Comparing mixing and displacement ventilation in classrooms: pupils' perception and health

Several studies have found that indoor air quality (IAQ) in schools is often poor and may affect the health of the pupils. Building ventilation is a means to reduce pollutants indoors, but different designs should be evaluated for their effectiveness in different environments. In a field experiment performed at four classrooms in one school building, air was supplied either in the mixing or in the displacement mode, and we collected information on exposures, pupils' perception of IAQ and climate, and health symptoms and performed clinical examinations. The room temperature, relative humidity, concentration of CO?, and cat allergen were measured at the breathing height and were similar during each ventilation mode. The children perceived IAQ were similar in the two ventilation regimes, and there were few differences in symptom reports or clinical parameters. However, the pupils reported more eye symptoms during displacement ventilation. PRACTICAL IMPLICATIONS: Both mixing and displacement ventilation may be appropriate in school classrooms as long as the overall design, ventilation rates, and maintenance of systems are satisfactory.     

Doctors'' attitudes to fibromyalgia: a phenomenological study

BACKGROUND: Primary systemic amyloidosis is an uncommon disorder associated with the desposition of fragments of immunoglobulin light chains in a variety of tissues. Some patients present with peripheral neuropathy. The prognosis of these patients is not clear. METHODS: We searched the medical records of all patients seen at the Mayo Clinic between January 1, 1978 and December 31, 1994 with the diagnosis of amyloidosis. Twenty-six patients with sural nerve biopsy-proven amyloid neuropathy and a documented monoclonal protein in the serum or urine were studied. RESULTS: The most common symptoms that led to the diagnosis of primary amyloid neuropathy were paresthesias (81%), muscle weakness (65%), and numbness (58%). The median duration of symptoms before diagnosis was 29 months. Symptoms of autonomic neuropathy were present at diagnosis in 17 patients (65%). Other organs were involved in most patients. The monoclonal light chain protein detected was lambda in 18 patients (69%) and kappa in 8 (31%). The neuropathy was chronic, debilitating, and showed relentless progression. Twenty-two patients (85%) died (median survival 25 months) and 4 patients were alive at a median follow-up of 4.5 years. Progressive amyloidosis was the cause of death in most patients. Survival was significantly better in the patients with a serum albumin level >3 g/dL (median survival 31 months compared with 18 months; P <0.01, log-rank test). CONCLUSIONS: Patients with primary systemic amyloidosis in whom neuropathy is the dominant clinical manifestation often do not receive a diagnosis until years after the onset of symptoms. The prognosis is worse than previously indicated. Neuropathy does not improve with therapy.     

Intermediates in the Methanol-to-hydrocarbons (MTH) Reaction: A Gas Phase Study of the Unimolecular Reactivity of Multiply Methylated Benzenium Cations

In order to reach a deeper insight into the reaction mechanism of the zeolite catalyzed methanol to hydrocarbons reaction (MTH), the proposed reaction intermediates, i.e., a series of multiply methyl-substituted benzenium ions has been generated in the gas phase by chemical ionization. The fragmentations of the corresponding long-lived (metastable) ions have been investigated. While expulsion of H₂ dominates for the lower homologues, elimination of methane dominates for the higher homologues, accompanied by increasing amounts CH₃^·. Loss of larger fragments relevant to the MTH-reaction, in particular ethene, propene and even butene, is also observed in minor amounts. This latter finding is consistent with a proposed reaction cycle in the MTH reaction known as the paring mechanism, and the feasibility of this mechanism has thus been demonstrated. The metastable gas-phase ions studied here are considerably more energetic than those residing in a zeolite catalyst, but they were found to decompose with markedly higher selectivity towards alkenes as compared to those activated by collision-induced dissociation (CID).     

125I-labelling of an internally 75Se-labelled monoclonal antibody--biodistribution in tumour-bearing nude mice

A monoclonal antibody, C215, was first internally labelled with 75Se-methionine and then labelled with 125I. The biodistribution of the dual-labelled [125I][75Se]C215 was studied in tumour-bearing nude mice killed 3 days after injection. The biodistribution of the dual-labelled [125I][75Se]C215 was compared with the biodistribution of single-labelled [131I]C215 and [75Se]C215. Iodine-labelled antibodies seem to be damaged during iodination, affecting the disappearance rate and tumour uptake. There were no signs of dehalogenation of circulating antibodies or antibodies taken up in the tumour.     

Accuracy of employee reports on changes in pay.

To test the validity of perceived change measures, questionnaires were administered to 246 employees before and after automation. Actual and perceived change in pay was the one aspect of change studied. "Data are presented on the degree of accuracy of employee reports, on the nature of the deviations between reports and actuality, and on the relationship of the deviations to potential explanatory variables." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Risk factors for chronic graft-versus-host disease after bone marrow transplantation: a retrospective single centre analysis

We retrospectively compared the changes in serum albumin concentration and colloid osmotic pressure between survivors and nonsurvivors of prolonged (> or = 7 days) critical illness over a 2-year period from 1 July 1995. All patients had serum albumin measured daily, and colloid osmotic pressure measured 5 days a week, throughout their ICU admission. They received crystalloid and colloid infusions as well as parenteral or enteral feeding. Infusions of albumin were not used to treat hypoalbuminaemia. One hundred and forty-five patients were included, 66 nonsurvivors and 79 survivors. Nonsurvivors were significantly older than survivors [mean (95% CI): 58 (3.8) and 49 (4.1) years, respectively] and had a greater risk of death [mean (95% CI): 0.44 (0.06) and 0.28 (0.05); p < 0.05]. There was no significant difference in gender, APACHE II score [mean (95% CI): 22 (2.7) (nonsurvivors); 18 (2.3) (survivors)] or length of stay [median (interquartile range): 14 (9-27) days (nonsurvivors); 15 (9-26) days (survivors)]. There was no difference between the two groups in the absolute minimum serum albumin concentrations reached, the time to reach that minimum or the minimum in the first 7 days. However, nonsurvivors had a significantly lower mean serum albumin concentration: [mean (95% CI): 15.7 (5.1) g.l-1 compared with 18.3 (4.6) g.l-1 in survivors; p < 0.05]. They also had a lower recovery mean (the weighted mean after the minimum value): [mean (95% CI): 13.3 (5.1) g.l-1 (nonsurvivors) and 18.6 (5.3) g.l-1 (survivors); p < 0.01]. Analysis of colloid osmotic pressure results showed no difference between the groups in mean, minimum or recovery mean. Regression analysis of mean colloid osmotic pressure and albumin revealed that albumin only contributed 17% of the colloid osmotic pressure in these patients. The similar decrease in albumin in nonsurvivors and survivors may reflect the acute inflammatory response and/or haemodilution. However, survivors showed an ability to increase serum albumin concentrations, possibly owing to resumption of synthesis. The colloid osmotic pressure varied little between or within either group of patients, possibly because of the use of artificial colloids. There was no relationship between death and colloid osmotic pressure.     

212 transmission electron microscopy applied to phase transformations in ball bearings

$\text{2}\text{1}\text{2}$D transmission electron microscopy has been applied to rolling contact-fatigued ball bearings. The $\text{2}\text{1}\text{2}$D technique implies that correlations between image features and the object lattice structure are transformed to a stereoscopic effect, using defocused dark-field image pairs. During contact fatigue, the martensite matrix may decay and be transformed to new phases. Particularly, a carbon-enriched phase has been studied. The findings indicate areas of probable nucleation sites and areas being dilated due to internal stresses. The phase is constituted of a lattice structure with minor and regular variations in the g-vector, involving vector orientation and magnitude.     

Inter-observer variation in masked and unmasked images for quality evaluation of clinical radiographs

PURPOSE: To investigate the influence of masking on the inter-observer variation in image quality evaluation of clinical radiographs of chest and lumbar spine. BACKGROUND: Inter-observer variation is a big problem in image quality evaluation since this variation is often much bigger than the variation in image quality between, for example, two radiographic systems. In this study, we have evaluated the effect of masking on the inter-observer variation. The idea of the masking was to force every observer to view exactly the same part of the image and to avoid the effect of the overall 'first impression' of the image. A discussion with a group of European expert radiologists before the study indicated that masking might be a good way to reduce the inter-observer variation. METHODS: Five chest and five lumbar spine radiographs were collected together with detailed information regarding exposure conditions. The radiographs were digitised with a high-performance scanner and five different manipulations were performed, simulating five different exposure conditions. The contrast, noise and spatial resolution were manipulated by this method. The images were printed onto the film and the individual masks were produced for each film, showing only the parts of the images that were necessary for the image quality evaluation. The quality of the images was evaluated on ordinary viewing boxes by a large group of experienced radiologists. The images were examined with and without the masks with a set of image criteria (if fulfilled, 1 point; and not fulfilled, 0 point), and the mean score was calculated for each simulated exposure condition. RESULTS: The results of this study indicate that-contrary to what was supposed-the inter-observer variation increased when the images were masked. In some cases, especially for chest, this increase was statistically significant. CONCLUSIONS: Based on the results of this study, image masking in studies of fulfilment of image criteria cannot be recommended.