prior to surface appearance of sunspot flux tubes and magneto-thermal pulsation of the Sun

We found an evidence that the luminosity of the Sun systematically decreased about 20 days before sunspot surface appearance by analysing time-lag correlation of time derivatives of running mean time profiles of the data of the Active Cavity Radiometer Irradiance Monitor (ACRIM) I experiment on board of Solar Maximum Mission (SMM) and of the data of the daily sunspot number. This indicates that sunspot flux tube cooling and heat transport blocking by the flux tubes start to take place in the interior of the solar convection zone well before the sunspot surface appearance. From this finding and our previous finding that the luminosity of the Sun systematically increased and the blocked heat appeared on the surface about 50 days after the sunspot surface appearance, a new view of sunspot formation and dynamics and a new view of the luminosity modulation emerged. (i) Sunspots of a solar cycle are formed from clusters of flux tubes which can be seen in the running mean time profile of the sunspot number as a peak with duration on the order of 100 to 200 days. (ii) Heat flow is blocked by the cluster of sunspot flux tubes inside the convection zone to decrease the luminosity about 20 days before the surface emergence of the sunspot cluster. (iii) The blocked heat appears on the surface about 50 days after the surface emergence of the cluster of sunspot flux tubes to heat up the surface. This appears as a thermal pulse in the running mean time profile of the ACRIM dat in between the peaks of the sunspot running mean time profile. This process of heating the surface makes the temperature gradient less steep and weakens the buoyancy of sunspot flux tubes below the surface. (vi) The radiative cooling of the surface layer by the excess heat release steepens the temperature gradient so that the buoyancy of the sub-surface magnetic flux tubes becomes stronger to cause the next surge of emergence of a cluster of sunspots and other magnetic activities, which creates a peak in the time profile of the sunspot number. We call this peak a magnetic pulse of the Sun and the coupled process of alternating pulsed appearance of heat and sunspots the magneto-thermal pulsation of the Sun.     

A rate‐dependent constitutive model of high damping rubber bearings: modeling and experimental verification

In this study, a constitutive model of high damping rubber bearings (HDRBs) is developed that allows the accurate representation of the force–displacement relationship including rate‐dependence for shear deformation. The proposed constitutive model consists of two hyperelastic springs and a nonlinear dashpot element and expresses the finite deformation viscoelasticity laws based on the classical Zener model. The Fletcher–Gent effect, manifested as high horizontal stiffness at small strains and caused by the carbon fillers in HDRBs, is accurately expressed through an additional stiffness correction factor α in the novel strain energy function. Several material parameters are used to simulate the responses of high damping rubber at various strain levels, and a nonlinear viscosity coefficient η is introduced to characterize the rate‐dependent property. A parameter identification scheme is applied to the results of the multi‐step relaxation tests and the cyclic shear tests, and a three‐dimensional function of the nonlinear viscosity coefficient η with respect to the strain, and strain rate is thus obtained. Finally, to investigate the accuracy and feasibility of the proposed model for application to the seismic response assessment of bridges equipped with HDRBs, an improved real‐time hybrid simulation (RTHS) test system based on the velocity loading method is developed. A single‐column bridge was used as a test bed and HDRBs was physically tested. Comparing the numerical and RTHS results, advantage of the proposed model in the accuracy of the predicted seismic response over comparable hysteretic models is demonstrated. Copyright © 2016 John Wiley & Sons, Ltd.     

Kinetics of biotite dissolution and Fe behavior under low O2 conditions and their implications for Precambrian weathering

Biotite dissolution experiments were carried out to better understand the dissolution kinetics and Fe behavior under low O₂ conditions, and to give an insight into the Precambrian weathering. Mineral dissolution with a continuous flow-through reactor was employed at 25 °C for up to 65 days varying partial pressure of atmospheric oxygen (PO₂), pH (6.86 and 3.01) and Fe content in mineral (1.06 and 0.11 mol of Fe per O₁₀(OH,F)₂ for biotite and phlogopite, respectively) independently for the examination of their effects on biotite dissolution. Low PO₂ conditions were achieved in a newly developed glove box (PO₂ ? 6 × 10⁻⁴ atm; referred to as anoxic conditions), which was compared to the present, ambient air conditions (0.2 atm of PO₂; oxic conditions). The biotite dissolution rate was slightly faster under anoxic conditions at pH 6.86 while it was not affected by PO₂ at pH 3.01. There was no direct effect of Fe content on dissolution rate at pH 6.86 while there was a small difference in dissolution rate between biotite and phlogopite at pH 3.01. The 1.5 order-of-magnitude faster release rate of Fe under anoxic conditions for biotite dissolution at pH 6.86 resulted from the difference in ratio of Fe³⁺ precipitates remaining in the reactor to Fe dissolved (about 60% and 100% under anoxic and oxic conditions, respectively), which is caused mainly by the difference in PO₂. The results infer that the Fe²⁺ and Fe³⁺ contents in the Paleoproterozoic paleosols, fossil weathering profiles, are reflected by atmospheric oxygen levels at the time of weathering.     

Degradation and dissolution of zooplanktonic organic matter and lipids in early diagenesis

A degradation experiment with zooplankton was carried out to investigate the diagenesis of zooplanktonic organic matter, lipids, and lipid classes. In addition, reactivities and the quantitative relation between bulk organic carbon and waxes (which are the biomarkers of zooplankton) were compared during the experiment to evaluate the possibility of estimating the contributions of zooplanktonic organic matter in organic carbon pools, such as settling particles and surface sediments, from the wax concentration. Lipids were found to be more labile than the bulk organic carbon. Major parts of the organic carbon and lipids which remained on day 120 were found in the particulate fraction, and the accumulations of stable organic carbon and lipids in the dissolved fraction were limited. Although the lipids were more labile than the bulk organic carbon in the early phase of the experiment, the degradation rate of lipids obviously decreased in the subsequent degradation period, demonstrating the presence of stable lipids in zooplankton. Whereas triglycerides readily decreased, phospholipids persisted, making a major contribution to particulate lipids throughout the experiment. Waxes and other structural lipids such as glycolipids were also stably preserved in particulate lipids, suggesting that stable lipids in particulate matter are composed of structural lipids and waxes during early diagenesis. The degradation rate of waxes showed values comparable to that of bulk organic carbon after 11 days of degradation, resulting in constant ratios of waxes/bulk organic carbon (0.8 ± 0.2%, n = 7) during the later incubation period (after 11 days). This result suggests that the ratio could prove useful in evaluating the zooplanktonic organic carbon in organic carbon pools such as surface sediments and settling particulates.     

Oxygen and carbon isotope records of cultured freshwater pearl mussel <Emphasis Type="Italic">Hyriopsis</Emphasis> sp. shell from Lake Kasumigaura,Japan

We present oxygen and carbon isotope ratios and the morphological structure of the cultured freshwater pearl mussel (Hyriopsis sp., Unionidae) shell and pearl. The number of first-order fluctuations of δ¹⁸O of the outer shell layer along the maximum growth axis was consistent with the number of cultured years. The dominant factor controlling annual δ¹⁸O fluctuations was water temperature with a minor contribution from the variation in δ¹⁸O of ambient water, especially during the rainy season. The δ¹³C values were approximately constant throughout the life of the mussel, suggesting that the contributions of body size to δ¹³C of the shell were minor. We observed nine distinct disturbance rings on the outer surface of the shell. Five rings coincided with the five winter peaks of the δ¹⁸O profile, indicating winter growth cessation below approximately 10°C, probably because of either inactive growth at low water temperatures or reproduction. Summer disturbance rings were not observed in all years. Moreover, some summer rings showed discontinuity in the inner structure. These findings suggest that summer growth cessation may be caused by occasional events such as heavy rains, as the decrease of dissolved oxygen concentration. The δ¹⁸O profile and shell structures indicated that shell aragonite was precipitated at close to equilibrium conditions with respect to the oxygen isotope composition of the ambient water. Hyriopsis sp. shells can potentially be used for reconstruction of past hydrologic conditions. The δ¹⁸O of a pearl indicated that calcification occurred over a temperature range of at least 13–23°C. The optimal temperature for pearl calcification in this species is lower than that for marine pearl calcification.     

20th century seasonal moisture balance in Southeast Asian montane forests from tree cellulose δ18O

The seasonally varying moisture balance in a montane forest of Southeast Asia is reconstructed for the 20th century from the oxygen isotopic composition (δ¹⁸O) of subannual tree cellulose samples of Pinus kesiya growing at 1,500?m elevation on Doi Chiang Dao in northern Thailand. The cellulose δ¹⁸O values exhibit a distinctive annual cycle with amplitude of up to 12?‰, which we interpret to represent primarily the seasonal cycle of precipitation δ¹⁸O. The annual mean δ¹⁸O values correlate significantly with the amount of summer monsoon precipitation, and suggest a temporal weakening relationship between the South Asian monsoon and El Ni?o-Southern Oscillation over the late 20th century. The cellulose δ¹⁸O annual maxima values, which reflect the dry season moisture status, have declined progressively over the 20th century by about 3.5?‰. We interpret this to indicate a change in the contribution of the isotopically distinct fog water to the dry season soil moisture in response to rising temperature as well as deforestation.     

Winter precipitation isotope slopes of the contiguous USA and their relationship to the Pacific/North American (PNA) pattern

This study compares the synoptic-dynamic relationship between two phases of the Pacific/North American (PNA) pattern and winter precipitation isotopes at 73 sites across the contiguous USA. We use the spatial pattern of isotope slope—the rate of changes in precipitation isotope ratios with distance—to identify features in the seasonal precipitation isotope fields related to climatic patterns, PNA positive and PNA negative. Our results show relationships between zones of high isotope slopes and the spatial position of the polar jet stream and juxtaposition of air masses associated with the PNA pattern. During a positive PNA winter, zones of high isotope slope in the eastern USA shift southward. This change is coincident with a southward displacement of the polar jet stream in this region, which leads to a greater frequency of polar air masses and ¹⁸O-depleted isotope values of precipitation in the region. In the western USA, zones of high slope shift eastward during the positive PNA winter, associated with more frequent penetration of tropical air masses that bring ¹⁸O-enriched precipitation to the region. Differences in δ¹⁸O/temperature relationships between the PNA-positive and -negative winters and contrasting δ¹⁸O/temperature behaviors in the eastern and western USA provide support for the role of variation in moisture source and transport as a control on the isotopic patterns. These findings highlight the importance of synoptic climate driven by PNA pattern in determining the spatial patterns of precipitation isotopes and provide constraints on paleo-water isotope interpretation and modern isotope hydrological processes.     

Two timescales in beach erosion due to decrease in sediment sources with special reference to the formation and reduction of the delta of the Kurobe River flowing into the Japan sea

Beach erosion has advanced in many countries of the world, especially in Japan, because of a decrease in sediment sources from rivers and a lack of longshore sediment transport from the adjacent coasts due to coastal structures. The former cause concerns the reduction of river deltas due to a decrease in sediment input from the river. Two timescales important in beach erosion, a longer timescale which concerns a change in the location of the river mouth, and a shorter one which is due to a decrease in longshore sediment transport, are discussed in the formation and reduction of the delta of the Kurobe River. Based on these timescales, beach erosion control is considered.     

Energetics and Dynamics of an Impulsive Flare on March 10, 2001

We present Hα observations from ARIES (Nainital) of a compact and impulsive solar flare that occurred on March 10, 2001 and which was associated with a CME. We have also analyzed HXT, SXT/Yohkoh observations as well as radio observations from the Nobeyama Radio Observatory to derive the energetics and dynamics of this impulsive flare. We coalign the Hα, SXR, HXR, MW, and magnetogram images within the instrumental spatial-resolution limit. We detect a single HXR source in this flare, which is found spatially associated with one of the Hα bright kernels. The unusual feature of HXR and Hα sources, observed for the first time, is the rotation during the impulsive phase in a clockwise direction. We propose that the rotation may be due to asymmetric progress of the magnetic reconnection site or may be due to the change of the peak point of the electric field. In MW emission we found two sources. The main source is at the main flare site and another is in the southwest direction. It appears that the remote source is formed by the impact of accelerated energetic electrons from the main flare site. From the spatial correlation of multiwavelength images of the different sources, we conclude that this flare has a three-legged structure.     

Effect of variation of normal force on seismic performance of resilient sliding isolation systems in highway bridges

In this study, a series of shaking table tests are carried out on scaled models of two seismically isolated highway bridges to investigate the effect of rocking motion and vertical acceleration on seismic performance of resilient sliding isolators. In addition, performance of RSI is compared with system having solely natural rubber bearings. Test results show that variation of normal force on sliders due to rocking effect and vertical acceleration makes no significant difference in response of RSI systems. In addition, analytical response of prototype isolated bridge and the model used in experiments is obtained analytically by using non‐linear model for isolation systems. It is observed that for seismically isolated bridges, dynamic response of full‐scale complex structures can be predicted with acceptable accuracy by experiments using a simple model of the structure. Copyright © 2005 John Wiley & Sons, Ltd.