Velocity distribution of fragments of catastrophic impacts

Three dimensional velocities of fragments produced by laboratory impact experiments were measured for basalts and pyrophyllites. The velocity distribution of fragments obtained shows that the velocity range of the major fragments is rather narrow, at most within a factor of 3 and that no clear dependence of velocity on the fragment mass is observed. The NonDimensional Impact Stress (NDIS) defined by Mizutani et al. (1990) is found to be an appropriate scaling parameter to describe the overall fragment velocity as well as the antipodal velocity

Effects of Nanosecond Laser Fabrication on Bioactivity of Pure Titanium

AbstractWe are developing surface modification techniques for dental implants with the aim of reducing the time required to realize good adhesion between bone and implant surfaces. A nanosecond Nd:YVO4 laser was used to modify the surfaces of commercially pure titanium (CP Ti) disks and their bioactivities were then evaluated. The surfaces of the CP Ti disks were covered by lines after laser treatment. This treatment created complex microasperities of titania with rutile and anatase crystal structures. This results in the formation of hydroxyapatite on surfaces immersed in 1.5-times concentrated simulated body fluid for 7 days, whereas no hydroxyapatite was observed on conventionally polished surfaces that were immersed under the same conditions. This indicates that laser treatment improves the bioactivity of CP Ti, which is a critical property for osseointegrated implants

Categorization of indoor places by combining local binary pattern histograms of range and reflectance data from laser range finders

This paper presents an approach to categorize typical places in indoor environments using 3D scans provided by a laser range finder. Examples of such places are offices, laboratories, or kitchens. In our method, we combine the range and reflectance data from the laser scan for the final categorization of places. Range and reflectance images are transformed into histograms of local binary patterns and combined into a single feature vector. This vector is later classified using support vector machines. The results of the presented experiments demonstrate the capability of our technique to categorize indoor places with high accuracy. We also show that the combination of range and reflectance information improves the final categorization results in comparison with a single modality

Categorization of indoor places using the Kinect sensor

The categorization of places in indoor environments is an important capability for service robots working and interacting with humans. In this paper we present a method to categorize different areas in indoor environments using a mobile robot equipped with a Kinect camera. Our approach transforms depth and grey scale images taken at each place into histograms of local binary patterns (LBPs) whose dimensionality is further reduced following a uniform criterion. The histograms are then combined into a single feature vector which is categorized using a supervised method. In this work we compare the performance of support vector machines and random forests as supervised classifiers. Finally, we apply our technique to distinguish five different place categories: corridors, laboratories, offices, kitchens, and study rooms. Experimental results show that we can categorize these places with high accuracy using our approach

Survival motor neuron (SMN) protein in the spinal anterior horn cells of patients with sporadic amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease involving mainly the upper and lower motor neurons of adult humans. With regard to the pathomechanism of spinal anterior horn cell (AHC) degeneration in ALS, copy number abnormalities of the survival motor neuron (SMN) genes have been reported in sporadic (s) ALS. SMN protein is the protein responsible for the pathogenesis of spinal muscular atrophy (SMA), an autosomal recessive disease characterized by lower motor neuron loss and muscle atrophy. The disease is caused by deficiency of SMN protein induced by mutation of one of the SMA-associated genes, SMN1. To clarify the role of SMN protein in the degeneration of spinal AHCs in sALS, we examined the amount of cytoplasmic SMN protein in individual AHCs using cytofluorophotometry in 9 patients with sALS and 10 control subjects. It was found that: 1) SMN protein was present in the cytoplasm, nucleus and nucleolus of AHCs and in the nucleus of glial cells, 2) expression of SMN protein in AHCs was significantly associated with cell size in both sALS patients and controls, 3) expression of SMN protein per unit area in AHCs was similar in sALS patients and controls. These findings suggest that: 1) the amount of SMN protein in the cytoplasm of AHCs is strictly controlled in accordance with cell size, in both sALS patients and controls, 2) the amount of SMN protein in the AHCs of sALS patients may be reduced when the AHCs are atrophic, and 3) decrease of SMN protein in the AHCs of sALS patients may be a secondary, and not primary, phenomenon according to their sizes.ArticleBRAIN RESEARCH. 1372:152-159 (2011)journal articl

Planetary Interiors

This report identifies two main themes to guide planetary science in the next two decades: understanding planetary origins, and understanding the constitution and fundamental processes of the planets themselves. Within the latter theme, four specific goals related to interior measurements addressing the theme. These are: (1) Understanding the internal structure and dynamics of at least one solid body, other than the Earth or Moon, that is actively convecting, (2) Determine the characteristics of the magnetic fields of Mercury and the outer planets to provide insight into the generation of planetary magnetic fields, (3) Specify the nature and sources of stress that are responsible for the global tectonics of Mars, Venus, and several icy satellites of the outer planets, and (4) Advance significantly our understanding of crust-mantle structure for all the solid planets. These goals can be addressed almost exclusively by measurements made on the surfaces of planetary bodies

Thermal diffusivity of Mg_2SiO_4, Fe_2SiO_4, and NaCl at high pressures and temperatures

The pressure and temperature variations of thermal diffusivity of poly crystalline Mg_2SiO_4 have been measured for the range 24 to 50 kb and 400° to 1300°K. Effect of the olivine‐spinel phase transition on thermal diffusivity of Fe_2SiO_4 was studied at 48.5 kb for the temperature range 350° to 650°K. Synthetic samples with grain size 1 to 5 microns were used. For the pressure range studied, the reciprocal of thermal diffusivity 1/κ of Mg_2SiO_4 increases almost linearly with temperature up to about 1200°K, as expected from the theory of phonon conduction, but is nearly constant above that temperature. The 1/κ versus temperature curve of Fe_2SiO_4 (olivine) is nearly straight up to 700°K, where it becomes slightly convex. The thermal diffusivity of NaCl is measured under similar conditions for comparison with Bridgman's data. The agreement is reasonably good. The pressure derivative ∂κ/∂P, at P = 40 kb is 1.8 × 10^)−4) cm^2/sec kb (at 700°K) and 0.8 × 10^(−4) cm^2/sec kb (at 1100°K) for Mg_2SiO_4, and 4.7 × 10^(−4) cm^2/sec kb (at 700°K) for NaCl. This pressure dependence can be explained by the theory of phonon conduction. The thermal diffusivity of Fe_2SiO_4 (spinel) is about 1.5 times that of Fe_2SiO_4 (olivine) over the range 350° to 650°K. The effect of radiative heat transfer in Mg_2SiO_4 is discussed. The photon mean free path is estimated to be 0.3 mm at 1400°K