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Pulmonary embolism triggered by cold agglutinin syndrome in mycoplasma pneumoniae pne...
Zeyu Wang
Ni Yang

Zeyu Wang

and 5 more

May 14, 2022
Mycoplasma (M.) pneumoniae is a common pathogen causing respiratory infections in children. Pulmonary embolism is a rare complication that may be life-threatening if not diagnosed early and treated promptly. Here, we report the case of an 11-year-old patient with pulmonary embolism associated with M. pneumoniae pneumonia. The patient developed uncorrectable hypoxemia and received venovenous extracorporeal membrane oxygenation treatment. Although the mechanism of thrombosis after M. pneumoniae infection remains unknown, an increase in the cold agglutinin titer indicates that cold agglutinin syndrome might be the mechanism of this pathological change. We thought that patients who have positive cold agglutinin after M. pneumoniae infection should be monitored for the possibility of thrombosis formation.
Impulse oscillometry in preschool children with persistent asthma can predict spirome...
Alberto Vidal Grell
Ramiro González Vera

Alberto Vidal Grell

and 8 more

May 14, 2022
Background: Lung function in children with persistent asthma may be impaired during preschool and school ages. The aim of this study was to describe if some preschool IOS parameters are related to spirometry alterations on reaching school age. Methods: 66 children under six years old diagnosed with persistent asthma were studied prospectively with IOS during their preschool years and spirometry at school age. Results: The mean age was 4.9 years at the first evaluation and 7.9 years at the second evaluation, and 59.1% were male. During preschool, R5, Fres, AX, and D5-20 were found to have diagnostic accuracy (AUC>0.7) for predicting altered spirometry during school age (defined as FEV1 and/or FEV/FVC and/or FVC values below the lower limit of normality according to Quanjer predictive values). AX, D5-20, and R5 had the best LR+ to increase the probability of altered spirometry (50, 10, and 7.1, respectively). R5 was the best IOS parameter for discriminating bronchodilator response (BDR) in schoolchildren (AUC=0.7, LR+ = 3.7). Abnormal IOS increases the risk of having abnormal spirometry (RR=12.7, p= 0.002). This risk is even higher in atopic patients (RR= 21, p=0.003). Conclusion: The findings of this study indicate that some IOS parameters between 3 and 5 years of age are useful for predicting abnormal spirometry and BDR at school age.
Predictive factors of egg allergy clinical outcomes in infants and young children
Xiaoyan Mo
Jiajia Lv

Xiaoyan Mo

and 2 more

May 14, 2022
Aim: The aim of the present study was to explore the tolerance march in children and establish probable factors that affect the prognosis of an egg allergy (EA). Methods: Two hundred children 6 months to 2.5 years old with atopic dermatitis (AD) were recruited into our study from 2018 to 2019. EA was diagnosed based on medical history, the skin prick test (SPT), and the oral food challenge test (OFC) ,EA was diagnosed in 78,among those, 7 were allergic only to egg yolk (OnlyEYA), 20 to egg white (OnlyEWA), and 51 to whole egg (WEA). Logistic regression analysis was used to detect the disease course and related risk factors of outcomes. The receiver operating characteristic curve was used to establish a predicting model. Results:The Scoring Atopic Dermatitis score in the WEA group was more severe and persistent than that in the other groups. Forty-three cases of EA developed clinical tolerance (average age, 32.3 ± 8.7 months). The tolerance rate of EYA was 75.9% and EWA was 56.3%. The SPT wheal diameter at initial diagnosis (SPT diag) was the risk factor for persistent EA. The SPT wheal diameter after 6 months (△SPT 6mo) in the tolerant group decreased markedly compared to that in the persistent EA group. Tolerance was higher when △EW-SPT 6mo ≥ 39.5% or △EY-SPT 6mo ≥ 27%. Conclusion: The initial SPT diag and SPT 6mo values were significantly correlated with and can predict outcomes of EA. Key words: Egg allergy, atopic dermatitis, outcome, related factors.
The rising cesarean section rate in China: a call for action
Rui-Hong Xue

Rui-Hong Xue

May 14, 2022
Commentary
Yellow fever virus investigation in tissues of vampire bats Desmodus rotundus during...
Marli do Carmo Cupertino
Taciana de Souza Bayão

Marli do Carmo Cupertino

and 7 more

May 14, 2022
In the last decade a large outbreak of Yellow Fever (YF) has been observed in Brazilian Atlantic Forest region, that is traditionally non-endemic area. In this scenario, the role of wild mammal species as YF reservoirs can be questioned, especially the hematophagous bat, endemic to the Atlantic Forest. So, the objective was to analyze molecularly the presence of the YF virus (YFV) in hematophagous bats during a YF outbreak in Brazil. Twenty-one samples were collected from seven adults’ male hematophagous bats Desmodus rotundus. Due YFV is considered a viscerotropic and neurotropic virus, samples of liver, kidney and brain were collected and molecularly analyzed using the RT qPCR technique. The animals were captured according ethical protocols during a YF outbreak in Brazil in 2017 from a region of the Brazilian Atlantic Forest. The results revealed that the analyzed tissue samples were not infected with the YFV. The negative results for this species of bats allow us to infer that other animals may be reservoirs of this virus in this ecosystem and are probably not being identified. Therefore, health surveillance actions are essential to monitor the role of wild animals in the yellow fever dissemination in Brazilian Atlantic Forest and alert to possibility to new geographic amplification of areas where YF occur. This research encourages the news search about role of wild animals in the YFV transmission and reinforce the importance of epidemiological surveillance in the transmission of human infectious disease.
FcRn-targeting and ROS-responsive Fedratinib-incorporated Nanoparticles Alleviate Ast...
Weimin Sun
Shijie SONG

Weimin Sun

and 11 more

May 14, 2022
Background: Reducing the number of airway eosinophils is critical for treating eosinophilic asthma. The JAK2-STATs pathway is essential for myelopoiesis of eosinophils and production of type I and II cytokines, and therefore can be a novel target for intervention of eosinophilic asthma. Here, we aimed to demonstrate the apoptosis-inducing potential of Fedratinib (FDTN), a JAK2-specific inhibitor, and test the efficacy of the ROS-responsive, FcRn-targeting and FDTN-caged nanoparticles on eosinophilic asthma alleviation. Methods: The apoptosis-inducing potential of FDTN in eosinophils from asthma patients was assessed by flow cytometry, and light and electron microscopy. FDTN-caged nanoparticles (NPs-FDTN) were designed to ROS responsive and modified with Fc portion of IgG through the avidin-biotin interaction. The biological availability of NPs-FDTN was assembled via biochemical and immunological analysis, and the therapeutic effects were investigated in eosinophilic asthma model mice by comparing free FDTN and budesonide treatment. Results: FDTN blocked the JAK2/STAT5 pathway and activated the intrinsic pathway of apoptosis in eosinophils in a concentration-dependent manner. NPs-FDTN crossed the epithelial barrier via the Fc/FcRn-mediated transcytosis, bypassed the lysosome and entered the inflammatory microenvironment. Caged FDTN was released from the nanoparticles in the presence of ROS. Compared to free FDTN, the residence time of FDTN in the lung parenchyma was prolonged and the therapeutic effects were improved when delivered in nanoparticles. Conclusion: Ros-responsive, FcRn-targeting and FDTN-caged nanoparticles overcame the airway epithelial barrier and improved the bioavailability on eosinophil apoptosis. This study provides a fancy and safe therapeutic strategy for treatment of eosinophilic asthma.
Successful Management of Scalp Avulsion with Full Thickness Graft
Mohammad Badr Almoshantaf
Sarya Swed

Mohammad Almoshantaf

and 6 more

May 14, 2022
Scalp avulsion injuries are one of the life-threatening traumatic injuries. There are no clear guidelines to determine which reconstructive method is superior to another in each condition. Our case demonstrates that relatively primitive methods like skin grafting can give greater results if done with circumspection.
Outcomes of expanded polytetrafluoroethylene pericardial membrane implantation in lef...
Kevin An R
Nicole Christakis

Kevin An R

and 6 more

May 14, 2022
Objectives Redo sternotomy and explantation of left ventricular assist devices (LVAD) for heart transplantation (HT) involve prolonged dissection, potential injury to mediastinal structures and/or bleeding. Our study compared a complete expanded polytetrafluoroethylene (ePTFE) wrap versus minimal or no ePTFE during LVAD implantation, on outcomes of subsequent HT. Methods Between July 2005 and July 2018, 84 patients underwent a LVAD implant and later underwent HT. Thirty patients received a complete ePTFE wrap during LVAD implantation (Group 1), and 54 patients received either a sheet of ePTFE placed in the anterior mediastinum or no ePTFE (Group 2). Results Baseline characteristics were similar between Groups 1 and 2. Surgeons reported subjective improvements in speed, predictability and safety of dissection with complete ePTFE compared with minimal or no ePTFE. Time from incision to initiation of cardiopulmonary bypass (CPB) were similar between groups (97±38 min vs 89±29 min, p=0.3). Injury to mediastinal structures during the dissection was similar between groups (10% vs 11%, p>0.9). While surgeons reported less intraoperative bleeding in Group 1 (43% vs 61%), this trend did not reach significance (p=0.1). In-hospital mortality, ICU length of stay and hospital length of stay were similar between both groups. Conclusions In patients undergoing LVAD explant-HT, there was a trend towards reduced surgeon reported intraoperative bleeding with ePTFE placement. Despite qualitatively reported greater ease and speed of mediastinal dissection with ePTFE membrane placement, time to initiation of CPB did not differ, likely because surgeons remained cautious, allowing extra time for unanticipated difficulties.
Awake cardiac surgery using the novel Pectoralis-Intercostal-Rectus Sheath (PIRS) Pla...
Antonio Toscano
Eleonora Balzani

Antonio Toscano

and 7 more

May 14, 2022
BACKGROUND Postoperative pain after cardiac surgery is a very important issue and affects recovery, risk of postoperative complications and quality of life. The pain management has been traditionally based on intravenous opioids with growing evidence suggesting the use of opioid-free and opioid-sparing techniques to reduce its adverse effects. CASE PRESENTATION We report the case of a 75-years-old frail patient underwent awake mediastinal revision with subxiphoid access due to deep sternal wound infection using a Pectoralis-Intercostal Rectus Sheath (PIRS) plane block. During the procedure the patient never reported pain receiving acetaminophen 1 g every 8 hours for postoperative pain management without others pain relievers. CONCLUSION Ultrasound guided PIRS block could be an effective and safe analgesic technique to manage sternal and subxiphoid drainage pain in patients undergoing cardiac surgery via subxiphoid approach.
Extended aortic arch repair via simple median sternotomy using a parabronchial approa...
Ryosuke Kowatari
Hanae Sasaki

Ryosuke Kowatari

and 4 more

May 14, 2022
Surgery for extensive thoracic aortic aneurysms is challenging. We report the case of a young woman with Takayasu’s arteritis who developed aortic dissection and was successfully treated with our novel extended arch repair method, which we termed “parabronchial approach”. Surgery was performed via a simple sternotomy. The left pulmonary artery was compressed caudally by a surgical assistant arm typically used for coronary artery bypass grafting. This method simplified the creation of a distal anastomosis to the descending aorta behind the left bronchus. Postoperative computed tomography revealed a distal anastomosis at the sixth thoracic vertebra . This parabronchial approach could reduce the frequency of choosing a highly invasive approach and can be a potential minimally invasive approach in cases requiring extensive thoracic aortic aneurysm repair.
Garcin syndrome in a case of acquired immunodeficiency syndrome: Case report and lite...
Ilad Alavi Darazam
Mohammad Mahdi Rabiei

Ilad Alavi Darazam

and 9 more

May 14, 2022
In this study, we report a parapharyngeal diffuse large Bcell lymphoma in a human immunodeficiency virus (HIV) infected patient which had caused the patient to suffer from Garcin syndrome.
A case of cryptosporidial gastroduodenitis and wasting syndrome in an adolescent with...
Ilad Alavi Darazam
Farahnaz Bidari Zerehpoosh

Ilad Alavi Darazam

and 5 more

May 14, 2022
Cryptosporidium causes watery diarrhea, despite the normal population it might prolonged and life threatening in severely immunocompromised individuals. In the current study, we reported Cryptosporidium gastroduodenitis in 17 years old female with HIV (human immunodeficiency virus).
Durable disease control with apatinib, irinotecan and temozolomide in a case of metas...
Sze Hon Yu
Amanda Kan

Sze Hon Yu

and 6 more

May 14, 2022
Primitive myxoid mesenchymal tumour of infancy (PMMTI) a rare and aggressive soft tissue tumour driven by alteration in the BCOR gene. Localised disease may be cured by surgical resection but metastatic disease often displays suboptimal chemotherapy response. Here we report the course of a patient with widely metastatic PMMTI, where durable disease control was achieved with the combination of apatinib, a VEGFR inhibitor, and chemotherapy with irinotecan/temozolomide.
Hydrogen Storage Capacity of Be2(NLi)2 Cluster with Ultra-short Beryllium-Beryllium D...
Kangkan Sarma
Amlan Kalita

Kangkan Sarma

and 3 more

May 14, 2022
Quantum chemical calculations have been carried out to investigate the hydrogen storage capacity of Be2(NLi)2 cluster which contains ultra-short beryllium-beryllium distance. Calculations reveal that the cluster can take up to 6 H2 molecules reaching a maximum gravimetric density of 16.6 wt%. All the H2 binds at the Li atom with a moderate binding energy which is required for reversible storage of H2. Symmetry adapted perturbation analysis reveals significant contribution of electrostatic and induction and very minor contribution of dispersion towards the total interaction energy. The interaction between the H2 and Li centre is found to possess significant covalency. Molecular dynamics simulations reveal that the H2 molecules are strongly bound at 77K and get slowly released at elevated temperature.
$k$-sparse signal recovery via unrestricted $\ell_{1-2}$-minimization
Shaohua Xie

Shaohua Xie

May 14, 2022
In the field of compressed sensing, $\ell_{1-2}$-minimization model can recover the sparse signal well. In dealing with the $\ell_{1-2}$-minimization problem, most of the existing literatures use the DCA algorithm to solve the unrestricted $\ell_{1-2}$-minimization model, i.e. model $(\ref{my1})$. Although experiments have proved that the unrestricted $\ell_{1-2}$-minimization model can recover the original sparse signal, the theoretical proof has not been established yet. This paper mainly proves theoretically that the unrestricted $\ell_{1-2}$-minimization model can recover the sparse signal well, and makes an experimental study on the parameter $\lambda$ in the unrestricted minimization model. The experimental results show that increasing the size of parameter $\lambda$ in model $(\ref{my1})$ appropriately can improve the recovery success rate. However, when $\lambda$ is sufficiently large, increasing $\lambda$ will not increase the recovery success rate.
Mutual information analysis of mutation, nonlinearity and triple interactions in prot...
Burak Erman

Burak Erman

May 14, 2022
Mutations are the cause of several diseases as well as the underlying force of evolution. A thorough understanding of its biophysical consequences is essential. We present a computational framework for evaluating different levels of mutual information (MI) and its dependence on mutation. We used molecular dynamics trajectories of the third PDZ domain and its different mutations. MI calculated from these trajectories shows that: (i) the multivariate Gaussian distribution of joint probabilities characterizes the MI between residue pairs with sufficient accuracy. Nonlinearities in joint probabilities calculated by tensor Hermite polynomials up to the fifth order contribute insignificantly. (ii) Changes in MI between residue pairs show the characteristic patterns resulting from specific mutations. (iii) Triple correlations are characterized by evaluating MI between triplets of residues, certain triplets are strongly affected by mutation. (iv) Susceptibility of residues to perturbation are obtained by MI and discussed in terms of linear response theory.
An umbrella review and meta-analysis of the use of renin-angiotensin system drugs and...
Amanj Kurdi
Natalie   Weir

Amanj Kurdi

and 2 more

May 13, 2022
Aim To provide a comprehensive assessment of the effect of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor II blockers (ARBs) on COVID-19 related outcomes by summarising the currently available evidence. Methods This was an umbrella review of systematic reviews/meta-analysis conducted using Medline (OVID), Embase, Scopus, Cochrane library and medRxiv from inception to 1st February 2021. Systematic reviews with meta-analysis that evaluated the effect of ACEIs/ARBs on COVID-19 related clinical outcomes were eligible. Studies’ quality was appraised using the AMSTAR 2 Critical Appraisal Tool. Data were analysed using the random-effects modelling including several sub-group analyses. Heterogenicity was assessed using I2 statistic. The study protocol was registered in PROSPERO (CRD42021233398). Results Overall, 47 reviews were eligible for inclusion. Out of the nine COVID-19 outcomes evaluated, there was significant associations between ACEIs/ARBs use and each of death (OR=0.80, 95%CI=0.75-0.86; I2=51.9%), death/ICU admission as composite outcome (OR=0.86, 95%CI=0.80-0.92; I2=43.9%), severe COVID-19 (OR=0.86, 95%CI=0.78-0.95; I2=68%), and hospitalisation (OR=1.23, 95%CI=1.04-1.46; I2= 76.4%). The significant reduction in death/ICU admission, however, was higher among studies which presented adjusted measure of effects (OR=0.63, 95%CI=0.47-0.84) and were of moderate quality (OR=0.74, 95%CI=0.63-0.85). There was no evidence of any significant association between ACEIs, or ARBs and COVID-19 outcomes. Conclusions Collective evidence from observational studies indicate a good quality evidence on the significant association between ACEIs/ARBs use and reduction in death and death/ICU admission, but poor-quality evidence on both reducing severe COVID-19 and increasing hospitalisation. Our findings further support the current recommendations of not discontinuing ACEIs/ARBs therapy in patients with COVID-19.
Adopting combined nitrogen and phosphorus management based on nitrate nitrogen thresh...
Zu jiao Shi
Donghua Liu

Zu jiao Shi

and 6 more

May 13, 2022
The appropriate combined nitrogen and phosphorus fertilization strategy is essential for obtaining higher grain yields while maintaining soil fertility. Here, a long-term split-plot design farmland experiment with five N fertilizer rates combined with four P fertilizer rates was established during 2016–2019 to determine an appropriate nitrate-N threshold in intensive managed winter wheat- summer maize cropping, and then propose the fertilization strategy based on NO3-N threshold to balances crop yield and soil nitrogen supply capacity. The results showed that N fertilizer increased accumulated NO3-N, while the combined phosphate fertilizer at each N rate reduced the accumulated NO3-N to different degrees. With the increasing of planting seasons, the residual soil NO3-N reached a steady-state balance of soil N pool when N application rate was 150–225 kg ha−1 combined 60–120 kg ha−1 P rate. The residual NO3-N threshold was determined as 100 kg ha−1 to maintain N supply capacity and prevent it leaching. Based on it, we recommend 154 kg ha−1 of N and 106 kg ha−1 of P fertilizer in the wheat season, and 162 kg ha−1 of N and 122 kg ha−1 of P fertilizer in the maize season. The optimized fertilizer strategy reduced the fertilizer by 67 kg N ha−1 per year and reduced the residual NO3-N by 34.2% in deep soil while only reducing average yield by 3.1% across crops and years. This study can serve as basis for sustainable solutions for balances grain yields and soil nitrogen supply capacity as well as preventing nitrate pollution in farmland.
Computational resources for simulating under a spatial coalescent model across hetero...
Arnaud Becheler
L. Lacey Knowles

Arnaud Becheler

and 1 more

May 13, 2022
Spatially explicit coalescent models in which the underlying demographic parameters are informed by the environment (either past, present, or temporally and spatially changing environments) provide a framework for hypothesis testing that incorporates geographic information about genetically sampled individuals. This general approach - Integrated Distributional, Demographic and Coalescent (iDDC) modelling - can be used to explain how heterogeneous, dynamic landscapes shape the history and genetic patterns of a species. However, iDDC approaches involve long and complex tasks that often require custom-fit simulators, some coding expertise, and extensive computing resources. Here we introduce several resources that offer improved speed and generality, as well as expand the feasible parameter space for conducting iDDC analyses compared to other software applications. Specifically, QUETZAL-EGGS are C++ iDDC simulators; QUETZAL-CRUMBS is a complementary set of Python tools for simulating on specific landscapes and conducting Approximate Bayesian Computation (ABC) analyses (e.g., prior sampling, geospatial operations, ENM/SDM, visualization); DECRYPT is a framework for automated, biology-informed robustness analysis of the multispecies coalescent model. All these tools and their dependencies for local use or remote computations are made readily available in a Docker container package called QUETZAL-NEST.
ASSESSING SOIL EROSION SUSCEPTIBILITY FOR PAST AND FUTURE SCENARIOS IN SEMI-ARID MEDI...
Gianluigi Busico
Eleonora Grilli

Gianluigi Busico

and 4 more

May 13, 2022
The assessment of soil erosion rate, especially in agricultural lands, represents a fundamental tool for land management planning in the long-term period. In this study, the SWAT model was utilized to simulate soil erosion within a semi-arid watershed in South Portugal. The model was successfully calibrated and validated using real data of streamflow and river sediment transport in four hydrometric stations. Soil erosion susceptibility maps (historical and future) were realized to highlight the evolution of the phenomenon through time. The historical period was confirmed to be the worst one in terms of average soil erosion for each land use, followed by the Representative Concentration Pathways (RCPs) 8.5 and 4.5 scenarios. The main differences in soil loss among the two RCPs will be influenced by the slightly increasing trend of extreme events which will characterize the RCP 8.5, leading to a higher maximum value of soil erosion. Results highlighted the tendency to erosion of Leptosols and of the agro-forestry system (“montado”), which influenced the soil erosion susceptibility distribution of the whole basin. The study confirmed that Leptosols are the most subject to sediment loss due to their intrinsic characteristics, and that “montado” and farmed systems will negatively influence soil erosion rate if anti-erosion actions will not be adopted, stressing the need to identify all aspects responsible for land degradation in Mediterranean watersheds.
Sporadic fetal heart rate accelerations during labour practically rules out acidaemia...
Frida Ekengård
Monika Cardell

Frida Ekengård

and 2 more

May 13, 2022
Abstract Objective: To determine the occurrence of sporadic and periodic accelerations during labour and odds ratio, OR, for acidaemia. Design: Case-control study. Setting: One regional and one university hospital. Sample: Cardiotocograms, CTGs, from 295 neonates with cord blood pH <7.05 born during the second stage of labour, 70 neonates with cord blood pH <7.10 born during the first stage and 731 controls with pH ≥7.15. Method: The last 30-60 minutes of CTG recordings before birth from 365 neonates born with acidaemia and from the corresponding stage in labour for 731 controls were scrutinized. Main outcome measures: Odds ratio with 95% confidence interval for acidaemia at birth. Results: During the first stage, sporadic accelerations were present in 16% of cases and 78% of controls; OR for acidaemia 0.05 (0.02-0.10). In the second stage the corresponding rates were 13% and 60%; OR 0.09 (0.06-0.14). Isolated periodic accelerations were infrequent. A weak negative association with acidaemia was found in the second stage; OR 0.51 (0.30-0.86), whereas it was not significant in the first stage; OR 0.24 (0.04-1.4). Less than two sporadic accelerations were associated with an increased risk of acidaemia despite normal fetal heart rate variability (5-25 beats per minute, OR 10.3 (7.2-14.8)). Conclusions: Sporadic accelerations indicate a very low probability of acidosis but are absent in 40% of fetuses with normal pH during a 30-60 minutes second stage recording. Tweetable abstract: Sporadic, but not periodic, accelerations indicate normal fetal pH. This should be a part of CTG guidelines.
“ Homology Modeling of Rab11 Protein of Retina involved in Choroideremia (Homo sapien...
Smita Singh
Nabya Nehal

Smita Singh

and 1 more

May 13, 2022
Choroideremia (CHM), is caused by a defect on the X gene which prohibits the body from making RAB Escort Protein-1, or REP-1, which further lead vision lost. The biological role of RAB Escort Protein-1 (REP-1) determine by homology modeling. In this research work the structure of Rab11 was predicted using Geno3d server. Ramachandran plot obtained by Geno 3-D server to estimate the effect of amino acid. The predicted structure was visualized through different visualization tools such as Pymol, Rasmol, and Swiss-pdb viewer. The active site was predicted through Q-site finder for further drug discovery and development for said disease.
Impact of different destocking strategies on the resilience of dry rangelands
Toyo Vignal
Mara Baudena

Toyo Vignal

and 3 more

May 13, 2022
Half of the world’s livestock live in (semi-)arid regions, where an important proportion of the population relies on animal husbandry for survival. However, overgrazing can lead to land degradation and subsequent socio-economic crises. Sustainable management of dry rangeland requires suitable stocking strategies and has been the subject of intense debate in the last decades. Our goal is to understand how variations in stocking strategies affect the resilience of dry rangelands. We describe the rangeland dynamics through a simple mathematical model consisting of a system of coupled differential equations. We assume that the livestock density is limited by forage availability only, which is itself limited by water availability. We model processes typical of dryland vegetation as a strong Allee effect, leading to bistability between a vegetated and a degraded state, even in the absence of herbivores. We study analytically the impact of varying the stocking density and the destocking adaptivity on the resilience of system to the effects of drought. By using dynamical systems theory, we look at how different measures of resilience are affected by variations in strategies. We find that: 1)Increasing the stocking density decreases the resilience, giving rise to an expected trade-off between productivity and resilience. 2)There exists a maximal sustainable livestock density above which the system can only be degraded. This animals carrying capacity is common to all strategies. 3) Higher adaptivity of the destocking rate to available forage makes the system more resilient: the more adaptive a system is, the bigger the losses of vegetation it can recover from, without affecting the long term level of productivity. The first two results emphasize the need for adapted dry rangeland management strategies, in order to prevent degradation resulting from the conflict between profitability and sustainability. The third point offers a theoretical suggestion for such a strategy.
Numerical investigation of Magnetic Pulse Welding of D9 Steel Tube to SS316LN End Plu...

M. R. Kulkarni

and 5 more

May 13, 2022
Conventional mesh-based numerical methodologies cannot accurately simulate high-speed impact welding due to extreme distortion of mesh. Therefore, a smoothed particle hydrodynamics (SPH) based methodology is implemented to study the welding morphology and jetting phenomenon during magnetic pulse welding (MPW) of D9 clad tubes and  SS 316LN end plugs after carrying out electromagnetic and structural deformation analysis using Lagrangian Finite element method. Different experimental parameters like taper angle, taper length, stand-off distance and discharge energies are varied to minimise leak-tightness. Discharge voltage of 17 kV and 18 kV and taper angle of 8 degrees is observed to be best suited during the experiment. Simulation results are validated with experimental observations. Furthermore, the joints are tested with the help of various non-destructive and destructive techniques. Uniformity at the joint interface is established by X-ray computer tomography. Moreover, the hydraulic pressure burst test shows failure in the unwelded region at the burst pressure of 105 MPa. Therefore, the current work discusses the applicability of the MPW technique as an alternative method to create a D9 tube to SS 316 LN end plug for a fast breeder reactor and the SPH technique on successfully reproducing experimentally observed interface morphology.
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