[1] A discrete element model was developed to simulate the micromechanics of compaction localization in a granular rock. The rock was modeled as a bonded assembly of circular disks, and seven different distributions of radius were considered. To simulate grain crushing and pore collapse, an intragranular damage mechanism was introduced that allows for the shrinkage of a disk if one of its normal contact stresses attains a critical value. The model captures key attributes of failure mode and damage evolution associated with the brittle-ductile transition in porous sandstones. Our simulations indicate that the development of discrete compaction bands is promoted in a relatively homogeneous granular aggregate, while diffuse band growth and distributed cataclastic flow are preferred modes of compaction in a more heterogeneous system. To interpret the former result an Eshelby inclusion model was proposed to estimate analytically the local stress perturbations due to pore collapse in a homogeneous aggregate.

The acoustic emission of Westerly granite subjected to temperature changes up to 120° at various heating rates from 0.4 to 12.5°C/min was studied. A threshold temperature of 60 to 70°C appeared to exist for this range of heating rate, above which A.E. began to occur profusely with increasing temperature. Above the threshold temperature, the rate of A.E. depended strongly on the rate of heating. However, a thermal ‘Kaiser’ effect appeared to exist such that in cyclic heating and at temperatures below the maximum temperature reached in the previous cycle, very few A.E. occurred irrespect of the heating rate in the subsequent cycles. We suggest that there is an equilibrium state of the thermally induced cracks, which is a function of temperature but is independent of the heating rate; in the slower experiment, the equilibrium state of crack extension is achieved by slower growth, which is associated with smaller amounts of acoustic emission.

BackgroundTargeted next-generation sequencing (NGS) has been widely used as a cost-effective way to identify the genetic basis of human disorders. Copy number variations (CNVs) contribute significantly to human genomic variability, some of which can lead to disease. However, effective detection of CNVs from targeted capture sequencing data remains challenging.ResultsHere we present SeqCNV, a novel CNV calling method designed to use capture NGS data. SeqCNV extracts the read depth information and utilizes the maximum penalized likelihood estimation (MPLE) model to identify the copy number ratio and CNV boundary. We applied SeqCNV to both bacterial artificial clone (BAC) and human patient NGS data to identify CNVs. These CNVs were validated by array comparative genomic hybridization (aCGH).ConclusionsSeqCNV is able to robustly identify CNVs of different size using capture NGS data. Compared with other CNV-calling methods, SeqCNV shows a significant improvement in both sensitivity and specificity.Electronic supplementary materialThe online version of this article (doi:10.1186/s12859-017-1566-3) contains supplementary material, which is available to authorized users.

No abstract

It is known from the research of active tectonics that the northern margin of Tianshan mountains is characterized by typical intra‐continental active tectonics, and has multiple thrust faults and anticlines parallel to the mountains. In order to investigate the fine crustal structure and the geometry of major faults, as well as the deep‐shallow tectonic relations in the Ürümqi depression, a deep seismic reflection profile of 78 km long in near‐SN direction was completed in 2004. This profile is located in the transition zone between Tianshan Mountains and Junggar Basin to the west of Ürüumqi. The results show that the crust beneath the investigated area is divided into upper and lower crusts by a strong reflective zone at about 9~10.5 s TWT. The thicknesses of the upper and lower crusts are about 26~28 and 23~25 km, respectively. There are rich reflective layers and clear structural patterns above 5 s TWT as well as obviously different structural features along the profile. In the southern region of Xishan, the stacked deep seismic reflection section shows a series of EW‐striking thrust anticlines arranged in SN direction as well as a group of faults thrusting from south to north. All of these are influenced by a deep detachment zone. In the Xishan and Wangjiagou area, there is a set of steeply north‐dipping reflective layers and a group of faults slipping along the layers. The northern part of the profile shows the image of a typical sediment basin and its deepest depth is about 10~12 km. Between 6 and 9 s TWT, the stacked deep seismic reflection section shows disordered reflections with comparatively short continuation time and weak energy. These indicate that this part of the crust is evidently possessed of “reflection transparence”. The Moho transition zone occurs at 14~17 s TWT, and the zone thickness is about 9~10 km. In the studied area, the Moho discontinuity gradually deepens from north to south. Its depth is about 50~52 km at the northern segment of the profile and is about 54~55 km near north Tianshan. In the neighborhood of Xishan at the middle profile, the reflections from the boundary between upper and lower crusts as well as the Moho transition zone become misty while the shallow stratums show signs of uplift and fold, which may be related with the compression between Junggar basin and Tianshan mountains.

After unified reprocessing of the 18 DSS profiles data that are got in various periods in the Capital Circle area, a digital crust of velocity gridding is obtained with sample density 0.25°×0.25°×(2 ~ 5)km. Through 3‐D data visualization, the slice sections along different strikes and at different depths are calculated and showed. In this paper, the tectonic characteristics of the three main geological units, which control the crust in the Capital Circle area and include the Yanshan uplift region in the north, the Taihang uplift region in the southwest and the depression basins in the southeast, and the tectonic features of the contact zone—the Zhangjiakou‐Bohai seismic zone are studied from various aspects. Furthermore, the relation between the crustal structure of the Capital Circle area and the generation of catastrophic earthquakes is also researched.

Based on schematically formulation of the vibrations induced by moving trains, this paper analyses the waveforms along the Datong-Qinhuangdao railroad in Northern China recorded in the suburban Huairou district of Beijing on March 8, 2003. It is illustrated that vibrations induced by train, except traditional recognized noises and interference effects, could be used as a seismic source to detect crustal structures with its advantage of abundant frequency spectrum, repeatability and no additional harm to the environment. It will bring lights to the traditional exploration seismology with the further studies of signal processing and interpretation methods, and related models and new observing systems.

No abstract