bluuebunny/crossref_metadata_2025 huggingface dataset:
PDX models of relapsed pediatric AML preserve global gene expression patterns and reveal therapeutic targets
Authors: Wunderlich Mark , Chen Jing , Sexton Christina , Manning Nicole , Byerly Luke , O’Brien Eric , Perentesis John P. , Mulloy James C. , Mizukawa Benjamin
Published: February 2022

As patient-derived xenograft (PDX) models of acute myeloid leukemia (AML) become increasingly common tools for preclinical evaluation of targeted therapies it becomes important to consider the fidelity with which this system recapitulates the disease state found in patients. Gene expression profiling of patient blasts has been successfully used to identify distinct subtypes of AML to uncover sub-type specific vulnerabilities and to predict response to therapy and outcomes. Currently, there is little information regarding how well PDX models of AML mimic global gene expression patterns found in patients. In order to address this point, we performed detailed RNA-Seq analysis of data obtained from a diverse series of pediatric AML PDXs, separately and compared to primary patient data. When unsupervised clustering was applied to the PDX sample dataset, we found grouping associated with KMT2A (MLL) gene status. Additionally, in combined analysis, PDX samples were found to align with primary patient samples harboring similar genetics. We found a strong correlation of expression levels of nearly all expressed transcripts in PDX and patient datasets thus demonstrating faithful recapitulation of gene expression signatures. Furthermore, paired patient/PDX samples showed strong concordance, suggesting retention of sample-specific gene expression in immune deficient mice. Comparisons of PDX models propagated in NOD/SCID/IL2rg-/-(NSG) mice compared to NSG mice with transgenic expression of human SCF, GM-CSF, and IL-3 (NSGS) revealed minimal differences related to increased JAK/STAT and macrophage activation pathways in NSGS. Additionally, a unique RAM immunophenotype associated expression signature pointed to discovery of cryptic CBFA2T3-GLIS2 rearrangement as the mechanistic driver mutation in two PDX models. Based on the relatively high BCL2 mRNA in these models, we tested the efficacy of venetoclax in combination with CPX-351 which resulted in reduced leukemia burden and prolonged survival. These results validate the PDX system as surrogate of the molecular signatures in high-risk pediatric AML and highlight this system’s utility for pre-clinical therapeutic discovery, especially in very rare subtypes of disease.
Anti-seed PNAs targeting multiple oncomiRs for brain tumor therapy
Authors: Wang Yazhe , Malik Shipra , Suh Hee-Won , Xiao Yong , Deng Yanxiang , Fan Rong , Huttner Anita , Bindra Ranjit S , Saltzman W Mark , Bahal Raman
Published: February 2022

Glioblastoma (GBM) is one of the most lethal malignancies in the United States with poor survival and high recurrence rates, suggesting the need for approaches targeting the most important molecular drivers of tumor growth. Here, we aimed to simultaneously target oncomiRs 10b and 21, which have been reported to drive the aggressive growth and invasiveness of GBM. We designed short (8-mer bases) gamma-(γ)-modified peptide nucleic acids (sγPNAs), which target the seed region of oncomiRs 10b and 21 with high affinity. We entrapped these anti-miR sγPNAs in nanoparticles (NPs) formed from a block copolymer of poly(lactic acid) and hyperbranched polyglycerol (PLA-HPG); the NPs were also functionalized with aldehydes to produce bioadhesive NPs. We have previously shown that these bioadhesive NPs (BNPs) produce superior transfection efficiency, with a tropism for tumor cells. The sγPNA BNPs showed superior anti-miR efficacy in comparison to the regular full length PNA BNPs in vitro. When combined with temozolomide, sγPNA BNPs administered via convention-enhanced delivery (CED) inhibited the growth of intracranial tumors and significantly improved the survival of animals (>120 days). RNA sequencing analysis revealed the role of vascular endothelial growth factor A (VEGFA) and integrin beta 8 (ITGB8), direct targets of both miR-10b and miR-21, in mediating the tumor growth. Hence, we established that BNPs loaded with anti-seed sγPNAs targeting multiple oncomiRs is a promising approach to improve the treatment of GBM, with a potential to personalize treatment based on tumor specific oncomiRs.

Targeting oncomiRs 21 and 10b to improve GBM survival

Glioblastoma (GBM) is an aggressive malignant disorder with high recurrence rates and poor survival. Here, we aimed to simultaneously inhibit two aberrant oncomiRs—miR 21 and miR 10b—which have been previously associated with GBM invasiveness and progression. We synthesized short, gamma-modified peptide nucleic acids (sγPNA) targeted to the miR seed regions and loaded the sγPNAs into bioadhesive nanoparticles (BNPs). When the sγPNA-BNPs were added to cultured tumor cells, we observed significant reduction of target oncomiRs and increase of apoptosis in vitro. When delivered in vivo by convection-enhanced delivery, sγPNA BNPs dramatically increased the survival in two orthotopic (intracranial) mouse models of GBM. Moreover, the combination of sγPNA BNPs with temozolomide (TMZ) increased the survival of mice with GBM beyond the planned endpoint (120 days) with significant improvements in histopathology. The proposed strategy of sγPNA BNP with TMZ provides an alternative, promising approach for treatment of GBM.
Vitamin D receptor cistrome-transcriptome analyses establishes quantitatively distinct receptor genomic interactions in African American prostate cancer regulated by BAZ1A
Authors: Siddappa Manjunath , Hussain Shahid , Wani Sajad A. , Tang Hancong , Gray Jaimie S. , Jafari Hedieh , Wu Hsuchang , Long Mark D. , Elhussin Isra , Karanam Balasubramanyam , Wang Honghe , Morgan Rebecca , Hardiman Gary , Adelani Isaacson B. , Rotimi Solomon O. , Murphy Adam R , Nonn Larisa , Davis Melissa B , Kittles Rick A , Halbert Chanita Hughes , Sucheston-Campbell Lara E. , Yates Clayton , Campbell Moray J.
Published: February 2022

Background

African American (AA) prostate cancer (PCa) appears uniquely sensitive to 1α,25(OH)2D3 signaling, compared to European American (EA) PCa, but the extent and impact of vitamin D receptor genomic functions remain poorly defined.

Results

A panel of EA and AA prostate epithelial cells (EA: HPr1-AR, LNCaP, AA: RC43N, RC43T, RC77N, RC77T) were analyzed with RIME to reveal the cell-specific composition of the VDR- complex. 1α,25(OH)2D3-dependent ATAC-Seq revealed the greatest impact on nucleosome positioning in RC43N and RC43T, with gain of nucleosome-free at enhancer regions. VDR ChIP-Seq identified stronger and more frequent VDR binding in RC43N and RC43T that was enriched for a larger and distinct motif repertoire, than EA cells. VDR binding significantly overlapped with core circadian rhythm transcription factors in AA cell line models. RNA-Seq also revealed significantly stronger 1α,25(OH)2D3 dependent VDR transcriptional responses enriched for circadian rhythm and inflammation networks in AA cells. Whilst RC43N was most responsive, RC43T displayed distorted responses. Significantly reduced BAZ1A/SMARCA5 in AA PCa samples was identified, and restored BAZ1A expression uniquely and significantly increased 1α,25(OH)2D3-regulated VDR targets in AA cells. These VDR- dependent cistrome-annotated genes were also uniquely and most significantly identified in three cohorts of AA PCa patients.

Conclusion

These data suggest VDR transcriptional control in the prostate is more potent and dynamic in AA men, and primed to govern inflammatory and circadian pathways. Reduced BAZ1A/SMARCA5 expression and/or reduced environmentally-regulated serum vitamin D3 levels suppress these actions. Therefore, the VDR axis lies at the cross-roads of biopsychosocial processes including stress responses, access to quality early detection and treatment, social determinants and that collectively contribute to PCa health disparities.
Striatal dopamine encodes the relationship between actions and reward
Authors: Hart G. , Burton T.J. , Nolan C.R. , Balleine B.W.
Published: February 2022

Although the role of striatal dopamine in Pavlovian conditioning and in habits has been reasonably well described, relatively little is known about its function in goal-directed action. In this study we trained hungry rats on two lever press actions for distinct food outcomes and recorded dopamine release in the dorsomedial striatum as these action-outcome associations were encoded and subsequently degraded. During initial training the lever press actions generated bilateral dopamine release that was found to reflect the predicted action value. This value was updated by the prediction error generated by the feedback produced by contact with the outcome, or its absence, after the press. Importantly, hemispheric dopamine release became increasingly lateralized across the course of training, with greater release in the hemisphere contralateral to the press. Using video analysis and multiple different measures, we could find no evidence that the degree of lateralized release was associated with movement; rather, we found that it tracked the strength of the action-outcome association, increasing and decreasing with increments and decrements in the contingency between specific actions and their consequences. Similar results emerged whether the rewards were delivered on ratio or interval schedules of reinforcement and whether we used unpaired outcome delivery or outcome-identity reversal to modify the specific contingencies. These findings suggest that, whereas moment-to-moment fluctuations in action value are reflected in bilateral dopamine release, a second signal broadcasts the overall strength of specific action-outcome relationships via the difference between contralateral and ipsilateral release during actions.
Profilin 1 deficiency drives mitotic defects and impairs genome stability
Authors: Scotto di Carlo Federica , Russo Sharon , Muyas Francesc , Mangini Maria , Pazzaglia Laura , Biamonte Flavia , De Luca Anna Chiara , Scotlandi Katia , Cortés-Ciriano Isidro , Gianfrancesco Fernando
Published: February 2022

Profilin 1 –encoded by PFN1– is a small actin-binding protein with a tumour suppressive role in various adenocarcinomas and pagetic osteosarcomas. However, its contribution to tumour development is not fully understood. Using fix and live cell imaging, we report that Profilin 1 inactivation results in multiple mitotic defects, manifested prominently by anaphase bridges, multipolar spindles, misaligned and lagging chromosomes, and cytokinesis failures. Accordingly, next-generation sequencing technologies highlighted that Profilin 1 knock-out cells display extensive copy-number alterations, which are associated with complex genome rearrangements and chromothripsis events in primary pagetic osteosarcomas with Profilin 1 inactivation. Mechanistically, we show that Profilin 1 is recruited to the spindle midzone at anaphase, and its deficiency reduces the supply of actin filaments to the cleavage furrow during cytokinesis. The mitotic defects are also observed in mouse embryonic fibroblasts and mesenchymal cells deriving from a newly generated knock-in mouse model harbouring a Pfn1 loss-of-function mutation. Furthermore, nuclear atypia is also detected in histological sections of mutant femurs. Thus, our results indicate that Profilin 1 has a role in regulating cell division, and its inactivation triggers mitotic defects, one of the major mechanisms through which tumour cells acquire chromosomal instability.
Universal structural requirements for maximal robust perfect adaptation in biomolecular networks
Authors: Gupta Ankit , Khammash Mustafa
Published: February 2022

Consider a biomolecular reaction network that exhibits robust perfect adaptation to disturbances from several parallel sources. The well-known Internal Model Principle of control theory suggests that such systems must include a subsystem (called the “internal model”) that is able to recreate the dynamic structure of the disturbances. This requirement poses certain structural constraints on the network which we elaborate in this paper for the scenario where constant-in-time disturbances maximally affect network interactions and there is model uncertainty and possible stochasticity in the dynamics. We prove that these structural constraints are primarily characterized by a simple linear-algebraic stoichiometric condition which remains the same for both deterministic and stochastic descriptions of the dynamics. Our results reveal the essential requirements for maximal robust perfect adaptation in biology, with important implications for both systems and synthetic biology. We exemplify our results through many known examples of robustly adapting networks and we construct new examples of such networks with the aid of our linear-algebraic characterization.
Keratin 8 is a scaffolding and regulatory protein of ERAD complexes
Authors: Pranke Iwona M. , Chevalier Benoit , Premchandar Aiswarya , Baatallah Nesrine , Tomaszewski Kamil F. , Bitam Sara , Tondelier Danielle , Golec Anita , Stolk Jan , Lukacs Gergely L. , Hiemstra Pieter S. , Dadlez Michal , Lomas David A. , Irving James A. , Delaunay-Moisan Agnes , van Anken Eelco , Hinzpeter Alexandre , Sermet-Gaudelus Isabelle , Edelman Aleksander
Published: February 2022

Early recognition and enhanced degradation of misfolded proteins by the endoplasmic reticulum (ER) quality control and ER-associated degradation (ERAD) cause defective protein secretion and membrane targeting, as exemplified for Z-alpha 1 antitrypsin (Z-A1AT), responsible for alpha-1-antitrypsin deficiency (A1ATD) and F508del-CFTR (cystic fibrosis transmembrane conductance regulator) responsible for cystic fibrosis (CF).

Prompted by our previous observation that decreasing Keratin 8 (K8) expression increased trafficking of F508del-CFTR to the plasma membrane, we investigated whether K8 impacts trafficking of soluble misfolded Z-A1AT protein. The subsequent goal of this study was to elucidate the mechanism underlying the K8-dependent regulation of protein trafficking, focusing on the ERAD pathway.

The results show that diminishing K8 concentration in HeLa cells enhances secretion of both Z-A1AT and wild type (WT) A1AT with a 13-fold and 4-fold increase, respectively. K8 down-regulation triggers ER failure and cellular apoptosis when ER stress is jointly elicited by conditional expression of the μsheavy chains, as previously shown for Hrd1 knock-out. Simultaneous K8 silencing and Hrd1 knock-out did not show any synergistic effect, consistent with K8 acting in the Hrd1-governed ERAD step. Fractionation experiments reveal that K8 is recruited to ERAD complexes containing Derlin2, Sel1 and Hrd1 proteins upon expression of Z/WT-A1AT and F508del-CFTR. Treatment of the cells with c407, a small molecule inhibiting K8 interaction, decreases K8 and Derlin2 recruitment to high-order ERAD complexes. This was associated with increased Z-A1AT secretion in both HeLa and Z-homozygous A1ATD patients’ respiratory cells. Overall, we provide evidence that K8 acts as an ERAD modulator. It may play a scaffolding protein role for early-stage ERAD complexes, regulating Hrd1-governed retrotranslocation initiation/ubiquitination processes. Targeting K8-containing ERAD complexes is an attractive strategy for the pharmacotherapy of A1ATD.
Evidence for close molecular proximity between reverting and undifferentiated cells
Authors: Zreika Souad , Fourneaux Camille , Vallin Elodie , Modolo Laurent , Seraphin Rémi , Moussy Alice , Ventre Elias , Bouvier Matteo , Ozier-Lafontaine Anthony , Bonnaffoux Arnaud , Picard Franck , Gandrillon Olivier , Giraud Sandrine
Published: February 2022

According to Waddington’s epigenetic landscape concept, the differentiation process can be illustrated by a cell akin to a ball rolling down from the top of a hill (proliferation state) and crossing furrows before stopping in basins or “attractor states” to reach its stable differentiated state. However, it is now clear that some committed cells can retain a certain degree of plasticity and reacquire phenotypical characteristics of a more pluripotent cell state. In line with this dynamic model, we have previously shown that differentiating cells (chicken erythrocytic progenitors (T2EC)) retain for 24 hours the ability to self-renew when transferred back in self-renewal conditions. Despite those intriguing and promising results, the underlying molecular state of those “reverting” cells remains unexplored. The aim of the present study was therefore to molecularly characterize the T2EC reversion process by combining advanced statistical tools to make the most of single cell transcriptomic data. For this purpose, T2EC, initially maintained in a self-renewal medium (0H), were induced to differentiate for 24h (24H differentiating cells); then a part of these cells was transferred back to the self-renewal medium (48H reverting cells) and the other part was maintained in the differentiation medium for another 24h (48H differentiating cells). For each time point, cell transcriptomes were generated using scRT-qPCR and scRNAseq. Our results showed a strong overlap between 0H and 48H reverting cells when applying dimensional reduction. Moreover, the statistical comparison of cell distributions and differential expression analysis indicated no significant differences between these two cell groups. Interestingly, gene pattern distributions highlighted that, while 48H reverting cells have gene expression pattern more similar to 0H cells, they retained traces of their engagement in the differentiation process. Finally, Sparse PLS analysis showed that only the expression of 3 genes discriminates 48H reverting and 0H cells. Altogether, we show that reverting cells return to an earlier molecular state almost identical to undifferentiated cells and demonstrate a previously undocumented physiological and molecular plasticity during the differentiation process, which most likely results from the dynamic behavior of the underlying molecular network.
Separation of RNA according to Size: Electrophoresis of RNA through Agarose Gels Containing Formaldehyde
Authors: Green Michael R. , Sambrook Joseph
Published: February 2022

Samples of RNA may be denatured by treatment with formamide and separated by electrophoresis through agarose gels containing formaldehyde. In this method, RNA is fractionated by electrophoresis through an agarose gel containing 2.2 m formaldehyde.
X-ray structure of the Rhodobacter sphaeroides reaction center with an M197 Phe→His substitution clarifies the properties of the mutant complex
Authors: Selikhanov Georgii , Fufina Tatiana , Guenther Sebastian , Meents Alke , Gabdulkhakov Azat , Vasilieva Lyudmila
Published: February 2022

The first steps of the global process of photosynthesis take place in specialized membrane pigment–protein complexes called photosynthetic reaction centers (RCs). The RC of the photosynthetic purple bacterium Rhodobacter sphaeroides, a relatively simple analog of the more complexly organized photosystem II in plants, algae and cyanobacteria, serves as a convenient model for studying pigment–protein interactions that affect photochemical processes. In bacterial RCs the bacteriochlorophyll (BChl) dimer P serves as the primary electron donor, and its redox potential is a critical factor in the efficient functioning of the RC. It has previously been shown that the replacement of Phe M197 by His strongly affects the oxidation potential of P (E
m P/P+), increasing its value by 125 mV, as well as increasing the thermal stability of RC and its stability in response to external pressure. The crystal structures of F(M197)H RC at high resolution obtained using various techniques presented in this report clarify the optical and electrochemical properties of the primary electron donor and the increased resistance of the mutant complex to denaturation. The electron-density maps are consistent with the donation of a hydrogen bond from the imidazole group of His M197 to the C2-acetyl carbonyl group of BChl PB. The formation of this hydrogen bond leads to a considerable out-of-plane rotation of the acetyl carbonyl group and results in a 1.2 Å shift of the O atom of this group relative to the wild-type structure. Besides, the distance between BChl PA and PB in the area of pyrrole ring I was found to be increased by up to 0.17 Å. These structural changes are discussed in association with the spectral properties of BChl dimer P. The electron-density maps strongly suggest that the imidazole group of His M197 accepts another hydrogen bond from the nearest water molecule, which in turn appears to form two more hydrogen bonds to Asn M195 and Asp L155. As a result of the F(M197)H mutation, BChl PB finds itself connected to the extensive hydrogen-bonding network that pre-existed in wild-type RC. Dissimilarities in the two hydrogen-bonding networks near the M197 and L168 sites may account for the different changes of the E
m P/P+ in F(M197)H and H(L168)F RCs. The involvement of His M197 in the hydrogen-bonding network also appears to be related to stabilization of the F(M197)H RC structure. Analysis of the experimental data presented here and of the data available in the literature points to the fact that the hydrogen-bonding networks in the vicinity of BChl dimer P may play an important role in fine-tuning the redox properties of the primary electron donor.
The role of local heteropolyhedral substitutions in the stoichiometry, topological characteristics and ion-migration paths in the eudialyte-related structures: a quantitative analysis
Authors: Aksenov Sergey M. , Kabanova Natalia A. , Chukanov Nikita V. , Panikorovskii Taras L. , Blatov Vladislav A. , Krivovichev Sergey V.
Published: January 2022

Topological analysis of the heteropolyhedral MT framework (where M and T are octahedral and tetrahedral cations, respectively) in the eudialyte-type structure and its derivatives was performed based on a natural tiling analysis of the 3D cation. To analyze the migration paths of sodium cations in these structures, the Voronoi method was used. The parental eudialyte-type MT framework is formed by isolated ZO6 octahedra, six-membered [M(1)6O24] rings of edge-sharing M(1)O6 octahedra, and two kinds of rings of tetrahedra, [Si3O9] and [Si9O27]. Different occupancies of M(2), M(3) and M(4) sites with variable coordination numbers by the additional Q, T* and M* cations, respectively, result in 12 different types of the MT framework. Based on the results of natural tilings calculations as well as theoretical analysis of migration paths, it is found that Na+ ions can migrate through six- and seven-membered rings, while all other rings are too small for the migration. In eight types of MT frameworks, Na+-ion migration and diffusion is possible at ambient temperature and pressure, while in four other types cages are connected by narrow windows and, as a result, the Na+ diffusion in them is complicated at ambient conditions because of the window diameter, but may be possible either at higher temperatures or under mild geological conditions for long periods of time.
Crystal structures of two dioxomolybdenum complexes stabilized by salan ligands featuring phenyl and cyclohexyl backbones
Authors: Trieu-Tran Tristhan , Martinez Stephenie N. , Brannon Jacob P. , Stieber S. Chantal E. , John Alex
Published: February 2022

Two cis-dioxomolybdenum complexes based on salan ligands with different backbones are reported. The first complex, dioxido{2,2′-[l,2-phenylenebis(iminomethylene)]bis(phenolato)}molybdenum(VI) dimethylformamide disolvate, [Mo(C20H18N2O2)O2]·2C3H7NO (PhLMoO2, 1b), features a phenyl backbone, while the second complex, (6,6′-{[(cyclohexane-1,2-diyl)bis(azanediyl)]bis(methylene)}bis(2,4-di-tert-butylphenolato))dioxidomolybdenum(VI) methanol disolvate, [Mo(C36H56N2O2)O2]·2CH3OH (CyLMoO2, 2b), is based on a cyclohexyl backbone. These complexes crystallized as solvated species, 1b·2DMF and 2b·2MeOH. The salan ligands PhLH2 (1a) and CyLH2 (2a) coordinate to the molybdenum center in these complexes 1b and 2b in a κ2
N,κ2
O fashion, forming a distorted octahedral geometry. The Mo—N and Mo—O distances are 2.3475 (16) and 1.9567 (16) Å, respectively, in 1b while the corresponding measurements are Mo—N = 2.3412 (12) Å, and Mo—O = 1.9428 (10) Å for 2b. A key geometrical feature is that the N—Mo—N angle of 72.40 (4)° in CyLMoO2 is slightly less than that of the PhLMoO2 angle of 75.18 (6)°, which is attributed to the flexibility of the cyclohexane ring between the nitrogen as compared to the rigid phenyl ring in the PhLMoO2.
Study of wake characteristics behind an oscillating NACA 0012 airfoil in deep dynamic stall regime
Authors: D. Surekha Rathi Samundi , R. Rajasekar
Published: January 2022

Purpose

This study aims to investigate the wake behind an oscillating airfoil at a various angle of incidence and Reynolds number in a deep dynamic stall condition.

Design/methodology/approach

NACA 0012 airfoil is allowed to undergo harmonic pitching motion about the quarter chord axis at Reynolds numbers of 0.5 * 105, 1.17 * 105, 1.7 * 105 and 2.12 * 105, and the reduced frequency of 0.1. The experiments are conducted at a set of mean and amplitude angle of attack that covered the angle of incidence from −5° to 25°. The wake rake is placed at a distance of one chord from the trailing edge of the airfoil.

Findings

The hysteresis of the flow during the upstroke and the downstroke motion are captured. The huge growth in the velocity defect and the wake thickness beyond the angle of attack of 15° explicate the appearance of the strong unsteady effects on the wake. The results also show that at the reduced frequency of 0.1, the wake structure is of drag producing type due to the momentum deficit.

Originality/value

Streamwise velocity profile and the turbulent intensity profiles are presented to show the effects of Reynolds number and angle of incidence on the wake behind the oscillating airfoil at the reduced frequency of 0.1, and in the intermediate range of Reynolds number is the novelty of the study.
Steady state solution of NFC model with nonlinear load using PEEC
Authors: Kvasnicka Samuel , Bauernfeind Thomas , Baumgartner Paul , Torchio Riccardo
Published: January 2022

Purpose

The purpose of this paper is to show that the computation of time-periodic signals for coupled antenna-circuit problems can be substantially accelerated by means of the single shooting method. This allows an efficient analysis of nonlinearly loaded coupled loop antennas for near field communication (NFC) applications.

Design/methodology/approach

For the modelling of electrically small coupled field-circuit problems, the partial element equivalent circuit (PEEC) method shows to be very efficient. For analysing the circuit-like description of the coupled problem, this paper developed a generalised modified nodal analysis (MNA) and applied it to specific NFC problems.

Findings

It is shown that the periodic steady state (PSS) solution of the resulting differential-algebraic system can be computed very time efficiently by the single shooting method. A speedup of roughly 114 to conventional transient approaches can be achieved.

Practical implications

The proposed approach appears to be an efficient alternative for the computation of time PSS solutions for nonlinear circuit problems coupled with discretised conductive structures, where the homogeneous solution is not of interest.

Originality/value

The present paper explores the implementation and application of the shooting method for nonlinearly loaded coupled antenna-circuit problems based on the PEEC method and shows the efficiency of this approach.
Electrical power components decomposition of periodic polyharmonic current
Authors: Bialobrzheskyi Oleksii V. , RodKin Dmytro , Gladyr Andrii
Published: January 2022

Purpose

At the current stage of electrical technology development, it is relevant to take into account the quality of electrical energy. It can be implemented if an assessed energy quality indicator is available. The amount of electrical energy is determined by active power, which is transmitted over a certain time period. In some cases, reactive power is included in the metering system. The distortion power is justifiably criticized and is not taken into account. The purpose of this paper consists in the substantiation of the indicator of the distortion of the periodic polyharmonic current electrical energy power, by separating from the instantaneous power such harmonics, which formed by same frequencies current and voltage harmonics.

Design/methodology/approach

Using the method of calculating linear polyharmonic current circuits, the following quantities are identified in instantaneous power: active, reactive and apparent powers of each harmonic. These components are known from references as canonical.

Findings

By the method of instantaneous power harmonic analysis, the components formed by current and voltage harmonics of the same frequency and different frequencies are distinguished.

Research limitations/implications

The RMS value of the instantaneous power due to current and voltage harmonics of different frequencies is justified in the work. This quantity allows you to distinguish the instantaneous power distortion level in comparison with the existing quantity.

Practical implications

The results can be used to assess the level of instantaneous power distortion level in commercial and technical metering systems.

Originality/value

The definition of instantaneous power distortion by extracting the canonical components from it and determining the root mean square value of the remainder is proposed.
Library anxiety among undergraduates in Nigeria
Authors: Adeeko Christy Olabisi , Adetimirin Airen
Published: January 2022

Purpose

Library anxiety is a phenomenon that is different from other academic anxiety, which has implication on physical use of libraries. This study aims to investigate the phenomenon of library anxiety among undergraduates in federal universities in North-central, Nigeria.

Design/methodology/approach

Descriptive survey of the correlational type was adopted for the study. Purposive sampling technique was used in selecting five conventional federal universities, three homogenous faculties and six departments through multistage sampling technique. Five percent of the undergraduates (797) were selected from a total sample of 15,933. The instrument used was measuring scale on library anxiety (MSLA) developed by Bostick (1992). Descriptive statistics such as percentage mean and standard deviation were used to analyse the research questions.

Findings

The findings revealed that majority of the undergraduates (85.0%) experienced moderate level of library anxiety across the universities at varying degree. The most prevalent aspect of the library anxiety experienced by the undergraduates was inadequate knowledge of the library (x. = 2.14).

Research limitations/implications

The study selected five conventional universities out of the seven federal universities in North-central, Nigeria.

Originality/value

Based on the findings, the study recommends library orientation programme for the undergraduates to increase their knowledge of the library. Likewise, the library staff should be more approachable and friendly so as to alleviate the library anxiety experienced by the undergraduates.
Inbound tourism demand elasticities of MENA countries: the role of internal and external conflicts
Authors: Usman Ojonugwa , Alola Andrew Adewale , Ike George
Published: February 2022

Purpose

In this paper, the authors investigate the inbound tourism demand elasticities of the Middle East and North African (MENA) countries. The authors emphasize the role of external and internal conflicts, world gross domestic product and relative prices over the period 1995–2017.

Design/methodology/approach

This study applies the heterogeneous panel data estimators based on the fully modified-OLS (FM-OLS), dynamic-OLS (DOLS) and the recently developed method of moments quantile regression (MMQR).

Findings

The empirical results indicate that the effect of external and internal conflicts on inbound tourism demand is negative and inelastic with external conflict having a stronger effect. The effect of both classifications of conflicts diminishes as the market share of the tourist destination increases. In addition, the role of the world GDP on tourism demand is positive and elastic, suggesting that tourism is a luxury good while an increase in relative prices diminishes inbound tourism demand.

Originality/value

The paper, therefore, concludes that if policy measures are not put in place to curtail incidences of conflicts, economic growth in these countries may suffer setbacks. This by implications could affect the attainment of the sustainable development goals (SDGs) targets.
Firm absorptive capacity: multidimensionality, drivers and contextual conditions
Authors: Hussain Nazim , Bhatti Waheed Akbar , Khan Sana Akbar , Arslan Ahmad , Tarba Shlomo Yedidia
Published: January 2022

Purpose

This paper aims to enrich absorptive capacity literature by specifically highlighting and adding environmental conditions and internationalisation process to the original conceptualisation.

Design/methodology/approach

The authors undertake a conceptual analysis and present an enhanced framework of absorptive capacity by integrating multiple literature streams. The authors have analysed the most relevant literature to provide underlying justifications for the proposed conceptual model.

Findings

Absorptive capacity ensures the long-term survival and success of a business. To develop absorptive capacity successfully, firms should focus on its various dimensions and existing intangible assets and external environment. The multidimensionality and richness of absorptive capacity is an under-explored area in the existing literature. The authors revisit the conceptualisation of absorptive capacity and add environmental conditions and the internationalisation process to the original conceptualisation. Absorptive capacity does not lead to a competitive advantage independent of its environment. To successfully develop it, firms have to adopt a holistic approach by considering the multi-dimensions, drivers and contextual conditions of absorptive capacity.

Originality/value

This study contributes by conceptualising absorptive capacity as a dynamic capability. It is one of the first studies to specifically propose a framework that combines antecedents (prior knowledge, combinative capabilities and IT capabilities), moderators (environmental conditions, namely, market and technological turbulence, competitiveness and the internationalisation process) and consequences (competitive advantage). The study offers a unique conceptualisation with implications for researchers and managers. As a result, managers will have a well-defined blueprint to create value by using firm capabilities.
Pursuing ways to improve the Brazilian procurement system: a comparison between the framework agreements in the United Kingdom and the Brazilian price registration system
Authors: Sorte Junior Waldemiro Francisco
Published: January 2022

Purpose

The purpose of this paper is to conduct a literature review on framework agreements, an instrument for demand aggregation adopted in the UK, to recommend improvements to the price registration system (SRP), a mechanism often used with reverse online auctions in Brazil envisaged to promote more flexibility in centralized tenders, allowing public bodies to establish contracts when the need arises, based on registered prices.

Design/methodology/approach

A literature review was undertaken to analyze the UK framework agreement approach and the Brazilian SRP. In addition, in-depth interviews with civil servants from the Brazilian Ministry of Economy were conducted to examine the SRP.

Findings

The experience with framework agreements in the UK reveals at least four ways to improve the Brazilian SRP: i) extending the legal maximum duration of a price registration minute (ARP) ; ii) allowing the registration of additional suppliers in the ARP, instead of only the first lowest bidder; iii) conducting mini-competitions when a contracting authority decides to use the ARP to enter into a contract; and iv) including additional criteria for awarding suppliers, in line with the most economically advantageous tender (MEAT) approach.

Social implications

The flow of government financial resources into procurement accounted for approximately 16.5% of gross domestic product in Brazil and for an average of 12% in OECD countries in 2017 (OECD, 2019: 135). Public procurement is a strategic function for enabling an efficient public services delivery and infrastructure deployment. It is, therefore, relevant to examine instruments of demand aggregation to improve the outcomes of public procurement.

Originality/value

Framework agreements are currently not used in Brazil. This paper examines the UK experience with framework agreements to propose potential improvements to the Brazilian SRP, a procurement instrument vastly used in the country.
Accommodating guests during pandemic times: a case-study of the Airbnb Host Community in Aarhus, Denmark
Authors: Fischer Simon Lind , Roelofsen Maartje
Published: February 2022

Purpose

This paper explores how Airbnb hosts' experiences with and responses to the coronavirus disease 2019 (COVID-19) health crisis may differ according to their motivations to host and to the type and spatial layout of their Airbnb accommodation. Based on these insights, the paper reflects on the lessons that are learned for the future of short-term rentals.

Design/methodology/approach

This is a qualitative multi-method small-scale case study, which relies on in-depth interviews and a focus group discussion carried out with a group of hosts affiliated to the Airbnb Host Community in Aarhus, Denmark. Informed by an interpretivist approach, the study aims to make sense of people's subjective experiences with hosting on the Airbnb platform, and how they have continued and adapted their hospitality practices during the pandemic.

Findings

Participants' adaptive practices vary according to their motivations to host and the type of accommodation that they rent out. Although all hosts in this study now implement more intensive cleaning practices, hosts who stay with their guests onsite tend to take stricter preventative measures to avoid contamination and transmission of the virus in their social interactions with guests. On the contrary, hosts who rent out their entire properties and have minimal contact with their guests found themselves less affected by the pandemic's impacts and have had a continued demand for their properties.

Social implications

The COVID-19 pandemic has unevenly affected Airbnb hosts. Hosts who share their homes with guests require different adaptations to their daily behaviour and cleaning practices at home than hosts who do not stay with their guests and rent out entire properties. However, unlike professional hosts who largely or solely rely on Airbnb for their income, occasional home-sharing hosts tend to be more flexible in coping with cancelled or fewer bookings.

Originality/value

This study provides novel insights into the uneven impact of the COVID-19 pandemic on participants in the platform economies of tourism. It contributes to existing literature on the impacts of the pandemic on Airbnb's operations by showing how hosts' adaptive practices are informed by their subjective living conditions and the type of accommodation they can offer their guests.
What might happen to the global stock market after Brexit?
Authors: Ren Zhiyuan
Published: February 2022

Purpose

The stock market is vulnerable to various exogenous factors, and its fluctuations can reflect the effects of political, economic and market factors. The purpose of this paper is therefore to choose the stock market as a representative to analyze the potential impact of the Brexit event on global financial markets and how to prevent the spread of risks across global financial markets.

Design/methodology/approach

This study chooses the auto-regressive moving average generalized autoregressive conditional heteroscedasticity (ARMA-GARCH) model to fit the financial series and uses it as the marginal distribution model to establish the vine copula model. The maximum spanning tree algorithm is used to select the optimal rattan structure model and pair-copula function. According to the final ARMA-GARCH-R-vine copula model, the tail correlation coefficients of the UK, France, Germany, USA and China stock markets are calculated and used to analyze their dependence structure.

Findings

The negative impact of the Brexit event on the British stock market is greater and is more likely to be transmitted to France and Germany. China and the USA are less likely to be impacted by the Brexit incident. The US financial market is more closely linked to France, and it may benefit from the Brexit incident due to the impact of the exchange rate. Although the Chinese stock market is directly connected to the British stock market, due to the existence of national macro-controls and other factors, it will be less affected by the Brexit incident. The main impact comes from the dual devaluation pressure on the RMB.

Originality/value

This paper selects the optimal combination model based on actual data, and the results obtained can accurately reflect the interdependence between relevant stock markets and can guide risk aversion in the financial investment field.
Adverse childhood experiences and gynaecological surgery
Authors: Rocca Walter A.
Published: January 2022

Linked article: This is a mini commentary on Panayotes Demakakos et al., pp. 1482–1490 in this issue. To view this article visit https://doi.org/10.1111/1471‐0528.17088
Discrimination of electrical tapes using ATR‐FTIR spectroscopy and chemometrics
Authors: Nimi Chongtham , Chophi Rito , Singh Rajinder
Published: February 2022

Electrical tapes are recovered during criminal investigations as physical evidence in cases of rape, kidnapping, and explosion incidents. The analysis of such evidence can provide an evidentiary link between the suspect, the victim, object, or the crime scene. In the present study, 25 brands of electrical tapes have been analyzed using ATR‐FTIR (attenuated total reflectance Fourier transform infrared) spectroscopy. Samples (1 cm2) were analyzed in the mid IR (Infrared) region from 4000–600 cm−1, and the functional groups of various components have been profiled. Chemometric methods‐PCA (principal component analysis) and PCA‐LDA (linear discriminant analysis) have been employed to interpret the data and classify the samples into its respective classes. Preliminary assessment of sample clustering due to similar chemical composition was visualized using PCA. PCA‐LDA applied for classification purpose yielded classification accuracy (calibration) of 92.98% for the adhesive side and 88% for the backing side. The validation results showed classification accuracy of 89.47% for the adhesive side and 84% for the backing side. Blind validation study was carried out using 5 samples, and classification accuracy of 100% and 80% was obtained for the adhesive and the backing side, respectively. In the current study, a preliminary substrate study was carried out, and the results showed that the backing samples could be more accurately matched to their correct source of origin than the adhesive side.
The impact of cost stickiness on financial reporting: evidence from income smoothing
Authors: Hartlieb Sven , Loy Thomas R.
Published: January 2022

This study investigates the impact of cost stickiness on income smoothing. Prior literature at the intersection between management and financial accounting has understood changes in cost behaviour as mere consequences of short‐term earnings management incentives. By considering income smoothing as the more complex earnings management strategy, we argue that resource adjustment strategies underlying cost behaviour might also have an impact on long‐term financial reporting choices. Specifically, asymmetric reactions of costs to sales changes should increase earnings volatility and thus restrict managers’ capabilities to report smooth income streams, which is supported by our empirical results. Additional tests reveal that cost stickiness primarily restricts opportunistic income smoothing and that the relationship depends on other factors such as the level of adjustment costs.
Comparative analysis between extra‐short implants (≤6 mm) and 6 mm‐longer implants: a meta‐analysis of randomized controlled trial
Authors: Fernandes GVO , Costa BMGN , Trindade HF , Castilho RM , Fernandes JCH
Published: January 2022

The goal of this systematic study was to compare the survival rate (SR), marginal bone loss (MBL) and clinical complications between extra‐short implants (≤6 mm) and 6‐mm‐longer implants in randomized clinical trials. A systematic electronic and manual search was performed using the PubMed, Web of Science, Scopus and DOAJ databases. A meta‐analysis was conducted to compare the SR and MBL between both groups. We have selected 17 studies out of 1016 articles for qualitative and quantitative analysis. The data from 956 patients and 1779 implants were used with an overall mean clinical follow‐up of 3.88 years ranging from 1 to 8 years. Overall, the SR of extra‐short implants (93.12%) was lower than the observed in 6‐mm‐longer implants (95.98%); however, there was no statistical significance on these findings (P > 0.10). MBL analysis showed that extra‐short implants and the 6‐mm‐longer group presented an average of −0.71 and −0.92 mm after 1‐year respectively. Three years follow‐up showed MBL of −0.42 mm (≤6 mm) and −0.43 mm (>6 mm); 5 years follow‐up showed an MBL of −0.69 mm (≤6 mm) and −0.46 mm (>6 mm); and after 8 years of follow‐up, it was found an MBL of −1.58 mm (≤6 mm) and −2.46 mm (>6 mm). Within the limitation of this study, the results indicated that SR of extra‐short implants was similar to 6‐mm‐longer implants. In contrast, MBL and the presence of clinical complications were observed at a lessened rate on extra‐short implants.