Minimum Density Research Articles

Accelerating thermokarst lake changes on the Qinghai–Tibetan Plateau

As significant evidence of ice-rich permafrost degradation due to climate warming, thermokarst lake was developing and undergoing substantial changes. Thermokarst lake was an essential ecosystem component, which significantly impacted the global carbon cycle, hydrology process and the stability of the Qinghai–Tibet Engineering Corridor. In this paper, based on Sentinel-2 (2021) and Landsat (1988–2020) images, thermokarst lakes within a 5000 m range along both sides of Qinghai–Tibet Highway were extracted to analyse the spatio-temporal variations. The results showed that the number and area of thermokarst lake in 2021 were 3965 and 4038.6 ha (1 ha = 10,000 m2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{2}$$\\end{document}), with an average size of 1.0186 ha. Small thermokarst lakes (<\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$<\\,$$\\end{document}1 ha) accounted for 85.65% of the entire lake count, and large thermokarst lakes (>\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$>\\,$$\\end{document}10 ha) occupied for 44.92% of the whole lake area. In all sub-regions, the number of small lake far exceeds 75% of the total lake number in each sub-region. R1 sub-region (around Wudaoliang region) had the maximum number density of thermokarst lakes with 0.0071, and R6 sub-region (around Anduo region) had the minimum number density with 0.0032. Thermokarst lakes were mainly distributed within elevation range of 4300 m–5000 m a.s.l. (94.27% and 97.13% of the total number and size), on flat terrain with slopes less than 3∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ$$\\end{document} (99.17% and 98.47% of the total number and surface) and in the north, south, and southeast aspects (51.98% and 50.00% of the total number and area). Thermokarst lakes were significantly developed in warm permafrost region with mean annual ground temperature (MAGT) > − 1.5 ∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ$$\\end{document}C, accounting for 47.39% and 54.38% of the total count and coverage, respectively. From 1988 to 2020, in spite of shrinkage or even drain of small portion of thermokarst lake, there was a general expansion trend of thermokarst lake with increase in number of 195 (8.58%) and area of 1160.19 ha (41.36%), which decreased during 1988–1995 (− 702 each year and − 706.27 ha/yr) and then increased during 1995–2020 (184.96–702 each year and 360.82 ha/yr). This significant expansion was attributed to ground ice melting as rising air temperature at a rate of 0.03–0.04 ∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ$$\\end{document}C/yr. Followed by the increasing precipitation (1.76–3.07 mm/yr) that accelerated the injection of water into lake.

Ventilation characteristics of double-forced air pipe ventilation in comprehensive mechanized excavation face and determination of its optimal parameters

ABSTRACT This study proposes a ventilation and dust control approach using double-forced air pipes at the tunnel excavation face, aiming to optimize the dust control and reduction measures for underground coal mining environment. We designed a physical model in proportion to the 11,139 excavation face in the Zhangji Coal Mine of China Huaihe Energy Holding Group Coal Company. To begin with, CFD numerical simulation was employed to unveil the basic laws of the double-forced air pipe ventilation approach, including airflow characteristics and dust concentrations. The orthogonal experimental method was then adopted to analyze the influence mechanism of installation location and airflow ratio of the double pipes on the dust density around the driver’s operating space. Results suggest that the double-forced air pipe ventilation can efficiently improve the airflow velocity at the excavation face, reaching 5.54 m/s. With the minimum dust density around the driver’s operating space as the optimal parameter standard and combined with the R value, the three factors in the orthogonal experiment can be sorted as: the distance between the forced ventilation pipe at the driver’s side and the excavation face (R = 206.91) > the distance between the forced ventilation pipe at the return air side and the excavation face (R = 171.72) > the airflow ratio of the two pipes (R = 77.52). The optimal combination is that the distance between the ventilation pipe at the driver’s side and the excavation face is 5 m, the distance between the ventilation pipe at the return air side and the excavation face is 5 m, and the airflow ratio of the two pipes is 6:4. In such a case, the dust density around the driver’s operating space is 48.21 mg/m3, achieving an ideal dust control effect.

Investigations on performance parameters of graphene interfacial layer modified FASnI3: Zn-based lead-free perovskite solar cells

The emerging and extensively approved solar technology be certainly of perovskites, by virtue of their exceptional contributions. However, their massive production senses on the remaining hurdles that are to be crossed before making them commercially diligent. This investigation highlights the measures to be taken to implement a lead free, highly stable perovskite solar cells (PSCs). The use of Zn-doped, Sn-based as perovskite (PVT) absorber layer together with graphene passivation layer at PVT/ hole transport layer (HTL) interface resulted in effective implementation of this phenomenon. In this research, a systematic numerical validation of PSC structure with FTO/ZnOS/FASnI3:Zn/Graphene/Cu2O/Au. The results revealed that graphene interfacial layer with adequate bandgap and electron affinity offer appreciable efficiency through proper band alignment and suppressed carrier recombination. Moreover, the recommended device contributes exceptional performance parameters: (Jsc, Voc, FF, and η) of (20.13 mA/cm2, 1.207 V, 87.13%, and 21.17%) for minimum PVT defect density of 1 × 1013 cm−3.

Do network characteristics affect systemic risk? Evidence from the European banking system

ABSTRACT Systemic risk is one of the main concerns for banks charged with maintaining overall financial stability. This paper adopts the minimum density method to construct an interbank lending network for European banks and examines how the network structure affects systemic risk. The result reveals that banks positioned at the core of the network exhibit higher levels of systemic risk. Moreover, we find that banks with higher network centrality can show larger systemic risk during times of distress. We demonstrate the robustness of our results by addressing potential endogeneity in the model, replacing network characteristics, and reconstructing the interbank network.

Mechanical properties and oxidation corrosion resistance of phosphate ceramic coating enhanced by SiO2‐BNNSs material

AbstractA method of preparing SiO2‐BNNSs hybrid material by surface modification of boron nitride nanosheets (BNNSs) with SiO2 was proposed to improve the dispersion of BNNSs in the coatings. Then, phosphate ceramic coatings with BNNSs and SiO2‐BNNSs were prepared on stainless steel (304) by spraying. Characterization of BNNSs and SiO2‐BNNSs by X‐ray diffraction, Fourier transform‐infrared, Raman, and scanning electron microscopy proved the success of hybridization. The surface morphology and mechanical properties were conducted to characterize the protective performance of the coating. Simultaneously, the phase composition and electrochemical properties of the coatings after high‐temperature oxidation were studied. The results showed that ceramic coatings had low surface energy with a contact angle of 102.41° when .4 wt.% SiO2‐BNNSs was added. Compared with BNNSs coating, the mechanical properties of SiO2‐BNNSs coating were significantly enhanced, the hardness of .4 wt.%SiO2‐BNNSs coating was as high as 170 HV, and the interface bonding strength was 12.24 MPa. For the oxidation corrosion resistance, .4 wt.% SiO2‐BNNSs coating under oxidation at 400°C for 50 h had the minimum corrosion current density and maximum impedance, which were .864 μA/cm2 and 177 kΩ/cm2, respectively, this indicated that SiO2‐BNNSs coating could still maintain excellent oxidation corrosion resistance under high‐temperature conditions for a long time.

Production of [formula omitted]Xe and [formula omitted]Xe via neutron activation of 128Xe and 130Xe at ILL-RHF and NCBJ-MARIA high-flux reactors

The long-lived xenon isomers 129mXe and 131mXe are of interest for the GAMMA-MRI project, which aims at developing a novel imaging modality based on magnetic resonance of polarized unstable tracers. Here, we present the steps leading to and following the production of these two isomers via neutron irradiation of highly-enriched 128Xe and 130Xe gas samples at two high-flux reactors, the High-Flux Reactor (Réacteur à haut flux, RHF) at the Institut Laue-Langevin (ILL) and the MARIA reactor at the National Centre for Nuclear Research (NCBJ). We describe the experimental setups and procedures used to prepare the stable xenon samples, to open the irradiated samples, and to transfer xenon isomers into reusable transport vials. The activity of 129mXe and 131mXe was measured to be in the range of tens of MBq per sample of 0.8(1)mg, and was proportional to thermal neutron flux density. A small activity of unstable contaminants was also visible in the samples, but their level is not limiting for the GAMMA-MRI project’s objectives. In addition, the minimum thermal neutron flux density required to produce 129mXe and 131mXe sufficient for the project could be also determined.

Disappearing Solar Wind at Mars: Changes in the Mars‐Solar Wind Interaction

AbstractOn 26 December 2022 the solar wind density dropped by over an order of magnitude and remained low for about a day. We have utilized in‐situ plasma measurements made by the Mars Atmosphere and Volatile EvolutioN mission to determine how this change affected the Mars‐solar wind interaction. During this time period, on inbound orbit segments, MAVEN sampled the terminator ionosphere, which switched from a magnetized to unmagnetized state immediately following the minimum in solar wind density. The magnetic field amplitude was typically 5–10 nT within the upper ionosphere prior to the event and consistently &lt;1 nT after. During the event the magnetic pressure dominated immediately above the ionosphere while within the ionosphere the ionospheric plasma pressure dominated. The high altitude terminator ionosphere remained in this unmagnetized state throughout the event, suggesting that it was the new equilibrium state of the system. The terminator upper ionosphere returned to its original magnetized state once the solar wind density had recovered. The outbound orbit segments sampled the dayside subsolar region which remained magnetized throughout the event: the magnetization state of the ionosphere varied locally, dependent upon the solar zenith angle and corresponding incident solar wind dynamic pressure. Such conditions are different to the commonly reported unmagnetized ionospheric state at Venus during solar maximum conditions, where the interplanetary magnetic field is repelled from the entire dayside ionosphere. Drastic changes in the upstream solar wind are able to change the Mars‐solar wind interaction state on timescales less than one MAVEN orbit (∼3.5 hr).

Re-entrant percolation in active Brownian hard disks.

Non-equilibrium clustering and percolation are investigated in an archetypal model of two-dimensional active matter using dynamic simulations of self-propelled Brownian repulsive particles. We concentrate on the single-phase region up to moderate levels of activity, before motility-induced phase separation (MIPS) sets in. Weak activity promotes cluster formation and lowers the percolation threshold. However, driving the system further out of equilibrium partly reverses this effect, resulting in a minimum in the critical density for the formation of system-spanning clusters and introducing re-entrant percolation as a function of activity in the pre-MIPS regime. This non-monotonic behaviour arises from competition between activity-induced effective attraction (which eventually leads to MIPS) and activity-driven cluster breakup. Using an adapted iterative Boltzmann inversion method, we derive effective potentials to map weakly active cases onto a passive (equilibrium) model with conservative attraction, which can be characterised by Monte Carlo simulations. While the active and passive systems have practically identical radial distribution functions, we find decisive differences in higher-order structural correlations, to which the percolation threshold is highly sensitive. For sufficiently strong activity, no passive pairwise potential can reproduce the radial distribution function of the active system.

Remora optimization algorithm-based adaptive fusion via ant colony optimization for traveling salesman problem

The traditional ant colony optimization (ACO) is easy to fall into local optimal when solving large-scale traveling salesman problem (TSP), and the convergence speed is slow. In order to enhance the local search ability of ACO, speed up the efficiency of ACO and avoid the premature problem, this paper proposes a novel remora optimization algorithm-based adaptive fusion via ant colony optimization for solving TSP. Firstly, an improved K-means clustering method is used to obtain the best clustering results and the optimal solutions of each class quickly by adaptive clustering strategy based on the maximum and minimum distance and class density. By using an improved Remora optimization algorithm, adjacent classes are fused to effectively improve the accuracy of the initial solution. In addition, the initial solution is optimized by the k-opt strategy. Finally, the random recombination strategy is used to recombine the pheromone and random excitation to make the algorithm jump out of the local optimal as far as possible and improve the accuracy of the algorithm. The experimental results show that the proposed algorithm not only guarantees the accuracy of solution, but also improves the stability when solving large-scale TSP.

Electrospun nylon 6/hyaluronic acid/chitosan bioactive nanofibrous composite as a potential antibacterial wound dressing.

Hyaluronic acid (HA) and chitosan (CS), as natural biomaterials, display excellent biocompatibility and stimulate the growth and proliferation of fibroblasts. Furthermore, nylon 6 (N6) is a low-cost polymer with good compatibility with human tissues and high mechanical stability. In this study, HA and CS were applied to modify N6 nanofibrous mat (N6/HA/CS) for potential wound dressing. N6/HA/CS nanofibrous composite mats were developed using a simple one-step electrospinning technique at different CS concentrations of 1, 2, and 3 wt%. The results demonstrated that incorporating HA and CS into N6 resulted in increased hydrophilicity, as well as favorable physical and mechanical properties. In addition, the minimum inhibitory concentration and (MIC) optical density techniques were used to determine the antibacterial properties of N6/HA/CS nanofibrous composite mats, and the results demonstrated that the composites could markedly inhibit the growth of Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli. Because of its superior mechanical properties, substantial antimicrobial effects, and hydrophilic surface, N6/HA/CS at 2 wt% of CS (N6/HA/CS2) was chosen as the most suitable nanofibrous mat. The swelling, porosity, gel content, and in vitro degradation studies imply that N6/HA/CS2 nanofibrous composite mat has proper moisture retention and biodegradability. Furthermore, the N6/HA/CS2 nanofibrous composite mat was discovered to be nontoxic to L929 fibroblast cells and to even improve cell proliferation. Based on the findings, this research offers a simple and rapid method for creating material that could be utilized as prospective wound dressings in clinical environments.

Денситометрическая оценка минеральной плотности костной ткани у пациентов молодого возраста с лимфомой Ходжкина

Hodgkin’s lymphoma is more often diagnosed in young patients. One of the late complications of pathogenetic therapy of Hodgkin’s lymphoma is osteopenia/osteoporosis and the increased risk of low-energy fractures. Conducting densitometry in young patients in order to assess the bone tissue condition is advisable, but its clinical assessment remains difficult. At the same time, early diagnosis and prevention of bone mineral density decrease in patients with Hodgkin’s lymphoma who received antitumor therapy are very relevant. The purpose — to study the features of densitometric indicators for the verification of osteopenia / osteoporosis in young patients with Hodgkin’s lymphoma. Material and methods. 63 people were included in the study, 33 of them were patients with Hodgkin’s lymphoma who received pathogenetic therapy, and 30 people the control group — healthy volunteers. Bone mineral density was measured in all patients using the HOLOGIC (Hologic Inc., Bedford) in the lumbar spine (L1–L4) and in the hip area (the total area of the hip and hip neck). Criteria such as minimum bone mineral density, T-criteria and Z-criteria for young patients with Hodgkin’s lymphoma were determined. Results. In the group of patients with Hodgkin’s lymphoma, a decrease in bone mineral density is significantly more often recorded in all measurement areas, as well as the Z-criterion in the lumbar spine. Regretfully, in young patients the T-criterion can only be used given a more intensive mineralization of bone tissue than in older people and the presence of additional risk factors for osteoporosis (PCTs, glucocorticosteroids, decreased androgenic and fertile function). In patients with HL who received pathogenetic therapy, a decrease in the T-criterion to osteopenia is more often observed in the proximal femur. Conclusion. In many cases, modern capabilities for osteoporosis diagnostic allow correcting mineral metabolism in bone tissue and preventing the development of complications in young patients with Hodgkin’s lymphoma.

The influence of the environment on the diversity of Euglena species and their abundance in the lagoon of Nador-Morocco

The main objective of this work is to study the spatial and temporal evolution and distribution of Euglena species in the Nador lagoon. The study is based on four sampling stations and covers two specific seasons, namely spring and summer 2018. Euglenes belonging to the genus Euglena are particularly interesting and well known in the field of research, due to their great diversity in terms of pigmentation, size and morphological characteristics. Samples taken at each of the four sampling stations were carefully identified morphologically using an inverted light microscope. In total, five species belonging to the genus Euglena were identified, namely: Euglena viridis O.F. Müller 1786, Euglena Caudata Hübner 1886, Euglena Proxima P.A. Dangeard 1902, Euglena tuberculata Svirenko 1915, Euglena sp. Quantitative analysis of the species collected reveals some interesting results. The maximum cell density was recorded at station 4, located near the wastewater treatment plant, with a value of 55 cells per litre during the summer of 2019. In contrast, the minimum cell density was recorded at the same station 4, corresponding to Kariat Arekmen, with a value of 5 cells per litre during the spring period of 2019. These observations highlight significant variations in Euglenes cell density depending on geographical location and season.

HFTCRNet: Hierarchical Fusion Transformer for Interbank Credit Rating and Risk Assessment.

As a prominent application of deep neural networks in financial literature, bank credit ratings play a pivotal role in safeguarding global economic stability and preventing crises. In the contemporary financial system, interconnectivity among banks has reached unprecedented levels. However, many existing credit risk models continue to assess each bank independently, resulting in inevitable suboptimal performance. Thus, developing advanced neural networks to model intricate temporal dynamics and interconnected relationships in the banking system is essential for an effective credit rating and risk assessment learning system. To this end, we propose a novel hierarchical fusion transformer for interbank credit rating and risk assessment (HFTCRNet), which includes the long-term temporal transformer (LT 3 ) module, short-term cross-graph transformer (STCGT) module, attentive risk contagion transformer (ARCT) module, and hierarchical fusion transformer (HFT) module to capture the long-term growth trajectories of banks, the short-term interbank network variance, the potential propagation of risks within interbank network, and integrate these information hierarchically. We further develop an interbank credit rating dataset, encompassing quarterly financial data, interbank lending networks, and key indicators such as credit ratings and systemic risk (SRISK) for 4548 banks from 2016Q1 to 2023Q1. Notably, we also adapt the minimum density algorithm to stabilize the interbank loan network over time, aiding in the analysis of long-term and short-term network effects. Our learning system uses semi-supervised learning to handle labels of varying sparsity, integrating credit ratings and SRISK for a comprehensive assessment of individual bank creditworthiness and systemic interbank risk. Extensive experimental results on our interbank dataset show that HFTCRNet not only outperforms all the baselines in terms of credit rating accuracy but also can evaluate the systemic risk within the interbank network. Code will be available at: https://github.com/AI4Risk/HFTCRNet.

DIFERENTES LOTES DE NÁUPLIOS DE Litopenaeus vannamei (BOONE, 1931) EM LARVICULTURA COMERCIAL

The study aimed to evaluate the influence of diferente batches of Litopenaeus vannamei nauplii on production variables. Four cultures of 20 days each of commercial hatchery were carried out. Each cycle had different batches of nauplii and all management and laboratory conditions were identical for the four cultures. The nauplii were randomly distributed in 15m3 culture tanks with storage at a minimum density of 200 nauplii/L and a maximum density of 217 nauplii/L. Temperature, salinity and pH parameters were measured daily. Analysis of naupliar phototaxism was carried out using a beaker and a lamp. At the end of culture, the postlarvae were harvested and transferred to 500-liter boxes. Subsequently, production and survival data were obtained from the m_sample value. The different batches were evaluated individually within each hatchery, with no comparison between cultures. Batches C1, B1, B2 and C2 had better productivity averages in cultures I, II, III and IV, respectively. Therefore, it can be concluded that different batches of nauplii influence different productive responses

Studies on Fish Feed Formulation

Good nutrition in animal production systems is essential to produce a healthy, high-quality product economically. In fish farming, nutrition is critical because feed represents 40-50% of the production costs. Fish nutrition has advanced dramatically in recent years with the development of new, balanced commercial diets that promote optimal fish growth and health. The development of new species-specific diet formulations supports the aquaculture (fish farming) industry as it expands to satisfy increasing demand for affordable, safe, and high-quality fish and seafood products Conducted experiments on studies on fish feed formulation at CIPHET, Ludhiana. The present study evaluates the importance of fish feed pellets as alternative feed ingredients for fish feed preparation. Commonly available materials i.e., debittered mustard oil cake, fish meal, maize powder, and mineral powder mixture. The crude protein content of the feed ingredients ranged from 10 to 60 % and the crude fat contents were recorded as 4 to 12%. Crude fiber contents were between 1 and 8 % and ash contents ranged from 6.9 to 38 %. In this study, results showed that the minimum volume of pellets is 700.4 mm3 and maximum volume is 925.504 mm3 and the minimum density of pellets is 0.00092 g. mm-3 and the maximum density of pellets is 0.00107 g. mm-3 of the pellets. The 0.5838g weight of the pellet will take less time to dissolve completely when compared with more 0.9127g weight of the pellet.

Identifying immunological markers for bowel cancer

The role of immunological processes in the pathophysiology of colorectal cancer has received a lot of attention lately and has been extensively researched. Immune processes are significantly regulated by cytokines and antimicrobial peptides (AMP). Numerous studies have demonstrated the significance of cytokines in the prognosis and surveillance of malignant oncological illnesses. In group II, the blood serum concentration of Calprotectin was found to be greater in 13 patients (92.0%) and lower in 1 patient (8.0%) compared to control limits (χ=24.27, p&lt;0.001). The obtained results show that, in comparison to the control group, the concentration of Calprotectin rises statistically consistently by 3.5 times, with a coefficient of integrity of p&lt;0.001. According to the data, there is a statistically significant rise in Calprotectin concentration (3.5 times higher than in the control group) with a p-value of less than 0.001. The average mathematical density of this indicator is 3.42±0.48 pg/ml, the minimum density is 0.7 pg/ml, and the maximum thickness is 6.1 pg/ml.

Movement ecology and minimum density estimates of red foxes in wet grassland habitats used by breeding wading birds

The red fox (Vulpes vulpes) is a widely distributed generalist meso-predator implicated in declines of wading bird populations. In the wet grassland habitats where waders breed, wildlife managers work to mitigate fox predation risk to waders during the nesting period through lethal and non-lethal control methods. However, limited knowledge on fox movement ecology in these habitats makes it difficult to design effective management strategies. We used GPS telemetry to understand fox home range size, daily activity and movement patterns, and how these metrics may vary among wet grassland sites with different management. We caught and GPS-tagged 35 foxes in the March–June wader nesting period on two wet grassland sites in central southern England; Britford during 2016/17 and Somerley during 2018/19. We estimated home range areas from location data using local convex hulls, and from these estimates we derived the minimum fox density at each site and year. Daily activity patterns and movement behaviour of each fox were obtained using both telemetry and trail camera data. Mean fox home range area at Britford (0.21 km2, SE = 0.025) was significantly smaller than at Somerley (0.68 km2, SE = 0.067), and estimated minimum densities were around four times higher (Britford = 10.6 foxes/km2, Somerley = 2.4 foxes/km2). Foxes were more active and moved faster during twilight and night hours, but both telemetry and camera data indicate they were also active for one-third of daylight hours. Distances moved per day were variable between foxes but generally smaller at Britford. We also found evidence for dispersal during spring, with movements of up to 19 km per day. Home ranges at both wet grassland sites were smaller than comparable sites elsewhere. These indicated foxes were living at exceptionally high densities at Britford, where there is no fox control, increased food availability and where waders no longer breed. Spatio-temporal movement patterns were closely related to home range metrics, with higher levels of fox activity at Somerley, where home ranges were larger. The movements of itinerant and dispersing foxes during the nesting period suggests that lethal control would need to be very intensive to be effective. The likely anthropogenic food subsidy of fox density at Britford suggests that controlling access to similar food resources would help reduce predation pressure on breeding waders.

Dislocations in Crystalline Silicon Solar Cells

Dislocation is a common extended defect in crystalline silicon solar cells, which affects the recombination characteristics of solar cells by forming deep‐level defect states in the silicon bandgap, thereby reducing the lifetime of minority carrier. Hence, reducing the impact of defects on device performance is an effective strategy to optimize the performance of photovoltaic devices. This article reviews the observation and engineering of dislocation in Si solar cell. The structure and deformation of Si can be directly observed by chemical etching combined with electron microscopy. Also, more information about dislocation is obtained indirectly by monitoring the electrical and optical properties of Si. The classification, density, distribution of dislocations, and their interactions with other defects in Si can affect the lifetime of minority carriers and thereby reduce the performance of Si solar cells. In order to achieve higher cell efficiency, crystals with less or even no dislocation should be obtained. In addition to the specification of controlling the relevant parameters during the growth of silicon ingots to obtain the minimum dislocation density, it is necessary to study the behavior of dislocation in Si wafers under the combined action of external stress, temperature, and other defects.

Effect of Cell Density of a Methacrylic Acid-Based Hydrogel Implant on Embedded Islet Function and Viability.

Subcutaneous delivery of islets in a methacrylic acid-based hydrogel may offer a functional cure for type 1 diabetes. Here we show in mice that the hydrogel is able to provide sufficient vasculature to support islet function and viability, when islets are used at a low islet volume fraction (i.e., cell density). The Krogh cylinder model was used to mathematically estimate the effect of implant volume, for a fixed islet dose (600 islet equivalents [IEQ]), on the minimum vessel density required to maintain sufficient pO2 within the graft. Modeling suggested that 200 μL implants would have low enough islet densities and enough vessels to have islets remain viable, but that 50 μL implants would not; this was confirmed experimentally through measurement of glucose level in streptozotocin-induced diabetic severe combined immunodeficiency disease (SCID/bg) mice, comparing 200 and 50 μL implants, both with 600 IEQ. Vessel densities were ∼20-30 vessels/mm2 independent of implant volume and vessels were sufficient to increase subcutaneous oxygen tension, as measured with microcapsules containing oxygen sensitive material (a platinum [Pt] porphyrin); both these results were determined without cells. These results are useful in thinking about the scale-up of this system to humans: to maintain a low islet density (∼0.5%), many more islets will require attention to the subcutaneous implant configuration to satisfy the oxygen needs of the cells.

Understanding the behaviour of magnetic field distribution of railgun under transient conditions using finite element method

The magnetic field distribution in the rails is a crucial factor in comprehending railgun behaviour. The projectile's rapid movement has a significant impact on the magnetic field. If the dispersion of the magnetic field conclusions regarding the conductors are known suitable methods can be used to sketch the magnetic field distribution. The railgun operates on the premise that a high current flow through the rails and armature will create a strong magnetic field. As a result, before designing magnetic shielding, it is necessary to study the features of the magnetic field distribution. The shape of rail and armature cross section is very essential in rail gun design as it determines the magnetic field distribution over rail and armature. The rail gun geometries with rectangular, convex and concave rail cross-sections are compared and simulated using finite element method (FEM). This method is used to determine the magnetic field distribution over rail and armature by sweeping armature position for different rail cross sections. It is observed that for the different rail/armature shapes like rectangular, convex and concave shapes, the C shaped convex armature possesses strong magnetic fields with minimum current density concentration at the throat and trailing end of the armature. From simulation, it can be shown that the magnetic flux density is a descending function of the central angle. The electromagnetic (EM) rail gun launching mechanism was therefore proven to be compatible with the circular concave armature.