Since Gibbs published “Cuspal Fracture Odontalgis” in 1954, a large number of researchers have presented papers on tooth fractures. However, most of them were concerned with teeth that had been treated with root canal fillings or restorations. I found that there was clenching, and that hairline fractures had arisen even in the intact vital teeth of patients that had not received any dental treatment and whose oral cavities had absolutely no caries or periodontal disease. I also noticed that the fracture lines followed the central grooves or fissures in the buccal and lingual surfaces. Therefore, in such cases it seems that the fractures arose solely as a result of so called “stress” or “occulusion” which is composed and affected by the gnathostomatic system. However, dental treatment would not be a causative factor here at all.
I studied a sample of 83 subjects who clenched their teeth. Group A was comprised of 14 subjects who actually had hairline fractures. Four of them refused to allow occlusal analysis involving diagnosis of the occlusion. Group B was comprised of 21 subjects who had no hairline fractures and no defects in the teeth, although they clenched their teeth. Group C was 48 subjects who clenched their teeth and had dental defects that seemed associated with this clenching.
Examination and analysis were carried out on the above 83 subjects. Standardized models were fabricated based on the HIP plane of three of the subjects from group A who had hairline fractures in teeth that had never received any dental treatment. In order to examine the condition of the mesiodistal and buccolingual contacts and the occlusion of the occluded maxillary and mandibular models, two sets of each model were cemented with adhesive cement after reference lines were scribed where sectioning was planned at the pits, fissures and cusp tips of the models. Following the lines where sectioning was planned, one of the models was sectioned mesiodistally, and the other buccolingually, and photographs were taken.
Based on the findings, the occlusal conditions were graphed, each physical characteristic of the structural elements of the teeth was incorporated, and finite element analysis was carried out. In addition, specimens were carefully taken from extracted impacted wisdom teeth, the wet compressive strength was determined, and investigations were also made as to how the fracture of the tooth structural elements would occur.
It became clear that the fracture line would run vertically along the central groove and fissures on the buccal and lingual surfaces. I would like to make it clear that the hairline fractures to which I am referring are limited to the above mentioned definition, and are fundamentally different from previously reported cuspal fractures, root fractures that occur in endodontically filled teeth, and traumatic fractures.
Based on the above fundamentals, I would like to report how to identify those patients who are likely to have the primary factors that might produce hairline fractures, and discuss prevention and treatment methods.

抄録全体を表示

 The 2011 off the Pacific coast of the Tohoku earthquake caused severe liquefaction events in the Kanto region, which is 300-400 km south of the earthquake's epicenter. All-core drillings and trenching surveys were carried out at Yodaura and Mukoya, which are situated in the lowland along the lower Tone River in the central Kanto region. The Yodaura site is on reclaimed land where a former lake was filled in by sand pumping from 1969 to 1974. The sediments at Yodaura consisted of silts and clays of the former Lake Yodaura deposits (natural sediments) and sandy strata composed of artificial fill. No evidence was found of liquefaction in the natural deposits, but the artificial-fill deposits suffered severe liquefaction. Three distinct sand dikes (yS1 sand dyke–yS3 sand dyke) cut the artificial strata at Yodaura: yS1 sand dyke, composed of gray, unoxidized sand, reached the ground surface and cut yS2 sand dyke, which was composed of light-brown, oxidized sand. Therefore, two liquefaction events occurred at the same point: the older event, which produced yS2 sand dyke, was probably induced by the 1987 off the east coast of Chiba Prefecture earthquake (Mj = 6.7), and the newer one, which produced yS1 sand dyke, was induced by the 2011 earthquake. The third sand dike (yS3 sand dyke) originated in a bed of fine to medium sand containing shell fragments in the artificial strata and contained fragments of asphalt from the ground surface. This dike is consistent with eyewitness accounts of sand gushing during the 2011 event. These accounts report that the ground pulsated at intervals of several seconds, and water and sand spouted from the ground simultaneously with each ground motion pulse. The presence at Yodaura of massive un-stratified sand beds within well-stratified sandy layers, especially near the sand dikes, indicates that liquefaction destroyed the original structure of the sediments. The Mukoya site is on reclaimed land where an abandoned channel of the Tone River was artificially filled in after 1956 by sand pumping and sediment dredging. The surface sediments at the Mukoya site are composed of Holocene floodplain deposits, abandoned channel sediments deposited between 1626 and 1956, and artificial strata. Two distinct deformation structures (mS1 and mS2) were observed in a trench wall. mS1 was a sand dyke that originated in the upper member of the abandoned channel sediments and reached the ground surface. The mS1 sand dyke consisted of liquefied materials derived from the dredged fine to medium sand deposits of the lower part of the artificial strata, and where it was ejected, a “shoulder-like” point formed on the upper surface of the sandy dredged deposits. Structure mS2 was a depression structure in the lower part of the artificial strata that displaced the sandy dredged deposits and an underlying buried soil layer downward. A “sill-like” horizontal sand dike extended from the sandy deposits into the buried soil. In the muddy upper part of the artificial strata, there were many fractures parallel to sand dyke mS1 and the “shoulder” of the sandy dredged deposits. The presence of these fractures indicates that minor subsurface geological structures affected the ground motion and location of liquefied sites caused by the earthquake.

抄録全体を表示

Wire-grid polarizing films have been used intensively as parts of the displays of liquid crystal TVs, liquid crystal projectors, and personal computers. Wire-grid polarizing films have metal wires and whose width is less than the wave length of light. The incident light having perpendicular polarization to the wire pass through the wire-grid polarizing films and the light of parallel polarization reflects, Since silver has the highest reflectance in metal, the efficiency of recycle use of reflected light on the Ag-WGPOLARIZER is expected to be the highest among other metals.
With a cyanide-free bath, we damascene electrodeposited silver into trenches 145 nm wide and 175 nm deep. The silver deposited on the film was then partly removed using ion milling and metal wires were fabricated. The reflectance of S-polarization is inversely related to the amount of voids in the trenches. Smaller current density and a larger amount of Na₂S₂O₃ decrease the amount of voids and hence increase the reflectance of S-polarization.

抄録全体を表示

For measuring the flow velocity of sheath region of an arc burning through a polyethylene tube (PE arc), we obseved the in-flight motion of non-vaporized bulky carbon particles which are ablated from the tube wall and emit strong continuum in the sheath region at the tube exit. The velocity was calculated from the time difference during which the particles passed through two slits located along the arc axis. The experimental parameters are arc current (DC 5 to 15A), tube inner diameter (2 and 4mm) and tube length (10 to 30mm).
The results show that the sheath flow velocity of PE arc increases with increasing arc current, decreases with increasing tube diameter and increases in proportion to tube length. The maximum value of the velocity is about 300m/s at 15A, 2mm in tube diameter and 30mm in tube length. Mass of the polyethylene tube was measured before and after arcing, and the mean velocity across the cross-section of the tube is roughly estimated from the mass difference assuming that the gas temperature is uniform inside the tube. The tendency of the estimated characteristics of flow velocity versus tube length agrees with the measured one. Also, it is deduced from the experimental results that the flow velocity inside the tube is proportional to axial distance from the tube center.

抄録全体を表示

断層破砕帯の変形メカニズムは地殻浅部の断層形成時の温度・圧力および変形速度などにより影響されるので, 断層破砕帯は断層形成時の変形環境を記録していると考えられる. したがって, 断層破砕帯の組織構造の解析によって, 断層活動史・古地震イベント・断層変位センスなどを推定することができる. 本論では, 五助橋断層・三峠断層などの例を挙げて, 活断層のト・土木工事の地質調査における基盤岩の断層破砕帯の組織構造の解析方法と適用法を述べるとともに, その問題点を指摘する.

抄録全体を表示

二観測点間のP波の相対走時を異なる周波数帯で測定する手法を開発した．この手法では観測点下の地殻多重反射波によって生じる分散効果が自動的に補正される．0.03Hzから0.77Hzの周波数帯の中で狭帯域の10帯域を設定し，地殻多重反射波補正したP波波形を他方の観測点の波形と波形相関をとることで相対走時を測定する．この手法をフ

ポリネシアおよび北西太平洋に設置された広帯域海底地震計のデータ，および周辺の陸上地震観測点のデータに適用した．得られたデータに有限波長理論に基づくインバージョンを適用することにより，これまで十分な解像度が得られなかった領域において高分解能のトモグラフィーモデルを得ることに成功している．

抄録全体を表示

パターン基板上の1回の有機金属気相成長法(MOCVD)あるいは分子線エピタキシャル法(MBE)による化合物半導体の選択成長により，複数の結晶成長面を組み合わせた三次元量子ナノ構造が自己組織的に形成される．この技術を応用して，回折格子を形成した基板上の1回の選択成長による利得結合分布帰還型(DFB)レーザーや，V溝量子細線上に光キャリア発生部と電荷検出部が一体化した高感度量子細線光電界効果トランジスタ(FET)を簡単な工程で製作した．

抄録全体を表示

Clenching during waking hours as well as grinding during sleep are known to be contributory factors to the perpetuotion of masticatory muscle pain.
Although studies have been conducted on nocturnal bruxism and daytime clenching in controlled laboratory settings, few reports have focused on the management of daytime clenching in natural environments with the utilization of biofeedback training. One of the reasons for the non-utilization of EMG biofeedback for patients exhibiting clenching behavior is that the biofeedback devices are too cumbersome to be carried around by the test subject. To expand the applicability of biofeedback training on a daily basis, the device should be small enough to be ignored by others.
This paper introduces a newly developed customized EMG recording device with two main components, namely the data-recording and auditory feedback portions. The dual-channel EMG recording system consists of on Ag-AgCl electrode pair unit and digital recorder with a 12-bit A/D converter. Hum filter of 50 Hz and band pass filter of 23-450 Hz are also equipped for EMG data collection. EMG activity is displayed on a small LCD on the surface of the device in root mean square values ranging from 0 to 1250μV. This unit permits continuous recording for 8 h 40 min at a data-sampling rate of 4Hz. An auditory feedback signal informs the user via a headset when EMG activity exceeds the arbitrarily defined threshold in each channel.
Since this EMG biofeedback device is easy to carry around, it should help to reduce daytime clenching behavior in natural environments.

抄録全体を表示

The counting of colloidal pitch by means of a haemocytometer is nowadays an accepted analytical method, but it is time consuming, it gives no information on size distribution of pitch particles, and the results depend on the person counting. A new analytical method has been developed at our laboratories in which the pitch is dyed with a fluorescent dye. The colloidal pitch is then separated from the fibres and passed through a capillary, and the individual particles are hydrodynamically focused. A laser beam passes through the stream of single particles and excites the dye. The intensity of the fluorescent light is proportional to the volume of each pitch particle, and the particle count per unit of time is a measure of the pitch concentration. A personal computer is used to count the particles and to analyse their size distribution.
This method is an excellent tool for evaluating the efficiency of pitch control aids. When a single cationic polymer was added, it was found that the decrease of the pitch count was a function both of the level of addition and the charge density (and other properties) of the polymer. When a combination of poly-electrolytes was added, both an increase and a decrease in the pitch count was observed, which depended on the polymer concentration, the concentration ratio, the order in which they were added, and the time elapsed between adding them. The polymers evaluated included polyethylenimines, poly-DADMAC, and dicyan-diamide resins. This method can easily be combined with measuring the zeta potential of pitch particles, which leads to a better understanding the mechanisms involved.

抄録全体を表示