The causes of forest cover loss in the hill forests in Bangladesh

The Hill Forests in Bangladesh have been depleted and degraded in volume, area, and quantity, thus requiring urgent forest protection by identifying the causes of forest loss. This study seeks to identify the fundamental causes of the shrinking forest cover in the Hill Forests in Bangladesh. The results indicate four sets of causes: (i) indigenous forest dwellers, having their own types of problems; (ii) migrants, who, because of problems in their places of origin, have decided to move to the forests; (iii) the timber industry, which, legal or not, are cutting too many trees; and (iv) the government through its Forest Department which is not able or willing to implement suitable policies to regulate the cutting trees and to prevent illegal cutting. Because it is a time consuming task to mitigate the first and second sets of factors, we recommend to involve forest dwellers in forestry practices as much as possible and taking necessary steps to alleviate the third and fourth sets and thereby reduce the rate of forest depletion. Accordingly, a number of strategies that should be adopted to halt the loss of remaining forest cover are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Strong ground motions from the 2011 off-the Pacific-Coast-of-Tohoku, Japan (Mw?=?9.0) earthquake obtained from a dense nationwide seismic network

The dense recordings of the K-NET and KiK-net nationwide strong motion network of 1,189 accelerometers show clearly the radiation and propagation properties of the strong ground motions associated with the 2011 off-the-Pacific Coast-of-Tohoku, Japan (Mw = 9.0) earthquake. The snapshots of seismic wave propagation reveal strong ground motions from this earthquake that originate from three large slips; the first two slips occurred over the plate interface of off-Miyagi at the southwest and the east of the hypocenter, and the third one just beneath the northern end of Ibaraki over the plate interface or in the crust. Such multiple shocks of this event caused large accelerations (maximum 1–2 G) and prolonged ground shaking lasting several minutes with dominant high-frequency (T < 1 s) signals over the entire area of northern Japan. On the other hand, ground motions of relatively longer–period band (T = 1–2 s), which caused significant damage to wooden-frame houses, were about 1/2–1/3 of those observed near the source area of the destructive 1995 Kobe, Japan (M = 7.3) earthquake. Also, the long-period (T = 6–8 s) ground motion in the Kanto (Tokyo) sedimentary basin was at an almost comparable level of those observed during the recent Mw = 7 inland earthquakes, but not as large as that from the former M = 8 earthquakes. Therefore, the impact of the strong ground motion from the present M = 9 earthquake was not as large as expected from the previously M = 7–8 earthquakes and caused strong motion damage only to short-scale construction and according to instruments inside the buildings, both have a shorter (T < 1 s) natural period.     

Glass veins in the unequilibrated eucrite Yamato 82202

The unequilibrated eucrite Yamato 82202 (Y82202) contains a network of relatively thick (up to 1 mm in width) glass veins. The host of the meteorite represents a monomict breccia composed of volcanic rock that crystallized > 4.3 Ga ago as a lava flow on the surface of 4 Vesta. The veins formed 3.90 ± 0.04 Ga ago, probably as a result of frictional melting associated with impact, under conditions of low effective oxygen fugacity and higher sulfur fugacity. The glass contains disordered structural elements characteristic of pyroxene and feldspar, reminiscent of the eucritic target lithology. The unequilibrated pyroxenes of the volcanic host and the pristine character of the glass indicate that this meteoritic material did not experience significant thermal metamorphism after initial crystallization of the lava. Hence, it was not affected by regional metamorphism caused by burial to a significant depth or by long-term contact metamorphism associated with a thick lava flow, large intrusion, or hot layer of impact ejecta. The meteorite resided at a shallow depth (though not at the surface) on 4 Vesta or on one of the vestoids until it was ejected and traveled to Earth, probably with other HED materials that have ³⁶Ar exposure ages of ∼13 Ma. These data suggest that the surface of the asteroid 4 Vesta has significant, though probably small, proportions of glass, as well as unequilibrated volcanic rock.     

FDM Simulation of an Anomalous Later Phase from the Japan Trench Subduction Zone Earthquakes

We investigated the development of a distinct later phase observed at stations near the Japan Trench associated with shallow, outer-rise earthquakes off the coast of Sanriku, northern Japan based on the analysis of three-component broadband seismograms and FDM simulations of seismic wave propagation using a heterogeneous structural model of the Japan Trench subduction zone. Snapshots of seismic wave propagation obtained through these simulations clearly demonstrate the complicated seismic wavefield constructed by a coupling of the ocean acoustic waves and the Rayleigh waves propagating within seawater and below the sea bottom by multiple reflections associated with shallow subduction zone earthquakes. We demonstrated that the conversion to the Rayleigh wave from the coupled ocean acoustic waves and the Rayleigh wave as they propagate upward along the slope of seafloor near the coast is the primary cause of the arrival of the distinct later phase at the station near the coast. Through a sequence of simulations using different structural models of the Japan Trench subduction zone, we determined that the thick layer of seawater along the trench and the suddenly rising sea bottom onshore of the Japanese island are the major causes of the distinct later phase. The results of the present study indicate that for realistic modeling of seismic wave propagation from the subduction zone earthquakes, a high-resolution bathymetry model is very crucial, although most current simulations do not include a water column in their simulation models.     

Recent advances in researches on physiologically active substances in holothurians

In this report, we reviewed recent literature on physiologically active substances from sea cucumbers （SCs） and their activities together with results obtained from our study. Preventive properties against lipid metabolism were reported in rats using a whole SC preparation with no particular constituent specified. Administration of the preparation lowered serum and hepatic cholesterol levels and improved the HDL/LDL ratio. These functions may be attributed to the stimulatory effect of the extract on the secretion of cholesterol in feces. Novel fucosylated chondroitin sulfates （FCSs） from Ludwigothurea grisea significantly induced fibroblast growth factor 2-dependent angiogenesis in human umbilical vein endothelial cells （HUVECs）. The proangiogenetic activity seemed attributable to the action of the sulfated fucose branches on the polysaccharide. SCs contain mycosporine-like amino acids （MAAs） that are capable of absorbing UV. A biogenetic precursor of MAAs was first reported in SCs. The anti-proliferative effects of a branched chain fatty acid from a sea cucumber on prostate cancer cells was reported with the activity of 5-lipoxygenase. Glycosphingolipid constituents in SCs have been systematically analyzed over the past ten years. The results showed that the gangliosides in several SCs differed from those of mammals in that a sialic acid of SC gangliosides directly binded to glucose of cerebroside. Neuritogenic activity of the glycosphingolipids was demonstrated in vitro experiments and may lead to the development of therapeutic products for neurological disorders. Our study also showed that sphingoid bases, the hydrolyzed products of glycosphingolipids from SCs, induced significant apoptosis in several tumor cell lines.     

Surface morphological features of boulders on Asteroid 25143 Itokawa

On the sub-kilometer S-type asteroid, 25143 Itokawa, some boulders on rough terrains seem to be exposed without any powdery material covering. Based on surface morphological features, there are two major types of boulders: one has rounded edges and corners (rounded boulders), while the other has angular edges and corners (angular boulders). The surface features of the rounded boulders suggest that they have hardness heterogeneity and that some may be breccias. The angular boulders appear to be more resistant to impact disruption than the rounded ones, which may be due to a difference in lithology. The major constituents of Itokawa may be LL chondrite-like brecciated lithology (rounded boulders) along with a remarkable number of boulders suggesting that lithology is atypical among LL chondrites (angular boulders). Some of both types of boulders contain intersecting and stepped planar foliations. Comparison with meteorite ALH76009 suggests that the planar foliations may be marks where rocks were torn apart. As lithified breccias cannot be formed on present-day sub-kilometer-sized Itokawa, it is reasonable that boulders with various lithologies on Itokawa were formed on its large ancestor(s). The rubble-pile structure of Itokawa suggested by its low density (∼1.9 g/cm³) indicates that boulders on Itokawa are reassembled fragments formed by catastrophic disruption of large ancestor(s).     

The Solar Optical Telescope for the Hinode Mission: An Overview

The Solar Optical Telescope (SOT) aboard the Hinode satellite (formerly called Solar-B) consists of the Optical Telescope Assembly (OTA) and the Focal Plane Package (FPP). The OTA is a 50-cm diffraction-limited Gregorian telescope, and the FPP includes the narrowband filtergraph (NFI) and the broadband filtergraph (BFI), plus the Stokes Spectro-Polarimeter (SP). The SOT provides unprecedented high-resolution photometric and vector magnetic images of the photosphere and chromosphere with a very stable point spread function and is equipped with an image-stabilization system with performance better than 0.01 arcsec rms. Together with the other two instruments on Hinode (the X-Ray Telescope (XRT) and the EUV Imaging Spectrometer (EIS)), the SOT is poised to address many fundamental questions about solar magnetohydrodynamics. This paper provides an overview; the details of the instrument are presented in a series of companion papers. M. Otsubo is a former NAOJ staff scientist.     

Is water-ice the carrier of the 3μm-absorption in infrared objects?

It is shown that Mie theory predictions of extinction for pure water-ice with the optical constant measured at 100 K do not fit in detail the observed ice absorption feature in infrared objects, although we attempt to explain the observations by considering size distribution and shape of the grains.In addition, based on a similarity between the ice band and the absorption band found in carbon stars, we feel it is questionable whether or not the ice band can really be attributed to the interstellar water-ice.