bluuebunny/crossref_metadata_2025 huggingface dataset:
Construction of conductive and biocompatible three-dimensional nickel scaffolds with electrodeposited chitosan for nerve regeneration
Authors: Liu Zhepeng , Wang Kewu , Luo Yawen , Ou Chenyan , Xia Yan , Liang Wenli , Zhang Xiaoshi , Tian Geng
Published: April 2021

In this study, construction of conductive and biocompatible three-dimensional nickel scaffolds (NiF) with electrodeposited chitosan (CS) for tissue engineering. The scaffolds were characterized by scanning electron microscopy (SEM), mechanical testing, water absorption, retention capacity and conductive sensitivity. Three-dimensional nickel scaffolds with electrodeposited chitosan (NiFC-n) exhibited uniformly filling structure on their surfaces and the inner structure and good mechanical property. When the versatile NiFC-n sensors were attached to different deformation, they could detect a variety of motion signals. MTT assay, Cells were stained with carboxyfluoresceinsuccinimidyl ester (CFSE) assay, apoptosis experiment and cell culture experiment results showed that NiFCn had good biocompatibility. The results indicated that the NiFC2 had a low immunogenicity, and can promote cell proliferation and support cell adhesion. This work provides a safe and feasible electrodeposition method to construct conductive and biocompatible three-dimensional nickel scaffolds with electrodeposited chitosan for tissue engineering. Therefore, NiFCn had potential application as biomaterials that may contact with real time measurement of rehabilitation for tissue engineering.
Reinforcing effects of cyclic expansion extrusion with an asymmetrical extrusion cavity (CEE-AEC) on pure magnesium
Authors: Ji JinSheng , Zheng Jie , Shi YuSha , Zhang Heng , Zhang ZhiMin , Xue Yong
Published: April 2021

In this paper, a relatively novel severe plastic deformation method cyclic expansion extrusionwith an asymmetrical extrusioncavity (CEE-AEC) was carried out to prepare large-sized pure magnesium (Mg) with high comprehensive performance. Finite element analysis (FEM) was used to study the plastic deformation process and Electron Back-Scattered Diffraction (EBSD) was aimed to research the microstructural evolution. Three passes and isothermal deformation at 250 °C were chosen to satisfy the research. The central part of the billet was cut as the research area, and the resultant microstructure and mechanical properties were analyzed systematically. The results showed that the grain size was remarkably refined due to continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX). Twins participated in the progress of deformation. The shear strain introduced by the asymmetrical extrusion cavity determined the formation of inclined basal texture, leading to the increasing value of basal 〈a〉 slip system Schmid factor. The best comprehensive tensile properties were obtained after three passes of deformation, and the contributions came from grain refinement strengthening and texture modification, respectively.
The enhanced aerosol deposition by bipolar corona discharge arrays
Authors: LI Jiacheng , HUANG Zhongzheng , LIU Dawei , ZHENG Kuanlei
Published: April 2021

The corona discharges provide an efficient way to induce precipitation or eliminate fog by increasing ion density in the open air. In this paper, one bipolar corona discharge array (positive and negative high voltage coupled simultaneously) which can generate high densities of positive and negative ions is developed. The comparison between bipolar corona discharge array and unipolar corona discharge array (positive or negative coupled only) indicates that bipolar corona discharge array can generate ∼3 times higher ion density than unipolar corona discharge array. More charged aerosols are produced through collisions between ions and aerosols. The collision rate between aerosols is increased substantially by the attractive forces between positively and negatively charged aerosols. The deposition of aerosols induced by bipolar discharges is 25.7% higher than that of unipolar discharges at the humidity super-saturation condition. Therefore, the bipolar corona discharge system is a new option for the large scale ion sources used for artificial weather modification.
Observation of the perturbed eigenvalues of PT-symmetric LC resonator systems
Authors: Zhou Bin-Bin , Wang Li-Feng , Dong Lei , Huang Qing-An
Published: April 2021

We address both theoretically and experimentally the influence of asymmetric perturbation on the eigenvalues of parity-time (PT) symmetric resonator systems under the symmetric gain-loss arrangement, based on an inductively coupled inductor-capacitor-resistor (LCR) pair. The perturbed eigenvalues have been theoretically presented, numerically simulated, and experimentally measured. It shows that the asymmetric perturbation breaks PT-symmetry, leading to complex eigenvalues, which is different from the broken PT-symmetric phase with complex-conjugate eigenvalues. We have analyzed the perturbed frequency responses in all phases. At the exceptional points (EP), the resulting eigenvalues splitting is proportional to the square root of perturbation, showing the advantage of being highly sensitive to asymmetric perturbation. Meanwhile, the smaller the perturbation, the higher the sensitivity. The perturbation effect of PT-symmetric systems may be utilized to detect small signal changes in LC passive wireless sensors.
Characterising industrial thermal plumes in coastal regions using 3-D numerical simulations
Authors: Faulkner Agnieszka , Bulgin Claire E , Merchant Christopher J
Published: April 2021

Coastal power stations use sea water as a coolant, releasing it back into coastal environments at a higher-than-ambient temperature. Due to the possible ecological impacts on sensitive coastal zones, thermal plume formed by warmer coolant waters needs to be monitored, which is typically done through field campaigns. This paper assesses the use of simulations and remotely sensed observations as complimentary methods to characterise plume behaviour for a chosen coastal power station located within an inter-tidal embayment. Simulations of the thermal plume for two main tide phases and associated sea current conditions are validated against the high-resolution satellite observations. Simulated plume temperatures are higher than the observed values, with the biggest difference of 2 °C. The direction of the simulated plume dispersion is in agreement with observations and depends on the strength and direction of sea currents associated with the phase of the tide. The plume stretches most at the surface with limited impact on the benthic temperatures.
Electronic states and metallic character of carbide Co/MoS2 catalytic interface
Authors: López-Galán Oscar A , Ramos Manuel , Berhault Gilles , Torres Brenda , Chianelli Russell R
Published: April 2021

We report computer assisted density functional theory computations of electronic states in carbide Co9S8/MoS2 interface model. The interface model was previously proposed using crystallographic information from experimental high-resolution TEM observations; and directly observed by in-situ heating to confirm carbon deposit occurs at the sulfur edge of Co9S8/MoS2 which creates a thin carbide layer. In here, the total energy for carbon adsorption results eight times more favorable to occur at sulfur edge in comparison to molybdenum or cobalt replacement by permutation of carbon atoms as contained in C, CH, CH2 species by exothermic energies. Amorphous carbon excites 2
pz
orbitals as observed on density of states near Fermi level (F

E
), and 13% decreased in terms of charge carriers available, causing to decrease its chemical catalytic reactivity and bending of MoS2 slabs as carbon starts to accumulate at the sulfur edge mainly, which is attributed to charge distribution around the adsorption site caused by the foreign atoms, confirmed by electron density plots, that acts as ‘electron traps’. This helps us concluding that carbon replacement can induce change of selectivity in direct desulfurization pathway.
Microstructure and anti-corrosion properties of spray pyrolyzed Ni-doped ZnO thin films for multifunctional surface protection applications
Authors: Owoeye Victor Adewale , Ajenifuja Emmanuel , Adeoye Abiodun Eyitayo , Salau Ayodeji Olalekan , Akindadelo Adedeji Tomide , Pelemo David A , Idowu Popoola Abimbola Patricia
Published: April 2021

The microstructures, electrochemical, and hardness properties of deposited Ni-doped ZnO thin films on ultrasonically cleaned 316L stainless steel (316L ST) employing a low-cost chemical spray pyrolysis technique (CSPT) was examined in this work. The films were prepared at various concentrations using commercially available purity zinc acetate and nickel acetate as the precursor sources. The result of x-ray diffractometry (XRD) showed that the films have polycrystalline structure with all the films consisting of single phase ZnO hexagonal wurtzite structure. Scanning electron microscopy (SEM) result affirmed that the coated films adhered to the substrates and equally spread through the substrate surfaces. The surface microstructure of the 316L ST improves with Ni content. The corrosion resistance of the 316L ST was observed to improve with the coated films. Hardness value of the uncoated 316L ST was observed to increase from 139.15 HV to 233.03 HV of coated S3 (9% nickel acetate (0.2 M) and 91% zinc acetate (0.2 M)).
Developing a virtual geriatric perioperative medicine clinic: a mixed methods healthcare improvement study
Authors: Joughin Andrea , Ibitoye Sarah , Crees Amy , Shipway David , Braude Philip
Published: April 2021

Background

the Geriatric Perioperative Care clinic at North Bristol NHS Trust was suspended in March 2020 during the COVID-19 pandemic. A virtual clinic was piloted to deliver preoperative health optimisation and shared decision-making for patients undergoing critical elective surgery. No literature existed on virtual preoperative clinics for older people to support the development.

Objective

this healthcare improvement study describes the setup and delivery of the virtual clinic as its primary aim. Secondary aims included: assessing older people’s access to technology and their digital literacy for virtual consultation; to describe barriers and facilitators for consultations, as well as evaluation of patient and clinician satisfaction with the consultations' mode of delivery and outcomes.

Methods

a mixed methods healthcare improvement study was undertaken through plan-do-study-act cycles, semi-structure interviews, and quantitative service benchmarking.

Results

the pilot evaluated 67 preoperative consultations (43.3% video, 56.7% telephone, mean age 75) with a mix of surgical pathology (vascular 88.1%, colorectal 10.4%, urological 1.5%). Patient feedback demonstrated improved understanding of conditions (90.6%), and adequate opportunity to express opinions and questions (96.2%). Clinicians preferred video consultations (adequate to deliver services: 89.7% video; 68.4% telephone). The greatest barriers to engagement, none of which were exclusions to participation, included cognitive impairment, sensory impairment, or needing technical assistance setting up video consultations (52.2%).

Conclusions

delivering a virtual preoperative medical optimisation and shared decision clinic for older people is feasible. This study will aid other units in developing their own virtual preoperative clinics. Future work should evaluate perioperative outcomes of delivering a face-to-face versus virtual clinic.
P39 Cross sectional survey of medical student volunteering and education during the coronavirus pandemic in the United Kingdom
Authors:   MedEd Collaborative (Steering Group, Byrne Matthew H V , Ashcroft James , Alexander Laith , Wan Jonathan , Harvey Anna , Clelland Andrew , Schindler Nick , Brassett Cecilia ,   Survey Development Group, Vance Gillian , Burford Bryan , Raj Vigneshwar , Brown Anmol Arora Megan E L , Bandyopadhyay Soham , Dominic Catherine , Dawidziuk Siena Hayes Aleksander , Kinder Florence , Sravanam Sanskrithi , Kawka Michal , Vaughan Adam
Published: April 2021

Introduction

COVID-19 led to global disruption of healthcare and many students volunteered to provide clinical support. Volunteering to work was a unique medical education opportunity; however, it is unknown whether this was a positive learning experience.

Methods

The COVID Ready 2 study is a national cross-sectional study of all medical students at UK medical schools. We will compare opinions of those who did and did not volunteer to determine the educational benefit and issues they faced. We will use thematic analysis to identify themes in qualitative responses, in addition to quantitative analysis.

Results

The primary objective is to explore the effect of volunteering during the pandemic on medical education in comparison to those who did not volunteer. Our secondary objectives are to identify: whether students would be willing to assume similar roles in a non-pandemic setting; if students found the experience more or less beneficial than traditional hospital placements and reasons for this; what the perceived benefits and disadvantages of volunteering were; the difference in perceived preparedness between students who did and did not volunteer for foundation training year one and the next academic year; training received by volunteers; and to explore issues associated with volunteering, including safety issues and issues with role and competence.

Conclusions

We anticipate this study will help identify volunteer structures that have been beneficial for students, so that similar infrastructures can be used in the future; and help determine whether formal voluntary roles should be introduced into the non-pandemic medical curriculum.
VPS34 suppression reverses osimertinib resistance via simultaneously inhibiting glycolysis and autophagy
Authors: Chen Hengyi , Lu Conghua , Lin Caiyu , Li Li , Wang Yubo , Han Rui , Hu Chen , He Yong
Published: April 2021

Autophagy and glycolysis are associated with osimertinib resistance. The energy complement and dynamic balance between these two processes make it difficult to block the process of drug resistance; breaking the complementary relationship between them may effectively overcome drug resistance. However, the exact mechanisms and the key players for regulating autophagy and glycolysis remain unclear. In this study, we demonstrate that autophagy and glycolysis levels in osimertinib-resistant cells were markedly higher than parental cells, and a dynamic balance existed between them. Inhibition of the class III phosphoinositide 3-kinase vacuolar protein sorting 34 (VPS34) with 3-methyladenine or small interfering RNA can not only inhibit abnormally enhanced autophagy but also inhibit glycolysis by inhibiting the location of epidermal growth factor receptor (EGFR) and the expression of hexokinase II. By demonstrating that VPS34 is the key player controlling autophagy and glycolysis simultaneously, our study may provide a new strategy for overcoming osimertinib resistance for treatment of EGFR-mutant non-small cell lung cancer patients.
THE ACTION OF HOMOTHALLISM GENES IN SACCHAROMYCES DIPLOIDS DURING VEGETATIVE GROWTH AND THE EQUIVALENCE OF hm
a and HMα LOCI FUNCTIONS
Authors: Klar Amar J S , Fogel Seymour
Published: April 2021

The action of homothallism genes in vegetatively growing diploid cells was examined. The results demonstrate that homothallism genes function during regular vegetative growth cycles as well as during the first few divisions after spore germination. A procedure based on ultraviolet-induced reciprocal mitotic recombination monitored by homozygosity for cryptopleurine resistance (a recessive marker closely linked to the mating-type locus) allowed us to identify and recover Saccharomyces cerevisiae colonies sectored for the mating-type locus i.e., a/a and α/α. Homothallism genes can switch a/a or α/α vegetative diploid cells, generated from a strain with genotype a/α HO/ho HMα/HMα HM  a/HM  a, to a/α diploids or a/a/α/α tetraploids during a given mitotic division cycle. We found that both a/a and α/α sectors generated from a strain with genotype a/α HO/HO hmα/hmα hm  a/HM  a switch to a/α diploids or a/a/α/α tetraploids. This finding supports Naumov and Tolstorukov's suggestion (1973) that the hm  a allele provides for the same functions as the HMα allele, namely, a switch at the mating-type locus from α to a. The HO allele is dominant to ho but hm  a and HM  a alleles are codominant. A loose linkage between the mating-type and the HMα loci (∼55cM), confirming Harashima, Nogi and Oshima (1974) data, was observed.
NEW MUTATIONS AND A 7-CHROMOSOME LINKAGE MAP OF SCHIZOPHYLLUM COMMUNE
Authors: Frankel Carl , Ellingboe Albert H
Published: April 2021

Forty-eight useful new mutations of S. commune were obtained by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. Their requirements and meiotic linkage relationships to each other and previously mapped areas were investigated. Several of these new mutations were incorporated into diploid strains so that the diploids contained at least one marker on every linkage group. Analysis of somatic recombination in these diploids indicated that each meiotic linkage group corresponded to an independent chromosome.
THE INSTABILITY OF NEUROSPORA DUPLICATION Dp(IL⇒IR)H4250, AND ITS GENETIC CONTROL
Authors: Newmeyer Dorothy , Galeazzi Donna R
Published: April 2021

Previous work (Newmeyer and Taylor 1967) showed that a nontandem duplication, Dp(IL→IR)H4250, is regularly produced by recombination in crosses heterozygous for the effectively terminal pericentric inversion In(IL→IR)H4250. The duplications initially have strongly inhibited growth because they are heterozygous for mating type, which behaves like a vegetative-incompatibility (het) locus. Such cultures "escape" from the inhibition as a result of events that eliminate the mating-type heterozygosity. The product of a given escape event may be barren or fertile. (Neurospora duplications are characteristically barren; that is, when crossed, they make many perithecia but few ascospores.)—The present paper reports on a genetic analysis of the instability of Dp(IL→IR)H4250 . Most of the barren escape products behave as if due either to mitotic crossovers, which make mating type and distal markers homozygous, or to very long deletions which uncover mating type and all distal markers; presumably the latter would retain enough duplicated material to render them barren. It is difficult to distinguish between these two possibilities, but homozygosis seems more probable and has been clearly demonstrated in one case. Only a few barren escapes could be due to short deletions or to changes at the mating-type locus.—The fertile escape products appear to be euploid. Most of these behave as if they arose by precise deletion of one or the other duplicated segment, thus restoring one of the parental sequences. A large majority of the precise deletions restore normal sequence; only a few restore inversion sequence. Preferential restoration of the normal sequence has also been found by other workers for Neurospora duplications from several other rearrangements. A hypothesis is presented to explain these findings; it is posulated that the precise deletions result from mitotic crossing over in homologous material located at chromosome tips and tip-break-points.—There is a smaller group of fertile escapes that are unlike either parental sequence; at least one of these involves a chromosome break outside the duplicated region.—Duplications in which the vegetative incompatibility is suppressed by the unlinked modifier tol are extremely barren; they only rarely lose a duplicated segment so as to become fertile.—The instability of Dp(IL→IR)H4250, with and without tol, is markedly altered by factors in the genetic background. The two factors studied in detail have qualitatively different effects.
GENETIC ANALYSIS OF A STRAIN OF MICE PLATEAUED FOR LITTER SIZE
Authors: Eklund J , Bradford G E
Published: April 2021

A strain of mice (S1) was successfully selected for large litter size for 31 generations, increasing the mean by 4.2 young per litter. After generation 31, there was no further progress and it was concluded that a selection plateau had been reached. Realized heritability decreased during the course of the experiment from 0.16 ± 0.06 for the first 15 generations to 0.00 ± 0.03 for generations 30 through 45. — In order to explore the nature of the selection plateau, the following groups were derived from line S1 at generation 34 or 35: Upward selection with inbreeding (SF), random (relaxed) selection (SO), and downward selection (SR). Selections were carried out for 10 or 11 generations. The means of SO and SF were similar to those of S1, ruling out any major effect of natural selection or overdominance. SR decreased, the mean averaging 2.3 young per litter below that of S1 during the last three generations. The fact that SR responded to selection indicates that genetic variance was still present in the plateaued population. The SF sublines were crossed when the inbreeding was 95% and a new line, SX, was formed. SX was maintained for three generations and the difference of +0.7 young per litter above the contemporary generations of S1 was significant. The results from this experiment suggest that the selection plateau in line S1 was caused by reduction of additive genetic variance to a very low level. Some nonadditive genetic variance remained, however, and was attributed to recessive alleles at low frequency. In agreement with results reported by Falconer (1971), inbreeding with selection followed by crossing of the inbred sublines proved to be effective in overcoming a selection plateau in litter size.
A MUTATION THAT PERMITS THE EXPRESSION OF NORMALLY SILENT COPIES OF MATING-TYPE INFORMATION IN SACCHAROMYCES CEREVISIAE
Authors: Haber James E , George Jeanne P
Published: April 2021

Studies of heterothallic and homothallic strains of Saccharomyces cerevisiae have led to the suggestion that mating-type information is located at three distinct sites on chromosome 3, although only information at the mating-type (MAT) locus is expressed (HICKS, STRATHERN and HERSKO-WITZ, 1977). We have found that the recessive mutation cmt permits expression of the normally silent copies of mating-type information at the HMa and HMα loci. In haploid strains carrying HMa and HMα, the cmt mutation allows the simultaneous expression of both a and a information, leading to a nonmating ("MATa/MATα") phenotype. The effects of cmt can be masked by changing the mating-type information at HMa or HMα. For example, a cell of genotype MATα hma HMα  cmt has an a mating type, while a MATα  hma HMα cmt strain is nonmating. Expression of mating-type information at the HM loci can correct the mating and sporulation defects of the mata* and matα10 alleles. Meiotic segregants recovered from cmt/cmt diploids carrying the mat mutations demonstrate that these mutants are not "healed" to normal MAT alleles, as is the case in parallel studies using the homothallism gene H0.—All of the results are consistent with the notion that the HMa and hmα alleles both code for α information, while HMα and hma both code for a information. The cmt mutation demonstrates that these normally silent copies of mating-type and sporulation information can be expressed and that the information at these loci is functionally equivalent to that found at MAT. The cmt mutation does not cause interconversions of mating-type alleles at MAT, and it is not genetically linked to MAT, HMa, HMα or HO. In cmt heterozygotes, cmt becomes homozygous at a frequency greater than 1% when the genotype at the MAT locus is mata*/MATα or matα10/MATa,
ORGANIZATION OF THE RUDIMENTARY WING LOCUS IN DROSOPHILA MELANOGASTER. I. THE ISOLATION AND PARTIAL CHARACTERIZATION OF MUTANTS INDUCED WITH ETHYL METHANESULFONATE, ICR–170 AND X RAYS
Authors: Rawls John M , Porter Lawrence A
Published: April 2021

New rudimentary (r) mutants have been isolated following mutagenesis with ethyl methanesulfonate (rLE), ICR-170 (rLI) and X rays (rLX) . From wing phenotype measurements on hamoallelic females, it has been shown that the rLE mutant series includes several leaky alleles, as well as alleles that produce moderate and strong r phenotypes. All of the tested rLI alleles yielded strong r phenotypes in homoallelic females, whereas the rLX series was found to include both moderate and strong alleles. Based on allele complementation for the wing phenotype, it was found that all three mutant series include both complementing and noncomplementing alleles, but the relative frequencies of these two types of alleles differ considerably among the three series. Complementing alleles comprise most of the rLE mutant series (19 of 25) and almost one-half of the rLX series (five of 12), while only one of 16 rLI mutants is a complementing allele. Data from enzyme assays of mutants mostly support the direct correlation of genetic complementation units with the activities of the first three enzymes in the de novo pyrimidine biosynthetic pathway. All of these findings are discussed in light of evidence that these three enzymes are contained within a tri-enzyme complex in animals. We conclude that the available genetic evidence supports the contention that the trienzyme complex is encoded by a single mRNA.
MAR1—A REGULATOR OF THE HM
a AND HMα LOCI IN SACCHAROMYCES CEREVISIAE
Authors: Klar Amar J S , Fogel Seymour , Macleod Kathy
Published: April 2021

A mutation in the MAR1 (mating-type regulator) locus causing sterility in Saccharomyces cerevisiae is reported. The mutation maps on the left arm of linkage group IV between trp1 and cdc2 at a distance of about 27 CM from trp1 and about 31 cM from cdc2. Haploid strains with genotype MATα HMα HMa  mar1-1 and MATa HMα HMa mar1-1 are sterile. However, MATα hmα HMa mar1-1 and MATa HMα hma mar1-1 strains exhibit a and a mating type, respectively. The sterile strains can be "rare mated" with standard strains as a consequence of mutational changes at HMa and HMα. It is proposed that the MAR1 locus blocks the expression of MATα and MATa information thought to exist at HMa and HMα loci, respectively (HICKS, STRATHERN and HERSKOWITZ, 1977). In a mar1-1 mutant, the expression of both HMα and HMa information leads to a nonmating phenotype similar to that of MATa/MATα diploids. The genetic evidence reported here is consistent with a central feature of the "cassette model", namely that HMα and hma carry MATa information and HMa and hmα carry MATα information.
CYTOGENETIC ANALYSIS OF AN SD CHROMOSOME FROM A NATURAL POPULATION OF DROSOPHILA MELANOGASTER
Authors: Trippa G , Loverre A , Cicchetti R
Published: April 2021

The discovery and the cytogenetic characterization of a new SD(Segregation Distorter) chromosome 2 from a natural population in Ranna (Sicily, Italy), SDRa, are reported. The main features of this chromosome are as follows: (a) it contains an SdRa gene with a moderate degree of segregation distortion (= 0.72), (b) a recessive female sterile gene, fs(2)TLM, responsible for modifications of the morphology and structure of the testes and ovaries is located at 89.7, (c) SDRa/SDRa males and females are viable but sterile, the females due to homozygosis of fs(2)TLM and the males because of homozygosis of a region containing the Sd locus, and (d) SDi/SDj combinations are fertile, thus suggesting that the different Sd factors found in natural populations constitute a multiple allelic series.——These data may indicate that each population containing SD chromosomes has evolved its own genetic architecture for the complex SD system, with specific modifiers and perhaps different Sd genes. The possibility of reconstructing the evolutionary pattern of the SDRa chromosome in the natural Ranna population after the model of CHARLESWORTH and HARTL (1978) and CROW (1979) is considered.
HETEROCHROMATIC RECOMBINATION IN GERM CELLS OF DROSOPHILA MELANOGASTER FEMALES
Authors: Hiraizumi Yuichiro
Published: April 2021

Heterochromatic recombination in germ cells was found to occur in females of Drosophila melanogaster having a specific genotype. Results of the present study can be summarized as follows: (1) The frequency of heterochromatic recombination descreases consistently and markedly as the female ages. (2) The female that induces heterochromatic recombination is associated with reduced number of progeny when she is young, but as she gets older, the number of progeny increases, approaching that of the normal female. The reduction in the number of progeny is due to unhatchability of eggs produced, not to reduced egg laying. (3) Cytoplasmic factors affect the above two traits. These traits seem to be due to interaction between chromosomal and cytoplasmic elements. (4) These traits are not expressed in males. (5) The increase in recombination frequency seems to be limited to the centric heterochromatin.—It is suggested that heterochromatic recombination is one of the traits associated with the I-R system of hybrid dysgenesis in D. melanogaster.
GENIC VARIATION IN MALE HAPLOIDS UNDER DETERMINISTIC SELECTION
Authors: Pamilo P , Crozier R H
Published: April 2021

Genic variation in male haploids and male diploids was compared assuming constant fitnesses (derived from computer-generated random numbers) and infinite population size. Several models were studied, differing by the fitness correlation between the sexes (rs) and genotypes (rg), and by the intensity of selection as measured by the coefficient of variation (CV) of the fitness distribution. Genic variation was quantified using the proportion of polymorphic loci, P, the gene diversity at polymorphic loci, Hp, and the gene diversity over all loci, Ha. The two genetic systems were compared via variation ratios: variation in male haploidy/variation in male diploidy.—P and Ha were markedly lower for male-haploids than for male diploids, the variation ratios declining with increasing rs, rg and CV, but the two genetic systems were similar for Hp. Except for male diploids with rs = 1, the two sexes had different equilibrium gene frequencies but the sample sizes required to detect such differences reliably were larger than usually possible in surveys of natural populations.—Data from natural populations fit the above trends qualitatively, but the variation ratios are much lower than those from our analyses, except that for Hp, which is higher when Drosophila is excluded. Also, the frequency distribution of most common alleles from electrophoretic data has a deficiency of intermediate frequencies compared to that from the computer-generated sets of fitnesses, possibly reflecting either the influence of stochastic processes shifting frequencies away from equilibrium or the involvement of alleles under selection-mutation balance.——While electrophoretic data suggest that Drosophila has unusually high levels of genic variation, unusually low levels of genic variation in male haploids compared with male diploids are not strongly indicated. However, if further data confirm male haploids as having low levels of genic variation, likely explanations are that the bulk of electrophoretically detected variation involves fixed-fitness balancing selection, selection-mutation balance involving slightly deleterious recessive alleles, new favorable male haploid alleles moving more rapidly to fixation than under male diploidy and thus carrying linked loci to fixation faster, or some combination of these possible factors.
Free-Living Standing Activity as Assessed by Seismic Accelerometers and Cognitive Function in Community-Dwelling Older Adults: The MIND Trial
Authors: Halloway Shannon , Dhana Klodian , Desai Pankaja , Agarwal Puja , Holland Thomas , Aggarwal Neelum T , Evers Jordi , Sacks Frank M , Carey Vincent J , Barnes Lisa L
Published: April 2021

Background

Few older adults are able to achieve recommended levels of moderate–vigorous physical activity despite known cognitive benefits. Alternatively, less intense activities such as standing can be easily integrated into daily life. No existing study has examined the impact of free-living standing activity during daily life as measured by a device on cognition in older adults. Our purpose was to examine the association between free-living standing activity and cognitive function in cognitively healthy older adults.

Method

Participants were 98 adults aged 65 years or older from the ongoing MIND trial (NCT02817074) without diagnoses or symptoms of mild cognitive impairment or dementia. Linear regression analyses tested cross-sectional associations between standing activity (duration and intensity from the MoveMonitor+ accelerometer/gyroscope) and cognition (4 cognitive domains constructed from 12 cognitive performance tests).

Results

Participants were on average 69.7 years old (SD = 3.7), 69.4% women, and 73.5% had a college degree or higher. Higher mean intensity of standing activity was significantly associated with higher levels of perceptual speed when adjusting for age, gender, and education level. Each log unit increase in standing activity intensity was associated with 0.72 units higher of perceptual speed (p = .023). When we additionally adjusted for cognitive activities and moderate–vigorous physical activity, and then also for body mass index, depressive symptoms, prescription medication use, and device wear time, the positive association remained.

Conclusions

These findings should be further explored in longitudinal analyses and interventions for cognition that incorporate small changes to free-living activity in addition to promoting moderate–vigorous physical activity.
Couple Analysis in the National Social Life, Health, and Aging Project
Authors: Wong Jaclyn S , Hsieh Ning
Published: April 2021

Objectives

Marital and intimate partner relationships are some of the most important social ties that shape older adults’ health and well-being. This paper provides analytic guidelines for the couple data in Round 2 (2010–2011) and Round 3 (2015–2016) of the National Social Life, Health, and Aging Project (NSHAP) to encourage more research on marriage and partnership in late life.

Method

First, we describe the recruitment of couples and outline how to identify partners in the data sets. Second, we provide descriptive information about the couple sample. Third, we offer guidance for analyzing the dyadic data cross-sectionally and longitudinally.

Results

Round 2 interviewed all primary respondents and a sample of their current cohabiting partners and spouses (n = 955 couples). In Round 3, NSHAP reinterviewed the primary respondents and partners who participated in Round 2 (Cohort 1; n = 621 couples) and recruited a new sample of age-eligible adults along with any cohabiting romantic partners (Cohort 2; n = 766 couples). Couples can be identified using a household ID variable in Round 2 and a partner ID variable in Round 3. Demographic characteristics of the couple sample vary by round and cohort.

Discussion

Researchers can use data from either round to conduct cross-sectional dyadic analyses to examine issues faced by older couples. A common strategy for couple analysis is the actor–partner interdependence model. With 2 rounds of couple-level data, researchers may consider using cross-lagged models in their research.
Exploration of changes in health-related behaviours among Saudi Arabian undergraduates in the UK
Authors: Alzain Hassan Mohammed , Leavey Conan , Mitchell Graeme , Gee Ivan , Hall Jason , Al-Subaie Abdullah Saad
Published: April 2021

This project is an exploratory survey of the ways in which living in the UK has affected the health-related behaviours of Saudi Arabian undergraduate students. The study identifies changes in exercise behaviours, dietary and smoking habits and experiences of stress after their move to the UK. In addition, it identifies what the students perceive to be the drivers of these changes. To achieve this, an online questionnaire was developed collecting quantitative data. This was distributed via Facebook groups specifically for Saudi students in the UK. The results demonstrate that a majority of Saudi Arabian undergraduates felt that their behaviours had become healthier since their move to the UK, mainly as a result of a more active lifestyle, derived from reduced reliance on cars, increased daily walking, and a heightened focus on health promoted by their independence, the availability of healthy foods and exposure to a more health-promoting culture. Although these results are based on a relatively small sample, they are surprising since they contradict previous studies on international students, which have generally found negative lifestyle changes during their studies, including increased stress, poorer dietary habits and a decline in physical activity. Although the exploratory nature of the study means that concrete recommendations cannot be made, it nonetheless offers an impetus for further research into how Saudi Arabian students may be encouraged to adopt healthier lifestyles while studying in the UK.
Performance characteristics and working fluid selection for high-temperature organic Rankine cycle driven by solar parabolic trough collector
Authors: Zhao Wei , Xie Ning , Zhang Wei , Yue Jingpeng , Wang Lingbao , Bu Xianbiao , Li Huashan
Published: April 2021

In present paper, thermodynamic analysis and techno-economic assessment of an organic Rankine cycle (ORC) coupled with solar parabolic trough collector (PTC) are investigated. The thermodynamic and economic models, based on the principles of thermodynamics and heat transfer, as well as dynamic economic analysis, are developed for the components of the combined system. By performing a parametric study, the effects of outlet temperature (TPTC,out) and temperature difference between inlet and outlet of PTC (ΔT) and pinch point temperature difference of heat exchangers on the thermo-economic performance are evaluated. Moreover, under reasonable thermodynamic boundary conditions, the optimal operational parameters are obtained via a Pareto frontier solution. It is indicated that the improving TPTC,out is beneficial to the thermo-economic performance. Among the fluid candidates, toluene yields the best energy, exergetic and economic performance. There exists an optimal ΔT at which the thermal and exergy efficiency achieve the maximum. The optimal ΔT is 19–26°C for the screened working fluids. The pinch point temperature difference of evaporator has different impact on the system performance compared with that of condenser. The evaporator pinch point temperature difference has slight influence on the economic performance when it is larger than 10°C. While there is optimized condenser pinch point temperature difference (7–8°C), the economic performance is the optimal. The PTC and heat exchanger are the main source of total investment cost, account for more than 75%. The Pareto frontier solutions can provide a design guide for the decision maker.
Combination versus monotherapy as definitive treatment for Pseudomonas aeruginosa bacteraemia: a multicentre retrospective observational cohort study
Authors: Babich Tanya , Naucler Pontus , Valik John Karlsson , Giske Christian G , Benito Natividad , Cardona Ruben , Rivera Alba , Pulcini Celine , Abdel Fattah Manal , Haquin Justine , MacGowan Alasdair , Grier Sally , Gibbs Julie , Chazan Bibiana , Yanovskay Anna , Ami Ronen Ben , Landes Michal , Nesher Lior , Zaidman-Shimshovitz Adi , McCarthy Kate , Paterson David L , Tacconelli Evelina , Buhl Michael , Mauer Susanna , Rodriguez-Bano Jesus , Morales Isabel , Oliver Antonio , Ruiz de Gopegui Enrique , Cano Angela , Machuca Isabel , Gozalo-Marguello Monica , Martinez Luis Martinez , Gonzalez-Barbera Eva M , Alfaro Iris Gomez , Salavert Miguel , Beovic Bojana , Saje Andreja , Mueller-Premru Manica , Pagani Leonardo , Vitrat Virginie , Kofteridis Diamantis , Zacharioudaki Maria , Maraki Sofia , Weissman Yulia , Paul Mical , Dickstein Yaakov , Leibovici Leonard , Yahav Dafna
Published: April 2021

Background

Pseudomonas aeruginosa bacteraemia is a common and serious infection. No consensus exists regarding whether definitive combination therapy is superior to monotherapy. We aimed to evaluate the impact of combination therapy on mortality.

Methods

This was a multicentre retrospective study (nine countries, 25 centres), including 1277 patients with P. aeruginosa bacteraemia during 2009–15. We evaluated the association between β-lactam plus aminoglycoside or quinolone combination therapy versus β-lactam monotherapy and mortality. The primary outcome was 30 day all-cause mortality. Univariate and multivariate Cox regression analyses were conducted, introducing combination as a time-dependent variable. Propensity score was conducted to adjust for confounding for choosing combination therapy over monotherapy.

Results

Of 1119 patients included, 843 received definitive monotherapy and 276 received combination therapy (59% aminoglycoside and 41% quinolone). Mortality at 30 days was 16.9% (189/1119) and was similar between combination (45/276; 16.3%) and monotherapy (144/843; 17.1%) groups (P = 0.765). In multivariate Cox regression, combination therapy was not associated with reduced mortality (HR 0.98, 95% CI 0.64–1.53). No advantage in terms of clinical failure, microbiological failure or recurrent/persistent bacteraemia was demonstrated using combination therapy. Likewise, adverse events and resistance development were similar for the two regimens.

Conclusions

In this retrospective cohort, no mortality advantage was demonstrated using combination therapy over monotherapy for P. aeruginosa bacteraemia. Combination therapy did not improve clinical or microbiological failure rates, nor affect adverse events or resistance development. Our finding of no benefit with combination therapy needs confirmation in well-designed randomized controlled trials.
Public views about COVID-19 ‘Immunity Passports’
Authors: Hall Mark A , Studdert David M
Published: April 2021

Importance

Discovery of effective vaccines and increased confidence that infection confers extended protection against coronavirus disease (COVID-19) have renewed discussion of using immunity certificates or ‘passports’ to selectively reduce ongoing public health restrictions.

Objective

To determine public views regarding government and private conferral of immunity privileges.

Design and Setting

National on-line survey fielded in June 2020. Participants were randomly asked about either government ‘passports’ or private ‘certificates’ for COVID-19 immunity.

Participants

Adults from a standing panel maintained for academic research, selected to approximate national demographics.

Main Outcomes/Measures

Level of support/opposition to immunity privileges, and whether views vary based on: government vs. private adoption; demographics; political affiliation or views; or various COVID19-related attitudes and experiences.

Results

Of 1315 respondents, 45.2% supported immunity privileges, with slightly more favoring private certificates than government passports (48.1% vs 42.6%, p = 0.04). Support was greater for using passports or certificates to enable returns to high-risk jobs or attendance at large recreational events than for returning to work generally. Levels of support did not vary significantly according to age groups, socioeconomic or employment status, urbanicity, political affiliation or views, or whether the respondent had chronic disease(s). However, estimates from adjusted analyses showed less support among women (odds ratio, 0.64; 95% confidence interval, 0.51 to 0.80), and among Hispanics (0.56; 0.40 to 0.78) and other minorities (0.58; 0.40 to 0.85) compared with whites, but not among blacks (0.83; 0.60 to 1.15). Support was much higher among those who personally wanted a passport or certificate (75.6% vs 24.4%) and much lower among those who believed this would harm the social fabric of their community (22.9% vs 77.1%).

Conclusions and Relevance

Public views are divided on both government or private uses of immunity certificates, but, prior to any efforts to politicize the issues, these views did not vary along usual political lines or by characteristics that indicate individual vulnerability to infection. Social consensus on the desirability of an immunity privileges programs may be difficult to achieve.
Genomic Risk Score for Melanoma in a Prospective Study of Older Individuals
Authors: Bakshi Andrew , Yan Mabel , Riaz Moeen , Polekhina Galina , Orchard Suzanne G , Tiller Jane , Wolfe Rory , Joshi Amit , Cao Yin , McInerney-Leo Aideen M , Yanes Tatiane , Janda Monika , Soyer H Peter , Cust Anne E , Law Matthew H , Gibbs Peter , McLean Catriona , Chan Andrew T , McNeil John J , Mar Victoria J , Lacaze Paul
Published: April 2021

Background

Recent genome-wide association meta-analysis for melanoma doubled the number of previously identified variants. We assessed the performance of an updated polygenic risk score (PRS) in a population of older individuals, where melanoma incidence and cumulative ultraviolet radiation exposure is greatest.

Methods

We assessed a PRS for cutaneous melanoma comprising 55 variants in a prospective study of 12 712 individuals in the ASPirin in Reducing Events in the Elderly Trial. We evaluated incident melanomas diagnosed during the trial and prevalent melanomas diagnosed preenrolment (self-reported). Multivariable models examined associations between PRS as a continuous variable (per SD) and categorical (low-risk [0%-20%], medium-risk [21%-80%], high-risk [81%-100%] groups) with incident melanoma. Logistic regression examined the association between PRS and prevalent melanoma.

Results

At baseline, mean participant age was 75 years; 55.0% were female, and 528 (4.2%) had prevalent melanomas. During follow-up (median = 4.7 years), 120 (1.0%) incident cutaneous melanomas occurred, 98 of which were in participants with no history. PRS was associated with incident melanoma (hazard ratio = 1.46 per SD, 95% confidence interval [CI] = 1.20 to 1.77) and prevalent melanoma (odds ratio [OR] = 1.55 per SD, 95% CI = 1.42 to 1.69). Participants in the highest-risk PRS group had increased risk compared with the low-risk group for incident melanoma (OR = 2.51, 95% CI = 1.28 to 4.92) and prevalent melanoma (OR = 3.66, 95% CI = 2.69 to 5.05). When stratifying by sex, only males had an association between the PRS and incident melanoma, whereas both sexes had an association between the PRS and prevalent melanoma.

Conclusions

A genomic risk score is associated with melanoma risk in older individuals and may contribute to targeted surveillance.
Argonaute integrated single-tube PCR system enables supersensitive detection of rare mutations
Authors: Liu Qian , Guo Xiang , Xun Guanhua , Li Zhonglei , Chong Yuesheng , Yang Litao , Wang Hongxia , Zhang Fengchun , Luo Shukun , Cui Li , Zhao Pengshu , Ye Xingyu , Xu Heshan , Lu Hui , Li Xiao , Deng Zixin , Li Kai , Feng Yan
Published: April 2021

Technological advances in rare DNA mutations detection have revolutionized the diagnosis and monitoring of tumors, but they are still limited by the lack of supersensitive and high-coverage procedures for identifying low-abundance mutations. Here, we describe a single-tube, multiplex PCR-based system, A-Star, that involves a hyperthermophilic Argonaute from Pyrococcus furiosus (PfAgo) for highly efficient detection of rare mutations beneficial from its compatibility with DNA polymerase. This novel technique uses a specific guide design strategy to allow PfAgo selective cleavage with single-nucleotide resolution at 94°C, thus mostly eliminating wild-type DNA in the denaturation step and efficiently amplifying rare mutant DNA during the PCR process. The integrated single-tube system achieved great efficiency for enriching rare mutations compared with a divided system separating the cleavage and amplification. Thus, A-Star enables easy detection and quantification of 0.01% rare mutations with ≥5500-fold increase in efficiency. The feasibility of A-Star was also demonstrated for detecting oncogenic mutations in solid tumor tissues and blood samples. Remarkably, A-Star achieved simultaneous detection of multiple oncogenes through a simple single-tube reaction by orthogonal guide-directed specific cleavage. This study demonstrates a supersensitive and rapid nucleic acid detection system with promising potential for both research and therapeutic applications.