Enhancement of ARROW Photonic Device Performance via Thermal Annealing of PECVD-based SiO2 Waveguides

Silicon-based optofluidic devices are very attractive for applications in biophotonics and chemical sensing. Understanding and controlling the properties of their dielectric waveguides is critical for the performance of these chips. We report that thermal annealing of PECVD-grown silicon dioxide (SiO2) ridge waveguides results in considerable improvements to optical transmission and particle detection. There are two fundamental changes that yield higher optical transmission: (1) propagation loss in solid-core waveguides is reduced by over 70%, and (2) coupling efficiencies between solid- and liquid-core waveguides are optimized. The combined effects result in improved optical chip transmission by a factor of 100-1000 times. These improvements are shown to arise from the elimination of a high-index layer at the surface of the SiO2 caused by water absorption into the porous oxide. The effects of this layer on optical transmission and mode confinement are shown to be reversible by alternating subjection of waveguides to water and subsequent low temperature annealing. Finally, we show that annealing improves detection of fluorescent analytes in optofluidic chips with a signal-to-noise ratio improvement of 166x and a particle detection efficiency improvement of 94%.

Intra-ocular pressure changes in patients with glaucoma. Comparison between the laryngeal mask airway and tracheal tube

We performed a randomised prospective study in 20 patients with glaucoma to examine the effects of tracheal intubation and laryngeal mask insertion on intra-ocular pressure, mean arterial blood pressure and heart rate. After induction of anaesthesia with propofol, intra-ocular pressure decreased significantly below baseline values in both the laryngeal mask and tracheal tube groups. After insertion of the laryngeal mask, intra-ocular pressure remained significantly below baseline values in all patients. In contrast, tracheal intubation was associated with a significant increase in intra-ocular pressure to above baseline values in three out of eight patients. Insertion of the laryngeal mask had minimal effects on mean arterial blood pressure and heart rate, whereas tracheal intubation significantly increased both factors relative to pre-intubation values.

A randomized trial of late reperfusion therapy for acute myocardial infarction. Thrombolysis and Angioplasty in Myocardial Infarction-6 Study Group

BACKGROUND

Experimental and observational clinical studies of acute coronary occlusion have suggested that late reperfusion prevents infarct expansion and facilitates myocardial healing. The purpose of this trial was to assess whether infarct vessel patency could be achieved in late-entry patients and what benefit, if any, can be demonstrated.

METHODS AND RESULTS

In a double-blind fashion, 197 patients with 6 to 24 hours of symptoms and ECG ST elevation were randomly assigned to tissue-type plasminogen activator (100 mg over 2 hours) or placebo. Coronary angiography within 24 hours was used to determine infarct vessel patency status. Patients with infarct-related occluded arteries were then eligible for a second randomization to either angioplasty (34 patients) or no angioplasty (37 patients). Ventricular function and cavity size were reassessed at 1 month by gated blood pool scintigraphy and at 6 months by repeat cardiac catheterization. The primary end point, infarct vessel patency, was 65% for plasminogen activator patients compared with 27% in the placebo group (p less than 0.0001). There were no differences between these groups in ejection fraction or infarct zone regional wall motion at 1 or 6 months. At 6 months, infarct vessel patency was 59% in both groups. In the placebo group, there was a significant increase in end-diastolic volume from acute phase of 127 ml to 159 ml at 6-month follow-up (p = 0.006) but no increase in cavity size for the plasminogen activator group patients. Coronary angioplasty was associated with an initial 81% recanalization success and improved ventricular function at 1 month, but by late follow-up no advantage could be demonstrated for this procedure, and there was a 38% spontaneous recanalization rate in the patients assigned to no angioplasty.

CONCLUSIONS

The study demonstrates that it is possible to achieve infarct vessel recanalization in the majority of late-entry patients with either thrombolytic therapy or angioplasty. Thrombolytic intervention had a favorable effect on prevention of cavity dilatation and left ventricular remodeling, but there are no late benefits on systolic function after thrombolysis or coronary angioplasty. The conclusions concerning overall potential benefit of applying late reperfusion therapy will require data from large-scale trials designed to assess mortality reduction.

General practitioners' subjective experience of surgery workload

General practitioners (GPs) in the U.K. frequently cite heavy workload as a major source of work-related stress. However, there is little direct evidence either to support this claim or to suggest whether the source of this stress lies in the amount, or rather the type, of work undertaken. The present paper uses a within-subjects design to address these issues in the surgery context. Over a two-week period three GPs gave ratings of subjective workload following each of their surgeries (N = 20-23). Correlational analysis showed a wide range of surgery characteristics to predict the GPs' reactions, including the length of surgeries, the number of consultations, the number of re-presentations, and the number of follow-ups and investigations requested. The GPs' perceptions of their patients (e.g. in terms of their health status and the appropriateness of the consultation), in contrast, did not emerge as significant predictors. The results of multiple regression analyses, however, revealed that most of the first-order effects could be accounted for by surgery length. Thus while the study supported the hypothesised link between the overall level of surgery work demands and the subjective experience of workload, it failed to confirm any consistent additional effects of the type of work involved. It was also found that as the length of surgeries increased, the GPs were more likely to arrange follow-up appointments. The implications of the present findings are therefore two-fold.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of computer use in the consultation on the delivery of care

The effects of the use of a computer on the delivery of care in consultations in general practice were examined. In this trial a computer system provided for the review and update of patients' medical histories, notes on doctor-patient contacts, and information on repeat prescribing. Thirty consultations in which the computer system was used and 30 consultations in which no computer was used were matched individually for the doctor consulted, the sex and age of the patient, and the presenting problem(s). Six independent general practitioners blind rated each consultation for the standard of care attained. A minor negative effect of computer use on the doctors' clinical performance was found. We suggest, however, that this small effect would disappear if a computer system was used routinely.

Confirmatory identification of Neisseria gonorrhoeae by slide coagglutination

Neisseria gonorrhoeae was identified by the Phadebact gonococcus test, a rapid slide coagglutination technique, and the results obtained were compared with those obtained by conventional methods (Gram stain morphology, oxidase reaction, and carbohydrate utilization tests) for the confirmatory identification of gonococci. Of 308 clinical isolates examined, the coagglutination procedure correctly identified 97.8% of the isolates tested as N. gonorrhoeae and 93.9% of other bacteria as not N. gonorrhoeae. The coagglutination procedure also identified 29 laboratory strains correctly as not N. gonorrhoeae. The slide coagglutination test is easy to perform and offers a valuable alternative to other techniques for the confirmatory identification of N. gonorrhoeae.