Episodic tremor and slip on the Cascadia subduction zone: the chatter of silent slip

We found that repeated slow slip events observed on the deeper interface of the northern Cascadia subduction zone, which were at first thought to be silent, have unique nonearthquake seismic signatures. Tremorlike seismic signals were found to correlate temporally and spatially with slip events identified from crustal motion data spanning the past 6 years. During the period between slips, tremor activity is minor or nonexistent. We call this associated tremor and slip phenomenon episodic tremor and slip (ETS) and propose that ETS activity can be used as a real-time indicator of stress loading of the Cascadia megathrust earthquake zone.     

A silent slip event on the deeper Cascadia subduction interface

Continuous Global Positioning System sites in southwestern British Columbia, Canada, and northwestern Washington state, USA, have been moving landward as a result of the locked state of the Cascadia subduction fault offshore. In the summer of 1999, a cluster of seven sites briefly reversed their direction of motion. No seismicity was associated with this event. The sudden displacements are best explained by approximately 2 centimeters of aseismic slip over a 50-kilometer-by-300-kilometer area on the subduction interface downdip from the seismogenic zone, a rupture equivalent to an earthquake of moment magnitude 6.7. This provides evidence that slip of the hotter, plastic part of the subduction interface, and hence stress loading of the megathrust earthquake zone, can occur in discrete pulses.     

Slow earthquakes linked along dip in the Nankai subduction zone

We identified a strong temporal correlation between three distinct types of slow earthquakes distributed over 100 kilometers along the dip of the subducting oceanic plate at the western margin of the Nankai megathrust rupture zone, southwest Japan. In 2003 and 2010, shallow very-low-frequency earthquakes near the Nankai trough as well as nonvolcanic tremor at depths of 30 to 40 kilometers were triggered by the acceleration of a long-term slow slip event in between. This correlation suggests that the slow slip might extend along-dip between the source areas of deeper and shallower slow earthquakes and thus could modulate the stress buildup on the adjacent megathrust rupture zone.     

高温冻土中孔隙水压力量测初探

采用2种室内压缩试验方法研究高温冻土在变温变载条件下孔隙水压力的变化规律,即通过恒载变温试验和恒温变载试验分别从升温和加载的角度考虑高温冻土中孔隙水压力的变化,分析了孔隙水压力与温度变化及加载的关系.结果表明:高温冻土中孔隙水压力变化对荷载较为敏感,温度决定了孔隙水压力变化的实效性,在温度越高的条件下,孔隙水压力对加载...     

沿淮花生田蛴螬发生特点、原因分析与综防对策

通过10年来对我县花生田蛴螬发生情况的调查,论述了我县花生田的发生特点,分析了发生的原因,提出了以农业防治为基础,以化防为主,辅以其他措施的综防对策。     

高掺量粉煤灰混凝土的也隙液相碱度与护筋性

当混凝土的也隙液相碱度降低到１１．５以下时，钢筋纯化膜遭到破坏。试验表明，与普通混凝土相比，高掺量粉煤灰混凝土长龄期孔隙液相碱度出现了明显的降低，其护筋性更应该重视长龄期孔隙液相碱度。     

Extremely long-lived nuclear pore proteins in the rat brain

To combat the functional decline of the proteome, cells use the process of protein turnover to replace potentially impaired polypeptides with new functional copies. We found that extremely long-lived proteins (ELLPs) did not turn over in postmitotic cells of the rat central nervous system. These ELLPs were associated with chromatin and the nuclear pore complex, the central transport channels that mediate all molecular trafficking in and out of the nucleus. The longevity of these proteins would be expected to expose them to potentially harmful metabolites, putting them at risk of accumulating damage over extended periods of time. Thus, it is possible that failure to maintain proper levels and functional integrity of ELLPs in nonproliferative cells might contribute to age-related deterioration in cell and tissue function.     

Deformation and slip along the Sunda megathrust in the great 2005 Nias-Simeulue earthquake

Seismic rupture produced spectacular tectonic deformation above a 400-kilometer strip of the Sunda megathrust, offshore northern Sumatra, in March 2005. Measurements from coral microatolls and Global Positioning System stations reveal trench-parallel belts of uplift up to 3 meters high on the outer-arc islands above the rupture and a 1-meter-deep subsidence trough farther from the trench. Surface deformation reflects more than 11 meters of fault slip under the islands and a pronounced lessening of slip trenchward. A saddle in megathrust slip separates the northwestern edge of the 2005 rupture from the great 2004 Sumatra-Andaman rupture. The southeastern edge abuts a predominantly aseismic section of the megathrust near the equator.     

Variations in strength and slip rate along the san andreas fault system

Convergence across the San Andreas fault (SAF) system is partitioned between strike-slip motion on the vertical SAF and oblique-slip motion on parallel dip-slip faults, as illustrated by the recent magnitude M(s) = 6.0 Palm Springs, M(s) = 6.7 Coalinga, and M(s) = 7.1 Loma Prieta earthquakes. If the partitioning of slip minimizes the work done against friction, the direction of slip during these recent earthquakes depends primarily on fault dip and indicates that the normal stress coefficient and frictional coefficient (micro) vary among the faults. Additionally, accounting for the active dip-slip faults reduces estimates of fault slip rates along the vertical trace of the SAF by about 50 percent in the Loma Prieta and 100 percent in the North Palm Springs segments.     

A "silent" polymorphism in the MDR1 gene changes substrate specificity

Synonymous single-nucleotide polymorphisms (SNPs) do not produce altered coding sequences, and therefore they are not expected to change the function of the protein in which they occur. We report that a synonymous SNP in the Multidrug Resistance 1 (MDR1) gene, part of a haplotype previously linked to altered function of the MDR1 gene product P-glycoprotein (P-gp), nonetheless results in P-gp with altered drug and inhibitor interactions. Similar mRNA and protein levels, but altered conformations, were found for wild-type and polymorphic P-gp. We hypothesize that the presence of a rare codon, marked by the synonymous polymorphism, affects the timing of cotranslational folding and insertion of P-gp into the membrane, thereby altering the structure of substrate and inhibitor interaction sites.     

华北低槽控制下安徽省对流云特征统计分析

收集20012、002年5~10月华北低槽控制下安徽省对流云个例,通过分析卫星云图上对流云发生发展过程中云顶亮温、面积、几何形态等特征物理量的变化,来揭示这一天气背景下安徽省的对流云演变特征。结果表明,在华北低槽控制下,对流云发展过程中最低亮度温度一般在213~263 K;红外分裂窗亮温差和红外通道最低亮温值保持着较好的同步变化关系;面积分布上呈现出2高2低的特征;生命期存在1个界限时间区域,界限时间的取值区域与地域息息相关,这方面还有待于更深入的研究。     

Fusion pore dynamics and insulin granule exocytosis in the pancreatic islet

Insulin secretion from intact mouse pancreatic islets was investigated with two-photon excitation imaging. Insulin granule exocytosis occurred mainly toward the interstitial space, away from blood vessels. The fusion pore was unusually stable with a lifetime of 1.8 seconds. Opening of the 1.4-nanometer-diameter pore was preceded by unrestricted lateral diffusion of lipids along the inner wall of the pore, supporting the idea that this structure is composed of membrane lipids. When the pore dilated to 12 nanometers, the granules rapidly flattened and discharged their contents. Thus, our methodology reveals fusion pore dynamics in intact tissues at nanometer resolution.     

Advection of pore fluids through sediments in the equatorial East pacific

Measurements of the ratio of helium-4 to helium-3 and of calcium ion in the pore waters of sediments at two locations in the eastern equatorial Pacific indicate that solution advection is occurring through the sediments. Both the helium ratio and the calcium ion profile yield velocity values for advective flow of about 20 centimeters per year. Mass balance constraints are also consistent with the interpretation presented. Flow appears to be occurring thorugh relatively thick sediments, on the order of 300 meters.     

Detection and monitoring of ongoing aseismic slip in the Tokai region,central Japan

Analysis of global positioning system data shows that the rate of crustal deformations in the Tokai region of Japan, a seismic gap area, changed over the past 18 months. Kalman filtering analysis shows aseismic slip on the plate boundary in the western Tokai region centered on Lake Hamana, adjacent to the anticipated Tokai earthquake source area. The cumulative moment magnitude reaches 6.7 in June 2002 with a relative slip increase northeast of Lake Haman from January 2002. An existence of aseismic slip in the western Tokai supports the hypothesis of a silent event as the cause of uplifting several days before the 1944 Tonankai earthquake.     

唐代音乐兴盛的原由

唐朝政治稳定、经济繁荣,音乐也达到了前所未有的繁荣程度。本文从政治、经济文化交流、音乐机构设立、记谱法改革等方面揭示唐朝音乐兴盛的原由。