bluuebunny/crossref_metadata_2025 huggingface dataset:
Management of the waste of construction and demolition
Authors: Ostyakova A V , Mazurin D M
Published: January 2021

The problem of accumulation, transport and disposal of waste is currently the cause of environmental degradation of territories, so it is relevant. The main method of waste disposal in Russia is landfill disposal without additional disposal methods, including recycling. In recent years, technologies for handling construction and demolition waste have been developed so that they can be recycled after processing as raw materials, for example, in the construction industry or in road repairs. This will save primary natural resources and energy. The article uses the example of a specific project for the reconstruction of the building in Moscow to present the technology for handling of the construction and demolition waste during the dismantling of a building with the preservation of the facade wall. The classification of waste according to the Federal classification catalog of waste is given, the volume of waste generated is calculated, the term and organization of their temporary storage on the construction site is given, and the possibility and options for secondary use of this waste are analyzed. Based on the comparison of options, the route scheme for transportation of the construction and demolition waste outside the construction site to the landfill, where the recovery complex and the crushing complex are located. There the waste will be prepared for recycling.
Dynamic and kinematic conditions for designing water channels
Authors: Qosimov Jakhongir , Nasritdinova Umida , Nasritdinov Axmadjon
Published: January 2021

Studies are conducted for design institutes in which the mating structures of pumping stations (PS) are designed. In the regional conditions of the Republic of Uzbekistan during the operation of the PS, of particular importance is the problem of protecting equipment from pumps and fins, as well as the stability of water supply facilities and the creation of favorable hydraulic conditions for supplying flow to the pumps. The main factors in the conditions of flow inlet are calculations related to suspended particles.
Hydraulic characteristics of the water flow under the conditions of stationary inward flow over pipelines with protection coating
Authors: Bryansky Ilya , Bryanskaya Yuliya , Yumasheva Maria
Published: January 2021

While passing through waterbodies the pipeline crossings are affected by the inward flow. It might lead to soil erosion near it, and objects floating in this flow can cause damage of the pipeline, increasing risks of collapse. There are several types of protective coatings that are used on the pipelines, including the flexible protective concrete pavement (mats). Experience has shown that partial erosion of soil foundation can cause flipping of the blocks in first row of the protective coating that would result in its wrapping. This article presents the results of experimental research of hydraulic characteristics of water flow while flowing over two types of flexible concrete mats UGZBM-S and UGZBM placed crosswise the inward flow, that protect the pipeline. We’ve also determined the levels of free surface above differently buried pipeline crossings protected with two types of flexible concrete pavements under the conditions of stationary inward flow.
Influence of the drag coefficient on the maximum pressure of water hammer
Authors: Jonkobilov Ulugmurad , Jonkobilov Sobir , Tashmurza Yuldashev , Xoshiyev Shukhrat
Published: January 2021

The article presents the results of theoretical and experimental studies of the effect of hydraulic friction on the maximum increase in pressure during water hammer. To solve the problem of determining hydraulic friction along a pressure pipe, the telegraph equation was adopted as a mathematical model. As a result of solving the adopted equation, dependence is obtained for calculating the energy loss in a non-stationary process. The calculations of the proposed formula are in good agreement with the experimental data of the author. This proves the legitimacy of the obtained dependence of the author and provides an accurate calculation of pipes for strength during impact and resource saving of pipe material
Studying the hydrodynamic conditions of fluids in reservoir conditions and assessing their influence on the accumulation and placement of hydrocarbon deposits
Authors: Shoymuratov Tuychi , Yarboboyev Tulkin , Jurayev Fazliddin , Shodiyev Bobur
Published: January 2021

The article discusses the study of the behavior of reservoir fluids and the influence of the hydrodynamic situation on the accumulation and conservation of hydrocarbon deposits in the explored structures of the Beshkent trough. The main attention is paid to studying the value of the potential energy of fluids by mapping them at different points in the reservoir to determine the path of formation water and the possible hydrocarbon deposits associated with them. The places of their most probable accumulation are forecasted and recommendations are given for the implementation and adoption of optimal decisions on the targeted conduct of prospecting and exploration.
Strengthening technology and modeling of dams from reinforced soil
Authors: Glovatsky Oleg , Hamdamov B , Bekchanov Fakhriddin , Saparov Azamat
Published: January 2021

The aim of the work is to develop a methodology and technique for modeling reinforced soil for further use and application in hydraulic facilities to ensure their stable operation. The objectives of the study are to substantiate the efficiency of using dams of large canals made of reinforced soil at hydraulic structures of pumping stations of the Republic of Uzbekistan, taking into account local conditions, developing recommendations for the rational design of retaining walls and dams from reinforced soil. To achieve this goal, it is necessary to solve the problems of coordinating the operating modes of the pumping station with the introduction of retaining walls and dams from reinforced soil on full-scale structures. The article discusses the implementation of the method of building them in the management of water distribution on irrigation systems in Bukhara and Kashkadarya regions. The theoretical foundations of modeling and design of test stands for the study of volumetric models of dams of large channels made of reinforced soil have been developed. Studies on volumetric models of dams made of reinforced soil were carried out in compliance with the criteria of approximate similarity, which made it possible to obtain new physical ideas about the operation of structures at the stage of destruction. The conducted studies of the models of the built-up part of the dams made it possible to estimate the bearing capacity by the value of the breaking load of the reinforced model to the value of the breaking load of the unreinforced (reference) model.

The presence of reinforcement in the soil increases the bearing capacity of the model in comparison with the unreinforced one: even with the volume percentage of reinforcement μ = 0.064%, the hardening coefficient is equal to Chard = 2.60; with μ = 0.032% Chard = 1.70-2.07. With the same percentage of reinforcement μ = 0.032%, an increase in the vertical spacing of the reinforcement leads to a decrease in the bearing capacity by 12-15%. A more even arrangement of reinforcing elements in the ground (close vertical and horizontal spacing between them Sh ≈ Sv
) ensures the maximum bearing capacity of a reinforced soil structure.
Technology of water supply to water inlets of pumping stations
Authors: Ergashev Rustam , Ismoilov Naim , Nasirova Naira , Kholbutaev Boybek , Khusanbayeva Khusnora , Nazarov Odil
Published: January 2021

The aim of the research is to increase the efficiency of pumping stations operation by improving the methods of uniform spreading of the flow from the front chamber and the water intake of the pumping station and the development of constructive measures to improve the hydraulic conditions of the flow supply to the pumps. This goal is achieved by the fact that the device for supplying water to the water intake contains guiding elements. The improvement of the method of hydraulic calculation of the flow in the front chamber and the water intake chamber is carried out on the example of the head pumping station of the Jizzakh cascade. In the process of research, standard methods of full-scale and bench tests of pumps, methods of mathematical and hydraulic modeling, statistical processing of results and the creation of mathematical models based on the laws of hydromechanics were used.

The project substantiates the choice of a technical solution to improve the hydraulic structure of the flow in front of the impeller of the pumps of the Jizzakh head pumping station. The authors have developed new technical solutions, including an element for influencing the flow, installed in the water intake chamber of the pumps. This makes it possible to expand the ranges of stable, cavitation-free operation of the pump, to ensure an increase in the reliability of water supply to the pumping station, without resorting to complex and expensive reconstruction measures.
The quality of loosening the soil with subsoilers of the combined machine
Authors: Fayzullayev Kh , Mamatov S , Radjabov M , Sharipov Sh , Tavashov R , Nurmanova M
Published: January 2021

The aim of the study is to study the influence of the parameters of subs oilers on the quality of loosening of the soil when preparing the soil for sowing melons and gourds under a film with a combined machine. The authors have developed a combined machine for preparing the soil for sowing melons and gourds under a film. The structural diagram of the developed machine is presented. Theoretically, the completeness of loosening of the soil by subs oilers of the machine is determined from their parameters and relative position. Theoretical and experimental studies have established that the scheme of pair wise arrangement of subs oilers inclined to the right and left of the combined machine with working surfaces facing each other, as well as shifted relative to each other in the longitudinal plane, provides the required quality of work, while the longitudinal distance between the subs oilers should be 75 cm, and the transverse distance is 60 cm.
Cotton harvesters for one-time cotton-picking
Authors: Rizaev Anvar , Matchanov Rafik , Yuldashev A T , Kuldashev D A , Djuraeva N B , Karimov Nuriddin , Ashurov Nurali
Published: January 2021

The paper provides the study and substantiation of the parameters of semi-hitched spindle cotton harvesters during one-time cotton-picking. A calculation scheme for the spindle interaction with an open cotton boll in the “cylinder-deformable ball” form was proposed. A mathematical model to change the distance between oppositely located spindle drums in the working chamber and a method to calculate the indentation of the boll contact on the spindle of a vertical-spindle picking apparatus were obtained. The model made it possible to calculate the rational technological parameters of the device and machine. Kinematic functioning parameters of vertical-and horizontal-spindle picking devices were specified, taking into account their installation on a semi-hitched cotton harvester. The obtained data were used to create machines for a one-time cotton-picking.
Bench-scale study of centrifugal fan parameters
Authors: Rizaev Anvar , Malikov Zafar , Yuldashev Abdurakhim , Kuldoshev Davronbek , Temirov Djamaliddin , Borotov Atkham
Published: January 2021

The article is devoted to the development of a special simulation bench installation for studying the quality of the centrifugal fan used in the suction -blower pneumatic transport system of modern vertical -spindle cotton pickers. The principle of operation of a production structure of a pneumatic transport system with a lateral elliptical inlet of the fan casing is described based on a known technical solution. In order to determine the optimal location of the lateral elliptical suction channel of the fan casing, a stand was created that includes a centrifugal fan mounted on a frame and receiving movement by means of a belt drive from an electric motor. Four different positions of the ellipsoidal inlet and one central side connection of the air intake to the fan casing were tested on the bench. Based on the experiments carried out using a given amount of transported cotton, the performance of the fan was determined with the least damage to the seeds.
Synthesis of submicron-sized carbon-doped TiO2 for photodegradation of formaldehyde from wood-based panels
Authors: Luo Ligang , Yao Weihui , Yuan Ronghui , Shi Wei , Jin Xiaohong , Hu Jianhua , Jiang Guojun
Published: January 2021

Carbon-doped TiO2 particles were prepared by hydrothermal treatments and characterised via field emission scanning electron microscopy, powder X-ray diffraction and X-ray photoelectron spectroscopy. The results show that carbon was successfully doped into the TiO2 structures. Photocatalytic reactions were further investigated in a simulated indoor environment, and the visible-light catalytic activity of the carbon-doped TiO2 was evaluated by monitoring the photodegradation of the formaldehyde from wood-based panels. A degradation rate of 90% in 70 min was obtained, which demonstrated high photocatalytic performance.
Ceramic proppants for hydraulic fracturing
Authors: Biryukova A A , Dzhienalyev T D , Panichkin A V
Published: January 2021

The purpose of the work is the development of ceramic proppants from serpentinites and red mud. The chemical and mineralogical composition of the raw material was studied. It has been established that the main mineral of serpentinites is serpentine, which is present in the form of fibrous chrysotile and lamellar antigorite. Red mud is represented by sodium aluminosilicates of various hydrated forms, silicon oxide and hematite. Structural-phase transformations of compositions based on serpentinite and red mud were studied in the heat treatment process. The proppant phase composition is represented by forsterite, clinoenstatite, spinel compounds and complex sodium aluminosilicates. Proppants of magnesia-silicate composition based on serpentinite and red mud have been obtained with the following properties: bulk density 1.59-1.61 g/cm3, fraction of crushed granules with a compressive load of 69 MPa no more than 22%, sphericity and roundness - 0.8, chemical resistance - 98%.
Research on the wear and life of copper tungsten alloy contacts of high voltage SF6 circuit breakers
Authors: Xu Chao , Huang Hai , Wang Ying , Shi Xingcai
Published: January 2021

Three phase short circuit and two phase short circuit grounding fault of power system have a significant influence on the electrical life of circuit breaker contact. In this paper, the mathematical model of each component is established by Power System Analysis Software Package (PSASP), and the simulation model is built to simulate the dynamic state of the circuit breaker after different short-circuit faults. The simulated result confirms that contact electrical wear quantity related to the type of short circuit fault and the position of short circuit point. The size of short circuit current will directly impact electrical wear quantity and electrical life of circuit breaker contact.
Synthesis and crystal structure of the one-dimensional chain triphenyltin compound bridged by 5-chloro-6-hydroxynicotinic acid
Authors: Gao Zhongjun , Zhang Haifeng , Sha Jingquan
Published: January 2021

Reaction of 5-chloro-6-hydroxynicotinic acid with Ph3SnCl and sodium ethoxide in 1:1:1 stoichiometry yielded triphenyltin compound. This compound has been characterized by single crystal X-ray diffraction, elemental analysis, IR and 1H NMR spectroscopy. In the molecular structure of the title compound, the tin atoms are five-coordinated in a distorted trigonal bipyramidal geometry. The resulting structure is 1D linear polymer through an interaction between the O atoms of phenolic hydroxide and tin atoms of an adjacent molcule. The compound exhibit high antitumor activity.
Microstructure and mechanical properties of Mg-2Sn-1.95Ca-0.5Ce alloy with different extrusion speeds
Authors: Wu Jianxun , Shu Hong , Zhang Maochao , Chen Yungui
Published: January 2021

Effects of extrusion speeds (0.3, 1.2, 1.8 and 3.5 mm s−1) on the microstructure and mechanical properties of the Mg–2Sn–1.95Ca–0.5Ce (TXCe220) alloy were analyzed by various detection methods in this article. The results have revealed that extrusion speed exerts a prominent influence towards grain size, recrystallization fraction and texture. As the extrusion speed increases, the microstructure characteristics transform from bimodal grain morphology to the near complete dynamical recrystallization (DRX). The tensile yield strength of TXCe220 decreased from 365 MPa to 180 MPa accompanied by the elongation increasing from 4.0 % to 19.4 % when the ram speed rises from 0.3 mm s−1 to 3.5 mm/s. The high yield strength of low-speed extruded alloys should be mainly ascribed to the nano-scale Mg2Ca with diameter of 30–80 nm precipitates, fine DRX grains and strong texture.
Ising spin configurations with the deep learning method
Authors: Zhang Yihang
Published: January 2021

In this work, we explore the statistical system's configuration generation with generative models from Deep Learning to go beyond conventional Monte Carlo methods. Specifically, we devise a conditional generative adversarial network (cGAN) for the Ising system spin configuration generation, and we demonstrate it's working outside the training range of temperature for the ensemble of configurations. Being different from the original GAN design, we add a further recognizer network for the constraint on the conditional parameters (in our case temperature) and also provide a diversity benefit for the generative model. We showed that the newly proposed cGAN here can learn the distribution of the Ising model for different temperatures, which can generate spin configuration efficiently with correct (within a probability distribution) temperature estimation for the microscopic configurations. Moreover, without information about criticality provided inside the training data set, it is also shown that the developed cGAN can generate Ising spin configurations around the phase transition point with the order parameter (mean magnetization) reasonably well-match to the conventional MCMC simulation but with parallel sampling advantage. We also compared typical spin configurations from cGAN with specified conditional temperature to be the critical temperature with samples simulated by MCMC, which visibly is not distinguishable. This thus can possibly help to avoid critical slowing-down as shown in the traditional Monte Carlo method.
Progress and prospects of thermo-mechanical energy storage—a critical review
Authors: Olympios Andreas V , McTigue Joshua D , Farres-Antunez Pau , Tafone Alessio , Romagnoli Alessandro , Li Yongliang , Ding Yulong , Steinmann Wolf-Dieter , Wang Liang , Chen Haisheng , Markides Christos N
Published: January 2021

The share of electricity generated by intermittent renewable energy sources is increasing (now at 26% of global electricity generation) and the requirements of affordable, reliable and secure energy supply designate grid-scale storage as an imperative component of most energy transition pathways. The most widely deployed bulk energy storage solution is pumped-hydro energy storage (PHES), however, this technology is geographically constrained. Alternatively, flow batteries are location independent and have higher energy densities than PHES, but remain associated with high costs and short lifetimes, which highlights the importance of developing and utilizing additional larger-scale, longer-duration and long-lifetime energy storage alternatives. In this paper, we review a class of promising bulk energy storage technologies based on thermo-mechanical principles, which includes: compressed-air energy storage, liquid-air energy storage and pumped-thermal electricity storage. The thermodynamic principles upon which these thermo-mechanical energy storage (TMES) technologies are based are discussed and a synopsis of recent progress in their development is presented, assessing their ability to provide reliable and cost-effective solutions. The current performance and future prospects of TMES systems are examined within a unified framework and a thermo-economic analysis is conducted to explore their competitiveness relative to each other as well as when compared to PHES and battery systems. This includes carefully selected thermodynamic and economic methodologies for estimating the component costs of each configuration in order to provide a detailed and fair comparison at various system sizes. The analysis reveals that the technical and economic characteristics of TMES systems are such that, especially at higher discharge power ratings and longer discharge durations, they can offer promising performance (round-trip efficiencies higher than 60%) along with long lifetimes (>30 years), low specific costs (often below 100 $ kWh−1), low ecological footprints and unique sector-coupling features compared to other storage options. TMES systems have significant potential for further progress and the thermo-economic comparisons in this paper can be used as a benchmark for their future evolution.
Monochromatic image reconstruction via machine learning
Authors: Cong Wenxiang , Xi Yan , De Man Bruno , Wang Ge
Published: January 2021

X-ray computed tomography (CT) is a nondestructive imaging technique to reconstruct cross-sectional images of an object using x-ray measurements taken from different view angles for medical diagnosis, therapeutic planning, security screening, and other applications. In clinical practice, the x-ray tube emits polychromatic x-rays, and the x-ray detector array operates in the energy-integrating mode to acquire energy intensity. This physical process of x-ray imaging is accurately described by an energy-dependent non-linear integral equation on the basis of the Beer–Lambert law. However, the non-linear model is not invertible using a computationally efficient solution and is often approximated as a linear integral model in the form of the Radon transform, which basically loses energy-dependent information. This approximate model produces an inaccurate quantification of attenuation images, suffering from beam-hardening effects. In this paper, a machine learning-based approach is proposed to correct the model mismatch to achieve quantitative CT imaging. Specifically, a one-dimensional network model is proposed to learn a non-linear transform from a training dataset to map a polychromatic CT image to its monochromatic sinogram at a pre-specified energy level, realizing virtual monochromatic (VM) imaging effectively and efficiently. Our results show that the proposed method recovers high-quality monochromatic projections with an average relative error of less than 2%. The resultant x-ray VM imaging can be applied for beam-hardening correction, material differentiation and tissue characterization, and proton therapy treatment planning.
The Association of the Parent–Child Language Acculturation Gap with Obesity and Cardiometabolic Risk in Hispanic/Latino Youth: Results from the Hispanic Community Children’s Health Study/Study of Latino Youth (SOL Youth)
Authors: LeCroy Madison N , Strizich Garrett M , Gallo Linda C , Perreira Krista P , Ayala Guadalupe X , Carnethon Mercedes R , Delamater Alan M , Gonzalez Jeffrey S , Arredondo Elva M , Pulgaron Elizabeth R , Isasi Carmen R
Published: January 2021

Background

Hispanic/Latino youth are disproportionately burdened by obesity and have a high prevalence of prediabetes and dyslipidemia. Differences in parent and child acculturation related to language use and preference (i.e., language acculturation) are associated with adverse cardiometabolic health behaviors, but no study has examined associations with cardiometabolic markers.

Purpose

To determine whether discordance in parent–child language acculturation (parent–child acculturation gap) was associated with poor youth cardiometabolic health.

Methods

Hispanic/Latino 8–16-year-olds (n = 1,466) and parents from the Hispanic Community Children’s Health Study/Study of Latino Youth (SOL Youth) were examined. Mean scores for the Brief ARSMA-II’s Anglo (AOS) and Latino (LOS) Orientation Scales represented language acculturation. Cardiometabolic markers included youth body mass index (BMI) percentile, blood pressure percentiles, and dysglycemia and hyperlipidemia measures. Missing data were imputed. Survey-weighted multivariable linear regression examined the association of youth, parent, and youth × parent (the acculturation gap) AOS and LOS scores separately with each cardiometabolic marker.

Results

Youth reported greater English and lower Spanish use than parents. Greater discordance in AOS scores was associated with elevated BMI percentile only (p-for-interaction < .01). The LOS acculturation gap was not associated with any outcome. Adjustment for acculturative stress, family functioning and closeness, parenting style, and youth’s diet and physical activity did not alter findings. Removal of nonsignificant acculturation gaps did not indicate an association between individual youth or parent AOS or LOS scores and any cardiometabolic marker.

Conclusions

Discordance in Hispanic/Latino parent–child dyads’ English use may relate to increased risk for childhood obesity. Future studies should identify mediators of this association.
Exploring the Role of Supplemental Foods for Improved Greenhouse Biological Control
Authors: Benson Carly M , Labbe Roselyne M
Published: January 2021

Small modifications in greenhouse agroenvironments can have a big impact on the success of biological control programs. For instance, the application of supplemental foods during and after the release of natural enemies onto crop plants, could considerably improve their long-term reproductive and population growth prospects. As such, food supplementation represents a valuable biological control supportive strategy, helping to grow natural enemy populations before pest establishment, akin to creating a standing-army to defend crops against future pest invasions. In many places of the world, food supplementation represents a relatively new but growing component or biological control research, with increasingly better resources available to guide producers, IPM practitioners, or researchers wanting to apply or optimize such strategies to their local agents and environments. In this review, we summarize the current stage of knowledge associated with various supplemental food types, which work best to support specific beneficial arthropods as well as some tools and techniques for successfully applying this biological control-enhancing strategy. We also summarize some current challenges to the use of supplemental foods and discuss what future research is needed to adapt and optimize food supplementation for a diversity of natural enemy species.
Comprehensive benchmarking of software for mapping whole genome bisulfite data: from read alignment to DNA methylation analysis
Authors: Nunn Adam , Otto Christian , Stadler Peter F , Langenberger David
Published: January 2021

Whole genome bisulfite sequencing is currently at the forefront of epigenetic analysis, facilitating the nucleotide-level resolution of 5-methylcytosine (5mC) on a genome-wide scale. Specialized software have been developed to accommodate the unique difficulties in aligning such sequencing reads to a given reference, building on the knowledge acquired from model organisms such as human, or Arabidopsis thaliana. As the field of epigenetics expands its purview to non-model plant species, new challenges arise which bring into question the suitability of previously established tools. Herein, nine short-read aligners are evaluated: Bismark, BS-Seeker2, BSMAP, BWA-meth, ERNE-BS5, GEM3, GSNAP, Last and segemehl. Precision-recall of simulated alignments, in comparison to real sequencing data obtained from three natural accessions, reveals on-balance that BWA-meth and BSMAP are able to make the best use of the data during mapping. The influence of difficult-to-map regions, characterized by deviations in sequencing depth over repeat annotations, is evaluated in terms of the mean absolute deviation of the resulting methylation calls in comparison to a realistic methylome. Downstream methylation analysis is responsive to the handling of multi-mapping reads relative to mapping quality (MAPQ), and potentially susceptible to bias arising from the increased sequence complexity of densely methylated reads.
Post-thyroidectomy bleeding: analysis of risk factors from a national registry
Authors: Doran H E , Wiseman S M , Palazzo F F , Chadwick D , Aspinall S
Published: January 2021

Background

Post-thyroidectomy haemorrhage occurs in 1–2 per cent of patients, one-quarter requiring bedside clot evacuation. Owing to the risk of life-threatening haemorrhage, previous British Association of Endocrine and Thyroid Surgeons (BAETS) guidance has been that day-case thyroidectomy could not be endorsed. This study aimed to review the best currently available UK data to evaluate a recent change in this recommendation.

Methods

The UK Registry of Endocrine and Thyroid Surgery was analysed to determine the incidence of and risk factors for post-thyroidectomy haemorrhage from 2004 to 2018.

Results

Reoperation for bleeding occurred in 1.2 per cent (449 of 39 014) of all thyroidectomies. In multivariable analysis male sex, increasing age, redo surgery, retrosternal goitre and total thyroidectomy were significantly correlated with an increased risk of reoperation for bleeding, and surgeon monthly thyroidectomy rate correlated with a decreased risk. Estimation of variation in bleeding risk from these predictors gave low pseudo-R2 values, suggesting that bleeding is unpredictable. Reoperation for bleeding occurred in 0.9 per cent (217 of 24 700) of hemithyroidectomies, with male sex, increasing age, decreasing surgeon volume and redo surgery being risk factors. The mortality rate following thyroidectomy was 0.1 per cent (23 of 38 740). In a multivariable model including reoperation for bleeding node dissection and age were significant risk factors for mortality.

Conclusion

The highest risk for bleeding occurred following total thyroidectomy in men, but overall bleeding was unpredictable. In hemithyroidectomy increasing surgeon thyroidectomy volume reduces bleeding risk. This analysis supports the revised BAETS recommendation to restrict day-case thyroid surgery to hemithyroidectomy performed by high-volume surgeons, with caution in the elderly, men, patients with retrosternal goitres, and those undergoing redo surgery.
Prosthetic Valve Endocarditis Diagnosis and Management— New Paradigm Shift Narratives
Authors: Bayer Arnold S , Chambers Henry F
Published: January 2021

Prosthetic valve endocarditis (PVE) is a major infectious disease problem due to the increasing numbers of patients undergoing valve replacement surgery. PVE can present diagnostic difficulties echocardiographically, especially when complicating transvascular placement techniques. Moreover, outbreaks of unusual PVE pathogens, such as Mycobacterium chimaera, have presented major diagnostic and therapeutic dilemmas.
Surgery is an option in evolving myocardial infarction induced by spontaneous coronary artery dissection: a case report
Authors: Al Mahruqi Ghaitha , Alsabti Hilal , Mukaddirov Mirdavron
Published: January 2021

Background

Spontaneous coronary artery dissection (SCAD) has emerged as one of the important yet rare causes of acute coronary syndrome that primarily affect young peripartum women without cardiovascular risk factors. Despite the recent improvements in diagnosis and recognition of the importance of SCAD, it remains poorly studied and there has been no consensus of opinion regarding its optimal management.

Case summary

A 29-year-old breastfeeding woman presented with 1-day history of severe chest pain radiating to the jaw and both shoulders. Cardiovascular examination, 12 leads electrocardiogram, and echocardiography were normal. Troponin levels were elevated; hence, coronary angiogram was done and showed type 2 SCAD of the left anterior descending artery (LAD). The patient was managed conservatively. The next day, she started again to complain of severe chest pain and her troponin levels continued to rise. Repeated coronary angiogram revealed progression of the previous LAD dissection. Another dissection was also noticed in the left circumflex artery. Chest pain recurred over the night and her troponin levels continued to rise. An emergency coronary artery bypass grafting (CABG) was performed. The patient was doing well postoperatively and was discharged home on Day 8.

Discussion

Our patient presented with acute ischaemic changes secondary to SCAD. The report illustrates the risk factors, pathogenesis, diagnostic work up, and the possible therapeutic options of SCAD, which include conservative management and CABG. The management varies depending on the clinical presentation and the extent of the coronary artery dissection.
Use of extracorporeal membrane oxygenation as a bridge to transcatheter aortic valve replacement in a patient with aortic stenosis and severe coronary artery disease: a case report
Authors: Ahsan Majid , Jánosi Rolf Alexander , Rassaf Tienush , Lind Alexander
Published: January 2021

Background

Patients with severe aortic stenosis (AS) often present with multiple comorbidities and suffer from critical coronary artery disease (CAD). Transcatheter aortic valve replacement (TAVR) has become the therapy of choice for moderate to high-risk patients. Venoarterial extracorporeal membrane oxygenation (v-a-ECMO) offers the possibility of temporary cardiac support to manage life-threatening critical situations.

Case summary

Here, we describe the management of a patient with severe AS and CAD with impaired left ventricular ejection fraction (LVEF). We used v-a-ECMO as an emergency strategy in cardiogenic shock during a high-risk coronary intervention to stabilize the patient, and as a further bridge to TAVR.

Discussion

Very high-risk patients with severe AS are unlikely to tolerate the added risk of surgical aortic valve replacement. Using ECMO may help them to benefit from TAVR as the only treatment option available.
Is open window thoracostomy the only method to control infection in patients with an empyema following pulmonary resection for primary lung cancer?
Authors: Wotton Robin , Garner Megan , Salem Agni , Buderi Silviu
Published: January 2021

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed: Is open window thoracostomy (OWT) the only method to control infection in patients with an empyema following pulmonary resection for primary lung cancer? Altogether 442 papers were found using the reported search, of which 9 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Empyema following anatomical lung resection (excluding pneumonectomy) is an uncommon complication but one that remains a challenge to treat effectively. Chest tube thoracostomy and intravenous antibiotics remain the initial steps to management, but evidence is lacking with regard to the best ongoing strategy. Conservative options including chest cavity irrigation, postural drainage and vacuum-assisted closure have been attempted with some success, even in the presence of a broncho-pleural fistula. However, the very limited number of patients on which these various management strategies have been trialled on prevents recommendations and clear guidance being given.
Performance assessment of solar chimney power plants with the impacts of divergent and convergent chimney geometry
Authors: Cuce Erdem , Saxena Abhishek , Cuce Pinar Mert , Sen Harun , Guo Shaopeng , Sudhakar K
Published: January 2021

Influence of area ratio (AR) on main performance parameters of solar chimney power plants (SCPPs) is investigated through a justified 3D axisymmetric CFD model. Geometric characteristics of Manzanares pilot plant (MPP) are taken into consideration for the numerical model. AR is varied from 0.5 to 10 to cover both concave and convex (convergent and divergent) solar chimney designs. Following the accuracy verification of the CFD results and proving mesh-independent solution, main performance oriented parameters are assessed as a function of AR such as velocity, temperature and pressure distribution within MPP, temperature rise of air in collector, mass flow rate of air around the turbine area, dynamic pressure difference across the turbine, minimum static pressure in the entire plant, power output and system efficiency. The results reveal that AR plays a vital role in performance figures of MPP. Mass flow rate of air ($\dot{m}$) is found to be 1122.1 kg/s for the reference geometry (AR = 1), whereas it is 1629.1 kg/s for the optimum AR value of 4. System efficiency (η) is determined to be 0.29% for the reference case; however, it is enhanced to 0.83% for the AR of 4.1. MPP can generate 54.3 kW electrical power in its current design while it is possible to improve this figure to 168.5 kW with the optimal AR value.
Encompassing Tests for Value at Risk and Expected Shortfall Multistep Forecasts Based on Inference on the Boundary
Authors: Dimitriadis Timo , Liu Xiaochun , Schnaitmann Julie
Published: January 2021

We propose forecast encompassing tests for the expected shortfall (ES) jointly with the value at risk (VaR) based on flexible link (or combination) functions. Our setup allows testing encompassing for convex forecast combinations and for link functions that preclude crossings of the combined VaR and ES forecasts. As the tests based on these link functions involve parameters that are on the boundary of the parameter space under the null hypothesis, we derive and base our tests on nonstandard asymptotic theory on the boundary. Our simulation study shows that the encompassing tests based on our new link functions outperform tests based on unrestricted linear link functions for one-step and multistep forecasts. We further illustrate the potential of the proposed tests in a real data analysis for forecasting VaR and ES of the S&P 500 index.
Media Attention and Bureaucratic Responsiveness
Authors: Erlich Aaron , Berliner Daniel , Palmer-Rubin Brian , Bagozzi Benjamin E
Published: January 2021

How does media attention shape bureaucratic behavior? We answer this question using novel data from the Mexican federal government. We first develop a new indicator for periods of anomalously heightened media attention, based on 150,000 news articles pertaining to 22 Mexican government ministries and agencies, and qualitatively categorize their themes. We then evaluate government responsiveness using administrative data on roughly 500,000 requests for government information over a 10-year period, with their associated responses. A panel fixed-effects approach demonstrates effects of media attention on the volume of outgoing weekly responses, while a second approach finds effects on the “queue” of information requests already filed when anomalous media attention begins. Consistent across these empirical approaches, we find that media attention shapes bureaucratic behavior. Positive or neutral attention is associated with reduced responsiveness, while the effects of negative attention vary, with attention to government failures leading to increased responsiveness but attention to corruption leading to reduced responsiveness. These patterns are consistent with mechanisms of reputation management, disclosure threat, and workload burden, but inconsistent with mechanisms of credit claiming or blame avoidance.
Contingent Homes: Mobility and Long-Term Conflict in the Contested Periphery of Georgia
Authors: Aydemir Görkem
Published: January 2021

Displaced Georgians in the de facto Georgia-Abkhazia borderland have lived in a zone of protracted ambivalence and contingency for almost three decades. During the war between the post-Socialist Georgian state and Abkhaz forces supporting the independence of Abkhazia, Georgian residents of Abkhazia were forced to flee to Georgia proper. Soon after the war’s end, thousands of displaced people started to access their homes in Gali, the southern borderland of the de facto state of Abkhazia. By persistently navigating shifting places and sovereignties, displaced Georgians from Gali construct lives on the move in a disputed and militarized borderland where contingency, surveillance, and economic precarity infiltrate everyday life. In such a space of life projects grounded in contested mobilities, home emerges as a question of being able to move across a disputed border rather than returning to a singular and fixed place.
Introduction to Special Issue: Displaced Syrians
Authors: Chatty Dawn
Published: January 2021

The articles presented here in this special issue on Displaced Syria emerged from a workshop held at The Institute of New York University in Abu Dhabi in March 2019. Its aims were to encourage an examination of the perceptions and aspiration of displaced Syrians and practitioners in hosting countries in the Levant, the Gulf, and in Europe with special attention to the voices of the displaced, their reimagining of home and homeland, and the emerging transnational sense of identity and belonging.
Priapism for 10 days in a patient with SARS-CoV-2 pneumonia: a case report
Authors: Addar Abdulmalik , Al Fraidi Omar , Nazer Ahmed , Althonayan Naif , Ghazwani Yahya
Published: January 2021

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been linked to thromboembolic complications. Priapism has been reported only once in link to SARS-CoV2.

Here we report the second case of priapism in a patient with SARS-CoV2; our case is unique in being that the patient had priapism for 10 days while being hospitalized. We discuss potential causes and possible prevention strategies. The patient was managed by aspiration and Phenylephrine injection and achieved detumescence and reported normal erection at 2 weeks follow-up.
Planetary embryo collisions and the wiggly nature of extreme debris discs
Authors: Watt Lewis , Leinhardt Zoe , Su Kate Y L
Published: January 2021

In this paper, we present results from a multistage numerical campaign to begin to explain and determine why extreme debris disc detections are rare, what types of impacts will result in extreme debris discs and what we can learn about the parameters of the collision from the extreme debris discs. We begin by simulating many giant impacts using a smoothed particle hydrodynamical code with tabulated equations of state and track the escaping vapour from the collision. Using an N-body code, we simulate the spatial evolution of the vapour generated dust post-impact. We show that impacts release vapour anisotropically not isotropically as has been assumed previously and that the distribution of the resulting generated dust is dependent on the mass ratio and impact angle of the collision. In addition, we show that the anisotropic distribution of post-collision dust can cause the formation or lack of formation of the short-term variation in flux depending on the orientation of the collision with respect to the orbit around the central star. Finally, our results suggest that there is a narrow region of semimajor axis where a vapour generated disc would be observable for any significant amount of time implying that giant impacts where most of the escaping mass is in vapour would not be observed often but this does not mean that the collisions are not occurring.
Rotating vector model for magnetars
Authors: Tong H , Wang P F , Wang H G , Yan Z
Published: January 2021

The modification of the rotating vector model in the case of magnetars are calculated. Magnetars may have twisted magnetic field compared with normal pulsars. The polarization position angle of magnetars will change in the case of a twisted magnetic field. For a twisted dipole field, we found that the position angle will change both vertically and horizontally. During the untwisting process of the magnetar magnetosphere, the modifications of the position angle will evolve with time monotonously. This may explain the evolution of the position angle in magnetar PSR J1622-4950 and XTE J1810-197. The relation between the emission point and the line of sight will also change. We suggest every magnetospheric models of magnetars also calculate the corresponding changes of position angle in their models. Order of magnitude estimation formula for doing this is given. This opens the possibility to extract the magnetic field geometry of magnetars from their radio polarization observations.
Test of the cosmic distance duality relation for arbitrary spatial curvature
Authors: Qin Jin , Melia Fulvio , Zhang Tong-Jie
Published: January 2021

The cosmic distance duality relation (CDDR), η(z) = (1 + z)2dA(z)/dL(z) = 1, is one of the most fundamental and crucial formulae in cosmology. This relation couples the luminosity and angular diameter distances, two of the most often used measures of structure in the Universe. We here propose a new model-independent method to test this relation, using strong gravitational lensing (SGL) and the high-redshift quasar Hubble diagram reconstructed with a Bézier parametric fit. We carry out this test without pre-assuming a zero spatial curvature, adopting instead the value ΩK = 0.001 ± 0.002 optimized by Planck in order to improve the reliability of our result. We parametrize the CDDR using η(z) = 1 + η0z, 1 + η1z + η2z2, and 1 + η3z/(1 + z), and consider both the SIS and non-SIS lens models for the strong lensing. Our best-fitting results are: $\eta _0=-0.021^{+0.068}_{-0.048}$, $\eta _1=-0.404^{+0.123}_{-0.090}$, $\eta _2=0.106^{+0.028}_{-0.034}$, and $\eta _3=-0.507^{+0.193}_{-0.133}$ for the SIS model, and $\eta _0=-0.109^{+0.044}_{-0.031}$ for the non-SIS model. The measured η(z), based on the Planck parameter ΩK, is essentially consistent with the value (=1) expected if the CDDR were fully respected. For the sake of comparison, we also carry out the test for other values of ΩK, but find that deviations of spatial flatness beyond the Planck optimization are in even greater tension with the CDDR. Future measurements of SGL may improve the statistics and alter this result but, as of now, we conclude that the CDDR favours a flat Universe.
SPIDERS: an overview of the largest catalogue of spectroscopically confirmed x-ray galaxy clusters
Authors: Kirkpatrick C C , Clerc N , Finoguenov A , Damsted S , Ider Chitham J , Kukkola A E , Gueguen A , Furnell K , Rykoff E , Comparat J , Saro A , Capasso R , Padilla N , Erfanianfar G , Mamon G A , Collins C , Merloni A , Brownstein J R , Schneider D P
Published: January 2021

SPIDERS is the spectroscopic follow-up effort of the Sloan Digital Sky Survey IV (SDSS-IV) project for the identification of X-ray selected galaxy clusters. We present our catalogue of 2740 visually inspected galaxy clusters as part of the SDSS Data Release 16 (DR16). Here we detail the target selection, our methods for validation of the candidate clusters, performance of the survey, the construction of the final sample, and a full description of what is found in the catalogue. Of the sample, the median number of members per cluster is approximately 10, with 818 having 15 or greater. We find that we are capable of validating over 99 per cent of clusters when five redshifts are obtained below z < 0.3 and when nine redshifts are obtained above z > 0.3. We discuss the improvements in this catalogue’s identification of cluster using 33 340 redshifts, with Δzphot/Δzspec ∼ 100, over other photometric and spectroscopic surveys, as well as presenting an update to previous (σ–LX) and (σ–λ) relations. Finally, we present our cosmological constraints derived using the velocity dispersion function.