bluuebunny/crossref_metadata_2025 huggingface dataset:
The yeast FIT2 homologs are necessary to maintain cellular proteostasis and membrane lipid homeostasis
Authors: Yap Wei Sheng , Shyu Peter , Gaspar Maria Laura , Jesch Stephen A. , Marvalim Charlie , Prinz William A. , Henry Susan A. , Thibault Guillaume
Published: October 2020

Lipid droplets (LDs) are implicated in conditions of lipid and protein dysregulation. The fat storage-inducing transmembrane (FIT; also known as FITM) family induces LD formation. Here, we establish a model system to study the role of the Saccharomyces cerevisiae FIT homologues (ScFIT), SCS3 and YFT2, in the proteostasis and stress response pathways. While LD biogenesis and basal endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR) remain unaltered in ScFIT mutants, SCS3 was found to be essential for proper stress-induced UPR activation and for viability in the absence of the sole yeast UPR transducer IRE1. Owing to not having a functional UPR, cells with mutated SCS3 exhibited an accumulation of triacylglycerol within the ER along with aberrant LD morphology, suggesting that there is a UPR-dependent compensatory mechanism that acts to mitigate lack of SCS3. Additionally, SCS3 was necessary to maintain phospholipid homeostasis. Strikingly, global protein ubiquitylation and the turnover of both ER and cytoplasmic misfolded proteins is impaired in ScFITΔ cells, while a screen for interacting partners of Scs3 identifies components of the proteostatic machinery as putative targets. Together, our data support a model where ScFITs play an important role in lipid metabolism and proteostasis beyond their defined roles in LD biogenesis.

This article has an associated First Person interview with the first author of the paper.
An evolutionarily distinct chaperone promotes 20S proteasome α-ring assembly in plants
Authors: Marshall Richard S. , Gemperline David C. , McLoughlin Fionn , Book Adam J. , Hofmann Kay , Vierstra Richard D.
Published: October 2020

The core protease (CP) subcomplex of the 26S proteasome houses the proteolytic active sites and assumes a barrel shape comprised of four co-axially stacked heptameric rings formed by structurally related α- and β-subunits. CP biogenesis typically begins with the assembly of the α-ring, which then provides a template for β-subunit integration. In eukaryotes, α-ring assembly is partially mediated by two hetero-dimeric chaperones, termed Pba1–Pba2 (Add66) and Pba3–Pba4 (also known as Irc25–Poc4) in yeast. Pba1–Pba2 initially promotes orderly recruitment of the α-subunits through interactions between their C-terminal HbYX or HbF motifs and pockets at the α5–α6 and α6–α7 interfaces. Here, we identified PBAC5 as a fifth α-ring assembly chaperone in Arabidopsis that directly binds the Pba1 homolog PBAC1 to form a trimeric PBAC5–PBAC1–PBAC2 complex. PBAC5 harbors a HbYX motif that docks with a pocket between the α4 and α5 subunits during α-ring construction. Arabidopsis lacking PBAC5, PBAC1 and/or PBAC2 are hypersensitive to proteotoxic, salt and osmotic stresses, and display proteasome assembly defects. Remarkably, whereas PBAC5 is evolutionarily conserved among plants, sequence relatives are also dispersed within other kingdoms, including a scattered array of fungal, metazoan and oomycete species.
Breast-iRRISC: a novel model for predicting the individualised lifetime risk of radiation-induced breast cancer from a single screening event
Authors: Hooshmand Sahand , Reed Warren M. , Suleiman Mo’ayyad E. , Brennan Patrick C.
Published: October 2020

Objectives:

This work establishes the prototype of a new innovative risk model that aims to evaluate the total risk involved with screening mammography for each individual female. This has been specifically designed to accommodate any combination of lifetime screening regimes, using only the information gathered from a single mammographic examination.

Methods:

This model prototype was developed with the aid of a large dataset of images from the Cancer Institute New South Wales (CINSW) with over 30,000 images from over 7000 examinations. Each examination is derived from a separate female.

Results:

This prototype which we have called Breast Individualised Risk of Radiation-Induced Screening Cancer (Breast-iRRISC) is a novel tool for the assessment of the lifetime risk involved with screening mammography. The results demonstrate the applicability of this approach to the various screening regimes utilised around the globe, in addition to the personalised screening frequency patterns females have undergone and are likely to receive in the future.

Conclusions:

This unique tailored approach to risk assessment will further empower females and clinicians towards a more informed clinical decision process regarding future imaging pathways. It will also inform health policy decisions regarding alternate screening durations and intervals.

Advances in knowledge:

Breast-iRRISC is a novel tool that provides females, clinicians and health policymakers around the globe with the ability to quantify the lifetime risk of radiation-induced breast cancer from screening mammography on an individual level from a single exposure.
The virtual circular genome model for primordial RNA replication
Authors: Zhou Lijun , Ding Dian , Szostak Jack W.
Published: October 2020

We propose a model for the replication of primordial protocell genomes that builds upon recent advances in the nonenzymatic copying of RNA. We suggest that the original genomes consisted of collections of oligonucleotides beginning and ending at all possible positions on both strands of one or more virtual circular sequences. Replication is driven by feeding with activated monomers and by the activation of monomers and oligonucleotides in situ. A fraction of the annealed configurations of the protocellular oligonucleotides would allow for template-directed oligonucleotide growth by primer extension or ligation. Rearrangements of these annealed configurations, driven either by environmental fluctuations or occurring spontaneously, would allow for continued oligonucleotide elongation. Assuming that shorter oligonucleotides were more abundant than longer ones, replication of the entire genome could occur by the growth of all oligonucleotides by as little as one nucleotide on average. We consider possible scenarios that could have given rise to such protocell genomes, as well as potential routes to the emergence of catalytically active ribozymes and thus the more complex cells of the RNA World.
Taxono-genomics description of Olsenella lakotia SW165T sp. nov., a new anaerobic bacterium isolated from the cecum of feral chicken
Authors: Wongkuna Supapit , Ghimire Sudeep , Janvilisri Tavan , Doerner Kinchel , Chankhamhaengdecha Surang , Scaria Joy
Published: October 2020

Background: The microbial community residing in the animal gastrointestinal tract play a crucial role in host health. Because of the high complexity of gut microbes, many microbes remain unclassified. Deciphering the role of each bacteria in health and diseases is only possible after its culture, identification, and characterization. During the culturomics study of feral chicken cecal sample, we cultured a possible novel strain SW165T.

Methods: For the possible novel strain SW165T, phenotypic characterization was performed using colony morphology, Gram staining, growth in different temperature and pH and motility. Biochemical assays included carbon source utilization, enzymatic activity, cellular fatty acids and short chain fatty acid production. 16S rRNA sequencing and whole genome sequencing and comparison was performed for genetic analysis.

Results: This strain was isolated from cecal content of feral chickens in Brookings, South Dakota, USA. Phylogenetic analyses based on 16S rRNA gene sequence revealed that the closest valid neighbor was Olsenella profusa DSM 13989T (96.33% similarity) within the family Atopobiaceae. Cells were Gram-strain-positive and obligately anaerobic bacilli in chains. The optimum temperature and pH for the growth of the microorganism were 37-45oC and pH 6.0-7.5 respectively.  This strain produced acetic acid as the primary fermentation product. Major fatty acids were C12:0, C14:0, C14:0 DMA and summed feature 1 (C13:1 at 12-13 and C14:0 aldehyde). Strain SW165T exhibited a genome size of 2.43 Mbp with a G+C content of 67.59 mol%, which is the second highest G+C content among members of the genus Olsenella. The digital DNA-DNA hybridization and OrthoANI values between SW165T and DSM 13989T were only 17.6 ± 5.3 and 74.35%, respectively.

Conclusion: Based on the phenotypic, biochemical, and genomic analyses, we propose the new species of the genus Olsenella, and name it Olsenella lakotia SW165T sp. nov., (=DSM 107283 =CCOS 1887) as the type strain.
Road traffic injuries in Nepal during COVID-19 lockdown
Authors: Sedain Bhagabati , Pant Puspa Raj
Published: October 2020

Background: As the world is busy addressing COVID-19, road traffic injuries, another major cause of deaths is continuously killing people on the roads. In Nepal, there were frequent media reports of occurrences of road crashes, injuries, and deaths despite nationwide lockdown. This paper aims to describe the situation of road traffic crashes and casualties during the period of complete lockdown.

Methods: This study used secondary data from two sources: Nepal Police and media reports between 24 March and 14 June 2020 (because the government lifted the nationwide lockdown from 15 June 2020). Available details of crashes, deaths, and injuries for this period were extracted from media reports and the summary data that was obtained from the Police. Narrative comparison is done between the data for the same period from both the sources, where possible.

Results: Nepal Police recorded 1,801 incidents of road crashes during the 82 days of the COVID-19 lockdown with 256 deaths (on average 3.1 deaths daily) and 1,824 injuries (on average 22.2 injuries daily). Motorcycles comprised over 21% of all vehicles involved in crashes. Ambulances and other vehicles for essential services were also found to be involved in crashes. Speeding itself was the cause for almost a quarter of the incidents during the lockdown.

Conclusions: Even when the movement restrictions were imposed in Nepal, the number of road crashes was not substantially reduced. Media reports were mainly found to be reporting the crashes where deaths occurred, but police records also included nonfatal injuries. The incidence of crashes in this period shows that it is important to work for road safety to save lives from road traffic crashes in Nepal.
Generalized Structured Component Analysis in candidate gene association studies: applications and limitations
Authors: Thompson Paul A. , Bishop Dorothy V. M. , Eising Else , Fisher Simon E. , Newbury Dianne F.
Published: October 2020

Background: Generalized Structured Component Analysis (GSCA) is a component-based alternative to traditional covariance-based structural equation modelling. This method has previously been applied to test for association between candidate genes and clinical phenotypes, contrasting with traditional genetic association analyses that adopt univariate testing of many individual single nucleotide polymorphisms (SNPs) with correction for multiple testing.

Methods: We first evaluate the ability of the GSCA method to replicate two previous findings from a genetics association study of developmental language disorders. We then present the results of a simulation study to test the validity of the GSCA method under more restrictive data conditions, using smaller sample sizes and larger numbers of SNPs than have previously been investigated. Finally, we compare GSCA performance against univariate association analysis conducted using PLINK v1.9.

Results: Results from simulations show that power to detect effects depends not just on sample size, but also on the ratio of SNPs with effect to number of SNPs tested within a gene. Inclusion of many SNPs in a model dilutes true effects.

Conclusions: We propose that GSCA is a useful method for replication studies, when candidate SNPs have been identified, but should not be used for exploratory analysis.
Knights Exchange Puzzle—Teaching the Efficiency of Modeling
Authors: Iranpoor Mehdi
Published: October 2020

Puzzles and games enhance the quality of teaching by creating an enjoyable, interactive, and playful atmosphere. The knight exchange is a famous, very old, and amusing game on the chessboard. This puzzle was used by the author to teach modeling in a mathematical programming course designed for graduate students. The aim was to teach the students the efficiency of the models. Accordingly, first, a binary programming formulation was developed. This formulation was, however, found to be inefficient, and tremendous time (i.e., more than four hours) and a large amount of processing memory were needed to solve the puzzle. The puzzle was subsequently formulated as a minimum cost network flow problem. The latter formulation outperformed the general binary formulation by solving the puzzle in less than a minute. The network formulation could also save the required processing memory. The results could help students to learn the value of modeling combinatorial optimization problems as network flows.
Entry of Platforms into Complementary Hardware Access Product Markets
Authors: Sharma Siddhartha , Mehra Amit
Published: October 2020

This paper analyzes the entry of digital platforms such as Google into complementary hardware markets (e.g., internet service provision) using a game-theoretic model.
Elaborating or Aggregating? The Joint Effects of Group Decision-Making Structure and Systematic Errors on the Value of Group Interactions
Authors: Keck Steffen , Tang Wenjie
Published: October 2020

We explore when group interactions will have a positive effect on the accuracy of quantitative judgments. The results from three laboratory experiments revealed that the value of group interactions, compared with a statistical aggregation of individual judgments, differed strongly between groups in which decisions were made based on consensus, compared with groups with a randomly assigned group leader, and that this effect was moderated by the level of systematic error among group members. In particular, when systematic errors were low, group interactions generally provided little value, and groups’ decision-making structure (consensus versus leader based) did not have a significant effect on the value of group interactions. However, when the level of systematic error was high, the value of interactions in groups with a randomly designated leader was strongly positive and significantly higher than in groups with a consensus decision-making structure where interactions still provided only little value. Moreover, we found that this effect was mediated by information elaboration—which was higher in leader groups but only had a significant effect on the value of group interactions when there was a high level of systematic error. Finally, we also identified two important boundary conditions for these results. In particular, leader groups did not provide more value than consensus groups in the presence of strong systematic errors when leaders were assigned based on prior individual performance rather than randomly or when group members had only little expertise in the task.

This paper was accepted by Yuval Rottenstreich, decision analysis.
Outsourcing Tasks Online: Matching Supply and Demand on Peer-to-Peer Internet Platforms
Authors: Cullen Zoë , Farronato Chiara
Published: October 2020

We study the growth of online peer-to-peer markets. Using data from TaskRabbit, an expanding marketplace for domestic tasks at the time of our study, we show that growth varies considerably across cities. To disentangle the potential drivers of growth, we look separately at demand and supply imbalances, network effects, and geographic heterogeneity. First, we find that supply is highly elastic: in periods when demand doubles, sellers perform almost twice as many tasks, prices hardly increase, and the probability of requested tasks being matched falls only slightly. The first result implies that in markets where supply can accommodate demand fluctuations, growth relies on attracting buyers at a faster rate than sellers. Second and perhaps most surprisingly, we find no evidence of network effects in matching: doubling the number of buyers and sellers only doubles the number of matches. Third, we show that the cities where market fundamentals promote efficient matching of buyers and sellers are also those that are the fastest growing. This heterogeneity in matching efficiency is related to two measures of market thickness: geographic density (buyers and sellers living close together) and level of task standardization (buyers requesting homogeneous tasks). Our results have two main implications for peer-to-peer markets in which network effects are limited by the local and time-sensitive nature of the services exchanged. First, marketplace growth largely depends on strategic geographic expansion. Second, a competitive rather than winner-take-all equilibrium may arise in the long run.

This paper was accepted by Bruno Cassiman, business strategy.
Big Fish, Big Pond? The Joint Effect of Formal and Informal Core/Periphery Positions on the Generation of Incremental Innovations
Authors: Maoret Massimo , Tortoriello Marco , Iubatti Daniela
Published: October 2020

In this paper, we apply a core/periphery framework to an intraorganizational context to study the interplay between formal and informal core/periphery structures. Specifically, we consider how core positions occupied by inventors in the corporate research and development division of a large multinational high-tech company affect their ability to generate incremental innovations. We theorize and empirically observe that formal and informal core positions have positive and independent effects on the generation of incremental innovations. These effects have a multiplicative impact on innovative productivity when inventors who are core in the informal knowledge-sharing network are also affiliated with a core organizational unit. We also observe, however, that the positive effect of being located at the core of both the informal and formal structures is negatively moderated by individuals’ distribution of knowledge ties when these reach outside the core of their informal knowledge-sharing network.
The New Food Truck in Town: Geographic Communities and Authenticity-Based Entrepreneurship
Authors: Schifeling Todd , Demetry Daphne
Published: October 2020

Authenticity is a valuable attribution for organizations, but one that raises a challenge of audience acceptance for innovative entrepreneurs. In particular, organizations that depart from an established type risk being judged as inauthentic. However, entrepreneurs may be able to overcome this challenge by basing their authenticity on notions of craft—such as skilled hands-on techniques, sophisticated ingredients, and small-scale artistry rather than mass industrial manufacturing—that better support innovation. We propose that communities vary in the extent to which they embrace craft production as an evolved understanding of authenticity that is less concerned with conformity to type. This local context, in turn, conditions the likelihood of entrepreneurs creating innovative ventures that rely on perceptions of craft authenticity. We develop this argument through a mixed-methods study of the spatially uneven emergence of gourmet food trucks across the United States. Our findings contribute to research on authenticity and the geography of entrepreneurship and innovation.
The Ecology of Management Concepts
Authors: Denrell Jerker , Kovács Balázs
Published: October 2020

How does the popularity of a concept depend on how it contrasts with and complements existing concepts? We argue that being similar to existing concepts, being located in a popular domain, and being combined with similar existing concepts are important for gaining attention early on but less important and even negative for sustaining popularity. To examine this question, we focus on the rise and fall of management concepts. We analyze data on the rise and fall of keywords in the Harvard Business Review between 1922 and 2010. Multiple tests confirm our hypotheses. The implication is that lessons learned from studies of popular concepts can be misleading as guides for how to make novel concepts popular.
The Acton Model: support for women with female genital mutilation
Authors: Albert Juliet , Wells Mary
Published: October 2020

Objectives

To identify the presenting characteristics, needs and clinical management of non-pregnant women with female genital mutilation who attended the Sunflower clinic, a midwife-led specialist service.

Methods

This was a retrospective case series review examining referral patterns, clinical findings and subsequent management between 1 April 2018 and 31 March 2019.The review was conducted at a multi-disciplinary female genital mutilation clinic for non-pregnant women aged 18 years and over in West London.

Results

There were 182 attendances at the clinic (88 new patients; 94 follow-up appointments). Almost half (52%) had type 3 mutilation, 32% had type 2; 9% had a history of type 3; 5% had type 1; one had type 4 and one declined assessment. A total of 35 women (40%) disclosed at least one psychological symptom (such as depression, anxiety, flashbacks, nightmares) during initial consultation.

Conclusions

Non-pregnant women attending female genital mutilation services present with a wide range of psychological and physical problems. Holistic woman-centred models of care appear to facilitate access to deinfibulation and counselling, which in turn may reduce long-term costs to the NHS. Safeguarding is an intrinsic part of midwives' work and is sometimes complex. The authors recommend a revision of the World Health Organization classifications to specify partial or total removal of the clitoral glans (rather than the clitoris as a whole) as this is inaccurate and may have a negative psychological impact for women.
COVID-19 and the risk to black, Asian and minority ethnic women during pregnancy
Authors: Esegbona-Adeigbe Sarah
Published: October 2020

Black, Asian and minority ethnic (BAME) women in the UK have increased maternal mortality rates compared to other groups of women. Unfortunately, according to preliminary findings, the COVID-19 pandemic has contributed to mortality rates for BAME women, raising concerns that pregnant BAME women are facing greater health disparities during the pandemic. A review of 427 pregnant women admitted to hospital in the UK with confirmed COVID-19 infection found that over half (56%) were from black or other ethnic minority groups. How BAME women navigate maternity services during the COVID-19 pandemic requires a vigilant review of their needs on an individual basis. This is particularly relevant for hard-to-reach women, such as recent immigrants and asylum seekers, who may encounter difficulties accessing or engaging with maternity services. Therefore, it is imperative to reassess and highlight the challenges faced by pregnant BAME women during the pandemic. The disruption of maternity services and diversion of resources away from essential pregnancy care because of prioritising the COVID-19 response is expected to increase risks of maternal mortality.
Change in Knowledge and Awareness in Teacher Education on Satoyama Environmental Learning: Through a Blend of Learning Spaces, Methods and Media
Authors: Miyaji Isao , Fukui Hirokazu
Published: October 2020

Lessons on Satoyama environmental education were held for undergraduate students who are training to be educators. The lessons blend inquiry-based learning through research using ICT tools and experiential learning in a complementary manner. Students learn about the underlying concepts about the environment from a global perspective through inquiry-based learning; experiential learning can encourage students to get involved with the environment at the local level and also develop abilities and skills to conduct classes in environmental education. This paper investigated how the lessons influenced the students in these areas: knowledge of technical terms related to Satoyama environmental education, students’ confidence and desire to engage in environmental education, and how awareness of their own abilities were improved through the lessons. To understand the impact of the lessons quantitatively, survey contents of the subjective awareness etc. were printed on A4 paper medium and were distributed. The medium were collected after filling them during class. The data are analyzed using Wilcoxon signed-rank test, Wilcoxon rank sum test, and cluster analysis. As a result, overall recognition of technical terms increases on post-survey. There is an increase in the mean score for all items on confidence and desire to engage in environmental education. For the awareness on abilities, students feel that their abilities increased overall across all items.
Effects of tourniquet use in paediatric lower leg surgery
Authors: Hanna Rewais B. , Nies Matthew , Lang Pamela J. , Halanski Matthew
Published: October 2020

Background

The purpose of this study is to evaluate the use of the tourniquet and its effect on post-operative pain in the paediatric population following lower leg procedures.

Methods

A retrospective study of paediatric patients (under the age of 18) undergoing inpatient orthopaedic procedure below the knee performed at a single academic institution between 1st December 2013 and 31st January 2019 was conducted. Primary outcome measures of total opioid consumption during hospital stay and pre-operative nerve block utilization were retrieved from the electronic medical record (EMR). Secondary outcome measures of blood loss, tourniquet time, procedure time and length of hospital stay were also retrieved. Student's t-tests were used to assess statistical significance between two sample means.

Results

The final analysis included 204 paediatric procedures, 118 of which used a tourniquet and 86 of which did not. Paediatric patients with a tourniquet had significantly more opioid consumption post-operatively in the form of weight-based morphine equivalents/length of stay (p = 0.01) compared to those who had no tourniquet. This held true for males (p = 0.049) and females (p = 0.04) respectively. We did not see an increase in wound complications or return trips to the operating room in the tourniquet cohort. All procedures included an osseous component except one procedure in the non-tourniquet group.

Conclusion

Minimizing opioid consumption may be achieved by avoiding tourniquet use in paediatric patients with lower leg procedures. In non-anaemic paediatric patients, it is reasonably risk-free to perform these surgeries without the use of tourniquet to decrease opioid dependence in the post-­operative period.

Level of evidence

III
Efficacy of corticosteroid in decreasing scoliosis and extending time to loss of ambulation in a single clinic: An effectiveness trial
Authors: Sussman Michael D. , Sienko Susan E. , Buckon Cathleen E. , Hilton Coleman , De Mattos Camila Bedeschi , d'Amato Charles
Published: October 2020

Purpose

Pharmacologic doses of corticosteroid (CS) have been shown to ameliorate the progression of Duchenne muscular dystrophy (DMD) preserving strength, pulmonary function and ambulation as well as reducing the incidence of scoliosis. However, there are serious side effects of CS, which may impact dose tolerance. The purpose of this study was to compare the magnitude of positive CS effects on patients in our clinic to those reported in the literature.

Methods

We retrospectively reviewed medical records and radiographs of 142 DMD patients who were seen between 1st January 1991 and 31st December 2017.

Results

In total, 101 boys met study inclusion criteria. Of these 32 were steroid naïve, 37 took the recommended dose (standard of care, SOC) of Prednisone or Deflazacort, and 32 took a lower dose (LD). Following initiation of CS, both treatment groups showed an increase in weight velocity and decrease in linear growth velocity. Although there was a trend to later loss of ambulation (LOA) in the SOC group relative to the naïve group by one year, this was not significant, however, a small subgroup of boys on Deflazacort showed a 3.4 year later LOA than the naïve group. The incidence of scoliosis was reduced from 69% in the naïve, to 41% in the LD and 47% in the SOC group.

Conclusions

Although there was a reduction in the incidence of scoliosis, it was not as robust as seen elsewhere. Many published studies have inadequate data on scoliosis probably due to the lack of inclusion of orthopaedists in the study group.

Level of evidence

IV
Elegant Gaussian beams: nondiffracting nature and self-healing property
Authors: Chabou Saoussene , Bencheikh Abdelhalim
Published: October 2020

Alongside the well-known solutions of standard beams, elegant Gaussian beams (eGBs) have been presented as alternative solutions to the paraxial wave equation. In this work, we show that the eGBs in cartesian (elegant Hermite–Gauss) and cylindrical (elegant Laguerre–Gauss) coordinates are asymptotically equivalent to pseudo-nondiffracting beams (pNDBs) in the same coordinates (cosine–Gauss and Bessel–Gauss, respectively). A theoretical comparison of their intensity distributions at different planes without and with obstruction is given, allowing to revisit and discuss the diffraction-free nature and self-healing property. The obtained results demonstrate that both families of beams are indistinguishable and have similar propagation features, which means that the eGBs class can be used as an alternative to pNDBs.
Lensless on-chip LED array microscope using amplitude and phase masks
Authors: Hassan Atif , Khan Sohail , Rasul Khurram , Hussain Anwar
Published: October 2020

A cost-effective, compact, and portable optical system using multi-angle illumination for retrieval of the amplitude and phase of a sample is implemented in this paper. The system consists of a matrix of LED followed by a mask, a USAF resolution chart, and a detector in a column. The sample information is collected by the detector directly without any objective lens. The sample information is encoded by the mask at a sensor plane during the reconstruction process. To retrieve the sample information from captured raw images corresponding to each LED illumination, the backward propagation model is applied. Three types of masks are used: a phase mask having pixel values from 0 to

2

π

, an amplitude mask, and a combination of a phase and an amplitude mask with random distribution. The applications of such type of technique are most common in biomedical engineering for infection diagnostic purposes. In the future, the commercial demand of such lensless microscope would be high due to its simplicity and fast image processing capacity.
Theoretical study of silicon-based Bragg mirrors for cavity QED applications
Authors: Maldaner J. , Al Sumaidae S. , DeCorby R. G.
Published: October 2020

We conducted a theoretical study on the potential use of amorphous hydrogenated silicon (a-Si:H) as the high-index material in quarter-wave-stack Bragg mirrors for cavity quantum electrodynamics applications. Compared to conventionally employed

T

a

2

O

5

, a-Si:H provides a much higher-index contrast with

S
i

O

2

, thus promising significantly reduced layer-number requirements and a smaller mode volume. Silicon-based mirrors offer the additional advantage of providing a wide omnidirectional reflection band, which allows greater control of the background electromagnetic modes. From numerical studies at 850 nm, we show that a-Si:H-based mirrors could enable significant improvements with respect to maximum Purcell factor, cooperativity, and spontaneous emission coupling factor, in addition to their potential to reduce fabrication complexity. These advantages are anticipated to be even more compelling at longer wavelengths.
Band calculations using broadband Green’s functions and the KKR method with applications to magneto-optics and photonic crystals
Authors: Gao Ruoxing , Tsang Leung , Tan Shurun , Liao Tien-Hao
Published: October 2020

In this paper, we develop a method of simulations of using the broadband Green’s function (BBGF) in the Korringa Kohn Rostoker (KKR) method. The merit of the method is broadband such that once the initial setup is completed, the calculation at every frequency is calculated rapidly. The broadband Green’s function consists of a frequency-independent spatial summation and a spectral summation that has most of the factors frequency independent. Both summations have fast convergence. Analytical expressions of broadband coefficients of cylindrical waves are derived from the BBGF. The broadband cylindrical waves coefficients are then combined with the KKR method to calculate the determinant equation for a wide range of frequencies. Numerical results of the band diagrams and band surface currents are illustrated for magneto-optics and photonic crystals. The CPU time requirements, including setup, using MATLAB on a standard laptop, for computing the determinant at 1000 frequencies at a Bloch vector are 0.411 s and 1.206 s, respectively, for the cases of topological crystal of small scatterer relative to cell size and the photonic crystal of large scatterer comparable to cell size.
Effect of dipole–dipole interactions on the one-photon and two-photon photoluminescence in an ensemble of quantum dots doped in a polymer matrix
Authors: Persaud Patrick D. , Singh Mahi R.
Published: October 2020

We have developed a theory for the one-photon and two-photon fluorescence of a nanohybrid composite comprised of an ensemble of quantum dots encased in a matrix of polymer. The quantum dots are comprised of four-level quantum emitters encased within a coating of dielectric material. The fluorescence of the quantum dot system is calculated using the master equation method where dipole–dipole interaction (DDI) coupling is present. The application of a probe field to the nanohybrid composite material in conjunction with the DDI between the quantum dots generates an enhancement of both the single-photon and double-photon fluorescence, and in certain conditions causes spectrum splitting. With a strong DDI field, the two-photon emission spectrum experiences slight quenching and shifts from one peak to two peaks. The dressed states are a result of strong coupling effects between the DDI field and the quantum dots. We generated an analytical expression for the fluorescence spectrum and intensity, and quantitatively compared it to experimental data in which ZnSe quantum dots were embedded within a P3HT polymer film, with our theory strongly correlating with the experiment. We also quantitatively compared our theory with experimental data that demonstrated the single-photon emission spectrum of colloidal quantum dots comprised of a CdZnS/ZnS gradient structure in varying probe field strengths. We found that our theory predicted the spectrum peak splitting that the experiment produced.
Inverse design of a 1D dielectric metasurface by topology optimization: fluctuations-trend analysis assisted by a diamond-square algorithm
Authors: Edee K. , Rhouma M. Ben , Fan J.-A. , Antezza M. , Gippius N. , Wang E. , Plumey J.-P. , Granet G. , Guizal B.
Published: October 2020

We present a topology optimization method for a 1D dielectric metasurface, coupling the classical fluctuations-trend analysis (FTA) and diamond-square algorithm (DSA). In classical FTA, a couple of device distributions termed fluctuation or mother and trends or father, with specific spectra, is initially generated. The spectral properties of the trend function allow one to efficiently target the basin of optimal solutions. For optimizing a 1D metasurface to deflect a normally incident plane wave into a given deflecting angle, a cosine-like function has been identified to be an optimal father profile, allowing one to efficiently target a basin of local minima. However, there is no efficient method to predict the father profile number of oscillations that effectively allows one to avoid undesirable local optima. It would be natural to suggest a randomization of the variable that controls the number of oscillations of the father function. However, one of the main drawbacks of the randomness searching process is that, combined with a gradient method, the algorithm can target undesirable local minima. The method proposed in this paper improves the possibility of classical FTA to avoid the trapping of undesirable local optimal solutions. This is accomplished by extending the initial candidate family to higher-quality offspring that are generated due to the DSA. Doing so ensures that the main features of the best trends are stored in the genes of all offspring structures.
Free space continuous-variable quantum key distribution with practical links
Authors: Li Ming , Wang Tianyi , Han Jiawei , Yu Zhongyuan , Cvijetic Milorad , Ye Han , Liu Yumin
Published: October 2020

The transmittance fluctuation resulting from free space optics will impart the continuous-variable quantum key distribution (CV-QKD). In this paper, we study the CV-QKD over free space by taking practical transmittance fluctuation into account. The transmittance is modeled following the Gaussian distribution, which reflects the most realistic fluctuation since all sources of perturbation are required to be incorporated together in practice. The comprehensive comparison between the practical model and existing models in secret key rate is drawn. The numerical results reveal that the existing model of uniform distribution underestimates the impact of air link for both slow and fast fading scenarios, and the practical secret key rate will suffer severer degradation. Further, as the variance of the Gaussian model decreases, the secret key rate degrades as well. Also, a comparison between heterodyne and homodyne detection schemes is made, and we found that the heterodyne detection outperforms the homodyne detection in the secret key rate for both the slow and fast fading air quantum channels.
Laser energy absorption prediction of silicon substrate surface from a mid- and high-spatial frequency error
Authors: Tian Ye , Zhou Gang , Xue Shuai , Shi Feng , Song Ci , Li Furen , Zhong Yaoyu , Shen Yongxiang
Published: October 2020

Additional laser energy absorption of optical elements limits the further development of high-energy laser systems. In engineering, inexpensive and precise absorption test technology is essential. We attempt to predict energy absorption via surface spatial error value based on the roughness-induced absorption (RIA) theory. However, the absorption coefficients cannot match roughness values measured with an atomic force microscope or white light interferometer. We find three influencing factors and optimize the definition of RIA to spatial error-induced absorption (SEIA). SEIA is proportional to δ2 of a mid- and high-spatial frequency error in a certain frequency range. This range depends on laser diameter, wavelength, and coating. Excluding the absorption induced by fabrication defects, the total absorption can be classified into SEIA and background absorption (BGA). BGA is decided by material and process technology, which can be obtained by calculations. The sum of SEIA and BGA is predictable because both can be estimated. The substrate absorption of high-energy optics can be semi-quantificationally predicted. SEIA provides a new angle to research element-absorbed laser energy for high-power laser technologies.
Optimal quantum phase estimation in an atomic gyroscope based on a Bose-Hubbard model
Authors: Shao Lei , Li Weiyao , Wang Xiaoguang
Published: October 2020

We investigate the optimal quantum state for an atomic gyroscope based on a three-site Bose-Hubbard model. In previous studies, various states such as the uncorrelated state, the BAT state and the NOON state are employed as the probe states to estimate the phase uncertainty. In this article, we present a Hermitian operator

H

and an equivalent unitary parametrization transformation to calculate the quantum Fisher information for any initial states. Exploiting this equivalent unitary parametrization transformation, we can seek the optimal state that gives the maximal quantum Fisher information on both lossless and lossy conditions. As a result, we find that the squeezed entangled state (SES) and the entangled even squeezed state (EESS) can significantly enhance the precision for moderate loss rates compared with previous proposals.
Structure-dependent amplification for denoising and background
correction in Fourier ptychographic microscopy
Authors: Claveau Rémy , Manescu Petru , Fernandez-Reyes Delmiro , Shaw Michael
Published: October 2020

Fourier Ptychographic Microscopy (FPM) allows high resolution imaging using iterative phase retrieval to recover an estimate of the complex object from a series of images captured under oblique illumination. FPM is particularly sensitive to noise and uncorrected background signals as it relies on combining information from brightfield and noisy darkfield (DF) images. In this article we consider the impact of different noise sources in FPM and show that inadequate removal of the DF background signal and associated noise are the predominant cause of artefacts in reconstructed images. We propose a simple solution to FPM background correction and denoising that outperforms existing methods in terms of image quality, speed and simplicity, whilst maintaining high spatial resolution and sharpness of the reconstructed image. Our method takes advantage of the data redundancy in real space within the acquired dataset to boost the signal-to-background ratio in the captured DF images, before optimally suppressing background signal. By incorporating differentially denoised images within the classic FPM iterative phase retrieval algorithm, we show that it is possible to achieve efficient removal of background artefacts without suppression of high frequency information. The method is tested using simulated data and experimental images of thin blood films, bone marrow and liver tissue sections. Our approach is non-parametric, requires no prior knowledge of the noise distribution and can be directly applied to other hardware platforms and reconstruction algorithms making it widely applicable in FPM.
General relation between spatial coherence and absorption
Authors: Tihon D. , Withington S. , Bailly E. , Vest B. , Greffet J.-J.
Published: October 2020

Despite the fact that incandescent sources are usually spatially incoherent, it has been known for some time that a proper design of a thermal source can modify its spatial coherence. A natural question is whether it is possible to extend this analysis to electroluminescence and photoluminescence. A theoretical framework is needed to explore these properties. In this paper, we extend a general coherence-absorption relation valid at equilibrium to two non-equilibrium cases: luminescent bodies and anisothermal bodies. We then use this relation to analyse the differences between the isothermal and anisothermal cases and to study the near-field emission of an electroluminescent source.
Resonant micro-optical gyro based on self-injection locking
Authors: Geng Jingtong , Yang Liu , Zhao Shuhua , Zhang Yonggang
Published: October 2020

We propose the idea and design of a novel resonant micro-optical gyro based on a self-injection locking technique. By enhancing the reciprocity and measuring beat frequency, the sensitivity of gyro is improved effectively, which is usually limited by two main factors: low signal-to-noise ratio and immature signal detecting technique. In addition, a small size distributed feedback semiconductor laser with megahertz linewidth is used for miniaturization, instead of the narrow linewidth and tunable laser in traditional resonant gyros. Sensitivity of this resonant micro-optical gyro depends, in fact, on the accuracy of time measurement. In this paper, theory sensitivity is demonstrated to be at the order of 10−4 deg/h under a 6 KHz modulation frequency.
Suppression of floating image degradation using a mechanical vibration of a dihedral corner reflector array
Authors: Yahagi Yuchi , Fukushima Shogo , Sakaguchi Saki , Naemura Takeshi
Published: October 2020

Dihedral corner reflector arrays (DCRAs) are imaging devices that form real images and are used in a variety of applications, including floating virtual touchscreens and image presentation around physical objects. However, they induce several types of degradations to floating images. It is desirable to suppress these degradations to provide better viewing experiences. This paper proposes a method of suppressing degradations which appear as high-frequency noise by using mechanical vibration. The effects of vibrating the DCRA were confirmed through an analysis of the floating image quality in the frequency domain.
Tunable polarization beam splitter and broadband optical power sensor using hybrid microsphere resonators
Authors: Zhou Han , Ma Ruilong , Zhu Song , Chen Hongyun , Zhang Guangyong , Shi Lei , Zhang Xinliang
Published: October 2020

Based on silica microsphere resonators embedded with iron oxide nanoparticles, we proposed and fabricated an all-optical and continuously tunable polarization beam splitter (PBS), and a broadband optical power sensor (OPS) with high sensitivity. The PBS is realized since the effective refractive indexes of the transverse-electric and transverse-magnetic polarization modes in the microsphere resonator are different. Due to the excellent photothermal effect of iron oxide nanoparticles, we realized the all-optical and continuously tunable PBS based on the hybrid microsphere resonator. A maximum polarization splitting ratio of 20 dB and a tuning range of 5 nm are achieved. Based on this mechanism, the hybrid microsphere resonator can also be used as a broadband OPS. The sensitivity of the OPS is 0.487 nm/mW, 0.477 nm/mW, and 0.398 nm/mW when the probe wavelength is 690 nm, 980 nm, and 1550 nm, respectively. With such good performances, the tunable PBS and the broadband OPS have great potential in applications such as optical routers, switches and filters.
Polyethylenimine-ethoxylated dual interfacial layers for highly efficient and all-solution-processed inverted quantum dot light-emitting diodes
Authors: Lee Woosuk , Kim Boram , Choi Yonghyeok , Chae Heeyeop
Published: October 2020

Inverted quantum dot light-emitting diodes (QLEDs) were fabricated through all-solution processing by sandwiching quantum dot (QD) emitting layers (EMLs) between dual polyethylenimine-ethoxylated (PEIE) layers. First, a PEIE layer as EML protecting layer (EPL) was formed on a QD EML to protect the EML from the hole transport layer (HTL) solvents and to facilitate the formation of a well-organized structure in the all-solution-processed inverted QLEDs. Second, another PEIE layer was introduced as an electron-blocking layer (EBL) on the zinc oxide (ZnO) electron transport layer (ETL) and effectively suppressed the excessive electron injection to the QD EML, thereby enhancing device efficiency.
Shot-to-shot 2D IR spectroscopy at 100 kHz using a Yb laser and custom-designed electronics
Authors: Farrell Kieran M. , Ostrander Josh S. , Jones Andrew C. , Yakami Baichhabi R. , Dicke Sidney S. , Middleton Chris T. , Hamm Peter , Zanni Martin T.
Published: October 2020

The majority of 2D IR spectrometers operate at 1-10 kHz using Ti:Sapphire laser technology. We report a 2D IR spectrometer designed around Yb:KGW laser technology that operates shot-to-shot at 100 kHz. It includes a home-built OPA, a mid-IR pulse shaper, and custom-designed electronics with optional on-chip processing. We report a direct comparison between Yb:KGW and Ti:Sapphire based 2D IR spectrometers. Even though the mid-IR pulse energy is much lower for the Yb:KGW driven system, there is an 8x improvement in signal-to-noise over the 1 kHz Ti:Sapphire driven spectrometer to which it is compared. Experimental data is shown for sub-millimolar concentrations of amides. Advantages and disadvantages of the design are discussed, including thermal background that arises at high repetition rates. This fundamental spectrometer design takes advantage of newly available Yb laser technology in a new way, providing a straightforward means of enhancing sensitivity.