Neural mechanism underlying self-controlled feedback on motor skill learning.

The present study investigated the neural mechanisms of self-controlled (SC) feedback underlying its learning advantages. Forty-two participants, including 24 females (16.43 ±â€¯2.61 years) and 18 males (17.56 ±â€¯0.86 years), were randomly assigned to a SC or yoked (YK) group. The 6-key-pressing task with a goal movement time was adopted as the experimental task. The behavioral results showed that the SC group demonstrated superior performance in transfer; however, the differences in retention did not reach statistical significance. Event-related potential analyses revealed that the SC group exhibited larger post-stimulus and post-feedback P3 amplitudes than the YK group in the frontal regions; these amplitudes were larger in the YK group in the parietal regions. The post-response error positivity amplitude was found to be larger in the YK group than in the SC group. These results suggest that SC feedback may allow the learner to more actively process the task stimuli and feedback information, and contributes to enhancing the learner's motivation and attachment to the task being practiced. The present study provides a neurophysiological explanation for why SC feedback is effective in learning a new motor skill.

Optimization of tungsten dual poly-metal gates in memory devices with Ti/Wn/WSiN barrier metal.

Due to the demand of high-speed/high-density and low power application of memory devices, tungsten dual poly gate (W-DPG; W/barrier metals/n+ and p+ poly-Si) electrode could be a good solution in order to reduce gate sheet resistance (Rs). Process optimization is completed for a diffusion barrier metal in a W-DPG. A new noble WSiN layer is inserted between the Ti/WN barrier metal and the tungsten gate electrode to maintain large grain size of W deposited by physical vapor deposition. The annealed WSiN during post-processing changes into crystallized WSi(x) mixed with SiN, which can make vertical conductive path between top and bottom interface, contributing to low vertical contact resistance (Rc) and low gate Rs adequate for high speed requirement of memory device. The Ti/WN/WSiN barrier is found to have the same electrical performance, ring oscillator singal delay as complicated multi-layes barrier metal, Ti/WN/TiN/WSi(x)/WN reported earlier. Therefore, the gate stack can be optimized by introducing a simpler diffusion barrier metal.

Evaluation of workers exposed to ethylene glycol monomethyl ether and ethylene glycol monomethyl ether acetate.

OBJECTIVES: Ethylene glycol monomethyl ether (EGME) and ethylene glycol monomethyl ether acetate (EGMEA) are widely used in industries as solvents for coatings, paint and ink, but exposure data are limited because they are minor components out of mixed solvents, as well as because of inconsistency in desorption solvent use. The objective of this study was to investigate the worker exposure profile of EGME and EGMEA. METHODS: Our study investigated 27 workplaces from June to September 2008 and detected EGME and EGMEA in 20 and 13, respectively. Both personal and area sampling were conducted using a charcoal tube to collect EGME and EGMEA. Gas chromatography with a flame ionization detector was used to analyze these compounds after desorption using a mixture of methylene chloride and methanol. RESULTS: The arithmetic mean concentrations of EGME and EGMEA during periods of full work shifts were 2.59 ppm and 0.33 ppm, respectively. The exposure levels were lower than the Korean Ministry of Labor (MOL) OEL (5 ppm) but higher than the ACGIH TLV (0.1 ppm). CONCLUSIONS: In general, the working environments were poor and required much improvement, including the use of personal protective equipment. Only 50% of the workplaces had local exhaust ventilation systems in operation. The average capture velocity of the operating local exhaust ventilation systems was 0.27 m/s, which did not meet the legal requirement of 0.5 m/s. Educating workers to clearly understand the handling and use of hazardous chemicals and improving working conditions are strongly suggested.

Osteonecrosis of femoral head treated with alendronate in a 14-year-old boy: a case report.

We describe a 14-year-old adolescent with osteonecrosis of femoral head, who was treated successfully with oral bisphosphonate. To prevent physeal damage by surgical treatment, alendronate was administered weekly for 20 months. A complete resolution was achieved. This report suggests that bisphosphonate may be an effective nonoperative treatment for osteonecrosis of femoral head.

Hemicallotasis for correction of varus deformity of the proximal tibia using a unilateral external fixator.

BACKGROUND: Gradual correction of varus deformity of the proximal tibia is generally accepted and produces good results. However, most studies have used circular external fixators, which are complex and cause patient discomfort. This study was undertaken to determine the efficacy of hemicallotasis with a unilateral external fixator for correction of varus deformity of the proximal tibia. METHODS: Thirteen patients (21 legs, 8 bilateral) were included in this study: 6 with constitutional bowing, 3 with a malunion, 2 with Blount's disease, and 2 with Turner syndrome. There were 7 males and 6 females of mean age 21 years (range 13-40). With an oblique osteotomy on the proximal tibia, a unilateral external fixator was placed on the medial side. Using a distraction of 1 mm/day, the external fixator was removed after consolidation of the callus. RESULTS: Surgery corrected medial proximal tibia angle from a preoperative average of 75.1° (64°-81°) to 88.6° (86°-90°) at final follow-up. Average tibiofemoral angle improved from -7° to 6.8°. The duration of external fixation averaged 101.3 days and the external fixation index was 70 days/cm. No patient had a limited ambulation, and all recovered preoperative range of knee motion (mean 130.1°) at final follow-up. Seven minor complications (pin tract infection, clamp loosening) and 1 major complication (uncorrected genu procurvatum) were observed. CONCLUSIONS: Hemicallotasis using a unilateral external fixator was found to be a safe and simple corrective procedure for varus deformity of the proximal tibia, with few complications.

A biomechanical analysis of locking plate fixation with minimally invasive plate osteosynthesis in a subtrochanteric fracture model.

OBJECTIVE: The objective of this study was to establish the relative fixation strengths of a locking plate, a dynamic condylar screw (DCS) plate, and a long proximal femoral nail (PFN). METHODS: The study involved three groups of composite large femoral synthetic bones of five specimens per group; plating using a locking compression plate-distal femur (LCP-DF), plating using a DCS plate, and nailing using a long PFN. A gap osteotomy model was used to simulate a comminuted subtrochanteric femur fracture. For each femur, a minimal preload of 100 N was applied before loading to failure. A vertical load was applied at 10 mm/min until femur failure. Load to failure, mode of failure, and displacement at load to failure were documented. RESULTS: Fixation strength (load or moment to failure) of LCP-DF (1,330 N; range, 1,217-1,460 N) was 26.6% and was greater in axial loading compared with DCS (1050.5 N; range, 956.4-1194.5 N) and 250% less in axial loading compared with long PFN (3633.1 N; range, 3337.2-4020.4 N; p=0.002). Ultimate displacement in axial loading was similar for LCP-DF (18.4 mm; standard deviation [SD], 1.44), DCS (18.3 mm; SD, 3.25), and long PFN (16.7 mm; SD, 1.82). CONCLUSIONS: The LCP-DF construct proved stronger than the DCS in terms of ultimate strength by biomechanical testing of a simulated subtrochanteric femur fracture with comminution. Although the nail construct proved strongest, the biomechanical performance of the locking plate construct may lend credence to the use of a locking plate versus the DCS plate for minimally invasive plate osteosynthesis of subtrochanteric femur fractures, which may be technically difficult to fix using a nail.