Drag coefficients for spheres for free molecular flow in nitrogen at satellites' velocities

Momentum transfer by nitrogen molecular beam to surfaces measured as function of angle of incidenc

Design study of magnetic eddy-current vibration suppression dampers for application to cryogenic turbomachinery

Cryogenic turbomachinery used to pump high pressure fuel (liquid H2) and oxidizer (liquid O2) to the main engines of the Space Shuttle have experienced rotor instabilities. Subsynchronous whirl, an extremely destructive instability, has caused bearing failures and severe rubs in the seals. These failures have resulted in premature engine shutdowns or, in many instances, have limited the power level to which the turbopumps could be operated. The feasibility of using an eddy current type of damping mechanism for the Space Shuttle Main Engine is outlined

An experimental investigation of an axisymmetric jet in a coflowing airstream

The flow development of an axisymmetric jet exhausting into a moving airstream has been studied. The jet has a Reynolds number of 22,600, and the ratio of the jet velocity to the wind tunnel velocity is 5.1 to 1. The flow field of the axisymmetric jet was examined at locations varying from approximately zero to eight diameters downstream of the orifice. Of primary concern at each downstream location was the mapping of the one point statistical properties of the flow, including mean velocity, turbulent intensity, and intermittency. Autocorrelations and power spectral density curves were determined for both the fluctuating velocity field and the concentration signal at various distances from the jet's center line for different downstream locations. A laser Doppler velocimeter, using a phase locked loop processor, was used to make the desired velocity field measurements which were compared with hot wire anemometer and pressure probe data

The interaction of oxygen atoms with solid surfaces at eV energies Annual status report, 1 Jun. 1968 - 31 May 1969

Interaction of oxygen atoms with solid surfaces at eV energie

The importance of acknowledgement of emotions in routine patient psychological assessment:The example of the dental setting

This work was funded by the Chief Scientist Office, Scotland under their Clinical Academic Fellowship Scheme (grant number: CAF/07/02).Objective:  To investigate, by means of a conceptual model, the effect of dental staff engaging with their patients who share their level of dental anxiety in a short screening questionnaire. Methods :  Three consecutive studies based in the UK primary dental care services were conducted. Each study adopted a randomised group design to focus on the possible influence on patient state anxiety of the dentist becoming aware of their patients' dental anxiety from the self-reports of the Modified Dental Anxiety Scale (MDAS). Results :  A consistent finding in the first two studies was that the presentation of MDAS score sheet to the dentist was effective in reducing patient state anxiety when leaving the surgery. The third study provided supportive evidence that a more permanent anxiolytic effect of the presentation of the MDAS to the dentist was associated with the dentist responding openly to their patient about the fears expressed. Conclusion:  The active engagement of dental staff in the formal presentation of dental anxiety screening confers a reliable benefit to dentally anxious patients. Clinical implications:   Anxiety assessments in clinical service may give patients significant relief when staff acknowledge and engage patients when presented with their self-reported ratings.PostprintPeer reviewe

Cemented mounds and hydrothermal sediments on the detachment surface at Kane Megamullion : a new manifestation of hydrothermal venting

Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 14 (2013): 3352–3378, doi:10.1002/ggge.20186.Long-lived detachment faults are now known to be important in tectonic evolution of slow-spreading mid-ocean ridges, and there is increasing evidence that fluid flow plays a critical role in development of detachment systems. Here we document a new manifestation of low-temperature hydrothermal venting associated with the detachment fault that formed Kane Megamullion ∼3.3–2.1 m.y. ago in the western rift-valley wall of the Mid-Atlantic Ridge. Hydrothermal effects on the detachment surface include (1) cemented mounds of igneous rock and chalk debris containing hydrothermal Mn oxides and Fe oxyhydroxides, and (2) layered deposits of similar Fe-Mn minerals ± interbedded chalks. Mounds are roughly conical, ∼1–10 m high, and contain primarily basalts with lesser gabbro, serpentinite, and polymict breccia. The layered Fe-Mn-rich sediments are flat-bedded to contorted and locally are buckled into low-relief linear or polygonal ridges. We propose that the mounds formed where hydrothermal fluids discharged through the detachment hanging wall near the active fault trace. Hydrothermal precipitates cemented hanging-wall debris and welded it to the footwall, and this debris persisted as mounds as the footwall was exhumed and surrounding unconsolidated material sloughed off the sloping detachment surface. Some of the layered Fe-Mn-rich deposits may have precipitated from fluids discharging from the hanging-wall vents, but they also precipitated from low-temperature fluids venting from the exposed footwall through overlying chalks. Observed natural disturbance and abnormally thin hydrogenous Fe-Mn crusts on some contorted, hydrothermal Fe-Mn-rich chalks on ∼2.7 Ma crust suggest diffuse venting that is geologically recent. Results of this study imply that there are significant fluid pathways through all parts of detachment systems and that low-temperature venting through fractured detachment footwalls may continue for several million years off-axis.NSF grant 0118445 supported data acquisition and processing for Knorr Cruise 180- 2. The Deep Ocean Exploration Institute at Woods Hole Oceanographic Institution supported research and analytical costs for this study.2014-03-0

The technology and craft organisation of Kushite technical ceramic production at Meroe and Hamadab, Sudan

This paper seeks to contribute to the growing knowledge of iron production in ancient Sudan by examining the technology and craft organisation involved in the production of technical ceramics, which were integral to the iron smelting process. The focus of this study are the technical ceramics including tuyères, furnace linings, and furnace bricks, recovered from various slag heaps located at the archaeological sites of the Royal City of Meroe and the Meroitic town site of Hamadab. We used macroscopic examination and thin-section petrography to identify the source of raw materials and methods used in preparing the raw materials, to characterise the level of craft specialisation, and to infer the broader socio-political developments that might have influenced how the production of technical ceramics was organised. The resulting data reveal that changes occurred within the production of technical ceramics throughout different periods of Kushite history (traditionally divided into Napatan and Meroitic) and during the post-Meroitic period, and we argue that the observed changes might have been related to the rise and fall of the Kingdom of Kush. The production of technical ceramics was marked by clear distinction in raw materials and paste preparation methods used for different types of technical ceramics, and a high degree of compositional and technological homogeneity within each type of technical ceramic during the Napatan and earlier Meroitic periods, coinciding with the time when Kush rose to and was at the height of its power. The production of technical ceramics appears to have exhibited more diversity in terms of the raw materials and paste preparation methods and lower degree of homogeneity during the later and post-Meroitic periods when the economic and political influence and power of the Kingdom of Kush is described as declining and ultimately ceasing to exist. Perhaps the most drastic change in the production of technical ceramics took place in the post-Meroitic period, which was characterised by lower level of specialisation, as well as the possibility of using a different technological approach to iron smelting.Qatar Sudan Archaeology Project grant 037 UCL Qatar core fundin

Unsteady loads due to propulsive lift configurations. Part B: Pressure and velocity measurements in a three dimensional wall jet

The effects of increasing the velocity ratio, lambda sub j were explored. The quantities measured include the width of the mixing region, the mean velocity field, turbulent intensities and time scales. In addition, wall and static pressure velocity correlations and coherences are presented. The velocity measurements were made using a laser Doppler velocimeter with a phase locked loop processor. The fluctuating pressures were monitored using condenser type microphones

Neuropsychological functioning and chronic methadone use:a systematic review and meta-analysis

The authors would like to thank the NHS Fife Research and Development Department for supporting this project.Introduction: There is a presumption that neurocognition is commonly impaired in chronicmethadone exposed individuals (CM) when compared with healthy controls (HP).Additionally, it remains unclear if short term (< 1 year) abstinence (AP) is associated with an altered cognitive profile when compared with CM. Method: A random effect model approach was used on data assembled into the Comprehensive Meta-Analysis programme.Cohen’s d effect sizes and a significance levels of p<0.01 were calculated for each domain. Results: Data from a total cohort of 1063 CM, 412 AP and 879 HP participants, from 23 independent studies indicate global impairments in neurocognitive function in CM relative to HP participants. The smaller body of evidence comparing CM to AP participants is inconclusive. Conclusion: Methodological issues such as small sample sizes, heterogeneity and poor quality limited the interpretation of the results and does not address whether the observed impairments reflect co-morbid functioning, methadone-related sedation and/or other factors. Only higher quality longitudinal studies will permit confident interpretation of the results observed in this meta-analysis.PostprintPeer reviewe