Research on the Force-Sensitive Characteristic of InAs QD Embedded in HEMT.

A force-sensitive structure of an InAs Quantum Dot (QD) embedded in a high electron mobility transistor (HEMT) is presented in this paper. The size of an InAs QD is about 30 nm prepared by the S-K growth mode, and the force-sensitive structure is fabricated by molecular beam epitaxy (MBE). The force-sensitivity characteristic of the QD HEMT is studied by the electrical and mechanical properties. The electrical characteristics show that the InAs QD-HEMT has linear, cut-off, and saturation operating states, and produces different output currents under different gate voltages, which shows that the structure is reasonable. Furthermore, the results of the output characteristics under different pressure show that the output voltage of the QD-HEMT decreases with the increase in pressure, which indicates that the InAs QD-HEMT has a vital mechanical-electrical coupling characteristic. The output voltage of the InAs QD-HEMT in the range of 0-100 kPa shows that the sensitivity was 1.09 mV/kPa.

Design of a TDOA location engine and development of a location system based on chirp spread spectrum.

Location based services (LBS) provided by wireless sensor networks have garnered a great deal of attention from researchers and developers in recent years. Chirp spread spectrum (CSS) signaling formatting with time difference of arrival (TDOA) ranging technology is an effective LBS technique in regards to positioning accuracy, cost, and power consumption. The design and implementation of the location engine and location management based on TDOA location algorithms were the focus of this study; as the core of the system, the location engine was designed as a series of location algorithms and smoothing algorithms. To enhance the location accuracy, a Kalman filter algorithm and moving weighted average technique were respectively applied to smooth the TDOA range measurements and location results, which are calculated by the cooperation of a Kalman TDOA algorithm and a Taylor TDOA algorithm. The location management server, the information center of the system, was designed with Data Server and Mclient. To evaluate the performance of the location algorithms and the stability of the system software, we used a Nanotron nanoLOC Development Kit 3.0 to conduct indoor and outdoor location experiments. The results indicated that the location system runs stably with high accuracy at absolute error below 0.6 m.

Evaluation of entire gastric fundic and esophageal varices secondary to posthepatitic cirrhosis: portal venography using 64-row MDCT.

BACKGROUND: There are no reports regarding entire gastric fundic and esophageal varices evaluated with 64-row multidetector CT (MDCT). We attempt to clarify the feasibility of portal venography with this scanner in evaluation of these varices. METHODS: A total of 33 patients, with clinically confirmed gastric fundic and esophageal varices secondary to posthepatitic cirrhosis, underwent thoracicoabdominal triphasic enhancement scans using 64-row MDCT along with conventional angiographic portography. CT portography and conventional portography were compared by statistical agreement to determine whether CT maximum intensity projection (CT-MIP) portography is useful in evaluation of entire gastric fundic and esophageal varices. RESULTS: CT-MIP portography demonstrated gastric fundic and esophageal varices, and the inflowing and outflowing vessels of the varices. Gastric fundic varices were shown in 32 cases (97.0%), and esophageal varices were in 27 (81.8%). The inflowing vessels including the left gastric vein and posterior gastric vein/short gastric vein were illustrated in 31 (94.0%) and 17 (51.5%) cases, respectively. The outflowing vessels including the azygos vein, hemiazygos vein, and gastro-renal shunts were seen in 30 (90.9%), 8 (24.2%), and 12 (36.4%) cases, respectively. Findings of CT-MIP portography and conventional angiographic portography were in close agreement (Kappa value ranged from 0.621 to 1.000). CONCLUSION: CT-MIP venography with 64-row MDCT could be considered as a method for detecting entire gastric fundic and esophageal varices developed from posthepatitic cirrhosis.

Evaluation of gastric fundic and oesophageal varices by 64-row multidetector computed tomography before and after transjugular intrahepatic portosystemic shunt with concurrent left gastric vein embolization.

OBJECTIVE: To determine the utility of 64-row multidetector computed tomography (MDCT) in assessing the changes of gastric fundic and oesophageal varices before and after transjugular intrahepatic portosystemic shunt (TIPS) with concurrent left gastric vein embolization. METHODS: Twenty-eight consecutive patients with gastric fundic and oesophageal varices resulted from posthepatitic cirrhosis, clinically confirmed with endoscopy, were enrolled into our study. All the patients underwent thoracicoabdominal triphasic enhancement scans with 64-row MDCT 2 weeks before TIPS along with embolizing left gastric vein, and 6 months after the therapy. Before and after the therapy, the varices shown on multiplanar reconstruction (MPR) were compared by Fisher's exact test to evaluate the changes. RESULTS: Gastric fundic and oesophageal varices were shown in 26 patients (92.9%) and 25 (89.3%) on MPR before the therapy, respectively. After the therapy, these varices diminished markedly, and were illustrated in six (21.4%) and 10 patients (35.7%), respectively (all P<0.05). As for the main inflowing vessel of the varices (left gastric vein), it was illustrated in 28 patients (100.0%) on preoperative CT-MPR. After the embolization, the left gastric vein had been completely occluded on postoperative CT-MPR. CONCLUSION: Significant eradication of gastric fundic and oesophageal varices on follow-up CT-MPR portography can be considered to assess the changes of gastric fundic and oesophageal varices before and after TIPS with concurrent left gastric vein embolization, and 64-row MDCT can be an effective modality to evaluate the changes.

[Clinical value of 64-slice CT angiography in detecting coronary artery anomalies].

OBJECTIVE: To determine the clinical value of 64-slice computed tomography angiography (CTA) in the diagnosis of coronary artery anomalies. METHODS: The coronary artery imaging data of 852 patients who underwent 64-slice CTA from July 2006 to May 2007 were retrieved. The imaging features of coronary artery anomalies confirmed by selective coronary angiography were reviewed. RESULTS: Eight (0.9%) coronary artery anomalies were found in the patients, which included 3 cases of anomalous aortic origin of coronary arteries, 3 cases of anomalous origin of the left main coronary artery from pulmonary artery, 1 case of coronary fistula from the right coronary artery to right atrium, and 1 case of coronary aneurysm. CONCLUSION: The 64-slice CTA can detect coronary anomalies and delineate the anatomic relationships among the peripheral structures, which can be considered as an early screening for coronary anomalies.