Analysis of mid-infrared lasing in active random media.

Lasing behaviour of 2-dimensional active random structures, designed to work in the Mid-IR region, has been investigated at different input powers by varying the amount of scattering intensity. A Monte Carlo based simulation tool has been developed including a model to manage the optical amplification. The analysis of photon travel distance has been considered to show the random lasing behaviour with particular attention on lasing threshold at different scattering intensity. The simulated results are in agreement with experiments.

Modal analysis in 2D media with variable disorder.

Modal properties of 2D disordered optical structures have been numerically analyzed, in the Mid-IR region, varying the amount of scattering and the disorder level. The modal properties study has been carried out through the use of Finite Element Method, highlighting the localized regime transition and investigating the quality factor. The results have been interpreted in a statistical fashion, investigating light diffusion in these structures with the help of Monte Carlo Method. An alternative measure of randomness weight has been proposed to support the numerical results.

Ultraviolet random lasing action from highly disordered n-AlN/p-GaN heterojunction.

Room-temperature random lasing is achieved from an n-AlN/p-GaN heterojunction. The highly disordered n-AlN layer, which was deposited on p-GaN:Mg layer via radio frequency magnetron sputtering, acts as a scattering medium to sustain coherent optical feedback. The p-GaN:Mg layer grown on sapphire provides optical amplification to the scattered light propagating along the heterojunction. Hence, lasing peaks of line width less than 0.4 nm are emerged from the emission spectra at round 370 nm for the heterojunction under forward bias larger than 5.1 V. Lasing characteristics of the heterojunction are in agreement with the behavior of random lasers.

Electroluminescence from n-In2O3:Sn randomly assembled nanorods/p-SiC heterojunction.

Room-temperature electroluminescence (EL) has been realized from Sn-doped In(2)O(3) (In(2)O(3):Sn) nanorods. Heterojunction light-emitting diode (LED) was formed by depositing a layer of randomly packed n-In(2)O(3):Sn nanorods onto a p-type 4H-SiC substrate. It is found that the emission intensity of the heterojunction LED under forward bias can be maximized by doping the In(2)O(3) nanorods with 3 mol. % of Sn. Furthermore, two emission peaks of the EL spectra are observed at approximately 395 and approximately 440 nm. These ultraviolet and visible peaks are attributed to the radiative recombination at Sn induced and intrinsic defect states of the In(2)O(3):Sn nanorods.

Ultraviolet electroluminescence from randomly assembled n-SnO(2) nanowiresp-GaN:Mg heterojunction.

Electroluminescence characteristics of a heterojunction light-emitting diode, which was fabricated by depositing a layer of randomly assembled n-SnO(2) nanowires on p-GaN:Mg/sapphire substrate via vapor transport method, were investigated at room temperature. Peak wavelength emission at around 388 nm was observed for the diode under forward bias. This is mainly related to the radiative recombination of weakly bounded excitons at the shallow-trapped states of SnO(2) nanowires, Under reverse bias, near bandedge emission from the p-GaN:Mg/sapphire leads to the observation of emission peak at around 370 nm.

Edge-emitting ultraviolet n-ZnO:Al/i-ZnO/p-GaN heterojunction light-emitting diode with a rib waveguide.

An edge-emitting ultraviolet n-ZnO:Al/i-ZnO/p-GaN heterojunction light-emitting diode with a rib waveguide is fabricated by filtered cathodic vacuum arc technique at low deposition temperature (approximately 150 degrees C). Electroluminescence with emission peak at 387 nm is observed. Good correlation between electro- and photo- luminescence spectra suggests that the i-ZnO layer of the heterojunction supports radiative excitonic recombination. Furthermore, it is found that the emission intensity can be enhanced by approximately 5 times due to the presence of the rib waveguide. Only fundamental TE and TM polarizations are supported inside the rib waveguide and the intensity of TE polarization is approximately 2.2 time larger than that of TM polarization.

Evaluation of the use of buprenorphine for opioid withdrawal in an emergency department.

OBJECTIVES: To examine the use of buprenorphine for the treatment of opioid withdrawal (OW) in an emergency department (ED) setting. METHODS: The medical records of all adult patients who presented to the study ED during a 10 week period for OW were abstracted. Subjects were categorized as receiving buprenorphine, symptomatic treatment or no pharmacologic treatment for their OW. The three groups were compared by patient and service characteristics, withdrawal symptoms and outcomes. RESULTS: Of the 11,019 patients who presented to the ED during the 10 week study period, 158 (1.4%) were eligible. Subjects were more likely to receive buprenorphine (56%) compared to symptomatic treatment only (26%) or no pharmacologic treatment (18%). Subjects who received buprenorphine were more likely to have a history of suicide ideation (34% versus 12% p<0.05) compared to subjects who received symptomatic treatment(s) and were less likely to present with a gastrointestinal complaint (9% versus 25% p<0.05). Subjects who received buprenorphine were less likely to return to the same ED within 30 days for a drug-related visit (8%) compared to those who received symptomatic treatment (17%) (p<0.05). CONCLUSIONS: Buprenorphine was a common treatment for OW in this ED without any documented adverse outcomes. Given that it did not result in an increase in drug-related return ED visits and its proven efficacy in other settings, a prospective evaluation of its potential value to ED patients who present with OW is warranted.

Ultrasound in the evaluation and management of blunt abdominal trauma.

Failure to detect intraabdominal injury in the patient with blunt trauma may result in significant morbidity and mortality. The diagnosis of abdominal injury remains a clinical challenge. Presented here is a review of recent literature comparing ultrasound with diagnostic peritoneal lavage and computed tomography in the evaluation of blunt abdominal trauma.

Clinical evaluation of the poisoned patient and toxic syndromes.

Poisonings and toxic exposures are prominent causes of morbidity and mortality in patients that present to the emergency department. The American Association of Poison Control Centers, in its 1994 annual report, cites a 10% increase in the number of reported cases of poison exposure. The clinical evaluation and management of such patients remain challenging. Few specific antidotes are available for the many potential poisonings that occur annually. Rapid stabilization, resuscitation, and recognition of major toxic syndromes, along with appropriate utilization of laboratory testing, guide the clinician in the treatment of such patients.

Esophageal detector device versus detection of end-tidal carbon dioxide level in emergency intubation.

STUDY OBJECTIVES: To confirm the ability of the esophageal detector device (EDD) to indicate positioning of endotracheal tubes (ETTs) in patients intubated under emergency conditions and to compare the performance of the EDD with that of end-tidal carbon dioxide (ETCO2). METHODS: This single-subject study comprising a prospective case series was conducted in the emergency department of an urban university hospital. All adult patients were intubated either in the ED or by paramedics in the field. ETT position was initially evaluated by means of auscultation, then EDD, and, finally, spectrographic qualitative ETCO2 monitoring in each patient. Discrepancies between the EDD and ETCO2 results were resolved by means of direct laryngoscopy. RESULTS: In 100 intubated patients, both the EDD and ETCO2 monitoring detected the single esophageal intubation that occurred. Of the remaining 99 tracheal intubations, the EDD correctly indicated tracheal placement in 98 (sensitivity, 99%) and was indeterminate in 1 case because of blockage of the ETT by secretions resulting from pulmonary edema. By comparison, ETCO2 monitoring correctly indicated tracheal placement in 86 cases (sensitivity, 87%) and was incorrect in 13 cases (P < .01). ETCO2 monitoring failed in 2 patients with pulmonary edema and in 11 patients with cardiac arrest. Among the 37 patients in the cardiac arrest group, the EDD correctly indicated ETT placement in 37 patients (sensitivity, 100%). In contrast, ETCO2 monitoring correctly indicated ETT placement in 26 patients (sensitivity, 70%; P < .01). CONCLUSION: The EDD reliably confirms tracheal intubation in the emergency patient population. The EDD is more accurate than ETCO2 monitoring in the overall emergency patient population because of its greater accuracy in cardiac arrest patients. [Bozeman WP, Hexter D, Liang HK, Kelen GD: Esophageal detector device versus detection of end-tidal carbon dioxide level in emergency intubation.

[Detection of serum antibodies in rats infected with Angiostrongylus cantonensis by indirect fluorescent antibody test].

Frozen section specimens with a thickness of 4 microns were made from adult worms of Angiostrongylus cantonensis in order to detect the serum antibodies in rats infected with Angiostrongylus cantonensis by indirect fluorescent antibody test (IFAT). The results showed that the positive rates of the serum samples 2 and 4 weeks after infection were 92.0% (46/50) and 100%(19/19), respectively. The results of serum samples in healthy rats and normal saline (as control) were negative. This technique proved to have a highly detectable rate and the positive reaction might occur in early infection. It might be used for the early supplementary diagnosis of angiostrongyliasis.

[Experimental study on detection of serum antibodies by immunoenzyme staining using adult Angiostrongylus cantonensis frozen section].

This paper reported on the results of detection of serum antibodies in rats with Angiostrongylus cantonensis infection by immunoenzyme staining of adult frozen section. The positive rates of serum antibodies in rats 2 and 4 weeks after infection were 80% and 93.3%, respectively. The result of healthy control rats was negative.

Cerebral blood flow during normocapnic hyperoxia in the unanesthetized pony.

The effect of hyperoxia on cerebral blood flow (CBF) was examined in 12 unanesthetized ponies. CBF was determined using radioactive microspheres, 15 micrometer in diam, durijng inspriation of the following gases: 1) room air (control); 2) 40% I2 in N2; and 3) approximately 100% O2 with 2.2-4.5% CO2 added to maintain isocapnia. CBF did not change from control values during either level of hyperoxia. However, cerebrospinal fluid (CSF) carbon dioxide tension (PCO2) increased during 40% O2 (delta 1.0 Torr) and approximately 100% O2 (delta 2.9 Torr). This rise in CSF PCO2, not due to a change in CBF, may have resulted from a decrease in the CO2 carrying capacity of cerebral venous blood during hyperoxia (Haldane effect). Although respiration did not change during 40% O2, expired minute volume increased 25% during approximately 100% O2 due to an increase in tidal volume. This rise in respiration was not associated with changes in any of the conventional stimuli to breathing (arterial pH, O2 tension, or PCO2 or CSF pH). One possible explanation was that cerebral extracellular fluid pH, in the vicinity of the central chemoreceptors, or cerebral intracellular fluid pH changed in a direction unlike CSF pH. An alternate explanation was that the CO2 in the inspired gas activated CO2-sensitive receptors in the lungs.