The noninferiority of ME alone to ME with LLND was not confirmed in the intent-to-treat analysis. ME with LLND had a lower local recurrence, especially in the lateral pelvis, compared to ME alone.

The ground state of the typical spin-1 linear-chain Heisenberg antiferromagnet Ni(C2H8N2)2-N02(C104) containing a small amount of Cu^^ is studied by the electron-spin-resonance (ESR) technique. The ESR results are quantitatively explained by the model that the valence bonds are broken at the Cu""*" sites resulting in spin-j states at the Ni^"^ sites neighboring the Cu^"^. Thus the present study gives experimental evidence for the existence of the valence-bond-solid ground state in 5 = 1 linear-chain Heisenberg antiferromagnets.

Abstract. The spatial variability of the b value of the frequency-magnitude relationship and the decay rate of aftershocks as described by the p value of the modified Omori law is investigated. By using dense spatial grids we map out the distribution of b and p values within the Landers, Northridge, Morgan Hill, and Kobe aftershock sequences. Considerable spatial variability is found, with b values of independent subvolumes ranging from 0.6 to 1.4, and p values ranging from 0.6 to 1.8. These systematic and statistically highly significant differences argue that it is an oversimplification to assign one single p and b value to an aftershock sequence that extends up to 100 km. The spatial distribution of these two parameters is compared with the slip distribution during the mainshock, suggesting that the areas of largest slip release correlate with high b value regions. We hypothesize that the frictional heat created during the event may influence the p value distribution within an aftershock zone, while applied shear stress, crack density and pore pressure govern the frequency-magnitude distribution. By investigating the frequency-magnitude distribution separately for preseismic and postseismic periods for the Morgan Hill mainshock, we find that only the volume in the vicinity of the highest slip release shows a significant increase in the b value, which decays to premainshock values within a year. Surrounding areas of the aftershock zone show an approximately constant b value with time. Because the aftershock hazard after a mainshock depends strongly on both the b and p value, we propose that aftershock hazard assessment can be improved by taking into account the spatial distribution of the parameters.

[1] We show fine-scale variations of seismic velocities and converted teleseismic waves that reveal the presence of zones of high-pressure fluids released by progressive metamorphic dehydration reactions in the subducting Philippine Sea plate in Tokai district, Japan. These zones have a strong correlation with the distribution of slow earthquakes, including long-term slow slip (LTSS) and low-frequency earthquakes (LFEs). Overpressured fluids in the LTSS region appear to be trapped within the oceanic crust by an impermeable cap rock in the fore-arc, and impede intraslab earthquakes therein. In contrast, fluid pressures are reduced in the LFE zone, which is deeper than the centroid of the LTSS, because there fluids are able to infiltrate into the narrow corner of the mantle wedge, leading to mantle serpentinization. The combination of fluids released from the subducting oceanic crust with heterogeneous fluid transport properties in the hanging wall generates variations of fluid pressures along the downgoing plate boundary, which in turn control the occurrence of slow earthquakes. Citation: Kato, A., et al. (2010), Variations of fluid pressure within the subducting oceanic crust and slow earthquakes, Geophys.

From a heat capacity (C p ) measurement on a single crystal sample of the S 1 quasi-onedimensional (Q1D) Heisenberg antiferromagnet (HAF) Ni͑C 5 H 14 N 2 ͒ 2 N 3 ͑PF 6 ͒ in applied magnetic fields, we found an anomaly which is indicative of a magnetic long-range ordering. We were able to follow how the position of the anomaly in C p changes with temperature ͑T͒ and magnetic field (H). An experimental H-T phase diagram of an S 1 Q1D HAF is obtained and compared with that of the corresponding classical system. [S0031-9007(98)07105-1] PACS numbers: 75.30. Kz, 75.10.Jm, 75.40.Cx, 75.50.Ee Although the theoretical study of one-dimensional (1D) magnetism began in the 1930s [1], several decades passed before suitable model compounds became available [2]. Quasi-1D magnets, in which the magnetic interaction in one direction dominates, with much weaker interactions in other directions, exhibit a short-range ordering over a wide temperature range and usually show a long-range ordering (LRO) at finite temperature due to the interchain coupling (J 0 ). The situation is largely altered in the case of quasi-1D Heisenberg antiferromagnet (HAF) with integer spin quantum number (S). As has been predicted by Haldane [3], there is an energy gap (Haldane gap) between the singlet ground state and first excited triplet in an S 1 1D HAF. The effects of J 0 on the Haldane gap have been studied theoretically [4,5] and the results show that the Haldane gap survives even at T 0 K, if J 0 is small [͑z 0 J 0 ͞J & 0.05͒ z 0 : number of adjacent chains; J: intrachain coupling]. Therefore, quasi-1D S 1 HAF compounds with small J 0 become nonmagnetic at low temperatures and no LRO occurs. On the other hand, strong magnetic fields destroy the Haldane gap and the system recovers magnetism [6]. Then, we expect a magnetic ordering to occur in a quasi-1D S 1 HAF under high fields and at low temperatures.The magnetic ordering in a quasi-1D classical HAF has been studied both theoretically [7,8] and experimentally [9,10]. These experiments showed that the Néel temperature (T N ) of the quasi-1D S 5͞2 HAF compound ͑CH 3 ͒ 4 NMnCl 3 (TMMC) which exists already in zero field increases with increasing field.In a previous paper [11], we reported experimental evidence for the field induced magnetic ordering in the S 1 quasi-1D HAF compound Ni͑C 5 H 14 N 2 ͒ 2 N 3 ͑ClO 4 ͒, abbreviated NDMAZ. From a heat capacity (C p ) measurement on a single crystal sample of NDMAZ, we observed an anomaly at about 0.6 K and at 12 T which indicated that a magnetic ordering occurred there. Because of limitations in our calorimeter, we were unable to follow how the position of the anomaly in C p changes with temperature ͑T ͒ and magnetic field (H). We then tried to synthesize a new quasi-1D HAF compound with a weaker intrachain exchange interaction in which an LRO is expected to be induced at a lower field. In this paper, we report the first experimental H-T phase diagram of a quasi-1D S 1 HAF which might be interesting to broad audiences. It is also interesting to compare t...

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