Origin and hydrodynamics of xylem sap in tree stems, and relationship to root uptake of soil water

Although 10 years have passed since Japan's Fukushima nuclear accident, the future radiation risk from ¹³⁷Cs contamination of wood via root uptake is a serious concern. We estimated the depth at which the roots of evergreen coniferous sugi (Cryptomeria japonica) and broadleaf deciduous konara (Quercus serrata) trees actively take up soil water by using positive δD values from the artificial D₂O tracer and seasonal changes in the δ¹⁸O values of soil water as a natural environmental tracer. We compared the tracer concentration changes in xylem sap with those in the soil water and ascertained that both tree species primarily took up water from a depth of 20 cm, though with mixing of water from other depths. Using sap hydrodynamics in tree stems, we found that water circulation was significantly slower in heartwood than in sapwood. Heartwood water was not supplied by direct root uptake of soil water. The measured diffusion coefficients for D₂O, K⁺, Cs⁺, and I⁻ in xylem stems were greater in sapwood than in heartwood, and their magnitude was inversely correlated with their molecular weights. The distribution of D₂O and ¹³⁷Cs concentrations along the radial stem could be explained by simulations using the simple advective diffusion model

The Risk of Liquefaction Associated with Water Head Fluctuation in the Low-lying Area of Tokyo

 In the wide area of the eastern part of Tokyo, the ground level is less than mean sea level. This area is more vulnerable to disasters than other areas. If large flood damage such as storm surge should occur in this area, the disaster would be a long-term catastrophe. On the coast of Tokyo Bay, countermeasures have been taken by tide embankments and floodgates. However, considering the damage scale when it occurs, an analysis in this area is very important. In this area, ground settlement occurred and groundwater head dropped because groundwater excessively withdrew by the industrial purpose during the period of economic growth. Currently, the groundwater head recovers and the ground settlement has been subsided. However, due to the groundwater head fluctuation, pore water pressure distribution had been different from hydrostatic pressure distribution. Therefore, in the analysis in this area, it is necessary to consider past groundwater head fluctuation. In this research, the ground settlement and the distribution of pore water pressure are simulated from groundwater level fluctuation over the past 100 years. Then, we conducted the seismic analysis by input the distribution of effective stress calculating from the simulated ground water pressure. The sites analyzed in this research are Tokyo Sea Life Park at the mouth of Arakawa River

Among-Clone Variations of Anatomical Characteristics and Wood Properties in Tectona Grandis Planted in Indonesia

Anatomical characteristics (vessel diameter [VD], fiber wall thickness [FWT], fiber diameter [FD], vessel element length [VEL], and fiber length [FL]) and wood properties (basic density [BD] and compressive strength parallel to grain [CS] in the green condition) were determined for 27 12-yr-old teak trees planted in Java Island, Indonesia. The mean values of VD, FWT, FD, VEL, FL, BD, and CS were 188 μm, 2.78 μm, 23.4 μm, 284 μm, 1.42 mm, 510 kg/m3, and 37.5 MPa, respectively. Significant differences in VEL, BD, and CS occurred among the nine clones. Moderate to high values of repeatability were obtained for FD, VEL, BD, and CS, indicating that these characteristics are genetically controlled. Radial variation of FL with respect to relative distance showed almost the same pattern for two different radial growth rates (faster and slower) at the same age, suggesting that xylem maturation in teak trees depends on cambial age rather than stem diameter

Technical Note: Solid Wood Properties of Eucalyptus Camaldulensis Planted for Pulpwood Production in Thailand

Solid wood properties of two Eucalyptus camaldulensis clones (clone A and clone B), derived from different pulp and paper companies and planted in Thailand for pulpwood production, were investigated to evaluate the possibility for lumber production. Clone A had significantly higher Young's modulus, greater density, and straighter grain compared with clone B. These results suggest that some clones may have more favorable properties for lumber production than others. Thus, wood properties should be included in clonal trials and early testing of this species

Wood Property Variation in Acacia Auriculiformis Growing in Bangladesh

This study examined the radial variations of wood properties in 11-yr-old Acacia auriculiformis grown in Bangladesh having diameters of 222 ± 38 mm. The basic density, fiber length, and fiber length increment increased up to about 80 mm radial distance from the pith and then were almost constant toward the bark. The compressive strength (CS) increased from the pith to 50 mm and then became nearly constant to the bark. Conversely, the specific compressive strength, the ratio of CS to air-dried density, was almost constant from pith to bark, indicating positive relationships. However, the air-dried density explained only 50% variation of the CS. On the basis of radial variation of basic density, the core wood and outer wood boundary can be delineated at 70 - 90 mm from the pith. Similarly, the fiber length and fiber length increment curves showed that this boundary could be marked at 60 - 90 mm from the pith. The selected wood properties except CS varied significantly among the trees, which indicated the potential of tree selection for wood quality improvement through tree breeding

Densification of layered firn of the ice sheet at Dome Fuji, Antarctica

第6回極域科学シンポジウム[OM] 極域気水圏11月16日（月）　国立極地研究所１階交流アトリウ

Photon Pair Generation in Silicon Micro-Ring Resonator with Reverse Bias Enhancement

Photon sources are fundamental components for any quantum photonic technology. The ability to generate high count-rate and low-noise correlated photon pairs via spontaneous parametric down-conversion using bulk crystals has been the cornerstone of modern quantum optics. However, future practical quantum technologies will require a scalable integration approach, and waveguide-based photon sources with high-count rate and low-noise characteristics will be an essential part of chip-based quantum technologies. Here, we demonstrate photon pair generation through spontaneous four-wave mixing in a silicon micro-ring resonator, reporting a maximum coincidence-to-accidental (CAR) ratio of 602 (+-) 37, and a maximum photon pair generation rate of 123 MHz (+-) 11 KHz. To overcome free-carrier related performance degradations we have investigated reverse biased p-i-n structures, demonstrating an improvement in the pair generation rate by a factor of up to 2, with negligible impact on CAR.Comment: 5 pages, 3 figure

Metamorphism of layered firn at Dome Fuji, Antarctica: Evolution of relations between Near-infrared reflectivity and the other textural/chemical properties

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Wed. 4 Dec. / 2F Auditorium, National Institute of Polar Researc

那須山系におけるミヤマナラの更新様式

This study aimed to clarify clonal structure and reproductive modes, layering (asexual) and/or seedling regeneration (sexual), of Quercus crispula var. horikawae using eight nuclear EST-SSR markers; the species has stunt creeping multiple stems and occurs in pseudo-alpine zone of the mountains in the Sea of Japan side. This study was conducted in an isolated stand (alt. 1,570 m) of the species near Ohtoge-pass in Mts. Nasu, northern Tochigi Prefecture. DNA was extracted from leaves of 92 stems that did not have any distinct connection of roots and creeping stems above the ground. The results of DNA analysis indicated that the stand consisted of four genets (clones). Genet A, which had 87 stems (ramets), occupied throughout the study plot. The other clones (B, C and D), which were composed of 1-3 ramets, might be derived from seedling regeneration. In conclusion, reproductive modes in the stand were likely to be dominated by layering regeneration resulted from the creeping of stems rather than seedling regeneration that rarely occurred