A reader's guide to the evaluation of causation

In this article, we review the criteria used to establish a causal association. A literature search strategy will be outlined. We present a clinical scenario that was formulated to examine the evidence for nonsteroidal anti-inflammatory drugs as a possible cause of gastrointestinal ulceration and bleeding. Several of the studies identified in the literature search were critically appraised and the criteria needed to confirm a causal link were then applied. These guidelines may be employed to not only demonstrate the aetiology of a disease but have wider applicability in terms of determining whether a medication may be causing certain adverse events.     

Obstructive jaundice due to a chlorinated hydrocarbon in breast milk

A 6-week-old breast-fed infant had obstructive jaundice and hepatomegaly. When a dry-cleaning solvent, tetrachloroethylene, was detected in the mother's milk and blood, breast-feeding was discontinued. Rapid clinical and biochemical improvement followed. The child grew normally and had normal liver function during 2 years of follow-up.     

Estimation in linear time-delay system with coloured observation noise

A sequential fixed-lag smoothing algorithm is derived here for linear systems, when it is assumed that the measurements contain the sum of signals with known time delays and are corrupted by coloured noise. The innovations approach is used to derive the algorithm that is suitable for online computations.     

Effect of copper chromite and copper chromitecopper oxide mixture catalysts on the thermal decomposition of ammonium perchlorate and composite solid propellant

Thermal decomposition of powdered ammonium perchlorate (AP), polystyrene (PS) and $\text{AP}\text{PS}$ propellant, catalysed by freshly-prepared CuCr₂O₄ and mixtures of CuCr₂O₄ and CuO, has been studied with a low concentration (1% by mass) of the catalysts. It appears that decomposition is increased due to heterogeneous catalysis. The kinetics of thermal decomposition of AP in the presence of CuCr₂O₄ in the orthorhombic region of AP have also been studied.     

Activity of amoxicillin/clavulanate in patients with tuberculosis

Some beta-lactam antibiotics are active in vitro against Mycobacterium tuberculosis. There are anecdotal reports of successful treatment of tuberculosis caused by multiple-drug-resistant strains of M. tuberculosis with regimens that included amoxicillin/clavulanate. Reduction of M. tuberculosis in the sputum of patients with pulmonary tuberculosis during administration of amoxicillin/clavulanate was measured by a quantitative culture method to determine the activity in vivo. Patients were randomized to receive isoniazid, ofloxacin, or amoxicillin/clavulanate for 7 days. Isoniazid was the most effective agent, reducing M. tuberculosis after 2 days at a mean rate (+/- standard deviation) of 0.60 +/- 0.30 log10 cfu/mL per day, compared with 0.32 +/- 0.05 and 0.34 +/- 0.03 for ofloxacin and amoxicillin/clavulanate, respectively. The early bactericidal activity of amoxicillin/clavulanate was comparable to that reported for antituberculous agents other than isoniazid. Further studies of beta-lactam antibiotics with in vitro activity against M. tuberculosis are warranted to define their role in treatment of tuberculosis.     

Indigenous design and development of a micro-pulse lidar for atmospheric studies

A sophisticated micro-pulse lidar (MPL) has been designed and developed for the study of the atmospheric boundary layer (ABL) and clouds. The developed MPL uses a low energy pico-second pulsed Nd:YAG laser at 532 nm. The conventional receiver optic is used along with a photomultiplier tube in single photon detection mode. Stanford Research Systems' multi-channel scalar (MCS) is used with a personal computer for data acquisition. Due to the short laser pulse and a fast MCS, a spatial resolution of 0.75 m has been achieved. The control circuit has been designed to sense telescope cover status (open or closed) to avoid any mistakes in dark count and background data acquisition. The complete control software and Graphical User Interface (GUI) has been developed in Visual Basic. The lidar system has been tested both for its functionality to detect the variation in ABL and cloud height and also for its capability to acquire continuous night-time data without user interaction. In this article the design details and some preliminary results are discussed.