Preliminary feasibility study of a multi-Phobos encounter experiment during the Viking extended mission

The Viking '75 Mission to Mars is reported which permits a truly unique opportunity to explore the natural satellite, Phobos, from distances measured in tens of kilometers. A preliminary feasibility study has been made which shows that a science mission involving a Phobos close encounter is technically feasible and within the capabilities of the current Viking design. For less than 20 m/s, the Viking Orbiter can provide approximately two 40-day periods of close observation of Phobos, with the first encounter period in January and the second in March, 1977. Multi-pass images of the entire satellite from nearly all aspect angles and with resolution on the order of 10 meters are possible. Close encounters will permit mass determinations to an accuracy of tens of percent. These experiments can be performed in series with the nominal mission; thus, providing complementary scientific information without compromising the original mission and science objectives

Shear-driven size segregation of granular materials: modeling and experiment

Granular materials segregate by size under shear, and the ability to quantitatively predict the time required to achieve complete segregation is a key test of our understanding of the segregation process. In this paper, we apply the Gray-Thornton model of segregation (developed for linear shear profiles) to a granular flow with an exponential profile, and evaluate its ability to describe the observed segregation dynamics. Our experiment is conducted in an annular Couette cell with a moving lower boundary. The granular material is initially prepared in an unstable configuration with a layer of small particles above a layer of large particles. Under shear, the sample mixes and then re-segregates so that the large particles are located in the top half of the system in the final state. During this segregation process, we measure the velocity profile and use the resulting exponential fit as input parameters to the model. To make a direct comparison between the continuum model and the observed segregation dynamics, we locally map the measured height of the experimental sample (which indicates the degree of segregation) to the local packing density. We observe that the model successfully captures the presence of a fast mixing process and relatively slower re-segregation process, but the model predicts a finite re-segregation time, while in the experiment re-segregation occurs only exponentially in time

Phase transition in the modified fiber bundle model

We extend the standard fiber bundle model (FBM) with the local load sharing in such a way that the conservation of the total load is relaxed when an isolated fiber is broken. In this modified FBM in one dimension (1D), it is revealed that the model exhibits a well-defined phase transition at a finite nonzero value of the load, which is in contrast to the standard 1D FBM. The modified FBM defined in the Watts-Strogatz network is also investigated, and found is the existences of two distinct transitions: one discontinuous and the other continuous. The effects of the long-range shortcuts are also discussed.Comment: 7 pages, to appear in Europhys. Let

Localized transverse bursts in inclined layer convection

We investigate a novel bursting state in inclined layer thermal convection in which convection rolls exhibit intermittent, localized, transverse bursts. With increasing temperature difference, the bursts increase in duration and number while exhibiting a characteristic wavenumber, magnitude, and size. We propose a mechanism which describes the duration of the observed bursting intervals and compare our results to bursting processes in other systems.Comment: 4 pages, 8 figure

UK National Audit of Early Syphilis Management. Case notes audit: diagnosis and treatment

A national audit of 781 early syphilis cases presenting during 2002–03 in UK genitourinary medicine clinics was conducted in late 2004, organized through the Regional Audit Groups. Data were aggregated by region and National Health Service trust, allowing practice to be compared between regions, between trusts within regions, as well as to national averages and the UK National Guidelines. An enzyme immunoassay was used to diagnose 695 (89%) cases (regional range 18–100%). Use of a non-treponemal test was not recorded for 44 (6%) cases. Dark ground microscopy was used in the diagnosis of only 80 (29%) primary cases. Uptake of HIV testing was 77% (range 69–94%). Nationally, 527 (67%) treatments were parenteral, with almost equal use of benzathine penicillin G for 262 (50%, range 0–97%) cases and procaine penicillin G (PPG) for 260 cases (49%, range 3–100%). There were 14 (5%) treatments with less than the recommended 750 mg dose of PPG. One hundred and five (40%) PPG treatments were with greater than 750 mg and/or for longer than 10 days of which 76 (72%) were for early latent syphilis and/or cases with HIV infection. One hundred and ninety two (86%, range 0–100%) of all oral treatments were with doxycycline. The recommended regimen of 100 mg doxycycline twice daily for 14 days was used for 104 (53%) cases; the other 91 (47%) treatments were with a variety of regimens, mainly treatments with larger doses and/or longer treatment intervals and some combination treatments. Fourteen (2%) cases were not treated; treatment was not reported for seven (0.9%) and not known for 10 (1.3%) cases, who were treated at other centres

UK National Audit of Early Syphilis Management. Clinics audit: screening for and management of early syphilis

Data were provided by 131 clinics, and 56% of cases were managed in clinics in the London regions in 2003. Three clinics (2%) do not routinely screen new patients for syphilis, and 28 clinics (21%) do not routinely screen ‘rebook’ patients who have had a new partner. More than 80% of clinics routinely conduct cardiovascular and neurological examinations, although chest radiography is only performed by 50% of clinics and lumbar puncture by 13%. Only 19 (14%) clinics indicated not routinely using the recommended procaine penicillin G (PPG) regimen or one- or two-dose benzathine penicillin G (BPG) regimens for early syphilis, with 57% providing two doses of BPG 2.4 g, 40% providing PPG 750 mg for 10 days, and 15% providing one dose of BPG 2.4 g. Only seven clinics (5%) indicated that they provided treatment for early syphilis with PPG that is inferior to that recommended in the national guidelines. Only 18 clinics specified using the recommended dose and duration (or in excess of this) of PPG for neurosyphilis for cases with HIV infection. Provision for management of severe penicillin reaction is good, although few patients are desensitized. All clinics report that contact tracing for early syphilis is provided, and is mainly the responsibility of health advisers. Compared with auditing outcomes, audit of management policies overestimated performance in contact tracing and provision of dark ground microscopy

UK National Audit of Early Syphilis Management. Case-notes audit: contact tracing, information giving, follow-up and outcomes

Contact tracing was provided for 683/781 (87%, regional range 57–97%) cases, and identified 997 traceable contacts of whom 511 (51%) were seen, short of the recommended standard of 60%. However, the performance range for this standard was 26–70%, with seven regions achieving 60% or more. Of 511, 215 (42%, range 3–73%) contacts had syphilis. Treatment completion was recorded for 691 (88%, range 71–100%) cases, and resolution of lesions for 348/469 (74%, range 40–96%) cases. Nationally, 419/764 (55%, range 37–70%) cases were recorded as having a two dilution (four-fold) or greater decrease in non-treponemal test titre within 3–6 months after treatment; not achieving this titre decrease was mainly attributable to non-attendance for follow-up and failure of titre levels to fall. Follow-up of infectious syphilis in UK genitourinary medicine clinics is poor and falls far short of that recommended by National Guidelines. Only 16 (2%) cases had follow-up at intervals approximating to 1, 2, 3, 6 and 12 months, and only 312 (40%, range 5–61%) cases attended at least two follow-up visits. Only 17 (7%) of all 236 oral treatments (including switches to oral treatment), and 33 (27%) of 123 cases with HIV infection were recorded as designated annual follow-up. Further work is needed to determine factors that account for the wide variation between regions in contact tracing and follow-up performance

The African Hospitalist Fellowship

The African Paediatric Fellowship Programme is rolling out a training course for newly qualified paediatricians to equip them with the leadership skills to function in complex general paediatric settings. The care of children in Africa carries its own unique demands, from the layering effects of multiple conditions through to establishing and sustaining services under severe resource constraints. This novel training concept aims to strengthen confidence and knowledge in areas that are not priorities during standard general paediatric training. The skills gained are considered of great relevance in assisting general paediatricians to achieve their full potential in their careers