12,536 research outputs found
Ultrahigh vacuum measuring ionization gauge
The ionization gage described consists of separate ionization and collector regions connected at an exit area with a modulator electrode. In addition to the standard modulation function, the modulator in this location yields a suprising increase in collector current, apparently due to improved focussing and extraction of ions from the ionization region
Gauge calibration by diffusion
Vacuum gage calibration by diffusing a known quantity of gas through a heated barrier into a gauge is examined. The gas flow raises the pressure in the gauge to known level and is then compared with the gauge's pressure reading
Study of density calibration in space Final report, 18 Jun. 1964 - 18 Aug. 1965
Design, construction, and experimental evaluation of in-flight calibration system for satellite mass spectrometers and pressure gauge
Development of an accurate wide range ultra high vacuum gauge calibration method
Accurate wide range ultrahigh vacuum gauge calibration method using pressure attenuation, atomic beam, and cryopumping techniques to evaluate system components and performanc
Development of an accurate wide range ultra high vacuum gauge calibration method, 29 June 1966 - 28 February 1968
Calibration method and ultrahigh vacuum components for ionization gage and mass spectromete
Plume flowfield analysis of the shuttle primary Reaction Control System (RCS) rocket engine
A solution was generated for the physical properties of the Shuttle RCS 4000 N (900 lb) rocket engine exhaust plume flowfield. The modeled exhaust gas consists of the five most abundant molecular species, H2, N2, H2O, CO, and CO2. The solution is for a bare RCS engine firing into a vacuum; the only additional hardware surface in the flowfield is a cylinder (=engine mount) which coincides with the nozzle lip outer corner at X = 0, extends to the flowfield outer boundary at X = -137 m and is coaxial with the negative symmetry axis. Continuum gas dynamic methods and the Direct Simulation Monte Carlo (DSMC) method were combined in an iterative procedure to produce a selfconsistent solution. Continuum methods were used in the RCS nozzle and in the plume as far as the P = 0.03 breakdown contour; the DSMC method was used downstream of this continuum flow boundary. The DSMC flowfield extends beyond 100 m from the nozzle exit and thus the solution includes the farfield flow properties, but substantial information is developed on lip flow dynamics and thus results are also presented for the flow properties in the vicinity of the nozzle lip
Development of a gas sampling system
Theoretical analysis and computed performance evaluation of high speed entry vehicle gas sampling syste
Extension of gage calibration study in extreme high vacuum /orbitron and magnetron studies/
Orbitron and magnetron studies for gauge calibration in extreme high vacuu
Glioblastoma in the elderly - how do we choose who to treat?
Objective:
Glioblastoma (GBM) is the commonest primary malignant brain tumour amongst the adult population. Incidence peaks in the 7th and 8th decades of life and as our global population ages, rates are increasing. GBM is an almost universally fatal disease with life expectancy in the range of 3–5 months amongst the elderly.
Materials and Methods:
The assessment of elderly GBM patients prior to treatment decisions is poorly researched and unstandardised. In order to begin tackling this issue we performed a cross-sectional survey across all UK based consultant neuro-oncologists to review their current practice in assessing elderly GBM patients.
Results:
There were 56 respondents from a total of 93 recipients (60% response rate). All respondents confirmed that at least some patients aged 70 or over were referred to their clinics from the local multidisciplinary team meeting (MDT). Only 18% of consultants routinely performed a cognitive or frailty screening test at initial consultation. Of those who performed a screening test, the majority reported that the results of the test changed their treatment decision in approximately 50% of cases. Participants ranked performance status as the most important factor in determining treatment decisions.
Conclusions:
Considering the heterogeneity of this patient population, we argue that performance status is a crude measure of vulnerability within this cohort. Elderly GBM patients represent a unique clinical scenario because of the complexity of distinguishing neuro-oncology related symptoms from general frailty. There is a need for specific geriatric assessment models tailored to the elderly neuro-oncology population in order to facilitate treatment decisions
Laser modulation at the atomic level monthly report no. 8, 1 - 28 feb. 1965
Measurement of temperature dependence of energy levels involved in laser emissio
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