Requirements for regional short-haul air service and the definition of a flight program to determine neighborhood reactions to small transport aircraft

An evaluation of the current status and future requirements of an intraregional short haul air service is given. A brief definition of the different types of short haul air service is given. This is followed by a historical review of previous attempts to develop short haul air service in high density urban areas and an assessment of the current status. The requirements for intraregional air service, the need for economic and environmental viability and the need for a flight research program are defined. A detailed outline of a research program that would determine urban community reaction to frequent operations of small transport aircraft is also given. Both the operation of such an experiment in a specific region (San Francisco Bay area) and the necessary design modifications of an existing fixed wing aircraft which could be used in the experiment are established. An estimate is made of overall program costs

Improving South African medical curricula related to traditional health systems

Background. Increased co-ordination and co-operation between traditional and biomedical health systems in South Africa (SA) is a national priority. To improve care, practitioners in both systems must learn to recognise the value of their parallel counterparts, and such lessons should begin in medical school. However, there is little research regarding the way in which SA’s medical students are taught to interact with the traditional medicine (TM) system. Objectives. To explore how SA medical students perceive their curriculum as it relates to the traditional health system and to describe their suggestions for improvement. Methods. We conducted individual in-depth interviews and focus group discussions with 43 final-year medical students across 3 SA medical schools. We applied thematic analysis to improve our understanding of student-reported experiences with TM in their medical school curricula. Results. All 3 medical schools rely heavily on hidden curricula to educate students on the SA traditional health system. These hidden curricula are largely negative and learnt primarily from witnessing faculty-client interactions involving TM use. Students across the institutions agree that this problematic deficit in formal teaching contributes to their incompetence in treating patients who use TM. Their suggestions for improvement focused largely around 3 themes: (i) understanding the fundamentals of the traditional health system; (ii) empathising with patient use of TM; and (iii) promoting broader structural integration of the two health systems. Conclusion. Medical students in SA recognise the value of increased exposure to and education surrounding the traditional health system. Future curricular interventions should focus on increasing formal teaching of TM, directly addressing the hidden curriculum related to the topic, and instituting policies and initiatives that improve integration of the SA biomedical and traditional healing paradigms on a structural level

Onset of dissipation in ballistic atomic wires

Electronic transport at finite voltages in free-standing gold atomic chains of up to 7 atoms in length is studied at low temperatures using a scanning tunneling microscope (STM). The conductance vs voltage curves show that transport in these single-mode ballistic atomic wires is non-dissipative up to a finite voltage threshold of the order of several mV. The onset of dissipation and resistance within the wire corresponds to the excitation of the atomic vibrations by the electrons traversing the wire and is very sensitive to strain.Comment: Revtex4, 4 pages, 3 fig

Verification of a many-ion simulator of the Dicke model through slow quenches across a phase transition

We use a self-assembled two-dimensional Coulomb crystal of $\sim 70$ ions in the presence of an external transverse field to engineer a simulator of the Dicke Hamiltonian, an iconic model in quantum optics which features a quantum phase transition between a superradiant/ferromagnetic and a normal/paramagnetic phase. We experimentally implement slow quenches across the quantum critical point and benchmark the dynamics and the performance of the simulator through extensive theory-experiment comparisons which show excellent agreement. The implementation of the Dicke model in fully controllable trapped ion arrays can open a path for the generation of highly entangled states useful for enhanced metrology and the observation of scrambling and quantum chaos in a many-body system.Comment: 6 + 5 pages, 2 + 5 figures. arXiv admin note: substantial text overlap with arXiv:1711.0739

Dynamics of axialized laser-cooled ions in a Penning trap

We report the experimental characterization of axialization - a method of reducing the magnetron motion of a small number of ions stored in a Penning trap. This is an important step in the investigation of the suitability of Penning traps for quantum information processing. The magnetron motion was coupled to the laser-cooled modified cyclotron motion by the application of a near-resonant oscillating quadrupole potential (the "axialization drive"). Measurement of cooling rates of the radial motions of the ions showed an order-of-magnitude increase in the damping rate of the magnetron motion with the axialization drive applied. The experimental results are in good qualitative agreement with a recent theoretical study. In particular, a classical avoided crossing was observed in the motional frequencies as the axialization drive frequency was swept through the optimum value, proving that axialization is indeed a resonant effect.Comment: 8 pages, 9 figure

Fluxes of soot black carbon to South Atlantic sediments

Deep sea sediment samples from the South Atlantic Ocean were analyzed for soot black carbon (BC), total organic carbon (TOC), stable carbon isotope ratios (delta C-13), and polycyclic aromatic hydrocarbons (PAHs). Soot BC was present at low concentrations (0.04-0.17% dry weight), but accounted for 3-35% of TOC. Fluxes of soot BC were calculated on the basis of known sedimentation rates and ranged from 0.5 to 7.8 mu g cm(-2) a(-1), with higher fluxes near Africa compared to South America. Values of delta C-13 indicated a marine origin for the organic carbon but terrestrial sources for the soot BC. PAH ratios implied a pyrogenic origin for most samples and possibly a predominance of traffic emissions over wood burning off the African coast. A coupled ocean-atmosphere-aerosol-climate model was used to determine fluxes of BC from 1860 to 2000 to the South Atlantic. Model simulation and measurements both yielded higher soot BC fluxes off the African coast and lower fluxes off the South American coast; however, measured sedimentary soot BC fluxes exceeded simulated values by similar to 1 mu g cm(-2) a(-1) on average (within a factor of 2-4). For the sediments off the African coast, soot BC delivery from the Congo River could possibly explain the higher flux rates, but no elevated soot BC fluxes were detected in the Amazon River basin. In total, fluxes of soot BC to the South Atlantic were similar to 480-700 Gg a(-1) in deep sea sediments. Our results suggest that attempts to construct a global mass balance of BC should include estimates of the atmospheric deposition of BC

Physiological Reflux and Venous Diameter Change in the Proximal Lower Limb Veins During a Standardised Valsalva Manoeuvre

AbstractObjectives: the aim of this study was to provide normal values for venous diameter at rest, and venous diameter and physiologic venous reflux during a standardised Valsalva manoeuvre. The impact of the patient's sex, body mass index (BMI), and family history was investigated. Material and methods: eighty legs of 40 healthy volunteers were investigated in a supine position. The median age was 28 years (range 20–66 years). The common femoral vein (CFV), the proximal superficial femoral vein (SFV) and the proximal long saphenous vein (LSV) were investigated by duplex sonography. The following parameters were assessed: resting diameter (VDrest) and maximum diameter (VDmax) as well as reflux time (tr) during the Valsalva manoeuvre. The Valsalva manoeuvre was elicited by a forceful expiration into a tube system. The standard values used were a pressure of 30 mmHg, established within 0.5 seconds (s) and maintained over a time period of at least 3 s. Results: mean VDrestand VDmaxwere 8.3±2.2 and 11.1±2.8 mm in the CFV, 5.9±1.3 and 7.2±1.6 mm in the SFV and 3.5±0.9 and 4.3±1.4 mm in the LSV. Mean values for trwere 0.61±0.63 s in the CFV, 0.25±0.26 s in the SFV and 0.28±0.40 s in the LSV. A BMI >22.5 kg/m2was associated with statistically significant larger values for VDrestand tr. If adjusted for BMI, trin the SFV and the LSV did not differ by sex. For healthy subjects with first-degree relatives suffering from varicose veins (n=19), mean VDrestin the SFV as well as VD in the LSV was significantly larger (p=0.02, 0.05, respectively). Coefficients of variation for repeated measurements (VDrest, VDmax, tr) in the same segment varied between 3.3% and 16.4% for the three investigated sites.Conclusions: normal values for VDrestand VDmaxas well as reflux time during a standardised Valsalva manouevre were assessed in the proximal lower limb veins. The influences of BMI, sex and family history were investigated. The described standardised Valsalva manoeuvre led to highly reproducible results and can be recommended for further research projects or as a routine procedure for the assessment of venous reflux