A Novel Co-operative Channel Assignment Scheme for Indoor Base Stations

This paper presents a co-operation technique ofchannel assignment (CA) for indoor base stations (BSs). IndoorBSs are most of the time deployed by users in an ad-hoc mannerwhich makes prior network planning by network operatorsimpossible. If the same pool of radio resources (e.g channels) isused by close BSs, co-operation between these BSs is vital forresolving problems such as interference. In the proposed scheme,femtocell base station (FBS), which is a typical example of indoorBS, is considered. FBSs in close proximity exchange UE-assisted(User Equipment) measured reference power information, andbased on individual position of each FBS, inter-BS interaction isused to form clusters. In each cluster, the cluster-head (CH) useschannel assignment tables to assign channel resources to clustermembers(CMs) in a distributed manner. This scheme helps toensure that the interest of neighbor BSs is always consideredwhenever a BS makes use of the available network resources.Our simulation results show that co-operative CA using a clusterbasedapproach yields higher average user throughput thanautonomous channel selection by individual BSs

Changes in Vibrational Properties of Wetwood of Japanese Fir (Abies Sachalinensis Mast) with Time During Drying

Temporal changes in vibrational properties of wetwood of Japanese fir (Abies sachalinensis Mast.) during a drying process were investigated. Specimens were cut from wetwood defined as heartwood with extremely high moisture content and normal wood whose moisture content was not so high, and matched in the R-direction. Green and water-saturated wood specimens were prepared. The specimens and the vibration testing system were put in an electric drying oven, where a free-free vibration test was conducted at intervals of 5 to 20 minutes. When the green specimens were used, the resonance frequency and loss tangent of both wetwood and normal wood reached the minimum and maximum, respectively, early in the drying. The minimum and maximum of the wetwood were smaller and larger than those of the normal wood. These differences between the wetwood and normal wood were mainly caused by the differences in initial moisture content because such differences, which existed in the green wood, disappeared once a water-saturated condition was reached

Comparisons of Shear Stress/Shear Strain Relations of Wood Obtained By Iosipescu And Torsion Tests

In this paper, we compared the shear stress/shear strain relations of wood obtained by Iosipescu and torsion tests.Quartersawn boards of Sitka spruce (Picea sitchensis Carr.) and shioji (Japanese ash, Fraxinus spaethiana Lingelsh.) provided the specimens. Iosipescu tests were conducted with specimens loaded in the radial direction, and the shear stress/shear strain relations were obtained. Shear stress/shear strain relations were obtained independently of the Iosipescu tests by torsion tests of rectangular bars. The following results were obtained:(1) The shear moduli, shear yield stresses, and shear strengths obtained from both methods showed good agreement with each other, except for the shear strength of ash.(2) As for spruce, the difference between the shear stress/shear strain relations obtained by Iosipescu and torsion tests was significant in the 5% significance level, whereas that for the ash was not significant.(3) Although the Iosipescu test can derive the shear stress/shear strain relation directly, it has the drawback that failure occurs earlier than with the torsion test. In contrast, the torsion test has the drawback that the procedure for obtaining the stress/strain relation is quite complicated. In determining the shear stress/shear strain relation of wood properly, shear stress/shear strain data should be measured more frequently by these methods

Superlattice formation lifting degeneracy protected by non-symmorphic symmetry through a metal-insulator transition in RuAs

The single crystal of RuAs obtained by Bi-flux method shows obvious successive metal-insulator transitions at T_MI1~255 K and T_MI2~195$ K. The X-ray diffraction measurement reveals a formation of superlattice of 3x3x3 of the original unit cell below T_MI2, accompanied by a change of the crystal system from the orthorhombic structure to the monoclinic one. Simple dimerization of the Ru ions is nor seen in the ground state. The multiple As sites observed in nuclear quadrupole resonance (NQR) spectrum also demonstrate the formation of the superlattice in the ground state, which is clarified to be nonmagnetic. The divergence in 1/T_1 at T_MI1 shows that a symmetry lowering by the metal-insulator transition is accompanied by strong critical fluctuations of some degrees of freedom. Using the structural parameters in the insulating state, the first principle calculation reproduces successfully the reasonable size of nuclear quadrupole frequencies for the multiple As sites, ensuring the high validity of the structural parameters. The calculation also gives a remarkable suppression in the density of states (DOS) near the Fermi level, although the gap opening is insufficient. A coupled modulation of the calculated Ru d electron numbers and the crystal structure proposes a formation of charge density wave (CDW) in RuAs. Some lacking factors remain, but it shows that a lifting of degeneracy protected by the non-symmorphic symmetry through the superlattice formation is a key ingredient for the metal-insulator transition in RuAs.Comment: 10 pages, 10 figure

Point Cloud-based Proactive Link Quality Prediction for Millimeter-wave Communications

This study demonstrates the feasibility of point cloud-based proactive link quality prediction for millimeter-wave (mmWave) communications. Previous studies have proposed machine learning-based methods to predict received signal strength for future time periods using time series of depth images to mitigate the line-of-sight (LOS) path blockage by pedestrians in mmWave communication. However, these image-based methods have limited applicability due to privacy concerns as camera images may contain sensitive information. This study proposes a point cloud-based method for mmWave link quality prediction and demonstrates its feasibility through experiments. Point clouds represent three-dimensional (3D) spaces as a set of points and are sparser and less likely to contain sensitive information than camera images. Additionally, point clouds provide 3D position and motion information, which is necessary for understanding the radio propagation environment involving pedestrians. This study designs the mmWave link quality prediction method and conducts realistic indoor experiments, where the link quality fluctuates significantly due to human blockage, using commercially available IEEE 802.11ad-based 60 GHz wireless LAN devices and Kinect v2 RGB-D camera and Velodyne VLP-16 light detection and ranging (LiDAR) for point cloud acquisition. The experimental results showed that our proposed method can predict future large attenuation of mmWave received signal strength and throughput induced by the LOS path blockage by pedestrians with comparable or superior accuracy to image-based prediction methods. Hence, our point cloud-based method can serve as a viable alternative to image-based methods.Comment: Submitted to IEEE Transactions on Machine Learning in Communications and Networkin

Transmission of bacterial infections to healthcare workers during intubation and respiratory care of patients with severe pneumonia

Exposure of healthcare workers to patients with rapidly fatal infections invariably raises concerns regarding the risk of occupational acquisition. We describe acquisition of Streptococcus pyogenes by 2 nurses from a patient with fatal pneumonia and review previously reported cases of transmission of bacterial pathogens from patients with pneumonia to healthcare workers

Threshold Core Temperatures for Tail Vasodilation During General Warming in Spontaneously Hypertensive Rats (SHR) and Stroke-prone SHR (SHRSP)

In order to study heat dissipation ability of spontaneously hypertensive rats, threshold core temperatures for occurrence of the tail vasodilation were compared among adult male spontaneously hypertensive rats (SHR), stroke-prone SHR (SHRSP) and Wistar-Kyoto rats (WKY). Mean age of month (M.) and mean systolic blood pressure were 8.4±0.5 M; 205±5 mmHg for SHR, 7.2±0.6 M; 240±8 mmHg for SHRSP and 7.6±1.1 M; 140±6 mmHg for WKY. For the measurement, each rat was placed into a small wire-mesh cage for a loose restraint. Rectal temperature, tail skin temperature and air temperature were simultaneously recorded by means of thermistor probes or copper-constantan thermocouples. Air temperature was gradually raised at a constant rate of 0.17℃/min. Stepwise changes in the tail skin temperature were observed during the gradual elavation of the air temperature. The beginning of the tail vasodilation was detected by the 1st increase in tail skin temperature. Mean threshold core temperature for the 1st vasodilation in SHR, SHRSP and WKY were, 38.9±0.1℃, 38.4±0.1℃ and 38.0±0.1℃, respectively. Threshold core temperatures for the 1st vasodilation in SHR and SHRSP were significantly high compared to that in WKY, while the threshold in SHRSP was significantly lower than SHR. Mean values of threshold Ta for the 1st tail vasodilation in SHR, SHRSP and WKY were 30.1±0.5℃, 29.9±0･6℃ and 29.7±0.5℃, respectively. There was no statistical significance among these values. These results are consistent with the fact that the core temperature in adult SHRSP is not always high as SHR, even though blood pressure of SHRSP is higher than SHR. And these facts also suggest that high systemic blood pressure itself may not cause developing high core temperature in these genetically hypertensive rats

Endurance of larch forest ecosystems in eastern Siberia under warming trends

第6回極域科学シンポジウム分野横断セッション：[IA] 急変する北極気候システム及びその全球的な影響の総合的解明―GRENE北極気候変動研究事業研究成果報告2015―11月19日（木）　国立極地研究所１階交流アトリウ