Percutaneous vertebroplasty (PVP) is an efficient procedure to treat pain due to osteoporotic vertebral compression fractures (OVCFs). However, some patient populations experience recurrent vertebral fracture after initial successful procedure. There are a lot of literatures about the effectiveness of this procedure but few concerning the development of recurrent, new compression fracture. This is a retrospective review of all PVPs performed in author's institution from September 1999 to December 2001 to investigate the factors related to the development of new symptomatic OVCFs after PVPs. A retrospective review of 244 cases of PVP for symptomatic OVCFs at 382 levels was performed. Sociodemographic, clinical, radiologic, and procedural data were analyzed and compared between the two patient groups (control group : no further symptomatic OVCFs after the initial PVP, "new symptomatic fracture" group: with newly developed symptomatic OVCF). Statistical analysis was performed between the variables of the two groups. Survival analysis was performed using the Kaplan-Meier method. Over all, 38 among 244 treated patients (15.6%) had experienced newly developed symptomatic OVCF(s) during the follow up period (mean 52.5 months). Old age and the presence of multiple treated vertebrae at the initial PVP were assessed as a strong parameter for predicting new symptomatic OVCF. With increasing preoperative wedging deformity the risk of developing new symptomatic OVCF decreased. The Kaplan-Meier estimate of the 1 year fracture-free rate was 92.2%. The Kaplan-Meier curve showed that 7.8% of the patients would experience new symptomatic OVCF within 1 year after initial PVP. A preoperative only mild wedge deformity of the fractured vertebra(e) could indicate the increased risk of developing new symptomatic OVCF after vertebroplasty.

The mentalis muscle (MT) is the only elevator of the lower lip and the chin, and it provides the major vertical support for the lower lip. However, there are few reports on the relationship between the MT and its surrounding muscles. The aim of this study was to clarify the morphology of the MT, especially in relation to the orbicularis oris muscle and the incisivus labii inferioris muscle (ILI), thereby providing data to understand the function of the MT in relation to the surrounding muscles. The MT was examined in 40 specimens of embalmed adult Korean cadavers. The medial fibers of both MTs descended anteromedially and crossed together, forming a dome-shaped chin prominence in all specimens. The lateral fibers of the MT descended inferomedially in 38 specimens (95%) and inferolaterally in 2 specimens (5%). The upper fibers of the MT were short and ran horizontally, whereas the lower fibers were long and descended inferomedially or vertically. The upper fibers of the MT were intermingled with the inferior margin of the orbicularis oris muscle in all specimens. The originating muscle fibers of the ILI were intermingled with the upper lateral MT in all specimens. Some of the ILI fibers extended inferomedially to the middle or lower portion of the MT in 22 specimens (55%). The results of this study constitute new anatomical knowledge regarding the MT and will be useful to surgeons performing various surgical procedures of the chin area.

The aim of this study was to demonstrate the morphology of the quadratus plantae (QP) in relation to the tendinous slips of the flexor hallucis longus (FHL) and their surrounding structures, thereby providing data to understand function of the QP during gait, and for analyzing the movements of the foot and designing postoperative rehabilitation programs. The QP was investigated in 50 specimens of embalmed adult cadavers. The QP inserted into the tendon of the flexor digitorum longus (FDL) and the tendinous slips of the FHL in 96%, and only to the tendon of the FDL in 4%. The tendinous slip of the FHL targeted the tendon for the second toe in 4 of the 50 specimens (8%). The tendinous slip divided into two separate slips to the tendons for the second and third toes in 32 specimens (64%), and for the second, third, and fourth toes in 14 specimens (28%). Thus, the tendon and tendinous slips of the FHL may distribute the load of the great toe to the second toe to the third or fourth toe in the forefoot, especially during toe-off. In addition, the main attachment of the QP to the tendinous slips of the FHL may provide more efficient control of the long flexor tendons in comparison with that of the QP to the tendon of the FDL.

The aim of this study was to clarify the morphologic and spatial relationships of the inferior bundle of the buccinator and the incisivus labii inferioris muscle (ILI) and their surrounding structures. The inferior bundle of the buccinator and the ILI were investigated in 40 hemifaces from Korean cadavers. The inferior bundle (or fourth band) of the buccinator muscle was observed in 14 (35%) of the 40 specimen sides. The ILI was found in 39 (97.5%) of the 40 specimen sides. The spatial relationships of the ILI with the buccinator muscle and the orbicularis oris muscle were classified into 4 categories based on the existence of the inferior bundle of the buccinator. These observations indicate that the lower portion of the buccinator including the third and fourth inferior bundles and the ILI could affect the alveolar bone of the mandible or occlusion during these muscular movements.

An AlGaN / GaN wide band-gap semiconductor with the Ta/ Ti/ Al/ Ni/ Au ohmic contact ͑7.5 ϫ 10 −7 ⍀ cm 2 ͒ was demonstrated by 700°C annealing for 1 min. High-resolution electron microscopy and synchrotron-radiation x-ray diffraction showed that nitride phases were formed at the interface between the metal and the AlGaN layer. The thick formation of TaN / TiN interfacial layers appears to be responsible for the good ohmic contact behavior in Ta/ Ti/ Al/ Ni/ Au metal scheme. The surface morphology of Ta-based contacts is superior to that of the Ti/ Al/ Ni/ Au metal scheme. The fabricated heterostructure field-effect transistor exhibited the saturation drain current density of 605 mA/ mm and transconductance of 246 mS/ mm.The GaN wide band-gap semiconductors have desirable material properties including a large band gap, low value of the dielectric constant, high thermal conductivity, and high critical-electric field for breakdown. Especially, the AlGaN / GaN heterostructure has been demonstrated to produce a two-dimensional electron gas ͑2DEG͒ that has high sheet-charge density on the order of 10 13 cm −2 , excellent saturation velocity of about 2 ϫ 10 7 V / cm, and roomtemperature mobility in the range of 1000-1500 cm 2 /V s. These make possible attracting devices for high-temperature, high-frequency, and high-power applications. [1][2][3][4] Ohmic-contact resistances should be reduced as low as possible to obtain high-efficiency performance of devices. 5-10 For GaN electronic and optical devices, Lin et al. first reported the Ti/ Al metal scheme. 5 Fan et al. obtained a 10 −7 ⍀ cm 2 level of contact resistivity with the Ti/ Al/ Ni/ Au metal scheme. 6 Ti/ Al metallization with hightemperature annealing ͑Ͼ800°C͒ has also been used as the standard ohmic contact on AlGaN / GaN heterostructure field-effect transistors ͑HFETs͒ in order to achieve low contact resistivity ͑Ͻ10 −5 ⍀ cm 2 ͒. 8-10 Liu et al. first reported that the Ti/ Al metal scheme on AlGaN / GaN showed contact resistivity of 3.2ϫ 10 −6 ⍀ cm 2 with 950°C heat treatment. 11 Qiao et al. recently reported that the addition of a Ta layer below the Ti/ Al metal layer leads to contact resistivity as low 5 ϫ 10 −7 ⍀ cm 2 at the 950°C annealing temperature. 12,13 Because high-temperature annealing has some drawbacks, such as surface roughness, it is necessary to develop new methods which reduce contact resistivity at moderate annealing temperatures. Many attempts have been made to find a way of lowering the contact resistivity and improving the surface characteristics. Recent results have shown that the additional layers on the Ti/ Al metal scheme ͑Ni/ Au, Pt/ Au, and Ti/ Au͒ reduce the contact resistivity at moderate-temperature annealing. The reported contact resistivity is 2.8ϫ 10 −6 ⍀ cm 2 with 700°C heat treatment for Ti/ Al/ Ni/ Au, 5.3ϫ 10 −6 ⍀ cm 2 with 800°C heat treatment for Ti/ Al/ Ti/ Au, and 4.7ϫ 10 −7 ⍀ cm 2 with 850°C heat treatment for Ti/ Al/ Mo/ Au. [14][15][16][17] The tunneling effect due to nitride formation at the AlGaN interface is genera...