Impact of satellite gravity missions on glaciology and Antarctic Earth sciences

Satellite gravity missions in the 21st Century are expected to be beneficial to multi-disciplinary scientific objectives. Especially, the Gravity Recovery And Climate Experiment (GRACE) and its follow-on missions will provide not only data for precise gravity mapping but also time series of global gravity field coefficients at intervals of about 15 days to two months. These data are precise enough to reveal the temporal variations of the gravity fields due to mass redistribution in and on the Earth. From the viewpoint of Earth sciences in the Antarctic region, the data are expected to contribute to studies of ice sheet mass balance and postglacial rebound as well as other geodetic and geophysical problems. These issues have been mainly investigated based on the degree variance analyses of the gravity field so far. In this paper, we briefly review the gravity mission data from the viewpoint of along track geoid height variations which are more direct results of the mass variations, and then discuss some of the issues related to in-situ observations

Installation of the superconducting gravimeter CT(#043) at Syowa Station, Antarctica

During the wintering period of the 44th Japanese Antarctic Research Expedition (JARE-44: February 2003 to January 2004), a new superconducting gravimeter CT(#043) with a cryocooler was installed and tested to replace the former TT70(#016) at Syowa Station, Antarctica. The CT(#043) has design sensitivity of 1nGal (1×10^(-11)m/s^2) to study the Earth\u27s dynamics in tidal and longer-period bands. A new type of diaphragm was used to effectively isolate the vibration from the refrigerator cold-head and to prevent solid air contamination from entering the Dewar. A real-time remote monitoring system including a Web camera for diagnostics from Japan has also been installed

Future efforts to contribute to the International Height Reference System (IHRS)

The Tenth Symposium on Polar Science/Special session: [S] Future plan of Antarctic research: Towards phase X of the Japanese Antarctic Research Project (2022-2028) and beyond, Tue. 3 Dec. / Entrance Hall (1st floor) at National Institute of Polar Research (NIPR

Calibration of the superconducting gravimeter CT#043 with an absolute gravimeter FG5#210 at Syowa Station, Antarctica

For the purpose of calibration of the superconducting gravimeter (SG) model CT#043 at Syowa Station, Antarctica, we carried out parallel observations with the absolute gravimeter (AG) FG5#210. Although the AG measurements were conducted from December 31, 2003 to February 9, 2004, SG measurements before January 17 are found to have suffered artificial sensitivity change. We finally adopted data from January 17 to February 1, 2004, and obtained the scale factor of CT#043 as -59.461 ±0.079μGal/volt by linear regression analysis. The result achieved a relative accuracy of around 0.1%, which is important to modern precise tidal analysis. We also determined the scale factor by comparing the data of parallel observations with the SG TT70#016. Both values showed good agreement, supporting the reliability of the above mentioned value

Synthesis of Non-Steroidal Estrogen Receptor Antagonists R1128 A, B, C, and D via an Oxazoline-Promoted Iterative ortho-Lithiation Strategy

A concise total synthesis of non-steroidal estrogen receptor antagonists R1128 A–D (1a–1d) has been achieved using iterative ortho-lithiation of 2-(4-methoxyphenyl)-4,4-dimethyloxazoline (3) as the key reaction

Sr3(Al3+xSi13−x)(N21−xO2+x):Eu2+ (x ∼ 0): a monoclinic modification of Sr-sialon

The structure of the title compound, Sr-bearing oxonitrido­aluminosilicate (Sr-sialon), contains two types of channels running along the a axis, with the three unique Sr atoms (coordinatioon number seven) residing in the larger one. The channels cross a three-dimensional Si–Al–O–N network, in which the Si and Al atoms are in a tetra­hedral coordination with N and O atoms. The chemical composition of the crystal is close to Sr3Al3Si13N21O2 (tris­trontium trialuminium trideca­silicon henicosa­nitride dioxide), which can be expressed as a mixture of SrSiN2, Si3N4, AlN, and SiO2 components in the molar ratio 3:3:3:1. The crystal studied was metrically orthorhombic, consisting of four twin components related by metric merohedry

Reconstruction of rabbit mandibular bone defects using carbonate apatite honeycomb blocks with an interconnected porous structure

Carbonate apatite (CO3Ap) granules are useful as a bone substitute because they can be remodeled to new natural bone in a manner that conforms to the bone remodeling process. However, reconstructing large bone defects using CO3Ap granules is difficult because of their granular shape. Therefore, we fabricated CO3Ap honeycomb blocks (HCBs) with continuous unidirectional pores. We aimed to elucidate the tissue response and availability of CO3Ap HCBs in the reconstruction of rabbit mandibular bone defects after marginal mandibulectomy. The percentages of the remaining CO3Ap area and calcified bone area (newly formed bone) were estimated from the histological images. CO3Ap area was 49.1 ± 4.9%, 30.3 ± 3.5%, and 25.5 ± 8.8%, whereas newly formed bone area was 3.0 ± 0.6%, 24.3 ± 3.3%, and 34.7 ± 4.8% at 4, 8, and 12 weeks, respectively, after implantation. Thus, CO3Ap HCBs were gradually resorbed and replaced by new bone. The newly formed bone penetrated most of the pores in the CO3Ap HCBs at 12 weeks after implantation. By contrast, the granulation tissue scarcely invaded the CO3Ap HCBs. Some osteoclasts invaded the wall of CO3Ap HCBs, making resorption pits. Furthermore, many osteoblasts were found on the newly formed bone, indicating ongoing bone remodeling. Blood vessels were also formed inside most of the pores in the CO3Ap HCBs. These findings suggest that CO3Ap HCBs have good osteoconductivity and can be used for the reconstruction of large mandibular bone defects

Postharvest Properties of Ultra-Late Maturing Peach Cultivars and Their Attributions to Melting Flesh (M) Locus: Re-evaluation of M Locus in Association With Flesh Texture

The postharvest properties of two ultra-late maturing peach cultivars, "Tobihaku" (TH) and "Daijumitsuto" (DJ), were investigated. Fruit were harvested at commercial maturity and held at 25 degrees C. TH exhibited the characteristics of normal melting flesh (MF) peach, including rapid fruit softening associated with appropriate level of endogenous ethylene production In contrast, DJ did not soften at all during 3 weeks experimental period even though considerable ethylene production was observed. Fruit of TH and DJ were treated with 5,000 ppm of propylene, an ethylene analog, continuously for 7 days. TH softened rapidly whereas DJ maintained high flesh firmness in spite of an increase in endogenous ethylene production, suggesting that DJ but not TH lacked the ability to be softened in response to endogenous and exogenous ethylene/propylene. DNA-seq analysis showed that tandem endo-polygalacturonase (endoPG) genes located at melting flesh (M) locus, Pp-endoPGM (PGM), and Pp-endoPGF (PGF), were deleted in DJ. The endoPG genes at M locus are known to control flesh texture of peach fruit, and it was suggested that the non-softening property of DJ is due to the lack of endoPG genes. On the other hand, TH possessed an unidentified M haplotype that is involved in determination of MF phenotype. Structural identification of the unknown M haplotype, designated as M-0, through comparison with previously reported M haplotypes revealed distinct differences between PGM on M-0 haplotype (PGM-M-0) and PGM on other haplotypes (PGM-M-1). Peach M haplotypes were classified into four main haplotypes: M-0 with PGM-M-0; M-1 with both PGM-M-1 and PGF; M-2 with PGM-M-1; and M-3 lacking both PGM and PGF. Re-evaluation of M locus in association with MF/non-melting flesh (NMF) phenotypes in more than 400 accessions by using whole genome shotgun sequencing data on database and/or by PCR genotyping demonstrated that M-0 haplotype was the common haplotype in MF accessions, and M-0 and M-1 haplotypes were dominant over M-2 and M-3 haplotypes and co-dominantly determined the MF trait. It was also assumed on the basis of structural comparison of M haplotypes among Prunus species that the ancestral haplotype of M-0 diverged from those of the other haplotypes before the speciation of Prunus persica

Field measurements of absolute gravity in East Antarctica

This paper reports the results of field-based absolute gravity measurements aimed at detecting gravity change and crustal displacement caused by glacial isostatic adjustment. The project was initiated within the framework of the 53rd Japanese Antarctic Research Expedition (JARE53). Absolute gravity measurements, together with GPS measurements, were planned at several outcrops along the Prince Olav Coast and Sôya Coast of East Antarctica, including at Syowa Station. Since the icebreaker Shirase (AGB 5003) was unable to moor alongside Syowa Station, operations were somewhat restricted during JARE53. However, despite this setback, we were able to complete measurements at two sites: Syowa Station and Langhovde. The absolute gravity value at the Syowa Station IAGBN (A) site, observed using an FG-5 absolute gravimeter (serial number 210; FG-5 #210), was 982 524 322.7±0.1 μGal, and the gravity change rate at the beginning of 2012 was –0.26 μGal∙a-1. An absolute gravity value of 982 535 584.2±0.7 μGal was obtained using a portable A-10 absolute gravimeter (serial number 017; A-10 #017) at the newly located site AGS01 in Langhovde

Interaction of the solid Earth and the Antarctic ice sheet

第6回極域科学シンポジウム分野横断セッション：[IG] 全球環境変動を駆動する南大洋・南極氷床11月17日（火）　国立極地研究所 2階 大会議