bluuebunny/crossref_metadata_2025 huggingface dataset:
Interface-engineering enhanced light emission from Si/Ge quantum dots
Authors: Ji Zhi-Min , Luo Jun-Wei , Li Shu-Shen
Published: August 2020

Si quantum dots (QDs) have a significant improvement in luminous efficiency compared with bulk Si, achieved by alleviating the forbiddance of no-phonon Γ–Γ radiative transition determined by the law of momentum conservation. Two divergent mechanisms have been proposed to account for the breakdown of momentum conservation in Si QDs, one is due to the space-confinement-induced spread of k-space wave functions associated with Heisenberg uncertainty principle Δr · Δk > 1/2, and the other is due to the interface-effect-induced intervalley mixing between indirect and direct bandgap states. Both mechanisms could cause a small overlap of the electron and hole wave functions in k-space and make vertical transitions allowed, which leads to the zero-phonon light emission. In this work, we unravel the hierarchical relationship between these two primary mechanisms in the process of zero-phonon light emission from indirect bandgap QDs, by performing semiempirical pseudopotential calculation including many-body interaction on the room-temperature luminescent properties of a series of Si, Ge, and Ge/Si core/shell QDs. We show that the space confinement mechanism is dominant in both Si and Ge indirect bandgap QDs, and the interface-induced intervalley coupling mechanism plays a minor role. While in Ge/Si core/shell QDs, the interface-induced intervalley coupling mechanism has a more pronounced contribution to enhanced light emission, implying one can further enhance light emission via engineering interface based on the intervalley coupling mechanism. Given this, we further engineer the Ge QD interface by bringing four motifs of Si/Ge multiple layers from previously inverse designed Si/Ge superlattices and core/shell nanowires for light emitters. We show that two out of four motifs always give rise to two orders of magnitude enhancement in light emission relative to the Ge and Si QDs. We demonstrate that the interface engineering can enhance light emission in indirect bandgap QDs substantially and regulate the intervalley coupling mechanism as the primary factor over the space confinement mechanism in breaking the momentum conservation law.
Half-quantum vortices on c-axis domain walls in chiral p-wave superconductors
Authors: Etter Sarah B , Huang Wen , Sigrist Manfred
Published: August 2020

Chiral superconductors are two-fold degenerate and domains of opposite chirality can form, separated by domain walls. There are indications of such domain formation in the quasi two-dimensional putative chiral p-wave superconductor Sr2RuO4, yet no experiment has explicitly resolved individual domains in this material. In this work, c-axis domain walls lying parallel to the layers in chiral p-wave superconductors are explored from a theoretical point of view. First, using both a phenomenological Ginzburg–Landau and a quasiclassical Bogoliubov-de Gennes approach, a consistent qualitative description of the domain wall structure is obtained. While these domains are decoupled in the isotropic limit, there is a finite coupling in anisotropic systems and the domain wall can be treated as an effective Josephson junction. In the second part, the formation and structure of half-quantum vortices on such c-axis domain walls are discussed.
Calibrating spectrometers for measurements of the spectral irradiance caused by solar radiation
Authors: Schinke Carsten , Pollex Hendrik , Hinken David , Wolf Martin , Bothe Karsten , Kröger Ingo , Nevas Saulius , Winter Stefan
Published: August 2020

Measuring the spectral irradiance of solar radiation is required in many fields of science and technology. In this work, we present an in-depth discussion of the measuring procedure and required corrections for such measurements. We also describe our measurement uncertainty analysis, which is based on a Monte-Carlo procedure in accordance with the Guide to the expression of uncertainty in measurement (JCGM, Paris, 2008). For this purpose, fifteen uncertainty sources are identified, analyzed and described analytically. As a specific application example, we describe the instrumentation and procedure for determining the spectral irradiance of a solar simulator at the ISO/IEC 17 025 accredited solar cell calibration laboratory ISFH CalTeC and the corresponding measurement uncertainty analysis. Moreover, we provide a Python implementation for this calculation along with the paper. We show that for state-of-the-art instrumentation, significant uncertainty contributions arise from the reference lamp (primary calibration standard), stray light and signal-to-noise ratio. If sharp spectral features are present (which is common, e.g. for Xenon lamps), spectral bandwidth and wavelength uncertainty also contribute significantly to the overall uncertainty.
Single-shot incoherent color digital holographic microscopy system with static polarization-sensitive optical elements
Authors: Tahara Tatsuki , Ito Tomoyoshi , Ichihashi Yasuyuki , Oi Ryutaro
Published: August 2020

We propose a digital holographic microscope for the single-shot multicolor three-dimensional (3D) image sensing of specimens illuminated by spatially and temporally incoherent white light. The proposed microscope exploits self-interference, single-shot phase-shifting incoherent digital holography, a polarization-imaging color image sensor, and static polarization-sensitive optical elements to generate two object waves with different curvature radii. The microscope does not require any spatial light modulator or a beam splitter, and can be constructed with a compact single-path optical setup. The color holographic 3D motion picture recording of spatially and temporally incoherent white light at a speed of 10 fps order is experimentally demonstrated with the proposed microscope.
Invited Commentary: Sibling-Comparison Designs, Are They Worth the Effort?
Authors: Frisell Thomas
Published: August 2020

In this issue of the Journal, von Ehrenstein et al. (Am J Epidemiol. 2021;190(5):728–737) add to the large and growing literature on the potentially causal association between prenatal exposure to maternal smoking and neuropsychiatric health. In addition to statewide, prospectively collected data, a particular strength was their ability to perform a sibling-comparison design, contrasting the rate of autism spectrum disorder in siblings discordantly exposed to maternal smoking. Unfortunately, the estimate from the sibling pairs could neither confirm nor refute the conclusions based on the full cohort. Interpretation was hampered by broad confidence limits, and even had power been higher, the authors acknowledge a range of potential biases that would have made it difficult to draw any firm conclusions from a similarity or difference in the sibling-pair estimate and estimate from the full cohort. Was the addition of the sibling comparison actually worth the effort? In this commentary, I will briefly summarize the benefits and limitations of this design, and, with some caveats, argue that its inclusion in the study by von Ehrenstein et al. was indeed a strength and not just an ornamentation.
The optimal discovery procedure for significance analysis of general gene expression studies
Authors: Bass Andrew J , Storey John D
Published: August 2020

Motivation

Analysis of biological data often involves the simultaneous testing of thousands of genes. This requires two key steps: the ranking of genes and the selection of important genes based on a significance threshold. One such testing procedure, called the optimal discovery procedure (ODP), leverages information across different tests to provide an optimal ranking of genes. This approach can lead to substantial improvements in statistical power compared to other methods. However, current applications of the ODP have only been established for simple study designs using microarray technology. Here, we extend this work to the analysis of complex study designs and RNA-sequencing studies.

Results

We apply our extended framework to a static RNA-sequencing study, a longitudinal study, an independent sampling time-series study,and an independent sampling dose–response study. Our method shows improved performance compared to other testing procedures, finding more differentially expressed genes and increasing power for enrichment analysis. Thus, the extended ODP enables a favorable significance analysis of genome-wide gene expression studies.

Availability and implementation

The algorithm is implemented in our freely available R package called edge and can be downloaded at https://www.bioconductor.org/packages/release/bioc/html/edge.html.

Supplementary information

Supplementary data are available at Bioinformatics online.
Finite-time analysis of vector autoregressive models under linear restrictions
Authors: Zheng Yao , Cheng Guang
Published: August 2020

This paper develops a unified finite-time theory for the ordinary least squares estimation of possibly unstable and even slightly explosive vector autoregressive models under linear restrictions, with the applicable region $\rho(A)\leqslant 1+c/n$, where $\rho(A)$ is the spectral radius of the transition matrix $A$ in the var(1) representation, $n$ is the time horizon and $c>0$ is a universal constant. The linear restriction framework encompasses various existing models such as banded/network vector autoregressive models. We show that the restrictions reduce the error bounds via not only the reduced dimensionality, but also a scale factor resembling the asymptotic covariance matrix of the estimator in the fixed-dimensional set-up: as long as the model is correctly specified, this scale factor is decreasing in the number of restrictions. It is revealed that the phase transition from slow to fast error rate regimes is determined by the smallest singular value of $A$, a measure of the least excitable mode of the system. The minimax lower bounds are derived across different regimes. The developed non-asymptotic theory not only bridges the theoretical gap between stable and unstable regimes, but precisely characterizes the effect of restrictions and its interplay with model parameters. Simulations support our theoretical results.
Clarification on “Critical Comments on ‘Assessment of the Thermodynamic Properties of DL-p-Mentha-1,8-diene, 4-isopropyl-1-methylcyclohexene (DL-Limonene) by Inverse Gas Chromatography (IGC)’”
Authors: Farshci Negin , Abbasian Ali
Published: August 2020

A clarification is given regarding recent polemic over our original published study. The author of this polemic has claimed a few issues about the computations and data listed in our work such as choosing the wrong temperature unit and the incorrect calculation of molar heat of vaporization. Here it is elaborated the complete data and computations that are not included in the original paper, and list out also the parameters, which may be the source of difference in reported molar heat of vaporization through inverse gas chromatography methods and other conventional methods. It is showed that there are no wrong calculations or reports of molar heat of vaporization in our published paper.
Attributable Length of Stay, Mortality Risk, and Costs of Bacterial Health Care–Associated Infections in Australia: A Retrospective Case-cohort Study
Authors: Lee X J , Stewardson A J , Worth L J , Graves N , Wozniak T M
Published: August 2020

Background

Unbiased estimates of the health and economic impacts of health care–associated infections (HAIs) are scarce and focus largely on patients with bloodstream infections (BSIs). We sought to estimate the hospital length of stay (LOS), mortality rate, and costs of HAIs and the differential effects on patients with an antimicrobial-resistant infection.

Methods

We conducted a multisite, retrospective case-cohort of all acute-care hospital admissions with a positive culture of 1 of the 5 organisms of interest (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, or Enterococcus faecium) from 1 January 2012 through 30 December 2016. Data linkage was used to generate a data set of statewide hospital admissions and pathology data. Patients with bloodstream, urinary, or respiratory tract infections were included in the analysis and matched to a sample of uninfected patients. We used multistate survival models to generate LOS, and logistic regression to derive mortality estimates.

Results

We matched 20 390 cases to 75 635 uninfected control patients. The overall incidence of infections due to the 5 studied organisms was 116.9 cases per 100 000 patient days, with E. coli urinary tract infections (UTIs) contributing the largest proportion (51 cases per 100 000 patient days). The impact of a UTI on LOS was moderate across the 5 studied pathogens. Resistance significantly increased LOS for patients with third-generation cephalosporin-resistant K. pneumoniae BSIs (extra 4.6 days) and methicillin-resistant S. aureus BSIs (extra 2.9 days). Consequently, the health-care costs of these infections were higher, compared to corresponding drug-sensitive strains.

Conclusions

The health burden remains highest for BSIs; however, UTIs and respiratory tract infections contributed most to the health-care system expenditure.
The Distribution and Spread of Susceptible and Resistant Neisseria gonorrhoeae Across Demographic Groups in a Major Metropolitan Center
Authors: Mortimer Tatum D , Pathela Preeti , Crawley Addie , Rakeman Jennifer L , Lin Ying , Harris Simon R , Blank Susan , Schillinger Julia A , Grad Yonatan H
Published: August 2020

Background

Genomic epidemiology studies of gonorrhea in the United States have primarily focused on national surveillance for antibiotic resistance, and patterns of local transmission between demographic groups of resistant and susceptible strains are unknown.

Methods

We analyzed a convenience sample of genome sequences, antibiotic susceptibility, and patient data from 897 gonococcal isolates cultured at the New York City (NYC) Public Health Laboratory from NYC Department of Health and Mental Hygiene (DOHMH) Sexual Health Clinic (SHC) patients, primarily in 2012–2013. We reconstructed the gonococcal phylogeny, defined transmission clusters using a 10 nonrecombinant single nucleotide polymorphism threshold, tested for clustering of demographic groups, and placed NYC isolates in a global phylogenetic context.

Results

The NYC gonococcal phylogeny reflected global diversity with isolates from 22/23 of the prevalent global lineages (96%). Isolates clustered on the phylogeny by patient sexual behavior (P < .001) and race/ethnicity (P < .001). Minimum inhibitory concentrations were higher across antibiotics in isolates from men who have sex with men compared to heterosexuals (P < .001) and white heterosexuals compared to black heterosexuals (P < .01). In our dataset, all large transmission clusters (≥10 samples) of N. gonorrhoeae were susceptible to ciprofloxacin, ceftriaxone, and azithromycin, and comprised isolates from patients across demographic groups.

Conclusions

All large transmission clusters were susceptible to gonorrhea therapies, suggesting that resistance to empiric therapy was not a main driver of spread, even as risk for resistance varied across demographic groups. Further study of local transmission networks is needed to identify drivers of transmission.
The effects of mandibular osteotomy on maxillary orthodontic tooth movement and bone remodelling in a rat model
Authors: Ji Yingchen , Tang Yi , Wu Qing , Huang Danqing , Zhu Jie , Kang Feiwu
Published: August 2020

Objectives

The accelerated tooth movement phenomenon after orthognathic surgery has been observed. However, the underlying mechanism remains unclear. There is no experimental study showing the effect of orthognathic surgery on orthodontic tooth movement of the opposing jaw. Therefore, the present study aimed at investigating if mandibular osteotomy enhances maxillary tooth movement and bone remodelling.

Materials and methods

Fifty-four male Sprague-Dawley rats were randomly divided into two groups: maxillary tooth movement (TM) and maxillary tooth movement + mandibular surgery (TM + MS). The orthodontic force was delivered to move the left maxillary first molar mesially. The surgical intervention was performed on the left mandible. Microcomputed tomography, histological analysis, enzyme-linked immunosorbent assay, and quantitative real-time polymerase chain reaction were used to assess changes at 3, 7, and 21 days after surgery.

Results

The mandibular osteotomy accelerates the rate of maxillary tooth movement with decreased bone volume fraction on the seventh day. Bone resorption was observed on the third and seventh day after mandibular osteotomy. It was found that serum interleukin-1β level increased significantly in the TM + MS group compared with the TM group, as well as the high expression level of cathepsin K and tumour necrosis factor receptor-associated factor 5 of the orthodontic tooth on the third and seventh day after mandibular osteotomy.

Conclusion

Data from the present study suggested that mandibular osteotomy accelerates maxillary osteoclast activity and post-operative tooth movement, providing evidence for accelerated tooth movement phenomenon after orthognathic surgery.
Mutant huntingtin does not cross the mitochondrial outer membrane
Authors: Hamilton James , Brustovetsky Tatiana , Khanna Rajesh , Brustovetsky Nickolay
Published: August 2020

Mutant huntingtin (mHTT) is associated with mitochondria, but the exact mitochondrial location of mHTT has not been definitively established. Recently, it was reported that mHTT is present in the intermembrane space and inhibits mitochondrial protein import by interacting with TIM23, a major component of mitochondrial protein import machinery, but evidence for functional ramifications were not provided. We assessed mHTT location using synaptic and nonsynaptic mitochondria isolated from brains of YAC128 mice and subjected to alkali treatment or limited trypsin digestion. Mitochondria were purified either with discontinuous Percoll gradient or with anti-TOM22-conjugated iron microbeads. We also used mitochondria isolated from postmortem brain tissues of unaffected individuals and HD patients. Our results demonstrate that mHTT is located on the cytosolic side of the mitochondrial outer membrane (MOM) but does not cross it. This refutes the hypothesis that mHTT may interact with TIM23 and inhibit mitochondrial protein import. The levels of expression of nuclear-encoded, TIM23-transported mitochondrial proteins ACO2, TUFM, IDH3A, CLPP and mitochondrially encoded and synthesized protein mtCO1 were similar in mitochondria from YAC128 mice and their wild-type littermates as well as in mitochondria from postmortem brain tissues of unaffected individuals and HD patients, supporting the lack of deficit in mitochondrial protein import. Regardless of purification technique, mitochondria from YAC128 and WT mice had similar respiratory activities and mitochondrial membrane potentials. Thus, our data argue against mHTT crossing the MOM and entering into the mitochondrial intermembrane space, making it highly unlikely that mHTT interacts with TIM23 and inhibits protein import in intact mitochondria.
Heat production during pulmonary artery sealing with energy vessel-sealing devices in a swine model
Authors: Goudie Eric , Oliveira Ricardo , Thiffault Vicky , Jouquan Adeline , Hadjeres Rachid , Berdugo Jérémie , Ferraro Pasquale , Liberman Moishe
Published: August 2020

OBJECTIVES

Energy vessel-sealing devices are being increasingly utilized to seal pulmonary artery (PA) branches during lobectomy. Heat from these devices can potentially injure surrounding tissues. We evaluated heat production from devices in a live animal model.

METHODS

PA branches were sealed in pigs with 4 energy vessel-sealing devices: 2 ultrasonic (US), 1 advanced bipolar or 1 mixed US and bipolar (mixed) device. Thermocouples were implanted in tissue surrounding the PA branch being sealed to measure tissue temperature. A thermal camera measured the sealing site and the temperatures of the instruments. Pathological analysis was performed on PA stumps to identify thermal damage.

RESULTS

A total of 37 PA branches were sealed in 4 pigs. Maximum tissue heat measured by the thermocouples for the 2 US, advanced bipolar and mixed devices was 42, 39, 42 and 46°C, respectively. The mean tissue temperatures at the site of the sealing measured with the thermal camera were 78, 75, 70 and 82°C (P = 0.834) and the mean instrument blade temperatures were 224, 195, 83 and 170°C (P = 0.000005) for the 2 US, advanced bipolar and mixed devices, respectively. The mean diameter of the region with tissue reaching 60°C or more measured with the thermal camera was between 4 and 6 mm for the 4 devices (P = 0.941). On pathological analysis, PA stumps had either thermal damage on the adventitia and external media (26/37) or transmural damage (11/37) at 1 mm from sealed site.

CONCLUSIONS

A 3-mm safety margin between the instrument blades and vital structures is recommended. Instrument blades can reach high temperatures that may cause tissue damage.
Trends in paediatric central nervous system tumour incidence by global region from 1988 to 2012
Authors: Williams Lindsay A , Hubbard Aubrey K , Scheurer Michael E , Spector Logan G , Poynter Jenny N
Published: August 2020

Background

Central nervous system (CNS) tumours comprise 20% of childhood cancers worldwide. Whether childhood CNS tumour incidence has increased over time across geographic regions remains to be explored.

Methods

We identified CNS cancers in the Cancer in Five Continents (CI5) data and estimated age standardized incidence rates (ASRs; cases/million children) and 95% confidence intervals (95% CI), male-to-female incidence rate ratios (IRR; 95% CI) and average annual percent change in incidence (AAPC; 95% CI) by geographic region for children aged 0–19 years where data were available using Poisson regression and generalized estimating equations (GEE). Cancers included: astrocytic tumours, medulloblastoma, ependymal, oligodendroglial and mixed glioma, glioma of uncertain origin, and other embryonal tumours. Geographic regions were defined using the United Nations geoscheme.

Results

There were 56 468 CNS cancers included in the study. ASRs were highest for astrocytic tumours globally in 2012 (ASR: 5.83; 95% CI: 5.68–5.99). Globally, all cancers exhibited a male excess in incidence. Regionally, only medulloblastoma had a consistently elevated male-to-female IRR at 1.4–2.2. Globally, incidence decreased for astrocytic tumours in GEE models (AAPC: −1.66; 95% CI: −3.04 to −0.26) and increased for medulloblastoma (AAPC 0.66; 95% CI: 0.19–1.14), ependymal tumours (AAPC: 1.49; 95% CI: 1.49; 95%: 0.69–2.30), glioma of uncertain origin (AAPC: 4.76; 95% CI: 1.17–1.14) and other embryonal tumours (AAPC: 3.58; 95% CI: 2.03–5.15). Regional variation in incidence trends was observed. Countries moving from lower to higher Human Development Index (HDI) over time did not appear to drive observed incidence trends.

Conclusions

Epidemiologic and molecular studies on underlying mechanisms for changes in the global incidence of CNS tumours are necessary.
Antibody Responses to Respiratory Syncytial Virus: A Cross-Sectional Serosurveillance Study in the Dutch Population Focusing on Infants Younger Than 2 Years
Authors: Berbers Guy , Mollema Liesbeth , van der Klis Fiona , den Hartog Gerco , Schepp Rutger
Published: August 2020

Background

Respiratory syncytial virus (RSV) generally causes mild disease but can cause severe infections in (premature) infants and elderly adults. Here, we studied RSV-specific antibody concentrations throughout life with emphasis on infants and chronic obstructive pulmonary disease (COPD) patients.

Methods

Sera (N = 2655) from 2 nationwide cross-sectional studies in the Netherlands including individuals aged 0–90 years were analyzed for IgG and IgA antibodies to RSV prefusion F, postfusion F, N, Ga, and Gb proteins and for antibody avidity in 42 COPD patients.

Results

Maternal IgG concentrations declined to age 10–12 months. After the first year of life, approximately 40% of children lacked infection-induced IgA antibodies and may therefore be uninfected. All Dutch children showed serological evidence of RSV infection by age 3 years. Antibody concentrations reached a plateau by age 5–9 years and remains constant throughout life. COPD patients had similar levels and avidity of RSV-specific IgG antibodies compared with age-matched healthy controls.

Conclusions

RSV-IgG antibody patterns throughout life can be used to estimate the degree of immunity acquisition to RSV and to identify groups at increased risk of infection. Seroprevalence of IgA could be a proxy to determine RSV infection in children younger than 1 year.
Rubella Eradication: Not Yet Accomplished, but Entirely Feasible
Authors: Plotkin Stanley A
Published: August 2020

Rubella virus is the most teratogenic virus known to science and is capable of causing large epidemics. The RA 27/3 rubella vaccine, usually combined with measles vaccine, has eliminated rubella and congenital rubella syndrome from much of the world, notably from the Western Hemisphere. Except in immunosuppressed individuals, it is remarkably safe. Together with rubella vaccine strains used in China and Japan, eradication of the rubella virus is possible, indeed more feasible than eradication of measles or mumps.
Smart hospital infrastructure: geomagnetic in-hospital medical worker tracking
Authors: Yamashita Keiko , Oyama Shintaro , Otani Tomohiro , Yamashita Satoshi , Furukawa Taiki , Kobayashi Daisuke , Sato Kikue , Sugano Aki , Funada Chiaki , Mori Kensaku , Ishiguro Naoki , Shiratori Yoshimune
Published: August 2020

Purpose

Location visualization is essential for locating people/objects, improving efficiency, and preventing accidents. In hospitals, Wi-Fi, Bluetooth low energy (BLE) Beacon, indoor messaging system, and similar methods have generally been used for tracking, with Wi-Fi and BLE being the most common. Recently, nurses are increasingly using mobile devices, such as smartphones and tablets, while shifting. The accuracy when using Wi-Fi or BLE may be affected by interference or multipath propagation. In this research, we evaluated the positioning accuracy of geomagnetic indoor positioning in hospitals.

Materials and Methods

We compared the position measurement accuracy of a geomagnetic method alone, Wi-Fi alone, BLE beacons alone, geomagnetic plus Wi-Fi, and geomagnetic plus BLE in a general inpatient ward, using a geomagnetic positioning algorithm by GiPStech. The existing Wi-Fi infrastructure was used, and 20 additional BLE beacons were installed. Our first experiment compared these methods’ accuracy for 8 test routes, while the second experiment verified a combined geomagnetic/BLE beacon method using 3 routes based on actual daily activities.

Results

The experimental results demonstrated that the most accurate method was geomagnetic/BLE, followed by geomagnetic/Wi-Fi, and then geomagnetic alone.

Discussion

The geomagnetic method’s positioning accuracy varied widely, but combining it with BLE beacons reduced the average position error to approximately 1.2 m, and the positioning accuracy could be improved further. We believe this could effectively target humans (patients) where errors of up to 3 m can generally be tolerated.

Conclusion

In conjunction with BLE beacons, geomagnetic positioning could be sufficiently effective for many in-hospital localization tasks.
Secure traveling salesman problem with intelligent transport systems features
Authors: Crişan Gloria Cerasela , Pintea Camelia-M , Calinescu Anisoara , Pop Sitar Corina , Pop Petrică C
Published: August 2020

Meeting the security requests in transportation is nowadays a must. The intelligent transport systems (ITSs) represent the support for addressing such a challenge, due to their ability to make real-time adaptive decisions. We propose a new variant of the travelling salesman problem (TSP) integrating security constraints inspired from ITSs. This optimization problem is called the secure TSP and considers a set of security constraints on its integer variables. Similarities with fuzzy logic are presented alongside the mathematical model of the introduced TSP variant.
An atypical case of necrotizing fasciitis secondary to perforated cecal cancer
Authors: Heidelberg Laura S , Pettke Erica N , Wagner Teresa , Angotti Lauren
Published: August 2020

Necrotizing fasciitis is an aggressive, life threatening soft tissue infection that requires high index of suspicion for diagnosis. Diagnosis is clinical with management including broad spectrum antibiotics and emergent operative debridement. The majority of cases are secondary to underlying medical processes, local tissue damage, abscess, or inciting procedure, with a paucity of data correlating causation with colon cancer. We describe the case of an 84-year-old man presenting with sepsis of unknown origin who was diagnosed with an atypical presentation of necrotizing fasciitis secondary to a perforated cecal malignancy. His case is unique in that a less virulent polymicrobial infection was likely involved as he initially improved with conservative management alone. He ultimately declined and expired secondary to overwhelming sepsis from his infection. This case highlights the importance of maintaining a high index of suspicion for necrotizing infection and considerations for alternative etiologies of infection including perforated malignancies.
Negotiating upstream petroleum granting instrument terms with a state—what to do when the spider meets the fly
Authors: Roberts Peter
Published: August 2020

This article considers the key considerations to be borne in mind by an investor when negotiating the terms of an upstream petroleum granting instrument with a host government. In this article the term ‘granting instrument’ is used generically as a single term for ease of reference, intended to encompass all the different forms of petroleum concession, licence, contract or permit, but the article’s analysis is focused on the terms of a production sharing contract (PSC) simply because the PSC is the form of granting instrument which by far is the most widely used worldwide today for petroleum exploration and production. Despite this focus, many of the terms of the PSC which are considered in this article will also be relevant to other forms of petroleum granting instrument.
ABF3 enhances drought tolerance via promoting ABA-induced stomatal closure by directly regulatingADF5inPopulus euphratica
Authors: Yang Yanli , Li Hui-Guang , Wang Jie , Wang Hou-Ling , He Fang , Su Yanyan , Zhang Ying , Feng Cong-Hua , Niu Mengxue , Li Zhonghai , Liu Chao , Yin Weilun , Xia Xinli
Published: August 2020

Water availability is a main limiting factor for plant growth, development, and distribution throughout the world. Stomatal movement mediated by abscisic acid (ABA) is particularly important for drought adaptation, but the molecular mechanisms in trees are largely unclear. Here, we isolated an ABA-responsive element binding factor, PeABF3, in Populus euphratica. PeABF3 was preferentially expressed in the xylem and young leaves, and was induced by dehydration and ABA treatments. PeABF3 showed transactivation activity and was located in the nucleus. To study its functional mechanism in poplar responsive to drought stress, transgenic triploid white poplars (Populus tomentosa ‘YiXianCiZhu B385’) overexpressing PeABF3 were generated. PeABF3 overexpression significantly enhanced stomatal sensitivity to exogenous ABA. When subjected to drought stress, PeABF3 overexpression maintained higher photosynthetic activity and promoted cell membrane integrity, resulting in increased water-use efficiency and enhanced drought tolerance compared with wild-type controls. Moreover, a yeast one-hybrid assay and an electrophoretic mobility shift assay revealed that PeABF3 activated the expression of Actin-Depolymerizing Factor-5 (PeADF5) by directly binding to its promoter, promoting actin cytoskeleton remodeling and stomatal closure in poplar under drought stress. Taken together, our results indicate that PeABF3 enhances drought tolerance via promoting ABA-induced stomatal closure by directly regulating PeADF5 expression.
N-acyl homoserine lactone-mediated modulation of plant growth and defense against Pseudoperonospora cubensis in cucumber
Authors: Pazarlar Sercan , Cetinkaya Nedim , Bor Melike , Kara Recep Serdar
Published: August 2020

N-acyl-homoserine lactones (AHLs), a well-described group of quorum sensing molecules, may modulate plant defense responses and plant growth. However, there is limited knowledge regarding the defense responses of non-model crops to AHLs and the mechanism of action responsible for the modulation of defense responses against microbial pathogens. In the present study, long-chain N-3-oxo-tetradecanoyl-l-homoserine lactone (oxo-C14-HSL) was shown to have a distinct potential to prime cucumber for enhanced defense responses against the biotrophic oomycete pathogen Pseudoperonospora cubensis and the hemibiotrophic bacterium Pseudomonas syringae pv. lachrymans. We provide evidence that AHL-mediated enhanced defense against downy mildew disease is based on cell wall reinforcement by lignin and callose deposition, the activation of defense-related enzymes (peroxidase, β-1,3-glucanase, phenylalanine ammonia-lyase), and the accumulation of reactive oxygen species (hydrogen peroxide, superoxide) and phenolic compounds. Quantitative analysis of salicylic acid and jasmonic acid, and transcriptional analysis of several of genes associated with these phytohormones, revealed that defense priming with oxo-C14-HSL is commonly regulated by the salicylic acid signaling pathway. We also show that treatment with short- (N-hexanoyl-l-homoserine lactone) and medium-chain (N-3-oxo-decanoyl-l-homoserine lactone) AHLs promoted primary root elongation and modified root architecture, respectively, resulting in enhanced plant growth.
Natural variation and genomic prediction of growth, physiological traits, and nitrogen-use efficiency in perennial ryegrass under low-nitrogen stress
Authors: Zhao Xiongwei , Nie Gang , Yao Yanyu , Ji Zhongjie , Gao Jianhua , Wang Xingchun , Jiang Yiwei
Published: August 2020

Genomic prediction of nitrogen-use efficiency (NUE) has not previously been studied in perennial grass species exposed to low-N stress. Here, we conducted a genomic prediction of physiological traits and NUE in 184 global accessions of perennial ryegrass (Lolium perenne) in response to a normal (7.5 mM) and low (0.75 mM) supply of N. After 21 d of treatment under greenhouse conditions, significant variations in plant height increment (ΔHT), leaf fresh weight (LFW), leaf dry weight (LDW), chlorophyll index (Chl), chlorophyll fluorescence, leaf N and carbon (C) contents, C/N ratio, and NUE were observed in accessions , but to a greater extent under low-N stress. Six genomic prediction models were applied to the data, namely the Bayesian method Bayes C, Bayesian LASSO, Bayesian Ridge Regression, Ridge Regression-Best Linear Unbiased Prediction, Reproducing Kernel Hilbert Spaces, and randomForest. These models produced similar prediction accuracy of traits within the normal or low-N treatments, but the accuracy differed between the two treatments. ΔHT, LFW, LDW, and C were predicted slightly better under normal N with a mean Pearson r-value of 0.26, compared with r=0.22 under low N, while the prediction accuracies for Chl, N, C/N, and NUE were significantly improved under low-N stress with a mean r=0.45, compared with r=0.26 under normal N. The population panel contained three population structures, which generally had no effect on prediction accuracy. The moderate prediction accuracies obtained for N, C, and NUE under low-N stress are promising, and suggest a feasible means by which germplasm might be initially assessed for further detailed studies in breeding programs.
Powerful ionized gas outflows in the interacting radio galaxy 4C+29.30
Authors: Couto Guilherme S , Storchi-Bergmann Thaisa , Siemiginowska Aneta , Riffel Rogemar A , Morganti Raffaella
Published: August 2020

We investigate the ionized gas excitation and kinematics in the inner $4.3\, \times \, 6.2$ kpc2 of the merger radio galaxy 4C+29.30. Using optical integral field spectroscopy with the Gemini North Telescope, we present flux distributions, line-ratio maps, peak velocities and velocity dispersion maps as well as channel maps with a spatial resolution of $\approx\! 955\,$ pc. We observe high blueshifts of up to $\sim\! -650\,$$\rm km\, s^{-1}$ in a region ∼1 arcsec south of the nucleus (the southern knot – SK), which also presents high velocity dispersions ($\sim\! 250\,$$\rm km\, s^{-1}$), which we attribute to an outflow. A possible redshifted counterpart is observed north from the nucleus (the northern knot – NK). We propose that these regions correspond to a bipolar outflow possibly due to the interaction of the radio jet with the ambient gas. We estimate a total ionized gas mass outflow rate of $\dot{M}_{\mathrm{ out}} = 25.4 ^{+11.5 }_{ -7.5}\,$ M⊙ yr−1with a kinetic power of $\dot{E} = 8.1 ^{+10.7 }_{ -4.0} \times 10^{42}\,$ erg s−1, which represents $5.8 ^{+7.6 }_{ -2.9} {{\ \rm per\ cent}}$ of the active galactic nucleus (AGN) bolometric luminosity. These values are higher than usually observed in nearby active galaxies with the same bolometric luminosities and could imply a significant impact of the outflows in the evolution of the host galaxy. The excitation is higher in the NK – that correlates with extended X-ray emission, indicating the presence of hotter gas – than in the SK, supporting a scenario in which an obscuring dust lane is blocking part of the AGN radiation to reach the southern region of the galaxy.
Exploring universality in neutron star mergers
Authors: Chakravarti Kabir , Andersson Nils
Published: August 2020

We explore the correlation between the pre-merger tidal deformability and the post-merger remnant oscillations seen in numerical simulations of neutron star binaries, with the aim of understanding to what extent the physics support the existence of such a relation. We consider the impact of thermal and rotational effects and argue that the proposed relation does, indeed, make sense and provide simple arguments that help explain the result.
Solution to the debris disc mass problem: planetesimals are born small?
Authors: Krivov Alexander V , Wyatt Mark C
Published: August 2020

Debris belts on the periphery of planetary systems, encompassing the region occupied by planetary orbits, are massive analogues of the Solar system’s Kuiper belt. They are detected by thermal emission of dust released in collisions amongst directly unobservable larger bodies that carry most of the debris disc mass. We estimate the total mass of the discs by extrapolating up the mass of emitting dust with the help of collisional cascade models. The resulting mass of bright debris discs appears to be unrealistically large, exceeding the mass of solids available in the systems at the preceding protoplanetary stage. We discuss this ‘mass problem’ in detail and investigate possible solutions to it. These include uncertainties in the dust opacity and planetesimal strength, variation of the bulk density with size, steepening of the size distribution by damping processes, the role of the unknown ‘collisional age’ of the discs, and dust production in recent giant impacts. While we cannot rule out the possibility that a combination of these might help, we argue that the easiest solution would be to assume that planetesimals in systems with bright debris discs were ‘born small’, with sizes in the kilometre range, especially at large distances from the stars. This conclusion would necessitate revisions to the existing planetesimal formation models, and may have a range of implications for planet formation. We also discuss potential tests to constrain the largest planetesimal sizes and debris disc masses.
Validating N-body code chrono for granular DEM simulations in reduced-gravity environments
Authors: Sunday Cecily , Murdoch Naomi , Tardivel Simon , Schwartz Stephen R , Michel Patrick
Published: August 2020

The Discrete Element Method (DEM) is frequently used to model complex granular systems and to augment the knowledge that we obtain through theory, experimentation, and real-world observations. Numerical simulations are a particularly powerful tool for studying the regolith-covered surfaces of asteroids, comets, and small moons, where reduced-gravity environments produce ill-defined flow behaviours. In this work, we present a method for validating soft-sphere DEM codes for both terrestrial and small-body granular environments. The open-source code chrono is modified and evaluated first with a series of simple two-body-collision tests, and then, with a set of piling and tumbler tests. In the piling tests, we vary the coefficient of rolling friction to calibrate the simulations against experiments with 1 mm glass beads. Then, we use the friction coefficient to model the flow of 1 mm glass beads in a rotating drum, using a drum configuration from a previous experimental study. We measure the dynamic angle of repose, the flowing layer thickness, and the flowing layer velocity for tests with different particle sizes, contact force models, coefficients of rolling friction, cohesion levels, drum rotation speeds, and gravity levels. The tests show that the same flow patterns can be observed at the Earth and reduced-gravity levels if the drum rotation speed and the gravity level are set according to the dimensionless parameter known as the Froude number. chrono is successfully validated against known flow behaviours at different gravity and cohesion levels, and will be used to study small-body regolith dynamics in future works.
The dynamical state of Abell 2399: a bullet-like cluster
Authors: Lourenço Ana C C , Lopes P A A , Laganá T F , Nascimento R S , Machado R E G , Moura M T , Jaffé Y L , Ribeiro A L , Vulcani B , Moretti A , Riguccini L A
Published: August 2020

While there are many ways to identify substructures in galaxy clusters using different wavelengths, each technique has its own caveat. In this paper, we conduct a detailed substructure search and dynamical state characterization of Abell 2399, a galaxy cluster in the local Universe (z ∼ 0.0579), by performing a multiwavelength analysis and testing the results through hydrodynamical simulations. In particular, we apply a Gaussian mixture model to the spectroscopic data from SDSS, WINGS, and OmegaWINGS Surveys to identify substructures. We further use public XMM–Newton data to investigate the intracluster medium (ICM) thermal properties, creating temperature, metallicity, entropy, and pressure maps. Finally, we run hydrodynamical simulations to constrain the merger stage of this system. The ICM is very asymmetrical and has regions of temperature and pressure enhancement that evidence a recent merging process. The optical substructure analysis retrieves the two main X-ray concentrations. The temperature, entropy, and pressure are smaller in the secondary clump than in the main clump. On the other hand, its metallicity is considerably higher. This result can be explained by the scenario found by the hydrodynamical simulations where the secondary clump passed very near to the centre of the main cluster possibly causing the galaxies of that region to release more metals through the increase of ram-pressure stripping.
Are the spiral arms in the MWC 758 protoplanetary disc driven by a companion inside the cavity?
Authors: Calcino Josh , Christiaens Valentin , Price Daniel J , Pinte Christophe , Davis Tamara M , van der Marel Nienke , Cuello Nicolás
Published: August 2020

Spiral arms in protoplanetary discs are thought to be linked to the presence of companions. We test the hypothesis that the double spiral arm morphology observed in the transition disc MWC 758 can be generated by an ≈10MJup companion on an eccentric orbit internal to the spiral arms. Previous studies on MWC 758 have assumed an external companion. We compare simulated observations from three-dimensional hydrodynamics simulations of disc–companion interaction to scattered light, infrared and CO molecular line observations, taking into account observational biases. The inner companion hypothesis is found to explain the double spiral arms, as well as several additional features seen in MWC 758 – the arc in the north-west, substructures inside the spiral arms, the cavity in CO isotopologues, and the twist in the kinematics. Testable predictions include detection of fainter spiral structure, detection of a point source south-southeast of the primary, and proper motion of the spiral arms.
AGN and star formation properties of inside–out assembled galaxy candidates at z < 0.1
Authors: Zewdie Dejene , Pović Mirjana , Aravena Manuel , Assef Roberto J , Gaulle Asrate
Published: August 2020

We study a sample of 48 127 galaxies selected from the SDSS MPA-JHU catalogue, with log M⋆/M⊙ = 10.73−11.03 and z < 0.1. Local galaxies in this stellar mass range have been shown to have systematically shorter assembly times within their inner regions (<0.5 R50) when compared to that of the galaxy as a whole, contrary to lower or higher mass galaxies that show consistent assembly times at all radii. Hence, we refer to these galaxies as Inside-Out Assembled Galaxy (IOAG) candidates. We find that the majority of IOAG candidates with well-detected emission lines are classified as either active galactic nucleus (AGN; 40 per cent) or composite (40 per cent) in the BPT (Baldwin, Phillips & Terlevich) diagram. We also find that the majority of our sources are located below the main sequence of star formation, and within the green valley or red sequence. Most BPT-classified star-forming IOAG candidates have spiral morphologies and are in the main sequence, whereas Seyfert 2 and composites have mostly spiral morphologies but quiescent star formation rates (SFRs). We argue that a high fraction of IOAG candidates seem to be in the process of quenching, moving from the blue cloud to the red sequence. Those classified as AGN have systematically lower SFRs than star-forming galaxies, suggesting that AGN activity may be related to this quenching. However, the spiral morphology of these galaxies remains in place, suggesting that the central star formation is suppressed before the morphological transformation occurs.
What does FRB light-curve variability tell us about the emission mechanism?
Authors: Beniamini Paz , Kumar Pawan
Published: August 2020

A few fast radio bursts’ (FRBs) light curves have exhibited large intrinsic modulations of their flux on extremely short ($t_{\rm r}\sim 10\, \mu$s) time-scales, compared to pulse durations (tFRB ∼ 1 ms). Light-curve variability time-scales, the small ratio of rise time of the flux to pulse duration, and the spectro-temporal correlations in the data constrain the compactness of the source and the mechanism responsible for the powerful radio emission. The constraints are strongest when radiation is produced far (≳1010 cm) from the compact object. We describe different physical set-ups that can account for the observed tr/tFRB ≪ 1 despite having large emission radii. The result is either a significant reduction in the radio production efficiency or distinct light-curve features that could be searched for in observed data. For the same class of models, we also show that due to high-latitude emission, if a flux f1(ν1) is observed at t1 then at a lower frequency ν2 < ν1 the flux should be at least (ν2/ν1)2f1 at a slightly later time (t2 = t1ν1/ν2) independent of the duration and spectrum of the emission in the comoving frame. These features can be tested, once light-curve modulations due to scintillation are accounted for. We provide the time-scales and coherence bandwidths of the latter for a range of possibilities regarding the physical screens and the scintillation regime. Finally, if future highly resolved FRB light curves are shown to have intrinsic variability extending down to ${\sim}\mu$s time-scales, this will provide strong evidence in favour of magnetospheric models.