Coupled GIMP and CPDI material point method in modelling blast-induced three-dimensional rock fracture

Three-dimensional rock fracture induced by blasting is a highly complex problem and has received considerable attention in geotechnical engineering.The material point method is firstly applied to treat this challenging task.Some inherent weaknesses can be overcome by coupling the generalized interpolation material point(GIMP)and the convected particle domain interpolation technique(CPDI).For the media in the borehole,unchanged GIMP-type particles are used to guarantee a homogenous blast pressure.CPDITetrahedron type particles are employed to avoid the fake numerical fracture near the borehole for the rock material.A blasting experiment using three-dimensional single-borehole rock was simulated to examine the applicability of the coupled model under realistic loading and boundary conditions.A good agreement was achieved between the simulation and experimental results.Moreover,the mechanism of three-dimensional rock fracture was analyzed.It was concluded that rock particle size and material parameters play an important role in rock damage.The reflected tensile waves cause severe damage in the lower part of the model.Rayleigh waves occur on the top face of the rock model to induce a hoop failure band.

Enhancement of spatial resolution of ghost imaging via localizing and thresholding

In ghost imaging, an illumination light is split into test and reference beams which pass through two different optical systems respectively and an image is constructed with the second-order correlation between the two light beams. Since both light beams are diffracted when passing through the optical systems, the spatial resolution of ghost imaging is in general lower than that of a corresponding conventional imaging system. When Gaussian-shaped light spots are used to illuminate an object, randomly scanning across the object plane, in the ghost imaging scheme, we show th√at by localizing central positions of the spots of the reference light beam, the resolution can be increased by a factor of 2^(1/2) same as that of the corresponding conventional imaging system. We also find that the resolution can be further enhanced by setting an appropriate threshold to the bucket measurement of ghost imaging.

Intensity-modulated radiotherapy for breast cancer:a systematic review

Objective:The aim of this study was to assess the long-term effect of breast conservation with breast intensitymodulated radiotherapy (IMRT) for early-stage breast cancers.Methods:Pub Med,EMBASE,Cochrane Library,Chinese Biomedical Literature Database were searched to identify relevant original published trails,and the references of eligible studies were manually screened.Randomized controlled trails reported in any language,comparing breast IMRT with conventional radiotherapy (RT) in patients with early-stage breast cancer were eligible for inclusion.Two investigators independently assessed the quality of included trials and extracted data.The RevMan 5.0 software was used for statistical analysis.Results:Four trials involving 1440 patients were included.The results showed that in the IMRT group,the occurrence of acute moist dermatitis,the edema of the mammary gland and the occurrence of hyperpigmentation were lower than those of RT group,the pooled risk ratio value and 95% confidence interval were 0.28 (0.17-0.48),0.03 (0.00-0.21) and 0.06 (0.02-0.15) respectively.The use of IMRT did not correlate with pain and quality of life,but the presence of moist desquamation did significantly correlate with pain and reduced quality of life.Conclusion:The currently available evidence showed that IMRT significantly reduces the occurrence of moist acute dermatitis anywhere in the breast and alleviates the suffering of patients and improves the quality of life of patients.Future large-scale,high-quality,double-blind trials are needed.

Radiotherapy combined with surgical treatment for gastric cancer:a meta-analysis

Objective:We carried out a meta-analysis to assess the effectiveness and safety of radiotherapy combined with surgery for gastric cancer.Methods:Randomized Clinical Trials (RCTs) in which radiotherapy (preoperative,intraoperative and postoperative),was compared with surgery alone in resectable gastric cancer were identified by searching Cochrane Library (Issue 2,2009),PubMed (Jan 1966-Jun 2009),EMBASE (Jan 1974-Jun 2009),Chinese Biomedical Literature Database (Jan 1978-Jun 2009),Chinese Science and Technology Periodicals Database (Jan 1989-Jun 2009),China National Knowledge Infrastructure (Jan 1994-Jun 2009) and Wanfang database (Jan 1997-Jun 2009) in English and Chinese languang.Two researchers assessed the quality of included randomized controlled trials (RCT) extracted data independently.The RevMan 5.0 software was used for meta-analysis.Our researchers assessed the quality of included randomized controlled trials (RCT) extracted data independently.The RevMan 5.0 software was used for meta-analysis.Results:Nine randomized controlled trials of 1 548 patients were selected for meta-analysis.Five randomized controlled trials were related with comparison of preoperative radiotherapy plus surgery with single surgery.Two randomized controlled trials were the comparative studies between surgery plus postoperative and single surgery.The meta-analysis results showed that:(1) compared with surgery alone,preoperative radiotherapy combined with surgery can increase 3 years (OR=1.78;95% CI 1.14-2.78,P=0.01),5 years (OR=1.67;95% CI 1.22-2.29,P=0.001),10 years (OR=1.64;95% CI 1.03-2.60,P=0.04) survival rate and resection rate (OR=2.15;95% CI 1.31-3.54,P=0.003);reduce the of tumor recurrence rate (OR=0.59;95% CI 0.37-0.92,P=0.02) and metastasis rate (OR=0.44;95% CI 0.27-0.73,P=0.001);(2) The tumor recurrent rates (OR=0.19,95% CI 0.03-1.14,P=0.07) and tumor metastasis rate (OR=0.09;95% CI 0.00-1.77,P=0.11) had no difference between single surgery group and peri-operative radiotherapy plus surgery group;(3) Postoperative radiotherapy compared with surgery alone had no significant effects on 1 year (OR=0.83;95% CI 0.60-1.15,P=0.26) and 3 years (OR=0.75;95% CI 0.51-1.11,P=0.15) survival rate compared with single surgery,but the 5-year survival rates (OR=0.57;95% CI 0.34-0.95,P=0.03) of the patients who received surgery alone was higher than those who received combined therapy.No difference of the tumor recurrence rate (OR=0.59;95% CI 0.33-1.05,P=0.07),tumor metestasis rate (OR=0.90;95% CI 0.51-1.59,P=0.71) and anastomotic leak (OR=0.98;95% CI 0.25-3.65,P=0.98) were observed between the two groups.Conclusion:Preoperative radiotherapy combined surgery is more rational and effective than surgery alone of gastric cancer.However,in terms of the clinical effects of perioperarive or postoperative radoiotherapy combined with surgery,much multicenter,largescale,high-quality,double-blind and rigorously designed studies would be needed than currently available in the future.

Defects and asymmetries in the visual pathway of non-human primates with natural strabismus and amblyopia

Strabismus and amblyopia are common ophthalmologic developmental diseases caused by abnormal visual experiences. However, the underlying pathogenesis and visual defects are still not fully understood. Most studies have used experimental interference to establish diseaseassociated animal models, while ignoring the natural pathophysiological mechanisms. This study was designed to investigate whether natural strabismus and amblyopia are associated with abnormal neurological defects. We screened one natural strabismic monkey(Macaca fascicularis) and one natural amblyopic monkey from hundreds of monkeys, and retrospectively analyzed one human strabismus case. Neuroimaging, behavioral,neurophysiological, neurostructural, and genovariation features were systematically evaluated using magnetic resonance imaging(MRI), behavioral tasks, flash visual evoked potentials(FVEP),electroretinogram(ERG), optical coherence tomography(OCT), and whole-genome sequencing(WGS), respectively. Results showed that the strabismic patient and natural strabismic and amblyopic monkeys exhibited similar abnormal asymmetries in brain structure, i.e., ipsilateral impaired right hemisphere. Visual behavior, visual function, retinal structure, and fundus of the monkeys were impaired. Aberrant asymmetry in binocular visual function and structure between the strabismic and amblyopic monkeys was closely related, with greater impairment of the left visual pathway.Several similar known mutant genes for strabismus and amblyopia were also identified. In conclusion,natural strabismus and amblyopia are accompanied by abnormal asymmetries of the visual system,especially visual neurophysiological and neurostructural defects. Our results suggest that future therapeutic and mechanistic studies should consider defects and asymmetries throughout the entire visual system.

Preliminary study of lateral variation in crustal structure of Northeast China from teleseismic receiver functions

We conducted comprehensive receiver function analyses for a large amount of high-quality broadband teleseismic waveforms data recorded at 19 China National Digital Seismic Network （CNDSN） stations deployed in Northeast China. An advanced H-κ domain search method was adopted to accurately estimate the crustal thickness and vp/vs ratio. The crust has an average thickness of about 34.4 km. The thinnest crust occurs in the central region of Northeast China, while the thickest crust is beneath the Yanshan belt. The vp/vs ratio is relatively uniform with an average of about 1.733. The highest vp/vs ratio is found beneath the Changbaishan, likely associated with its volcanic activities. We found significant lateral heterogeneity beneath three stations CN2, MDJ, and MIH located along the Suolon suture from the back-zimuthal dependence of Moho depth. The velocity modeling from receiver functions indicated complicated Earth structure beneath these stations with large crust-mantle transition zone, noticeable velocity jump in upper mantle, and low velocity zone in middle crust. Dipping velocity interface in the crust with strike approximately parallel to the Suolon suture and down-dip to the south or southeast might explain the observed lateral heterogeneity.

Climate change and village adaptation impact on reliability of irrigation wells in China

This paper builds a water supply reliability econometric model to analyze climate changes and adaptation impact factors on water supply reliability of irrigation wells by using 100 villages' three-year(2010-2012) field survey data of five middle and eastern provinces of China.The results show that long-run climate change factors,adaptation measures,village-level organizations of irrigation management,as well as extreme climate factors affect the water supply reliability of irrigation wells significantly.Meanwhile,there are significant differences impacting different crops and provinces.This paper suggests that agriculture meteorological disaster monitoring and warning systems should be strengthened by increasing irrigation facilities construction and maintenance,promoting reform of agricultural irrigation water management system,and developing various forms of peasant cooperation organization in order to improve agricultural production capacity to adapt to climate change.

Focal mechanism of Luding M 6.8 earthquake, September 2022 and analysis of the loading role of the tectonic stress on the seismogenic fault

To reveal the seismogenic mechanism of the Luding earthquake, we employed the 118 China Seismic Network stations to collect the P-wave polarity data from each station, which was then used in the P-wave first motion approach to calculate the focal mechanism solution of the M6.8 Luding earthquake that occurred on September 5,2022. We have also studied the loading effect of tectonic stress on the Luding earthquake fault based on the stress field data for the research area. The results indicate that this earthquake was a strike-slip type, the nodal plane I:strike 167°, dip angle 78°, slip angle 2°;Nodal plane II: strike 77°, dip angle 88°, slip angle 168°. The two fault planes’ instability coefficients of the Luding earthquake are examined considering the region’s background stress field’s condition. The nodal plane I in the Moho circle is discovered to practically coincide with the Coulomb failure line and the tangent point of the Moho circle, indicating that this nodal plane has a high instability coefficient compared to the nodal plane II. The conclusion is that the nodal plane I has a higher likelihood of being the seismogenic fault plane, which is congruent with the seismogenic fault plane suggested by the aftershock distribution, the earthquake radiation energy distribution of a single station, and seismic intensity distribution.The Luding earthquake’s focal mechanism is highly like the theoretical focal mechanism of the fault situated at the location where the Coulomb failure line intersects the Mohr circle, demonstrating that background stress is what caused the earthquake. The substantial fault instability and similarity between the solved and theoretical focal mechanisms make it easier to comprehend the loading effect of tectonic stress on the Luding earthquake fault.

Learning to recognize misaligned hyperfine orbital angular momentum modes

Orbital angular momentum(OAM)-carrying beams have received extensive attention due to their high-dimensional characteristics in the context of free-space optical communication.However,accurate OAM mode recognition still suffers from reference misalignment of lateral displacement,beam waist size,and initial phase.Here we propose a deep-learning method to exquisitely recognize OAM modes under misalignment by using an alignment-free fractal multipoint interferometer.Our experiments achieve 98.35% recognizing accuracy when strong misalignment is added to hyperfine OAM modes whose Bures distance is 0.01.The maximum lateral displacement we added with respect to the perfectly on-axis beam is about±0.5 beam waist size.This work offers a superstable proposal for OAM mode recognition in the application of free-space optical communication and allows an increase of the communication capacity.

Probing the fractional topological charge of a vortex light beam by using dynamic angular double slits

Vortex beams with fractional topological charge(FTC) have many special characteristics and novel applications.However, one of the obstacles for their application is the difficulty of precisely determining the FTC of fractional vortex beams. We find that when a vortex beam with an FTC illuminates a dynamic angular double slit(ADS), the far-field interference patterns that include the information of the FTC of the beam at the angular bisector direction of the ADS vary periodically. Based on this property, a simple dynamic ADS device and data fitting method can be used to precisely measure the FTC of a vortex light beam with an error of less than 5%.

Investigation on Fracture Properties of Single-Flawed Tunnel Model Under Medium-to-Low-Speed Impacts

Dynamic fractures occur frequently in geophysical processes and engineering applications.It is thus essential to study crack and failure behaviors,such as crack time-to-initiation,crack growth rate and arrest period under dynamic loading.In this study,impact experiments were implemented by utilizing the single-flawed tunnel specimens under drop-hammer impacts.Four brittle materials,i.e.,green sandstone,red sandstone,black sandstone and polymethyl methacrylate,were selected to make single-flawed tunnel specimens.Strain gauges and crack extension gauges were employed to measure the crack extension parameters.The properties of crack growth rate,crack time-to-initiation and arrest period of these four brittle materials were discussed and analyzed.The corresponding numerical simulation was performed by using the commercial software AUTODYN.The numerical results of crack growth rate and crack time-to-initiation agreed with the impact test results.The commercial software ABAQUS was applied to compute the dynamic stress intensity factors.The results show that both the dynamic initiation fracture toughness and the crack growth rate increase with the elastic moduli of these four types of brittle materials under the same loading conditions,whereas the crack time-to-initiation decreases with the increase in elastic moduli of the brittle materials under the same loading conditions.