bluuebunny/crossref_metadata_2025 huggingface dataset:
Mineral prospectivity mapping using a VNet convolutional neural network
Authors: McMillan Michael , Haber Eldad , Peters Bas , Fohring Jennifer
Published: February 2021

Major mineral discoveries have declined in recent decades, and the natural resource industry is in the process of adapting and incorporating novel technologies such as machine learning and artificial intelligence to help guide the next generation of exploration. One such development is an artificial intelligence architecture called VNet that uses deep learning and convolutional neural networks. This method is designed specifically for use with geoscience data and is suitable for a multitude of exploration applications. One such application is mineral prospectivity in which the machine is tasked with identifying the complex pattern between many layers of geoscience data and a particular commodity of interest, such as gold. The VNet algorithm is designed to recognize patterns at different spatial scales, which lends itself well to the mineral prospectivity problem of there often being local and regional trends that affect where mineralization occurs. We test this approach on an orogenic gold greenstone belt setting in the Canadian Arctic where the algorithm uses gold values from sparse drill holes for training purposes to predict gold mineralization elsewhere in the region. The prospectivity results highlight new target areas, and one such target was followed up with a direct-current induced polarization survey. A chargeability anomaly was discovered wherein the VNet had predicted gold mineralization, and subsequent drilling encountered a 6 g/t Au intercept within 10 m of drilling that averaged more than 1.0 g/t Au. Although most of the prospectivity targets generated from VNet were not drill tested, this first intercept helps validate the approach. We believe this method can help maximize the use of existing geoscience data for successful and efficient exploration programs in the future.
Use of novel 3D seismic technology and machine learning for pothole detection, characterization, and classification — Case study in the Bushveld Complex (South Africa)
Authors: Zhang Steven E. , Sehoole Lebogang , Manzi Musa S. D. , Bourdeau Julie E. , Nwaila Glen T.
Published: February 2021

We demonstrate that integrating 3D reflection seismics with machine learning (ML) can bring many benefits for the future development of the mining industry. We use a serial integration of reflection seismics, which identifies economic horizon-depression structures known as potholes within the western Bushveld Complex. Thereafter, agglomerative clustering is applied to the resulting data, using features engineered from the physical characteristics of the potholes. Our results indicate that potholes can be divided into several classes based on characteristic features; e.g., large potholes are substantially less steep than small potholes. Furthermore, we model this empirical relationship and show that it can be used to predict average sizes of potholes given their typical in-mine exposures. We also demonstrate that pothole formation is likely to have been initiated depth-wise, followed by lateral increases in size. Lastly, we demonstrate that our serial application of seismically based data generation and ML-based data analytics is a viable alternative to conventional geostastistical analysis, especially for the classification, prediction, and modeling of geologic structures such as potholes.
Sparse 3D seismic and magnetic imaging at Escondida porphyry copper mine, Chile
Authors: Schijns Heather , Madero Gabriel , Bugueño Jorge , Salazar Andres , Grant Todd
Published: February 2021

Seismic is often inferred to be synonymous with high cost. In a mineral environment, it is typically assumed to be viable only for mining operations or brownfield exploration. For greenfield exploration, other geophysical and geochemical/lithogeochemical methods are usually preferred, due in part to their affordability. We show results of a low-cost seismic survey over the Escondida porphyry copper deposit. The results show that low-cost 3D acquisition can improve structural understanding of established porphyry deposits and that there is potential for 3D seismic to be applied in brownfield and perhaps even greenfield exploration. The sparse 3D seismic reflection survey acquired at Escondida illuminates the structural setting and images stock genetically related to the Escondida intrusive complex at depth. The seismic results are compared to a magnetization vector inversion calculated from a regional airborne survey. This illustrates the potential for jointly utilizing the two methods to identify and prioritize anomalies for targeted drilling-based follow-up in exploration settings.
The geophysical response of the Goldrush-Fourmile orebody and implications for camp-scale Carlin-type deposit exploration, Cortez District, Nevada
Authors: Sampson Lee M. , Williams Nicholas C.
Published: February 2021

Since discovery of the Goldrush and Fourmile deposits, numerous geophysical surveys have been acquired over the footprint of mineralization and surrounding areas to focus exploration. The Goldrush-Fourmile system extends more than 7 km in strike length and averages approximately 300 m wide. Most of the orebody lies more than 300 m below ground surface and continues to depths of more than 900 m. Direct detection of the ore system using geophysical tools is impeded by several factors. The system is relatively flat lying and sits in the hinge of a doubly plunging anticline. This gives the shallowest zones a very small lateral footprint. The ore consists of thin strata-bound zones of silica-sulfide mineralization with a tight alteration selvage. Structural controls along faults are limited, with only small displacements. Strong petrophysical contrasts exist between unaltered rock units. Finally, the terrain is rugged. Resistivity inversions of airborne electromagnetic data show that mineralization sits within a complex zone of resistivity responses. Close to intrusions, the host stratigraphy is resistive. Away from intrusions, the same stratigraphic units show highly variable but commonly very low resistivities. This suggests the possibility of redistribution of carbon around intrusions during premineralization metasomatism. Within the orebody, sulfide content increases conductivity within individual formations related to the distribution of fine-grained sooty pyrite. The geometry of the Red Hill Anticline is imaged as a positive density contrast in the observed gravity and geologically constrained gravity inversions. The positive density contrast represents the gross geophysical signature of denser carbonates within the Paleozoic stratigraphy. Magnetic surveys are crucial for mapping the distribution of igneous rocks and potentially hornfelsed sedimentary rocks. The challenges associated with exploring for deeply buried Carlin mineralization notwithstanding, the application of innovative geophysical tools tuned to assess specific geologic questions, combined with best-practice geologic and geochemical modeling, is helping drive exploration for additional Carlin-type mineralization across the Cortez District.
Geophysical electromagnetics: A retrospective, DISC 2017, and a look forward
Authors: Oldenburg Douglas W. , Heagy Lindsey J. , Kang Seogi
Published: February 2021

Geophysical electromagnetics (EM) plays an important role in mineral exploration and is increasingly being used to help solve other problems of relevance to society. In this article we reflect, from our perspective at the University of British Columbia, on the development of EM geophysics over the years, on our attempts to enhance understanding of EM geophysics, and on its visibility and usefulness to the community. The availability of open-source resources and a shift within the EM community toward collaborative practices for sharing and creating software and educational resources have been drivers of progress toward these goals. In this article, we provide background about this trajectory and discuss how the SEG Distinguished Instructor Short Course was a catalyst in our development of software and resources as well as in our broader goal of creating more collaborative connections within the EM community.
Seismic imaging of a near-vertical vein using controlled-source seismic interferometry
Authors: Dias Kriselle , Hurich Charles , Deemer Sharon
Published: February 2021

New methodologies for narrow-vein mining are making thin, steeply dipping mineralized veins economically viable mining targets. Drilling is the normal method for delineation and resource evaluation prior to mining. However, for the evaluation of narrow veins, significant drilling of barren rock is required. Controlled-source seismic interferometry has the potential to significantly decrease the costs of target delineation by providing high-resolution seismic images of thin, steeply dipping mineralized veins. We present a case study that employs seismic interferometry in conjunction with a walkaway vertical seismic profiling survey to image a thin (0.5–4 m), steeply dipping barite vein. The footprint of the seismic data acquisition is relatively small and compatible with operations in areas with limited access (e.g., mining camps). The technique requires some care with experimental design and data processing, but it is clearly demonstrated to produce a high-resolution seismic image. Furthermore, we demonstrate that inversion of the depth-migrated image can be used to quantify vein thickness and provide direct information for resource evaluation and reserve estimation.
International Geomechanics Symposium a success
Authors: Han Gang , Mansour Abdulaziz , Badri Mohammed , Mahmood Tariq
Published: February 2021

As the oil and gas industry is striving for efficiency, cost reduction, and improved performance across the value chain, integrated workflows that combine various disciplines into subsurface drilling, characterization, and production have become increasingly important. Geomechanics is gaining stronger ground as a vital tool in modeling, simulation, and operations. Given its importance, the American Rock Mechanics Association, Dhahran Geoscience Society, and Society of Exploration Geophysicists cohosted the International Geomechanics Symposium. The event was conducted virtually 3–5 November 2020.
Impact of Organ Function–Based Clinical Trial Eligibility Criteria in Patients With Diffuse Large B-Cell Lymphoma: Who Gets Left Behind?
Authors: Khurana Arushi , Mwangi Raphael , Nowakowski Grzegorz S. , Habermann Thomas M. , Ansell Stephen M. , LaPlant Betsy R. , Link Brian K. , Cerhan James R. , Maurer Matthew J. , Witzig Thomas E.
Published: February 2021

PURPOSE

Exclusion of patients needing urgent treatment or requiring novel biomarkers before enrollment has impacted the ability to enroll real-world patients in frontline trials of diffuse large B-cell lymphoma (DLBCL). The impact of baseline organ function–based eligibility criteria on this effect and clinical trial exclusion is less well-understood.

METHODS

Consecutive patients with newly diagnosed lymphoma were enrolled from 2002 to 2015 into the Molecular Epidemiology Resource (MER) of the University of Iowa and Mayo Clinic Lymphoma Specialized Program of Research Excellence. The current analysis includes 1,265 patients with DLBCL receiving standard immunochemotherapy. Organ function parameters were identified from criteria for hemoglobin, absolute neutrophil count, platelet count, creatinine clearance, and bilirubin, as reported in frontline DLBCL trials. Abstracted laboratory values from MER were used to determine the percent (%) of patients excluded. Outcomes and cause-of-death analyses comparing ineligible and eligible groups in MER were conducted. An interactive online tool was developed to estimate exclusions based on organ function for future trial design.

RESULTS

Between 9% and 24% of MER patients with DLBCL receiving standard immunochemotherapy were excluded on the basis of baseline organ function alone. Ineligible patients based on organ function had significantly inferior event-free survival (hazard ratios, 1.67-2.16), overall survival (hazard ratios, 1.87-2.56), and event-free survival at 24 months (odds ratio, 1.71-2.16). Ineligible patients were more likely to die from lymphoma progression than increased therapy-related complications.

CONCLUSION

Current national and international trials exclude up to 24% of patients from participation on the basis of organ function alone. A significant difference in the outcomes, notably lymphoma-related death, suggests issues with generalization and potential exclusion of high-risk patients. These data will help future clinical trial development and meet US Food and Drug Administration and ASCO recommendations to increase trial accrual.
Impact of the COVID-19 Pandemic Surge on Radiation Treatment: Report From a Multicenter New York Area Institution
Authors: Teckie Sewit , Andrews Janna Zeola , Chen William Chun-Ying , Goenka Anuj , Koffler Daniel , Adair Nilda , Potters Louis
Published: February 2021

PURPOSE:

During the COVID-19 surge months of March and April 2020, our New York multicenter health system experienced an influx of cases with COVID-19. We sought to study the impact of the surge period on patients with cancer prescribed radiation treatment (RT).

METHODS:

We reviewed our secure departmental quality assurance database for all patients who underwent RT planning simulations from March 6, 2020, through April 30, 2020. A priority level between 1 and 3 was prospectively assigned to each case based on faculty consensus to determine which patients required immediate RT. In May 2020, each faculty physician again retrospectively reviewed their patients from the database and provided additional commentary on how the COVID-19 pandemic had affected each patient's care. All statistics are descriptive.

RESULTS:

A total of 412 RT courses in 406 unique patients were simulated for linear accelerator–based external beam RT. The median age was 66 years. Treatment intent was curative in 70.6% and palliative in 29.4%. Of the 412 cases, 66.7% were priority 1, 25% priority 2, and 7.8% priority 3. Two hundred thirty-nine cases (58%) underwent standard-of-care diagnosis, workup, and treatment plan. Seventeen patients (4.1%) electively canceled their RT, and 17 others (4.1%) electively delayed RT start. Thirty-four (8.3%) were prescribed hypofractionation to shorten their RT course, and 22 (5.3%) had a change in modality. Incomplete or delayed workup was identified in 19 cases (4.6%).

CONCLUSION:

The COVID-19 pandemic surge resulted in 42% of our patients having a non–standard-of-care pathway. This outcome demonstrates a significant impact of the COVID-19 crisis on routine cancer care.
Dosimetric impact of random spot positioning errors in intensity modulated proton therapy plans of small and large volume tumors
Authors: Arjunan Manikandan , Krishnan Ganapathy , Sharma Dayananda Shamurailatpam , M P Noufal , Patro Kartikeshwar C , Thiyagarajan Rajesh , Srinivas Chilukuri , Jalali Rakesh
Published: February 2021

Objective

To study dosimetric impact of random spot positioning errors on the clinical pencil beam scanning proton therapy plans.

Methods and materials

IMPT plans of 10 patients who underwent proton therapy for tumors in brain or pelvic regions representing small and large volumes, respectively, were included in the study. Spot positioning errors of 1 mm, −1 mm or ±1 mm were introduced in these clinical plans by modifying the geometrical co-ordinates of proton spots using a script in the MATLAB programming environment. Positioning errors were simulated to certain numbers of (20%, 40%, 60%, 80%) randomly chosen spots in each layer of these treatment plans. Treatment plans with simulated errors were then imported back to the Raystation (Version 7) treatment planning system and the resultant dose distribution was calculated using Monte-Carlo dose calculation algorithm.

Dosimetric plan evaluation parameters for target and critical organs of nominal treatment plans delivered for clinical treatments were compared with that of positioning error simulated treatment plans. For targets, D95% and D2% were used for the analysis. Dose received by optic nerve, chiasm, brainstem, rectum, sigmoid, and bowel were analyzed using relevant plan evaluation parameters depending on the critical structure. In case of intracranial lesions, the dose received by 0.03 cm3 volume (D0.03 cm3) was analyzed for optic nerve, chiasm and brainstem. In rectum, the volume of it receiving a dose of 65 Gy(RBE) (V65) and 40 Gy(RBE) (V40) were compared between the nominal and error introduced plans. Similarly, V65 and V63 were analyzed for Sigmoid and V50 and V15 were analyzed for bowel.

Results

The maximum dose variation in PTV D95% (1.88 %) was observed in a brain plan in which the target volume was the smallest (2.7 cm3) among all 10 plans included in the study. This variation in D95% drops down to 0.3% for a sacral chordoma plan in which the PTV volume is significantly higher at 672 cm3. The maximum difference in OARs in terms of absolute dose (D0.03 cm3) was found in left optic nerve (9.81%) and the minimum difference was observed in brainstem (2.48%). Overall, the magnitude of dose errors in chordoma plans were less significant in comparison to brain plans.

Conclusion

The dosimetric impact of different error scenarios in spot positioning becomes more prominent for treatment plans involving smaller target volume compared to plans involving larger target volumes.

Advances in knowledge

Provides information on the dosimetric impact of various possible spot positioning errors and its dependence on the tumor volume in intensity modulated proton therapy.
Scalable Data Fusion with Selection Correction: An Application to Customer Base Analysis
Authors: McCarthy Daniel Minh , Oblander Elliot Shin
Published: February 2021

A computationally scalable, statistically efficient aggregate-disaggregate data fusion method that corrects for selection bias is applied to model customer relationship dynamics at a subscription-based firm.
Roadblock to Innovation: The Role of Patent Litigation in Corporate R&D
Authors: Mezzanotti Filippo
Published: February 2021

I examine how patent enforcement affects corporate research and development (R&D), exploiting the legal changes induced by the Supreme Court decision eBay v. MercExchange. This ruling increased courts’ flexibility in remedying patent cases and effectively lowered the potential costs of patent litigation for defendants. For identification, I compare innovative activity across firms differentially exposed to patent litigation before the ruling. Across several measures, I find that the decision led to a general increase in innovation. This result confirms that the changes in enforcement induced by the ruling reduced some of the distortions caused by patent litigation. Exploring the channels, I show that patent litigation negatively affects investment because it lowers the returns from R&D and exacerbates its financing constraints.

This paper was accepted by Gustavo Manso, finance.
Unspanned Global Macro Risks in Bond Returns
Authors: Zhao Feng , Zhou Guofu , Zhu Xiaoneng
Published: February 2021

We examine the macro-spanning hypothesis for bond returns in international markets. Based on a large panel of real-time macroeconomic variables that are not subject to revisions, we find that global macro factors have predictive power for bond returns unspanned by yield factors. Furthermore, we estimate macro-finance term structure models with the unspanned global macro factors and find that the global macro factors influence the market prices of level and slope risks and induce comovements in forward term premia in global bond markets.

This paper was accepted by David Simchi-Levi, finance.
The rise of non-traditional pregnancies through assisted reproductive technologies
Authors: Kaur Amarpreet
Published: February 2021

This article explores how the development of assisted reproductive technologies (ARTs), arisen from in vitro fertilisation, have perpetuated an increase in non-traditional pregnancies ( Franklin, 1997 ). This article discusses what this increase means for midwifery practices and what care midwives may need to consider for such pregnancies. The discussions in this article are based on triangulated findings from a three-phase research design. The research consisted of an online mixed-methods survey of 521 citizens of the UK, semi-structured interviews with experts and professionals who speak to the future of ARTs, and structured interviews with people who are affected by genetic conditions. Findings reveal that applications of ARTs are anticipated to continue to expand with the potential introduction of genome editing technologies to reproductive choices for the prevention of disease. Thus, this article concludes that because of this expansion, the rise of non-traditional pregnancies is likely to continue, and that midwives may benefit from considering the implications the rise could have for midwifery care.
Should the SARS-CoV-2 vaccine be mandatory for nurses? An ethical debate
Authors: Osbourne Rebecca M , Clark Samuel J
Published: February 2021

The COVID-19 pandemic has had a devastating impact on the UK, as well as many other countries around the world, affecting all aspects of society. Nurses and other health and care professionals are a group particularly exposed to the virus through their work. Evidence suggests that vaccines form the most promising strategy for fighting this pandemic. Should vaccination against be mandatory for nurses and other health professionals? This article explores this question using an ethical framework.
Evaluation of processes, outcomes, and use of midline peripheral catheters for the purpose of blood collection
Authors: Penoyer Daleen , Bennett Melody , Geddie Patricia I. , Nugent Alyssa , Volkerson Tara
Published: February 2021

HIGHLIGHTS

Results added knowledge on use of midline catheters (MCs) for blood sampling. Using MCs for blood withdrawal resulted in low rates of hemolysis (0.69%). Dwell time was longer in those who had blood drawn from their MC. Nurse practices for blood sampling from MCs varied and learned from other nurses.

Background:

Blood withdrawal from midline catheters (MCs) is done clinically, but no studies were found evaluating outcomes from this procedure, nor were clinical guidelines found. Drawing blood samples from short peripheral catheters is associated with higher hemolysis rates.

Methods:

A prospective, observational, mixed methods study was used to evaluate outcomes from using MCs for blood withdrawal. Focus group sessions were held to evaluate nurses' practices for this procedure.

Results:

Data were collected over 3 months on 397 MCs in 378 patients. Hemolysis rates when the MC was used for blood withdrawal was 0.69% in 1021 tests. More than half had blood specimens drawn through the MC, and the time known for the successful withdrawal was on average 64 ± 85 hours. Mean dwell time for all MCs was 108.5 ± 98 hours, and when MCs were used for blood withdrawal, mean dwell time was 127.19 ± 109.13 hours and for MCs not used for blood withdrawal, 88.34 ± 79.86 hours (P < 0.001). In 338 patients who received therapy through their MC (n = 338), 87% completed intended therapy: 88% with blood withdrawal and 81% without blood withdrawal. Qualitative analysis from focus groups demonstrated wide variation in practice for blood sampling from MCs, and most learned techniques from their preceptors, other nurses, or patients.

Conclusions:

Findings indicated that blood withdrawal from one specific type of MC had low rates of hemolysis, increased dwell time, and completion of therapy. More studies are needed to determine best practices for blood sampling through various types of MCs and outcomes.
Vertebral fractures and luxations in dogs and cats, part 1: evaluation of diagnosis and prognosis
Authors: Orgonikova Ivona , Brocal Josep , Cherubini Giunio Bruto , Palus Viktor
Published: February 2021

External traumatic injuries such as those caused by road traffic accidents, fights or falls in dogs and cats, can result in vertebral column fracture or luxation. The key to successfully managing such cases is an efficient and accurate initial assessment, followed by stabilisation and immobilisation, to ensure adequate spinal cord blood flow and oxygenation. The crucial prognostic factor for vertebral column fractures or luxations is the presence or absence of nociception. Definitive diagnosis relies on computed tomography since changes, such as fractures of the articular processes, may be missed on radiography. The most appropriate diagnostic method for assessing the severity of the spinal cord injury is magnetic resonance imaging.
Rehabilitating the canine elbow: a practical guide
Authors: Corral Cheryl
Published: February 2021

This article is part of a series exploring the rehabilitation of the individual joints and back of the canine, following injury, surgery, or for management of long-term conditions. Here the different stages in the rehabilitation of the canine elbow are discussed, including several examples of exercises and therapeutic techniques that could be used at each stage of the patient's return to function.
Research Roundup
Authors: Winter George
Published: February 2021

George Winter provides an overview of recently published articles that are of interest to practice nurses. Should you wish to look at any of the papers in more detail, a full reference is provided.
Grafos de Escenas y Estudios Literarios Digitales: Una Propuesta Computacional Crítica
Authors: Jiménez Fernández Concepción María , Calvo Tello José
Published: February 2021

Desde que en 2005 Moretti los popularizase, los grafos se han utilizado para representar la interacción de los personajes en obras de teatro y novelas. Sin embargo, en los últimos años han aparecido algunos trabajos evaluando estos grafos, cuestionando su validez. En este trabajo, proponemos una modificación  de estos grafos, obteniendo una representación de las obras dramáticas que prioriza la estructura en escenas. A diferencia de otros trabajos de HD, realizamos una evaluación crítica mediante hipótesis que aúna variables cuantitativas y cualitativas.
Terahertz pulses induce segment renewal via cell proliferation and differentiation overriding the endogenous regeneration program of the earthworm Eisenia andrei
Authors: Abufadda Mahmoud H. , Erdélyi Anita , Pollák Edit , Nugraha Priyo S. , Hebling János , Fülöp József A. , Molnár László
Published: February 2021

Terahertz (THz) irradiation of excised Eisenia andrei earthworms is shown to cause overriding of the genetically determined, endogenously mediated segment renewing capacity of the model animal. Single-cycle THz pulses of 5 µJ energy, 0.30 THz mean frequency, 293 kV/cm peak electric field, and 1 kHz repetition rate stimulated the cell proliferation (indicated by the high number of mitotic cells) and both histogenesis and organogenesis, producing a significantly higher number of regenerated segments. The most conspicuous alteration in THz-treated animals was the more intense development of the new central nervous system and blood vessels. These results clearly demonstrate that THz pulses are capable to efficiently trigger biological processes and suggest potential applications in medicine.
Neutral point detection using the AOP of polarized skylight patterns
Authors: Fan Zhiguo , Wang Xianqiu , Jin Haihong , Wang Cheng , Pan Ni , Hua Dou
Published: February 2021

The neutral points are one of the most significant characteristics of the polarized skylight pattern in the whole sky. At present, detection of the neutral points mostly utilizes ellipse fitting of the degree of polarization. However, because the degree of polarization distribution characteristics of a polarized skylight pattern is easily affected by the environment, the robustness of the detection is unstable. Aiming at the problem, we analyzed the angle of polarization distribution characteristics of polarized skylight patterns in the region around the neutral point by measurement experiments. Based on this, we proposed an automatic detection method of neutral points using the angle of polarization of the polarized skylight pattern. The experimental results of different times in a continuous period of time show that compared with ellipse fitting of the degree of polarization, the detection accuracy of the proposed method is almost the same, but the robustness is better. It provides a novel method for the position detecting of the neutral point, which is in favor of the measurement applications of polarization technology.
Localized state effect and exciton dynamics for monolayer WS2
Authors: Xu Xuejun , Li Lihui , Yang Mingming , Guo Qinglin , Wang Ying , Li Xiaoli , Zhuang Xiujuan , Liang Baolai
Published: February 2021

The two-dimensional transition metal dichalcogenides (TMDCs) have been considered as promising candidates for developing a new generation of optoelectronic devices. Accordingly, investigations of exciton dynamics are of great importance for understanding the physics and the performance of devices based on TMDCs. Herein, after exposure to ambient environment for six months, monolayer tungsten disulfide (WS2) shows formation of localized states. Photoluminescence (PL) and time-resolved PL (TRPL) spectra demonstrate that these localized states have significant impacts on the exciton dynamics, including energy states filling, thermal activation and redistribution, and the decay behavior of excitons. These observations not only enrich the understanding for localized states and correlated exciton dynamics of aged monolayer WS2, but also reveal a possible approach to modulate the optical properties of TMDCs via the aging process.
Tunable Raman lasing in an As2S3 chalcogenide glass microsphere
Authors: Andrianov Alexey V. , Anashkina Elena A.
Published: February 2021

We demonstrate experimentally Raman lasing in an As2S3 chalcogenide glass microsphere pumped by a C-band narrow line laser. Single-mode Raman lasing tunable from 1.610 μm to 1.663 μm is attained when tuning a pump laser wavelength in the 1.522-1.574 μm range. When the pump power significantly exceeds the threshold, multimode cascade Raman lasing is achieved with the maximum Raman order of four at a wavelength of 2.01 μm. We also report an up-converted wave generation at 1.38 μm which is interpreted as the result of four-wave mixing between the pump wave and the wave generated in the second Raman order. The numerical results based on the simulation of the Lugiato-Lefever equation agree with the experimental results.
Ultrabroadband metamaterial absorbers from ultraviolet to near-infrared based on multiple resonances for harvesting solar energy
Authors: Feng He , Li Xiaoman , Wang Mei , Xia Feng , Zhang Kun , Kong Weijin , Dong Lifeng , Yun Maojin
Published: February 2021

In this paper, a metal-dielectric metamaterial absorber is proposed to achieve ultrabroadband absorption at frequencies from ultraviolet to near-infrared. Based on finite element method solutions, the average absorption of the absorber is 97.75% from 382 nm to 1100 nm, with a maximum of 99.92%, resulting from multiple resonance coupling. The influences of geometric parameters and incident conditions on absorption are investigated. Broadband and narrowband absorption changes are realized by changing incident light polarization. Polarization-independent properties can be realized by changing the dielectric structure to centrosymmetric. The average absorption of the polarization-independent structure is 97.11% from 250 nm to 1115 nm, with a maximum of 99.98%. The proposed absorber structure has wide optical applications including solar energy harvesting and light-emitting devices.
Flexible NOMA-based NOHO-OFDM scheme for visible light communication with iterative interference cancellation
Authors: Huang Xuan , Yang Fang , Pan Changyong , Song Jian
Published: February 2021

In this paper, a flexible non-orthogonal multiple access (NOMA) based optical orthogonal frequency division multiplexing (OFDM) modulation scheme, called non-orthogonal hybrid optical OFDM (NOHO-OFDM), is proposed to increase the achievable data rate of the visible light communication system with high efficiency. In addition, a receiver with iteratively successive interference cancellation (ISIC) is investigated, which can reduce the estimation error. Then, the achievable data rate of the proposed NOHO-OFDM with the ISIC scheme is analyzed. Experiment results show that the bit error rate of the NOHO-OFDM can be significantly reduced by the proposed ISIC scheme, and the NOHO-OFDM is superior than the orthogonal scheme in terms of data rates. Meanwhile, simulation results show that the achievable data rate region of the proposed NOHO-OFDM scheme is larger than that of the orthogonal counterpart.
Adaptive dating and fast proposals: Revisiting the phylogenetic relaxed clock model
Authors: Douglas Jordan , Zhang Rong , Bouckaert Remco
Published: February 2021

Relaxed clock models enable estimation of molecular substitution rates across lineages and are widely used in phylogenetics for dating evolutionary divergence times. Under the (uncorrelated) relaxed clock model, tree branches are associated with molecular substitution rates which are independently and identically distributed. In this article we delved into the internal complexities of the relaxed clock model in order to develop efficient MCMC operators for Bayesian phylogenetic inference. We compared three substitution rate parameterisations, introduced an adaptive operator which learns the weights of other operators during MCMC, and we explored how relaxed clock model estimation can benefit from two cutting-edge proposal kernels: the AVMVN and Bactrian kernels. This work has produced an operator scheme that is up to 65 times more efficient at exploring continuous relaxed clock parameters compared with previous setups, depending on the dataset. Finally, we explored variants of the standard narrow exchange operator which are specifically designed for the relaxed clock model. In the most extreme case, this new operator traversed tree space 40% more efficiently than narrow exchange. The methodologies introduced are adaptive and highly effective on short as well as long alignments. The results are available via the open source optimised relaxed clock (ORC) package for BEAST 2 under a GNU licence (https://github.com/jordandouglas/ORC).
Steroid hormone ecdysone deficiency stimulates preparation for photoperiodic reproductive diapause
Authors: Guo Shuang , Tian Zhong , Wu Qing-Wen , King-Jones Kirst , Liu Wen , Zhu Fen , Wang Xiao-Ping
Published: February 2021

Diapause, a programmed developmental arrest primarily induced by seasonal environmental changes, is very common in the animal kingdom, and found in vertebrates and invertebrates alike. Diapause provides an adaptive advantage to animals, as it increases the odds of surviving adverse conditions. In insects, individuals perceive photoperiodic cues and modify endocrine signaling to direct reproductive diapause traits, such as ovary arrest and increased fat accumulation. However, it remains unclear as to which endocrine factors are involved in this process and how they regulate the onset of reproductive diapause. Here, we found that the long day-mediated drop in the concentration of the steroid hormone ecdysone is essential for the preparation of photoperiodic reproductive diapause in Colaphellus bowringi, an economically important cabbage beetle. The diapause-inducing long-day condition reduced the expression of ecdysone biosynthetic genes, explaining the drop in the titer of 20-hydroxyecdysone (20E, the active form of ecdysone) in female adults. Application of exogenous 20E induced vitellogenesis and ovarian development but reduced fat accumulation in the diapause-destined females. Knocking down the ecdysone receptor (EcR) in females destined for reproduction blocked reproductive development and induced diapause traits. RNA-seq and hormone measurements indicated that 20E stimulates the production of juvenile hormone (JH), a key endocrine factor in reproductive diapause. To verify this, we depleted three ecdysone biosynthetic enzymes via RNAi, which confirmed that 20E is critical for JH biosynthesis and reproductive diapause. Importantly, impairing Met function, a component of the JH intracellular receptor, partially blocked the 20E-regulated reproductive diapause preparation, indicating that 20E regulates reproductive diapause in both JH-dependent and -independent manners. Finally, we found that 20E deficiency decreased ecdysis-triggering hormone signaling and reduced JH production, thereby inducing diapause. Together, these results suggest that 20E signaling is a pivotal regulator that coordinates reproductive plasticity in response to environmental inputs.
Tsetse salivary glycoproteins are modified with paucimannosidic N-glycans, are recognised by C-type lectins and bind to trypanosomes
Authors: Kozak Radoslaw P. , Mondragon-Shem Karina , Williams Christopher , Rose Clair , Perally Samirah , Caljon Guy , Van Den Abbeele Jan , Wongtrakul-Kish Katherine , Gardner Richard A. , Spencer Daniel , Lehane Michael J. , Acosta-Serrano Álvaro
Published: February 2021

African sleeping sickness is caused by Trypanosoma brucei, a parasite transmitted by the bite of a tsetse fly. Trypanosome infection induces a severe transcriptional downregulation of tsetse genes encoding for salivary proteins, which reduces its anti-hemostatic and anti-clotting properties. To better understand trypanosome transmission and the possible role of glycans in insect bloodfeeding, we characterized the N-glycome of tsetse saliva glycoproteins. Tsetse salivary N-glycans were enzymatically released, tagged with either 2-aminobenzamide (2-AB) or procainamide, and analyzed by HILIC-UHPLC-FLR coupled online with positive-ion ESI-LC-MS/MS. We found that the N-glycan profiles of T. brucei-infected and naïve tsetse salivary glycoproteins are almost identical, consisting mainly (>50%) of highly processed Man3GlcNAc2 in addition to several other paucimannose, high mannose, and few hybrid-type N-glycans. In overlay assays, these sugars were differentially recognized by the mannose receptor and DC-SIGN C-type lectins. We also show that salivary glycoproteins bind strongly to the surface of transmissible metacyclic trypanosomes. We suggest that although the repertoire of tsetse salivary N-glycans does not change during a trypanosome infection, the interactions with mannosylated glycoproteins may influence parasite transmission into the vertebrate host.
Development of photosynthetic carbon fixation model using multi-excitation wavelength fast repetition rate fluorometry in Lake Biwa
Authors: Kazama Takehiro , Hayakawa Kazuhide , Kuwahara Victor S. , Shimotori Koichi , Imai Akio , Komatsu Kazuhiro
Published: February 2021

Direct measurements of gross primary productivity (GPP) in the water column are essential, but can be spatially and temporally restrictive. Fast repetition rate fluorometry (FRRf) is a bio-optical technique based on chlorophyll a (Chl-a) fluorescence that can estimate the electron transport rate (ETRPSII) at photosystem II (PSII) of phytoplankton in real time. However, the derivation of phytoplankton GPP in carbon units from ETRPSII remains challenging because the electron requirement for carbon fixation (Фe,C), which is mechanistically 4 mol e− mol C−1 or above, can vary depending on multiple factors. In addition, FRRf studies are limited in freshwater lakes where phosphorus limitation and cyanobacterial blooms are common. The goal of the present study is to construct a robust Фe,C model for freshwater ecosystems using simultaneous measurements of ETRPSII by FRRf with multi-excitation wavelengths coupled with a traditional carbon fixation rate by the 13C method. The study was conducted in oligotrophic and mesotrophic parts of Lake Biwa from July 2018 to May 2019. The combination of excitation light at 444, 512 and 633 nm correctly estimated ETRPSII of cyanobacteria. The apparent range of Фe,C in the phytoplankton community was 1.1–31.0 mol e− mol C−1 during the study period. A generalised linear model showed that the best fit including 12 physicochemical and biological factors explained 67% of the variance in Фe,C. Among all factors, water temperature was the most significant, while photosynthetically active radiation intensity was not. This study quantifies the in situ FRRf method in a freshwater ecosystem, discusses core issues in the methodology to calculate Фe,C, and assesses the applicability of the method for lake GPP prediction.
Fibroblast Growth Factor 9 (FGF9) negatively regulates the early stage of chondrogenic differentiation
Authors: Zhang Xiaoyue , Weng Mengjia , Chen Zhenqi
Published: February 2021

Fibroblast growth factor signaling is essential for mammalian bone morphogenesis and growth, involving membranous ossification and endochondral ossification. FGF9 has been shown to be an important regulator of endochondral ossification; however, its role in the early differentiation of chondrocytes remains unknown. Therefore, in this study, we aimed to determine the role of FGF9 in the early differentiation of chondrogenesis. We found an increase in FGF9 expression during proliferating chondrocyte hypertrophy in the mouse growth plate. Silencing of FGF9 promotes the growth of ATDC5 cells and promotes insulin-induced differentiation of ATDC5 chondrocytes, which is due to increased cartilage matrix formation and type II collagen (col2a1) and X (col10a1), Acan, Ihh, Mmp13 gene expression. Then, we evaluated the effects of AKT, GSK-3β, and mTOR. Inhibition of FGF9 significantly inhibits phosphorylation of AKT and GSK-3β, but does not affected the activation of mTOR. Furthermore, phosphorylation of inhibited AKT and GSK-3β was compensated using the AKT activator SC79, and differentiation of ATDC5 cells was inhibited. In conclusion, our results indicate that FGF9 acts as an important regulator of early chondrogenesis partly through the AKT/GSK-3β pathway.
The role of aquaporin-4 in optic nerve head astrocytes in experimental glaucoma
Authors: Kimball Elizabeth , Schaub Julie , Quillen Sarah , Keuthan Casey , Pease Mary Ellen , Korneva Arina , Quigley Harry
Published: February 2021

Purpose

To study aquaporin channel expression in astrocytes of the mouse optic nerve (ON) and the response to IOP elevation in mice lacking aquaporin 4 (AQP4 null).

Methods

C57BL/6 (B6) and AQP4 null mice were exposed to bead-induced IOP elevation for 3 days (3D-IOP), 1 and 6 weeks. Mouse ocular tissue sections were immunolabeled against aquaporins 1(AQP1), 4(AQP4), and 9(AQP9). Ocular tissue was imaged to identify normal AQP distribution, ON changes, and axon loss after IOP elevation. Ultrastructure examination, cell proliferation, gene expression, and transport block were also analyzed.

Results

B6 mice had abundant AQP4 expression in Müller cells, astrocytes of retina and myelinated ON (MON), but minimal AQP4in prelaminar and unmyelinated ON (UON). MON of AQP4 nulls had smaller ON area, smaller axon diameter, higher axon density, and larger proportionate axon area than B6 (all p≤0.05). Bead-injection led to comparable 3D-IOP elevation (p = 0.42) and axonal transport blockade in both strains. In B6, AQP4 distribution was unchanged after 3D-IOP. At baseline, AQP1 and AQP9 were present in retina, but not in UON and this was unaffected after IOP elevation in both strains. In 3D-IOP mice, ON astrocytes and microglia proliferated, more in B6 than AQP4 null. After 6 week IOP elevation, axon loss occurred equally in the two mouse types (24.6%, AQP4 null vs. 23.3%, B6).

Conclusion

Lack of AQP4 was neither protective nor detrimental to the effects of IOP elevation. The minimal presence of AQP4 in UON may be a vital aspect of the regionally specific phenotype of astrocytes in the mouse optic nerve head.
Anemia in tuberculosis cases: A biomarker of severity?
Authors: de Mendonça Edson Beyker , Schmaltz Carolina AranaStanis , Sant’Anna Flavia Marinho , Vizzoni Alexandre Gomes , Mendes-de-Almeida Daniela Palheiro , de Oliveira Raquel de Vasconcellos Carvalhaes , Rolla Valeria Cavalcanti
Published: February 2021

Introduction

Anemia is a common condition at tuberculosis diagnosis, and there is evidence that its prevalence is higher in patients with tuberculosis than in those infected with Mycobacterium tuberculosis and healthy controls. Information about anemia during tuberculosis diagnosis is still scarce in the Brazilian population. The aim of this study was to describe the prevalence of anemia in patients with tuberculosis cared for at a referral center and its association with clinical forms of tuberculosis and other characteristics of these patients.

Materials and methods

This was a retrospective cross-sectional study of tuberculosis patients diagnosed from January 2015 to December 2018 at the Clinical Research Laboratory on Mycobacteria (LAPCLIN-TB) of Evandro Chagas National Institute of Infectious Diseases (INI)/Oswaldo Cruz Foundation (Fiocruz). A database of an ongoing cohort study underway at this service since 2000 provided the baseline information on tuberculosis cases extracted from a visit template. Exploratory and logistic regression analyses were performed to verify associations between anemia and demographic characteristics, socioeconomic status, clinical conditions, and laboratory results.

Results

Of the 328 cases reviewed, 70 were excluded, with258 retained. The prevalence of anemia was 61.2% (27.5% mild, 27.5% moderate and 6.2% severe). Among patients with anemia, 60.8% had normochromic normocytic anemia, and 27.8% showed hypochromic microcytic anemia. In logistic regression analysis, anemia was associated with a history of weight loss >10%, hospitalizations, coinfection with HIV, increased platelet count and microcytosis. Anemia was more frequent in the most severe clinical forms, such as meningeal and disseminated tuberculosis.

Conclusions

Anemia was highly prevalent in tuberculosis patients at diagnosis, predominantly as normochromic normocytic anemia and in mild and moderate forms. It was associated with baseline characteristics and conditions indicative of severe disease, suggesting that anemia could be a biomarker of tuberculosis severity.
Testing the effect of pollen exine rupture on metabarcoding with Illumina sequencing
Authors: Swenson Stephanie J. , Gemeinholzer Birgit
Published: February 2021

Pollen metabarcoding has received much attention recently for its potential to increase taxonomic resolution of the identifications of pollen grains necessary for various public health, ecological and environmental inquiry. However, methodologies implemented are widely varied across studies confounding comparisons and casting uncertainty on the reliability of results. In this study, we investigated part of the methodology, the effects of level of exine rupture and lysis incubation time, on the performance of DNA extraction and Illumina sequencing. We examined 15 species of plants from 12 families with pollen that varies in size, shape, and aperture number to evaluate effort necessary for exine rupture. Then created mock communities of 14 of the species from DNA extractions at 4 levels of exine rupture (0, 33, 67, and 100%) and two levels of increased lysis incubation time without exine rupture (2 or 24 hours). Quantities of these DNA extractions displayed a positive correlation between increased rupture and DNA yield, however increasing time of lysis incubation was associated with decreased DNA yield. Illumina sequencing was performed with these artificial community treatments with three common plant DNA barcode regions (rbcL, ITS1, ITS2) with two different primer pairings for ITS2 andrbcL. We found decreased performance in treatments with 0% or 100% exine rupture compared to 33% and 67% rupture, based on deviation from expected proportions and species retrieval, and increased lysis incubation was found to be detrimental to results.