bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasmonic refractive index sensing enhanced by anapole modes in metal-dielectric nanostructure array
Authors: Wu Jingzhi , Li Zhihui , Li Mengwei , Wang Yanhong
Published: January 2021

Periodic nanostructures consisting of metal-dielectric nanostructures array are studied for refractive index (RI) sensing. The anapole mode of metal-dielectric structure is used to enhance plasmonic resonance and reduce energy losses. High sensitivity RI sensing can be achieved by the nanostructure with circular polarization illumination. Numerical results show that the sensor exhibit almost perfect linearity of resonance wavelength shift with RI ranging from 1.3 to 1.39 with sensitivity of 593 nm RIU−1. The proposed nanostructure could find applications in biomolecules manipulation and optical sensors.
Microstructural and mechanical characterization of powder-pack boronized Incoloy A286 superalloy
Authors: Türkmen İlyas , Korkmaz Adem
Published: January 2021

In this study, Incoloy A286 superalloy were boronized successfully by powder-pack boronizing process at 850 °C, 900 °C and 950 °C for 4 h by using a boronizing powder mixture containing H3BO3 as boron source. The thickness and morphology of the boride layer was identified by microstructural examinations. The boride layer with complex, compact and smooth morphology was formed on the surface of the samples. As a result of XRD analyses, it was determined that the compact boride layer was formed many phases such as FeB, Fe2B, Fe3B, CrB and Ni4B3 etc. It was specified that the average hardness value of the boride layer was approximately between 2400 and 3000 HV by microhardness tests. Also the graphs of friction coefficient and values of the specific wear rate were obtained by performing ball on disk wear tests. It was identified that the specific wear rate of boronized samples was approximately 9.5 times lower than that of unboronized samples.
Improvement in microstructure and wear-resistance of high chromium cast iron/medium carbon steel bimetal with high vanadium
Authors: Li Xuejun , Liu Ying , Zhou Tingchuan
Published: January 2021

In the present study, a high chromium cast iron (HCCI) with high content of vanadium (15 wt.%) as the wear resistance layer was fabricated on the medium carbon steel (MCS) substrate by laser cladding process. The effect of high vanadium addition on microstructure, phase, hardness and wear properties of bimetal were investigated. The results show that the microstructure of HCCI layer was significantly improved and refined with addition of high vanadium. No defect such as microcracks and unbonded regions was observed on the interface of the bimetal. The x-ray diffraction revealed that the HCCI (15 wt.% V) layer consists of α-Fe matrix, (Cr, Fe)7C3 and VC carbides. The SEM images shown that round-like VC particles uniformly distributed on the α-Fe matrix and (Cr, Fe)7C3 are of rod-like with distributed on grain boundary, such micromorphology makes it have higher hardness (883HV) and excellent wear resistance than HCCI layer without vanadium addition.
Selective laser melting of 1.2738 mold steel: densification, microstructure and microhardness
Authors: Yang Wei , Zhang Xiaoxun , Ma Fang , Dong Sensen , Jiang Juze
Published: January 2021

In this study, the effects of laser power and scanning speed on the relative density, microstructure and microhardness of selectively laser melted (SLM) 1.2738 mold steel were systematically investigated. The deposited energy density, which can express the change in these process parameters and the relative density with one curve, were found more reliable than volume energy density (VED) on the design of process parameters. With the same VED value, samples formed by the combination of a high laser power and scanning speed possess a higher densification than that formed by low laser power and scanning speed. High power may lead to keyhole pore formation. In the top of the molten pool, ultrafine cellular structure was formed, causing that the microhardness value of the top section was always higher than that of the side section.
Measurement of time-varying electron density of the plasma generated from a small-size cylindrical RDX explosion by Rayleigh microwave scattering
Authors: CHEN Hong , PAN Xuchao , HE Yong , JIAO Junjie , SHEN Jie , BEN Chi
Published: January 2021

It is challenging to measure the electron density of the unsteady plasma formed by charged particles generated from explosions in the air, because it is transient and on a microsecond time scale. In this study, the time-varying electron density of the plasma generated from a small cylindrical cyclotrimethylenetrinitramine (RDX) explosion in air was measured, based on the principle of microwave Rayleigh scattering. It was found that the evolution of the electron density is related to the diffusion of the detonation products. The application of the Rayleigh microwave scattering principle is an attempt to estimate the electron density in explosively generated plasma. Using the equivalent radius and length of the detonation products in the bright areas of images taken by a high-speed framing camera, the electron density was determined to be of the order of 1020 m−3. The delay time between the initiation time and the start of variation in the electron-density curve was 2.77–6.93 μs. In the time-varying Rayleigh microwave scattering signal curve of the explosively generated plasma, the electron density had two fluctuation processes. The durations of the first stage and the second stage were 11.32 μs and 19.20 μs, respectively. Both fluctuation processes increased rapidly to a peak value and then rapidly attenuated with time. This revealed the movement characteristics of the charged particles during the explosion.
Entangling the vibrational modes of two massive ferromagnetic spheres using cavity magnomechanics
Authors: Li Jie , Gröblacher Simon
Published: January 2021

We present a scheme to entangle the vibrational phonon modes of two massive ferromagnetic spheres in a dual-cavity magnomechanical system. In each cavity, a microwave cavity mode couples to a magnon mode (spin wave) via the magnetic dipole interaction, and the latter further couples to a deformation phonon mode of the ferromagnetic sphere via a nonlinear magnetostrictive interaction. We show that by directly driving the magnon mode with a red-detuned microwave field to activate the magnomechanical anti-Stokes process a cavity–magnon–phonon state-swap interaction can be realized. Therefore, if the two cavities are further driven by a two-mode squeezed vacuum field, the quantum correlation of the driving fields is successively transferred to the two magnon modes and subsequently to the two phonon modes, i.e., the two ferromagnetic spheres become remotely entangled. Our work demonstrates that cavity magnomechanical systems allow to prepare quantum entangled states at a more massive scale than currently possible with other schemes.
Arbitrary amplitude ion acoustic double layer in plasma with k-distributed electrons and negative ions
Authors: Kumar Kishan , Mishra M K
Published: January 2021

In this paper we have discussed the consequence of superthermal electrons and negative ion concentration on the arbitrary amplitude ion-acoustic double layers (IA-DLs) for plasma comprising the hot negative and positive ions with kappa distribution electrons. The energy equation is deduced for ion acoustic waves using Pseudo potential technique. We have investigated different parametric regimes for the existence of rarefactive and compressive ion acoustic DLs. The existence of double layers in term of minimum and maximum Mach number has calculated numerically. The effect of spectral index k on the amplitude of DLs and depth of Sagdeev potential has been discussed in detail. From numerical analysis, it is found that the compressive DLs exist at low values of α and rarefactive double layer exist at higher values of α. On the other hand, the effect of ionic temperature ratio (σ
1 and σ
2) plays significant role for the formation of double layer. Our analytical work also shows that the system supports coexistence of compressive and rarefactive DLs. It is also observed that the mass ratio

μ

affect the basic properties of DLs. We expect that the present results may be used to explain the ion-acoustic double layer in space plasma, where two ionic species and superthermal electrons are observed NO52.35g.
Elevated performance of binder-free Co3O4electrode for the supercapacitor applications
Authors: Sharma Meenakshi , Adalati Ravikant , Kumar Ashwani , Chawla Vipin , Chandra Ramesh
Published: January 2021

In the present work, we have designed a symmetric supercapacitor (SS) device by synthesizing a pseudocapacitive binder-free cobalt oxide (Co3O4) thin film based electrode using reactive DC magnetron sputtering technique. The thin film electrodes were characterized by x-ray diffraction, Raman spectroscopy and x-ray photoelectron spectroscopy to reveal the crystallographic details, stoichiometry, and electronic configuration, respectively. Furthermore, Co3O4thin film electrode is used for pseudocapacitor and electrochemically tested in 1M aqueous KOH electrolyte solution, in addition, a symmetric supercapacitor (SS) device was fabricated. It was found that the SS device exhibits tremendous electrochemical stability in terms of high capacitance and good cycling stability. The value of specific capacitance for Co3O4thin film electrodes and the SS device was calculated to be 392 Fg−1and 95 Fg−1, respectively, at a scan rate of 2 mAcm−2. The SS device exhibits high specific energy (29 W-hkg−1) along with comparable good specific power (4745 Wkg−1). In this work, the fabricated SS device demonstrates 91.40% cyclic and capacitance retention at 8 mAcm−2beyond 10 000 cycles. The excellent electrochemical stability and capacitive performance of the SS device suggest that it would be an ideal and potential candidate for energy storage applications in the future.
Biocompatibility assessment of silver chloride nanoparticles derived from Padina gymnospora and its therapeutic potential
Authors: Rajagopal Gopalan , Manivannan Nanthagopal , Sundararajan Mahalingam , Kumar Arumugam Ganesh , Senthilkumar Samuthirarajan , Mathivanan Narayanasamy , Ilango Sakkanan
Published: January 2021

The objective of the present work was to improve the biological activity of Padina gymnospora. In the current study, silver chloride nanoparticles have been synthesized using the aqueous extract of Padina gymnospora and further characterized by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, x-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy and atomic force microscope. Further, the hemolytic activity and eco-toxicity of silver chloride nanoparticles analyzed. The synthesized silver chloride nanoparticles were found to be mono-dispersed and spherical with an average size of 11.5–32.86 nm. The particles showed an anticancer effect in a dose-dependent manner against breast cancer cell line (MCF-7 cell lines) (IC50 = 31.37 μg ml−1). In addition, it showed the larvicidal activity against Aedes aegypti at a lower dose (3.92 μg ml−1) than that of the aqueous extract (13.01 μg ml−1). Nanoparticles also exhibited greater antimicrobial activity for both bacterial and fungal pathogens. The synthesized silver chloride nanoparticles showed a maximum zone of inhibition, i.e., 31 mm for Candida albicans followed and 27 mm for vancomycin resistance Enterococcus faecalis.The results suggest the possible use of synthesized silver nanoparticles with P. gymnospora as therapeutic agent for breast cancer, dengue vector control and as antimicrobial agent.
PRISA: a user-friendly software for determining refractive index, extinction co-efficient, dispersion energy, band gap, and thickness of semiconductor and dielectric thin films
Authors: Jena S , Tokas R B , Thakur S , Udupa D V
Published: January 2021

A user-friendly software PRISA has been developed to determine optical constants (refractive index and extinction co-efficient), dispersion parameters (oscillator energy and dispersion energy), absorption co-efficient, band gap and thickness of semiconductor and dielectric thin films from measured transmission spectrum, only. The thickness, refractive index, and extinction co-efficient of the films have been derived using Envelope method proposed by Swanepoel. The absorption co-efficient in the strong absorption region is calculated using the method proposed by Connel and Lewis. Subsequently, both direct and indirect bandgap of the films is estimated from the absorption co-efficient spectrum using Tauc plot. The software codes are written in Python and the graphical user interface is programmed with tkinter package of Python. It provides convenient input and output of the measured and derived data. The software has a feature to cross check the results by retrieving transmission spectrum using the values of refractive index, extinction co-efficient, and thickness obtained from Envelope method. The performance of the software is verified by analyzing numerically generated transmission spectra of a-Si:H amorphous semiconductor thin films, and experimentally measured transmission spectra of electron beam evaporated HfO2 dielectric thin films as examples. PRISA is found to be much simpler and accurate as compared to the other freely available softwares. To help researchers working on thin films, the software is made freely available at https://www.shuvendujena.tk/download.
Cohomological representations of parahoric subgroups
Authors: Chan Charlotte , Ivanov Alexander
Published: January 2021

We give a geometric construction of representations of parahoric subgroups

P
P

of a reductive group

G
G

over a local field which splits over an unramified extension. These representations correspond to characters

θ
\theta

of unramified maximal tori and, when the torus is elliptic, are expected to give rise to supercuspidal representations of

G
G

. We calculate the character of these

P
P

-representations on a special class of regular semisimple elements of

G
G

. Under a certain regularity condition on

θ
\theta

, we prove that the associated

P
P

-representations are irreducible. This generalizes a construction of Lusztig from the hyperspecial case to the setting of an arbitrary parahoric.
lgpr:an interpretable non-parametric method for inferring covariate effects from longitudinal data
Authors: Timonen Juho , Mannerström Henrik , Vehtari Aki , Lähdesmäki Harri
Published: January 2021

Motivation

Longitudinal study designs are indispensable for studying disease progression. Inferring covariate effects from longitudinal data, however, requires interpretable methods that can model complicated covariance structures and detect non-linear effects of both categorical and continuous covariates, as well as their interactions. Detecting disease effects is hindered by the fact that they often occur rapidly near the disease initiation time, and this time point cannot be exactly observed. An additional challenge is that the effect magnitude can be heterogeneous over the subjects.

Results

We present lgpr, a widely applicable and interpretable method for non-parametric analysis of longitudinal data using additive Gaussian processes. We demonstrate that it outperforms previous approaches in identifying the relevant categorical and continuous covariates in various settings. Furthermore, it implements important novel features, including the ability to account for the heterogeneity of covariate effects, their temporal uncertainty, and appropriate observation models for different types of biomedical data. The lgpr tool is implemented as a comprehensive and user-friendly R-package.

Availability and implementation

lgpr is available at jtimonen.github.io/lgpr-usage with documentation, tutorials, test data and code for reproducing the experiments of this article.

Supplementary information

Supplementary data are available at Bioinformatics online.
The Limits of the City: Atmospheres of Lockdown
Authors: Young Alison
Published: January 2021

Criminological engagement with urban environments has burgeoned, including investigations into the criminological sense of place and into the atmospheres of crime and justice. This article analyses cities under lockdown in the 2020 COVID-19 pandemic. Used in numerous cities, lockdowns conjoin public health initiatives and crime control to restrict the location and activities of citizens. Drawing on textual and ethnographic exploration of lockdown in Melbourne, Australia, the article examines how we make meaning in lockdown through processes of sensory and spatial interpretation. Such an approach exposes both atmospheres of control, through the criminalization of everyday activities, and numerous instances of subversion through resistance to and adaptation of the spatial and sensorial characteristics of lockdown. The article argues for the importance of the sensory as a means of conceptualizing, repopulating and redesigning future cities after lockdown ends.
Epidemiology of Invasive Escherichia coli Infection and Antibiotic Resistance Status Among Patients Treated in US Hospitals: 2009–2016
Authors: Begier Elizabeth , Rosenthal Ning A , Gurtman Alejandra , Kartashov Alex , Donald Robert G K , Lockhart Stephen P
Published: January 2021

Background

Published data is limited on the prevalence and risk of recurrence of extraintestinal invasive Escherichia coli infections (IEIs) in the United States.

Methods

The analysis included all inpatient and hospital-based outpatient visits occurring between 2009 and 2016 at hospitals with continuous microbiology data submission to the Premier Healthcare Database for 90 days before and 12 months after the admission or visit. IEI was defined as having positive E. coli culture from a normally sterile site (eg, blood, cerebrospinal fluid). The prevalence of IEI, 12-month risk of recurrent IEI, and antibiotic resistance were assessed.

Results

Overall, 144 944 725 hospital visits among 37 207 510 patients were analyzed, and 71 909 IEI events occurred in 67 583 patients, corresponding to an IEI prevalence of 0.50 events per 1000 visits and 1.82 events per 1000 patients. Recurrence was common: 26.9 per 1000 patients had a recurrent IEI in the 12 months after their infection. Most infections were community acquired (66.4%), and urosepsis was most common clinical syndrome (66.0%). The 30-day risk of IEI among patients undergoing transrectal ultrasound–guided prostate biopsy was high: 5.03 events per 1000 patients. Among all IEI cases with antibiotic susceptibility testing, 9.18% were resistant to extended-spectrum cephalosporins, 28.22% to fluoroquinolones, and 0.14% to carbapenems. Resistance to extended-spectrum cephalosporins increased from 5.46% to 12.97% during the 8-year study period.

Conclusions

This real-world study indicates a substantial burden of IEI and recurrent IEI exists in the United States, as well as increasing resistance to extended-spectrum cephalosporins. Future research should explore risk factors of recurrent IEI aiming to effectively prevent such infections.
The key contribution of platelet and vascular arachidonic acid metabolism to the pathophysiology of atherothrombosis
Authors: Badimon Lina , Vilahur Gemma , Rocca Bianca , Patrono Carlo
Published: January 2021

Arachidonic acid is one of the most abundant and ubiquitous ω-6 polyunsaturated fatty acid, present in esterified form in the membrane phospholipids of all mammalian cells and released from phospholipids by several phospholipases in response to various activating or inhibitory stimuli. Arachidonic acid is the precursor of a large number of enzymatically and non-enzymatically derived, biologically active autacoids, including prostaglandins (PGs), thromboxane (TX) A2, leukotrienes, and epoxyeicosatetraenoic acids (collectively called eicosanoids), endocannabinoids and isoprostanes, respectively. Eicosanoids are local modulators of the physiological functions and pathophysiological roles of blood vessels and platelets. For example, the importance of cyclooxygenase (COX)-1-derived TXA2 from activated platelets in contributing to primary haemostasis and atherothrombosis is demonstrated in animal and human models by the bleeding complications and cardioprotective effects associated with low-dose aspirin, a selective inhibitor of platelet COX-1. The relevance of vascular COX-2-derived prostacyclin (PGI2) in endothelial thromboresistance and atheroprotection is clearly shown by animal and human models and by the adverse cardiovascular effects exerted by COX-2 inhibitors in humans. A vast array of arachidonic acid-transforming enzymes, downstream synthases and isomerases, transmembrane receptors, and specificity in their tissue expression make arachidonic acid metabolism a fine-tuning system of vascular health and disease. Its pharmacological regulation is central in human cardiovascular diseases, as demonstrated by biochemical measurements and intervention trials.
Asymmetric Hapln1a drives regionalized cardiac ECM expansion and promotes heart morphogenesis in zebrafish development
Authors: Derrick Christopher J , Sánchez-Posada Juliana , Hussein Farah , Tessadori Federico , Pollitt Eric J G , Savage Aaron M , Wilkinson Robert N , Chico Timothy J , van Eeden Fredericus J , Bakkers Jeroen , Noël Emily S
Published: January 2021

Aims

Vertebrate heart development requires the complex morphogenesis of a linear tube to form the mature organ, a process essential for correct cardiac form and function, requiring coordination of embryonic laterality, cardiac growth, and regionalized cellular changes. While previous studies have demonstrated broad requirements for extracellular matrix (ECM) components in cardiac morphogenesis, we hypothesized that ECM regionalization may fine tune cardiac shape during heart development.

Methods and results

Using live in vivo light sheet imaging of zebrafish embryos, we describe a left-sided expansion of the ECM between the myocardium and endocardium prior to the onset of heart looping and chamber ballooning. Analysis using an ECM sensor revealed the cardiac ECM is further regionalized along the atrioventricular axis. Spatial transcriptomic analysis of gene expression in the heart tube identified candidate genes that may drive ECM expansion. This approach identified regionalized expression of hapln1a, encoding an ECM cross-linking protein. Validation of transcriptomic data by in situ hybridization confirmed regionalized hapln1a expression in the heart, with highest levels of expression in the future atrium and on the left side of the tube, overlapping with the observed ECM expansion. Analysis of CRISPR-Cas9-generated hapln1a mutants revealed a reduction in atrial size and reduced chamber ballooning. Loss-of-function analysis demonstrated that ECM expansion is dependent upon Hapln1a, together supporting a role for Hapln1a in regionalized ECM modulation and cardiac morphogenesis. Analysis of hapln1a expression in zebrafish mutants with randomized or absent embryonic left–right asymmetry revealed that laterality cues position hapln1a-expressing cells asymmetrically in the left side of the heart tube.

Conclusion

We identify a regionalized ECM expansion in the heart tube which promotes correct heart development, and propose a novel model whereby embryonic laterality cues orient the axis of ECM asymmetry in the heart, suggesting these two pathways interact to promote robust cardiac morphogenesis.
Narratives of Displacement: On Embodied Experience of Migration in Ulitskaya, Lindén, and Palei
Authors: Sorvari Marja
Published: January 2021

This essay discusses representations of migrant experiences of displacement by Russian women writers Liudmila Ulitskaya, Zinaida Lindén, and Marina Palei. The theoretical approach is guided by feminist geography and narrative studies, with attention to the conceptualization of space and place through embodied everyday experiences. The authors represent different writerly positions with which today’s Russophone writers engage, including multilingual and multilocal trends in and outside post-Soviet Russia. Although Lindén and Palei reside outside and Ulitskaya in Russia, their texts address (post-)Soviet migration and displacement, bringing critical perspectives both to their new home countries and to their homeland, Russia. In each text literary figures question and/or oppose the colonizing histories of their homeland and rewrite their personal stories in the form of narratives of displacement.
Modulation of the Gut Microbiota-farnesoid X Receptor Axis Improves Deoxycholic Acid-induced Intestinal Inflammation in Mice
Authors: Xu Mengque , Shen Yuqin , Cen Mengsha , Zhu Yubin , Cheng Fangli , Tang Linlin , Zheng Xia , Kim John J , Dai Ning , Hu Weiling
Published: January 2021

Background and Aims

Inflammatory bowel disease (IBD) is associated with gut dysbiosis and dysregulation of bile acid metabolism. A high luminal content of deoxycholic acid (DCA) with consumption of a Westernised diet is implicated in the pathogenesis of IBD. The aim of the study is to explore the role of intestinal microbiota and bile acid metabolism in mice with DCA-induced intestinal inflammation.

Methods

Wild-type C57BL mice, 4 weeks old, were fed with AIN-93G (control diet), AIN-93G+0.2% DCA, AIN-93G+0.2% DCA+6 weeks of fexaramine (FXR agonist), or AIN-93G+0.2% DCA+antibiotic cocktail, for 24 weeks. Histopathology, western blotting, and qPCR were performed on the intestinal tissue. Faecal microbiota was analysed by 16S rDNA sequencing. Faecal bile acid and short chain fatty acid (SCFA) levels were analysed by chromatography.

Results

Gut dysbiosis and enlarged bile acid pool were observed in DCA-treated mice, accompanied by a lower farnesoid X receptor (FXR) activity in the intestine. Administration of fexaramine mitigated DCA-induced intestinal injury, restored intestinal FXR activity, activated fibroblast growth factor 15, and normalised bile acid metabolism. Furthermore, fexaramine administration increased the abundance of SCFA-producing bacteria. Depletion of the commensal microbiota with antibiotics decreased the diversity of the intestinal microbiota, attenuated bile acid synthesis, and reduced intestinal inflammation induced by DCA.

Conclusions

DCA induced-intestinal inflammation is associated with alterations of gut microbiota and bile acid profiles. Interventions targeting the gut microbiota-FXR signalling pathway may reduce DCA-induced intestinal disease.
Mismatch: a comparative study of vitamin D status in British-Bangladeshi migrants
Authors: Smith Nicholas , Sievert Lynnette Leidy , Muttukrishna Shanthi , Begum Khurshida , Murphy Lorna , Sharmeen Taniya , Gunu Richard , Chowdhury Osul , Bentley Gillian R
Published: January 2021

Background and objectives

Low levels of vitamin D among dark-skinned migrants to northern latitudes and increased risks for associated pathologies illustrate an evolutionary mismatch between an environment of high ultraviolet (UV) radiation to which such migrants are adapted and the low UV environment to which they migrate. Recently, low levels of vitamin D have also been associated with higher risks for contracting COVID-19. South Asians in the UK have higher risk for low vitamin D levels. In this study, we assessed vitamin D status of British-Bangladeshi migrants compared with white British residents and Bangladeshis still living in Bangladesh (‘sedentees’).

Methodology

The cross-sectional study compared serum vitamin D levels among 149 women aged 35–59, comprising British-Bangladeshi migrants (n = 50), white British neighbors (n = 54) and Bangladeshi sedentees (n = 45). Analyses comprised multivariate models to assess serum levels of 25-hydroxyvitamin D (25(OH)D), and associations with anthropometric, lifestyle, health and migration factors.

Results

Vitamin D levels in Bangladeshi migrants were very low: mean 25(OH)D = 32.2 nmol/L ± 13.0, with 29% of migrants classified as deficient (<25 nmol/L) and 94% deficient or insufficient (≤50 nmol/L). Mean levels of vitamin D were significantly lower among British-Bangladeshis compared with Bangladeshi sedentees (50.9 nmol/L ± 13.3, P < 0.001) and were also lower than in white British women (55.3 nmol/L ± 20.9). Lower levels of vitamin D were associated with increased body mass index and low iron status.

Conclusions and implications

We conclude that lower exposure to sunlight in the UK reduces vitamin D levels in Bangladeshi migrants. Recommending supplements could prevent potentially adverse health outcomes associated with vitamin D deficiency.

Lay Summary

Vitamin D deficiency is one example of mismatch between an evolved trait and novel environments. Here we compare vitamin D status of dark-skinned British-Bangladeshi migrants in the UK to Bangladeshis in Bangladesh and white British individuals. Migrants had lower levels of vitamin D and are at risk for associated pathologies.
Alpha 1-adrenoceptor signalling contributes to toxic effects of catecholamine on electrical properties in cardiomyocytes
Authors: Huang Mengying , Fan Xuehui , Yang Zhen , Cyganek Lukas , Li Xin , Yuecel Goekhan , Lan Huan , Li Yingrui , Wendel Angela , Lang Siegfried , Bieback Karen , El-Battrawy Ibrahim , Zhou Xiaobo , Akin Ibrahim , Borggrefe Martin
Published: January 2021

Aims

This study aimed to investigate possible roles and underlying mechanisms of alpha-adrenoceptor coupled signalling for the pathogenesis of Takotsubo syndrome (TTS).

Methods and results

Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were treated with a toxic concentration of epinephrine (Epi, 0.5 mM for 1 h) to mimic the setting of TTS. Patch-clamp technique, polymerase chain reaction (PCR) and Fluorescence-activated cell sorting (FACS) were employed for the study. High concentration Epi suppressed the depolarization velocity, prolonged duration of action potentials and induced arrhythmic events in hiPSC-CMs. The Epi effects were attenuated by an alpha-adrenoceptor blocker (phentolamine), suggesting involvement of alpha-adrenoceptor signalling in arrhythmogenesis related to QT interval prolongation in the setting of TTS. An alpha 1-adrenoceptor agonist (phenylephrine) but not an alpha 2-adrenoceptor agonist (clonidine) mimicked Epi effects. Epi enhanced ROS production, which could be attenuated by the alpha- adrenoceptor blocker. Treatment of cells with H2O2 (100 µM) mimicked the effects of Epi on action potentials and a reactive oxygen species (ROS)-blocker (N-acetyl-I-cysteine, 1 mM) prevented the Epi effects, indicating that the ROS signalling is involved in the alpha-adrenoceptor actions. Nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidases were involved in alpha 1-adrenoceptor signalling. A protein kinase C (PKC) blocker suppressed the effects of Epi, phenylephrine and ROS as well, implying that PKC participated in alpha 1-adrenoceptor signalling and acted as a downstream factor of ROS. The abnormal action potentials resulted from alpha 1-adrenoceptor activation-induced dysfunctions of ion channels including the voltage-dependent Na+ and L-type Ca2+ channels.

Conclusions

Alpha 1-adrenoceptor signalling plays important roles for arrhythmogenesis of TTS. Alpha-adrenoceptor blockers might be clinically helpful for treating arrhythmias in patients with TTS.
Development and external validation of prediction models to predict implantable cardioverter-defibrillator efficacy in primary prevention of sudden cardiac death
Authors: Verstraelen Tom E , van Barreveld Marit , van Dessel Pascal H F M , Boersma Lucas V A , Delnoy Peter-Paul P H M , Tuinenburg Anton E , Theuns Dominic A M J , van der Voort Pepijn H , Kimman Gerardus P , Buskens Erik , Hulleman Michiel , Allaart Cornelis P , Strikwerda Sipke , Scholten Marcoen F , Meine Mathias , Abels René , Maass Alexander H , Firouzi Mehran , Widdershoven Jos W M G , Elders Jan , van Gent Marco W F , Khan Muchtiar , Vernooy Kevin , Grauss Robert W , Tukkie Raymond , van Erven Lieselot , Spierenburg Han A M , Brouwer Marc A , Bartels Gerard L , Bijsterveld Nick R , Borger van der Burg Alida E , Vet Mattheus W , Derksen Richard , Knops Reinoud E , Bracke Frank A L E , Harden Markus , Sticherling Christian , Willems Rik , Friede Tim , Zabel Markus , Dijkgraaf Marcel G W , Zwinderman Aeilko H , Wilde Arthur A M
Published: January 2021

Aims

This study was performed to develop and externally validate prediction models for appropriate implantable cardioverter-defibrillator (ICD) shock and mortality to identify subgroups with insufficient benefit from ICD implantation.

Methods and results

We recruited patients scheduled for primary prevention ICD implantation and reduced left ventricular function. Bootstrapping-based Cox proportional hazards and Fine and Gray competing risk models with likely candidate predictors were developed for all-cause mortality and appropriate ICD shock, respectively. Between 2014 and 2018, we included 1441 consecutive patients in the development and 1450 patients in the validation cohort. During a median follow-up of 2.4 (IQR 2.1–2.8) years, 109 (7.6%) patients received appropriate ICD shock and 193 (13.4%) died in the development cohort. During a median follow-up of 2.7 (IQR 2.0–3.4) years, 105 (7.2%) received appropriate ICD shock and 223 (15.4%) died in the validation cohort. Selected predictors of appropriate ICD shock were gender, NSVT, ACE/ARB use, atrial fibrillation history, Aldosterone-antagonist use, Digoxin use, eGFR, (N)OAC use, and peripheral vascular disease. Selected predictors of all-cause mortality were age, diuretic use, sodium, NT-pro-BNP, and ACE/ARB use. C-statistic was 0.61 and 0.60 at respectively internal and external validation for appropriate ICD shock and 0.74 at both internal and external validation for mortality.

Conclusion

Although this cohort study was specifically designed to develop prediction models, risk stratification still remains challenging and no large group with insufficient benefit of ICD implantation was found. However, the prediction models have some clinical utility as we present several scenarios where ICD implantation might be postponed.
Settlers of our inner surface – factors shaping the gut microbiota from birth to toddlerhood
Authors: Laursen Martin Frederik , Bahl Martin Iain , Licht Tine Rask
Published: January 2021

During the first 3 years of life, the microbial ecosystem within the human gut undergoes a process that is unlike what happens in this ecosystem at any other time of our life. This period in time is considered a highly important developmental window, where the gut microbiota is much less resilient and much more responsive to external and environmental factors than seen in the adult gut. While advanced bioinformatics and clinical correlation studies have received extensive focus within studies of the human microbiome, basic microbial growth physiology has attracted much less attention, although it plays a pivotal role to understand the developing gut microbiota during early life. In this review, we will thus take a microbial ecology perspective on the analysis of factors that influence the temporal development of the infant gut microbiota. Such factors include sources of microbes that seed the intestinal environment, physico-chemical (abiotic) conditions influencing microbial growth and the availability of nutrients needed by the intestinal microbes.
First Complete Genome of the Thermophilic Polyhydroxyalkanoates-Producing Bacterium Schlegelella thermodepolymerans DSM 15344
Authors: Musilova Jana , Kourilova Xenie , Bezdicek Matej , Lengerova Martina , Obruca Stanislav , Skutkova Helena , Sedlar Karel
Published: January 2021

Schlegelella thermodepolymerans is a moderately thermophilic bacterium capable of producing polyhydroxyalkanoates—biodegradable polymers representing an alternative to conventional plastics. Here, we present the first complete genome of the type strain S. thermodepolymerans DSM 15344 that was assembled by hybrid approach using both long (Oxford Nanopore) and short (Illumina) reads. The genome consists of a single 3,858,501-bp-long circular chromosome with GC content of 70.3%. Genome annotation identified 3,650 genes in total, whereas 3,598 open reading frames belonged to protein-coding genes. Functional annotation of the genome and division of genes into clusters of orthologous groups revealed a relatively high number of 1,013 genes with unknown function or unknown clusters of orthologous groups, which reflects the fact that only a little is known about thermophilic polyhydroxyalkanoates-producing bacteria on a genome level. On the other hand, 270 genes involved in energy conversion and production were detected. This group covers genes involved in catabolic processes, which suggests capability of S. thermodepolymerans DSM 15344 to utilize and biotechnologically convert various substrates such as lignocellulose-based saccharides, glycerol, or lipids. Based on the knowledge of its genome, it can be stated that S. thermodepolymerans DSM 15344 is a very interesting, metabolically versatile bacterium with great biotechnological potential.
COMPENSATORY REGULATION OF TWO CLOSELY RELATED HEMOGLOBIN LOCI IN CHIRONOMUS TENTANS
Authors: Thompson Peter , Patel Gordhan
Published: January 2021

Regulatory mutants in the hemoglobin system of Chironomus larvae can be detected by shifts in the relative quantity of specific components among the 10-12 mixed monomers. One such mutant, at or near a hemoglobin structural locus in the right tip of chromosome 3, greatly increases the quantity of that minor hemoglobin and greatly diminishes the quantity of the hemoglobin normally most abundant. Heterozygotes for the mutant are quantitatively intermediate, suggesting a transcriptional basis.—Structural similarities of the two hemoglobins indicate a close evolutionary relationship, and their interdependent but non-coordinate regulation is interpreted as competition for a common factor which functions in transcription. If evolutionary duplication of both structural genes and promotors is assumed, this factor may be a sigma subunit of RNA polymerase which recognizes similar but non-identical promotor regions. Parallels in the compensatory control of human hemoglobins are described.
RNA SYNTHESIS AND HETEROCHROMATIZATION IN EARLY DEVELOPMENT OF A MEALYBUG
Authors: Sabour Mohammad
Published: January 2021

Microinjection of specific radioisotope tracers showed that DNA and protein synthesis are triggered by fertilization but nuclear RNA synthesis does not occur until the cleavage nuclei migrate to the periphery. In the male, heterochromatization of the paternal chromosome set also occurs when the cleavage nuclei reach the periphery. These results help to explain those of several types of genetic test, especially the failure of typical dominant lethal induction in the heterochromatized set.
THE LOCATION OF VIABILITY GENES WITHIN A TESTCROSS FRAMEWORK
Authors: Chapco William
Published: January 2021

The maximum likelihood method is applied to the problem of estimating the positions and effects of viability genes. Whenever testcross linkage data indicate the presence of differential viability, it is hypothesized that there exists one viability gene between each marker. Estimation is possible only for two-point data since the number of independent expectation expressions is less than the number of parameters for three or more markers. It is pointed out that within the two-point testcross system, it is impossible to distinguish between pleiotropic effects of the marker genes and the effect of a middle viability gene, if existent. The methods outlined will be useful in their application to experiments specifically designed to locate induced viability genes.
A STUDY OF SPONTANEOUS MUTATION RATES AT TEN LOCI DETECTABLE BY STARCH GEL ELECTROPHORESIS IN DROSOPHILA MELANOGASTER
Authors: Tobari Yoshiko N , Kojima Ken-Ichi
Published: January 2021

Spontaneous mutation rates at ten allozyme loci on chromosomes II and III of Drosophila melanogaster were studied. Over the three and a half years study, one α-GPD mutation and two different IDH mutations were obtained. The α-GPD mutation was inherited in the Mendelian fashion, as expected. The two IDH mutations were peculiar in that the band of new types appeared only in females. In males, only the original bands were stained, and the positions where mutant alleles' bands should be present were blank. Both IDH mutant homozygotes appeared as null allele homozygotes, while in females clear-cut single bands were present.—The rates of spontaneous mutation varied greatly. Eight loci studied (MDH, ADH, EST-6, APH, EST-C, ODH, XDH, AO) did not give any germ-line mutation. The average germ-line mutation rate over all ten loci was estimated at 4.5 × 10-6. This rate is considerably smaller than that for sex-linked recessive visible mutations (Muller, Valencia and Valencia 1950), but it is somewhat less than autosomal recessive visible mutations (Glass and Ritterhoff 1956).
THE ADDITION OF LAC+ CHROMOSOME FRAGMENTS TO THE E. COLI PROA—PROB—LAC DELETION XIII CHROMOSOME
Authors: Stodolsky M , Rae M Engel , Mullenbach E
Published: January 2021

Escherichia coli with the proA–proB–lac deletion ×111 (Δ111) can be transduced with bacteriophage P1 propagated on a wild-type lac  + donor. Though the donor lac  + genes cannot be integrated by replacement of the recipient Δ111 marker, the transduction process has the characteristics generally associated with generalized transduction of bacterial genes. Transduction does not require P1 helper infection, is stimulated by UV irradiation of transducing particles, and does require homology between the donor lac  + chromosome and the recipient Δ111 chromosome. Among transductants produced through multiple P1 infection, a minority of P1 dl lysogens are present. But the majority of the transductants have unstable lac  + units, designated lac V, which are without detected P1 gene content. LacV is tightly linked to the Δ111 locus. Instability of lac  + is eliminated when a recombination deficiency is introduced through a substitution of recA1 for rec  +. The properties of the Δ111/lacV strains are attributable to a chromosome in which lac  + is situated between units of a genetic duplication beside the Δ111 locus. To explain the formation of partially diploid chromosomes we suggest that chromosome fragment integration is sometimes accomplished through a single aberrant recombination, a fusion of genetically heterologous DNA ends, and a single legitimate crossover.
FACTORS AFFECTING RECOGNITION AND DISJUNCTION OF CHROMOSOMES AT DISTRIBUTIVE PAIRING IN FEMALE DROSOPHILA MELANOGASTER. I. TOTAL LENGTH VS. ARM LENGTH
Authors: Moore Charleen M , Grell Rhoda F
Published: January 2021

The behavior of a compound metacentric fourth chromosome (see PDF) has been examined to determine whether arm length or total length is the basis for recognition in distributive pairing. Recognition was judged by the frequency with which the (see PDF) nondisjoined from a series of X duplications (Dp), ranging in size from ≤ 0.3 to > 4 times the size of a single fourth chromosome. Dp, (see PDF) nondisjunction was measured in the absence and in the presence of a competitor, a compound metacentric X. In both situations, total length and not arm length, was found to confer the characteristic recognition property to the (see PDF). A comparison of Dp, (see PDF) nondisjunction curves for both the noncompetitive and competitive situations with analogous Dp, 4 curves previously obtained, show the Dp, (see PDF) curves to be similar in shape to those obtained earlier but displaced one unit to the right, corresponding precisely to the difference in size between the (see PDF) and the 4. Rules governing chromosome recognition for acrocentrics were found completely applicable to metacentrics; disjunctive behavior of metacentrics differed from that of acrocentrics in that two arms conferred on a chromosome the capacity to act as the intermediate of a trivalent when size no longer warranted this attribute. This capacity, itself, is size-dependent.
POPULATION GENETICS OF LEBISTES (POECILIA) RETICULATUS PETERS (POECILIIDAE; PISCES). I. EFFECTS OF RADIATION-INDUCED MUTATIONS ON THE SEGREGATION RATIO IN POSTIRRADIATION F2
Authors: Schröder Johannes Horst , Holzberg Sebastian
Published: January 2021

Wild-type germ cells of the viviparous fish, Lebistes (Poecilia) reticulatus, were irradiated in the stages of oogonia, spermatogonia or spermatozoa with 1000 R of X rays at a dose-rate of 200–220 R/min. The grown-up fish were mated after irradiation or sham treatment to unirradiated mutant fish homozygous for three recessive gene loci, causing albinism, lack of yellow and reddish pigmentation ("blue" constitution), and diminution of the size of melanophores ("blond" constitution). As compared to the control series, the phenotypic segregation ratios in the adult F2 generation after irradiation was changed significantly in favour of wild-type and blue fish, whereas the proportion of albinotic, blond and "white" (= blond + blue) guppies was lowered. This unidirectional effect in postirradiation F2 was greatest after exposure of spermatozoa with 2 × 500 R (24 hr apart), followed by single doses of 1000 R to spermatogonia and oogonia. These results were explained in terms of a synergistic interaction of recessive radiation-induced mutations in the heterozygous state with those genotypes of the guppy which affect the formation of melanophoric patterns and the synthesis of melanins.
CHROMOSOME PAIRING IN MAIZE
Authors: Burnham Charles R , Stout John T , Weinheimer William H , Kowles Richard V , Phillips Ronald L
Published: January 2021

This report summarizes our observations at pachytene on opposite-arms intercrosses between stocks of interchanges that involve chromosomes 1 and 5 in maize.—Pairing does not begin at the centromeres in these intercrosses.—We propose a model which assumes different probability values along each chromosome arm for the initial or primary site of pairing. Observations on the frequencies of the different types of configurations at pachytene were used to estimate probability values which satisfactorily fit the data.—There is a relatively low probability (of the order of.1 to.3) for the initial pairing to be in a short terminal segment (about.1 of the arm length). Initial pairing in the one or two short segments adjacent to the tip segment is much higher. Initial pairing is much lower in segments successively closer to the middles of the chromosome arms, and then zero or nearly zero in the proximal half of the arm. This means that the initial pairing may fail occasionally even in a relatively long interchanged segment and produce a T-shaped (3-armed) configuration.—After the initial pairing has occurred, the average probability that a secondary site of pairing is adjacent to the centromere in a segment.3 to.4 the length of an arm is low (.13, ranging from.02 to.29).—We can predict that in an intercross in which both breakpoints in both parental interchanges are far out on the chromosomes, "pairs" will be formed with nonhomologous ends (homologous differential segments paired). In these pairing could have begun at any point in the interstitial segments, but not likely in segments close to the centromeres.—Multiple secondary sites which vary in time or in order of pairing will explain the variation in position of the cross-shaped pachytene configuration in interchange heterozygotes.—The observed configuration in any one cell is the result of a particular combination of pairing events at the various sites. This is a very different concept of pairing from previous interpretations which described it as a result of zipper-like action, and the variation in position of the pachytene cross-configuration as the result of "shifts" in position.—Our cytogenetic results and their interpretation are in close agreement with reports on chromosome ultrastructure and molecular events in the early stages of meiosis, i.e. the attachment of chromosome ends to the nuclear membrane, the manner in which synaptonemal complexes develop, and the regions of DNA whose replication is delayed until zygonema.