Shear Softening in a Metallic Glass: First-Principles Local-Stress Analysis.

Metallic glasses deform elastically under stress. However, the atomic-level origin of elastic properties of metallic glasses remain unclear. In this Letter using ab initio molecular dynamics simulations of the Cu_{50}Zr_{50} metallic glass under shear strain, we show that the heterogeneous stress relaxation results in the increased charge transfer from Zr to Cu atoms, enhancing the softening of the shear modulus. Changes in compositional short-range order and atomic position shifts due to the nonaffine deformation are discussed. It is shown that the Zr subsystem exhibits a stiff behavior, whereas the displacements of Cu atoms from their initial positions, induced by the strain, provide the stress drop and softening.

Microrelief suppresses large wrinkling appearance: an in silico study.

BACKGROUND AND PURPOSE: Extensive skin wrinkling during facial expressions is one of the considerable problems in aesthetic dermatology. Although a few in silico studies have been performed with the aim of revealing the mechanism of a wrinkled appearance, there have been few studies that take into account the influence of skin roughness (i.e. microrelief), which exists on human skin in vivo. In this study, finite element simulations were performed using multilayer skin models with microrelief to investigate how extensive wrinkling appears on human skin, especially focusing on the role of surface roughness in the wrinkling mechanism. METHODS: Linear and post-buckling analyses were performed on soft elastic laminate models using the finite element method. A simplified multilayer model of human skin was employed to examine the contribution of skin's multilayer structure to the large-wrinkle mechanism. Microrelief was included in the model to assess its effect on the mechanism. RESULTS: A large wrinkle was observed as dermal buckling following a number of buckling events on the stratum corneum. The existence of microrelief had an effect on the suppression of dermal buckling. CONCLUSION: Skin's multilayer structure should play a major role in the appearance of large wrinkles on human skin via its post-buckling behavior. This study suggested that fine microrelief on the skin surface hampers large wrinkles. These findings should be valuable for the development of cosmetic or medical treatments to prevent unfavorable skin deformations.

Ideal shear strength under compression and tension in C, Si, Ge, and cubic SiC: an ab initio density functional theory study.

Ideal shear strength under superimposed normal stress of cubic covalent crystals (C, Si, Ge, and SiC) is evaluated by ab initio density functional theory calculation. Shear directions in [112] and [110] on the (111) plane are examined. The critical shear stress along the former direction is lower than that along the latter in all the crystals unless the hydrostatic tension is extremely high. In both the [112]-shear and [110]-shear, critical shear stress is increased by compression in C but is decreased in the other crystals. The different response of the critical shear stress to normal stress is due to the strength of the bond-order term, i.e., dependence of the short-range interatomic attraction on the bond-angle.

Sleep-wake rhythm during stay in an intensive care unit: a week's long-term recording of skin potentials.

To monitor the sleep-wake cycle of patients during their stay in the intensive care unit (ICU), we tried continuous and long-term recording of skin potential (SP) levels in patients after surgery. A graph of the week-long SP showed the sleep-wake pattern to be evident until the fourth day. It disappeared beginning on the fifth day, resulting finally in delirium with a relatively high mean SP level. In another record, the administration of sedative agents to calm the excitement lowered the mean SP level and suppressed SP responses evoked by frequent day and night treatment or nursing care. Continuous monitoring of arousal level by SP will be of help in prevention of ICU syndrome.

Continuous recordings of skin conductance change during sleep.

Using a new compact and stable device, skin conductance change (SCC) was measured in five female undergraduates during sleep. The SCC trends and waveforms were almost identical to those of simultaneously recorded skin potential activity (SPA). A gradual increase in sympathetic sweating during sleep was also observed using SCC. However, the confounding effects of a burst of positive skin potential responses usually seen in SPA were absent using SCC.

Aberrant judgmental pattern of schizophrenic patients in weight discrimination.

Sixteen chronic schizophrenics and 16 normal controls were tested on a weight discrimination task in various categories and hand conditions. Schizophrenics made significantly more errors than normals when the 'equal' category was included, whereas schizophrenics' performance could approximate the normals' discriminations when the 'equal' category was excluded. In the former condition, the more inaccurate performance of schizophrenics was ascribed to the selective increase in the errors by the 'equal' judgments, which was not due to an increase in 'doubtful' judgments. These findings were assumed to reflect schizophrenics' preference to equal judgments, which seemed to be their fundamental cognitive attitude, because the same tendency was found on the various discrimination tasks of other sensory modalities. Furthermore, the present results supported neither left hemisphere dysfunction nor interhemispheric transfer deficit in schizophrenia, because schizophrenics failed to show consistently more errors in the right hand and the bimanual conditions.

Skin blood flow responses during sleep by laser Doppler flowmetry.

Skin surface blood flow at the fingertips was measured in a 21-year-old woman during sleep using laser Doppler flowmetry. Skin blood flow responses (SBFR) are transient reductions in skin blood flow of about 25s in duration. In our subject, SBFR showed a delay time of 8-9s from the onset of skin potential responses (SPR) and appeared more consistently than SPR. The frequency of SBFR decreased during non-rapid eye movement sleep, especially when the sleep stage became deep. These findings indicate the validity of SBFR as a discrete index of autonomic function during sleep.

[Analysis of the long-term prognosis for conjunctival malignant melanomas in Japan].

PURPOSE: To investigate the long-term prognosis for primary conjunctival malignant melanomas in Japan. MATERIALS & METHODS: We conducted a survey of 61 cases which had been reported in a 38-year period (1959 to 1996). We gathered information regarding the survival of patients, the post-operative follow-up period, the causes of death, and recurrences. Answers were obtained segarding 51 cases (84%). Detailed progress was identified in 23 of these cases. The survival rates were calculated using the Kaplan-Meier method. RESULTS: The survival rates were 95.1% after 1 year, 72.9% after 3 years, and 53.4% after 5 years. These values are relatively low compared with those reported in Europe and the United States.

Evaluation of sleep using ambulatory skin potential recording: differences between morning and evening type.

In order to validate the evaluation of sleep using cassette type ambulatory skin potential measurement system (C-SPA), sleep duration variables extracted from 24 h recordings were compared between two groups (16 of the intermediate type and 16 of the evening type) with different sleep-wake habits rated by Morningness and Eveningness Questionnaires (MEQ). Compared with the intermediate type, the evening type subjects go to bed and get up later, have difficulty in falling asleep and more frequently awaken during sleep. Thus, the sleep variables by C-SPA provide valuable information about duration of sleep and differentiate the sleep-wake habits.

Frontal lobe epilepsy with secondarily generalized 3 Hz spike-waves: a case report.

We report a case of frontal lobe epilepsy with bursts of 3 Hz spike-wave, often dominant in the left frontal lobe, that sometimes developed into a secondary bilateral generalization. This patient was a 69-year-old male with a history of epileptic seizures that began 3 months following a head injury at the age of 17. His seizures occurred two or three times a day, but after medication the frequency was halved. The seizures began with a feeling of heaviness of the head, accompanied by myoclonus at both angles of the mouth. Consciousness was clear for most of the seizures, which ranged from several seconds to many minutes. When seizures lasted for longer than 10 minutes, a temporary generalization accompanied by a loss of consciousness was sometimes observed. Neurological tests and cranial MRI yielded no abnormal local findings. The secondary generalized seizure seen in this case is the so called "secondary bilateral synchrony (SBS)." We succeeded in making an EEG recording of the bilateral generalization of a seizure discharge originating in the left frontal lobe, which until now has not been done. This case is direct proof that a primary frontal focus can give rise to SBS.

Effect of 5-hydroxytryptamine on gastrointestinal motility in conscious guinea-pigs.

Many studies have suggested that 5-hydroxytryptamine (5HT, serotonin) plays an important role in the control of gastrointestinal motility. However, most of these studies have been carried out on guinea-pig ileum in vitro. Therefore, we investigated the mechanisms of action of 5HT on gastrointestinal motility in conscious guinea-pigs. In order to investigate the effects of 5HT on gastrointestinal motility, extraluminal force transducers were sutured onto the serosal surfaces of the gastric antrum, duodenum and ileum and 5HT was infused intravenously. One of three types of 5HT antagonist or atropine was given before a 5HT infusion of 3.0 micrograms kg-1 min-1 was started. Regular cyclic patterns were observed from the gastric antrum to the ileum in both the fasted and fed states. 5HT increased the contraction amplitudes at all sites. 5HT-induced contractions in the gastric antrum and duodenum were significantly inhibited by methysergide, ondansetron and atropine, but not by ketanserin. In the ileum, only atropine inhibited 5HT-induced contractions. These results suggest that 5HT increases the gastrointestinal contraction amplitude mainly via a cholinergic pathway. 5HT3 receptors and 5HT1-like and/or 5HT2C receptors appear to be responsible for 5HT-induced gastric antral and duodenal contractions, but 5HT receptors other than 5HT1-like, 5HT2A, 5HT2C and 5HT3 receptors induce ileal contractions.

Effects of zonisamide on BAEP, SSEP and P300.

The effects of zonisamide on BAEP, SSEP and P300 were studied. The subjects were 12 patients (4 men and 8 women) with untreated epilepsy. Their ages ranged from 16 to 59 years, with a mean of 26.3 +/- 12.0 years. The daily dose of zonisamide was between 200 mg. to 600 mg. (2 to 6 tablets, 2.9 +/- 1.1 tablets on average). The serum concentrations of zonisamide ranged from 11.4 to 32.5 micrograms/ml, with a mean of 18.7 +/- 8.5 micrograms/ml 1 year after administration. Central conduction time and latency in BAEP and SSEP and amplitude, response time and latency in P300 were investigated. There were no significant differences in any of the tests. Zonisamide did not affect any of these evoked responses and may be less toxic to the central nervous system than other antiepileptic drugs.