Global trends of tropopause folds in recent decades

对流层顶折卷是平流层-对流层物质交换的主要机制.本研究采用三维标记方法,利用1979-2020年间的ERA5再分析数据,分析了对流层顶折卷的时空变化特征及机理.研究结果表明,全球对流层顶折卷的多年变化趋势存在明显的季节性和区域性差异.总体上,对流层顶折卷呈增加趋势,其中北半球的春季,夏季和冬季,对流层顶折卷主要沿副热带急流区呈现明显增加的趋势.进一步分析表明,对流层顶折卷发生频率的增加与大气斜压性增大导致的锋生增强有关,而经向位温梯度的增大使得次级环流增强,也可能促进了对流层顶折卷活动的增多.

Optical coherence tomography enhanced depth imaging of chorioretinal folds in patients with orbital tumors

AIM:To characterize spectral-domain optical coherence tomography(SD-OCT)features of chorioretinal folds in orbital mass imaged using enhanced depth imaging(EDI).METHODS:Prospective observational case-control study was conducted in 20 eyes of 20 patients,the uninvolved eye served as a control.All the patients underwent clinical fundus photography,computed tomography,EDI SDOCT imaging before and after surgery.Two patients with cavernous hemangiomas underwent intratumoral injection of bleomycin A5;the remaining patients underwent tumor excision.Patients were followed 1 to 14mo following surgery(average follow up,5.8mo).RESULTS:Visual acuity prior to surgery ranged from 20/20 to 20/200.Following surgery,5 patients’visual acuity remained unchanged while the remaining 15 patients had a mean letter improvement of 10(range 4 to 26 letters).Photoreceptor inner/outer segment defects were found in 10 of 15 patients prior to surgery.Following surgical excision,photoreceptor inner/outer segment defects fully resolved in 8 of these 10 patients.CONCLUSION:Persistence of photoreceptor inner/outer segment defects caused by compression of the globe by an orbital mass can be associated with reduced visual prognosis.Our findings suggest that photoreceptor inner/outer segment defects on EDI SD-OCT could be an indicator for immediate surgical excision of an orbital mass causing choroidal compression.

Conformational dynamics as an intrinsic determinant of prion protein misfolding and neurotoxicity

The prion protein(PrP) is the key molecular and pathological mediator of prion diseases,a heterogeneous group of brain disorders with fatal outcomes.Prion diseases are rare but deserve special attention because of their unique familial,sporadic,and transmissible etiologies,all caused by a single agent:misfolded conformations of PrP.

MAUN:Memory-Augmented Deep Unfolding Network for Hyperspectral Image Reconstruction

Spectral compressive imaging has emerged as a powerful technique to collect the 3D spectral information as 2D measurements.The algorithm for restoring the original 3D hyperspectral images(HSIs)from compressive measurements is pivotal in the imaging process.Early approaches painstakingly designed networks to directly map compressive measurements to HSIs,resulting in the lack of interpretability without exploiting the imaging priors.While some recent works have introduced the deep unfolding framework for explainable reconstruction,the performance of these methods is still limited by the weak information transmission between iterative stages.In this paper,we propose a Memory-Augmented deep Unfolding Network,termed MAUN,for explainable and accurate HSI reconstruction.Specifically,MAUN implements a novel CNN scheme to facilitate a better extrapolation step of the fast iterative shrinkage-thresholding algorithm,introducing an extra momentum incorporation step for each iteration to alleviate the information loss.Moreover,to exploit the high correlation of intermediate images from neighboring iterations,we customize a cross-stage transformer(CSFormer)as the deep denoiser to simultaneously capture self-similarity from both in-stage and cross-stage features,which is the first attempt to model the long-distance dependencies between iteration stages.Extensive experiments demonstrate that the proposed MAUN is superior to other state-of-the-art methods both visually and metrically.Our code is publicly available at https://github.com/HuQ1an/MAUN.

Mutation in a non-force-bearing region of protein L influences force-dependent unfolding behavior

Single-molecule magnetic tweezers(MTs) have revealed multiple transition barriers along the unfolding pathway of several two-state proteins, such as GB1 and Csp. In this study, we utilized MTs to measure the force-dependent folding and unfolding rates of both protein L(PLWT) and its Y47W mutant(PLY47W) where the mutation point is not at the force-bearing β-strands. The measurements were conducted within a force range of 3–120 pN. Notably, the unfolding rates of both PLWT and PWY47W exhibit distinct force sensitivities below 50 pN and above 60 pN, implying a two-barrier free energy landscape. Both PLWT and PLY47W share the same force-dependent folding rate and the same transition barriers,but the unfolding rate of PLY47W is faster than that of PLWT. Our finding demonstrates that the residue outside of the force-bearing region will also affect the force-induced unfolding dynamics.

Petrogenesis and Tectonic Implications of the Early Triassic Nianzi Adakitic Granite Unit in the Yanshan Fold and Thrust Belt:New Constraints from U-Pb Geochronology and Sr-Nd-Hf Isotopes

The Nianzi granite unit,which includes the Nianzi,Xiaolianghou and Xiawopu granitic intrusions,is a significant component of the northern part of the North China Craton(NCC)and is situated in the Yanshan fold and thrust belt(YFTB).However,there is still debate regarding the tectonic evolutionary history of the YFTB during the late Permian to Triassic period,specifically regarding the timing of subduction and collision between the NCC and the Paleo-Asian Ocean.The Nianzi granite unit exhibits unique petrological,geochronological and geochemical signatures that shed light on the tectonic evolutionary history of the YFTB.This study presents detailed petrology,whole-rock geochemistry,together with Sr-Nd isotopic,zircon U-Pb dating and Lu-Hf isotopic data of the granites within the Nianzi granite unit.Our findings demonstrate that the granites primarily consist of subhedral K-feldspar,plagioclase,quartz,minor biotite and hornblende,with accessory titanite,apatite,magnetite and zircon.Zircon U-Pb dating indicates that the Xiaolianghou granite was emplaced at 247.5±0.62 Ma.Additionally,the adakitic characteristics of the Nianzi,Xiawopu and Xiaolianghou granitic intrusions,such as high Sr and Ba contents and high ratios of Sr/Y and(La/Yb)N,combined with negative Sr-Nd and Lu-Hf isotopes(87Sr/86Sr)i=0.705681–0.7057433,εNd(t)=−21.98 to−20.97,zirconεHf(t)=−20.26 to−9.92,as well as the I-type granite features of high SiO_(2),Na_(2)O and K_(2)O/Na_(2)O ratios,enriched Rb,K,Sr and Ba,along with depleted Th,U,Nb,Ta,P and Ti,suggest that the Nianzi granitic unit was mainly derived from the partial melting of a thickened lower crust containing hydrous,calc-alkaline to high-K calc-alkaline,mafic to intermediate metamorphic rocks.In light of these parameters,we further integrate our data with previous studies and conclude that the Nianzi granitic unit was generated in a post-collisional extensional environment during the Early Triassic.

Flow field, sedimentation, and erosion characteristics around folded linear HDPE sheet sand fence: Numerical simulation study

Wind and sand hazards are serious in the Milan Gobi area of the Xinjiang section of the Korla Railway. In order to ensure the safe operation of railroads, there is a need for wind and sand protection in heavily sandy areas. The wind and sand flow in the region is notably bi-directional. To shield railroads from sand, a unique sand fence made of folded linear high-density polyethylene(HDPE) is used, aligning with the principle that the dominant wind direction is perpendicular to the fence. This study employed field observations and numerical simulations to investigate the effectiveness of these HDPE sand fences in altering flow field distribution and offering protection. It also explored how these fences affect the deposition and erosion of sand particles. Findings revealed a significant reduction in wind speed near the fence corner;the minimum horizontal wind speed on the leeward side of the first sand fence(LSF) decreased dramatically from 3 m/s to 0.64 m/s. The vortex area on the LSF markedly impacted horizontal wind speeds. Within the LSF, sand deposition was a primary occurrence. As wind speeds increased, the deposition zone shrank, whereas the positive erosion zone expanded. Close to the folded corners of the HDPE sand fence, there was a notable shift from the positive erosion zone to a deposition zone. Field tests and numerical simulations confirmed the high windproof efficiency(WE) and sand resistance efficiency(SE) in the HDPE sand fence. Folded linear HDPE sheet sand fence can effectively slow down the incoming flow and reduce the sand content, thus achieving good wind and sand protection. This study provides essential theoretical guidance for the design and improvement of wind and sand protection systems in railroad engineering.

Protective benefit of folded linear HDPE board sand fences along the Golmud-Korla Railway,China:Field observation and wind tunnel study

The Milan Gobi area of the Golmud-Korla Railway in northwest China is located in the lower dispersal area of the mountain pass and has strong winds with evident double wind direction characteristics.This study introduced a novel sand fence deployment technique,termed‘folded linear deployment',designed to position the sand fence orthogonally to the two predominant wind directions for optimal protection.This study used wind tunnel and field tests to evaluate the wind and sand flow characteristics,as well as the windproof and sandresistant performance of folded linear HDPE(Highdensity polyethylene)board sand fences.The results suggest that the airflow around the fence creates clear zoning characteristics.The deceleration area on the BSF(backwind side of the sand fence)is much larger than that on the DSF(downwind side of the sand fence).Thus,sand particles are primarily deposited on the BSF.At different wind speeds,the airflow at 2 and 5 h on the DSF is not disturbed.The WSP(wind speed profile)presents a logarithmic distribution.The airflow is disturbed at 1-20 h on the BSF,and the WSP gradually deviates from the logarithmic law.However,as the airflow moves away from the fence,the WSP gradually approaches a logarithmic distribution.Meanwhile,the WPE(windproof efficiency)and SRE(sand-resistant efficiency)of the sand fence exceed 80%.In addition,the results of wind tunnel tests are compared with those of field tests.The overall dispersion is good,and the best dispersion is found at z/H=2.00,indicating good agreement between the two test results.This study provides a scientific basis for the design of sand hazard control measures,similar to the railway project in the Gobi Gale area.

Wideband spectrum sensing using step-sampling based on the multipath nyquist folding receiver

Wideband spectrum sensing with a high-speed analog-digital converter(ADC) presents a challenge for practical systems.The Nyquist folding receiver(NYFR) is a promising scheme for achieving cost-effective real-time spectrum sensing,which is subject to the complexity of processing the modulated outputs.In this case,a multipath NYFR architecture with a step-sampling rate for the different paths is proposed.The different numbers of digital channels for each path are designed based on the Chinese remainder theorem(CRT).Then,the detectable frequency range is divided into multiple frequency grids,and the Nyquist zone(NZ) of the input can be obtained by sensing these grids.Thus,high-precision parameter estimation is performed by utilizing the NYFR characteristics.Compared with the existing methods,the scheme proposed in this paper overcomes the challenge of NZ estimation,information damage,many computations,low accuracy,and high false alarm probability.Comparative simulation experiments verify the effectiveness of the proposed architecture in this paper.

Tectonic evolution of the Dabashan orocline, central China: Insights from the superposed folds in the eastern Dabashan foreland

The Dabashan orocline is situated in the northwestern margin of the central Yangtze block,central China.Previous studies have defined the orthogonal superposed folds growing in its central-western segment thereby confirming its two-stage tectonic evolution history.Geological mapping has revealed that more types of superposed folds have developed in the eastern segment of the orocline,which probably provides more clues for probing the structure and tectonic history of the Dabashan orocline.In this paper,based on geological mapping,structural measurements and analyses of deformation,we have identified three groups of folds with different trends （e.g.NW-,NE-and nearly E-trending folds） and three types of structural patterns of superposed folds in the eastern Dabashan foreland （e.g.syn-axial,oblique,and conjunctional superposed folds）.In combination with geochronological data,we propose that the synaxial superposed folds are due to two stages of ～N-S shortening in the west and north of the Shennongjia massif,and that oblique superposed folds have been resulted from the superposition of the NW-and NE-trending folds onto the early ～ E-W folds in the east of the Shennongjia massif in the late Jurassic to early Cretaceous.The conjunctional folds are composed of the NW-and NE-trending folds,corresponding to the regional-scale dual-orocline in the eastern Sichuan as a result of the southwestward expansion of the Dabashan foreland during late Jurassic to early Cretaceous,coeval with the northwestward propagation of the Xuefengshan foreland.Integration of the structure and geochronology of the belt shows that the Dabashan orocline is a combined deformation belt primarily experiencing a twostage tectonic evolution history in Mesozoic,initiation of the Dabashan orocline as a foreland basin along the front of the Qinling orogen in late Triassic to early Jurassic due to collisional orogeny,and the final formation of the Dabashan orocline owing to the southwestward propagation of the Qinling orogen during late Jurassic to early Cretaceous intra-continental orogeny.Our studies provide some evidences for understanding the structure and deformation of the Dabashan orocline.

Conceptual models for fracturing in fault related folds

Fault related folds and fractures, which always improve reservoirs and trap capacity, especially in the oil and gas fields in western China, are of extreme importance for oil and gas exploration. Based on four assumptions and fault related fold theory, we propose four conceptual models for fracturing in fault related folds, i.e., a simple-step parallel fault bend anticline, a simple-step parallel fault propagation anticline, a multiple-bend fault-bend fold and a break-forward imbricate. Fracture conditions depend on structural evolution and specific site conditions. A case study of the Kulongshan Anticline in the Jiuquan Basin shows that our conceptual models match reality data very well.

Fractal Simulation and Classification of Folds

Abstract: The method of fractal simulation and classification of folds is firstly studied here to describe various types of complex fold patterns in quantitative analysis. Based on the characteristics of natural folds with a fractal pattern, the fold patterns are simulated to describe various types of folds quantitatively by means of fractal interpolation. The major factors affecting the fold pattern are elucidated in fractal simulation of folds, i.e. positions of interpolation points (x, y) and the disturbance coefficient d of folds (-1<d<1). The bigger the value d for a fold simulation is, the more complex or disturbed the folds are and the better developed the relative secondary folds are. If d>0, folds are upconvex. IF d<0, they are down-convex. |d|=0, |d|=0.25 and |d|=0.5 represent three conspicuous turning states. If |d|=0, the points will be joined by a straight line. If |d|=0.25, the points will be joined smoothly. If |d|<0.25, there will be complex secondary folds between the points. If |d| >0.5, there will be more complex secondary folds between the points. The complex degrees of the fold pattern, therefore, can be classified by the disturbance coefficient d and by the discongruent degree Δ d. In nature, most folds are self-affine fractal folds.

Rheological Properties of Fractal Deformation in Multilayer Folds

The fractal dimensions of folds are related to layer thickness and viscosity of the multilayer. This paper discusses how the thickness, viscosity, and anisotropic degree affect the rheological deformation of fractal folds in multilayers. The number of layers, their thicknesses, viscosities, and anisotropic degree of multilayers cooperate to affect the rheological deformation of folds, which is not controlled by a single rheological factor. A greater anisotropic degree of multilayers is favorable to develop the more complex and disharmonious fractal folds.

Synthesis and Solution Properties of Comb-like Acrylamide Copolymers

A comb-like acrylamide copolymer （HCJ-1） was synthesized by using aqueous free radical polymerization of acrylamide （AM） as main monomer and ether carboxylate as functional monomer. The copolymers were characterized with FT-IR and SEM. The SEM results show that the molecular structure of copolymer is extended in salt water. It is proved that the copolymer shows good salt resistance.The solution properties of HCJ-1 were studied and compared with those of partially hydrolyzed polyacrylamide （HPAM）. The experimental results show that the obtained HCJ-1, compared with HPAM, exhibits a dramatic enhancement in the salt-resistant properties. The apparent viscosity retention rate of 1.5 g/L HCJ-1 aqueous solution and salt solution after 180 days at 60 ℃ are 70.6% and 64.5%, respectively, exhibiting good thermal stability. In addition, HCJ-1 solution also displays the excellent shearing resistance. In a word, the experimental results show the HCJ-1 is a promising profiling agent for high salinity reservoir.

ELASTIC BEHAVIOR OF COMB-LIKE POLYMER CHAINS

Three-dimensional Monte Carlo simulations of comb-like polymer chains with various backbone lengths Nb, arm lengths Na and arm densities m are carried out to study the elastic behavior of comb-like polymer chains. The radius of gyration, the shape factors and bond length in different cases during elastic process are calculated, and it is found that the comb-like polymer molecules with longer backbone or shorter arm are more close to linear chains. But the arm density rn affects the chain conformation non-monotonously. Some thermodynamic properties are also studied. Average Helmholtz free energy and elastic force fall increase with elongation ratio 2 for all chains.

Enlarged folds on endoscopic gastritis as a predictor for submucosal invasion of gastric cancers

BACKGROUND Accurate diagnosis of the depth of gastric cancer invasion is crucial in clinical practice.The diagnosis of gastric cancer depth is often made using endoscopic characteristics of the tumor and its margins;however,evaluating invasion depth based on endoscopic background gastritis remains unclear.AIM To investigate predicting submucosal invasion using the endoscopy-based Kyoto classification of gastritis.METHODS Patients with gastric cancer detected on esophagogastroduodenoscopy at Toyoshima Endoscopy Clinic were enrolled.We analyzed the effects of patient and tumor characteristics,including age,sex,body mass index,surveillance endoscopy within 2 years,current Helicobacter pylori infection,the Kyoto classification,and Lauren’s tumor type,on submucosal tumor invasion and curative endoscopic resection.The Kyoto classification included atrophy,intestinal metaplasia,enlarged folds,nodularity,and diffuse redness.Atrophy was characterized by non-reddish and low mucosa.Intestinal metaplasia was detected as patchy whitish or grayish-white flat elevations,forming an irregular uneven surface.An enlarged fold referred to a fold width≥5 mm in the greater curvature of the corpus.Nodularity was characterized by goosebump-like multiple nodules in the antrum.Diffuse redness was characterized by uniform reddish nonatrophic mucosa in the greater curvature of the corpus.RESULTS A total of 266 gastric cancer patients(mean age,66.7 years;male sex,58.6%;mean body mass index,22.8 kg/m2)were enrolled.Ninety-three patients underwent esophagogastroduodenoscopy for surveillance within 2 years,and 140 had current Helicobacter pylori infection.The mean Kyoto score was 4.54.Fifty-eight cancers were diffuse-type,and 87 cancers had invaded the submucosa.Multivariate analysis revealed that low body mass index(odds ratio 0.88,P=0.02),no surveillance esophagogastroduodenoscopy within 2 years(odds ratio 0.15,P<0.001),endoscopic enlarged folds of gastritis(odds ratio 3.39,P=0.001),and Lauren’s diffuse-type(odds ratio 5.09,P<0.001)were independently associated with submucosal invasion.Similar results were obtained with curative endoscopic resection.Among cancer patients with enlarged folds,severely enlarged folds(width≥10 mm)were more related to submucosal invasion than mildly enlarged folds(width 5-9 mm,P<0.001).CONCLUSION Enlarged folds of gastritis were associated with submucosal invasion.Endoscopic observation of background gastritis as well as the lesion itself may help diagnose the depth of cancer invasion.

Study on folds of monolayer sandwiched-in different thickness terranes

The paper discussed the limitation of ’Dominant wavelengt h theory’. The theoretical model and nonhomogeneous differential equation of fold and deformation of a monolayer sandwiched-in limited and different thickn ess terranes are proposed by using mechanics of elasticity. In addition, the ′D ominant wavelength theory’ is proved by the experimental folding in elastic ma terials. The folds of a monolayer sandwiched-in limited and different thickness terranes are studied inside and are explored in the field.

QUATERNARY GROWTH FOLDS IN THE JIUXI BASIN AT THE NORTHEASTERN MARGIN OF THE QINGHAI—XIZANG PLATEAU

As a consequence of the collision of India with Asia, the Qilian Shan, rising 4000～5000m above the Gobi, marks the northeastern boundary of the Tibet—Qinghai Plateau. The Qilian Shan developed as a WNW—ESE fold\|and\|thrust belt with most of the movement directed towards the NEN—NE. Its foreland margin, the Jiuxi Basin, accommodates thick sequences of Late Cenozoic alluvial sediments derived from the Qilian Shan. Thin\|skinned fold\|and\|thrust deformation in the Jiuxi basin flanking the Qilian Shan, feature Mesozoic and Cenozoic sedimentary rocks that have been detached from the underlying basal decollement and folded into a series of NW—WNW trending anticlines and synclines. Towards the south deformation in the Jiuxi basin is accommodated by a west\|north\|west fold train (Qingcaowan, Laojunmiao, and Shiyougou folds) developed during the Quaternary. These form a distinct topographic feature separating the Qilian Shan from the central Jiuxi Basin. The doubly plunging Laojunmiao anticline is 10km long and 5km wide. It is asymmetric in shape, having a steep to overturned northern limb, and a backlimb dips to the south at 20～30°. The Laojunmiao anticline is composed of two distinct stratigraphic sequences which are defined by a syntectonic unconformity.

Recognition of Protein Native Folds Using a Continuous Potential Function

e report a simple continuous potential function that can recognize proteinchains' native folds from tens of thousands of alternative ones. Empirical parame-ters for this potential function were obtained by a neural network learning oversamples generated from PDB structural data.Hydrophobic interactions were foundto be mainly responsible for stabilization of the protein' s native fold. The inter-chain interaction was found indispensable in stabilizing some protein chains' nativeconformation.

Geometries and mechanism of folds in sediments on the southern Huanghai Sea shelf

Most descriptions and studies about folds have been associated with consolidated strata; fold deformation in loosely-consolidated sediments, however, has been rarely discussed. Since the Pleistocene, tectonic activities have been intensive over the South Huanghai Sea （SHS） shelf, resulting in fold deformation features that are preserved in thick sediment layers. Four types of folds with different geometries have been identified on the basis of an analysis of single - channel seismic profiles from the SHS shelf region： （1） fault-propagation fold; （2） fault-drag fold; （3） transversal bending fold; and （4） multi-action-folding fold. Studies on the geometry and mechanism of the folds indicate that base faults and fault blocks control the folding patterns in loosely-consoli- dated sediments on the SHS shelf and a large quantity of pore water in sediments plays an important role in cansing the deformation of sediment layers. The continuity of deformations of fault-propagation fold and fault-drag fold indicates that there is a genetic relationship between these fold types. The potential of earthquakes induced by fault-propagation folding in the deformation zone should be taken into account in the assessment of the marine engineering geology conditions of the SHS shelf.