Central Segment Research Articles

Role of interhemispheric connectivity in recovery from postoperative supplementary motor area syndrome in glioma patients.

Surgical resection of gliomas involving the supplementary motor area (SMA) frequently results in SMA syndrome, a symptom complex characterized by transient akinesia and mutism. Because the factors influencing patient functional outcomes after surgery remain elusive, the authors investigated network-based predictors in a multicentric cohort of glioma patients. The participants were 50 patients treated for glioma located in the SMA at one of the three centers participating in the study. Postoperative functional outcomes (motor deficits, mutism) and duration of symptoms were assessed during hospitalization. Long-term outcome was assessed 3 months after surgery. MRI-based lesion-symptom mapping was performed to estimate the severity of gray matter damage and white matter disconnection. The median duration of acute symptoms was 3 days (range 1-42 days). Long-term deficits involving fine motor movements and speech were found at follow-up in 27 patients (54%). Disconnection of the central callosal fibers was associated with prolonged acute symptoms (p < 0.05). Postoperative mutism was significantly related to disconnection severity of the left frontopontine tract, frontal aslant tract, cingulum, and corticostriatal tract (p < 0.05). Disconnection of midposterior callosal fibers and lesion loads within the left medial Brodmann area 4 were associated with long-term motor deficits (p < 0.05). This study provides evidence for the pathophysiology and predictive factors of postoperative SMA syndrome by demonstrating the relation of the disconnection of callosal fibers with prolonged symptom duration (central segment) and long-term motor deficits (midposterior segment). These data may be useful for presurgical risk assessment and adequate consultation for patients prior to undergoing resection of glioma located within the SMA region.

Extension Magnitude and Ratio of Central and South Segments in South Atlantic Margins

Extension Magnitude and Ratio of Central and South Segments in South Atlantic Margins

Mechanism of Structure Variations at Rifted Margins in the Central Segment of South Atlantic: Insights from Numerical Modeling

AbstractRifted margins in the central South Atlantic portray spatial variability in terms of preserved width and thickness, which relates to complex rift‐related fault activities. However, there is still a lack of systematic and quantitative explanations for the causes of the variations that are observed along the paired rifts. To elucidate this issue, 2D viscous‐plastic thermomechanical numerical models are applied to capture the behavior of deformation, in which we investigate the effects of extensional rate, crustal strength and thickness on crust‐mantle coupling, and timing of transition from rifting to breakup. Our numerical experiments demonstrate that crust‐mantle decoupling accounts for crustal hyperextension, and that incorporating moderate‐intensity rheology into lower crust may yield insights into the hyper‐extended crust and asymmetric architecture observed in the central South Atlantic. The results also suggest that undulations in lithospheric basement cause asymmetric mantle upwelling. The lower crust of fold belts takes priority to be thermally weakened over craton and induces rift migration simultaneously. A new mechanism for the formation of failed rift is described, where the mechanical decoupling derived from thermally weakened lower crust gives access to dual rift migration. These results reinforce the interpretation on how crustal rheology shapes margins architectures and highlight the first‐order effects of crust‐mantle coupling.

A Novel Strategy of US3 Codon De-Optimization for Construction of an Attenuated Pseudorabies Virus against High Virulent Chinese Pseudorabies Virus Variant.

In this study, we applied bacterial artificial chromosome (BAC) technology with PRVΔTK/gE/gI as the base material to replace the first, central, and terminal segments of the US3 gene with codon-deoptimized fragments via two-step Red-mediated recombination in E. coli GS1783 cells. The three constructed BACs were co-transfected with gI and part of gE fragments carrying homologous sequences (gI+gE'), respectively, in swine testicular cells. These three recombinant viruses with US3 codon de-optimization ((PRVΔTK&gE-US3deop-1, PRVΔTK&gE-US3deop-2, and PRVΔTK&gE-US3deop-3) were obtained and purified. These three recombinant viruses exhibited similar growth kinetics to the parental AH02LA strain, stably retained the deletion of TK and gE gene fragments, and stably inherited the recoded US3. Mice were inoculated intraperitoneally with the three recombinant viruses or control virus PRVΔTK&gEAH02 at a 107.0 TCID50 dose. Mice immunized with PRVΔTK&gE-US3deop-1 did not develop clinical signs and had a decreased virus load and attenuated pathological changes in the lungs and brain compared to the control group. Moreover, immunized mice were challenged with 100 LD50 of the AH02LA strain, and PRVΔTK&gE-US3deop-1 provided similar protection to that of the control virus PRVΔTK&gEAH02. Finally, PRVΔTK&gE-US3deop-1 was injected intramuscularly into 1-day-old PRV-negative piglets at a dose of 106.0 TCID50. Immunized piglets showed only slight temperature reactions and mild clinical signs. However, high levels of seroneutralizing antibody were produced at 14 and 21 days post-immunization. In addition, the immunization of PRVΔTK&gE-US3deop-1 at a dose of 105.0 TCID50 provided complete clinical protection and prevented virus shedding in piglets challenged by 106.5 TCID50 of the PRV AH02LA variant at 1 week post immunization. Together, these findings suggest that PRVΔTK&gE-US3deop-1 displays great potential as a vaccine candidate.

Diagnostic Value of Contrast-Enhanced Ultrasonography for Catheter-Related Right Brachiocephalic Vein and Superior Vena Cava Lesions in Patients Undergoing Hemodialysis-A Pilot Study.

To evaluate the diagnostic efficacy of contrast-enhanced ultrasonography (CEUS) for detecting catheter-related right brachiocephalic vein (RBV) and superior vena cava (SVC) obstructions in patients undergoing hemodialysis (HD). From June 1, 2021 to December 31, 2022, we enrolled 80 patients undergoing HD who had used or were using a central venous catheter as vascular access. We evaluated the diagnostic efficacy of conventional ultrasonography and CEUS for identifying RBV and SVC obstructions and compared them with that of digital subtraction angiography (DSA). In the stratified analysis, the SVC was divided into the upper and lower segments. In total, we analyzed 240 central venous segments, including the RBV. Among the RBV and SVC visualized by DSA, conventional ultrasonography and CEUS could visualize 67.92 and 100% of the vein segments, respectively; however, the lengths and diameters of the RBV and SVC were smaller than those recorded with DSA (P < .001). The diagnostic efficacy of CEUS for detecting catheter-related central venous obstruction was better than that of conventional ultrasonography, with a higher sensitivity (83.95 vs 41.98%), specificity (89.94 vs 53.46%), accuracy (87.92 vs 49.58%), and F1 score (82.42 vs 49.64%). CEUS showed good agreement (κ = 0.732) with DSA. In the stratified analyses, CEUS also showed higher sensitivity (83.93, 83.33, and 84.62%, respectively) and better agreement with DSA (κ = 0.635, 0.655, and 0.673, respectively) than conventional ultrasonography for detecting the RBV and the upper and lower segments of the SVC. CEUS had high sensitivity and specificity in diagnosing catheter-related RBV and SVC obstructions.

Along-strike segmentation of the northeastern Brazilian margins controlled by geodynamics and lithospheric inheritance

Passive continental margins depict a wide range of crustal architectures. Such observation mainly come from wide-angle seismic that has proven to be a valuable tool to constrain margins’ onshore and offshore crustal structures. Yet, it is still unclear what are the main drivers of such diversity and whether some more general processes do also control their formation. Here, by analyzing coincident marine seismic reflection and refraction data acquired parallel to the coast of northeast Brazil we shed a unique view on the along-strike segmentation of its passive margins. Our two P-wave velocity models add up to 10 other wide-angle velocity models build in the scope of the SALSA (Sergipe ALagoas Seismic Acquisition) project to provide a coherent picture of the crustal and upper mantle architecture of the offshore domains of the Jequitinhonha, Almada, Camamu, Jacuípe, Sergipe and Alagoas margins. In the Camamu-Jacuípe segment, both crustal necking and the continent to ocean transition were shown to be sharp. Along strike, our models show extremely thin crust above a thick anomalous velocity layer and a relatively low density mantle. This architecture is interpreted as made of collapsed continental blocks above either highly intruded lower continental crust and/or serpentinized mantle that is locally exhumed. It greatly differs from the crustal structure imaged to the south, within the Jequitinhonha and Almada segments, where our models support the existence of a vast and homogeneous domain of exhumed lower continental crust. It also considerably contrasts with the offshore architecture of the Sergipe-Alagoas segment to the north. There, the necking and transition to normal oceanic crust was shown to be narrow but gradual and dominated by middle to lower continental crust. On our along-strike models, it is characterized by a thicker but also highly intruded continental crust. Crustal architecture evolves brutally at the frontiers of these segments which coincides precisely with the Camamu Triple Junction and the offshore prolongation of the Vaza Barris fault zone. The former is one of the major geodynamic features in the development of the Central Segment of the South-Atlantic Ocean while the later marks the suture between the São-Francisco Craton and the northeastern Brazilian Orogenic Belt. Therefore, we clearly evidence the first-order control of both geodynamics and lithospheric inheritance on the along-strike segmentation of the northeastern Brazilian passive margins. Our results emphasize the crucial role of plate kinematics and lithospheric strength in shaping their architectures and the exhumation of middle/lower continental crust as a more general process of their formation.

Alteration-mineralization zonality of the Teploe 2 and Intruzivnoe molybdenum prospects in the Djetsky ore cluster, Eastern Sayan

Molybdenum mineralization in the Eastern Sayan is represented by the stockwork, vein, and skarn types. The article is devoted to molybdenum ore occurrences of the Dzhetsky ore cluster of the Sisim-Divnogorsk minerogenic zone, that are characterized by the stockwork type mineralization. The Dzhetsky ore cluster is located 160 km northeast of Abakan and 150 km south of Krasnoyarsk. The study included investigations of the host rocks, ores, and ore-accompanying metasomatic alterations; their mineral assemblages; and the morphological types, relationships, and spatial distribution of the ore segregations. It has been demonstrated that the alteration-mineralization zonality of the Teploe 2 and Intrusivnoe molybdenum prospects of the Dzhetsky ore cluster is represented by the propylite type metasomatic alterations that are superimposed in the central segments of the ore occurrences by veinlet silicification bearing copper-molybdenum mineralization.

Present–day crustal deformation in the southeastern Tibetan Plateau: Insights from three–dimensional finite–element modeling

Quantifying the present–day kinematics of southeastern Tibet is important for understanding the tectonic evolution of the Tibetan Plateau. In this study, we established a three–dimensional finite element model to estimate fault slip and strain rates in the southeastern Tibetan Plateau based on Global Navigation Satellite Systems (GNSS) observations. Our model yields an overall good fit to the GNSS velocity field with residuals of 0.83 mm/yr and 0.85 mm/yr for the east and north components, respectively, comparable to the uncertainties of 0.67 mm/yr and 0.61 mm/yr. The model–derived strike–slip rates of the Xiaojiang fault, Nanhua–Chuxiong fault, Qujiang fault, central segment of Red River fault, southeastern segment of Red River fault and Dien Bien Phu fault are 13.7 ± 0.7 mm/yr, 1.9 ± 0.6 mm/yr, 3.4 ± 1.1 mm/yr, 1.5 ± 0.5 mm/yr, 1.2 ± 0.4 mm/yr and 1.6 ± 0.4 mm/yr, respectively, which are consistent with previous geological results, implying that the short–term fault motions estimated from GNSS data can reflect the long–term fault slip in the southeastern Tibetan Plateau. The shear strain rate is localized along the Xiaojiang fault, which agrees with predictions of the tectonic extrusion model (i.e., the lateral extrusion of internally rigid blocks along strike-slip faults). Strain orientations in the western part of southeastern Tibetan Plateau are characterized by clockwise rotation. Comparison of the surface strain rates, crustal stress, and seismic anisotropy reveals general consistency between deformation of the surface and upper crust. The eastern part of southeastern Tibetan Plateau has small residuals, and the present–day crustal deformation can be explained by rigid block motion. However, the western part of the study area has relatively large residuals, implying that other processes, such as gravitational spreading, may influence deformation in the area. We propose a hybrid model that combines rigid block motion with continuum deformation to explain the contemporary crustal deformation of southeastern Tibetan Plateau.

Stenosis Detection and Quantification of Coronary Artery Using Machine Learning and Deep Learning.

The aim of this review is to introduce some applications of artificial intelligence (AI) algorithms for the detection and quantification of coronary stenosis using computed tomography angiography (CTA). The realization of automatic/semi-automatic stenosis detection and quantification includes the following steps: vessel central axis extraction, vessel segmentation, stenosis detection, and quantification. Many new AI techniques, such as machine learning and deep learning, have been widely used in medical image segmentation and stenosis detection. This review also summarizes the recent progress regarding coronary stenosis detection and quantification, and discusses the development trends in this field. Through evaluation and comparison, researchers can better understand the research frontier in related fields, compare the advantages and disadvantages of various methods, and better optimize the new technologies. Machine learning and deep learning will promote the process of automatic detection and quantification of coronary artery stenosis. However, the machine learning and the deep learning methods need a large amount of data, so they also face some challenges because of the lack of professional image annotations (manually add labels by experts).

Limited Northward Expansion of the Tibetan Plateau in the Late Cenozoic: Insights From the Cherchen Fault in the Southeastern Tarim Basin

AbstractThe northern margin of the Tibetan Plateau is defined by the left‐lateral Altyn Tagh fault. It remains unclear whether the Cenozoic deformation related to the India‐Asia collision has remained stationary along the Altyn Tagh fault or propagated northward into the southeastern Tarim Basin. The Cenozoic Cherchen fault is located in the southeastern Tarim Basin, ∼90–120 km north of the Altyn Tagh fault, and thus, may play a critical role in addressing this issue. Here, we used a densely‐spaced two‐dimensional seismic reflection survey to investigate the geometry and kinematics of the Cherchen fault and understand its role in the expansion of the northern margin of the Tibetan Plateau. Our seismic study shows that the Cenozoic Cherchen fault is a high‐angle left‐lateral transpressional fault. Kinematic analysis of the Cherchen fault suggests that a restraining bend structure has formed along its central segment. Stratigraphic records suggest that the Cherchen fault initiated in the Paleozoic and reactivated during the middle Miocene (ca. 17–15.7 Ma). We infer that the dip‐slip and strike‐slip rates of the Cherchen fault are ∼0.09 mm/a and ∼1.66 mm/a, respectively. A regional cross section reveals that the northward expansion of the plateau is ongoing, but the range is limited to ∼90–120 km. We interpret that middle Miocene tectonic activity throughout the region was also concentrated along the northern plateau margin, defined by both northeast‐directed crustal shortening and northward expansion of the plateau.

The February 6, 2023, Earthquakes in Turkey: A Model of the Rupture Surface Based on Satellite Radar Interferometry

Two strike–slip faults, displacements along which caused the catastrophic earthquakes in Turkey on February 6, 2023, were mapped from satellite radar interferometry data. According to the satellite data, the relative displacements of the sides of the East Anatolian Fault Zone (EAFZ), with which the first event of Mw 7.8 was associated, exceeded 5 m in the central segment. The rupture surface extends from the area of the Doğanyol-Sivris earthquake Mw 6.7 of January 24, 2020, in the north to the Mediterranean coast in the south, where the earthquake Mw 6.3 occurred on February 20, 2023. The second event Mw 7.5 is associated with the Surgü-Çardak fault; the relative displacements of its sides, according to satellite data, exceeded 7 m. The obtained displacement fields of the Earth’s surface were used to construct a model of the seismic rupture. This model was worked out on the basis of the Pollitz, 1996 solution, which defines displacements on the surface of the spherically stratified planet as a result of along dip and strike displacements on a rectangular rupture located inside the sphere. Ignoring the spherical stratification of the planet leads to errors of up to 20%, especially in the presence of a large strike–slip component [5]. Ignoring sphericity also causes an error, when using the solution obtained for an elastic homogeneous half-space, as the US Geological Survey (USGS) has done, in modeling the seismic rupture for earthquakes in Turkey in 2023. Our model differs in the detailed consideration of the fault geometry. For this purpose, the faults were approximated by 19 planes along the strike, divided into two levels along the dip. In our rupture model strike–slip displacements in the central segment of the EAFZ reached 12.7 m. In the southern segment of this rupture, the displacements are much smaller. It should be emphasized that we registered the displacements for the period from January 29, 2023, to February 10, 2023; therefore, together with co-seismic ones, they also include post-seismic displacements for four days after the main seismic events. The displacements on the rupture surface along the Surgü-Çardak Fault, where the Mw 7.5 earthquake occurred, were up to 10 m. The results demonstrate, in particular, the efficiency of application of the satellite radar interferometry in the operative study of catastrophic geodynamic phenomena and processes.

EARTHQUAKES IN TURKEY 06.02.2023: MODEL OF THE RUPTURE SURFACE BASED ON SATELLITE RADAR INTERFEROMETRY

Satellite radar interferometry data made it possible to clearly map two faults, shear displacements along which caused catastrophic earthquakes on February 06, 2023 in Turkey. According to satellite data, the relative displacements of the sides of the East Anatolian Fault Zone (EAFZ), to which the first event with a magnitude of Mw 7.8 was associated, exceeded 5 m in the central segment. The rupture surface extends from the area of the Doğanyol-Sivris of 24.01.2020 Mw 6.7 earthquake in the north to the Mediterranean coast in the south, where the earthquake Mw 6.3 occurred on 20.02.2023. The second event of Mw 7.5 is associated with the Surgü-Çardak fault, and the relative displacements of its sides, according to satellite data, exceeded 7 m. The obtained displacement fields of the Earth’s surface were used to construct a model of the seismic rupture. The model is based on the solution [5], which defines displacements on the surface of a spherically stratified planet as a result of dip and strike displacements on a rectangular rupture located inside the sphere. Ignoring the spherical stratification of the planet leads to errors of up to 20%, especially in the presence of a large shear component [5]. Also, an error is introduced by ignoring sphericity when using the solution obtained for an elastic homogeneous half-space [6], as the US Geological Survey (USGS) did when building seismic rupture models for earthquakes in Turkey in 2023. The difference of our model is the detailed consideration of the fault geometry. For this purpose, the faults were approximated by 19 planes along the strike, divided into two levels along the dip. In the built model, shear displacements in the central segment of the EAFZ reached 12.7 m. In the southern segment of this rupture, the displacements are substantially smaller. It should be emphasized that we registered the displacements for the period from January 29 to February 10, 2023, i.e. together with coseismic ones, they also include postseismic displacements for 4 days after the main seismic events. The displacements on the rupture surface along the Surgü-Çardak fault, where an Mw 7.5 earthquake occurred, reached 10 m. The obtained results demonstrate, in particular, the efficiency of application of satellite radar interferometry in the operative study of catastrophic geodynamic phenomena and processes.

Geometric morphometrics and phylogenetic analysis of Delphinium taxa from south of Russia

The leaf blade’s shape of 665 samples of 18 taxa from the genus Delphinium was analyzed using geometric morphometrics method. Within the subgenus Delphinastrum, D. elatum and, to a lesser extent, D. uralense were relatively well separated by canonical analysis, while D. litwinowii, D. pubiflorum, D. duhmbergii, and D. subcuneatumwere not actually separated. Within the subgenus Oligophyllon, D. caucasicum was well separated by this method. The scatter clouds of D. freynii + D. puniceum + D. sergii on the one hand, and D. fedorovii + D. gelmetzicum on the other hand, also separated. D. arcuatum, D. bracteosum, D. crispulum, D. flexuosum, and D. mariae did not separate from each other. The nature of such separation of species groups observed in the space of canonical variables and their relative proximity to each other can be associated with the habitat similarity of their populations driven by ecological or geographical conditions, as well as the influence of hybridization processes in the zone of secondary contact of species. The differences in leaf blade’s shape are mainly related to the width of the segments, the lengths of the central segment of the middle lobe and the undissected part of the leaf blade, the degree of its dissection, the shape of the base and the distance between the lower lobes. Based on the results of DNA sequencing of the intergenic transcribed spacer ITS2, the taxonomic independence of D. puniceum, D. macropogon, D. mariae, D. samurense, and D. pubiflorum is beyond any doubt. The synonymy of D. freynii and D. sergii is supported, with the priority name of D. schmalhausenii. D. cuneatum, D. subcuneatum, D. duhmbergii, and D. litwinowii should be considered as synonyms with the priority name of D. cuneatum. The taxonomic status of D. dictyocarpum, D. elatum, and D. uralense needs further clarification. This is probably related to their easy hybridization with D. cuneatum in sympatric populations within the overlapping areas. Delphinium arcuatum, D. bracteosum, D. caucasicum, D. crispulum, D. elisabethae, D. fedorovii, D. flexuosum, D. gelmetzicum, and D. speciosum are poorly separated, which can also be associated with hybridization processes. They need to be studied in more detail.

Geochemistry, zircon U–Pb geochronology and Hf isotope of the early Permian gabbro and high-Mg diorites from the Zhusileng–Hangwula Belt in the northern Alxa area: Petrogenesis and tectonic implications

AbstractAs the southernmost part of the central segment of the Central Asian Orogenic Belt, the northern Alxa area is characterized by abundant Permian magmatism and records key information on the geological evolution of the Palaeo-Asian Ocean. This study reports new zircon U–Pb and Lu–Hf isotopic and whole-rock geochemical data of the early Permian (285–286 Ma) Huisentala gabbro and Huodonghaer diorites from the Zhusileng–Hangwula Belt in the northern Alxa area. The gabbro is characterized by high Al, Ca, Mg# and light rare-earth elements, and low K, P and high field strength elements (e.g., Ti, Nb and Ta). Furthermore, the gabbro shows heterogeneous zircon ϵHf(t) value (−2.5 to +2.6). The Huodonghaer diorites show high MgO (3.46–6.32 wt%), Mg# (49–58), Sr (408–617 ppm) and Ba (223–419 ppm), and low FeOT/MgO (1.27–1.83) and TiO2 (0.48–0.90 wt%), with geochemical features similar to the high-Mg andesite/diorite. They show radiogenic zircon ϵHf(t) values of +1.2 to +4.9 and high Th/Nb ratios. These features suggest that the Huisentala gabbro and the Huodonghaer diorites were derived from the partial melting of mantle peridotite that was metasomatized by subduction-related fluids and by subducted sediment-derived melts, respectively.

Insights on the Interplay of Rifting, Transcrustal Magmatism and Formation of Geothermal Resources in the Central Segment of the Ethiopian Rift Revealed by 3‐D Magnetotelluric Imaging

AbstractThe Main Ethiopian Rift is accompanied by extensive volcanism and the formation of geothermal systems, both having a direct impact on the lives of millions of inhabitants. Although previous studies in the region found evidence that asthenospheric upwelling and associated decompression melting provide melt to magmatic systems that feed the tectono‐magmatic segments in the rift valley, there is a lack of geophysical models imaging these regional and local scale transcrustal structures. To address this challenge, we use the magnetotelluric method and image subsurface electrical conductivity to examine the magmatic roots of Aluto volcano, quantify and interpret the melt distribution in the crust considering established concepts of continental rifting processes and constrain the formed geothermal system. Specifically, we combined regional (maximum 30 × 120 km2) and local (15 × 15 km2) magnetotelluric data sets and obtained the first multi‐scale 3‐D electrical conductivity model of a segment of the central Main Ethiopian Rift. The model unravels a magma ponding zone with up to 7 vol. % melt at the base of the crust (30–35 km b.s.l.) in the western part of the rift and its connection to Aluto volcano via a fault‐aligned transcrustal magma system. Melt accumulates at shallow crustal depths (≥4 km b.s.l.), thereby providing heat for Aluto's geothermal system. Our model suggests that different volcano‐tectonic lineaments in the rift valley share a common melt source. The presented model provides new constraints on the melt distribution below a segment of the rift which is important for future geothermal developments and volcanic hazard assessments in the region.

The distribution characteristics of heavy metal contamination in the central segment of Xiaonan River, Shenyang

&lt;p&gt;The middle segment of Xiaonan River, which feeds into the Puhe River, was chosen for research. Samples including its water, river bottom mud, river bank soil, and nearby vegetation were collected from six monitoring sites. These samples were analyzed by ICP-OES to determine heavy metal distribution. The results showed that main contamination of heavy metals in the Xiaonan River are Cd, Cr, Cu, Ni, Pb, and Zn. Notably, Cr and Zn are in high levels, and Cr surpassed the limit of third-grade standard, indicating severe contamination. By using the potential ecological risk index method, Cd showed a high coefficient, severely damaging the surface water and riparian soil. The migration patterns of Cr and Zn were different. Cr tended to accumulate more in riverbank soils, while Zn showed higher concentrations in river bottom mud. Plants of nearby vegetation showed minimal absorption and transfer capabilities for Cd, while Ni transferred most. By applying the ecological risk index, potential pollution sources were inferred to assess each metal's distribution, so to offer a basis from its origin, and to protect the ecological health of the Puhe River Basin.&lt;/p&gt;

Sural communicating nerve for application as a vascularized nerve graft: A microneurovascular anatomic study in cadavers.

Sural nerve harvest causes paraesthesia to the lateral heel of the foot, which can debilitate those with already compromised proprioception. To circumvent this, we investigated an alternative donor nerve, branch of the lateral sural nerve complex called the sural communicating nerve (SCoNe), for its harvest and use as a vascularized nerve graft, in cadaver. The SCoNe was visualized by dissection in 15 legs from 8 human cadavers and the relationship of the SCoNe to the overall sural nerve complex was documented. The surface markings, dimensions, and the micro-neurovascular anatomy in the super-microsurgery range (up to 0.30 mm) of the SCoNe was recorded and analyzed. SCoNe graft surface marking was confined within a triangle drawn between the fibular head laterally, the popliteal vertical midline medially and the tip of the lateral malleolus inferiorly. The proximal end of the SCoNe was situated at a mean intersection distance of 5 cm from both the fibular head and popliteal midline respectively. The mean length of the SCoNe was 226 ± 43 mm with a mean proximal diameter of 0.82 mm and mean distal diameter of 0.93 mm. In 53% of the cadavers, an arterial input was present in the proximal third of the SCoNe and veins were predominantly (87%) present in the distal third. In 46% and 20% of the 15 legs respectively, there was a nutrient artery and vein perfusing the SCoNe in its central segment. The external mean diameter of this artery was 0.60 ± 0.30 mm, while the vein was slightly larger with a mean diameter of 0.90 ± 0.50 mm. SCoNe graft may preserve lateral heel sensation, compared to sural nerve harvest, pending clinical studies. It may have wide applications as a vascularized nerve graft, including being ideal as a vascularized cross-facial nerve graft because its nerve diameter is similar to the distal facial nerve branches. The accompanying artery is a good anastomotic match to the superior labial artery.

The Bahariyeh iron oxide copper–gold deposit, Khaf-Khashmar-Bardaskan magmatic belt, NE Iran: Constraints from geochemical, fluid inclusions, and O-S isotope studies

The Bahariyeh deposit is located in the central segment of the Khaf-Kashmar-Bardaskan magmatic belt (KKBMB), northeast Iran. Previous U-Pb data on zircon revealed an age of 38–41 Ma for the felsic-intermediate intrusions. The stockwork like vein orebodies are hosted in Eocene monzodiorite porphyry rocks which have strong structural controls imposed by the Great Dorouneh Fault System. Hydrothermal alteration is dominated by silicification, propylitic (chloritization), argillic, and sericitic zones. The mineralized veins in the Bahariyeh deposit can be divided into seven types: 1) quartz ± pyrite; 2) quartz + specular hematite + pyrite ± gold; 3) quartz + chalcopyrite + pyrite; 4) quartz + specular hematite + chalcopyrite + pyrite ± sphalerite ± galena ± gold; 5) chalcopyrite + specular hematite + pyrite ± gold; 6) specular hematite ± pyrite; and 7) chalcopyrite + pyrite. The various vein-style orebodies contain high concentrations of Cu, Au, Pb, Zn, and Ag. Microthermometric measurements of fluid inclusions in mineralized veins demonstrate homogenization temperatures in the range of 271–500 °C (mode of 300 °C), and corresponding salinities in the range of 7.9–26.3 wt% NaCl equivalent. The δ18OWater values calculated from δ18O of quartz, and the δ34S values of chalcopyrite reveal a dominantly magmatic origin for the ore-forming fluids. The fluid inclusions indicate that mixing between magmatic fluids and meteoric water, together with cooling, are the dominant mechanisms for metal deposition in the Bahariyeh district. The combination of ore deposit geology, alteration type, fluid evolution processes, and O–S isotope data suggest that the Bahariyeh deposit be classified as a Cu ± Au-rich iron oxide-copper–gold (IOCG) system.

Upper maastrichtian palynology and paleoenvironment of the Urucutuca Formation, Almada basin (BA), Brazil

Hydrocarbon exploration involving the Urucutuca Formation is taking place in several basins located mainly in the central segment of the eastern Brazilian margin, including the Almada Basin. Relatively rich accumulations of organic material and promising prospects, especially for gas, have been discovered. The Brazilian National Petroleum Agency (ANP) considers the Urucutuca Formation as a speculative play exploratory (Urucutuca-Urucutuca) in deep and ultra-deep areas of the Almada Basin, including others.The focus was on improving the understanding of the sediments of the Urucutuca Formation and establishing a palynostratigraphic outline for the upper cretaceous strata, which still need to be updated. Therefore, integrated palynological, palynofaciological, and organic-geochemical (total organic carbon -TOC) investigation methods were carried out. For this purpose, 250 m of well 1-SST-01, drilled in the onshore part of the Almada Basin in Bahia State, were analyzed using 26 core samples along the Urucutuca Formation.By typifying palynofaciological variations based on organic matter content in conjunction with palynological and geochemical data, it was possible to distinguish three palynofacies with different characteristics of the marine influence environment. Palynofacies 1, the amorphous organic matter (AOM) group, predominates with proportions up to 54.1 and a TOC of 0.75%. The high phytoclasts percentage (70%) and a TOC content of 1% characterize the Palynofacies 2. Palynofacies 3, on the other hand, has the highest content of marine palynomorphs (40%).The analysis of total organic carbon yielded values ranging from 0.04% to 1.85%, which were heterogeneously distributed throughout the borehole.The palynological succession showed a dominance of representatives of continental origin. However, marine elements (dinoflagellates and microforaminiferal inner tests) are present throughout the section.Two expressive occurrences of dinoflagellate cysts are evident throughout the section. In the basal and middle portions, quantity and diversity suggest transgressive events or at least sea-level fluctuations. Biostratigraphically, the unit could be placed in the Tricornites elongatus (P-470) Biozone of the Crassitricolporites brasiliensis (P-450) Superzone and assigned to the Eomaastrichtian. These biostratigraphic units are consistent with the proposed zonation for other basins of the Brazilian Atlantic margin.Palynofacies and palynological data allowed the observation of variations in a predominantly platform paleoenvironment, sometimes distal and sometimes more proximal, with possible transgressions.

Drainage network rearrangement during the formation and segmentation of a Paleogene intraplate half-graben: Insights from fluvial captures records and longitudinal profiles

Rivers play an important role in modifying landscapes through denudation processes, which can be influenced by changes in tectonics, climate and eustasy, causing erosive pulses and river capture events that alter the geometry and topology of the drainage network. Therefore, drainage networks are not static features over time and are modified and rearranged by shifts in their boundary conditions until a state of dynamic equilibrium is reached in the landscape. The region of the Paraíba do Sul Middle Valley (PSMV), in Southeastern Brazil, has important records of captures and recent drainage rearrangements, which show a state of transition in the landscape and, consequently, the reorganization of drainage networks. This region is in the central segment of the Continental Rift of Southeastern Brazil (CRSB), a prominent tectonic feature that can be described as an intraplate half-graben. While fluvial profiles and fluvial gradient indices are valuable tools for studying the landscape evolution, their application to investigate the erosive power of rivers and how the topography of a half-graben affects the rearrangement of the drainage network over geological time is still limited. Specifically, there is a need to explore how the topography of the active border of a half-graben differs from that of the flexural border in terms of river network organization and fluvial erosion patterns. This study aims to characterize the different stages of rearrangements of the drainage network and their relation with the events of formation and segmentation of a half-graben. A total of 21 basins were analyzed in both Fault and Flexural Border sectors, extracting geomorphic parameters, such as slope, drainage area, concavity, χ and ksn. A more specific study was carried out in areas where river captures were recognized as been related to the half-graben formation and segmentation events. The ksn calculated for the main rivers demonstrates that the formation of the rift and its consequent configuration in half-graben granted a greater erosive power for the basins that drained the active fault of the rift, represented by the basins of the Fault Border Sector of the study area. The tectonic events registers in the fluvial system were analyzed using the χ method and the main migration tendency of the dividers was extracted from the difference in the values of this parameter in areas close to the interfluves. With this, it becomes evident that the geometric configuration imposed in the half-graben establishes, from the beginning of the rift phase, an important control on the erosion potential of the rivers located in the active and flexural borders. This control resulted in ancient river captures, currently exposed as inflections in the main river channels towards the local depocenters, thus demonstrating that this type of tectonic event can generate disturbances in the river system that can be observed even today, tens of millions of years after it happened.