Gauss-Bonnet Chameleon Mechanism of Dark Energy

As a model of the current accelerated expansion of the universe, we consider a model of the scalar-Einstein-Gauss-Bonnet gravity. This model includes the propagating scalar modes, which might give a large correction to the Newton law. In order to avoid this problem, we propose an extension of the Chameleon mechanism where the scalar mode becomes massive due to the coupling with the Gauss-Bonnet term. Since the Gauss-Bonnet invariant does not vanish near the earth or in the Solar System, even in the vacuum, the scalar mode is massive even in the vacuum and the correction to the Newton law could be small. We also discuss about the possibility that the model could describe simultaneously the inflation in the early universe, in addition to the current accelerated expansion.Comment: LaTeX 11 pages, no figur

Stability of accelerating cosmology in two scalar-tensor theory: Little Rip versus de Sitter

We develop the general reconstruction scheme in two scalar model. The quintom-like theory which may describe (different) non-singular Little Rip or de Sitter cosmology is reconstructed. (In)stability of such dark energy cosmologies as well as the flow to fixed points is studied. The stability of Little Rip universe which leads to dissolution of bound objects sometime in future indicates that no classical transition to de Sitter space occurs.Comment: LaTeX 27 pages, 12 figures, version appeared in Entrop

Isolating along-strike variations in the depth extent of shallow creep and fault locking on the northern Great Sumatran Fault

The Great Sumatran Fault system in Indonesia is a major right-lateral trench-parallel system that can be divided into several segments, most of which have ruptured within the last century. This study focuses on the northern portion of the fault system which contains a 200-km-long segment that has not experienced a major earthquake in at least 170 years. In 2005, we established the Aceh GPS Network for the Sumatran Fault System (AGNeSS) across this segment. AGNeSS observes large displacements which include significant postseismic deformation from recent large megathrust earthquakes as well as interseismic deformation due to continued elastic loading of both the megathrust and the strike slip system. We parameterize the displacements due to afterslip on the megathrust using a model based on a rate- and state-dependent friction formalism. Using this approach, we are able to separate afterslip from other contributions. We remove predicted deformation due to afterslip from the observations, and use these corrected time series to infer the depth of shallow aseismic creep and deeper locked segments for the Great Sumatran Fault. In the northern portion of this fault segment, we infer aseismic creep down to 7.3 ± 4.8 km depth at a rate of 2.0 ± 0.6 cm/year. In the southwestern portion of the segment, we estimate a locking depth of 14.8 ± 3.4 km with a downdip slip rate of 1.6 ± 0.6 cm/year. This portion of the fault is capable of producing a magnitude 7.0 earthquake

Observation of GNSS scintillation in Tromsø

第3回極域科学シンポジウム/第36回極域宙空圏シンポジウム 11月26日（月）、27日（火） 国立極地研究所 2階ラウン

Study and Search for Main Reason of Lung Cancers Based on Cherenkov Radiation in Environmental Radiation

The number of lung-cancer-related death is highest among all cancers in the world, and it is increasing in Japan where population aging in progressing. The main reason for the lung cancer of non-smokers is regarded to be environmental pollution or exposure of the lung to radon in the nature. The risk of lung cancer was estimated to increase by 8 to 13% per every 100 Bq m-3 concentration of radon in the air. We observed beta rays with maximum energy of 3.27 MeV emitted from 214Bi as one of the progenies based on a detection of Cherenkov radiation. The surface radioactivity concentration of 214Bi on the sample was measured; the relation between the concentration and exposure time for the sample at the room air is researched. The behavior of the radon progenies in the air is discussed by a research for the progenies attaching on the sample after the radon decay. The inhalation of the radon progenies is not clear. Thus, to understand the behavior of progenies in the air make to clear the causal relation between the radon concentration and lung cancers

Effects of monthly intravenous ibandronate on bone mineral density and microstructure in patients with primary osteoporosis after teriparatide treatment: The MONUMENT study

Purpose: To investigate the effects of sequential therapy with monthly intravenous ibandronate on bone mineral density (BMD) and microstructure in patients with primary osteoporosis who received teriparatide treatment. Methods: Sixty-six patients with primary osteoporosis who had undergone teriparatide treatment for more than 12 months (mean 18.6 months) received sequential therapy with 1 mg/month intravenous ibandronate for 12 months. The patients were evaluated using dual-energy X-ray absorptiometry (DXA), quantitative ultrasound, bone turnover markers, and high-resolution peripheral quantitative computed tomography (HR-pQCT) at baseline and 6 and 12 months after beginning administration. Results: At 12 months after beginning sequential therapy,the bone resorption marker, tartrate-resistant acid phosphatase-5b, decreased by 39.5%, with 82.3% of the patients exhibiting levels within the normal limit. DXA revealed that the BMD of the lumbar spine increased by 3.2%, with 79.0% of the patients exhibiting a response, and 40.3% experiencing an increase in BMD over 5%. HR-pQCT revealed that the cortical thickness of the distal tibia was increased by 2.6%. The cortical area increased by 2.5%, and the buckling ratio (an index of cortical instability) decreased by 2.5%. Most parameters of the trabecular bone showed no significant changes. These changes in the cortical bone were observed in both the distal radius and tibia and appeared beginning 6 months after treatment initiation. Conclusions: Sequential therapy with monthly intravenous ibandronate increased the BMD and improved the cortical bone microstructure of osteoporotic patients who had undergone teriparatide treatment

A Tunable Wideband Frequency Synthesizer Using LC-VCO and Mixer for Reconfigurable Radio Transceivers

This paper proposes a novel wideband LC-based voltage-controlled oscillator (VCO) for multistandard transceivers. The proposed VCO has a core LC-VCO and a tuning-range extension circuit, which consists of switches, a mixer, dividers, and variable gain combiners with a spurious rejection technique. The experimental results exhibit 0.98 to 6.6 GHz continuous frequency tuning with −206 dBc/Hz of FoMT, which is fabricated by using a 0.18 μm CMOS process. The frequency tuning range (FTR) is 149%, and the chip area is 800 μm × 540 μm