Analytical and experimental study of stratification and liquid-ullage coupling, 1 June 1964 - 31 May 1965

Closed-form solution for stratification of subcooled fluids in containers subjected to heating, and for liquid-ullage vapor couplin

The energetics and mass structure of regions of star formation: S201

Theoretical predictions about dust and gas in star forming regions are tested by observing a 4 arcmin region surrounding the radio continuum source in 5201. The object was mapped in two far infrared wavelengths and found to show significant extended emission. Under the assumption that the molecular gas is heated solely via thermal coupling with the dust, the volume density was mapped in 5201. The ratios of infrared optical depth to CO column density were calculated for a number of positions in the source. Near the center of the cloud the values are found to be in good agreement with other determinations for regions with lower column density. In addition, the observations suggest significant molecular destruction in the outer parts of the object. Current models of gas heating were used to calculate a strong limit for the radius of the far infrared emitting grains, equal to or less than 0.15 micron. Grains of about this size are required by the observation of high temperature (T equal to or greater than 20 K) gas in many sources

TWAM: A Certifying Abstract Machine for Logic Programs

Type-preserving (or typed) compilation uses typing derivations to certify correctness properties of compilation. We have designed and implemented a type-preserving compiler for a simply-typed dialect of Prolog we call T-Prolog. The crux of our approach is a new certifying abstract machine which we call the Typed Warren Abstract Machine (TWAM). The TWAM has a dependent type system strong enough to specify the semantics of a logic program in the logical framework LF. We present a soundness metatheorem which constitutes a partial correctness guarantee: well-typed programs implement the logic program specified by their type. This metatheorem justifies our design and implementation of a certifying compiler from T-Prolog to TWAM.Comment: 41 pages, under submission to ACM Transactions on Computational Logi

Mapping subglacial surfaces of temperate valley glaciers by two-pass migration of a radio-echo sounding survey

High-resolution maps of the glacier bed are developed through a pseudo-three-dimensional migration of a dense array of radio-echo sounding profiles. Resolution of three-dimensional maps of sub-glacial surfaces is determined by the radio-echo sounding wavelength, data spacing in the field, and migration. Based on synthetic radio-echo sounding profile experiments, the maximum resolution of the final map cannot exceed one half-wavelength. A methodology of field and processing techniques is outlined to develop a maximum-resolution map of the glacier bed. The field and processing techniques valley glacier in south-central Alaska. The field techniques and the processing steps used on the glacier result in a map of 20 m x 20 m resolution

Early and late results of surgery for Wolff-Parkinson-White syndrome

Surgical treatment for accessory atrioventricular connections was performed in 60 patients with Wolff-Parkinson-White syndrome between 1981 and 1986. The initial procedure successfully divided 69 of 73 pathways identified preoperatively, including 39 of 40 left free wall pathways, 23 of 24 posteroseptal pathways, six of seven right free wall pathways, and one of two anteroseptal pathways. Three additional pathways were identified for the first time during follow-up. The primary procedure was successful in curing 53 (88%) of the 60 patients and in dividing 69 (91%) of the total of 76 pathways. Subsequent procedures increased the overall clinical cure rate to 97%. The surgery was performed with low morbidity and no perioperative or late mortality. Patients were followed-up for a mean of 6.4 years (range four to nine years). No patient showed clinical or electrocardiographic evidence of recurrence of a pathway which had been divided surgically. We conclude that regardless of pathway site, surgical treatment carries a low risk and has a high probability of avoiding lifelong antiarrhythmic therapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75341/1/j.1445-5994.1991.tb04698.x.pd

Impact of the Manchester Glaucoma Enhanced Referral Scheme on NHS costs

Objectives: Glaucoma filtering schemes such as the Manchester Glaucoma Enhanced Referral Scheme (GERS) aim to reduce the number of false positive cases referred to Hospital Eye Services. Such schemes can also have wider system benefits, as they may reduce waiting times for other patients. However, previous studies of the cost consequences and wider system benefits of glaucoma filtering schemes are inconclusive. We investigate the cost consequences of the Manchester GERS. Design: Observational study. Methods: A cost analysis from the perspective of the National Health Service (NHS) was conducted using audit data from the Manchester GERS. Results: 2405 patients passed through the Manchester GERS from April 2013 to November 2016. 53.3% were not referred on to Manchester Royal Eye Hospital (MREH). Assuming an average of 2.3 outpatient visits to MREH were avoided for each filtered patient, the scheme saved the NHS approximately £2.76 per patient passing through the scheme. Conclusion: Our results indicate that glaucoma filtering schemes have the potential to reduce false positive referrals and costs to the NHS

In-line and cascaded DWDM transmission using a 15dB net-gain polarization-insensitive fiber optical parametric amplifier

We demonstrate and characterize polarization-division multiplexed (PDM) DWDM data transmission for the first time in a range of systems incorporating a net-gain polarization-insensitive fiber optical parametric amplifier (PI-FOPA) for loss compensation. The PI-FOPA comprises a modified diversity-loop architecture to achieve 15dB net-gain, and up to 2.3THz (~18nm) bandwidth. Three representative systems are characterized using a 100Gb/s PDM-QPSK signal in conjunction with emulated DWDM neighbouring channels: (a) a 4x75km in-line fiber transmission system incorporating multiple EDFAs and a single PI-FOPA (b) N cascaded PI-FOPA amplification stages in an unlevelled Nx25km recirculating loop arrangement, with no EDFAs used within the loop signal path, and (c) M cascaded PI-FOPA amplification stages as part of an Mx75.6km gain-flattened recirculating loop system with the FOPA compensating for the transmission fiber loss, and EDFA compensation for loop switching and levelling loss. For the 4x75km in-line system (a), we transmit 45x50GHz-spaced signals (‘equivalent’ data-rate of 4.5Tb/s) with average OSNR penalty of 1.3dB over the band at 10−3 BER. For the unlevelled ‘FOPA-only’ 25.2km cascaded system (b), we report a maximum of eight recirculations for all 10x100GHz-spaced signals, and five recirculations for 20x50GHz-spaced signals. For the 75.6km levelled system (c), we achieve eight recirculations for all 20x50GHz signals resulting in a total transmission distance of 604.8km

NGC 2024: Far-infrared and radio molecular observations

Far infrared continuum and millimeter wave molecular observations are presented for the infrared and radio source NGC 2024. The measurements are obtained at relatively high angular resolution, enabling a description of the source energetics and mass distribution in greater detail than previously reported. The object appears to be dominated by a dense ridge of material, extended in the north/south direction and centered on the dark lane that is seen in visual photographs. Maps of the source using the high density molecules CS and HCN confirm this picture and allow a description of the core structure and molecular abundances. The radio molecular and infrared observations support the idea that an important exciting star in NGC 2024 has yet to be identified and is centered on the dense ridge about 1' south of the bright mid infrared source IRS 2. The data presented here allows a presentation of a model for the source