Plasma temperature measurement with a silicon photomultiplier (SiPM).

The temperature of a nonneutral plasma confined in a Penning-Malmberg trap can be determined by slowly lowering one side of the trap's electrostatic axial confinement barrier; the temperature is inferred from the rate at which particles escape the trap as a function of the barrier height. In many experiments, the escaping particles are directed toward a microchannel plate, and the resulting amplified charge is collected on a phosphor screen. The screen is used for imaging the plasma but can also be used as a Faraday cup (FC) for a temperature measurement. The sensitivity limit is then set by microphonic noise enhanced by the screen's high-voltage bias. Alternately, a silicon photomultiplier (SiPM) can be employed to measure the charge via the light emitted from the phosphor screen. This decouples the signal from the microphonic noise and allows the temperature of colder and smaller plasmas to be measured than could be measured previously; this paper focuses on the advantages of a SiPM over a FC.

Asthma in children with sickle cell disease and its association with acute chest syndrome.

BACKGROUND: Pulmonary complications are a major cause of morbidity and mortality in sickle cell disease (SCD). The relationship of asthma with SCD and acute chest syndrome (ACS) remains uncertain. A study was undertaken to test the hypotheses that asthma and bronchial hyperreactivity (BHR) are more common in children with SCD than in ethnic matched controls and that SCD children with atopic asthma are more likely to have recurrent episodes of ACS. METHODS: A modified International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire was administered and skin prick tests undertaken in 80 children with SCD and 80 ethnic matched controls aged 5-10 years. BHR was assessed by measurement of forced expiratory volume in 1 second before and after a bronchodilator (albuterol 200 mug) or an exercise challenge. RESULTS: Asthma (48% v 22%, p = 0.002) and BHR (p = 0.02) but not atopy were more common in children with SCD than in controls. Atopy (66.6% v 29%, p = 0.007) and asthma (80% v 40%, p = 0.005), particularly atopic asthma (53% v 12%, p<0.001), were more common in children with SCD who had suffered recurrent episodes of ACS than in those who had suffered a single or no episode. CONCLUSIONS: Asthma and BHR are more common in children with SCD than in ethnic matched controls, and atopic asthma appears to be associated with recurrent ACS. Early and effective anti-asthma therapy might reduce the pulmonary morbidity associated with SCD.

Activation of c-Jun N-terminal kinase in A549 lung carcinoma cells by sodium dichromate: role of dissociation of apoptosis signal regulating kinase-1 from its physiological inhibitor thioredoxin.

Changes in the components of the Jun N-terminal kinase (JNK) signalling pathway were investigated in human A549 lung carcinoma cells treated with sodium dichromate. Sodium dichromate (100 microM, 0-6h) failed to activate nuclear factor kappa B (NF-kappaB) as determined by a lack of nuclear translocation of p65 but resulted in Jun N-terminal kinase activation as assessed by phospho-Jun N-terminal kinase Western blotting in a dose-dependent (>25 microM) and time-dependent (>1h) manner. In addition, c-Jun, a downstream target of Jun N-terminal kinase signalling was also activated with a similar dose- and time-dependency at the level of both protein expression and degree of phosphorylation. In contrast, sodium dichromate treatment had no effect on levels of phospho-p38. Immunoprecipitation demonstrated that apoptosis signal regulating kinase-1 (ASK-1), an upstream activator of Jun N-terminal kinase was dissociated from its inhibitory partner thioredoxin (Trx) in response to sodium dichromate (100 microM, 4h) treatment. This treatment was also associated with a transient (2h) increase in cytosolic levels of thioredoxin but no nuclear translocation of thioredoxin was observed. In conclusion, sodium dichromate had a stimulatory effect on the Jun N-terminal kinase signalling pathway in A549 cells, resulting in activation of downstream effector molecules. We hypothesise that dissociation of apoptosis signal regulating kinase-1 from thioredoxin may be at least partially responsible for Jun N-terminal kinase activation.

Survival estimates for patients with homozygous sickle-cell disease in Jamaica: a clinic-based population study.

BACKGROUND: Information about life expectancy of patients with homozygous sickle-cell disease is needed for research and patient counselling. Our aim was to study two Jamaican populations, one clinic-based and one birth cohort and, by careful consideration of data quality and statistical analysis, to identify ways to increase the chances of obtaining valid and generalisable results. METHODS: We investigated the survival experience of 3301 patients with homozygous sickle-cell disease attending the Jamaican sickle-cell clinic between Jan 1, 1987, and Dec 31, 1996. We applied and assessed a simulation technique for incorporating early life mortality using a birth cohort, and analysed the precision of this technique. Kaplan-Meier survival estimates are produced. FINDINGS: 290 of the 3301 patients died. Median survival calculated with the excess mortality rate simulation data was 53 years (95% CI 49.3-57.0) for men and 58.5 (55.1-67.5) for women. INTERPRETATION: Our simulation technique, with realistic assumptions based on empirical evidence, offers a new estimate of median survival for patients with homozygous sickle-cell disease. We present the precision of these survival estimates, which introduces an important level of uncertainty. The inherent biases of clinically ascertained populations of patients, and the assumptions underlying analysis techniques are crucial features of survival studies in sickle-cell disease, and can modify summary statistics substantially.

Implementing a bladder ultrasound program.

Many patients admitted to an inpatient rehabilitation setting experience alteration in urinary elimination as a result of neurological changes. Urinary retention can develop due to hypotonic bladder, increased sphincter tone, absent or decreased sensation of bladder fullness, or urethral blockage. Incomplete bladder emptying can lead to such complications as urinary infection and incontinence. Rehabilitation nurses must assess patients for alterations in bladder emptying. The use of bladder ultrasound is one method now available for noninvasive measurement of bladder volume. In this article, the author reviews the implementation and results of a bladder ultrasound program at one rehabilitation facility.

The use of porous glass beads in the separation and purification of ruthenium complexes with large organic ligands.

For complexes of highly-charged transition metal cations with large organic ligands, the use of glass beads as a chromatographic support allows the ready isolation of analytically pure samples of species which tend to decompose readily on more traditional supports. The method has been used in the purification of binuclear ruthenium complexes which are usually contaminated with a small amount of the monomer, and in the purification of ferrocene-ruthenium complexes which are difficult to separate from polymeric ferrocene residues.