Translations and dynamics

We analyze the role played by local translational symmetry in the context of gauge theories of fundamental interactions. Translational connections and fields are introduced, with special attention being paid to their universal coupling to other variables, as well as to their contributions to field equations and to conserved quantities.Comment: 22 Revtex pages, no figures. Published version with minor correction

Cooperative subwavelength molecular quantum emitter arrays

Dipole-coupled subwavelength quantum emitter arrays respond cooperatively to external light fields as they may host collective delocalized excitations (a form of excitons) with super- or subradiant character. Deeply subwavelength separations typically occur in molecular ensembles, where in addition to photon-electron interactions, electron-vibron couplings and vibrational relaxation processes play an important role. We provide analytical and numerical results on the modification of super- and subradiance in molecular rings of dipoles including excitations of the vibrational degrees of freedom. While vibrations are typically considered detrimental to coherent dynamics, we show that molecular dimers or rings can be operated as platforms for the preparation of long-lived dark superposition states aided by vibrational relaxation. In closed ring configurations, we extend previous predictions for the generation of coherent light from ideal quantum emitters to molecular emitters, quantifying the role of vibronic coupling onto the output intensity and coherence

Electromagnetically induced transparency in cold 85Rb atoms trapped in the ground hyperfine F = 2 state

We report electromagnetically induced transparency (EIT) in cold 85Rb atoms, trapped in the lower hyperfine level F = 2, of the ground state 5$^{2}S_{1/2}$ (Tiwari V B \textit{et al} 2008 {\it Phys. Rev.} A {\bf 78} 063421). Two steady state $\Lambda$-type systems of hyperfine energy levels are investigated using probe transitions into the levels F$^{\prime}$ = 2 and F$^{\prime}$ = 3 of the excited state 5$^{2}P_{3/2}$ in the presence of coupling transitions F = 3 $\to$ F$^{\prime}$ = 2 and F = 3 $\to$ F$^{\prime}$ = 3, respectively. The effects of uncoupled magnetic sublevel transitions and coupling field's Rabi frequency on the EIT signal from these systems are studied using a simple theoretical model.Comment: 12 pages, 7 figure

Mutational Analysis in Pediatric Thyroid Cancer and Correlations with Age, Ethnicity, and Clinical Presentation.

BackgroundWell-differentiated thyroid cancer (WDTC) incidence in pediatrics is rising, most being papillary thyroid carcinoma (PTC). The objective of the study was to assess the prevalence of different mutations in pediatric WDTC and correlate the genotype with the clinical phenotype.MethodsThis is a single-center retrospective study. Thyroid tissue blocks from 42 consecutive pediatric WDTC patients who underwent thyroidectomy between 2001 and 2013 were analyzed at Quest Diagnostics for BRAF(V600E), RAS mutations (N,K,H), and RET/PTC and PAX8/PPARγ rearrangements, using validated molecular methods. Thyroid carcinomas included PTC, follicular thyroid carcinoma (FTC), and follicular variant of PTC (FVPTC).ResultsThirty-nine samples (29 females) were genotyped. The mean age at diagnosis was 14.7 years (range 7.9-18.4 years), and most were Hispanic (56.4%) or Caucasian (35.9%). The mean follow-up period was 2.9 years. Mutations were noted in 21/39 (53.8%), with both BRAF(V600E) (n = 9), and RET/PTC (n = 6) detected only in PTC. Mutations were detected in 2/5 FTC (PAX8/PPARγ and NRAS) and 3/6 FVPTC cases (PAX8/PPARγ). Of 28 PTC patients, 57.1% had mutations: 32.1% with BRAF(V600E), 21.4% with RET/PTC, and 3.6% with NRAS. Of patients with BRAF(V600E), 77.8% were Hispanic and 88.9% were >15 years, while all RET/PTC-positive patients were ≤15 years (p = 0.003). Tumor size, lymph node involvement, and distant metastasis at diagnosis (or soon after (131)I ablation) did not vary significantly based on the mutation.ConclusionsBRAF(V600E) was the most common mutation, especially in older and Hispanic adolescents. A larger, ethnically diverse pediatric cohort followed long term will enable the genotypic variability, clinical presentation, and response to therapy to be better assessed

High-energy quasi-monoenergetic neutron fields: existing facilities and future needs

The argument that well-characterised quasi-monoenergetic neutron (QMN) sources reaching into the energy domain >20 MeV are needed is presented. A brief overview of the existing facilities is given, and a list of key factors that an ideal QMN source for dosimetry and spectrometry should offer is presented. The authors conclude that all of the six QMN facilities currently in existence worldwide operate in sub-optimal conditions for dosimetry. The only currently available QMN facility in Europe capable of operating at energies >40 MeV, TSL in Uppsala, Sweden, is threatened with shutdown in the immediate future. One facility, NFS at GANIL, France, is currently under construction. NFS could deliver QMN beams up to about 30 MeV. It is, however, so far not clear if and when NFS will be able to offer QMN beams or operate with only so-called white neutron beams. It is likely that by 2016, QMN beams with energies >40 MeV will be available only in South Africa and Japan, with none in Europ

All-optical formation of a Bose-Einstein condensate for applications in scanning electron microscopy

We report on the production of a F=1 spinor condensate of 87Rb atoms in a single beam optical dipole trap formed by a focused CO2 laser. The condensate is produced 13mm below the tip of a scanning electron microscope employing standard all-optical techniques. The condensate fraction contains up to 100,000 atoms and we achieve a duty cycle of less than 10s.Comment: 5 pages, 4 figure

Optical Surface Scanning for Patient Positioning in Radiation Therapy: A Prospective Analysis of 1902 Fractions

Purpose/Objective: Reproducible patient positioning remains one of the major challenges in modern radiation therapy. Recently, optical surface scanners have been introduced into clinical practice in addition to well-established positioning systems, such as room laser and skin marks. The aim of this prospective study was to evaluate setup errors of the optical surface scanner Catalyst HD (C-RAD AB) in different anatomic regions. Material/Methods: Between October 2016 and June 2017 a total of 1902 treatment sessions in 110 patients were evaluated. The workflow of this study included conventional setup procedures using laser-based positioning with skin marks and an additional registration of the 3-dimensional (3D) deviations detected by the Catalyst system. The deviations of the surface-based method were then compared to the corrections of cone beam computed tomography alignment which was considered as gold standard. A practical Catalyst setup error was calculated between the translational deviations of the surface scanner and the laser positioning. Two one-sided t tests for equivalence were used for statistical analysis. Results: Data analysis revealed total deviations of 0.09 mm +/- 2.03 mm for the lateral axis, 0.07 mm +/- 3.21 mm for the longitudinal axis, and 0.44 mm +/- 3.08 mm vertical axis for the Catalyst system, compared to -0.06 +/- 3.54 mm lateral, 0.53 +/- 3.47 mm longitudinal, and 0.19 +/- 3.49 mm vertical for the laser positioning compared to cone beam computed tomography. The lowest positional deviations were found in the cranial region, and larger deviations occurred in the thoracic and abdominal sites. A statistical comparison using 2 one-sided t tests showed a general concordance of the 2 methods (P <= 0.036), excluding the vertical direction of the abdominal region (P=0.198). Conclusion: The optical surface scanner Catalyst HD is a reliable and feasible patient positioning system without any additional radiation exposure. From the head to the thoracic and abdominal region, a decrease in accuracy was observed within a comparable range for Catalyst and laser-assisted positioning