Adjacent Blocks Research Articles

Constraining Andean Propagation of Exhumation at the Limit of the Eastern Cordillera, NW Argentina, Using Low‐Temperature Thermochronology in a Structural Context

AbstractWithin the Central Andes of NW Argentina, the spatiotemporal distribution and style of deformation is strongly influenced by pre‐Cenozoic heterogeneities, mostly related to the Salta rift extension in the Cretaceous. At the enigmatic junction of the thin‐skinned Subandean belt and the thick‐skinned Santa Barbara System, the Tilcara Range and adjacent San Lucas block, located within the Eastern Cordillera, show thermochronological and field evidence of multiple exhumation events. Mesozoic (140‐115 Ma), pre‐Andean exhumation of basement highs is constrained by unconformities between basement and syn‐rift strata, as well as zircon (U‐Th‐Sm)/He cooling ages. Cenozoic Andean exhumation is quantified by apatite (U‐Th‐Sm)/He and fission track cooling ages, which were reset between the Late Cretaceous and Miocene. These data show that the westernmost Tilcara Range began exhuming in the late Oligocene‐early Miocene (26‐16 Ma), after which exhumation propagated to the border of the Eastern Cordillera in the middle Miocene (22‐10 Ma). The onset of rapid exhumation in the San Lucas block, which is located east of the Tilcara Range, occurred in the late Miocene (10‐8 Ma) in its western part, and in the late Miocene‐early Pliocene (6‐4 Ma) in its eastern part. Internal deformation of the San Lucas block, disturbing zircon (U‐Th‐Sm)/He and apatite fission track age patterns, predates propagation of rapid exhumation. The here presented low‐temperature thermochronology data set thus quantifies the multi‐phase exhumation history of the Eastern Cordillera of NW Argentina and constrains the timing of Andean propagation of exhumation within the Eastern Cordillera and the adjacent structural transition zone.

Error Probability Analysis for Time-Varying Chaos Unitary Matrix-Based Differential MIMO System

The time-varying (TV) chaos unitary matrix based differential multiple-input multiple-output (D-MIMO) system is capable of achieving beneficial performance gains without channel state information (CSI). To elaborate a little further, the chaos sequence is embedded into the data-carrying matrices by a unique time-varying matrix. By employing differential coding during two adjacent signal blocks, a non-coherent detector can be developed without CSI knowledge. However, its theoretical performance analysis becomes challenging due to its complex construction. To address this issue, the theoretical average bit error probability (ABEP) lower and upper bounds of the TV-D-MIMO system are analyzed using the moment generating function (MGF) over generalized fading channel. The experimental results are shown that the derived ABEP upper and lower bounds are tight with the simulation results, which is helpful for future performance evaluation.

Circulate Matrix and Compression Sensing Based Multi-Level Image Encryption

Digital data security is a broad research area in the field of science and technology. A lot of research was focused on information security-based mechanism for secure communication. This paper presents a novel image encryption as well as compression based on measurement matrix, pixel exchange and logistic cat map, which includes the permutation, compression, and diffusion processes. Initially the image is divided into four equal sizes of blocks and then each block is transformed into horizontal and vertical low and high frequency band. Then a random matrix multiplication function is applied to achieve an encrypted and scrambling frequency component and apply inverse DWT procedure to get first level of scrambled blocks, and further we apply the second level of security mechanism. Here each adjacent block pixel is exchanged by using the random matrices. For providing the high level of compression we design measurement matrices in compressive sensing by utilizing the circulate matrices and controlling the original column vectors of the circulate matrices with Arnold cat map. With the help of measurement matrix again the blocks are encrypted. Experimental results and performance analyses validate the good compression performance and high security of the given algorithm.

Learned Block-Based Hybrid Image Compression

Recent works on learned image compression perform encoding and decoding processes in a full-resolution manner, resulting in two problems when deployed for practical applications. First, parallel acceleration of the autoregressive entropy model cannot be achieved due to serial decoding. Second, full-resolution inference often causes the out-of-memory (OOM) problem with limited GPU resources, especially for high-resolution images. Block partition is a good choice to handle the above issues, but it brings about new challenges in reducing the redundancy between blocks and eliminating block effects. To tackle the above challenges, this paper provides a learned block-based hybrid image compression (LBHIC) framework. Specifically, we introduce explicit intra prediction into a learned image compression framework to utilize the relation among adjacent blocks. Superior to context modeling by linear weighting of neighbor pixels in traditional codecs, we propose a contextual prediction module (CPM) to better capture long-range correlations by utilizing the strip pooling to extract the most relevant information in neighboring latent space, thus achieving effective information prediction. Moreover, to alleviate blocking artifacts, we further propose a boundary-aware postprocessing module (BPM) with the edge importance taken into account. Extensive experiments demonstrate that the proposed LBHIC codec outperforms the VVC, with a bit-rate conservation of 4.1%, and reduces the decoding time by approximately 86.7% compared with that of state-of-the-art learned image compression methods.

Linear frequency modulated reverberation suppression using time series models

When active radar and <span>sonar systems are used for target detection and tracking, boosting target detection, and tracking efficiency is the most important challenge in real-time reverberation. To eliminate reverberation when transmitting linear frequency modulated (LFM) signals, this study employs time series techniques such as autoregressive (AR), moving average (MA), and autoregressive moving average (ARMA). The primary purpose of this research is to whiten LFM reverberation by transforming it to a fractional domain using the fractional Fourier transform (FrFT). The LFM reverberation is a highly coloured noise whose frequency fluctuates according to the stationary hitting frequency. As a reference signal, the proposed methods make use of the adjacent signal block. The effectiveness of FrFT-based AR, MA, and ARMA pre-whitening for LFM reverberation reduction was assessed, and the results were presente</span>d.

Garden Lupin (Lupinus polyphyllus) Is a New Natural Host of Lily Symptomless Virus in Korea.

Lupinus polyphyllus (Fabaceae), commonly known as garden lupin, is cultivated for commercial, private, and gardening purposes in many countries in Europe, North America, and Asia (Ramula and Kalske 2020). No previous studies have reported viruses infecting L. polyphyllus in the Republic of Korea. In May 2021, virus-like symptoms such as stunting, chlorotic striping, and mosaic were observed on the leaves of L. polyphyllus at the Suncheonman National Garden in Suncheon, South Korea; the disease incidence was estimated to be between 10 and 20%. These symptoms were similar to those observed in lily plants infected by lily symptomless virus (LSV) (Singh et al. 2005, Flores et al. 2019). Several different species of Lilium, including lilies, were grown in the same garden with L. polyphyllus on the adjacent block. Only carlavirus-like filamentous particles (approximately 610-700 nm in length and 12-15 nm in diameter) were observed using transmission electron microscopy in negatively stained extracts from five symptomatic samples. To further investigate the causative virus, a total of 20 symptomatic leaves were collected from 20 different L. polyphyllus plants and tested by DAS-ELISA using polyclonal antibodies against viruses infecting plants from the Lilium genus, including arabis mosaic virus, cucumber mosaic virus, LSV, lily mottle virus, and plantago asiatica mosaic virus (Agdia, Elkhart, IN, USA). Commercial positive and negative controls and extract from healthy L. polyphyllus tissue were included in each ELISA. The serological analyses showed that all symptomatic samples were positive only for LSV, but not for other viruses. To further confirm LSV infection, total RNA was extracted from 10 ELISA-positive plants and two healthy L. polyphyllus plants (negative control) using Clear-S Total RNA extraction kit (InVirusTech Co., Gwangju, Korea). RT-PCRs were performed using LSV coat protein (CP) specific primers, LSV1 (5'-CACATATGCAATCAAGACCAGCAC-3') and LSV2 (5'-GAGGATCCTCATCCATTATTTGCGTATC-3'), designed to amplify an 876-nt fragment of the CP gene (Lim et al. 2009). A DNA fragment of the expected size was amplified from only the ten symptomatic leaves. Three amplified RT-PCR products were cloned into the pGEM-T Easy Vector (Promega, Madison, WI) and sequenced. The sequences obtained from each amplicon showed 100% sequence identity; a single representative sequence was deposited to GenBank (LC649240). Pairwise nucleotide sequence analysis revealed that this LSV isolate LP2 had 99% nucleotide and 100% amino acid identity with Lilium longiflorum LSV isolate from South Korea (JX962776). To fulfill Koch's postulates, sap from an LSV-positive L. polyphyllus plant was inoculated to 10 young healthy L. polyphyllus plants. At 14 days post-inoculation, all the inoculated plants showed typical symptoms of LSV infection, such as mild vein-clearing and mosaic (Asjes 2000). The LSV infection in the inoculated plants was confirmed by RT-PCR using the aforementioned primers and sequencing of the 876-nt amplicons. To the best of our knowledge, this is the first report of LSV naturally infecting L. polyphyllus in the Republic of Korea. LSV could negatively impact the quality of L. polyphyllus and trade. Thus, it is important to investigate the extent of its distribution in South Korea and how it can be effectively managed.

Pronounced Changes in Thermal Signals Associated with the Madoi (China) M 7.3 Earthquake from Passive Microwave and Infrared Satellite Data

Thermal variations in surface and atmosphere observed from multiple satellites prior to strong earthquakes have been widely reported ever since seismic thermal anomalies were discovered three decades ago. These thermal changes are related to stress accumulation caused by the tectonic activities in the final stage of earthquake preparation. In the present paper, we focused on the thermal changes associated with the 2021 Madoi M 7.3 earthquake in China and analyzed the temporal and spatial evolution of the Index of Microwave Radiation Anomaly (IMRA) and the Index of Longwave Radiation Anomaly (ILRA) based on 8-year microwave brightness temperature (MWBT) and 14-year outgoing longwave radiation (OLR) data collected by satellites. We also explored their responses in different tectonic units (seismogenic fault zone and active tectonic block). Our results indicated that the enhanced IMRA was distributed along the seismogenic fault since mid-February and reappeared for a longer time and with stronger intensity in March and April 2021. The pronounced enhancement in the ILRA was observed within one month over Bayan Har tectonic and adjacent blocks. The higher ILRA over the tectonic blocks in the southern Tibet Plateau at the beginning of 2021 could be associated with the regional stress accumulation, as proven by the occurrences of two moderate earthquakes during this period.

Detrital zircon geochronology and stratigraphy of the Proterozoic strata in the Olongbuluke terrane of Northwest China: Implications for the Great Unconformity

The Great Unconformity that separates the early Cambrian sandstones from the Proterozoic metamorphosed sedimentary rocks has been recognized in many blocks on Earth. However, whether it represents a globally synchronous event or a composite of a series of diachronous events, and its formation mechanism remain largely unknown. In this study, we carry out detrital zircon U-Pb analyses for seven samples collected from the Paleoproterozoic Quanji Group and the overlying Neoproterozoic strata in the Olongbuluke terrane (OLT) of Northwest China. The results show that apart from age populations of ∼ 1.8–2.0 Ga and ∼ 2.2–2.5 Ga for all samples, additional ∼ 1.55–1.65 Ga age population occurs in sample from the Zhoujieshan Formation, and more scattered age populations ranging from ∼ 0.75 to ∼ 1.7 Ga are present in samples from the Heitupo and Hongtiegou formations. The ∼ 1.8–2.0 Ga and ∼ 2.2–2.5 Ga zircons correlate well with the magmatic and metamorphic events in the OLT basement, indicating their local provenances, while other zircons were possibly derived from the North China craton (NCC) or other adjacent blocks. Combined with published paleontological, stratigraphic, and geochronological data, the present study supports previous inference that the OLT had a close paleogeographic affinity to the NCC during late Paleoproterozoic to Neoproterozoic. New zircon U-Pb ages indicate that the Heitupo Formation was deposited later than ∼ 750 Ma, and the underlying Hongzaoshan Formation was deposited at ∼ 1.66 Ga, implying a huge break between them. Whereas the duration of the sedimentary break between the Heitupo Formation and the overlying Hongtiegou Formation is uncertain, biostratigraphic data suggest that a break of ∼ 30 Myr may exist between the late Ediacaran Zhoujieshan Formation and the overlying early Cambrian Xiaogaolu Group. The occurrences of these multiple unconformities in OLT are comparable to those in NCC, indicating that the Great Unconformity is represented by a series of lengthy denudations during the Proterozoic-early Cambrian in both the OLT and NCC, which may result from multiple tectonic activities in these two blocks.

Reversible data hiding for JPEG images based on improved mapping and frequency ordering

Due to the good balance between file size and visual quality, JPEG images are widely used in our daily lives. Many reversible data hiding (RDH) schemes have been developed for JPEG images, most of which are based on the modification of one-dimensional (1D) histograms of DCT coefficients. Recently, two-dimensional (2D) histograms of DCT coefficients are used to improve embedding efficiency. However, the existing coefficient pairing, coefficient pair mapping and embedding order can be further optimized. In this paper, a new RDH scheme for JPEG images based on 2D histogram modification is proposed. First, according to the statistical distribution of the AC coefficients, two non-zero coefficients with the same frequency in adjacent blocks, instead of two neighboring coefficients within the same block, are paired. More coefficient pairs with higher embedding efficiency can be obtained. Then, an optimized coefficient pair mapping is presented, more specifically, the coefficient pairs that occur more frequently are given priority to use the transfer mode with higher embedding efficiency. Lastly, a new method is proposed to accurately estimate the embedding efficiency of different frequencies. The data is embedded into the coefficient pairs at the frequency position where the embedding efficiency is higher. Extensive experiments on several commonly-used images and two popular image databases show that our proposed scheme can achieve better visual quality and smaller file size increments compared to the state-of-the-art RDH schemes for JPEG images.

Oncogenic Role of Connective Tissue Growth Factor Is Associated with Canonical TGF-β Cascade in Colorectal Cancer.

TGF-β signaling pathways promote tumour development and control several downstream genes such as CTGF and MMPs. This study aimed to investigate the association between CTGF and MMP-1 mRNA expressions with clinicopathological status and survival rate in colorectal cancer patients. We investigated expression levels of CTGF and MMP-1 genes in paraffin-embedded tumours and adjacent normal tissue blocks (ADJ) by Real Time-PCR. Then, the expression of Smad2 and Smad4 proteins in the TGF-β canonical pathway was evaluated by immunohistochemistry. Finally, the correlation between CTGF, MMP-1, and the canonical TGF-β-signalling pathway with the clinicopathological features was investigated. Expression levels of MMP-1and CTGF were higher in tumours compared with adjacent normal tissues. Overexpression levels of MMP-1 and CTGF were associated with lymph node metastasis, distant metastasis, tumour histopathological grading, advanced stage, and poor survival (p < 0.05). Additionally, a significant association between the upregulation of MMP-1 and tumour location was noted. Upregulation of Smad2 and Smad4 proteins were also significantly correlated with lymph node metastasis, distant metastasis, advanced stage, and poor survival (p < 0.0001). This study showed that canonical TGF-β signalling regulates both CTGF and MMP-1 expression and CRC progression. Moreover, TGF-β signalling and its downstream genes could be used as novel biomarkers and novel approaches for targeted therapy in CRC.

Where the Crosswalk Ends: Mapping Crosswalk Coverage via Satellite Imagery in San Francisco

Marked crosswalks are the primary means of safeguarding pedestrian travel at intersections in American cities. In the face of decades-high pedestrian fatalities nationwide, the provision of adequate crosswalks is highly salient. Though, how they are spatially distributed across an entire city, and vary by neighborhood, has drawn little academic scrutiny. Given that, this study utilizes satellite imagery to map the presence of marked crosswalks throughout San Francisco, a dense, walkable city that has struggled to reach its pedestrian-safety goals. For the first time, this allows for a calculation of “crosswalk coverage” for the city as a whole. Manual review of satellite imagery documents that crosswalks are present at 58% of San Francisco’s roughly 6,400 intersections, though they are not evenly distributed across neighborhoods. Both hotspot analysis and comparing crosswalk coverage by Census tracts demonstrates that northern neighborhoods—even outside of the downtown core—maintain higher percentages of intersections with crosswalks than those in the southern half. Intersections exhibit crosswalk “corridor effects,” in that crosswalks often cluster along certain streets, including (but not limited to) commercial areas. In addition, crosswalks in four neighborhoods were analyzed to a deeper extent, including category (e.g., ladder, continental, and standard), condition, and “completeness” or the number of adjacent blocks with a connecting crosswalk. Across these roughly 1,000 intersections, coverage varied from 51% in the Bayview (a historic African American community) to 83% in Pacific Heights (a high-income, majority-white neighborhood). Though these patterns track somewhat with local pedestrian and automobile volumes, crosswalk coverage diverges from these data in many ways, indicating other factors at play in their distribution. Overall, satellite imagery can be used to identify marked crosswalks at scale, evaluate their quality, and probe geographic variation. Armed with such granular data, planners can consider the ways in which crosswalks are present throughout cities—and where notable gaps exist—in their pursuit of Vision Zero goals.

What happened to the Early Precambrian granulite complexes of the Bug region (Ukrainian shield) and the Limpopo belt (South Africa) and how to stratify them? A tectonist’s view

The author reviews two alternative approaches (stratigenic-metamorphogenic and deformation-metamorphogenic) to the geology and mapping of the Earth’s oldest crust rocks that were metamorphized in РТ-conditions of the granulite facies, on the examples of two granulite belts — the Bug area complex (Ukrainian shield) and Limpopo belt (Southern Africa).&#x0D; There was shown a fairly good correlation of the composition and metamorphism (including the dynamometamorphism) of the rock complexes of both belts and their at least three-stage origin and transformation. The granulitic metamorphism processes within both belts happened before 3,0 b.y.a., 2,6—2,8, and c. 2,0 b.y.a. The structural-metamorphic transformations of the granulitic complexes, formation of their new structural plans with the destruction of the former (archean) by the following (proterozoan) do not allow falsifiably stratifying the archean granulitic complexes within the stratigenic-metamorphogenic approach already at the facies level. For the Bug area granulitic belt it is feasible only to isolate the Dniester-Bug and Bug series. Two of the important processes of the belt development are rock deformation in the compression and slip conditions and formation within the granulitic complexes of the sub-vertically-layered medium, slip folds with sub-vertical folds’ joints and wings. In both belts these processes began in the Neoarchean. This shows that in that time the tectonic processes were already to some significant degree propelled by plate tectonics mechanisms. Both belts had in common the formation of the linear-typeshearzonesat micro- to macroscale and their superimposition onto the deformation structures of the granulitic complexes of the preceding developmental stages. On their basis there formed the internal structure of the belts’ and their interconnections with the adjacent blocks of crust. Presumably, the archean charnokitoids and TTG-granitoids form the same structural layer of the crust, given their geochemical similarity and close age, and this layer is the base for the greenstone belts. The mineral composition, РТ-metamorphism conditions and age of granulitic belt rocks based on their U-Pb, Lu-Hf, Sm-Nd isotope systems compositions andoxygen isotope composition in Zirconium grains suggest that in the eo- and paleoarchean mantle and crust there should have already been amassed large quantities of medium-acidic matter which gave rise to the TTG complexes.

An improved Criminisi method for image inpainting

The Criminisi method is a classical image inpainting method, which has flaw of unreasonable priority calculation. To overcome this flaw, we propose an improved Criminisi method. To improve the accuracy of a repaired block’s priority, we propose a novel method by considering the continuity of structure and color information between the repaired block and its adjacent blocks. When searching the matching block for a repaired block, we compute the similar between two blocks as the sum of squared differences (SSD). Since different blocks within an image may contain different levels of information, we set block to different sizes to determine the best matching block. Experimental results demonstrate the effectiveness of the proposed method.

Geological structure of the Ustoyarvi region (North-Western part of the Russian Arctic)

The paper presents data on geology and composition of rocks from the Ustoyarvi region (the North-Western Arctic zone of Russian Federation). Their compositional analysis (including mathematical evaluation of the similarity/difference measure) provided much reliable conclusion that the rocks from this area, which are presumably attributed to the Ustoyarvi structure (Ustoyarvinsky Greenstone Belt) were similar to those from the Ura-Guba area in the Kolmozero-Voronya Belt and continued it. In addition, it has been shown that from west to east lithotectonic units in the adjacent (Suormussky) Block become gradually impregnated with tectonic wedges of rocks of the Ustoyarvi Greenstone Belt. It indicates increasing collisional interaction between rock associations with a varied genesis. P-T formation parameters have been specified for komatiites from greenstone belts, i. e. the Kolmozero-Voronya, Ura-Guba, Ustoyarvi and Western Litsa area. It has been defined that komatiites of the Ustoyarvi Greenstone Belt were formed under pressure of about 5 hPa, komatiites of the Ura-Guba area - about 4.5 hPa, komatiites of the Kolmozero-Voronya - about 2 hPa. Thus, komatiites of the Ustoyarvi Greenstone Belt are more high-pressure formations.

In-depth field survey of a rockslide detachment surface to recognise the occurrence of gravity-induced cracking

This work describes field evidence of gravity-induced cracking that has been identified on the failure scar of a small rockslide (volume = 6–7 m3) that occurred in March 2004 in the Rosandra Valley near the town of Trieste (north-eastern Italy). This shallow rock slope failure involved a limestone slope that was re-profiled through blasting about 135 years ago for the construction of an old railway, which has now been reconverted into a cycle path. Field observations ascertained that the slope failure was characterised by a cascading rupture process in which adjacent blocks collapsed in rapid sequence as a result of the progressive breakage of a number of rock bridges (domino-like collapse), thus highlighting a progressive failure mechanism. The rock bridges were localised in eccentric positions on lateral and rear release planes and failed in tension as a result of combined tensile and bending loading conditions (tensile strength of intact rock = 5 ± 2 MPa). The rockslide was triggered by cyclic loading related to freeze-thaw (ice jacking) that occurred over some consecutive days of daily snowmelt and nocturnal frost. The recognition of newly formed fractures also proves the current progressive development of 3D rupture surfaces of some unstable blocks susceptible to failure. This study provides innovative content to detect gravity-induced cracking in the field, which is an important precursory sign relating to the progressive failure of rock slopes. Gravity-induced cracks can be distinguished from pre-existing discontinuities for their more irregular profile (zigzag pattern), rougher surface, lower persistence and potentially different orientation. This study also provides some new insights into the step-path failure process of steep rock slopes. The mechanical process of initiation, growing and coalescence of gravity-induced fractures is strongly time- and stress-dependent. In the absence of external changing factors that profoundly modify the acting stress state (for instance, engineering countermeasures), progressive failure is a dynamic and irreversible process. For excavated slopes, the creation of a new rock face may abruptly provide the kinematic freedom of potentially unstable blocks, thus determining a very quick stress redistribution. If the mechanical system is not able to redistribute the stress on resisting stiff parts without overcoming the intact rock strength, gravity-induced cracking initiates and propagates until reaching slope collapse within times that are much shorter (from hours to 100–200 years) compared to natural rock slopes subjected to long-lasting geological processes (from 1000 to 2000 up to 10,000–20,000 years).

A New Gradient-based Feature Extraction Method for Real-time Detection of Moving Objects Using Stereo Cameras

In this study, a gradient-based feature extraction method has been developed that can be used to detect moving objects in real-time applications such as unmanned ground or air vehicles. Feature extraction methods should produce fast results in real-time applications, as results need to be obtained between successive frames of video sequences within a limited time. For this reason, various sized image blocks were used in the developed method. The arithmetic mean (AM), geometric mean (GM), median (MD), and local contrast (LC) methods were used to calculate block intensities. In the stereo video stream, depth maps were also divided into blocks along with successive frames' R, G, and B channels. A novel feature extraction method was developed by calculating gradient-based relationships between adjacent blocks around the centre block. In experimental studies, the features extracted from stereo video frames using the proposed method were compared with Surf, Fast and Brisk methods according to their quantity, accuracy, and processing times, and more successful results were obtained. In addition, the moving object detection performance of the method was tested in real-time using an Unmanned Ground Vehicle.

Bone Region Segmentation in Medical Images Based on Improved Watershed Algorithm.

Watershed algorithm is widely used in image segmentation, but it has oversegmentation in image segmentation. Therefore, an image segmentation algorithm based on K-means and improved watershed algorithm is proposed. Firstly, Gaussian filter is used to denoise human skeleton image. K-means clustering algorithm is used to segment the denoised image and the connected component with the largest area is extracted as the initial human skeleton region. The initial bone region was morphologically opened and then morphologically closed to eliminate the noise. Morphologically open operation is used to disconnect other human tissues that adhere to the human bone region and eliminate the background noise with small area, while closed operation smoothes the edge of the human bone region and fills the fracture in the contour line. Secondly, the watershed segmentation algorithm is implemented on the image after morphological operation. The similarity degree of two blocks is defined according to the mean difference of gray level of adjacent blocks and the mean value of standard deviation of gray level of pixels in the edge of the block 4-neighborhood. The adaptive threshold T is generated by Otsu method for histogram of gradient amplitude image. If the similarity degree is greater than T, the image blocks will be merged; otherwise, the image blocks will not be merged. The proposed image segmentation algorithm is used to extract and segment the human bone region from 100 medical images containing human bone. The number of blocks segmented by watershed algorithm is 2775 to 3357, but the number of blocks segmented by the proposed algorithm is 221 to 559. The experimental results show that the proposed algorithm effectively solves the oversegmentation problem of watershed algorithm and effectively segments the image target.

Numerical modelling of opposing subduction in the Western Mediterranean

The geodynamic evolution of the Western Mediterranean related to the closure of the Ligurian-Tethys ocean is not yet fully resolved. We present a new 3D numerical model of double subduction with opposite polarities fostered by the inherited segmentation of the Ligurian-Tethys margins and rifting system between Iberia and NW Africa. The model is constrained by plate kinematic reconstructions and assumes that both Alboran-Tethys and Algerian-Tethys plate segments are separated by a NW-SE transform zone enabling that subduction polarity changes from SE-dipping in the Alboran-Tethys segment to NW-dipping in the Algerian-Tethys segment. The model starts about late Eocene times at 36.5 Ma and the temporal evolution of the simulation is tied to the geological evolution by comparing the rates of convergence and trench retreat, and the onset and end of opening in the Alboran Basin. Curvature of the Alboran-Tethys slab is imposed by the pinning of its western edge when reaching the end of the transform zone in the adjacent west-Africa continental block. The progressive curvature of the trench explains the observed regional stress reorientation changing from N-S to NW-SE and to E-W in the central and western regions of the Alboran Basin. The increase of the retreat rates from the Alboran-Tethys to the Algerian-Tethys slabs is compatible with the west-to-east transition from continental-to-magmatic-to-oceanic crustal nature and with the massive and partially synchronous calc-alkaline and alkaline magmatism.

Approximation algorithms for sorting by bounded singleton moves

Sorting permutations by block moves is a fundamental combinatorial problem in genome rearrangements. The classic block move operation is called transposition, which switches two adjacent blocks, or equivalently, moves a block to some other position. But large blocks movement rarely occurs during real evolutionary events. A natural restriction of transposition is to bound the length of the blocks to be switched. In this paper, we investigate the problem called sorting by bounded singleton moves, where one of the switched blocks is exactly a singleton while the other is of length at most c. This problem generalizes the sorting by short block moves problem proposed by Heath and Vergara [11], which requires the total length of blocks switched bounded by 3. When c=3, we devise a 95-approximation algorithm for an arbitrary permutation, and a 127-approximation algorithm for a woven double-strip permutation. Our algorithms can be slightly extended to solve the sorting by c-bounded singleton moves problem for any constant c≥3, guaranteeing an approximation factor of 3c5 and 4c7 for arbitrary permutations and woven double-strip permutations respectively, just by exploiting a new lower bound of sorting by c-bounded singleton moves.

Rotational tectonics of the Oregon–Idaho–Montana Cordillera

Paleomagnetic data reviewed along an 800-km transect extending from northeastern Oregon into southwest Montana indicate adjacent crustal blocks experienced post-Jurassic vertical-axis clockwise rotation relative to North America. From west to east, rotated blocks include relict island-arc and related terranes of the Blue Mountains province (Oregon: >60° rotation), calc-alkaline plutons along the arc–continent boundary (Idaho: ~30° rotation), and displaced passive margin strata in the Rocky Mountain foreland (Montana: ≤60° rotation). Assessment of polyphase contractional deformation shows oroclinal bending (~35° westward swing) of the Blue Mountains block concurrent with clockwise turning of the entire terrane province (our variant of conventional model; S.W. Carey, 1955—), with an approximated hinge along the Olympic–Wallowa lineament (~N30W). Restoration of clockwise rotation (~66°; Blue Mountains) reveals collisional mountain-building below a promontory buttress, coeval with torsional displacement on the continental interior.