Tectonic Evolution of the Sambagawa Schists and its Implications in Convergent Margin Processes

The Sambagawa schists as high P /T metamorphic rocks are a member of Mesozoic accretionary complexes developed in the southern front of the Kurosegawa-Koryoke continent of Southwest Japan. The Mesozoic accretionary complexes are divided into four megaunits developed as nappes, Chichibu megaunit II, Sambagawa megaunit, Chichibu megaunit I and Shimanto megaunit in descending order of structural level. The Chichibu megaunit II consists of three accretionary units developed as nappes, late early Jurassic unit, late middle Jurassic unit and latest Jurassic unit (Mikabu unit) in descending order of structural level. The Chichibu megaunit I consists of five accretionary units developed as nappes, late middle Jurassic unit (Niyodo unit), late Jurassic unit, Valanginian unit, Barremian unit and Albian unit in descending order of structural level. The Shimanto megaunit, which just underlies the Chichibu megaunit I, is Cenomanian-Turonian accretionary unit and Coniacian-Campanian accretionary unit. The schists, which underlie the Chichibu megaunit II, all have been so far called the Sambagawa schists. These are divided into six units, Saruta unit, Fuyunose unit, Sogauchi unit, Sakamoto unit, Oboke unit and Tatsuyama unit in descending order of structural level, which show different tectono-metamorphic history and different radiometric ages from each other. The Sakamoto unit, Oboke unit and Tatsuyama unit have been assumed with reference to their radiometric ages and structural relations to belong to the late middle Jurassic accretionary unit of the Chichibu megaunit I (high pressure equivalent of the Niyodo unit), the Cenomanian-Turonian accretionary unit of the Shimanto megaunit and the Coniacian-Campanian accretionary unit of the Shimanto megaunit respectively in this paper. The upper member of the Sambagawa schists, Saruta unit, Fuyunose unit and Sogauchi unit, is therefore called the Sambagawa megaunit in this paper. The northern half and the southern half of the Sambagawa megaunit are intercalated as nappes between the Chichibu megaunit II and the Oboke unit and between the Chichibu megaunit II and the Sakamoto unit respectively. The constituent units of the Chichibu megaunit II, Sambagawa megaunit and Shimanto megaunit clearly show a downward younging age polarity, as compared with each other with reference to the oldest one of radiometric ages ( = metamorphic ages) of each unit. The Chichibu megaunit II and the Chichibu megaunit I show the same radiometric ages as compared between them with the same fossil age. The Saruta unit, Fuyunose unit and Sogauchi unit have therefore been assumed to be high pressure equivalent of Valanginian unit, that of Barremian unit and that of Albian unit of the Chichibu megaunit I respectively. These high pressure units were exhumed, separating the Chichibu supermegaunit into the Chichibu megaunit II and the Chichibu megaunit I and thrusting up onto the Chichibu megaunit I. On the basis of the growth history of amphibole in hematite-bearing basic schists of the Sambagawa megaunit, it has been assumed that the highest temperature metamorphism of the Fuyunose unit occurred, when it had been coupled with the Saruta unit which was exhuming, and that of the Sogauchi unit did through its coupling with the Fuyunose and Saruta units which were exhuming. In the subduction zone which was responsible for the formation of the Sambagawa megaunit, namely, the peak metamorphism of a newly subducted unit appears to have occurred when it had been coupled with previously subcreted units which were exhuming. It has been also clarified that the subduction of a new unit occurred mixing the lower pressure part of the pre-existing subcretion unit as tectonic blocks. There is a distinct difference in the oldest one of radiometric ages between constituent units of the Sambagawa schists, showing a downward younging age polarity. The oldest one of radiometric ages of each unit appears to approximate to the age of the ending of peak metamorphism and to the age (Eh age) of the beginning of its exhumation. Such the tectonics of the Sambagawa megaunit would be explained in term of two-way street model. Because the age (Sub age) of the beginning of the subduction of each unit can be assumed from its fossil age, the average velocity of the subduction and that of the exhumation of the Sambagawa megaunit in Shikoku have roughly been estimated to be ca. 0.9 mm/year and ca. 2.0 mm/year respectively. Deformation of quartz, whose style depends strongly upon strain rate, resulted in type I crossed girdle without conentration in Y even in the depth part of more than 10kb of the subduction zone, which was placed under temperature condition of much higher than 500°C, unlike the cases of magma-arcs where quartz c-axis fabrics with maximum concentration in Y are found in gneisses produced under temperature condition of lower than 500°C. Quartz deformation in the depth part of 15-17kb of the subduction zone appears to have occurred as dominant prism slip. The hanging wall of the Kurosegawa-Koryoke continent, which was placed at the depth of ca. 15-17 kb, thrust onto the Saruta unit at the depth of ca. 10-11 kb, accompanying intermingling of constituent rocks of the former and the latter and also mixing of various depth parts of the latter. The highest temperature metamorphism of the Saruta unit, which appears to have occurred under metamorphic condition of lower P /T than under that related to the formation of the general type of high P /T type metamorphic rocks, is ascribed to a contact metamorphism related to the overthrusting of the Kurosegawa-Koryoke continent. The thrusting of the Kurosegawa-Koryoke continent is ascribed to its collision with the Hida continent. The coupling of the previously subcreted Saruta unit with the newly subcreted Fuyunose unit occurred accompanying nearly isobaric cooling of the former. The great exhumation of the Saruta nappe (I + II) and Fuyunose nappe schists with great volume began together with the subcretion of the Sogauchi unit. The beginning age of the exhumation of the Sambagawa schists with great volume appears to coincide with that of the subduction of the Kula-Pacific ridge in Kyushu-Shikoku, which has been assumed by Kiminami et al. (1990). Namely, their great exhumation occurred with the progress of the subduction of the Kula-Pacific ridge with an eastward younging age polarity. The exhumation units, which were developed after the Mikabu unit, clearly show an eastward younging age polarity. Namely, these comparable with the Saruta unit, Fuyunose unit and Sogauchi unit are not found in central Japan and the Kanto Mountains. Rock deformation in the deformation related to the exhumation of the Sambagawa schists and their underlying schists appears to have commonly been of flattened type in mean strain. During the Ozu phase when the Kula-Pacific ridge subducted to the greater depth, the collapse of the Kurosegawa-Koryoke continent took again place, accompanying that of the pile nappe structures of the Sambagawa megaunit, Chichibu megaunit I and Oboke unit, and the thermal gradient along the plate boundary greatly changed, giving rise to medium P/T type metamorphism in the subduction zone (formation of the Tatsuyama nappe schists). The geological structures of the Sambagawa megaunit consist thus of two types of pile nappe structures, pre-Ozu phase pile nappe structures and Ozu phase pile nappe structures. The former is structures related to the coupling of the exhuming units ( = previously subcreted units) with the newly subcreted unit. The latter is structures showing the collapse of the former. The Ozu phase pile nappe structures are further divided into the pile nappe structures formed during the earlier stage (Tsuji stage) of the Ozu phase and these formed during the later stage (Futami stage). The former is disharmonic with reference to movement picture with the latter: The deformation related to the formation of the former, accompanying exhumation of the Oboke nappes, appears to contain a component of northward displacement, while that for the latter does a component of southward displacement. After the Ozu phase deformation the Sambagawa megaunit suffered the Hijikawa-Oboke phase folding, forming a series of sinistral en echelon upright folds. The relationship between the above-mentioned tectonic events of the Sambagawa megaunit and its surroundings and their radiometric ages is summarized as follows: [Original table is skipped. For more details, please refer to the full text.

Analysis of Signal Fading of Photostimulable Phosphor Plate System and Its Effect on the Accuracy in Detecting Proximal Caries

To clarify 1) how the signal fading effect occurs and 2) the diagnostic quality of the signal fading image in caries diagnosis. The Digora Optime (Soredex, Helsinki, Finland) system was used. Aluminum step wedges of 1 to 10 mm thickness and 1-mm-thick lead were used. Exposed photo-stimulated phosphor imaging plates (PSP-IPs) were scanned at six different intervals: immediately, 3, 6, 24, 72, and 144 h. Two kinds of scanning modes were used: with and without auto enhancement correction (AEC). The gray value difference between the immediate and delayed scanning images in the same objective area was calculated as the signal fading effect value (FEV). Thirty extracted upper premolar teeth (carious: 42 surfaces) were used. Immediate, 3, 24, and 72 h delayed scan images were created. Four observers assessed them. The Friedman test was used for statistical analysis and statistical significance was p<0. 05. Analysis of the without AEC image revealed that the signal fading had the same gray value change. This change was not related to the initial gray value. In the processing of AEC, the middle part of the gray value tended to be more enhanced. Significant differences in gray value changes were observed after 3 h, but no statistically significant difference was seen in the caries diagnosis. The area under the receiver operating characteristic (ROC) curve (Az) from immediate, 3, 24, and 72 h delayed images was 0. 61±0. 17, 0. 56±0. 04, 0. 67±0. 04, and 0. 58±0. 06

Precision Synthesis of Polylactide-Based Thermoresponsive Block Copolymers via Successive Living Cationic Polymerization of Vinyl Ether and Ring-Opening Polymerization of Lactide

A new class of polylactide (PLA)-based block copolymers with thermoresponsive poly(vinyl ether) [poly(VE)] were precisely synthesized via successive living cationic polymerization of VE and ring-opening polymerization of lactide (LA). The synthetic route starts with precise end-functionalization of poly(VE) by living cationic polymerization to produce a macroinitiator having a hydroxy group at the α- and/or -end for ring-opening polymerization of LA. End-functionalized polymers of 2-methoxyethyl VE (MOVE) with highly controlled structures were obtained by either an initiation or a termination method under optimized conditions. Subsequent ring-opening polymerization of LA from the hydroxy group of the macroinitiator yielded block copolymers with well-defined structures. The obtained block copolymers were demonstrated to exhibit a thermoresponsive solubility transition in water; this transition was induced by the thermosensitivity of the poly(MOVE) segments. The transition between micelle-like aggregates and phase separation was reversible with a shorter PLA chain, whereas irreversible precipitation was observed with a longer PLA segment. The permanent precipitation upon heating is most likely attributable to crystalline formation of the longer PLA segments. The solution and bulk properties of the block copolymers with enantiomeric PLA were also governed by stereocomplex formation between poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) segments

SV40 miR-S1 and Cellular miR-1266 Sequester Each Other from Their Targets, Enhancing Telomerase Activity and Viral Replication

Virus-encoded microRNAs (miRNAs) target viral and host mRNAs to repress protein production from viral and host genes, and regulate viral persistence, cell transformation, and evasion of the immune system. The present study demonstrated that simian virus 40 (SV40)-encoded miRNA miR-S1 targets a cellular miRNA miR-1266 to derepress their respective target proteins, namely, T antigens (Tags) and telomerase reverse transcriptase (TERT). An in silico search for cellular miRNAs to interact with viral miR-S1 yielded nine potential miRNAs, five of which, including miR-1266, were found to interact with miR-S1 in dual-luciferase tests employing reporter plasmids containing the miRNA sequences with miR-S1. Intracellular bindings of miR-1266 to miR-S1 were also verified by the pull-down assay. These miRNAs were recruited into the Ago2-associated RNA-induced silencing complex. Intracellular coexpression of miR-S1 with miR-1266 abrogated the downregulation of TERT and decrease in telomerase activity induced by miR-1266. These effects of miR-S1 were also observed in miR-1266-expressing A549 cells infected with SV40. Moreover, the infected cells contained more Tag, replicated more viral DNA, and released more viral particles than control A549 cells infected with SV40, indicating that miR-S1-induced Tag downregulation was antagonized by miR-1266. Collectively, the present results revealed an interplay of viral and cellular miRNAs to sequester each other from their respective targets. This is a novel mechanism for viruses to manipulate the expression of viral and cellular proteins, contributing to not only viral lytic and latent replication but also cell transformation observed in viral infectious diseases including oncogenesis

Physician-patient communication and patient satisfaction in Japanese cancer consultations

Over the past few decades, physician-patient communication has been intensively studied in western countries, because of its importance for the physician-patient relationship and patient health outcomes. Although various concepts and models of this relationship have recently been introduced in Japan, there are few studies on Japanese physician-patient interaction. The purpose of this study is to describe characteristics of physician-patient communication in a Japanese cancer consultation, and to examine the relation of this interaction with patient satisfaction. One hundred and forty cancer outpatients and twelve physicians were included. The Roter Interaction Analysis System (RIAS), one of the most frequently used systems for analyzing physician-patient interaction, was applied. Physicians made more utterances directing the interaction than patients did, and their discussion was largely focused on biomedical topics. It can be concluded that the structure of the physician-patient interaction in our study was basically similar to those in previous western studies, although some differences were also found. The relation between physician-patient communication and patient satisfaction was generally consistent with previous studies. Patients were more satisfied with consultations in which the physician used more open-ended questions. On the other hand, physician direction and encouragement was negatively associated with patient satisfaction. Also, patients who asked more questions were less satisfied with the consultation.Cancer consultation Japan Patient satisfaction Physician-patient communication

Prognostic Evaluation of Endodontic Retreatment —A Cone Beam Computed Tomography-based Study—

This retrospective study used cone beam computed tomography (CBCT) to evaluate various radiographic prognostic indicators that affect the outcome of root canal retreatment. The study population was selected from consecutive patients examined in the endodontic department from June 1 to December 31, 2013. In total, data were collected for 143 patients (mean age 47.7 years; female: 89, male: 44) who underwent CBCT examination, including 276 roots with periapical radiographs of 158 teeth. CBCT images were re-interpreted independently by one oral radiologist for cases of periapical root resorption and periapical hypercementosis. Nonsurgical endodontic retreatment was indicated for 125 roots, and was subsequently performed by one of four certified endodontists. Each case was followed up and the prognosis was assessed in October 2014. Of 125 root canal-treated cases, 96 were deemed to have a “satisfactory” prognosis, 27 were considered “questionable” and 2 were considered “unsatisfactory”. In the 96 “satisfactory” cases, 15 showed periapical hypercementosis, and 51 showed periapical root resorption. The chi-squared test was used to analyze differences between groups. A value of P<0.05 was considered significant. There was a significant difference in the prognosis between the hypercementosis cases and the other groups. Several studies suggest that the presence of root resorption may worsen the prognosis of endodontic treatment. In this study, the presence of root resorption did not affect prognosis. This study provides evidence that CBCT is helpful in evaluating the prognosis of endodontic retreatment cases

Precision Synthesis of Polylactide-Based Thermoresponsive Block Copolymers via Successive Living Cationic Polymerization of Vinyl Ether and Ring-Opening Polymerization of Lactide

A new class of polylactide (PLA)-based block copolymers with thermoresponsive poly­(vinyl ether) [poly­(VE)] were precisely synthesized via successive living cationic polymerization of VE and ring-opening polymerization of lactide (LA). The synthetic route starts with precise end-functionalization of poly­(VE) by living cationic polymerization to produce a macroinitiator having a hydroxy group at the α- and/or ω-end for ring-opening polymerization of LA. End-functionalized polymers of 2-methoxyethyl VE (MOVE) with highly controlled structures were obtained by either an initiation or a termination method under optimized conditions. Subsequent ring-opening polymerization of LA from the hydroxy group of the macroinitiator yielded block copolymers with well-defined structures. The obtained block copolymers were demonstrated to exhibit a thermoresponsive solubility transition in water; this transition was induced by the thermosensitivity of the poly­(MOVE) segments. The transition between micelle-like aggregates and phase separation was reversible with a shorter PLA chain, whereas irreversible precipitation was observed with a longer PLA segment. The permanent precipitation upon heating is most likely attributable to crystalline formation of the longer PLA segments. The solution and bulk properties of the block copolymers with enantiomeric PLA were also governed by stereocomplex formation between poly­(l-lactide) (PLLA) and poly­(d-lactide) (PDLA) segments

Management of Amniotic Sheet with a Hammock-like Placenta

An amniotic sheet is a septation in the amniotic cavity with a perforation that allows amniotic fluid to pass through. Although the incidence of abnormal placental implantation is higher in such cases, the management recommendations remain unclear. We report a case of an amniotic sheet with a hammock-like placenta located in the center of the uterine cavity. A 25-year-old woman with a history of two dilation and curettage procedures was found to have an amniotic cavity separated by a septum that contained part of the placenta. At gestational Week 32, magnetic resonance images revealed that the placenta was attached from the anterior to posterior uterine walls and resembled a hammock hanging in the center of the uterus. Subsequently, continuous intravenous administration of ritodrine hydrochloride and magnesium sulfate were given. The pregnancy was extended to Week 36. Elective cesarean section was performed, and a 3212-g female infant was delivered. Thus, owing to the risk of umbilical cord complications and placental injury secondary to premature rupture of membranes, aggressive and careful perinatal management is required in such cases