Modulational instability in a silicon-on-insulator directional coupler: role of the coupling-induced group velocity dispersion.

We report frequency conversion experiments in silicon-on-insulator (SOI) directional couplers. We demonstrate that the evanescent coupling between two subwavelength SOI waveguides is strongly dispersive and significantly modifies modulational instability (MI) spectra through the coupling induced group velocity dispersion (GVD). As the separation between two 380-nm-wide silicon photonic wires decreases, the increasing dispersion of the coupling makes the GVD in the symmetric supermode more normal and suppresses the bandwidth of the MI gain observed for larger separations.

A comparison of classroom and distance learning techniques for rural EMT-I instruction.

OBJECTIVES: To determine whether two different distance learning techniques are as effective as classroom teaching for training rural-based emergency medical technician-intermediate (EMT-I) students. METHODS: A prospective, nonrandomized comparison of three different instructional methods, with the outcome measurements being mean test scores and attrition rates, was devised. Fifty-seven EMT-I students from rural communities in central Texas were assigned to one of three groups. Each group received 50 hours of didactic instruction based on the U.S. Department of Transportation EMT-I curriculum. The same instructor taught all classes, and all groups used the same workbooks, syllabi, and computer-based tutorials. Group 1 (n = 25) received traditional classroom instruction. Group 2 (n = 18) received instruction using a two-way audio/graphic computer network. Group 3 (n = 14) received instruction using a satellite-based audio/video networks. All students then took a standardized multiple-choice examination. Attrition rates were based on the number of those who qualified for EMT-I certification. RESULTS: Mean test results for each group were as follows: group 1, 93 (95% CI = 91-95); group 2, 94 (95% CI = 93-96); group 3, 94 (95% CI = 92-96). No significant difference was noted in mean test scores between groups (p = 0.21). Attrition rates were as follows: group 1, 88% (95% CI = 69-97%); group 2, 100% (95% CI = 81-100%); group 3, 86% (95% CI = 57-98%). No significant difference was seen in attrition rates between groups (p = 0.24). CONCLUSIONS: No difference was found in mean test scores or attrition rates between traditional classroom and two distance learning methods for rural-based EMT-I students. Distance learning techniques may offer an effective alternative for providing educational opportunities to rural EMS providers.

Underrecognition of cervical Neisseria gonorrhoeae and Chlamydia trachomatis infections in the emergency department.

OBJECTIVES: 1) To quantify the frequency of underrecognized Neisseria gonorrhoeae and Chlamydia trachomatis cervical infections in women tested in the ED, 2) to describe and compare the characteristics of those treated and not treated during the initial visit, and 3) to quantify the delay interval until treatment was provided. METHODS: A 2-year, retrospective consecutive case series was performed from June 1, 1992, to May 31, 1994. There were 148 women with > or = 1 discrete occurrence of culture-proven cervical N. gonorrhoeae or C. trachomatis infection studied. All the patients were evaluated in a university-affiliated, tertiary care hospital-based ED with a large rural referral area. The main outcome measures were the proportions of patients with positive cultures both treated and not treated in the ED, the clinical characteristics of each group, and the proportion remaining untreated or experiencing treatment delays of > 2 weeks after attempted phone, mail, and public health follow-up. RESULTS: Of 157 occurrences of positive cultures for N. gonorrhoeae or C. trachomatis, 86 (53%) were treated with a regimen suggested by the CDC prior to ED release. The proportion of women with isolated C. trachomatis infections that were underrecognized and untreated initially was larger than the proportions with isolated N. gonorrhoeae or combined infections (79% vs 27% and 53%, respectively, p < 0.0001). Women with findings suggestive of advanced disease (history of fever or chills, or examination evidence of temperature > 38 degrees C, purulent vaginal discharge, or any uterine/salpinx/ovarian tenderness) were more often recognized and treated with appropriate antibiotics initially (p = 0.02 to < 0.00001 for all). After phone, mail, and public health follow-up, treatment could not be documented for 25% of the occurrences, in all cases due to an inability to locate the patient. An additional 20% of the women did not receive treatment for 14-60 days. CONCLUSIONS: In this population, both N. gonorrhoeae and C. trachomatis cervical infections are frequently underrecognized in the ED, with isolated C. trachomatis infections associated with significantly higher proportions of underrecognition. Many affected women remain untreated for extended intervals, creating public and individual health risks. Improved point of contact detection, follow-up, and treatment policies are needed to limit these risks.

Comparison of hyperbaric oxygen and dapsone therapy for loxosceles envenomation.

OBJECTIVE: To determine whether hyperbaric O2 (HBO), dapsone, or HBO plus dapsone affects lesion size in a swine model of Loxosceles envenomation. METHODS: In a randomized controlled animal laboratory experiment, 32 piglets were assigned to 1 of 4 equal groups. Each piglet received 15 microliters, of purified venom intradermally on day zero. Group 1 received no treatment; group 2 received HBO at 2 atm for 2 hours on days 1-3; group 3 received 50 mg of dapsone orally on days 1-3; and group 4 received dapsone 50 mg orally and HBO at 2 atm for 2 hours on days 1-3. On days 1-7, 14, and 21, an investigator blinded to the treatment groups measured necrosis and induration. Mean necrosis and induration rates were compared using analysis of variance for repeated measures. RESULTS: Comparing groups on any day, no significant difference was noted in necrosis, induration, reduction in necrosis from day 1, or rate of change in lesion size from days 1-7. A difference was seen in the reduction of induration between all 3 treatment groups and the control group on days 7 and 14 only. The sample size permitted a power of 0.8 to detect a 12-mm mean change in lesion size. CONCLUSION: Compared with the control, neither dapsone, HBO, nor the combination of dapsone and HBO reduced necrosis from Loxosceles envenomation on days 3-21. An increase was seen in the rate of reduction in induration between all 3 treatment groups and the control group on days 7-21. However, the magnitude of this effect was clinically insignificant. In this animal model, treatment with either dapsone or HBO or a combination offers little clinical benefit in Loxosceles envenomation.

Development of an acute cutaneous swine model for Loxosceles envenomation.

STUDY OBJECTIVE: To develop an acute cutaneous swine model for Loxosceles envenomation which could be used to objectively compare various treatment modalities. PARTICIPANTS: Nine weanling, mixed-breed domestic piglets. INTERVENTIONS: Piglets were injected intradermal in the hindlimb with Loxosceles deserta venom in increasing doses and concentrations until consistently large lesions were obtained. A minimum of 3 injections/venom preparation were carried out, with no more than 2 injections/animal. Repeat injections in the same animal were separated by 8 d. MEASUREMENTS AND MAIN RESULTS: All lesions were measured daily for erythema and necrosis for 7 consecutive days. Data are reported as individual and mean maximal values. The piglets receiving 0.1, 0.2 or 0.3 ml of 5 microliters venom/ml saline developed small inconsistent lesions, with the largest necrotic lesion 5 mm. Those injected with 0.3 ml of venom diluted 15 microliters/ml saline developed small necrotic lesions (mean 4 mm, maximal 10 mm). All piglets injected with 25 microliters of venom diluted to 0.3 ml developed large necrotic lesions (mean 33 mm) with substantial erythema (mean 177 mm). CONCLUSION: Intradermal injection of 0.1 ml of 25 microliters purified Loxosceles deserta venom diluted to 0.3 ml with sterile saline produced large necrotic lesions in piglets. This model may be used to study Loxosceles envenomation and treatment.

Equestrian injuries: a five-year review.

A retrospective chart review was conducted to define the demographic and injury patterns of patients presenting to the emergency department (ED). The setting is a rural/small urban tertiary care center with approximately 40,000 visits per year. All patients presenting to the ED from January 1986 through December 1990 with equestrian-related injuries were enrolled in the study. Measurements included age, sex, mechanism of injury, injury or injuries diagnosed, admission to the hospital, morbidity, and mortality. A total of 142 patients met the inclusion criteria. The majority of injuries occurred when the patient fell from a horse. There were also a large number of injuries associated with handling the horse. Most injuries were minor, but 15% required hospital admission. There were no deaths. In conclusion, equestrian activities are associated with a risk of serious injury to both riders and handlers of horses. Education of both the public and primary care physicians should focus on injury prevention.

Intranasal midazolam as a sedative for children during laceration repair.

We performed a retrospective chart review to determine the onset, duration, safety, and clinical sedative effects of 0.2 to 0.5 mg/kg intranasal midazolam in young children during laceration repair. Of 408 children treated for lacerations during an 8-month period, 42 (10%) received intranasal midazolam. Documentation was adequate for detailed analysis in 40 cases. Data are reported as mean +/- standard deviation and the frequency with 95% confidence limit (CL) estimates. The mean age of the study population was 32 +/- 9 months (range 12 months to 6 years), and the mean body mass was 14.5 +/- 3 kg. Topical or injected local anesthesia was used in 37 cases. Overall, 73% (CL 56% to 85%) of the children achieved adequate sedation. However, those receiving 0.2 to 0.29 mg/kg had adequate sedation in only 27% (CL 6% to 60%) of the cases compared with 80% (CL 52% to 95%) and 100% (CL 79% to 100%) when 0.3 to 0.39 and 0.4 to 0.5 mg/kg respectively were administered. When achieved, sedation occurred within 12 +/- 4 minutes, recovery occurred at 41 +/- 9 minutes, and discharge occurred at 56 +/- 11 minutes. No vomiting or clinically significant oxygen desaturation (defined as a drop of > 4% or to < 91%) was observed. We conclude that intranasal midazolam is a safe and effective sedative for laceration repair under local anesthesia in preschool-aged children. We recommend a dose of 0.3 to 0.5 mg/kg, with treatment failure less likely after 0.4 to 0.5 mg/kg compared with less than 0.3 mg/kg.