Design and characterization of all-cryogenic low phase-noise sapphire K-band oscillator for sattelite communication

An all-cryogenic oscillator consisting of a frequency-tunable sapphire resonator, a high-temperature superconducting filter and a pseudomorphic high electron-mobility transistor amplifier was designed for the K-band frequency range and investigated. Due to the high quality factor of the resonator above 1000 000 and the low amplifier phase noise of approximately -133 dBc/Hz at a frequency offset of 1kHz from the carrier, we have achieved oscillator phase-noise values superior to quartz-stabilized oscillators at the same carrier frequency for offset frequencies higher than 100 Hz. In addition to, low phase noise, our prototype oscillator possesses mechanical and electrical frequency tunability. We have implemented a two-step electrical tuning arrangement consisting of a varactor phase shifter integrated within the amplifier circuit (fine tuning by 5'kHz) and a dielectric plunger moved by a piezomechanical transducer inside the resonator housing (course tuning by 50 kHz). This tuning range is sufficient for phase locking and for electronic compensation of temperature drifts occurring during operation of the device employing a miniaturized closed-cycle Stirling-type cryocooler

Deterministic cavity quantum electrodynamics with trapped ions

We have employed radio-frequency trapping to localize a single 40Ca+-ion in a high-finesse optical cavity. By means of laser Doppler cooling, the position spread of the ion's wavefunction along the cavity axis was reduced to 42 nm, a fraction of the resonance wavelength of ionized calcium (λ = 397 nm). By controlling the position of the ion in the optical field, continuous and completely deterministic coupling of ion and field was realized. The precise three-dimensional location of the ion in the cavity was measured by observing the fluorescent light emitted upon excitation in the cavity field. The single-ion system is ideally suited to implement cavity quantum electrodynamics under cw conditions. To this end we operate the cavity on the D3/2–P1/2 transition of 40Ca+ (λ = 866 nm). Applications include the controlled generation of single-photon pulses with high efficiency and two-ion quantum gates

First record of Bengal reticulated puffer Chelonodontops bengalensis (Tetraodontiformes: Tetraodontidae) from Odisha coast, north-western Bay of Bengal with taxonomic notes

The present study reports the first record of Bengal reticulated puffer, Chelonodontops bengalensis from Odisha coast in the north-western Bay of Bengal based on two specimens (226 – 301 mm SL), each collected from Paradeep and Bahabalpur in 2018 and 2019, respectively. The detailed morphological features of C. bengalensis are provided and compared with its previous records. The species is distinguished from its congeners by having 12 dorsal fin rays, 10 anal fin rays, 18 – 19 pectoral fin rays, 10 – 11 caudal fin rays, nasal organ cup shaped with unequal sized flaps, and dorsal profile of body covered with white spots of various shape and size and ventral side silvery white. Our study indicated the range extension of C. bengalensis from its known geographical range i.e. Bangladesh and West Bengal towards south in the northern Bay of Bengal

Morgagni hernia repair in children over two decades: Institutional experience, systematic review, and meta-analysis of 296 patients

BACKGROUND/PURPOSE: Morgagni diaphragmatic hernia (MH) is rare. We report our experience based on routine patch use in MH repair to curb recurrence. A systematic review and meta-analysis were performed to study the recurrence and complications associated with minimally invasive surgery and the use of patch. METHODS: We retrospectively reviewed all cases of MH who underwent first-time repair in 2012-2017 in our institution to determine recurrence and complication rate. A MEDLINE search related to minimally invasive surgery (MIS) and patch repair of MH was conducted for systematic review. Eligible articles published from 1997-2017 with follow-up data available were included. Primary outcomes measured were recurrence and complication. Meta-analysis to compare open versus MIS and primary versus patch repair in the MIS group were performed in comparative cohorts. Continuous data were presented as median (range), and statistical significance was P<0.05. RESULTS: In our institution, 12 consecutive patients aged 17-month-old (22 days-7 years), underwent laparoscopic patch repair of MH, with one conversion to laparotomy. No recurrence or significant complication occurred over a follow-up period of 8 months (1-48 months). Thirty-six articles were included from literature review and were combined with the current series. All were retrospective case reports or series, of which 6 were comparative cohorts with both MIS and open repairs. A total of 296 patients from 37 series were ultimately used for analysis: 80 had open repair (4 patch) and 216 had MIS repair (32 patch), with a patch rate of 12%. There were 13 recurrences (4%): no difference between open and MIS repairs (4/80 vs 9/216, p=0.75); recurrence rate following primary repair was 13/260 (5%), but no recurrence occurred with 36 patch repairs. Meta-analysis showed no difference in recurrence between open and MIS repair (p=0.83), whereas patch repair was associated with 14% less recurrence compared with primary repair, although it did not reach statistical significance (p=0.12). There were 13 complications (5%): no difference between open and MIS repairs (5/80 vs 8/216, p=0.35). One small bowel obstruction occurred in a patient who had laparoscopic patch repair. CONCLUSION: In MH, recurrence and complication rates are comparable between MIS and open repairs. Use of patch appeared to confer additional benefit in reducing recurrence. TYPE OF STUDY: Systematic review LEVEL OF EVIDENCE: 3A

Site amplification in the Kathmandu Valley during the 2015 M7.6 Gorkha, Nepal earthquake

The 25th April 2015 M7.6 Gorkha earthquake caused significant damage to buildings and infrastructure in both Kathmandu and surrounding areas as well as triggering numerous, large landslides. This resulted in the loss of approximately 8600 lives. In order to learn how the impact of such events can be reduced on communities both in Nepal and elsewhere, the Earthquake Engineering Field Investigation Team (EEFIT) reconnaissance mission was undertaken, aiming to look at damage patterns within the country. Passive, microtremor recordings in severely damaged areas of the Kathmandu Valley, as well as at the main seismic recording station in Kathmandu (USGS station KATNP) are used to determined preliminary shear wave velocity (Vs) profiles for each site. These profiles are converted into spectral acceleration using the input motion of the Gorkha earthquake. The results are limited, but show clear site amplification within the Siddhitol Region. The resulting ground motions exceed the design levels from the Nepalese Building Codes, indicating the need for site-specific hazard analysis and for revision of the building code to address the effect of site amplificatio

The Sasa-Satsuma higher order nonlinear Schrodinger equation and its bilinearization and multi-soliton solutions

Higher order and multicomponent generalizations of the nonlinear Schrodinger equation are important in various applications, e.g., in optics. One of these equations, the integrable Sasa-Satsuma equation, has particularly interesting soliton solutions. Unfortunately the construction of multi-soliton solutions to this equation presents difficulties due to its complicated bilinearization. We discuss briefly some previous attempts and then give the correct bilinearization based on the interpretation of the Sasa-Satsuma equation as a reduction of the three-component Kadomtsev-Petvishvili hierarchy. In the process we also get bilinearizations and multi-soliton formulae for a two component generalization of the Sasa-Satsuma equation (the Yajima-Oikawa-Tasgal-Potasek model), and for a (2+1)-dimensional generalization.Comment: 13 pages in RevTex, added reference

Saving behaviour and health: A high-dimensional Bayesian analysis of British panel data

We develop a two-part high-dimensional Bayesian modelling approach to analyse the relationship between saving behaviour and health. In contrast to the existing literature, our approach allows different data-generating processes for the decision to save and the amount saved, and therefore unveils a more detailed picture of the relationship between financial behaviour and health than previous work. We explore different measures of saving, including monthly saving behaviour and the stock of financial assets held. Further, we exploit British panel data, which includes an extensive range of biomarkers. Our second contribution lies in comparing the effects of these objective measures of health with commonly used self-assessed health measures. We find that health is a significant determinant of saving behaviour and financial asset holding, and that biomarker measures have differential impacts on saving behaviour compared to self-reported health measures

Collective oscillations of a 1D trapped Bose gas

Starting from the hydrodynamic equations of superfluids, we calculate the frequencies of the collective oscillations of a harmonically trapped Bose gas for various 1D configurations. These include the mean field regime described by Gross-Pitaevskii theory and the beyond mean field regime at small densities described by Lieb-Liniger theory. The relevant combinations of the physical parameters governing the transition between the different regimes are discussed.Comment: 4 pages, 2 figure

Very high energy gamma-ray emission from X-ray transients during major outbursts

Context: Some high mass X-ray binaries (HMXB) have been recently confirmed as gamma-ray sources by ground based Cherenkov telescopes. In this work, we discuss the gamma-ray emission from X-ray transient sources formed by a Be star and a highly magnetized neutron star. This kind of systems can produce variable hadronic gamma-ray emission through the mechanism proposed by Cheng and Ruderman, where a proton beam accelerated in the pulsar magnetosphere impacts the transient accretion disk. We choose as case of study the best known system of this class: A0535+26. Aims: We aim at making quantitative predictions about the very high-energy radiation generated in Be-X ray binary systems with strongly magnetized neutron stars. Methods: We study the gamma-ray emission generated during a major X-ray outburst of a HMXB adopting for the model the parameters of A0535+26. The emerging photon signal from the disk is determined by the grammage of the disk that modulates the optical depth. The electromagnetic cascades initiated by photons absorbed in the disk are explored, making use of the so-called "Approximation A" to solve the cascade equations. Very high energy photons induce Inverse Compton cascades in the photon field of the massive star. We implemented Monte Carlo simulations of these cascades, in order to estimate the characteristics of the resulting spectrum. Results: TeV emission should be detectable by Cherenkov telescopes during a major X-ray outburst of a binary formed by a Be star and a highly magnetized neutron star. The gamma-ray light curve is found to evolve in anti-correlation with the X-ray signal.Comment: 8 pages, 7 figures, accepted for publication in Astronomy and Astrophysical journa