Development of a scalable image formation pipeline for multiscale gigapixel photography.

We report on the image formation pipeline developed to efficiently form gigapixel-scale imagery generated by the AWARE-2 multiscale camera. The AWARE-2 camera consists of 98 "microcameras" imaging through a shared spherical objective, covering a 120° x 50° field of view with approximately 40 microradian instantaneous field of view (the angular extent of a pixel). The pipeline is scalable, capable of producing imagery ranging in scope from "live" one megapixel views to full resolution gigapixel images. Architectural choices that enable trivially parallelizable algorithms for rapid image formation and on-the-fly microcamera alignment compensation are discussed.

Multiscale gigapixel photography.

Pixel count is the ratio of the solid angle within a camera's field of view to the solid angle covered by a single detector element. Because the size of the smallest resolvable pixel is proportional to aperture diameter and the maximum field of view is scale independent, the diffraction-limited pixel count is proportional to aperture area. At present, digital cameras operate near the fundamental limit of 1-10 megapixels for millimetre-scale apertures, but few approach the corresponding limits of 1-100 gigapixels for centimetre-scale apertures. Barriers to high-pixel-count imaging include scale-dependent geometric aberrations, the cost and complexity of gigapixel sensor arrays, and the computational and communications challenge of gigapixel image management. Here we describe the AWARE-2 camera, which uses a 16-mm entrance aperture to capture snapshot, one-gigapixel images at three frames per minute. AWARE-2 uses a parallel array of microcameras to reduce the problems of gigapixel imaging to those of megapixel imaging, which are more tractable. In cameras of conventional design, lens speed and field of view decrease as lens scale increases, but with the experimental system described here we confirm previous theoretical results suggesting that lens speed and field of view can be scale independent in microcamera-based imagers resolving up to 50 gigapixels. Ubiquitous gigapixel cameras may transform the central challenge of photography from the question of where to point the camera to that of how to mine the data.

Postoperative pain control using epidural catheters after anterior spinal fusion for adolescent scoliosis.

STUDY DESIGN: A prospective review of patients undergoing epidural catheter placement after anterior spinal fusion and instrumentation for adolescent scoliosis was performed. Data were collected using visual analog pain scores reflecting the patients' perception of their pain control. OBJECTIVES: To present the authors' technique for epidural catheter placement and dosing protocol, and to demonstrate the results from postoperative pain control after anterior spinal instrumented fusion for 10 consecutive patients. SUMMARY OF BACKGROUND DATA: The literature regarding the benefits of epidural catheters after spinal surgery is contradictory, even with controlled studies comparing epidural catheters with intravenous morphine patient-controlled anesthesia. The authors believe that this lack of consensus stems from varied epidural dosing protocols and techniques in catheter placement, which they have witnessed anecdotally at their own institution. This prompted the authors to develop and refine a standardized dosing and catheter placement protocol for pain control after spinal surgery. METHODS: Epidural catheters were placed intraoperatively before wound closure, then removed on postoperative Day 5. Dosing consisted of fentanyl (1 microg/kg) and hydromorphone (5 microg/kg) diluted in preservative-free saline (0.2 mL/kg). After surgery, dosing consisted of 0.1% ropivacaine and hydromorphone (10 microg/ml) continuously infused at 0.2 mL/kg/hour. Postoperative pain control was assessed on each postoperative day using a visual analog pain scale with choices ranging from 0 to 10. RESULTS: The arithmetic mean of the median pain scores after surgery was 2.1. The mean of the maximum pain scores for the 5 days was 4.1. Three patients required an epidural bolus and a 20% increase in the epidural infusion rate. One patient was judged to be excessively sleepy, so the epidural infusion rate was decreased by 20%. Pruritus requiring diphenhydramine developed in three patients. No other adverse effects related to epidural analgesia were noted. No catheters were accidentally pulled out or disconnected. CONCLUSION: By following the dosing protocol described, epidural catheters can be used safely and effectively to control postoperative pain after anterior instrumentation and spinal fusion for adolescent scoliosis.

A dual epidural catheter technique to provide analgesia following posterior spinal fusion for scoliosis in children and adolescents.

BACKGROUND: The authors report their experience with the use of a dual epidural catheter technique in controlling pain following long posterior spinal fusion and instrumentation for scoliosis in children and adolescents. METHODS: Following completion of the surgical procedure and prior to wound closure, the upper catheter was inserted with the tip directed cephalad to T1-4 while the tip of the lower catheter was positioned at the L1-4 level. As the surgical wound was being closed, the catheters were dosed with fentanyl and hydromorphone followed by a continuous infusion of ropivacaine plus hydromorphone. Postoperative pain was assessed every 2-4 h using a visual analogue score or an observational behavioural score (0=no pain, 10=worst imaginable pain). There were 14 patients ranging in age from 5-17 years (12.7 +/- 3.5) and in weight from 19-68 kg (44.3 +/- 17.5). The epidural catheters were left in place until the fifth postoperative day. RESULTS: The mean of the median pain score from each patient was 1.5 +/- 1.6, 1.6 +/- 1.5, 1.4 +/- 1.3, 1.1 +/- 1.1 and 0.9 +/- 0.9, respectively, on postoperative days 1 through 5. The mean of the maximum pain scores was 3.5 +/- 2.3 (range 0-7), 4 +/- 1.6 (range 2-6), 3.1 +/- 1.7 (range 1-6), 2.4 +/- 1.5 (range 0-4) and 2.2 +/- 1.4 (range 0-4), respectively, on postoperative days 1 through 5. CONCLUSION: No adverse effects related to epidural analgesia were noted.

Using healthy life years (HeaLYs) to assess programming needs in a public health unit.

In December 1997, public health units in Ontario received revised mandatory program guidelines from the Ministry of Health in advance of the downloading of public health to municipalities. Public health units face difficult decisions in allocating municipal resources to meet the Province's mandated programs. To set priorities for resource allocation, it is critical to assess need across program areas and to use a common unit in doing so. This paper applies the Healthy Life Years (HeaLYs) method in assessing health need related to the mandatory programs for the population of Wellington and Dufferin counties in Ontario. The HeaLYs method incorporates duration and severity of ill-health, incidence and mortality in calculating years of healthy life lost (YHLL). For Wellington-Dufferin, the leading causes of YHLL were concentrated in the program areas of chronic disease, injury, and substance abuse and included four areas not addressed in the MPG (suicide, depression, dementia, and osteoarthritis).

Outbreak of trichinosis in Ontario secondary to the ingestion of wild boar meat.

We report an outbreak of trichinosis from the consumption of locally processed, cold smoked wild boar meat of a domestically reared animal from a farm in Dufferin County, Ontario. Between January and March 1993, 24 cases of trichinosis were identified and of these, 21 patients were symptomatic. The most common symptoms were myalgia (75%), weakness (75%), fever (71%) and periorbital edema (67%). Eosinophilia and elevated creatine phosphokinase levels were noted in 86% and 89% of patients respectively. Trichinella serology was positive in 55%. Two patients were hospitalized, one with severe diarrhoea and another with myalgia and fever. Several patients appeared to improve temporarily after treatment with albendazole. This outbreak reminds us that although trichinosis is rare in Ontario, physicians must maintain a high index of suspicion for the disease. To prevent further outbreaks, the Ontario Government has instituted new guidelines for the processing of all wild boar meat.

Intrathecal morphine (ITM) for postoperative pain control in children: a comparison with nalbuphine patient controlled analgesia (PCA).

This is a retrospective study covering the ten-year period 1984-1993. Single shot spinal morphine (ITM) is compared with PCA nalbuphine for postoperative pain relief in children having abdominal or thoracic procedures. The records of 52 patients meeting selection criteria were examined. Nursing and physician notations were reviewed for hourly pain assessments, evidence of associated complications, respiratory depression, nausea and or vomiting, pruritus, and urinary retention. ITM provided significantly better pain relief (2.2 h in pain) during the first 24 h postoperatively than PCA nalbuphine (9.2 h in pain). With the exception of urinary retention which was significantly more frequent following ITM (58.6%) compared to PCA nalbuphine (8.7%), narcotic related complications were not different between the two groups. No difference in duration of hospital stay or ICU stay could be demonstrated. We conclude that ITM provides better pain relief, without more serious complications, than PCA nalbuphine. We recommend it as a safe, effective technique to treat postoperative pain in children following thoracic or upper abdominal procedures.

Occupational exposure to Mycobacterium bovis infection in deer and elk in Ontario.

In late 1991, two herds of deer and elk were depopulated at a slaughtering plant in Ontario, followed by processing of infected animals at a rendering plant. We conducted a questionnaire plus tuberculin skin-test survey of 104 exposed slaughtering and rendering plant workers, and government veterinarians and inspectors. Overall, 17 participants were skin-test positive, one of 51 initially skin-test negative subjects tested a second time three months later became positive, consistent with the risk associated with occupational exposure during the depopulation of tuberculous elk previously observed in Alberta. Deer farming is widespread, with 263 herds in Ontario. The likely route of transmission is through aerosols. Possible reasons for the low conversion rate include the use of respiratory protection, absence of a tanning plant, an enclosed rendering plant process, and late skin testing which may have underestimated the number of conversions. Recommendations for prevention are summarized; in particular, respiratory protection for work with infected herds should probably include high efficiency particulate face masks.