Distribution Of Scatterers Research Articles

Investigation of Zn alloy coating with submicron phases on magnesium alloy by the novel hot-dip process

A Zn alloy coating with submicron phases was fabricated on magnesium alloys by a novel hot-dip process, exhibiting excellent corrosion resistance. The microstructure and phases of coatings were characterized and their correlation with the corrosion performance was investigated. The results indicated that the coating immersed in Zn-3Mg molten bath for 4 s primarily consisted of submicron dot-like Zn phases with well-ordered distribution, while the coating immersed in Zn-3Mg molten bath for 7 s mainly comprised rod-like compact MgZn2 phases with a scattered distribution of Zn phase. The presence of these fine phases of coatings effectively impeded ion permeation in corrosive environments, leading to a significant enhancement in corrosion resistance. Notably, the exceptional corrosion resistance of the coating immersed for 4 s can be attributed to the submicron Zn phase with a grain size of 0.51 μm, resulting in a 62-fold increase in low-frequency impedance value compared to the AZ31 alloy, and a 22-fold decrease in corrosion rate compared to the AZ31 alloy.

The Morphological Diversity of Dragon Lacewing Larvae (Nevrorthidae, Neuroptera) Changed More over Geological Time Scales Than Anticipated.

Nevrorthidae, the group of dragon lacewings, has often been considered a relic group. Today, dragon lacewings show a scattered distribution, with some species occurring in southern Europe, Japan, Australia, and one in China. The idea that this distribution is only a remnant of an originally larger distribution is further supported by fossils of the group preserved in ambers from the Baltic region (Eocene, ca. 35-40 MaBP) and Myanmar (Kachin amber, Cretaceous, ca. 100 MaBP). Larvae of the group are slender and elongated and live mostly in water. Yet, larvae are in fact very rare. So far, only slightly more than 30 larval specimens, counting all extant and fossil larvae, have been depicted in the literature. Here, we report numerous additional specimens, including extant larvae, but also fossil ones from Baltic and Kachin amber. Together with the already known ones, this sums up to over 100 specimens. We analysed quantitative aspects of the morphology of these larvae and compared them over time to identify changes in the diversity. Despite the enriched sample size, the data set is still unbalanced, with, for example, newly hatched larvae (several dozen specimens) only known from the Eocene. We expected little change in larval morphology over geological time, as indicated by earlier studies. However, on the contrary, we recognised morphologies present in fossils that are now extinct. This result is similar to those for other groups of lacewings which have a relic distribution today, as these have also suffered a loss in diversity in larval forms.

A Reinforcement Learning Method for Rearranging Scattered Irregular Objects Inside a Crate

Arranging objects from a random and scattered distribution into an integral part has many applications, including bin packing, logistics, and other industrial fields. Measurement noises, manipulation uncertainties, models of irregular objects, and rich contacts bring considerable challenges to the improvements of the overall performance, such as seamlessness of the final pattern and task efficiency. In this paper, we propose an end-to-end reinforcement learning strategy that generates a series of pushing movements for scattered irregular objects inside a crate. An abstracted and sparse reward function is proposed to evaluate the pushing performance, and Proximal Policy Optimization (PPO) learning method that simultaneously trains a Convolutional Neural Network (CNN) and a fully connected actor network is developed for end-to-end decision making. The proposed method is evaluated in both simulation and real-world scenarios. The results show that the proposed method can arrange the scattered objects tightly to fit into each other in an efficient and flexible way, and can be transferred to the real world with unseen objects.

Population genetic characterization of (Aedes albopictus) mosquitoes (Diptera: Culicidae) from the Yangtze River Basin of China based on rDNA-ITS2.

Aedes albopictus is an important vector of many mosquito-borne viral diseases, including dengue fever and Zika. In recent years, it has spread and colonized tropical, subtropical and temperate regions worldwide. Monitoring of Ae. albopictus population dynamics is an important tool for early warning of mosquito-borne infections. Because the genetic diversity and genetic structure of natural populations are the genetic bases of population dynamics, studies of population genetics can reveal the origin, differentiation and dispersal characteristics of Ae. albopictus populations. Then, their evolutionary potential and environmental adaptability can be analyzed, providing a theoretical basis for the formulation of accurate Ae. albopictus surveillance and integrated control programs. In 2018, 552 Ae. albopictus larvae were collected during an invasive mosquito species surveillance project in China's Yangtze River Basin. Morphological analysis was performed to assign the adult mosquitoes to species, and then the genetic marker ITS2 was amplified and sequenced. There were 179 haplotypes among 552 ITS2 sequences. In total, 155/179 (86.59%) haplotypes were specific to individual populations, and 24/179 (13.41%) haplotypes were shared by populations. Hap4 (126), Hap7 (43), and Hap16 (34) were the most numerous haplotypes and the most widely distributed. The overall Hd was 0.928, π was 0.031, the mean nucleotide difference number (K) was 7.255, and the number of segregating sites was 169. TCS network maps mainly showed a single star-like scattered distribution. According to geographical location, there were no obvious haplotype groups, and the haplotypes were intricately connected. The genetic diversity of Ae. albopictus populations in the Yangtze River Basin was high. The molecular variance observed in the populations of Ae. albopictus mainly occurred among individuals within populations, accounting for 98.79% of the total, while that among populations accounted for only 1.21% of the total. Only the populations of Ae. albopictus in the Chongqing and Sichuan regions showed a moderate degree of population genetic differentiation, while genetic differentiation between the other regions were small, gene exchange was very common, and genetic differentiation within populations was minimal. According to this study, the genetic diversity of Ae. albopictus populations in the Yangtze River Basin is high, the genetic differentiation among populations is small, and gene exchange is common. In addition, frequent interregional exchange exacerbates the abnormal spread of vectors. This study highlighted the potential spread route of the vector Ae. albopictus in the Yangtze River Basin. There are three potential dispersal routes for Ae. albopictus populations in the Yangtze River Basin. The findings could be helpful for effective surveillance and early warning of Ae. albopictus vectors.

Study on the Spatiotemporal Evolution of the “Contraction–Expansion” Change of the Boundary Area between Two Green Belts in Beijing Based on a Multi-Index System

In serving as a pivotal strategy for curbing urban sprawl, large-scale urban green belts, being a significant constituent of the urban green space, have been ubiquitously employed in the scheming and fabrication of green space systems in global megacities. Nevertheless, the disregard for research into the independent alteration mechanism of urban green space, coupled with the reactive approach of planning and construction and the singularity of quantitative indices, has engendered challenges in the creation of urban green belts. This paper presents an investigation into the juncture zone of two green belts in Beijing as a case study, erecting a “contraction–expansion” flux model of its green space and gauging the transformational traits of the green space in light of its spatial–temporal evolution with regards to its quantity, space, and connectivity among others. Findings reveal that between 2005 and 2012, the green space in Beijing underwent an approximately 20% alteration, with the green belt intersection zone’s green space area experiencing a dual trajectory shift of “expansion-contraction”. This shift was primarily characterized by expansion before 2015 and contraction from 2015 onwards. Concerning spatial attributes, patterns of expansion and aggregation were discernible in scattered distribution, whereas contraction and aggregation were evident in mass and spaced distribution. Spatial stability was influenced by the change model, marked by a shift in the center of gravity from a “north-south-east” orientation to a “northwest-southeast” direction. At the connectivity stratum, noticeable variations were witnessed in both the overall and local connectivity levels pre- and post-2015. Regarding individual connectivity, three vital nodes of stable linear connectivity were identified, playing a decisive role in defining the dispersion of crucial corridors within the area of study.

Landscape Dynamics and Ecological Risk Assessment of Cold Temperate Forest Moose Habitat in the Great Khingan Mountains, China.

The change in habitat pattern is one of the key factors affecting the survival of the moose population. The study of the habitat landscape pattern is the key to protecting the Chinese cold-temperate forest moose population and monitoring the global distribution of moose. Through the ecological risk assessment of the moose habitat landscape pattern in a cold-temperate forest, we hope to assess the strength of habitat resistance under stress factors. This study provides a theoretical basis for the protection of the moose population in the cold-temperate forest in China and the establishment of the cold-temperate forest national park. In the study, the MaxEnt model, landscape index calculation and ecological risk assessment model construction were used to analyze the field survey and infrared camera monitoring data from April 2014 to January 2023. The habitat suitability layer of the moose population in the Nanwenghe National Nature Reserve of the Great Khingan Mountains was calculated, and the range of the moose habitat was divided based on the logical threshold of the model. The landscape pattern index of the moose habitat was calculated by Fragstats software and a landscape ecological risk assessment model was established to analyze the landscape pattern and ecological risk dynamic changes of the moose habitat in 2015 and 2020. The results showed that under the premise of global warming, the habitat landscape contagion index decreased by 4.53 and the split index increased by 4.86 from 2015 to 2020. In terms of ecological risk: the area of low ecological risk areas increased by 0.88%; the area of medium ecological risk areas decreased by 1.11%; and the area of high ecological risk areas increased by 0.23%. The fragmentation risk of the landscape pattern of the moose habitat tends to increase, the preferred patch type is dispersed, the degree of aggregation is low, and the risk of patch type transformation increases. The middle and high ecological risk areas are mainly concentrated in the river area and its nearby forests, showing a fine and scattered distribution. Under the interference of global warming and human activities, the fragmentation trend of the moose habitat in the study area is increasing, and the habitat quality is declining, which is likely to cause moose population migration. For this reason, the author believes that the whole cold temperate forest is likely to face the risk of increasing the transformation trend of dominant patch types in the cold-temperate coniferous forest region mainly caused by global warming, resulting in an increase in the risk of habitat fragmentation. While the distribution range of moose is reduced, it has a significant impact on the diversity and ecological integrity of the whole cold-temperate forest ecosystem. This study provides theoretical references for further research on the impact of climate warming on global species distribution and related studies. It is also helpful for humans to strengthen their protection awareness of forest and river areas and formulate reasonable protection and sustainable development planning of cold-temperate forests. Finally, it provides theoretical references for effective monitoring and protection of cold-temperate forests and moose population dynamics.

Corrosion and cavitation erosion behaviors of laser clad FeNiCoCr high-entropy alloy coatings with different types of TiC reinforcement

By using laser cladding (LC), high entropy alloy coatings (HEACs) with FeNiCoCr as the base material and TiC added directly (D-TiC) and in-situ (I-TiC) were created. The phase composition, microstructure, mechanical characteristics, electrochemical corrosion, and cavitation erosion behavior of HEACs were examined in relation to two TiC addition methods, and a thorough investigation of the effects of mechanical characteristics and corrosion resistance on cavitation erosion behavior was conducted. Large clusters of TiC were visible in the D-TiC HEAC, in contrast to the sparse and scattered distribution of them in the I-TiC HEAC. The average grain size of the composite coating substantially fell from 25.7 μm for FeNiCoCr coating to 11.8 μm for D-TiC coating and 9.4 μm for I-TiC coating when TiC were included in the skeleton. The I-TiC composite coating precipitated by nucleation and growth with the maximum average microhardness of 440 ± 6 HV under the combined action of solid solution strengthening, fine crystal strengthening, and second phase strengthening. In 3.5 wt% NaCl solution, the galvanic corrosion between TiC particles and the FCC matrix significantly weakened the corrosion resistance of the D-TiC HEAC, with the Icorr reaching 3.47 × 10−2 ± 0.8 μA/cm2. The I-TiC HEAC exhibited approximately equal corrosion resistance to FeNiCoCr with an Icorr of merely 5.92 × 10−3 ± 0.3 μA/cm2. Varying cavitation incubation periods (IPs) existed in 316 SS and HEACs at the beginning of the cavitation experiment. The mean depth of erosion rate (MDER) of FeNiCoCr, D-TiC and I-TiC coatings was 0.19 ± 0.09, 0.42 ± 0.04, and 0.15 ± 0.02 μm h−1, respectively, which was only 1/5, 1/2, and 1/6 of that of substrate (0.90 ± 0.13 μm h−1). The cavitation surface of 316 SS was full of craters and cracks without any original surface. Meanwhile, due to the weak interfacial bonding strength between TiC/HEA, the cavitation erosion morphologies of D-TiC HEAC contained spallation of large TiC particles. Attributed to its ideal mechanical and corrosion resistance, the I-TiC composite coating demonstrated the best resistance to cavitation erosion.

Mathematical Model for Deformation Analysis of Guta

In this paper, the data in the appendix were removed from the missing data and the valid data were retained. The following problems were solved by the statistical processing of the valid data. While examining on foot the measured data of tower layers' positions in different years and different classifications, the measured coordinates of each layer of the ancient tower in 1986 will be taken as the basis, and the scatter distribution of each layer of the tower will be made by MATLAB, and the coordinate point positions are found to be on the same basic circular plane. Based on the minimum sum of distances from any point on the same circular plane to the fixed points (a, b, c), a nonlinear programming model is established, and by substituting the data to calculate the The coordinates of the center of each level of the ancient pagoda four years ago were calculated by substituting the data. When analyzing the settlement of the gutta, the change of the horizontal plane is not considered, but the change of the vertical ground coordinates of the gutta, i.e. the change of the Z-axis causes the overall rise and fall of the gutta. Based on the center coordinates of each level of the guttae obtained from problem 1, the three settlement differences, average settlement and annual average settlement from 1986 to 1996,1996 to 2009, and 2009 to 2011 are calculated. It can be seen that the ancient tower is sinking year by year, and the sinking rate increases year by year.

Monitoring Ground Displacement in Mining Areas with Time-Series Interferometric Synthetic Aperture Radar by Integrating Persistent Scatterer/Slowly Decoherent Filtering Phase/Distributed Scatterer Approaches Based on Signal-to-Noise Ratio

During the interferometric synthetic aperture radar (InSAR)-based ground displacement monitoring in mining areas, the overlying land is mainly covered by low vegetation and arable land, which makes interferograms acquired by InSAR techniques easily susceptible to decorrelation, resulting in the quantity and density of highly coherent points (CPs) are not enough to reflect the spatial location and spatio-temporal evolution process of ground displacement, which is hardly meeting requirements of high-precision ground displacement monitoring. In this study, we developed an approach for monitoring ground displacement in mining areas by integrating Persistent Scatterer (PS), Slowly Decoherent Filtering Phase (SDF), and Distributed Scatterer (DS) based on signal-to-noise ratio (SNR) to increase the spatial density of CPs. A case study based on a mining area in Heze was carried out to verify the reliability and feasibility of the proposed method in practical applications. Results showed that there were four significant displacement areas in the study area and the quantity of CPs acquired by the proposed method was maximum 6.7 times that of conventional PS-InSAR technique and maximum 2.3 times that of SBAS-InSAR technique. The density of CPs acquired by the proposed method increased significantly. The acquired ground displacement information of the study area was presented in more detail. Moreover, the monitoring results were highly consistent with ground displacement results extracted by PS-InSAR and SBAS-InSAR methods in terms of displacement trends and magnitudes.

Research on a measurement method for spatio-temporal distribution of fragments based on a high-speed camera network

To reliably measure multiple spatio-temporal distribution parameters of fragments in the blast field, a measurement method for spatio-temporal distribution of fragments based on a high-speed camera network is proposed. The method is based on the principle of binocular stereo vision measurement and consists of four steps: fragment image acquisition, target detection of multi-view images, fitting of motion trajectory, and calculation of the spatio-temporal distribution parameters. The test results demonstrate that the method can simultaneously measure multiple parameters in the intersecting field of view. Compared with the measurement results of the array target, the absolute value of the measurement relative error of velocity was less than 1.5%, and the measurement results of scatter angle and distribution density were consistent. It indicates that the measurement results of the proposed method are reliable, and the method is a feasible and effective measurement method for spatio-temporal distribution parameters of fragments in the explosion filed.

Radiance and fluence in a scattering disc under Lambertian illumination

We investigated light propagation in a (non-)scattering disc under uniform Lambertian illumination analytically and by means of a Monte Carlo simulation. Thereby, we found that in a non-scattering disc the fluence plateaus near the center, and, starting at a critical radius determined by the refractive index, decays towards the boundary. A non-vanishing very small scattering coefficient causes an abrupt transition to a homogeneous fluence, similarly to the case of a sphere. Moreover, absorption and inhomogeneous scatterer distributions were considered, with the absorption leading to a reduced fluence near the disc center. In contrast to the homogeneously scattering case, it is shown that a non-vanishing scattering coefficient inside the critical radius does not cause a homogeneous fluence. New analytic solutions of the radiative transfer equation for radiance and fluence of unscattered and singly scattered light showed excellent agreement with their counterparts obtained via Monte Carlo simulation within its statistical noise. Additionally, we derived an analytic expression for the unscattered radiance and fluence in case of Lambertian illumination at a single point on the disc boundary, which also describes caustics.

Relationship between Lidar-Derived Canopy Densities and the Scattering Phase Center of High-Resolution TanDEM-X Data

The estimation of forestry parameters is essential to understanding the three-dimensional structure of forests. In this respect, the potential of X-band synthetic aperture radar (SAR) has been recognized for years. Many studies have been conducted on deriving tree heights with SAR data, but few have paid attention to the effects of the canopy structure. Canopy density plays an important role since it provides information about the vertical distribution of dominant scatterers in the forest. In this study, the position of the scattering phase center (SPC) of interferometric X-band SAR data is investigated with regard to the densest vegetation layer in a deciduous and coniferous forest in Germany by applying a canopy density index from high-resolution airborne laser scanning data. Two different methods defining the densest layer are introduced and compared with the position of the TanDEM-X SPC. The results indicate that the position of the SPC often coincides with the densest layer, with mean differences ranging from −1.6 m to +0.7 m in the deciduous forest and +1.9 m in the coniferous forest. Regarding relative tree heights, the SAR signal on average penetrates up to 15% (3.4 m) of the average tree height in the coniferous forest. In the deciduous forest, the difference increases to 18% (6.2 m) during summer and 24% (8.2 m) during winter. These findings highlight the importance of considering not only tree height but also canopy density when delineating SAR-based forest heights. The vertical structure of the canopy influences the position of the SPC, and incorporating canopy density can improve the accuracy of SAR-derived forest height estimations.

Fabrication of tungsten-based optical diffuser using fiberform nanostructure via efficient plasma route.

Optical diffusion is an essential process used to manage photons in a wide range of photoelectric systems. This work proposes an approach to fabricate novel optical diffusers by a plasma-processing technique, using fiberform nanostructures formed by helium plasma irradiation and subsequent annealing. After an annealing procedure in the air for oxidation, the optical properties and the light-diffusing abilities of these nanostructured thin films were studied. In addition to the morphology analysis and total transmittance measurement, the diffusion efficiency of the optical diffusers was analyzed using a transmitted scatter distribution function (TDF). It was revealed that the diffusion efficiency of a device with an irradiation time of 30 minutes could reach 97%. The results demonstrate the potential of these nanostructured optical diffusers for various photoelectric applications.

Parallel EM optimization using improved pole‐residue‐based neuro‐TF surrogate and isomorphic orthogonal DOE sampling for microwave components design

AbstractDirect electromagnetic (EM) optimization for microwave components design is usually a time‐consuming process. To improve the optimization efficiency, this paper proposes a novel parallel EM optimization technique exploiting improved pole‐residue‐based neuro‐transfer function (neuro‐TF) surrogate and isomorphic orthogonal design of experiment (DOE) sampling strategy. We propose a new sampling method combining isomorphic orthogonal DOE and parallel EM simulations to generate training data for developing the neuro‐TF surrogate. This proposed sampling method can ensure the scattered distribution of data samples in the overall optimization process, thus effectively improving the surrogate accuracy and increasing the optimization speed. We also propose a new pole‐residue tracking technique for order‐changing to solve the discontinuity problem of pole/residues during the neuro‐TF surrogate development. Different from the fixed split ratio in existing pole‐residue tracking technique, the split ratio of poles and residues in the proposed technique is adaptive and determined according to the information of neighboring samples. Therefore, the continuity and smoothness of pole/residues after the splitting are improved, so as the neuro‐TF surrogate accuracy. In addition, the trust region algorithm is exploited during EM optimization to improve the convergence speed. In this way, the proposed EM optimization technique obtains the optimal solution in a shorter time with fewer iterations than the existing techniques. Two examples of EM optimizations of microwave components are used to illustrate the proposed technique.

The Lorentz Gas with a Nearly Periodic Distribution of Scatterers

We consider the Lorentz gas in a distribution of scatterers which microscopically converges to a periodic distribution, and prove that the Lorentz gas in the low density limit satisfies a linear Boltzmann equation. This is in contrast with the periodic Lorentz gas, which does not satisfy the Boltzmann equation in the limit.

Stream power curve–loop–spiral conceptual method and an application to rivers of Taiwan

Study regionEighteen main rivers in Taiwan. Study focusThe concept of total stream power (TSP) or specific stream power (SSP) has been investigated previously as an index for assessing the status of a river channel. Here, we introduce a new diagram called the “stream power loop” to review variations in fluvial conditions, morphology, and sediment transport potential from river source to estuary. Because of its physical basis, the loop diagram reflects fluvial morphology and watershed conditions. Additionally, we present a spiral diagram that depicts variations in the spatial gradients of TSP and SSP. The gradient implied the sediment transport trend, which from upstream to downstream changes gradually from scouring to siltation in ideal conditions. The loop and spiral diagrams provide an overview of the fluvial system. New hydrological insights for the regionThe loop diagram applications in Taiwan categorized the rivers into three types: simple loop, maple-leaf loop, and complex loop. Diverse geology increases the likelihood of large tributaries and abrupt changes in terrain, both of which affect the components of stream power–discharge and slope. The scatter distribution of all the data aggregated from the 18 rivers showed a shrinking radius and a counter-clockwise spiral pathway, passing through the mountain river zone, the braided river zone, and finally to the straight & meandering river zone. The result supported the concept of stream power loop and indicated that stream power loop can interpret the status of the river systems.

Cytoarchitectureal changes in hippocampal subregions of the NZB/W F1 mouse model of lupus

Over 50% of clinical patients affected by the systemic lupus erythematosus disease display impaired neurological cognitive functions and psychiatric disorders, a form called neuropsychiatric systemic lupus erythematosus. Hippocampus is one of the brain structures most sensitive to the cognitive deficits and psychiatric disorders related to neuropsychiatric lupus. The purpose of this study was to compare, layer by layer, neuron morphology in lupus mice model NZB/W F1 versus Wild Type mice.By a morphometric of cells identified on Nissl-stained sections, we evaluated structural alterations between NZB/W F1 and Wild Type mice in seven hippocampal subregions: Molecular dentate gyrus, Granular dentate gyrus, Polymorph dentate gyrus, Oriens layer, Pyramidal layer, Radiatum layer and Lacunosum molecular layer. By principal component analysis we distinguished healthy Wild Type from NZB/W F1 mice. In NZB/W F1 mice hippocampal cytoarchitecture, the neuronal cells resulted larger in size and more regular than those of Wild Type. In NZB/W F1, neurons were usually denser than in WT. The Pyramidal layer neurons were much denser in Wild Type than in NZB/W F1. Application of principal component analysis, allowed to distinguish NZB/W F1 lupus mice from healthy, showing as NZBW subjects presented a scattered distribution and intrasubject variability.Our results show a hypertrophy of the NZB/W F1 hippocampal neurons associated with an increase in perikaryal size within the CA1, CA2, CA3 region and the DG. These results help advance our understanding on hippocampal organization and structure in the NZB/W F1 lupus model, suggesting the hypothesis that the different subregions could be differentially affected in neuropsychiatric systemic lupus erythematosus disease. Leveraging an in-depth analysis of the morphology of neural cells in the hippocampal subregions and applying dimensionality reduction using PCA, we propose an efficient methodology to distinguish pathological NZBW mice from WT mice.”

Implementation of Ecological Distribution of Venomous Snakes for Clinical Management of Snakebite in Bangladesh

Background: Snakebite envenoming is a global health problem, mostly in tropical and subtropical countries. Bangladesh is a subtropical country facing thousands of snakebite envenoming death every year. Knowledge of the distribution of venomous snakes is necessary to identify snakebite-prone areas, develop strategies for prevention and management, and reduce venom-induced mortalities and morbidities. Methods: An integrated effort of direct observations of snakes, qualitative analysis of museum specimen records, clinical records of snakebites, and scholarly literature records were used to understand the pattern of distribution of venomous snakes in Bangladesh. Results: We enlist 65 venomous snake species from Bangladesh and present detailed documentation on their distribution pattern. However, only nine species were considered medically relevant species because of their venom potentiality to kill humans and available clinical records of envenomation. The distribution pattern of those species divides the country into two major portions. A portion consists of northern, northwestern, and western parts of the country, which are habitats of Naja naja, Bungarus caeruleus, and B. lividus. Another portion comprised of the northeastern, southeastern, and southern parts of the country provides habitats for N. kaouthia, B. niger, and Trimeresurus erythrurus. However, Daboia. russelii had a different distribution pattern along the bank of the Padma and Meghna, and some coastal districts. Moreover, B. walli had a scattered distribution over the country. The knowledge of this ecological distribution of venomous snakes across the country bears a significant practical effect on clinical management of snakebite. Treating physicians can have a better understanding of possible offending snake species using this knowledge and the clinical syndromes produced by venoms. Conclusion: Pattern of distribution of medically relevant venomous snakes in Bangladesh approaches to initiate concise and specific bite management strategies for two distinct distributional regions of the country. Moreover, the distribution of D. russelii and B. walli demands specific strategies for bite management. J MEDICINE 2023; 24(2): 139-151

A review of the current state of knowledge on Pseudoxytenanthera ritchiei- a lesser known bamboo species with high utilization potential from Peninsular India

Pseudoxytenanthera ritchiei (Munro) H. B. Naithani is a unique bamboo species with fully solid culms. This bamboo species is endemic to the Peninsular India and has a scattered distribution in the forest ecosystems of Kerala. In Kerala, the species was abundantly found in Nilambur and Mannarkad forests and had high demand in the market. However, unsustainable harvesting over a significant period resulted in resource depletion from these forests (Kumar et al., 2009). Though P. ritchiei shares many characteristics which make Pseudoxytenanthera stocksii a commercially important bamboo species, the former is not listed as a priority species by the National Bamboo Mission while the latter is included in the list. Moreover, the potential of P. ritchiei remains untapped in Kerala, primarily due to a lack of information on its distribution and availability, and secondly due to a lack of supply of sufficient quantity for commercial use. These are clumping bamboo and do not require much space, making them suitable for home gardens and as a border crop in fields. Hence, we argue that there is a good justification for this species to be given preference and large-scale cultivation to be encouraged outside forest areas after having developed appropriate methods for quality stock production. Steps must also be taken to ensure the conservation of the species in its natural habitat to prevent the loss of the wild and diverse genotypes which at present lack sufficient documentation. This review features information gleaned from available literature on this less-studied species, and its potential for utilization. The currently available information relating to distribution, propagation, floral morphology, flowering history, eco-system services etc. is also highlighted.

Fenestrated screws in osteoporotic spine—Is there an association between the cement distribution and DEXA scan T score?

Abstract Purpose: Cement distribution in spinal stabilization with fenestrated screws is unpredictable in patients with osteoporosis. The objective of our study was an assessment of cement distribution while using fenestrated screws and to establish an association between cement distribution and the Dual Emission X-ray Absorptiometry (DEXA) scan T scores. Materials and Methods: Osteoporotic patients who underwent spinal stabilization with fenestrated screws by a single surgeon with a minimum follow-up of one year were included. Cement distribution (four zones comprising the vertebral body and the pedicle), a pattern of distribution (concentrated or scattered) and cement leakage were assessed on CT scans. Patients were categorized into two groups based on their DEXA scan T scores to test an association between the pattern of distribution of cement and the scores. Clinical improvement was determined using visual analogue scale and Oswestry disability index scores. Results: A total of 126 screws were analyzed in 20 patients with a mean age of 69 years and a mean follow-up of 18 months. Out of 126 screws, 114 (90.47%) had cement in Zones 1 and 2. In total, 58 screws had a concentrated pattern of distribution of cement, whereas 68 screws had a scattered distribution, and the odds ratio of a scattered pattern of distribution was 6.31:1 if the DEXA scan T score was “below (−)3.0.” Clinical improvement was calculated in percentage of change from the preoperative value (mean % visual analogue scale change = 65.13 ± 7.59 and mean % Oswestry disability index change = 43.14 ± 7.24). Conclusion: The pattern of cement distribution in fenestrated screws relates well with the DEXA scan T scores and their usage should be strongly considered in patients with poorer scores. However, there is no relevant difference between the pattern of distribution and the clinical outcome.