Graded-index thin-film stack for cladding and coupling.

A graded-index multilayer thin-film stack is optimized to act as a cladding layer on top of a silicon (Si) nanowaveguide and also a collimator for chip coupling where the waveguide ends. The numerical example shows an optimized graded-index profile from 2.35 to 1.45 provides an optical coupling to the standard single-mode fiber with efficiency close to 90% while retaining tight light confinement for the Si nanowaveguide. The corresponding material realization of a graded-index profile with a Si-rich nitride SiNx/SiON/SiO2 system is explored using inductively coupled plasma chemical vapor deposition, and a SiNx cladded Si waveguide is demonstrated.

Heterogeneously integrated III-V laser on thin SOI with compact optical vertical interconnect access.

A new heterogeneously integrated III-V/Si laser structure is reported in this report that consists of a III-V ridge waveguide gain section on silicon, III-V/Si optical vertical interconnect accesses (VIAs), and silicon-on-insulator (SOI) nanophotonic waveguide sections. The III-V semiconductor layers are introduced on top of the 300-nm-thick SOI layer through low temperature, plasma-assisted direct wafer-bonding and etched to form a III-V ridge waveguide on silicon as the gain section. The optical VIA is formed by tapering the III-V and the beneath SOI in the same direction with a length of 50 µm for efficient coupling of light down to the 600 nm wide silicon nanophotonic waveguide or vice versa. Fabrication details and specification characterizations of this heterogeneous III-V/Si Fabry-Perot (FP) laser are given. The fabricated FP laser shows a continuous-wave lasing with a threshold current of 65 mA at room temperature, and the slope efficiency from single facet is 144 mW/A. The maximal single facet emitting power is about 4.5 mW at a current of 100 mA, and the side-mode suppression ratio is ∼30 dB. This new heterogeneously integrated III-V/Si laser structure demonstrated enables more complex laser configuration with a sub-system on-chip for various applications.

Demonstration of heterogeneous III-V/Si integration with a compact optical vertical interconnect access.

Heterogeneous III-V/Si integration with a compact optical vertical interconnect access is fabricated and the light coupling efficiency between the III-V/Si waveguide and the silicon nanophotonic waveguide is characterized. The III-V semiconductor material is directly bonded to the silicon-on-insulator (SOI) substrate and etched to form the III-V/Si waveguide for a higher light confinement in the active region. The compact optical vertical interconnect access is formed through tapering a III-V and an SOI layer in the same direction. The measured III-V/Si waveguide has a light coupling efficiency above ~90% to the silicon photonic layer with the tapering structure. This heterogeneous and light coupling structure can provide an efficient platform for photonic systems on chip, including passive and active devices.

Exploring High Refractive Index Silicon-Rich Nitride Films by Low-Temperature Inductively Coupled Plasma Chemical Vapor Deposition and Applications for Integrated Waveguides.

Silicon-rich nitride films are developed and explored using an inductively coupled plasma chemical vapor deposition system at low temperature of 250 °C with an ammonia-free gas chemistry. The refractive index of the developed silicon-rich nitride films can increase from 2.2 to 3.08 at 1550 nm wavelength while retaining a near-zero extinction coefficient when the amount of silane increases. Energy dispersive spectrum analysis gives the silicon to nitrogen ratio in the films. Atomic force microscopy shows a very smooth surface, with a surface roughness root-mean-square of 0.27 nm over a 3 µm × 3 µm area of the 300 nm thick film with a refractive index of 3.08. As an application example, the 300 nm thick silicon-rich nitride film is then patterned by electron beam lithography and etched using inductively coupled plasma system to form thin-film micro/nano waveguides, and the waveguide loss is characterized.

Efficacy of ventilator-associated pneumonia care bundle for prevention of ventilator-associated pneumonia in the surgical intensive care units of a medical center.

BACKGROUND: Ventilator-associated pneumonia (VAP) is one of the most serious treatment-related infections resulting in high mortalities and costs. Our hospital has implemented bundle care in the intensive care units (ICUs) with special focus on VAP prevention. This is a retrospective study to evaluate its efficacy. METHODS: We implemented a six-item VAP care bundle modified from that of the Institute for Healthcare Improvement at five surgical ICUs (SICUs) in the National Taiwan University Hospital. A multidisciplinary teamwork was involved in this bundle care. This study analyses the SICU utilization, ventilator utilization, and VAP incidence between January 2006 and March 2013 to assess the impact of VAP bundle in a clinical setting. RESULTS: A total of 28,454 SICU patients were analyzed in this study and patients under the age of 18 were excluded (n = 1329); eventually, 27,125 patients were enrolled, with 12,913 patients from the pre-VAP bundle phase and 14,212 from the post-VAP bundle phase. Patients from the post-VAP phase tended to be older (p = 0.024) and with shorter SICU stay (p = 0.006), and disease severity scores (Therapeutic Intervention Scoring System, Glasgow Coma Scale, and Acute Physiology and Chronic Health Evaluation II score) were lower in the post-VAP bundle phase (p < 0.001), except the Injury Severity Score (p = 0.729). In response to VAP bundle interventions, no difference in SICU utilization (p = 0.982) between the pre-VAP and post-VAP bundle phases was noted, whereas the ventilator utilization was significantly decreased, from 1148.5 ventilator days to 956.1 ventilator days (p < 0.001) monthly; the VAP density had remarkably decreased from 3.3 to 1.4 cases per 1000 ventilator days (p < 0.001). CONCLUSION: Implementation of VAP bundle care decreases the incidence of VAP at SICU. Multidisciplinary teamwork, education, and a comprehensive checklist to improve health-care workers' compliance are the keys to success.

Early weightbearing and ankle mobilization after open repair of acute midsubstance tears of the achilles tendon.

PURPOSE: To study the effects of early weightbearing and ankle mobilization after acute repair of ruptured Achilles tendon. STUDY DESIGN: Comparative longitudinal study. METHODS: Patients in group 1 were postoperatively immobilized with their ankle in gravity equinus, they were encouraged to bear weight on the operated limb as soon as possible to full weightbearing, and they received a single cast change at 2 weeks, with the ankle accommodated in an anterior splint in a plantigrade position, allowing the ankle to be plantar flexed fully but not dorsiflexed above neutral. Patients in group 2 were immobilized with their ankle in full equinus with a cast change at 2 weeks, when the ankle was immobilized in mid equinus, and at 4 weeks, when the ankle was immobilized in a plantigrade position, and they were advised to bear weight. RESULTS: Patients in group 1 attended fewer outpatient visits, completely discarded their crutches at an average of 2.5 weeks, and more were satisfied with the results of surgery. At ultrasonography, the average thickness of the repaired tendon was 12.1 mm, with no difference in the thickness of the ruptured tendon regardless of postoperative management. There was no significant difference in isometric strength between the two groups. CONCLUSIONS: Early weightbearing with the ankle plantigrade is not detrimental to the outcome of repair after acute rupture of the Achilles tendon and shortens the time needed for rehabilitation. However, strength deficit and muscle atrophy are not prevented.

Long-term ultrasonographic features of the Achilles tendon after rupture.

PURPOSE: To assess the long-term ultrasonographic appearance of rupture of the Achilles tendon. SUBJECTS AND METHODS: We examined 70 patients at an average of 63 months (range 10-120 months) after rupture of the Achilles tendon. We assessed the patient's contralateral tendon and also performed ultrasonography on the Achilles tendon of 70 age- and sex-matched controls. We recorded the maximum transverse anteroposterior diameter, the presence of intratendinous alterations, and the presence of intratendinous calcification. RESULTS: The average maximum anteroposterior diameter of the ruptured tendon was 11.7 mm (SD = 2.10). The patients' normal tendons measured an average of 5.4 mm (SD = 0.9), and there was an average measure of 4.9 mm (SD = 0.5) (p = 0.0001) in the controls. There was no difference in the maximum anteroposterior diameter of the ruptured tendon depending on the method of treatment (conservative, open repair, percutaneous repair). Seventeen patients exhibited areas of hypoechogenicity in their ruptured tendon, two patients had areas of hypoechogenicity in their unruptured contralateral tendon, and 10 patients had calcification in their ruptured tendon. CONCLUSION: The anteroposterior diameter of the ruptured tendon was significantly greater than the nonruptured contralateral. However, when compared with a group of individually age- and sex-matched controls, the patients' contralateral tendons had significantly greater maximum anteroposterior diameter and had a greater prevalence of intratendinous alterations. This difference may represent a background of subclinical tendinopathy that may predispose to rupture.