Excessive Strand End Slip in Prestressed Piles

This paper presents the results of a research project that investigated excessive strand end slip observed recently in some prestressed piles. From measurements taken in the field, it is apparent that the problem o excessive initial strand slip is independent of pile shape and size. Strand end slip is evident in piles of different manufacturers in different states in the Southeast. Excessive strand end slip was found in both the top and bottom of the cross section of the piles, although the top portion of the cross section generally exhibited much higher initial slip. Several preventive measures can be adopted to reduce the excessive strand end slip. These preventive measures include: a) proper concrete mixture proportioning to reduce top bar effect; b) use of higher-strength concrete with the lowest possible slump and setting time; c) assessment of the condition of the strands prior to installation to insure excellent bond characteristics; d) gradual release of prestress, with an optimal release sequence; and e) use of adequate vibration to ensure consolidation. The strand end slip measured at five prestressing plants in the Southeast is considerably higher than the allowable end slip and is expected to affect the pile performance. If the strand slip theory is adopted, the strand development length increases substantially due to the excessive strand end slip. A top bar effect factor similar to the one used in reinforced concrete design is recommended. To maintain the excellent quality of precast and prestressed concrete products, manufacturers should adopt a dynamic quality control process that follows the rapid changes in the industry. More tests are necessary to ensure excellent quality, such as the Moustafa or an equivalent test, to assess the bond capabilities of the strands, end slip measurements, and direct measurement of the transfer length. Installation of piles should proceed in a manner to alleviate the top bar effects by placing piles alternately in their best and worst directions

Building leadership capacity and future leaders in operational research in low-income countries: why and how?

Very limited operational research (OR) emerges from programme settings in low-income countries where the greatest burden of disease lies. The price paid for this void includes a lack of understanding of how health systems are actually functioning, not knowing what works and what does not, and an inability to propose adapted and innovative solutions to programme problems. We use the National Tuberculosis Control Programme as an example to advocate for strong programme-level leadership to steer OR and build viable relationships between programme managers, researchers and policy makers. We highlight the need to create a stimulating environment for conducting OR and identify some of the main practical challenges and enabling factors at programme level. We focus on the important role of an OR focal point within programmes and practical approaches to training that can deliver timely and quantifiable outputs. Finally, we emphasise the need to measure successful OR leadership development at programme level and we propose parameters by which this can be assessed. This paper 1) provides reasons why programmes should take the lead in coordinating and directing OR, 2) identifies the practical challenges and enabling factors for implementing, managing and sustaining OR and 3) proposes parameters for measuring successful leadership capacity development in OR

Passive Versus Active Tuberculosis Case Finding and Isoniazid Preventive Therapy Among Household Contacts in a Rural District of Malawi.

SETTING: Thyolo district, rural Malawi. OBJECTIVES: To compare passive with active case finding among household contacts of smear-positive pulmonary tuberculosis (TB) patients for 1) TB case detection and 2) the proportion of child contacts aged under 6 years who are placed on isoniazid (INH) preventive therapy. DESIGN: Cross-sectional study. METHODS: Passive and active case finding was conducted among household contacts, and the uptake of INH preventive therapy in children was assessed. RESULTS: There were 189 index TB cases and 985 household contacts. Human immunodeficiency virus (HIV) prevalence among index cases was 69%. Prevalence of TB by passive case finding among 524 household contacts was 0.19% (191/100000), which was significantly lower than with active finding among 461 contacts (1.74%, 1735/100000, P = 0.01). Of 126 children in the passive cohort, 22 (17%) received INH, while in the active cohort 25 (22%) of 113 children received the drug. Transport costs associated with chest X-ray (CXR) screening were the major reason for low INH uptake. CONCLUSIONS: Where the majority of TB patients are HIV-positive, active case finding among household contacts yields nine times more TB cases and is an opportunity for reducing TB morbidity and mortality. The need for a CXR is an obstacle to the uptake of INH prophylaxis

The Union and Médecins Sans Frontières approach to operational research.

Operational research (OR) has become a hot topic at national meetings, international conferences and donor fora. The International Union Against Tuberculosis and Lung Disease (The Union) and Médecins Sans Frontières (MSF) Operational Centre Brussels strongly promote and implement OR with colleagues in low- and middle-income countries. Here we describe how the two organisations define OR, and explain the guiding principles and methodology that underpin the strategy for developing and expanding OR in those countries. We articulate The Union's and MSF's approach to supporting OR, highlighting the main synergies and differences. Then, using the Malawi National Tuberculosis Control Programme as an example, we show how OR can be embedded within tuberculosis control activities, leading to changes in policy and practice at the national level. We discuss the difficult, yet vitally important, issue of capacity building, and share our vision of a new paradigm of product-related training and performance-based OR fellowships as two ways of developing the necessary skills at country level to ensure research is actually performed. Finally, we highlight the need to consider and incorporate into practice the ethical components of OR. This is a key moment to be involved in OR. We are confident that in partnership with interested stakeholders, including the World Health Organization, we can stimulate the implementation of quality, relevant OR as an integral part of health service delivery that in turn will lead to better health for people, particularly for those living in the poorer parts of the world

Nonequilibrium steady states in a vibrated-rod monolayer: tetratic, nematic and smectic correlations

We study experimentally the nonequilibrium phase behaviour of a horizontal monolayer of macroscopic rods. The motion of the rods in two dimensions is driven by vibrations in the vertical direction. Aside from the control variables of packing fraction and aspect ratio that are typically explored in molecular liquid crystalline systems, due to the macroscopic size of the particles we are also able to investigate the effect of the precise shape of the particle on the steady states of this driven system. We find that the shape plays an important role in determining the nature of the orientational ordering at high packing fraction. Cylindrical particles show substantial tetratic correlations over a range of aspect ratios where spherocylinders have previously been shown by Bates et al (JCP 112, 10034 (2000)) to undergo transitions between isotropic and nematic phases. Particles that are thinner at the ends (rolling pins or bails) show nematic ordering over the same range of aspect ratios, with a well-established nematic phase at large aspect ratio and a defect-ridden nematic state with large-scale swirling motion at small aspect ratios. Finally, long-grain, basmati rice, whose geometry is intermediate between the two shapes above, shows phases with strong indications of smectic order.Comment: 18 pages and 13 eps figures, references adde

Outcomes of tuberculosis patients who start antiretroviral therapy under routine programme conditions in Malawi

SETTING: Public sector facilities in Malawi providing antiretroviral therapy (ART) to human immunodeficiency virus (HIV) positive patients, including those with tuberculosis (TB). OBJECTIVES: To compare 6-month and 12-month cohort treatment outcomes of HIV-positive TB patients and HIV-positive non-TB patients treated with ART. DESIGN: Retrospective data collection using ART patient master cards and ART patient registers. RESULTS: Between July and September 2005, 7905 patients started ART, 6967 with a non-TB diagnosis and 938 with a diagnosis of active TB. 6-month cohort outcomes of non-TB and TB patients censored on 31 March 2006 showed significantly more TB patients alive and on ART (77%) compared with non-TB patients (71%) (P < 0.001). Between January and March 2005, 4580 patients started ART, 4179 with a non-TB diagnosis and 401 with a diagnosis of active TB. 12-month cohort outcomes of non-TB and TB patients censored on 31 March 2006 showed significantly more TB patients alive and on ART (74%) compared with non-TB patients (66%) (P < 0.001). Other outcomes of default and transfer out were also significantly less frequent in TB compared with non-TB patients. CONCLUSION: HIV-positive TB patients on ART in Malawi have generally good treatment outcomes, and more patients need to access this HIV treatment