device implanted. Conclusion SNM is a safe, viable option for the pediatric patient with refractory bladder dysfunction. Furthermore, SNM explantation for cure is an option with increasing likelihood after two years

Validation and Preliminary Results of the Parental Assessment of Children's External Genitalia Scale for Females (PACE-F) for Girls With Congenital Adrenal Hyperplasia

Objective To validate a parental assessment of children's external genitalia scale for females (PACE-F) for girls with congenital adrenal hyperplasia (CAH) by adapting the validated adult female genital self-image scale. Methods PACE-F was administered to parents of girls (Tanner 1, 2 months-12 years) with and without CAH. Final questions were determined by clinical relevance and psychometric properties (scores: 0-100). A reference range was established using 95% confidence interval among controls. Age-matched controls were compared to girls with CAH (1) <4 years old before and after female genital reconstruction surgery (FGRS), and (2) 4-12-year olds after FGRS. Nonparametric statistics were used. Results Participants included 56 parents of 41 girls with CAH (median 3.9 years old, 97.6% FGRS) and 139 parents of 130 girls without CAH. Face and content validity was established by families, experts, and factor analysis. Internal consistency was high (Cronbach's alpha: 0.83). Population reference score range was 66.7-100. Ten consecutive girls had pre- and post-FGRS PACE-F scores. All scores improved at 4 months after surgery and all preoperative scores were below reference range and lower than controls (P = .0001). All postoperative scores were within reference range, no different from controls (P = .18). Scores for girls with CAH after FGRS aged 4-12 years were no different from controls (100.0 vs 88.9, P = .77) and 90.0% were in reference range, as expected (P = .99). Conclusion We present a validated instrument for parental assessment of genital appearance in girls with CAH. We demonstrate improved parent-reported appearance after FGRS, with scores similar to age-matched controls

Automation of large scale transient protein expression in mammalian cells

Traditional mammalian expression systems rely on the time-consuming generation of stable cell lines; this is difficult to accommodate within a modern structural biology pipeline. Transient transfections are a fast, cost-effective solution, but require skilled cell culture scientists, making man-power a limiting factor in a setting where numerous samples are processed in parallel. Here we report a strategy employing a customised CompacT SelecT cell culture robot allowing the large-scale expression of multiple protein constructs in a transient format. Successful protocols have been designed for automated transient transfection of human embryonic kidney (HEK) 293T and 293S GnTI⁻ cells in various flask formats. Protein yields obtained by this method were similar to those produced manually, with the added benefit of reproducibility, regardless of user. Automation of cell maintenance and transient transfection allows the expression of high quality recombinant protein in a completely sterile environment with limited support from a cell culture scientist. The reduction in human input has the added benefit of enabling continuous cell maintenance and protein production, features of particular importance to structural biology laboratories, which typically use large quantities of pure recombinant proteins, and often require rapid characterisation of a series of modified constructs. This automated method for large scale transient transfection is now offered as a Europe-wide service via the P-cube initiative

A Spatial Characterization of the Saggitarius Dwarf Galaxy Tidal Tails

We measure the spatial density of F turnoff stars in the Sagittarius dwarf tidal stream, from Sloan Digital Sky Survey data, using statistical photometric parallax. We find a set of continuous, consistent parameters that describe the leading Sgr stream\u27s position, direction, and width for 15 stripes in the north Galactic cap, and three stripes in the south Galactic cap. We produce a catalog of stars that has the density characteristics of the dominant leading Sgr tidal stream that can be compared with simulations. We find that the width of the leading (north) tidal tail is consistent with recent triaxial and axisymmetric halo model simulations. The density along the stream is roughly consistent with common disruption models in the north, but possibly not in the south. We explore the possibility that one or more of the dominant Sgr streams has been misidentified, and that one or more of the bifurcated pieces is the real Sgr tidal tail, but we do not reach definite conclusions. If two dwarf progenitors are assumed, fits to the planes of the dominant and bifurcated tidal tails favor an association of the Sgr dwarf spheroidal galaxy with the dominant southern stream and the bifurcated stream in the north. In the north Galactic cap, the best fit Hernquist density profile for the smooth component of the stellar halo is oblate, with a flattening parameter q = 0.53, and a scale length of r 0 = 6.73. The southern data for both the tidal debris and the smooth component of the stellar halo do not match the model fits to the north, although the stellar halo is still overwhelmingly oblate. Finally, we verify that we can reproduce the parameter fits on the asynchronous MilkyWay@home volunteer computing platform