bluuebunny/crossref_metadata_2025 huggingface dataset:
Time-Adaptive Determination of Drug Efficacy in Mathematical Model of HIV Infection
Authors: Beilina L. , Eriksson M. , Gainova I.
Published: June 2021

The paper considers a time-adaptive finite element method for determination of drug efficacy in a parameter identification problem (PIP) for a system of ordinary differential equations (ODE) that describes dynamics of the primary human immunodeficiency virus (HIV) infection with drug therapy. Tikhonov’s regularization method, optimization approach and finite element method to solve this problem are presented. A posteriori error estimates in the Tikhonov’s functional and reconstructed parameter are derived. Based on these estimates a time adaptive algorithm is formulated and numerically tested for different scenarios of noisy observations of virus population function. Numerical results show a significant improvement of reconstruction of drug efficacy parameter using the local time-adaptive mesh refinement method compared to the gradient method applied on a uniform time mesh.
Epistemic values of quantity and variety of evidence in biological mechanism research
Authors: Au Yin Chung
Published: June 2021

This paper proposes an extended version of the interventionist account for causal inference in the practical context of biological mechanism research. This paper studies the details of biological mechanism researchers’ practices of assessing the evidential legitimacy of experimental data, arguing why quantity and variety are two important criteria for this assessment. Because of the nature of biological mechanism research, the epistemic values of these two criteria result from the independence both between the causation of data generation and the causation in question and between different interventions, not techniques. The former independence ensures that the interventions in the causation in question are not affected by the causation that is responsible for data generation. The latter independence ensures the reliability of the final mechanisms not only in the empirical but also the formal aspects. This paper first explores how the researchers use quantity to check the effectiveness of interventions, where they at the same time determine the validity of the difference-making revealed by the results of interventions. Then, this paper draws a distinction between experimental interventions and experimental techniques, so that the reliability of mechanisms, as supported by the variety of evidence, can be safely ensured in the probabilistic sense. The latter process is where the researchers establish evidence of the mechanisms connecting the events of interest. By using case studies, this paper proposes to use ‘intervention’ as the fruitful connecting point of literature between evidence and mechanisms.
An overall performance index for wind farms: a case study in Norway Arctic region
Authors: Mustafa Albara M. , Barabadi Abbas , Markeset Tore , Naseri Masoud
Published: June 2021

Wind farms (WFs) experience various challenges that affect their performance. Mostly, designers focus on the technical side of WFs performance, mainly increasing the power production of WFs, through improving their manufacturing and design quality, wind turbines capacity, their availability, reliability, maintainability, and supportability. On the other hand, WFs induce impacts on their surroundings, these impacts can be classified as environmental, social, and economic, and can be described as the sustainability performance of WFs. A comprehensive tool that combines both sides of performance, i.e. the technical and the sustainability performance, is useful to indicate the overall performance of WFs. An overall performance index (OPI) can help operators and stakeholders rate the performance of WFs, more comprehensively and locate the weaknesses in their performance. The performance model for WFs, proposed in this study, arranges a set of technical and sustainability performance indicators in a hierarchical structure. Due to lack of historical data in certain regions where WFs are located, such as the Arctic, expert judgement technique is used to determine the relative weight of each performance indicator. In addition, scoring criteria are predefined qualitatively for each performance indicator. The weighted sum method makes use of the relative weights and the predefined scoring criteria to calculate the OPI of a specific WF. The application of the tool is illustrated by a case study of a WF located in the Norwegian Arctic. Moreover, the Arctic WF is compared to another WF located outside the Arctic to illustrate the effects of Arctic operating conditions on the OPI.
Synthesis of photocatalytic zinc oxide nanoflowers using Peltophorum pterocarpum pod extract and their characterization
Authors: Vinayagam Ramesh , Pai Shraddha , Murugesan Gokulakrishnan , Varadavenkatesan Thivaharan , Selvaraj Raja
Published: June 2021

Zinc oxide nanoflowers (ZnONFs) were prepared by employing the pod extract of Peltophorum pterocarpum as a green resource and characterized by various methods. UV–vis spectrum displayed a peak at 361 nm which confirmed the formation of ZnO nanoparticles. The optical band gap was calculated as 3.43 eV. FE-SEM images exposed the flower-like morphology and EDX portrayed strong signals for Zn and O. XRD studies substantiated signature peaks for the wurtzite phase of ZnONFs and the lattice parameters matched well with the literature. Mesoporous nature was confirmed by BET analysis which yielded a high specific surface area of 19.61 m2/g. FTIR bands at 420.48 and 462.92 cm−1affirmed the Zn and O bonding vibrations. The photocatalytic potential of the ZnONFs was successfully examined for the removal of methylene blue dye under natural solar light. The experimental data were fitted to Langmuir–Hinshelwood’s first-order equation and the kinetic constant was calculated as 0.0114 min–1.
Incentives, ability and disutility of effort
Authors: Martinez-Gorricho Silvia , Sanchez Villalba Miguel
Published: June 2021

We generalize the disutility of effort function in the linear-Constant Absolute Risk Aversion (CARA) pure moral hazard model. We assume that agents are heterogeneous in ability. Each agent’s ability is observable and treated as a parameter that indexes the disutility of effort associated with the task performed. In opposition to the literature (the “traditional” scenario), we find a new, “novel” scenario, in which a high-ability agent may be offered a weaker incentive contract than a low-ability one, but works harder. We characterize the conditions for the existence of these two scenarios: formally, the “traditional” (“novel”) scenario occurs if and only if the marginal rate of substitution of the marginal disutility of effort function is increasing (decreasing) in effort when evaluated at the second-best effort. If, further, this condition holds for all parameter values and matching is endogenous, less (more) talented agents work for principals with riskier projects in equilibrium. This implies that the indirect and total effects of risk on incentives are negative under monotone assortative matching.
Review of variable leading-edge patents for aircraft wings and engine inlets and their relevance for variable pitot inlets in future supersonic transport
Authors: Kazula S. , Höschler K.
Published: June 2021

The motivation for designing variable pitot inlets for future supersonic transport (SST) is explained. A comprehensive overview of existing technological solutions for variable leading edges of aircraft wings and engine inlets is given. The advantages and limitations of over 80 solutions, as well as their relevance for application on variable pitot inlets for SST are described. The challenges of existing solution options concerning design methodologies, level of detail, and experience with a technology are identified.
Ambient vibration testing and operational modal analysis of monopole telecoms structures
Authors: Jimenez Capilla Jose Alfonso , Au Siu-Kui , Brownjohn James Mark William , Hudson Emma
Published: June 2021

A structural health monitoring (SHM) system was developed to study the ambient response of monopole communication structures in the UK operated by Arqiva Ltd. The exercise had several purposes that included the evaluation of the SHM system itself and the system identification procedures applied to the data, followed by analysis of the evaluated modal properties to validate the current analytical models, structural assessments and standardised design procedures advising on dynamics actions. This paper describes the instrumentation and procedures used during monitoring of a lightweight flexible 14.5 m tubular tapered monopole supporting an array of mobile telecoms antennas. A Bayesian OMA (BAYOMA) approach is implemented to identify structural modal properties under different time windows as comparison for further assessments. Results from stochastic subspace identification are also obtained and compared. The correlation between modal properties and monitoring wind-response data reveals specific tendencies such as nonlinear stiffness behaviour, the existence of aerodynamic damping and typical directionality of the mode shapes with future implications for reformulation of current methods of assessing dynamics on monopole.
Inflammatory disease of the costotransverse joints: US evaluation in 15 symptomatic patients
Authors: Del Chiaro A. , Ciampi B. , Franzoni F. , Miccoli M. , Galletti S. , Stella S. M.
Published: June 2021

The costotransverse joints (CTJs) are small arthrodial joints which articulate with the costal tuberosity on the transverse process of the thoracic vertebrae. CTJs are composed of oval-shaped facets with a major axis, vertical at the upper vertebrae and almost horizontal at the lower vertebrae. This position explains the different movements of the ribs: the cranial ribs move on the sagittal plane and the caudal ribs on the transverse plane. Movements in directions other than these usual CTJ spatial planes can cause inflammation resulting in a stinging pain in the space between the scapula and thoracic spine. We studied 15 subjects with paravertebral pain compatible with CTJ pathology. Mean age was 29 years, 11 females/4 males. In 12 patients, the non-dominant limb was affected. US imaging was carried out using linear 12 MHz and 9 MHz probes. Scanning was performed following the long axis of the rib (transverse plane) and the short axis (sagittal plane). Sagittal scanning is the method of choice for detection of possible joint effusion and comparison with undamaged joints above and below. US identified joint effusion correlating with the site of pain in all patients. Thickening of the posterior costotransverse capsular ligament was detected in six patients mainly affecting the first thoracic vertebrae. Power Doppler showed intraarticular hypervascularization in four patients. US imaging should be performed as a first-line examination in the evaluation of patients with stinging pain in the paravertebral region. US evidence of effusion within the joints is a sure sign of involvement of these structures.
Appendicular skeletal muscle mass and quality estimated by bioelectrical impedance analysis in the assessment of frailty syndrome risk in older individuals
Authors: Kołodziej Małgorzata , Sebastjan Anna , Ignasiak Zofia
Published: June 2021

Background and aim

The rising aging index of many populations necessitates the continuous evolution of geriatric assessment methods, especially the ones used to identify frailty and the risk of frailty. An appropriately early diagnosis of adverse changes in skeletal muscles can reduce the risk of functional limitations in elderly persons. The aim of this study was to assess the correlation between the appendicular skeletal muscle mass and quality, estimated by the bioelectrical impedance analysis method, and the risk of prevalence of the pre-frailty state in elderly persons.

Methods

One-thousand-and-fifteen subjectively healthy persons aged 60–87 years were tested. Anthropometric measurements and physical fitness and activity measurements were carried out and the frailty phenotype was evaluated. Appendicular skeletal muscle mass was estimated using the bioelectrical impedance analysis method. Muscle quality was assessed through an index correcting strength relative to muscle mass and through the impedance phase angle. The correlation between the muscle mass and quality estimating parameters and the probability of identifying pre-frailty was checked using multiple logistic regression.

Results

The prevalence of pre-frailty was 38%. The pre-frail persons were found to have a significantly lower muscle mass and quality than the non-frail persons, with the difference in the case of the muscle quality index nearly twice larger than for the muscle mass index. A significant logit model was obtained for pre-frailty prevalence, which was strongly dependent on the appendicular skeletal muscle mass (adjusted odds ratio (OR): 0.43, 95% CI 0.36–0.52, p < 0.001) and functional quality (adjusted OR: 0.26, 95% CI 0.18–0.38, p < 0.001) and less on age (adjusted OR: 1.10, 95% CI 1.07–1.13, p < 0.001).

Conclusion

The strong correlation between the frailty phenotype and appendicular skeletal muscle mass and functional quality suggests that the two variables should be included in routine geriatric assessment with regard to frailty.
Vitamin D and coronavirus disease 2019 (COVID-19): rapid evidence review
Authors: Raisi-Estabragh Zahra , Martineau Adrian R. , Curtis Elizabeth M. , Moon Rebecca J. , Darling Andrea , Lanham-New Susan , Ward Kate A. , Cooper Cyrus , Munroe Patricia B. , Petersen Steffen E. , Harvey Nicholas C.
Published: June 2021

Background

The rapid global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19), has re-ignited interest in the possible role of vitamin D in modulation of host responses to respiratory pathogens. Indeed, vitamin D supplementation has been proposed as a potential preventative or therapeutic strategy. Recommendations for any intervention, particularly in the context of a potentially fatal pandemic infection, should be strictly based on clinically informed appraisal of the evidence base. In this narrative review, we examine current evidence relating to vitamin D and COVID-19 and consider the most appropriate practical recommendations.

Observations

Although there are a growing number of studies investigating the links between vitamin D and COVID-19, they are mostly small and observational with high risk of bias, residual confounding, and reverse causality. Extrapolation of molecular actions of 1,25(OH)2-vitamin D to an effect of increased 25(OH)-vitamin D as a result of vitamin D supplementation is generally unfounded, as is the automatic conclusion of causal mechanisms from observational studies linking low 25(OH)-vitamin D to incident disease. Efficacy is ideally demonstrated in the context of adequately powered randomised intervention studies, although such approaches may not always be feasible.

Conclusions

At present, evidence to support vitamin D supplementation for the prevention or treatment of COVID-19 is inconclusive. In the absence of any further compelling data, adherence to existing national guidance on vitamin D supplementation to prevent vitamin D deficiency, predicated principally on maintaining musculoskeletal health, appears appropriate.
Effects of testosterone treatment on clitoral haemodynamics in women with sexual dysfunction
Authors: Cipriani S. , Maseroli E. , Di Stasi V. , Scavello I. , Todisco T. , Rastrelli G. , Fambrini M. , Sorbi F. , Petraglia F. , Jannini E. A. , Maggi M. , Vignozzi L.
Published: June 2021

Purpose

To explore the effects of 6-month systemic testosterone (T) administration on clitoral color Doppler ultrasound (CDU) parameters in women with female sexual dysfunction (FSD).

Methods

81 women with FSD were retrospectively recruited. Data on CDU parameters at baseline and after 6 months with four different treatments were available and thus further longitudinally analyzed: local non-hormonal moisturizers (NH group), n = 37; transdermal 2% T gel 300 mcg/day (T group), n = 23; local estrogens (E group), n = 12; combined therapy (T + E group), n = 9. Patients underwent physical, laboratory, and genital CDU examinations at both visits and completed different validated questionnaires, including the Female Sexual Function Index (FSFI).

Results

At 6-month visit, T therapy significantly increased clitoral artery peak systolic velocity (PSV) when compared to both NH (p < 0.0001) and E (p < 0.0001) groups. A similar increase was found in the T + E group (p = 0.039 vs. E). In addition, T treatment was associated with significantly higher FSFI desire, pain, arousal, lubrication, orgasm, and total scores at 6-month visit vs. baseline. Similar findings were observed in the T + E group. No significant differences in the variations of total and high-density lipoprotein-cholesterol, triglycerides, fasting glycemia, insulin and glycated hemoglobin levels were found among the four groups. No adverse events were observed.

Conclusion

In women complaining for FSD, systemic T administration, either alone or combined with local estrogens, was associated with a positive effect on clitoral blood flow and a clinical improvement in sexual function, showing a good safety profile.

Trial registration number

NCT04336891; date of registration: April 7, 2020.
Time-Programmed Delivery of Sorafenib and Anti-CD47 Antibody via a Double-Layer-Gel Matrix for Postsurgical Treatment of Breast Cancer
Authors: Huang Liping , Zhang Yiyi , Li Yanan , Meng Fanling , Li Hongyu , Zhang Huimin , Tu Jiasheng , Sun Chunmeng , Luo Liang
Published: June 2021

The highly immunosuppressive microenvironment after surgery has a crucial impact on the recurrence and metastasis in breast cancer patients. Programmable delivery of immunotherapy-involving combinations through a single drug delivery system is highly promising, yet greatly challenging, to reverse postoperative immunosuppression. Here, an injectable hierarchical gel matrix, composed of dual lipid gel (DLG) layers with different soybean phosphatidylcholine/glycerol dioleate mass ratios, was developed to achieve the time-programmed sequential delivery of combined cancer immunotherapy. The outer layer of the DLG matrix was thermally responsive and loaded with sorafenib-adsorbed graphene oxide (GO) nanoparticles. GO under manually controlled near-infrared irradiation generated mild heat and provoked the release of sorafenib first to reeducate tumor-associated macrophages (TAMs) and promote an immunogenic tumor microenvironment. The inner layer, loaded with anti-CD47 antibody (aCD47), could maintain the gel state for a much longer time, enabling the sustained release of aCD47 afterward to block the CD47-signal regulatory protein α (SIRPα) pathway for a long-term antitumor effect. In vivo studies on 4T1 tumor-bearing mouse model demonstrated that the DLG-based strategy efficiently prevented tumor recurrence and metastasis by locally reversing the immunosuppression and synergistically blocking the CD47-dependent immune escape, thereby boosting the systemic immune responses.
Contours of a ‘Post-Critical’ Cartography—A Contribution to the Dissemination of Sociological Cartographic Research
Authors: Kühne Olaf
Published: June 2021

Since the 1980s, ‘critical cartography’ has been developing. Its merits lie in its awareness of the socially constructed nature of cartographic representations, the power relations involved, and the process-bound nature of cartographic practices. The ‘post-critical’ cartography proposed here takes up these merits but does so without following the categorical rejection of positivist ‘traditional’ cartography or the moral demarcation of what can and cannot be represented as well as the subordination of theories to the ‘critical’ paradigm. Instead, the ‘post-critical’ approach relies on the struggle for suitable theoretical frameworks—the normative reference horizon within the endeavor of cartography is the enhancement of life chances. In this respect, the prefix ‘post’ refers not only to a temporal ‘after’, but also to the perpetuation of central concerns of ‘critical’ cartography, simultaneously freeing it from such limitations.
Validation of the German Day-to-Day Impact of Vaginal Aging (DIVA) Questionnaire in Peri- and Postmenopausal Women
Authors: Gabes Michaela , Stute Petra , Apfelbacher Christian
Published: June 2021

Background

The Day-to-Day Impact of Vaginal Aging (DIVA) questionnaire is a validated patient-reported outcome measure (PROM) capturing the impacts of vaginal symptoms in postmenopausal women.

Aim

We aimed to psychometrically validate the German version of the DIVA questionnaire.

Methods

Data was collected online and by paper-pencil. We ran confirmatory factor analyses to confirm the a priori four-factor structure of the DIVA. Internal consistency was calculated using Cronbach's alpha. Correlations with other outcome measures such as the Patient Health Questionnaire-4 (PHQ-4), the SF-12 SOEP (socio-economic panel) version and self-created anchor questions were calculated regarding convergent validity. Known groups regarding age, home country and disease severity were analyzed. Test-retest reliability after 1 week and responsiveness after 4 weeks were only descriptively assessed due to low sample sizes.

Main Outcome Measures

The DIVA questionnaire, the Menopause Rating Scale (MRS II), the PHQ-4 and the SF-12 SOEP version were the main outcome measures.

Results

185 postmenopausal women reporting vaginal complaints participated in the survey. The mode of administration did not influence the severity of vaginal symptoms. The four-factor structure of the DIVA could be confirmed and the model fit indicated sufficient structural validity. Furthermore, strong internal consistency in all of the DIVA domains was found. Regarding convergent validity, no hypothesis has failed completely. The results regarding known-groups validity were mostly in line with our a priori hypotheses. Descriptive evidence for sufficient test-retest reliability and responsiveness was given, however, the sample size for the assessment of those two measurement properties was low.

Conclusion

This study supports the excellent structural validity, internal consistency and construct validity of the German version of the DIVA questionnaire. It can be recommended for the assessment of the impacts of vaginal symptoms in postmenopausal women in future clinical GSM trials.

Gabes M, Stute P, Apfelbacher C. Validation of the German Day-to-Day Impact of Vaginal Aging (DIVA) Questionnaire in Peri- and Postmenopausal Women. Sex Med 2021;9:100382
All the Math You Missed
Authors: Garrity Thomas A.
Published: June 2021

Beginning graduate students in mathematical sciences and related areas in physical and computer sciences and engineering are expected to be familiar with a daunting breadth of mathematics, but few have such a background. This bestselling book helps students fill in the gaps in their knowledge. Thomas A. Garrity explains the basic points and a few key results of all the most important undergraduate topics in mathematics, emphasizing the intuitions behind the subject. The explanations are accompanied by numerous examples, exercises and suggestions for further reading that allow the reader to test and develop their understanding of these core topics. Featuring four new chapters and many other improvements, this second edition of All the Math You Missed is an essential resource for advanced undergraduates and beginning graduate students who need to learn some serious mathematics quickly.
The Sea in the British Musical Imagination
Authors: Adams Byron , Doctor Jenny , Kuykendall James Brooks , McGuire Charles Edward , McLamore Alyson , Niebur Louis , Oates Jennifer , Thomson Aidan , Vickers Justin , Winkler Amanda Eubanks , Wilkins Frances
Published: June 2021

For centuries, the sea and those who sail upon it have inspired the imaginations of British musicians. Generations of British artists have viewed the ocean as a metaphor for the mutable human condition - by turns calm and reflective, tempestuous and destructive - and have been influenced as much by its physical presence as by its musical potential. But just as geographical perspectives and attitudes on seascapes have evolved over time, so too have cultural assumptions about their meaning and significance. Changes in how Britons have used the sea to travel, communicate, work, play, and go to war have all irresistibly shaped the way that maritime imagery has been conceived, represented, and disseminated in British music. By exploring the sea's significance within the complex world of British music, this book reveals a network of largely unexamined cultural tropes unique to this island nation. The essays are organised around three main themes: the Sea as Landscape, the Sea as Profession, and the Sea as Metaphor, covering an array of topics drawn from the seventeenth century to the twenty-first. Featuring studies of pieces by the likes of Purcell, Arne, Sullivan, Vaughan Williams, and Davies, as well as examinations of cultural touchstones such as the BBC, the Scottish fishing industry, and the Aldeburgh Festival, The Sea in the British Musical Imagination will be of interest to musicologists as well as scholars in history, British studies, cultural studies, and English literature. ERIC SAYLOR is Associate Professor of Musicology at Drake University. CHRISTOPHER M. SCHEER is Assistant Professor of Musicology at Utah State University. CONTRIBUTORS: Byron Adams, Jenny Doctor, Amanda Eubanks Winkler, James Brooks Kuykendall, Charles Edward McGuire, Alyson McLamore, Louis Niebur, Jennifer Oates, Eric Saylor, Christopher M. Scheer, Aidan J. Thomson, Justin Vickers, Frances Wilkins
Roger Morrice and the Puritan Whigs
Authors: Goldie Mark
Published: June 2021

Mark Goldie's authoritative and highly readable introduction to the political and religious landscape of Britain during the turbulent era of later Stuart rule.
The Wardle Family and its Circle: Textile Production in the Arts and Crafts Era
Authors: King Brenda M.
Published: June 2021

The history of an entrepreneurial family whose work influenced followers of the Arts and Crafts Movement, Gothic Revivalism, Art Needlework and Aestheticism
Priests and their Books in Late Anglo-Saxon England
Authors: Dyson Gerald P.
Published: June 2021

Fresh perspectives on the English clergy, their books, and the wider Anglo-Saxon church.
Sectional Distribution Patterns of Cd, Ni, Zn, and Cu in the North Pacific Ocean: Relationships to Nutrients and Importance of Scavenging
Authors: Zheng Linjie , Minami Tomoharu , Takano Shotaro , Ho Tung‐Yuan , Sohrin Yoshiki
Published: June 2021

The North Pacific Ocean is located at the end of the thermohaline circulation of deep water. This study reports on basin‐scale full‐depth sectional distributions of total dissolvable (td), dissolved (d), and labile particulate (lp) Cd, Ni, Zn, and Cu along three transects: the GEOTRACES transects GP18 (165°E) and GP02 (47°N), and along 160°W. We find that scavenging is an important factor that significantly affects the distributions of dZn, dNi, and dCu, of which the magnitude of influence increases in the order of Cd < Ni, Zn < Cu. The relationships between the four dissolved metals with Si(OH)4 and PO4 differed considerably from those in other oceans. The spot concentration ratio of dCd/PO4 was 0.34 ± 0.02 nmol/μmol (n = 296) in waters >800 m deep, which is in the range of the phytoplankton Cd/P ratio. This is indicative of the dominant effect of water circulation and biological processes on dCd distribution. The dissolved metals (dMs) to PO4 ratios of other examined metals were either partially or completely outside the range of typical biomass ratios. They generally increased with depth in waters >800 m deep; the magnitude of increase was the highest for Cu and moderate for Ni and Zn. Below 800 m, an increase in the apparent oxygen utilization from 150 to 300 μmol/kg was concurrent with a decrease in the dMs/PO4 ratios: 4 ± 3% for Cd, 21 ± 4% for Zn, 21 ± 3% for Ni, and 69 ± 7% for Cu.
Giant Seafloor Depressions Caused by Slope Failures and Bottom Currents on the Namibia Continental Margin
Authors: Wenau S. , Spiess V. , Zabel M.
Published: June 2021

More than 100 circular, elongate or crescent‐shaped very large seafloor depressions were found on the southern Namibian continental margin in water depths between 900 and 1700 m. These depressions show extraordinary sizes of up to 3 km diameter and 180 m depth. Multichannel seismic and bathymetric data show the influence of bottom currents on their morphology through prograding infills on the upcurrent and erosion on the downcurrent flanks, thus creating a crescent morphology in the largest depressions. Although their seafloor morphology resembles pockmarks related to seafloor fluid seepage, no indications for an active fluid flow system were observed in the area. Some depressions show extensive underlying cut‐and‐fill sequences that could be traced down to slope failure structures and deposits at depth. A correlation to ODP drill site 1085 indicates a continuous development of seafloor depressions for ∼10 Ma, documented by successive stages of infilling, erosion and size variations. Analysis of the seismic reflection data suggests that these depressions formed through the interaction of bottom currents with existing seafloor morphology. The equilibrium seafloor of the continental margin was initially disturbed by mass‐wasting events, common occurrences in the region. Subsequently, ongoing sedimentation in their vicinity was affected by ocean bottom currents, leading to the preservation and constant re‐shaping of seafloor depressions until recent times. This study thus highlights the ability of continental slope sedimentation under bottom‐current influence to produce unique seafloor features over long geological time scales.
Changes in the Magnetic Field Topology and the Dayside/Nightside Reconnection Rates in Response to a Solar Wind Dynamic Pressure Front: A Case Study
Authors: Boudouridis A. , Connor H. K. , Lummerzheim D. , Ridley A. J. , Zesta E.
Published: June 2021

One of the most significant observations associated with a sharp enhancement in solar wind dynamic pressure, , is the poleward expansion of the auroral oval and the closing of the polar cap. The polar cap shrinking over a wide range of magnetic local times (MLTs), in connection with an observed increase in ionospheric convection and the transpolar potential, led to the conclusion that the nightside reconnection rate is significantly enhanced after a pressure front impact. However, this enhanced tail reconnection has never been directly measured. We demonstrate the effect of a solar wind dynamic pressure front on the polar cap closure, and for the first time, measure the enhanced reconnection rate in the magnetotail, for a case occurring during southward background Interplanetary Magnetic Field (IMF) conditions. We use Polar Ultra‐Violet Imager (UVI) measurements to detect the location of the open‐closed field line boundary, and combine them with Assimilative Mapping of Ionospheric Electrodynamics (AMIE) potentials to calculate the ionospheric electric field along the polar cap boundary, and thus evaluate the variation of the dayside/nightside reconnection rates. We find a strong response of the polar cap boundary at all available MLTs, exhibiting a significant reduction of the open flux content. We also observe an immediate response of the dayside reconnection rate, plus a phased response, delayed by ∼15–20 min, of the nightside reconnection rate. Finally, we provide comparison of the observations with the results of the Open Geospace General Circulation Model (OpenGGCM), elucidating significant agreements and disagreements.
Opposite Symmetry in the Lithospheric Structure of the Alboran and Algerian Basins and Their Margins (Western Mediterranean): Geodynamic Implications
Authors: Kumar Ajay , Fernàndez Manel , Vergés Jaume , Torne Montserrat , Jiménez‐Munt Ivone
Published: June 2021

The geodynamic evolution of the Western Mediterranean for the past 35 My is a matter of debate. Present‐day structure and composition of the lithosphere and sublithospheric mantle may help in constraining the geodynamic evolution of the region. We use an integrated geophysical‐petrological modeling to derive and compare the present‐day thermal, density and compositional structure of the lithosphere and sublithospheric mantle along two NNW‐SSE oriented transects crossing the back‐arc Alboran and Algerian basins, from onshore Iberia to the northern Africa margin. The crust is constrained using available seismic data and geological cross‐sections, whereas seismic tomography and mantle xenoliths constrain the upper mantle structure and composition. Results show a thick crust (37 and 30 km) and a relative deep LAB (130 and 150 km) underneath the HP/LT metamorphic units of the Internal Betics and Greater Kabylies, respectively, which contrast with the 16 km thick magmatic crust of the Alboran Basin and the 10 km thick oceanic crust of the Algerian Basin. The sharp change in lithosphere thickness, from the orogenic wedge to the back‐arc basins, contrasts with the gentler lithosphere thickening toward the respective opposed margins. Our results confirm the presence of detached slabs ∼400 °C colder than upper mantle and a fertile composition than the continental lithospheric mantle beneath the External Betics and Saharan Atlas. Presence of detached quasi‐vertical sublithospheric slabs dipping toward the SSE in the Betics and toward the NNW in the Kabylies and the opposed symmetric lithospheric structure support an opposite dipping subduction and retreat of two adjacent segments of the Jurassic Ligurian‐Tethys realm.
Asymmetric Backward Peaking Radiation Pattern From a Relativistic Particle Accelerated by Lightning Leader Tip Electric Field
Authors: Yücemöz Mert , Füllekrug Martin
Published: June 2021

Terrestrial Gamma ray Flashes exhibit slopes of ionizing radiation associated with bremsstrahlung. Bremsstrahlung has a continuous spectrum of radiation from radio waves to ionizing radiation. The Poynting vector of the emitted radiation, that is, the radiation pattern around a single particle under the external lightning electric field during interaction with other particles or atoms, is not quite well known. The overall radiation pattern arises from the combination of radiation of parallel and perpendicular motions of a particle caused by the acceleration from the lightning electric field and the bremsstrahlung. The calculations and displays of radiation patterns are generally limited to a low‐frequency approximation for radio waves and separate parallel and perpendicular motions. Here, we report the radiation patterns of combined parallel and perpendicular motions from accelerated relativistic particles at low and high frequencies of the bremsstrahlung process with an external lightning electric field. The primary outcome is that radiation patterns have four relative maxima with two forward peaking and two backward peaking lobes. The asymmetry of the radiation pattern, that is, the different intensities of forward and backward peaking lobes, are caused by the Doppler effect. A novel outcome is that bremsstrahlung has an asymmetry of the four maxima around the velocity vector caused by the curvature of the particle's trajectory as it emits radiation. This mathematical modeling helps to better understand the physical processes of a single particle's radiation pattern, which might assist the interpretation of observations with networks of radio receivers and arrays of γ‐ray detectors.
Magnetotelluric Sampling and Geoelectric Hazard Estimation: Are National‐Scale Surveys Sufficient?
Authors: Murphy Benjamin S. , Lucas Greg M. , Love Jeffrey J. , Kelbert Anna , Bedrosian Paul A. , Rigler E. Joshua
Published: June 2021

At present, the most reliable information for inferring storm‐time ground electric fields along electrical transmission lines comes from coarsely sampled, national‐scale magnetotelluric (MT) data sets, such as that provided by the EarthScope USArray program. An underlying assumption in the use of such data is that they adequately sample the spatial heterogeneity of the surface relationship between geomagnetic and geoelectric fields. Here, we assess the degree to which the density of MT data sampling affects geoelectric hazard assessments. For electrical transmission networks in each of four focus regions across the contiguous United States, we perform two parallel band‐limited (101–103 s) hazard analyses: one using only USArray‐style (∼70‐km station spacing) MT data, and one incorporating denser (≪70‐km station spacing) MT data. We find that the use of USArray‐style MT sampling alone provides a useful first‐order estimate of integrated geoelectric fields along electrical transmission lines. However, we also find that the use of higher density MT data can in some areas lead to order‐of‐magnitude differences in line‐averaged electric field estimates at the level of individual transmission lines and can also yield significant differences in subregional hazard patterns. As we demonstrate using variogram plots, these differences reflect short‐spatial‐scale variability in Earth conductivity, which in turn reflects regional lithotectonic structure and history. We also provide a cautionary example in the use of electrical conductivity models to predict dense MT data; although valuable for hazard applications, models may only be able to reproduce surface geoelectric fields as captured by the MT data from which they were derived.
Economics of Optimal Reservoir Capacity Determination, Sediment Management, and Dam Decommissioning
Authors: Niu Yuan , Shah Farhed A.
Published: June 2021

The lifetime net economic contribution of a dam that is subject to sedimentation is likely to depend on the storage capacity of its reservoir, how fast the capacity is lost to sedimentation, and the cost of ultimate decommissioning of the dam. A model is developed for determining the size of initial reservoir capacity of a dam to maximize lifetime net benefits, while allowing for the possibility of sediment management to extend its useful life, and accounting for dam decommissioning costs incurred when this life ends. The model is applied to a proposed hydropower dam. Baseline results are compared with those obtained from building the dam at its designed reservoir capacity. Sensitivity analysis with respect to key economic and technical parameters is also carried out to characterize differences in solutions to the cases with and without sediment management. The overall goal is to improve our understanding of optimal dam sizing under different circumstances.
Polarimetric Portraits
Authors: Raney R. Keith
Published: June 2021

“Fully polarimetric” in its original radio science usage denotes a receiving instrument's ability to measure the four‐parameter Stokes vector characterizing the polarimetric properties of an electro‐magnetic (EM) field. In contrast, radar remote sensing specialists use “fully polarimetric” to apply exclusively to radars that evaluate the four complex scattering matrix elements. To disambiguate, polarimetric portrait is suggested, defined to be the Stokes vector of an unbiased EM field. For a passive system, this new name applies without qualification to the four Stokes parameters seen through a passive dual‐channel receiver. For an active system, the scene's illumination must have equal weighting between any two orthogonal polarizations to generate a polarimetrically unbiased reflected EM field. The suggested terminology is applicable to a variety of disciplines, including radiometry, alternative polarimetric radar architectures, radar astronomy, weather radar, and GPS/GNSS reflectometry. Polarimetric portraits obtained by dual‐polarized and quadrature‐polarized radars are shown to be equal.
Observations from Space and Ground Reveal Clues About Lightning
Authors: Derouin Sarah
Published: June 2021

In a coordinated monitoring effort, scientists have uncovered the timing and triggering of high-energy lightning events in the sky.
Evolution of Mid‐latitude Density Irregularities and Scintillation in North America During the 7–8 September 2017 Storm
Authors: Nishimura Y. , Mrak S. , Semeter J. L. , Coster A. J. , Jayachandran P. T. , Groves K. M. , Knudsen D. J. , Nishitani N. , Ruohoniemi J. M.
Published: June 2021

Using the University Navstar Consortium (UNAVCO) Global Positioning System (GPS) receiver network in North America, we present 2‐D distributions of GPS radio signal scintillation in the mid‐latitude ionosphere during the 7–8 September 2017 storm. The mid‐latitude ionosphere showed a variety of density structures such as the storm enhanced density (SED) base and plume, main trough, secondary plume, and secondary trough during the storm main and early recovery phases. Enhanced phase and amplitude scintillation indices were observed at the density gradients of those structures. SuperDARN radar echoes were also enhanced at the density gradients. The collocation of the scintillation and HF radar echoes indicates that density irregularities developed across a wide range of wavelengths (tens of meters to tens of kilometers) in the mid‐latitude density structures. The density gradients and irregularities were also detected by Swarm and DMSP as in‐situ density structures that disturbed the GPS signals. The irregularities were a substantial fraction (∼10%–50%) of the background density. The density irregularity had a power law spectrum with slope of ∼ −1.8, suggesting that gradient drift instability (GDI) contributed to turbulence formation. Both high‐latitude and low‐latitude processes likely contributed to forming the mid‐latitude density structures, and the mid‐latitude scintillation occurred at the interface of high‐latitude and low‐latitude forcing.
Subsurface Oceanic Structure Associated With Atmospheric Convectively Coupled Equatorial Kelvin Waves in the Eastern Indian Ocean
Authors: Azaneu Marina , Matthews Adrian J. , Baranowski Dariusz B.
Published: June 2021

Atmospheric convectively coupled equatorial Kelvin waves (CCKWs) are a major tropical weather feature strongly influenced by ocean–atmosphere interactions. However, prediction of the development and propagation of CCKWs remains a challenge for models. The physical processes involved in these interactions are assessed by investigating the oceanic response to the passage of CCKWs across the eastern Indian Ocean and Maritime Continent using the NEMO ocean model analysis with data assimilation. Three‐dimensional life cycles are constructed for “solitary” CCKW events. As a CCKW propagates over the eastern Indian Ocean, the immediate thermodynamic ocean response includes cooling of the ocean surface and subsurface, deepening of the mixed layer depth, and an increase in the mixed layer heat content. Additionally, a dynamical downwelling signal is observed two days after the peak in the CCKW westerly wind burst, which propagates eastward along the Equator and then follows the Sumatra and Java coasts, consistent with a downwelling oceanic Kelvin wave with an average phase speed of 2.3 m s−1. Meridional and vertical structures of zonal velocity anomalies are consistent with this framework. This dynamical feature is consistent across distinct CCKW populations, indicating the importance of CCKWs as a source of oceanic Kelvin waves in the eastern Indian Ocean. The subsurface dynamical response to the CCKWs is identifiable up to 11 days after the forcing. These ocean feedbacks on time scales longer than the CCKW life cycle help elucidate how locally driven processes can rectify onto longer time‐scale processes in the coupled ocean–atmosphere system.
Effects of Mosaic Representation of Land Use/Land Cover on Skin Temperature and Energy Fluxes in Noah‐MP Land Surface Model Over China
Authors: Zhang Guo , Li Jianduo , Zhou Guangsheng , Cai Xitian , Gao Wenhua , Peng Xindong , Chen Yueli
Published: June 2021

The representations of land use/land cover (LULC) play an important role in land surface models (LSMs) for the simulation of the energy flux partition, soil moisture redistribution, and runoff generation. This study was designed to investigate the regional effects of mosaic LULC representations on skin temperature (Ts) and energy fluxes over China at three horizontal resolutions and how these effects changed with climate regimes, using Noah with multiparameterization (Noah‐MP) LSM. The current officially released Noah‐MP only considered the most abundant LULC type within one model grid. In this study, the mosaic method considering all the LULC types existing in one model grid was implemented into Noah‐MP. Against the reference data (including MODIS land surface temperature products, FLUXCOM energy flux data and Numerical Terra dynamic Simulation Group evapotranspiration data), the mosaic method generally performed better than the default method and reduced the root‐mean‐squared‐error of Ts and energy fluxes significantly over urban region. The mosaic method affected the Ts and energy fluxes by changing leaf area index and soil moisture, mainly by the former. The warm (monthly mean air temperature larger than 10 °C) and relatively humid climate (annual total precipitation larger than 200 mm) could enlarge the effect of mosaic method on Ts and energy fluxes. The mosaic method reduced discrepancies of Ts and energy fluxes among three horizontal resolutions (0.0625°, 0.25°, and 0.50°), especially over the heterogeneous vegetated and urban region.
Comparison Between Eddy‐Covariance and Flux‐Gradient Size‐Resolved Dust Fluxes During Wind Erosion Events
Authors: Dupont S. , Rajot J.‐L. , Lamaud E. , Bergametti G. , Labiadh M. , Khalfallah B. , Bouet C. , Marticorena B. , Fernandes R.
Published: June 2021

Estimating accurately dust emission flux during aeolian erosion events is crucial for quantifying the amount of dust in the atmosphere. The rare existing field experiments quantifying such flux were mainly performed using the flux‐gradient (FG) method. Here, we present the first intercomparison of the size‐resolved dust fluxes estimated by both the FG and the eddy‐covariance (EC) methods during several erosion events. Both methods were applied simultaneously during the WIND‐O‐V (WIND erOsion in presence of sparse Vegetation)'s 2017 field experiment over an isolated erodible bare plot in South Tunisia. Overall, both methods predict similar dust fluxes for particle smaller than about 4 μm. For coarser particles, the EC method predicts a smaller dust flux than the FG method. Factors explaining this difference are discussed such as the different sampling heads used by the dust particle counters of both methods, or the possible weakening of the constant dust flux layer at the location of the upper dust particle counter of the FG method. This intercomparison highlights the difficulties and advantages of each method as well as their complementarity.