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Additional file 1. Site information (Table S1) and figures for the time series data observed by the OBEMs at NS02, NS03, NS05, and NS06 (Figures S1-S4).

Additional file 2. Magnetic source analysis using the horizontal and vertical field component anomalies and the results (Figures S5 and S6).

Additional file 4: Figure S3. Sounding curves of the scalar MT responses (Z det) and their averages in the four study areas.

Additional file 2: Figure S2. Synthetic inversion tests.

Additional file 1: Figure S1. MT responses for all sites in Area A and Area B.

International audience; We have conducted a seafloor magnetotelluric survey that images, for the first time, three-dimensional electrical conductivity structure in the upper mantle beneath the Society hotspot. A striking feature in our model is a high-conductivity anomaly a few hundred kilometers in diameter, which is continuous from the lowest part of the upper mantle to a depth of approximately 50 km below sea level. Using theoretical and experimental results from mineral physics, we interpret the high-conductivity anomaly as evidence of the melt fraction up to 2.2 vol.%, which is robust regardless of assumed temperature, and the existence of carbonated silicate melt beneath the hotspot. Our results suggest that the Society hotspot is a pathway for ascending volatiles from the deeper part of the upper mantle to the surface.

Tristan da Cunha Island is one of the classical hot spots in the Atlantic Ocean, situated at the western end of the aseismicWalvis Ridge which forms a connection to the Cretaceous Etendeka flood basalt province in northwestern Namibia. The discussion about its source (in shallow asthenosphere or deeper mantle) have not reached consensus yet because of lack of the geophysical observations in the area. A marine magnetotelluric (MT) experiment was conducted together with seismological observations in the area in 2012–2013 through a German-Japanese collaboration with the goal to constrain the physical state of the mantle beneath the area. A total of 26 MT seafloor stations were deployed around the Tristan da Cunha Islands and available data were retrieved and processed from 24 stations. We applied iterative topographic effect correction and one-dimensional (1-D) conductivity structure inversion to the data. Then, three-dimensional (3-D) inversion analysis incorporating the topographic effect was carried out, using the 1-D model as the initial model. The local small-scale topography and the far continental coast effects are incorporated as the distortion term in the 3-D inversion. The preliminary result of our analysis shows no evidence of a significant conductive anomaly arising from the mantle transition zone, suggesting that the current magmatic source (major place of melting) of the hotspot activity is in the shallow upper mantle. This is in contrast to results from geochemical analysis, in which samples along the Tristan track exhibit an ocean-island-basalt-type incompatible element pattern pointing to a deep mantle source of the melt. Our findings therefore might indicate that the deep mantle up-welling underneath Tristan da Cunha Islands may be almost dead. A conductive anomaly at approx. 100 km depth in our derived conductivity model to the southwest of Tristan da Cunha Islands suggests an interaction between the mid-ocean ridge and/or up-welling further south, e.g., beneath the Gough Island, which is the other termination of the Walvis Ridge and shows clearer geochemical evidence for a plume source.

According to classical plume theory, the Tristan da Cunha hotspot is thought to have played a major role in the rifting of the South Atlantic margins and the creation of the aseismic Walvis Ridge by impinging at the base of the continental lithosphere shortly before or during the breakup of the South Atlantic margins. However, Tristan da Cunha is enigmatic as it cannot be clearly identified as a hot spot but may also be classified as a more shallow type of anomaly that may actually have been caused by the opening of the South Atlantic. The equivocal character of Tristan da Cunha is largely due to a lack of geophysical and petrological data in this region. We therefore staged a multi-disciplinary geophysical study of the region by acquiring passive marine electromagnetic and seismic data, and bathymetric data within the framework of the SPP1375 South Atlantic Margin Processes and Links with onshore Evolution (SAMPLE) funded by the German Science foundation. The experiment included two ship expeditions onboard the German R/V MARIA S. MERIAN in 2012 and 2013. In our contribution we will present first results on the shear wave velocity structure of the lithosphere-asthenosphere system. We applied the classical two-station method; Rayleigh wave dispersion curves are determined by crosscorrelation of seismograms from a pair of station. We measured interstation phase velocities of (earthquakeexcited) fundamental-mode surface waves in a period range of 10 to 60 s. The selection of acceptable phasevelocity measurements in the frequency domain had to be done manually for each event.We present phase-velocity maps for the study area. Furthermore, we present 1D shear wave velocity models inverted from the highest-quality observations.

The Tristan da Cunha (TDC) Islands is one of the hotspots in the Atlantic Ocean. The discussion whether its magmatic source is deep in the mantle or in the shallower asthenospheric mantle have not reached consensus yet because of lack of the geophysical observations in the area. The electrical conductivity structure of the upper mantle beneath the area was investigated in this study to provide an answer to this question. Marine magnetotelluric data were collected from 26 sites in 2012–2013. Three-dimensional inversion analysis depicted a high conductive layer at �120 km depth but no plume like vertical structure. The conductive layer is mostly flat independently on seafloor age and bulges upward beneath the older lithospheric segment where the TDC Islands are located compared to younger segment south of the TDC Fracture Zone. Bathymetric data on the other hand shows that the northern segment is deeper than prediction for a one-dimensional cooling model suggests. This bathymetric anomaly coincides with a more conductive asthenospheric mantle north of the TDC Fracture Zone. Apparent inconsistency between the absence of vertical structure in this study and geochemical evidences on deep origin materials suggests that either the upwelling is too small and/or weak to be resolved by the current data set or that the upwelling takes place elsewhere outside of the study area. Other observations suggest that 1) the conductivity of the upper mantle can be explained by the fact that the mantle above the high conductivity layer is depleted in volatiles as the result of partial melting beneath the spreading ridge, 2) the potential temperature of the segments north of the TDC Fracture Zone is lower than that of the southern segment at least during the past �30 Ma.

According to classical plume theory, the Tristan da Cunha hotspot is thought to have played a major role in the rifting of the South Atlantic margins and the creation of the aseismic Walvis Ridge by impinging at the base of the continental lithosphere shortly before or during the breakup of the South Atlantic margins. However, Tristan da Cunha is enigmatic as it cannot be clearly identified as a hot spot but may also be classified as a more shallow type of anomaly that may actually have been caused by the opening of the South Atlantic. The equivocal character of Tristan da Cunha is largely due to a lack of geophysical and petrological data in this region. We therefore staged a multi-disciplinary geophysical study of the region by acquiring passive marine electromagnetic and seismic data, and bathymetric data within the framework of the SPP1375 South Atlantic Margin Processes and Links with onshore Evolution (SAMPLE) funded by the German Science foundation. The experiment included two ship expeditions onboard the German R/V MARIA S. MERIAN in 2012 and 2013. In our contribution we will present results on the thickness of the oceanic crust in the vicinity of the Tristan da Cunha archipelago derived from ocean-bottom seismometer data. Using the Ps receiver function method we estimate a thickness of 5 to 7 km for the oceanic crust at 17 ocean-bottom stations surrounding the islands in an area where the ocean floor has an age of approximately 10 to 30 Ma (from west to east). This indicates normal to slightly lowered magmatic activity at the mid-ocean ridge during the crust formation. There seems to be no major contribution of a mantle plume to the melting conditions at the ridge, which should cause the formation of thickened oceanic crust. The magmatic activity at the archipelago and surrounding seamounts seems to have only local effects on the crustal thickness. Furthermore, we imaged the mantle transition zone discontinuities analysing receiver functions at the permanent seismological station TRIS on Tristan da Cunha. Our observations show evidence for a thickened and therefore cold mantle transition zone in the northwest of the islands which excludes a deep-reaching mantle plume at this position. To the south of the island we have indications for a thinned and therefore hot mantle transition zone from sparse and noisy observations which could hint to the location of a mantle plume at mid-mantle depths.

According to classical plume theory, the Tristan da Cunha hotspot is thought to have played a major role in the rifting of the South Atlantic margins and the creation of the aseismic Walvis Ridge by impinging at the base of the continental lithosphere shortly before or during the breakup of the South Atlantic margins. But Tristan da Cunha is enigmatic, as it cannot be clearly identified as a hot-spot but classifies also highly as a more shallow type of anomaly that may actually have been caused by the opening of the South Atlantic. The equivocal character of Tristan is largely due to lack of geophysical data in this region. To understand the tectonic processes of the opening of the South Atlantic, the formation of the Walvis ridge and to understand whether Tristan da Cunha is the cause or the consequence of rifting, it is of central importance to characterize the region around Tristan da Cunha in a more coherent way. Within this research cruise we deployed 26 ocean bottom electromagnetic stations (OEBM) and 24 ocean bottom seismometer (OBS) for a long term acquisition (1 year) of magnetotelluric and seismological data, acquired bathymetry and gravity data and performed geological sampling on Tristan da Cunha. The data will be interpreted in the context of geochemical data and tectonic models developed within the SPP1375 South Atlantic Margin Processes and Links with onshore Evolution (SAMPLE)., MARIA S. MERIAN-Berichte

Let R be a Noetherian domain and α an anti-integral element of degree t over R. Let a, b, c and d be elements of R such that ad-be is a unit of R and aα-b is not zero. Set β = (cα-d)/(aα-b). In this paper, we prove that β is also an anti-integral element of degree t over R and J_=J_. By making use of J_=J_, we prove that R[α]/R is a flat extension if and only if so is R[β]/R. Furthermore, we investigate a generalized denominator ideal I_.

[CRUISE REPORT] This document is a preliminary report of YK08-09 on S/V YOKOSUKA from 2008-07-27 to 2008-08-18.

[CRUISE REPORT] This document is a preliminary report of KR07-06 on R/V KAIREI from 2007-05-06 to 2007-05-29.

The examinations of sera for HBV markers and the liver function tests were carried out on 343 inhabitants (29% of the whole population) in Aguni Village, Okinawa. The RPHA technique was used for determination of HBsAg and the PHA for HBsAb. HBsAg was found in 3.8% of examinees and HBsAb in 37%. Further studies by usig the Enzyme immunoassay for HBeAg and HBeAb and the determination of subtype by Radioimmunoassay were performed on HBsAg positive sera. Two HBeAg positive cases and 10 HBeAb positive were found among them and all cases belonged to the subtype adw. Two cases with HBeAg showed abnormal results of the liver function tests such as elevated value of s-GOT (≧40KU/ml) and/or s-GPT (≧35KU/ml), while no abnormal findings in 10 cases with HBeAb. It was been noticed that there was a remarkable difference of the results of the liver function tests between the HBsAg positive bnd negative groups; the former showed abnormal value in 23% and latter only in 1.8%.

The examinations of sera for HBV markers and the liver function tests were carried out on 343 inhabitants (29% of the whole population) in Aguni Village, Okinawa. The RPHA technique was used for determination of HBsAg and the PHA for HBsAb. HBsAg was found in 3.8% of examinees and HBsAb in 37%. Further studies by usig the Enzyme immunoassay for HBeAg and HBeAb and the determination of subtype by Radioimmunoassay were performed on HBsAg positive sera. Two HBeAg positive cases and 10 HBeAb positive were found among them and all cases belonged to the subtype adw. Two cases with HBeAg showed abnormal results of the liver function tests such as elevated value of s-GOT (≧40KU/ml) and/or s-GPT (≧35KU/ml), while no abnormal findings in 10 cases with HBeAb. It was been noticed that there was a remarkable difference of the results of the liver function tests between the HBsAg positive bnd negative groups; the former showed abnormal value in 23% and latter only in 1.8%., 論文

The examination of sera for HBs antigen and HBs antibody were carried out on 2,222 inhabitants in four village (Yonashiro, Minamidaito, Aguni, Tokashiki), Okinawa on 1983. HBs antigen was found in 3.7% among all examinees, and the higher positive rate was seen in the age groups 20-29 and 30-39. The positive rate of HBs antibody presented 36% totally, revealing higher rate with aging. And there was remarkable difference of the positive rate of HBs antibody between the age groups of less than 30 years old and that of over than 30 years. In the serological investigation for HBe antigen and HBe antibody on 81 asymptomatic HBs antigen carriers, HBe antigen was positive in 6 cases (7.4%) and HBe antibody in 69 cases (85%), respectively, It was noticed that among 68 HBV carriers of the age group over than 30 years old only two cases were HBe antigen positive. Among 185 HBs antigen positive sera obtained in this study, their antigen classified into two subtypes, adr and adw, the former 47 (25%) and the latter 138 (75%)., 論文

The major polypeptides composing hepatitis B surface antigen (HBsAg) particles are P-I and P-II. P-II shares the same amino acid sequence as P-I and contains an additional carbohydrate moiety of mol. wt approximately 5000. When a purified preparation of P-II was digested with Nagarse and then with Pronase P, it gave rise to a glycopeptide containing 15 amino acid residues and the carbohydrate moiety of P-II. The N -terminal amino acid sequence of the glycopeptide was determined to be Lys-Pro-Thr-Asp-Gly-Asn-. The polysaccharide moiety contained 5 moles of N -acetylglucosamine and was connected with Asn at the sixth position from the N -terminus. When mice were immunized against this HBsAg glycopeptide, they raised humoral antibodies which bound to each of three preparations of P-I derived from HBsAg particles of subtypes adw, adr and ayw , thereby indicating that the sequence of 15 amino acids in the glycopeptide would constitute a common antigenic structure of HBsAg.

The examination of sera for HBs antigen and HBs antibody were carried out on 2,222 inhabitants in four village (Yonashiro, Minamidaito, Aguni, Tokashiki), Okinawa on 1983. HBs antigen was found in 3.7% among all examinees, and the higher positive rate was seen in the age groups 20-29 and 30-39. The positive rate of HBs antibody presented 36% totally, revealing higher rate with aging. And there was remarkable difference of the positive rate of HBs antibody between the age groups of less than 30 years old and that of over than 30 years. In the serological investigation for HBe antigen and HBe antibody on 81 asymptomatic HBs antigen carriers, HBe antigen was positive in 6 cases (7.4%) and HBe antibody in 69 cases (85%), respectively, It was noticed that among 68 HBV carriers of the age group over than 30 years old only two cases were HBe antigen positive. Among 185 HBs antigen positive sera obtained in this study, their antigen classified into two subtypes, adr and adw, the former 47 (25%) and the latter 138 (75%).