Margin Region Research Articles

Development of a feature-oriented regional modelling system for the North Brazil Undercurrent region (1°–11°S) and its application to a process study on the genesis of the Potiguar Eddy

ABSTRACT Key elements of a Feature-oriented regional modelling system (FORMS) in the Western Equatorial Atlantic (1°–11°S) are developed for possible application in an operational forecast system as well as in process-oriented studies. This equatorial margin region is dominated by the northwestward flowing near surface North Brazil Undercurrent (NBUC) and the southeastward Deep Western Boundary Current (DWBC). Specifically, we investigate the genesis of a subsurface frontal meander of the NBUC, centred at about 4°S, 36.5°W, called the Potiguar Eddy (PE). The Feature Models (FMs) of NBUC and DWBC are first developed from observed velocity data, with temperature calculated through the thermal wind equation, and salinity from climatology. Two numerical experiments were then set up for the process study, (i) a realistic NBUC + DWBC experiment, with maximum depth of 5500 m, and (ii) a NBUC-only experiment, with maximum depth limited to 1500 m. Results conclude that the PE can be generated by a velocity field containing only the NBUC, and the DWBC – induced vertical shear seems to play a part on the eddy’s baroclinic characteristics (vertical extent and strength). This study highlights the potential of applicability of FORMS for operational forecasts and for process studies in similar regions of the world ocean where currents and topography interact to create permanent and/or semi-permanent eddies.

Variation Characteristics of Stable Isotopes of Precipitation and Water Vapor Sources in the Monsoon Margin Region: A Case Study of the Binggou River Basin

Variation Characteristics of Stable Isotopes of Precipitation and Water Vapor Sources in the Monsoon Margin Region: A Case Study of the Binggou River Basin

ANALYSIS AND INTERPRETATION OF REGIONAL-SCALED GRAVITY MEASUREMENTS IN THE CENTRAL EQUATORIAL ATLANTIC REGION OF AFRICA

Regional-scaled gravity data was interpreted for the Central Equatorial Atlantic African region, a region comprising of both oceanic and continental areas, with a view to understanding more about its complex geological settings and the processes of tectonic evolution. The methods adopted involved the generation of topography/bathymetry, free-air and Bouguer anomaly grids from topography, free-air anomaly and Bouguer anomaly datasets; regional-residual gravity field separation, lineament mapping from the Horizontal Derivative and 2-D modelling of the sub-surface. Within the study area, the elevation ranged from -4,200 to 3,840 m. The free-air anomaly map showed a combination of elongated and circular positive free-air anomalies and elongated, negative free-air anomalies whose values varied between -40 mGal and 70 mGal. The Bouguer anomaly values ranged from -121 to +229 mGal. The Bouguer anomaly map also showed both elongated and circular positive and negative Bouguer anomalies. The dominant orientations of the elongated Bouguer anomalies were the NE-SW, the E-W and the ESE-WNW orientations. Gravity modelling within the oceanic region re- vealed the presence of a basaltic cover whose thickness varied between 1,330 m to 7,700 m in the oceanic and continental margin regions. Associated with the occurrence of this basaltic cover were kinks interpreted as eruption fissures from which the basaltic cover was ejected. It was discovered that the African West Coast Atlantic margin consisted of a trench around the continental margin region adjoined just to the north by some high density basalt, and also that the West African Coastline is heavily laced with magmatism and must have therefore been an active magmatic region in the past. Based on the interpreted data, the study concluded that the Equatorial Atlantic Ocean might have opened on a frame- work of rifts which extended into the inland regions to form the present day sedimentary basins and from the Bouguer anomaly profile along latitude 10oN that it is possible that both the Minna batholith and the Jos Plateau exploited the Proterozoic basement weaknesses for their emplacement.

Expected margin–based pattern selection for support vector machines

Support Vector Machines (SVMs) are amongst the most powerful classification algorithms in machine learning and data mining. However, SVMs are limited by high training complexity when training with large datasets. Pattern selection methods have been proposed to reduce the training complexity by selecting a smaller subset of important patterns among all training patterns. In this paper, we propose a new pattern selection method called Expected Margin–based Pattern Selection (EMPS), which selects patterns based on an estimated margin for SVM classifiers. With the estimated margin, EMPS selects patterns that are likely to become support vectors located on the margin boundary and inside the margin region; however, other patterns including noise support vectors are discarded. The experimental results involving 15 benchmark datasets and one real–world semiconductor manufacturing dataset showed that EMPS exhibits excellent performance and stability.

Experimental investigation of theoretical stability regions for ultra-low frequency oscillations of hydropower generating systems

With the increasing momentum towards flexible power systems based on renewables, the role of hydropower has great importance, especially for providing balancing power. In this paper, a fundamental study on the operating stability of hydropower generating systems is conducted to reveal the practical characteristics for the newly emergent issue of ultra-low frequency oscillations. A unique study methodology is adapted by combing the theoretical analysis and the physical model experiment. In this paper, first, the set-up of the integral experiment platform for the transient processes of the pumped storage plants is presented. Second, a mathematical model of hydropower generating systems is built, and the theoretical stability analysis is conducted based on the Routh-Hurwitz criterion and the stability margin region. The model experiments related to the frequency stability of hydropower generating systems were conducted with reference to the stability region from theoretical analysis. The results demonstrate the sustained ultra-low frequency oscillations and frequency instability of hydropower units in experiments for the first time. Attenuation characteristics of the oscillations are theoretically derived based on the stability margin region, and then quantitatively identified by experiments. The experiment accorded with theoretical stability region within a reasonable tolerance that corresponded to the ±0.1 stability margin.

Origin of ocean island basalts in the West African passive margin without mantle plume involvement

The geochemical variabilities in intraplate basalts (IB) from the West African passive margin (WAPM) region, have generally been employed to indicate the presence of recycled materials in an associated upwelling mantle plume. However, the absence of time-progressive linear hotspot tracks in WAPM-IB make it difficult to explain their genesis solely by the mantle plume hypothesis. Here, we show that the Sr–Nd–Hf–Pb isotopic variations in basalts from most of the WAPM-IB could have mainly attributed to the derivation from two types of fusible regions of the refertilized subcontinental lithospheric mantle (SCLM) and the sub-lithospheric mantle. The locations and magma genesis of WAPM-IB are strongly related to the distance from the Mesozoic rift axis and the structure of the rifted SCLM. The melting of the source region can possibly be attributed to small-scale mantle convection at the base of the SCLM without the involvement of a mantle plume.

Classification of breast mass in mammography using anisotropic diffusion filter by selecting and aggregating morphological and textural features

In this paper, we describe a novel mammogram classification framework for classifying breast tissues as normal, benign or malignant. First, we establish a set of symbolic rules for mammograms pre-classification from the particularities of a tissue (the background, class and severity of abnormality) taking into account the different forms of breast according to their abnormality. A decision tree reflecting a preliminary attribution from the region of interest (ROI) of a mammogram represents this pre-classification. The images obtained by this technique are processed with an anisotropic diffusion filter to reduce the noise and preserve edges. Then, a feature matrix is generated using: on the one hand, textural features from both a Gray Level Co-occurrence Matrix (GLCM) and a Gray Level Run Lengths Matrix (GLRLM) applied to all the filtered regions of interest (ROI) of a mammogram; and on the other, after mass region is segmented out, the features extracted from the mass boundary and the margin region between the mass and background for classification. To derive the relevant features from the feature matrix, we resort to RELIEF and MRMR feature selection method separately. The key point of our proposal is the modeling of Back Propagation Neural Network (BPNN) by a network of queues for representing the textural and morphological properties of the masses. The relevant and ordered features are injected in BPNN classifier using queuing network. The standard database MIAS is used for validation of the proposed scheme. In any case, we observed that the opening of closed neural network improves the performance. However, the MRMR feature selection method outperforms RELIEF one the point of view of precision and area under curve of receiver operating characteristic. These measures are respectively 98.1% and0.9650 for normal vs. abnormal classification, whereas, they are respectively 95.2% and 0.9200 for benign vs. malignant classification.

Two- versus Three-Point Internal Fixation of Displaced Zygomaticomaxillary Complex Fractures.

Despite the high frequency of the zygomaticomaxillary complex (ZMC) fractures, there is no consensus among facial reconstructive surgeons regarding the best surgical management; thus, surgical choice for ZMC fractures is still challenging. This study included 40 patients with displaced ZMC fracture. Twenty patients were treated with open reduction and internal fixation (OR/IF) using two-point fixation technique (at infraorbital margin and zygomaticofrontal buttress region) and the remaining 20 patients were treated with OR/IF using three-point fixation technique (at frontozygomatic suture, infraorbital margin, and zygomatico maxillary buttress). The results of both types of ZMC fractures repair were then statistically compared. No statistical differences between the two types regarding malar eminence asymmetry; projection (forward displacement) and width (medial displacement) in axial CT; inferior displacement; superior displacement and width (medial displacement) in coronal CT; angle of displacement (outward displacement) in 3D CT; masseter and temporalis muscles power electromyography; actual duration of surgery; and patient satisfaction. On the other hand, the total cost of the used plates and screws was significantly higher with three-point repair than two-point repair ( p = 0.003). Moreover, postoperative CT lateral zygoma displacement was statistically significantly better in three-point fixation. Two-point fixation modality for displaced ZMC fractures is as effective as three-point method in fixation and prevents postreduction rotation or clinical displacement with significantly lower cost.

Self-consistent method and steady states of second-order oscillators

The self-consistent method, first introduced by Kuramoto, is a powerful tool for the analysis of the steady states of coupled oscillator networks. For second-order oscillator networks complications to the application of the self-consistent method arise because of the bistable behavior due to the co-existence of a stable fixed point and a stable limit cycle, and the resulting complicated boundary between the corresponding basins of attraction. In this paper, we report on a self-consistent analysis of second-order oscillators which is simpler compared to previous approaches while giving more accurate results in the small inertia regime and close to incoherence. We apply the method to analyze the steady states of coupled second-order oscillators and we introduce the concepts of margin region and scaled inertia. The improved accuracy of the self-consistent method close to incoherence leads to an accurate estimate of the critical coupling corresponding to transitions from incoherence.

Assessing high-intensity focused ultrasound treatment of prostate cancer with hyperpolarized 13 C dual-agent imaging of metabolism and perfusion.

The goal of the study was to establish early hyperpolarized (HP) 13 C MRI metabolic and perfusion changes that predict effective high-intensity focused ultrasound (HIFU) ablation and lead to improved adjuvant treatment of partially treated regions. To accomplish this a combined HP dual-agent (13 C pyruvate and 13 C urea) 13 C MRI/multiparametric 1 H MRI approach was used to measure prostate cancer metabolism and perfusion 3-4h, 1 d, and 5 d after exposure to ablative and sub-lethal doses of HIFU within adenocarcinoma of mouse prostate tumors using a focused ultrasound applicator designed for murine studies. Pathologic and immunohistochemical analysis of the ablated tumor demonstrated fragmented, non-viable cells and vasculature consistent with coagulative necrosis, and a mixture of destroyed tissue and highly proliferative, poorly differentiated tumor cells in tumor tissues exposed to sub-lethal heat doses in the ablative margin. In ablated regions, the intensity of HP 13 C lactate or HP 13 C urea and dynamic contrast-enhanced (DCE) MRI area under the curve images were reduced to the level of background noise by 3-4h after treatment with no recovery by the 5 d time point in either case. In the tissues that received sub-lethal heat dose, there was a significant 60%±12.4% drop in HP 13 C lactate production and a significant 30±13.7% drop in urea perfusion 3-4h after treatment, followed by recovery to baseline by 5 d after treatment. DCE MRI Ktrans showed a similar trend to HP 13 C urea, demonstrating a complete loss of perfusion with no recovery in the ablated region, while having a 40%-50% decrease 3-4h after treatment followed by recovery to baseline values by 5 d in the margin region. The utility of the HP 13 C MR measures of perfusion and metabolism in optimizing focal HIFU, either alone or in combination with adjuvant therapy, deserves further testing in future studies.

Holocene climate evolution in the monsoonal margin region revealed by the pollen record from Jilantai Playa

Holocene climate evolution in the monsoonal margin region revealed by the pollen record from Jilantai Playa

Seismic stratigraphic reconstruction of late Pleistocene lowstand wedges on the shelf margin and trough region of the Korea Strait: a review

This paper is a review of stratigraphic architectures and evolution history of late Pleistocene lowstand deposits on the outer shelf of Korea Strait. Located between the southeastern tip of the Korean Peninsula and the Tsushima Island, the Korea Strait is a seaway connecting the East Sea with the East China Sea. Detailed analysis of high-resolution seismic profiles and sediment data give a good evidence for the existence of three superimposed wedge-shaped sedimentary units that thicken seaward. The individual sedimentary wedges are characterized by seaward dipping and complex sigmoid-oblique prograding reflection configurations with some chaotic or hummocky reflectors. On the basis of distribution and external geometry, these sedimentary wedges are interpreted as a “shelf-margin or shelf-edge delta”, mainly related to falling and lowstand sea level. Occurrence of this delta type is a common constitute of the Quaternary shelf in the Korea Strait. Although the entire units have not been fully dated, it is believed that these wedges were deposited during late Pleistocene sea-level lowstands. Repeated falls and lowstands of sea level (isotopic stages 8, 6 and 2/4) resulted in the formation of lowstand prograding wedges along the present shelf margin and trough region, having been separated from the inner shelf deposits. During subsequent episodes of sea-level rise (isotopic stages 8/7, 6/5, and 2/1), the upper part of sedimentary wedges was eroded, and thin covered by thin transgressive sands. Consequently, the late Pleistocene sequences on the shelf margin and trough region in this area mainly consist of a succession of stacked lowstand prograding wedges formed during the regression and lowstand of sea level.

Pollen evidence for a mid-Holocene East Asian summer monsoon maximum in northern China

There is a controversy regarding whether the high precipitation delivered by an intensified East Asian summer monsoon occurred during the early Holocene, or during the middle Holocene, especially in the context of the monsoonal margin region. The conflicting views on the subject may be caused by chronological uncertainties and ambiguities in the interpretation of different climate proxies measured in different sedimentary sequences. Here, we present a detailed record of the Holocene evolution of vegetation in northern China based on a high-resolution pollen record from Dali Lake, located near the modern summer monsoon limit. From 12,000–8300 cal BP, the sandy land landscape changed from desert to open elm forest and shrubland, while dry steppe dominated the hilly lands and patches of birch forest developed in the mountains. Between 8300 and 6000 cal BP, elm forest was extensively distributed in the sandy lands, while typical steppe covered the hilly lands and mixed coniferous–broadleaved forests expanded in the mountains. Our pollen evidence contradicts the view that the monsoonal rainfall increased during the early Holocene; rather, it indicates that the East Asian summer monsoon did not become intensified until ∼8000 cal BP in northern China. The low precipitation during the early Holocene can be attributed to the boundary conditions, i.e., to the remnant high-latitude Northern Hemisphere ice sheets and the relatively low global sea level.

A clustering algorithm using skewness-based boundary detection

Abstract Clustering analysis has been applied in all aspects of data mining. Density-based and grid-based clustering algorithms are used to form clusters from the core points or dense grids to extend to the boundary of the clusters. However, deficiencies are still existed. To find out the right boundary and improve the precision of the cluster, this paper has proposed a new clustering algorithm (named C-USB) based on the skew characteristic of the data distribution in the cluster margin region. The boundary degree calculated by skew degree and the local density are used to distinguish whether a data is an internal point or non-internal point. And the connected matrix is constructed by removing the neighbor relationships of non-internal points from the relationships of all points, then the clusters can be formed by searching from the connected matrix towards internal of the clusters. Experimental results on synthetic and real data sets show that the C-USB has higher accuracy than that of similar algorithms.

Programmed cell death-ligand 1 expression and immunoscore in stage II and III non-small cell lung cancer patients receiving adjuvant chemotherapy.

Programmed cell death 1 (PD-1) receptor–ligand interaction is a major pathway that is often hijacked by tumors to suppress immune control. Immunoscore (IS), a combinational index of CD3 and CD8 tumor-infiltrating lymphocyte (TIL) density in the tumor’s center and invasive margin, is a new prognostic tool suggested to be superior to conventional tumor-staging methods in various tumors. This retrospective study aimed to investigate the prevalence and prognostic roles of PD-ligand 1 (PD-L1) expression and IS in non-small cell lung cancer (NSCLC) patients receiving adjuvant chemotherapy. PD-L1 expression and TIL density were evaluated by immunohistochemical analysis in 36 patients with stage II and III NSCLC. Tumors with staining in over 1% of their cells were scored as positive for PD-L1 expression, and we determined the median number of CD3- and CD8-positive TILs as the cutoff point for TIL density. To determine IS, each patient was given a binary score (0 for low and 1 for high) for CD3 and CD8 density in both the tumor center and invasive margin region. PD-L1 expression in tumor cells was observed in 61.1% (22/36) of patients. PD-L1 expression was significantly associated with high IS, and highest IS tended to have a favorable disease-free survival.

Specific Location of Disc Hemorrhage is Linked to Nerve Fiber Layer Defects.

To investigate the relationship between retinal nerve fiber layer (RNFL) defects and the quadrant and proximal location of disc hemorrhages (DHs) in a large population examined for health screening. A total of 168,044 subjects older than 20 years underwent a single screening ophthalmic examination with color fundus photography as part of a comprehensive health screening program. The presence and location of DHs and RNFL defects were assessed. The DH locations were defined according to the quadrant location (inferotemporal, superotemporal, inferonasal, or superonasal) and the most proximal end of DHs relative to the disc center (cup base, cup margin, disc rim, or extrapapillary region). Using these two location descriptors as independent variables, a logistic regression analysis was conducted to explore the effects of DH location on RNFL defects. Two hundred twenty-six eyes had DH and 120 (53.1%) of them had RNFL defects. After adjusting for proximal location, DHs located in the inferotemporal quadrant accompanied RFNL defects 12 times more frequently than those in the superonasal quadrant (odds ratio [OR], 11.81; P = .004). Conversely, after adjusting for quadrant location, the ORs for an associated RNFL defect were 3.73 (P < .001), 16.54 (P < .001), and 8.91 (P = .002) for DHs with the proximal end at the disc rim, cup margin, and cup base, respectively. Among the four quadrants and four proximal locations, DHs were identified most frequently in the inferotemporal quadrant and outside the disc, respectively. Some DH locations, such as the inferotemporal quadrant and the cup margin, were associated with RNFL defects, whereas others were not.

Relationship Between Femur and Femoral Arteries for Identifying Risk Factors for Vascular Injury.

BackgroundThis study aimed to identify risk factors for vascular injury in proximal femoral fracture through identifying frequency and distances between femur and femoral arteries with computed tomography angiography and 3-dimensional reconstruction.Material/MethodsIn a series of 400 participants, based on measurement results regarding the distribution of femoral arteries in the medial femur, the femoral portion covering that part was divided into levels A–E. The center region, margin region, and risky area in the medial femur were defined. The frequency of femoral arteries and interested shortest distance between the outer femur and superficial, deep, and perforating femoral arteries (SFAs, DFAs, and PFAs) in the center region, margin region, and risky area at each level were recorded.ResultsThere were 173 males and 227 females (average age: 63.61±19.18 years) in this study. The starting point and end point for femoral arteries in the medial femur were from 22.55±4.23% to 54.56±8.39% of the whole femur. The femoral arteries in the medial femur mainly were distributed at levels B (88.2%), C (65.9%), and D (40.6%). The femoral arteries in center regions in the risky area, most of which were DFAs and PFAs, were mainly concentrated at levels B (26.93%) and C (11.81%).ConclusionsThe mid-shaft level was the most risky level, and the DFAs and PFAs were easier to injure than the SFAs when performing internal fixation of proximal femoral fracture. We recommended that great attention be paid to drill and screw insertion around the mid-shaft level for prevention of iatrogenic vascular injury.

Identification of five Pampus species from the coast of China based on sagittal otolith morphology analysis

Sagittal otoliths morphology were compared to identify five Pampus species of the Chinese coast (Chinese pomfret Pampus chinensis, grey pomfret P. cinereus, southern lesser pomfret P. minor, plumage pomfret P. punctatissmus, and Pampus sp.). Otoliths demonstrated species-specific characteristics with noticeable differences in overall shape, margin and anterior region among species. With species divergence, otoliths get thinner following further developed rostrum and anti-rostrum. Interspecies variation in otolith could associate with experienced different temperature and water column. The discriminant analysis presented a high classification accuracy of 96.6%, which confirms the inter-specific distinction of otolith shape and enable the species identification.

A preliminary study of a sediment core drilled from the mud area on the inner shelf of the East China Sea: Implications for paleoclimatic changes during the fast transgression period (13 ka B.P.–8 ka B.P.)

A 35.30 m-long core (MZ02) that was recovered from a water depth of 32.4 m from the inner shelf mud deposit of the East China Sea is analyzed to determine its sedimentary characteristics, color reflectance, clay mineral content, element geochemistry components and AMS 14C dating to investigate the sedimentation rate, sediment provenance and paleoclimate evolution during the fast transgression period. Rare earth element and clay mineral proxies indicate that mixed-provenance sediment accumulated in the foreshore–nearshore region at the beginning of the fast transgression period, with a higher sedimentation rate of 5.58 m/ka. From the early Holocene (9.8–9.5 ka B.P.), the sedimentation rate declined by approximately 1.73 m/ka, and the sediment provenance obviously changed. The silt fraction resembled that of Taiwan's mountainous rivers and the clay fraction was primarily transported from the Yangtze River. A multiple proxy system including sediment redness (a*), chemical index of alteration (CIA), clay mineral ratio (smectite/kaolinite), and major and trace element ratios (CaO/MgO, Ba/Sr), also provides a good paleoclimate record during the fast transgression period, which can be divided into three units. All the proxies barely changed during Unit I (12.88–10.85 ka B.P.), revealing that the climate remained relatively stable. Obvious fluctuations occurred during Unit II (10.85–10.05 ka B.P.), and the temperature kept decreasing for more than 1 ka until the Younger Dryas event, showing a notable regional response to global climate changes. A continuous warming trend resumed again during Unit III (10.05–8.15 ka B.P.), which may mark the threshold of the Holocene warm period. In addition, we find significant 80-yr, 89-yr and 100-yr cycles in the CIA, CaO/MgO and Ba/Sr records, which imply the possible influence of solar activity on regional climate change during the fast transgression period in the Asian margin region.

Optical transparency radial distribution of ion thruster

The optical system is one of the main components of an ion thruster, which consists of electrically biased multi-aperture grids. The grid design is critical to the ion thruster operation since its transparency has an important influence on the thruster efficiency and thrust. To further optimize the optical system performance and evaluate effectively the efficiency of ion thruster, the optical transparency radial distribution of ion thruster is analyzed and discussed in experiment and simulation. The process of beam extraction is simulated by the particleincell-Monte Carlo collision (PIC-MCC) method, and the movement of the ions is investigated by the PIC method while the collisions of particles are handled by the MCC method. Then the interdependency among the transparency of screen grid, the accelerator grid, optics system and the number of ion extracted is analyzed. Taking into account the distribution of ion density at the exit of discharge chamber, the radial distribution of the screen grid transparency, accelerator grid transparency and optical system transparency are acquired. An experiment is performed to verify the simulation based derivation, indicating the good agreement between experimental and simulation results. The results show that the radial distribution of screen grid transparency increases gradually along the radial direction and has a good central axial symmetry, and its minimum value is located in the center of the thruster while the maximum value is near the margin region of screen gird. The radial distribution of accelerator grid transparency is opposite to that of the screen grid transparency, which decreases along the radial direction, and its maximum value is located at the axis of the thruster. The radial distribution of optical system transparency is the same as that of the screen grid transparency. And its minimum value is in the center of optics system, which indicates that the effect of accelerator grid transparency on the optical system transparency is little. In addition, the study also finds that the total optical transparency of ion thruster decreases slowly as the beam current increases. This work will provide a lot of support for the optimal design of ion thruster optics system.