Graphite porous materials have been successfully used in an aerostatic bearing. This is because graphite porous materials have a lower permeability than porous metal, which makes it possible to achieve a higher stiffness in aerostatic bearings. However, aerostatic porous bearings have a disadvantage in that they are prone to cause pneumatic hammer instability. Therefore, a restricted layer which has a permeability lower than the bulk of the porous material is usually formed on the bearing surface to avoid this instability. In this paper, the static characteristics of aerostatic porous journal bearings with a surface-restricted layer are investigated theoretically and experimentally. In addition, the effects of a surface-restricted layer on the static characteristics are discussed for two types of loads, symmetrical and coupled. NOTATIONe c shaft displacement at the bearing end for coupled loads (m) e s shaft displacement for symmetrical loads (m) dr s thickness of a surface-restricted layer (m) ds thickness of end seal (m) D diameter of the shaft (m) h local bearing clearance (m) h 0 average bearing clearance (m) k permeability of the bulk of porous material (m 2 ) k 0 permeability of a restricted layer (m 2 ) L bearing length (m) L 1 width of circumferential air supply groove (m) m tilt moment (N m) M dimensionless tilt moment h 0 m= …p s ¡ p a †DL 2 £ ¤ p a ambient pressure (Pa) p s supply pressure (Pa) p 1 , p 2 pressures in porous material and bearing clearance (Pa) P dimensionless pressureˆ…p ¡ p a †=p a q mass¯owrate (kg/s) q r , q z , q y mass¯owrates in the r, z, y directions (kg/s) q v volume¯owrate (m 3 /s) Q mass¯ow reduction ratio r, z, y coordinates in the r, z, y directions r s radial thickness of porous material (m) r 0 radius of the bearing (m) r 1 outer radius of porous material (m) < gas constant T temperature (K) w load-carrying capacity (N) W dimensionless load-carrying capacitŷ w= …p s ¡ p a †DL ‰ Š Z dimensionless coordinate in the z directionˆz=L a parameter pertaining to a surface restrictorˆ…k 0 /k †/…dr s /r s † e c eccentricity ratio at the bearing end for coupled loadsˆe c L/…2h 0 † e s eccentricity ratio for symmetrical loadsˆe s /h 0 r 1 , r 2 densities of air in porous material and bearing clearance (kg/m 3 )

Background Pneumonia is a common cause of illness and death of the elderly in Japan. Its prevalence is escalating globally with the aging of population. To describe the latest trends in pneumonia hospitalizations, especially aspiration pneumonia (AP) cases, we assessed the clinical records of pneumonia patients admitted to core acute care hospitals in Miyagi prefecture, Japan. Methods A retrospective multi-institutional joint research was conducted for hospitalized pneumonia patients aged ≥20 years from January 2019 to December 2019. Clinical data of patients were collected from the medical records of eight acute care hospitals. Results Out of the 1,800 patients included in this study, 79% of the hospitalized pneumonia patients were aged above 70 years. The most common age group was in the 80s. The ratio of AP to total pneumonia cases increased with age, and 692 out of 1,800 patients had AP. In univariate analysis, these patients had significantly older ages, lower body mass index (BMI), a lower ratio of normal diet intake and homestay before hospitalization, along with more AP recurrences and comorbidities. During hospitalization, AP patients had extended fasting periods, more swallowing assessments and interventions, longer hospitalization, and higher in-hospital mortality rate than non-AP patients. A total of 7% and 2% AP patients underwent video endoscopy and video fluorography respectively. In multivariate analysis, lower BMI, lower C-reactive protein, a lower ratio of homestay before hospitalization, a higher complication rate of cerebrovascular disease, dementia, and neuromuscular disease were noted as a characteristic of AP patients. Swallowing interventions were performed for 51% of the AP patients who had been hospitalized for more than two weeks. In univariate analysis, swallowing intervention improved in-hospital mortality. Lower AP recurrence before hospitalization and a lower ratio of homestay before hospitalization were indicated as characteristics of AP patients of the swallowing intervention group from multivariate analysis. Change in dietary pattern from normal to modified diet was observed more frequently in the swallowing intervention group. Conclusion AP accounts for 38.4% of all pneumonia cases in acute care hospitals in Northern Japan. The use of swallowing evaluations and interventions, which may reduce the risk of dysphagia and may associate with lowering mortality in AP patients, is still not widespread.

Respiratory epithelial adenomatoid hamartomas (REAHs) are rare tumors occurring in the nasal cavity and sinuses, and their etiology is unknown. REAH is a relatively recently established lesion and is often misdiagnosed as nasal polyposis or other tumors. Preoperative endovascular embolization for sinonasal tumors is now widely accepted as an effective method to reduce blood loss, soften the tumor, and facilitate surgical procedures. However, to the best of our knowledge, there are no reports of the requirement for preoperative embolization in the management of REAH. Here, we present a 70-year-old man with an easily bleeding REAH of the olfactory cleft, vascularized by branches of the bilateral internal and external carotid arteries. We removed the tumor endoscopically after preoperative embolization of the bilateral sphenopalatine arteries. Histological investigation revealed an intratumoral hemorrhage accompanying the REAH, with no evidence of a residual or recurrent tumor during the last follow-up at 3 months. In conclusion, accurate preoperative diagnosis and proper preoperative interventions such as embolization are needed for safe and adequate treatment of REAHs that have an abundant blood flow.

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