bluuebunny/crossref_metadata_2025 huggingface dataset:
All-polymer whispering gallery mode resonators for gas sensing
Authors: Lemieux-Leduc Cédric , Guertin Régis , Bianki Marc-Antoine , Peter Yves-Alain
Published: February 2021

Sensitivity of polymeric microdisks is evaluated for selected compounds in their vapor phase such as humidity, isopropanol, toluene, limonene, 1-butanol, and pentanoic acid (valeric acid). Among these compounds, pentanoic acid exhibits the highest sensitivity (23 pm/ppm) with a limit of detection estimated to be around 0.6 ppm. We are interested in the contribution of the geometry deformation due to polymer swelling on the sensitivity as it may be engineered to improve performance of gas sensing devices. Experimental observations show a trend where sensitivity to humidity increased with the ratio of the undercut over the radius of the microcavity.
Nonlinear signal errors in homodyne laser Doppler vibrometry induced by strong second-order ghost reflections and their mitigation
Authors: Li Yanlu , Baets Roel
Published: February 2021

A variety of mechanisms can induce distortions in the output signals of a homodyne laser Doppler vibrometer (LDV). In this paper, the nonlinear LDV distortions caused by a strong second-order ghost reflection originating from lens flares are theoretically explained and analyzed. We propose a simple compensation method to mitigate this distortion. The performance and limitations of this method are also explained both in simulation and in experiment.
Transmission and imaging characteristics of flexible gradually tapered waveguide at 0.3 THz
Authors: He Menghui , Zeng Jiafu , Zhang Xian , Zhu Xiaosong , Jing Chengbin , Chang Chao , Shi Yiwei
Published: February 2021

Flexible gradually tapered metal waveguides (GTMWs) are fabricated by an inner plating silver film in a polycarbonate (PC) capillary for the transmission and imaging at 0.3 THz. It was demonstrated theoretically and experimentally that GTMWs have lower transmission losses and smaller additional losses of bending, comparing with thin constant bore metal waveguides (CBMWs). Measured losses of 1.95 dB and 2.45 dB were obtained for a 1 m long GTMW with bore size varying from 2.6 mm to 1.6 mm under straight and one circle bending configuration. Measured losses were 4.48 dB/m and 7.78 dB/m for 1.6 mm bore CBMW under the same straight and bend configurations. Owing to higher energy concentration at the output, a larger penetration ability of output wave can be achieved by GTMW, which is beneficial for imaging application. A scanning imaging system was established using fabricated waveguides as the probes. Measured results show that the air slits of the order of wavelength can be clearly distinguished. An imaging system with a GTMW probe also has better performances due to lower bending loss and improved coupling efficiency.
Full-color retinal-projection near-eye display using a multiplexing-encoding holographic method
Authors: Song Weitao , Li Xin , Zheng Yuanjin , Liu Yue , Wang Yongtian
Published: February 2021

We propose a novel method to construct an optical see-through retinal-projection near-eye display using the Maxwellian view and a holographic method. To provide a dynamic full-color virtual image, a single phase-only spatial light modulator (SLM) was employed in conjunction with a multiplexing-encoding holographic method. Holographic virtual images can be directly projected onto the retina using an optical see-through eyepiece. The virtual image is sufficiently clear when the crystal lens can focus at different depths; the presented method can resolve convergence and accommodation conflict during the use of near-eye displays. To verify the proposed method, a proof-of-concept prototype was developed to provide vivid virtual images alongside real-world ones.
Quantitative spectroscopy of single molecule interaction times
Authors: Boltz H.-H. , Sirbu A. , Stelzer N. , Lohse M. J. , Schütte C. , Annibale P.
Published: February 2021

Single molecule fluorescence tracking provides information at nanometer-scale and millisecond-temporal resolution about the dynamics and interaction of individual molecules in a biological environment. While the dynamic behavior of isolated molecules can be characterized well, the quantitative insight is more limited when interactions between two indistinguishable molecules occur. We address this aspect by developing a theoretical foundation for a spectroscopy of interaction times, i.e., the inference of interaction from imaging data. A non-trivial crossover between a power law to an exponential behavior of the distribution of the interaction times is highlighted, together with the dependence of the exponential term upon the microscopic reaction affinity. Our approach is validated with simulated and experimental datasets.
Broadband and fine-structured luminescence in diamond facilitated by femtosecond laser driven electron impact and injection of “vacancy-interstitial” pairs
Authors: Kudryashov S. I. , Khmelnitskii R. A. , Danilov P. A. , Smirnov N. A. , Levchenko A. O. , Kovalchuk O. E. , Uspenskaya M. V. , Oleynichuk E. A. , Kovalev M. S.
Published: February 2021

Ultrafast heating of photoionized free electrons by high-numerical-aperture (0.25–0.65) focused visible-range ultrashort laser pulses provides their resonant impact trapping into intra-gap electronic states of point defect centers in a natural IaA/B diamond with a high concentration of poorly aggregated nitrogen impurity atoms. This excites fine-structured, broadband (UV-near-infrared) polychromatic luminescence of the centers over the entire bandgap. The observed luminescence spectra revealed substitutional nitrogen interaction with non-equilibrium intrinsic carbon vacancies, produced simultaneously as Frenkel “vacancy-interstitial” pairs during the laser exposure.
Gradient-assisted focusing light through scattering media
Authors: Zhao Yanyu , He Qiaozhi , Li Shuna , Yang Jiamiao
Published: February 2021

Focusing light through a scattering medium is a longstanding challenge
in biomedical optics, to which wavefront shaping is a powerful
solution. The state-of-the-art feedback-based approach is the widely
used genetic algorithm method. However, it can only achieve relatively
low enhancement of the focus, and the genetic algorithm is known to be
time-consuming. To tackle those issues, we propose a gradient-assisted
strategy for wavefront shaping. The proposed method conducts
optimization in the function distribution space. Specifically, when
optimizing the parameters along each iteration, the consequent
function distribution changes within a distance as measured by the
Kullback–Leibler divergence. Taking advantage of the gradient
information, the proposed method is over

60

×

faster to obtain the same
peak-to-background ratio (PBR) level. Compared with the genetic
algorithm that is able to optimize a number of

64

×
64

phase segments, the proposed gradient
strategy is able to optimize

256

×
256

phase segments, and gives

20

×

higher focus enhancement as
quantified by the PBR.
5  kW monolithic fiber amplifier employing homemade spindle-shaped ytterbium-doped fiber
Authors: Zeng Lingfa , Pan Zhiyong , Xi Xiaoming , Yang Huan , Ye Yun , Huang Liangjin , Zhang Hanwei , Wang Xiaolin , Wang Zefeng , Zhou Pu , Xu Xiaojun , Chen Jinbao
Published: February 2021

We have demonstrated a 5 kW high-power monolithic fiber amplifier employing a homemade spindle-shaped ytterbium-doped fiber (YDF) based on the main oscillator power amplifier configuration. The YDF consists of a spindle-shaped core and cladding along the fiber length, with a core/cladding diameter of 27/410 µm at both ends and 39.5/600 µm in the middle. An output power of over 5 kW and beam quality of about 1.9 and an optical-to-optical conversion efficiency of 66.6% were achieved in the amplifier under a bidirectional pump scheme. While operating at the maximum power, the laser performance was evaluated, and the transverse mode instability and stimulated Raman scattering effects were well mitigated. To the best of our knowledge, this is the highest power demonstration in a continuous-wave fiber laser employing a tapered fiber. Further power scaling is promising by optimizing the structure of the YDF.
Silicon photonic on-chip spatial heterodyne Fourier transform spectrometer exploiting the Jacquinot’s advantage
Authors: Dinh Thi Thuy Duong , González-Andrade David , Montesinos-Ballester Miguel , Deniel Lucas , Szelag Bertrand , Le Roux Xavier , Cassan Eric , Marris-Morini Delphine , Vivien Laurent , Cheben Pavel , Velasco Aitor V. , Alonso-Ramos Carlos
Published: February 2021

Silicon photonics on-chip spectrometers are finding important applications in medical diagnostics, pollution monitoring, and astrophysics. Spatial heterodyne Fourier transform spectrometers (SHFTSs) provide a particularly interesting architecture with a powerful passive error correction capability and high spectral resolution. Despite having an intrinsically large optical throughput (étendue, also referred to as Jacquinot’s advantage), state-of-the-art silicon SHFTSs have not exploited this advantage yet. Here, we propose and experimentally demonstrate for the first time, to the best of our knowledge, an SHFTS implementing a wide-area light collection system simultaneously feeding an array of 16 interferometers, with an input aperture as large as

90

µ

m

×

60

µ

m

formed by a two-way-fed grating coupler. We experimentally demonstrate 85 pm spectral resolution, 600 pm bandwidth, and 13 dB étendue increase, compared with a device with a conventional grating coupler input. The SHFTS was fabricated using 193 nm deep-UV optical lithography and integrates a large-size input aperture with an interferometer array and monolithic Ge photodetectors, in a

4.5

m
m

2

footprint.
Non-diffracting and self-accelerating Bessel beams with on-demand tailored intensity profiles along arbitrary trajectories
Authors: Yan Wenxiang , Gao Yuan , Yuan Zheng , Wang Zhuang , Ren Zhi-Cheng , Wang Xi-Lin , Ding Jianping , Wang Hui-Tian
Published: February 2021

Owing to their robustness against diffraction, Bessel beams (BBs) offer special advantages in various applications. To enhance their applicability, we present a method to generate self-accelerating zeroth-order BBs along predefined trajectories with tunable

z

direction intensity profiles. The character of tunable

z

direction intensity profiles in non-diffracting self-accelerating BBs potentially can attract interest in the regimes of particle manipulation, microfabrication, and free-space optical interconnects.
Label-free plasmonic assisted optical trapping of single DNA molecules
Authors: Chen Lei , Liu Wei , Shen Dongyi , Zhou Zhihao , Liu Yuehan , Wan Wenjie
Published: February 2021

DNA molecules are hard to catch using traditional optical trapping due to the nanometer width of their chains. Here we experimentally demonstrate a label-free optical trapping of a single micrometer

λ

-DNA in solution by the aid of plasmonic gold nanoparticles (GNPs), where a double-laser trap induces strong optical interparticle forces for the tweezer. We examine such sub-resolved interparticle forces by tracking the GNP dynamics in solution. Moreover, surface-enhanced Raman scattering signals of trapped

λ

-DNA have also been measured simultaneously in the same setup. In comparison with prior works, ours benefit from the excitation in a dynamic configuration without fabrication. This technique opens a new avenue for all-optical manipulation of biomolecules, as well as ultra-sensitive bio-medical sensing applications.
Use of machine learning to efficiently predict the confinement loss in anti-resonant hollow-core fiber
Authors: Meng Fanchao , Zhao Xiaoting , Ding Jinmin , Niu Yingli , Zhang Xinghua , Smietana Mateusz , Buczyński Ryszard , Lin Bo , Tao Guangming , Yang Lvyun , Wang Xin , Lou Shuqin , Sheng Xinzhi , Liang Sheng
Published: February 2021

The fundamental mode confinement loss (CL) of anti-resonant hollow-core fiber (ARF) is efficiently predicted by a classification task of machine learning. The structure–parameter vector is utilized to define the sample space of ARFs. The CL of labeled samples at 1550 nm is numerically calculated via the finite element method (FEM). The magnitude of CL is obtained by a classification task via a decision tree and

k

-nearest neighbors algorithms with the training and test sets generated by 290700 and 32300 labeled samples. The test accuracy, confusion matrices, and the receiver operating characteristic curves have shown that our proposed method is effective for predicting the magnitude of CL with a short computation runtime compared to FEM simulation. The feasibility of predicting other performance parameters by the extension of our method, as well as its ability to generalize outside the tested sample space, is also discussed. It is likely that the proposed sample definition and the use of a classification approach can be adopted for design application beyond efficient prediction of ARF CL and inspire artificial intelligence and data-driven-based research of photonic structures.
Al2O3 anti-reflection coatings with graded-refractive index profile for laser applications
Authors: Yin Chaoyi , Zhu Meiping , Zeng Tingting , Sun Jian , Zhang Rongjun , Zhao Jiaoling , Wang Longsheng , Shao Jianda
Published: February 2021

Al2O3 coating is chemically unstable in hot water and transforms into a porous structure with a broadband anti-reflection (AR) property. We investigate the influences of treatment time on the AR property and structure morphology of the Al2O3 coating deposited by electron beam evaporation. Al2O3 coating treated for 7 minutes is found to possess the best AR property with an average reflectance of approximately 0.3% in the wavelength range of 350 nm to 1100 nm. The genetic algorithm simulation shows the treated Al2O3 coating possesses a graded-refractive index profile. The scattering calculation shows a large scattering in the short wavelength range. Moreover, we investigate the laser-resistance of the treated Al2O3 coating, and it shows the potential for application in laser systems.
On-chip optical tweezers based on freeform optics
Authors: Yu Shaoliang , Lu Jinsheng , Ginis Vincent , Kheifets Simon , Lim Soon Wei Daniel , Qiu Min , Gu Tian , Hu Juejun , Capasso Federico
Published: February 2021

Since its advent in the 1970s, optical tweezers have been widely deployed as a preferred non-contact technique for manipulating microscale objects. On-chip integrated optical tweezers, which afford significant size, weight, and cost benefits, have been implemented, relying upon near-field evanescent waves. As a result, these tweezers are only capable of manipulation in near-surface regions and often demand high power since the evanescent interactions are relatively weak. We introduce on-chip optical tweezers based on freeform micro-optics, which comprise optical reflectors or refractive lenses integrated on waveguide end facets via two-photon polymerization. The freeform optical design offers unprecedented degrees of freedom to design optical fields with strong three-dimensional intensity gradients, useful for trapping and manipulating suspended particles in an integrated chip-scale platform. We demonstrate the design, fabrication, and measurement of both reflective and refractive micro-optical tweezers. The reflective tweezers feature a remarkably low trapping threshold power, and the refractive tweezers are particularly useful for multiparticle trapping and interparticle interaction analysis. Our integrated micro-optical tweezers uniquely combine a compact footprint, broadband operation, high trapping efficiency, and scalable integration with planar photonic circuits. This class of tweezers is promising for on-chip sensing, cell assembly, particle dynamics analysis, and ion trapping.
Controllable one-step doping synthesis for the white-light emission of cesium copper iodide perovskites
Authors: Fan Ranran , Fang Shaofan , Liang Chengchuan , Liang Zhaoxing , Zhong Haizhe
Published: February 2021

In this paper, a controllable one-step doping method has been successfully adopted in the cesium copper iodide perovskite’s luminescence, a high-quality white-light emission with Commission Internationale de l´Eclairage (CIE) coordinates of (0.3397, 0.3325), and a color rendering index (CRI) reaching up to 90 was realized in a convenient way. Through adding impurities into the

Cs

3

Cu

2

I

5

system, high efficiency and stable

CsCu

2

I
3

was synthesized, and the coexistence of varied high luminescence phases realized the white lighting. Strikingly, blue-emitting

Cs

3

Cu

2

I
5

and yellow-emitting

CsCu

2

I
3

could coexist, and their respective luminescence was not interacted in the compound, which was beneficial for acquiring a single emission and highly efficient white lighting. This work carried out a deep exploration of the Cu-based metal halides, and would be favorable to the applications of lead-free perovskites.
Spin-selective corner reflector for retro-reflection and absorption by a circular dichroitic manner
Authors: Wang He , Jing Yao , Li Yongfeng , Huang Lingling , Feng Maochang , Yuan Qi , Wang Jiafu , Zhang Jieqiu , Qu Shaobo
Published: February 2021

Recently, we have witnessed an extraordinary spurt in attention toward manipulating electromagnetic waves by metasurfaces. Particularly, tailoring of circular polarization has attracted great amounts of interest in both microwave and optics regimes. Circular dichroism, an exotic chiroptical effect of natural molecules, has aroused discussion about this issue, yet it is still in its infancy. Herein, we initiate circular dichroism followed by controlling spin-selective wavefronts via chiral metasurfaces. An N-shaped chiral resonator loaded with two lumped resistors is proposed as the meta-atom producing an adequate phase gradient. Assisted by the ohmic dissipation of the introduced resistors, the effect of differential absorption provides an auxiliary degree of freedom for developing circularly polarized waves with a designated spin state. A planar corner reflector that can achieve retro-reflection and absorption for right- and left-handed circularly polarized incidence is theoretically simulated and experimentally observed at microwave frequency. Thus, our effort provides an alternative approach to tailoring electromagnetic waves in a circular dichroitic manner and may also find applications in multi-functional systems in optics and microwave regimes.
Spectrally specific temporal analyses of spike-train responses to complex sounds: A unifying framework
Authors: Parida Satyabrata , Bharadwaj Hari , Heinz Michael G.
Published: February 2021

Significant scientific and translational questions remain in auditory neuroscience surrounding the neural correlates of perception. Relating perceptual and neural data collected from humans can be useful; however, human-based neural data are typically limited to evoked far-field responses, which lack anatomical and physiological specificity. Laboratory-controlled preclinical animal models offer the advantage of comparing single-unit and evoked responses from the same animals. This ability provides opportunities to develop invaluable insight into proper interpretations of evoked responses, which benefits both basic-science studies of neural mechanisms and translational applications, e.g., diagnostic development. However, these comparisons have been limited by a disconnect between the types of spectrotemporal analyses used with single-unit spike trains and evoked responses, which results because these response types are fundamentally different (point-process versus continuous-valued signals) even though the responses themselves are related. Here, we describe a unifying framework to study temporal coding of complex sounds that allows spike-train and evoked-response data to be analyzed and compared using the same advanced signal-processing techniques. The framework uses a set of peristimulus-time histograms computed from single-unit spike trains in response to polarity-alternating stimuli to allow advanced spectral analyses of both slow (envelope) and rapid (temporal fine structure) response components. Demonstrated benefits include: (1) novel spectrally specific temporal-coding measures that are less confounded by distortions due to hair-cell transduction, synaptic rectification, and neural stochasticity compared to previous metrics, e.g., the correlogram peak-height, (2) spectrally specific analyses of spike-train modulation coding (magnitude and phase), which can be directly compared to modern perceptually based models of speech intelligibility (e.g., that depend on modulation filter banks), and (3) superior spectral resolution in analyzing the neural representation of nonstationary sounds, such as speech and music. This unifying framework significantly expands the potential of preclinical animal models to advance our understanding of the physiological correlates of perceptual deficits in real-world listening following sensorineural hearing loss.
Computational modeling of the gut microbiota reveals putative metabolic mechanisms of recurrent Clostridioides difficile infection
Authors: Henson Michael A.
Published: February 2021

Approximately 30% of patients who have Clostridioides difficile infection (CDI) will suffer at least one incident of reinfection. While the underlying causes of CDI recurrence are poorly understood, interactions between C. difficile and commensal gut bacteria are thought to play an important role. In this study, an in silico pipeline was used to process 16S rRNA gene amplicon sequence data of 225 stool samples from 93 CDI patients into sample-specific models of bacterial community metabolism. Clustered metabolite production rates generated from post-diagnosis samples generated a high Enterobacteriaceae abundance cluster containing disproportionately large numbers of recurrent samples and patients. This cluster was predicted to have significantly reduced capabilities for secondary bile acid synthesis but elevated capabilities for aromatic amino acid catabolism. When applied to 16S sequence data of 40 samples from fecal microbiota transplantation (FMT) patients suffering from recurrent CDI and their stool donors, the community modeling method generated a high Enterobacteriaceae abundance cluster with a disproportionate large number of pre-FMT samples. This cluster also was predicted to exhibit reduced secondary bile acid synthesis and elevated aromatic amino acid catabolism. Collectively, these in silico predictions suggest that Enterobacteriaceae may create a gut environment favorable for C. difficile spore germination and/or toxin synthesis.
Health beliefs and health seeking behavior towards lymphatic filariasis morbidity management and disability prevention services in Luangwa District, Zambia: Community and provider perspectives
Authors: Maritim Patricia , Silumbwe Adam , Zulu Joseph Mumba , Sichone George , Michelo Charles
Published: February 2021

Background

Morbidity management and disability prevention (MMDP) services are essential for the management of chronic stages of lymphatic filariasis (LF) infection. However, there is limited information on health beliefs and health seeking behavior towards MMDP services for LF in endemic regions of Zambia. This study sought to document health beliefs and health seeking behavior towards MMDP services for LF in Luangwa District, Zambia.

Methods

This was an exploratory qualitative study conducted with community members including LF patients, community health workers and healthcare providers. Data was collected through a series of four focus group discussions stratified by sex and 26 in-depth interviews. Data was analyzed by thematic analysis using NVivo software.

Results

The perceived causes of the chronic manifestations of LF included; contact with animal faeces, use of traditional herbal aphrodisiacs (mutoto), witchcraft and sexual contact with women who were menstruating or had miscarried. LF patients opted to visit traditional healers before going to health facilities. Hydrocele patients were afraid of hydrocelectomies as they were thought to cause infertility or death. Very few community members were able to identify any home and facility-based care strategies for lymphoedema. Health system and cultural barriers to seeking healthcare included; long distances to the health facilities, lack of awareness of existing MMDP services, perceived costs of accessing MMDP services, gender and social norms, and fear of stigmatization.

Conclusion

Health seeking behavior for LF in the district is mainly driven by negative beliefs about the causes of the disease and lack of awareness of available MMDP services and homecare strategies. Lymphatic filariasis programs should promote strategies that seek to empower patients and community members with the required information to access and use the MMDP services at the health facilities, as well as adhere to self-care practices in their households.
Accuracy and precision of citizen scientist animal counts from drone imagery
Authors: Wood Sarah A. , Robinson Patrick W. , Costa Daniel P. , Beltran Roxanne S.
Published: February 2021

Repeated counts of animal abundance can reveal changes in local ecosystem health and inform conservation strategies. Unmanned aircraft systems (UAS), also known as drones, are commonly used to photograph animals in remote locations; however, counting animals in images is a laborious task. Crowd-sourcing can reduce the time required to conduct these censuses considerably, but must first be validated against expert counts to measure sources of error. Our objectives were to assess the accuracy and precision of citizen science counts and make recommendations for future citizen science projects. We uploaded drone imagery from Año Nuevo Island (California, USA) to a curated Zooniverse website that instructed citizen scientists to count seals and sea lions. Across 212 days, over 1,500 volunteers counted animals in 90,000 photographs. We quantified the error associated with several descriptive statistics to extract a single citizen science count per photograph from the 15 repeat counts and then compared the resulting citizen science counts to expert counts. Although proportional error was relatively low (9% for sea lions and 5% for seals during the breeding seasons) and improved with repeat sampling, the 12+ volunteers required to reduce error was prohibitively slow, taking on average 6 weeks to estimate animals from a single drone flight covering 25 acres, despite strong public outreach efforts. The single best algorithm was ‘Median without the lowest two values’, demonstrating that citizen scientists tended to under-estimate the number of animals present. Citizen scientists accurately counted adult seals, but accuracy was lower when sea lions were present during the summer and could be confused for seals. We underscore the importance of validation efforts and careful project design for researchers hoping to combine citizen science with imagery from drones, occupied aircraft, and/or remote cameras.
Revisit incidence of complications after impacted mandibular third molar extraction: A nationwide population-based cohort study
Authors: Chen Ya-Wei , Chi Lin-Yang , Lee Oscar Kuang-Sheng
Published: February 2021

Most of complications after impacted mandibular third molar (iLM3) extraction surgeries are transient and resolved spontaneously within one or two weeks, but some of them are more complicated and required further treatments to alleviate the symptoms. The aim of study is to revisit incidence and predictors of complications after iLM3 surgery by reviewing previous literature and investigating a population-based data. From Taiwan National Health Insurance Research Database, records of 16,609 patients who had received iLM3 extraction under ambulatory settings were retrieved for analysis. Outcomes of interest included dry socket (DS), prolonged temporomandibular joint symptoms (TMD), and surgical site infection (SSI), which necessitated additional appointments to manage. Odds ratios of having those complications between different variables were analyzed. The incidence rates of DS, TMD, and SSI were 3.6%, 0.41%, 0.17%, respectively; while they ranged from 0.33–19.14% (DS), 0–4.17% (TMD), and 0.2–5.17% (SSI) in previous studies. Logistic regression revealed DS significantly correlated with complexity of odontectomy (2.5-fold of risk) and history of gingivitis or pericoronitis (1.3-fold of risk). More TMD was found in female than male patients (0.5% versus 0.3%). However, no factors associated with SSI was found; neither did we find aging as a risk in association with any of above complications. Compared to previous studies, our data supports that surgical intervention should be considered in iLM3 with risk of gingivitis or pericoronitis to reduce the occurrence of DS. The original information in this article, which provides a “real-world” evidence, along with the organizing data we summarized from previous article, can serve as a reference for clinicians in assessing the complication risks before treatment of iLM3.
Mental fatigue prediction during eye-typing
Authors: Bafna Tanya , Bækgaard Per , Hansen John Paulin
Published: February 2021

Mental fatigue is a common problem associated with neurological disorders. Until now, there has not been a method to assess mental fatigue on a continuous scale. Camera-based eye-typing is commonly used for communication by people with severe neurological disorders. We designed a working memory-based eye-typing experiment with 18 healthy participants, and obtained eye-tracking and typing performance data in addition to their subjective scores on perceived effort for every sentence typed and mental fatigue, to create a model of mental fatigue for eye-typing. The features of the model were the eye-based blink frequency, eye height and baseline-related pupil diameter. We predicted subjective ratings of mental fatigue on a six-point Likert scale, using random forest regression, with 22% lower mean absolute error than using simulations. When additionally including task difficulty (i.e. the difficulty of the sentences typed) as a feature, the variance explained by the model increased by 9%. This indicates that task difficulty plays an important role in modelling mental fatigue. The results demonstrate the feasibility of objective and non-intrusive measurement of fatigue on a continuous scale.
Circulating microparticles and activated platelets as novel prognostic biomarkers in COVID-19; relation to cancer
Authors: Zahran Asmaa M. , El-Badawy Omnia , Ali Wageeh A. , Mahran Zainab Gaber , Mahran Essam Eldeen M. O. , Rayan Amal
Published: February 2021

Background and aim

The study aimed to determine whether the MPs levels and platelet activation are affected by the COVID-19 infection in both malignant and non-malignant patients compared to healthy individuals and define their contribution to the COVID-19 associated coagulopathy and the relation of these MPs to other hematologic parameters.

Patients and methods

We recruited 23 malignant patients with reverse transcription polymerase chain reaction (RT-PCR) positive COVID-19, also, 19 COVID-19 non-malignant patients, and 20 healthy volunteers were also enrolled for comparison. Blood samples were collected from patients and healthy donors into 5 mL vacutainer tube containing 3.5% buffered sodium citrate solution for measurement of total microparticles (TMPs), platelet microparticles (PMPs), endothelial microparticles (EMPs), CD62 activated platelets, and CD41 platelet marker.

Results

COVID-19 malignant patients had significantly lower hemoglobin and platelets compared to COVID non-malignant ones, while they had significantly higher C-reactive protein, LDH, AST, Albunim, creatinine, and prognostic index (PI) compared to COVID-19 non-malignant patients. significant accumulations of TMPs, PMPs, EMPs, and activated platelets in COVID-19 affected patients compared to healthy controls. TMPs, and EMPs were significantly accumulated in COVID-19 malignant compared to COVID-19 non-malignant patients with no significant difference in PMPs between both.

Conclusion

Circulating MPs and activated platelets may be promising novel prognostic biomarkers capable of identifying potentially severe COVID-19 patients who require immediate care especially in cancer patients.
Biomonitorization of concentrations of 28 elements in serum and urine among workers exposed to indium compounds
Authors: Liu Nan , Guan Yi , Li Bin , Yao Sanqiao
Published: February 2021

Many studies have documented the abnormal concentrations of metals/metalloids in serum or urine of occupational workers, but no works systematically analysed the concentrations of elements in serum or urine of indium-exposed workers. This study was aimed to assess 28 elements in serum and urine from 57 individuals with occupational exposure to indium and its compounds. Control subjects were 63 workers without metal exposure. We collected information on occupation and lifestyle habits by questionnaire. Biological samples were collected to quantify elements by inductive coupled plasma-mass spectrometer. Air in the breathing zones was drawn at flow rates of 1.5–3 L/min for a sampling period of 6 to 8 h, using a Model BFC-35 pump. The average ambient indium level was 0.078 mg/m3. Serum/urine Indium levels were significantly higher in indium-exposed workers than in controls (P < 0.01). Moreover, serum/urine indium concentrations in the group with 6–14 years and ≥15 years of employment were significantly higher than those with ≤5 employment years(P < 0.05). Ten of the other 27 elements/metals measured were higher in serum/urine in indium-exposed workers compared to the controls (aluminum, beryllium, cadmium, cesium, chromium, lithium, manganese, magnesium, molybdenum and vanadium). Zinc levels in serum/urine were significantly decreased in the indium-exposed workers. Additionally, other elements/metals were higher in one specimen (serum or urine) but lower in the other (Selenium was lower in serum but higher in urine in the indium-exposed workers compared with the controls; likewise Thallium and Rubidium were higher in serum but lower in urine). Linear regression analyses, revealed significant correlations between serum and urine for indium, aluminum, arsenic, barium, cadmium, cesium, cobalt, selenium, silver, and zinc (P < 0.05). These data suggest that occupational exposure to indium and its compounds may disturb the homeostasis of trace elements in systemic circulation, indium concentrations in serum or urine appear reflective of workers’ exposure to ambient indium and their years of working, respectively. The serum/urine levels of essential metals are modified by exposure to indium in occupationally exposed workers. Further studies including larger sample size and more kinds of biological sample are needed to validate our findings.
Prediction model for best focus, power, and spherical aberration of the cornea: Raytracing on a large dataset of OCT data
Authors: Langenbucher Achim , Szentmáry Nóra , Weisensee Johannes , Wendelstein Jascha , Cayless Alan , Menapace Rupert , Hoffmann Peter
Published: February 2021

Purpose

To analyse corneal power based on a large optical coherence tomography dataset using raytracing, and to evaluate corneal power with respect to the corneal front apex plane for different definitions of best focus.

Methods

A large OCT dataset (10,218 eyes of 8,430 patients) from the Casia 2 (Tomey, Japan) was post-processed in MATLAB (MathWorks, USA). Using radius of curvature, corneal front and back surface asphericity, central corneal thickness, and pupil size (aperture) a bundle of rays was traced through the cornea. Various best focus definitions were tested: a) minimum wavefront error, b) root mean squared ray scatter, c) mean absolute ray scatter, and d) total spot diameter. All 4 target optimisation criteria were tested with each best focus plane. With the best-fit keratometer index the difference of corneal power and keratometric power was evaluated using a multivariate linear model.

Results

The mean corneal powers for a/b/c/d were 43.02±1.61/42.92±1.58/42.91±1.58/42.94±1.59 dpt respectively. The root mean squared deviations of corneal power from keratometric power (nK = 1.3317/1.3309/1.3308/1.3311 for a/b/c/d) were 0.308/0.185/0.171/0.209 dpt. With the multivariate linear model the respective RMS error was reduced to 0.110/0.052/0.043/0.065 dpt (R² = 0.872/0.921/0.935/0.904).

Conclusions

Raytracing improves on linear Gaussian optics by considering the asphericity of both refracting surfaces and using Snell’s law of refraction in preference to paraxial simplifications. However, there is no unique definition of best focus, and therefore the calculated corneal power varies depending on the definition of best focus. The multivariate linear model enabled more precise estimation of corneal power compared to the simple keratometer equation.
Prevalence of intestinal parasite infections and associated risk factors among patients of Jimma health center requested for stool examination, Jimma, Ethiopia
Authors: Belete Yohannes Alemu , Kassa Tilahun Yemane , Baye Minale Fekadie
Published: February 2021

Background

Intestinal parasitic infections are still a serious public health problem in poor and developing countries like Ethiopia. Local epidemiological data is crucial to design and monitor prevention and control strategies. This study aimed to determine the prevalence of intestinal parasite infections and associated risk factors among patients requested for stool examination at Jimma health center, Southwest, Ethiopia.

Methods

A cross-sectional study was conducted among a total of 384 patients in Jimma health center, Southwest, Ethiopia. Stool samples were collected and examined using direct wet-mount and formal-ether concentration techniques. Data were analyzed using the Chi-Square (X2) test and SPPS Version 24 and P Value<0.05 was considered for statistically significance.

Results

The overall prevalence of intestinal parasite infections was found to be 79(20.6%). The infection rate was slightly higher in females 261(68%) than in males 123(32%). Eight types of intestinal parasites were identified and the highest prevalence was Giardia lamblia 25(6.5%) followed by A. lumbricoides 22(5.7%). Single parasitic infection was found among 67(17.4%) of the patients and double infection was 12(3.1%). Shoe wearing habits, Status of fingernail, Handwashing before a meal and after defecation, Source of water for bathing and drinking were significant factors(p<0.05) for intestinal parasitic infection.

Conclusion

A relatively low prevalence of intestinal parasite infections was observed among patients of Jimma health center requested for the stool examination.
Ecological and reproductive characteristics of holothuroids Isostichopus badionotus and Isostichopus sp. in Colombia
Authors: Acosta Ernesto J. , Rodríguez-Forero Adriana , Werding Bernd , Kunzmann Andreas
Published: February 2021

Isostichopus badionotusandIsostichopussp. are two holothuroids exploited in the Caribbean region of Colombia. Until recently, they were considered a single species. During one year, 222 individuals ofIsostichopussp. and 114 ofI.badionotuswere collected in two bays of the Santa Marta region to study their reproductive biology and collect information on their size, weight and habitat. Both sea cucumber morphotypes showed an annual reproductive cycle, with a reproductive season from September to November, closely related to the increase in water temperature and rainfall. In both sea cucumbers the population structure exhibited a unimodal distribution composed of mature individuals and a sex ratio of 1:1.Isostichopussp. had an average size and weight (193 ± 52 mm and 178 ± 69 g) and size and weight at first maturity (175 mm and 155 g) that was much lower thanI.badionotus(respectively, 324 ± 70 mm and 628 ± 179 g; 220 mm and 348 g). While 98% ofIsostichopussp. individuals were collected in the upper 2.5 m, on rocky bottoms between cracks, 73% ofI.badionotusindividuals were found between 3 and 7.8 m depth, exposed on sandy bottoms. These differences imply that management measures (e.g. minimum catch size) should not be the same for both sea cucumbers morphotypes.
Metabolic networks of plasma and joint fluid base on differential correlation
Authors: Xu Bingyong , Su Hong , Wang Ruya , Wang Yixiao , Zhang Weidong
Published: February 2021

Whether osteoarthritis (OA) is a systemic metabolic disorder remains controversial. The aim of this study was to investigate the metabolic characteristics between plasma and knee joint fluid (JF) of patients with advanced OA using a differential correlation metabolic (DCM) networks approach. Plasma and JF were collected during the joint replacement surgery of patients with knee OA. The biological samples were pretreated with standard procedures for metabolite analysis. The metabolic profiling was conducted by means of liquid mass spectrometry coupled with a AbsoluteIDQ kit. A DCM network approach was adopted for analyzing the metabolomics data between the plasma and JF. The variation in the correlation of the pairwise metabolites was quantified across the plasma and JF samples, and networks analysis was used to characterize the difference in the correlations of the metabolites from the two sample types. Core metabolites that played an important role in the DCM networks were identified via topological analysis. One hundred advanced OA patients (50 men and 50 women) were included in this study, with an average age of 65.0 ± 7.6 years (65.6 ± 7.1 years for females and 64.4 ± 8.1 years for males) and a mean BMI of 32.6 ± 5.8 kg/m2 (33.4 ± 6.3 kg/m2 for females and 31.7 ± 5.3 kg/m2 for males). Age and BMI matched between the male and female groups. One hundred and forty-five nodes, 567 edges, and 131 nodes, 407 edges were found in the DCM networks (p < 0.05) of the female and male groups, respectively. Six metabolites in the female group and 5 metabolites in the male group were identified as key nodes in the network. There was a significant difference in the differential correlation metabolism networks of plasma and JF that may be related to local joint metabolism. Focusing on these key metabolites may help uncover the pathogenesis of knee OA. In addition, the differential metabolic correlation between plasma and JF mostly overlapped, indicating that these common correlations of pairwise metabolites may be a reflection of systemic characteristics of JF and that most significant correlation variations were just a result of "housekeeping” biological reactions.
Convergent antibody evolution and clonotype expansion following influenza virus vaccination
Authors: Forgacs David , Abreu Rodrigo B. , Sautto Giuseppe A. , Kirchenbaum Greg A. , Drabek Elliott , Williamson Kevin S. , Kim Dongkyoon , Emerling Daniel E. , Ross Ted M.
Published: February 2021

Recent advances in high-throughput single cell sequencing have opened up new avenues into the investigation of B cell receptor (BCR) repertoires. In this study, PBMCs were collected from 17 human participants vaccinated with the split-inactivated influenza virus vaccine during the 2016–2017 influenza season. A combination of Immune Repertoire Capture (IRCTM) technology and IgG sequencing was performed on ~7,800 plasmablast (PB) cells and preferential IgG heavy-light chain pairings were investigated. In some participants, a single expanded clonotype accounted for ~22% of their PB BCR repertoire. Approximately 60% (10/17) of participants experienced convergent evolution, possessing public PBs that were elicited independently in multiple participants. Binding profiles of one private and three public PBs confirmed they were all subtype-specific, cross-reactive hemagglutinin (HA) head-directed antibodies. Collectively, this high-resolution antibody repertoire analysis demonstrated the impact evolution can have on BCRs in response to influenza virus vaccination, which can guide future universal influenza prophylactic approaches.
Association of soluble urokinase plasminogen activator receptor levels with fibrotic and vascular manifestations in systemic sclerosis
Authors: Butt Sheraz , Jeppesen Jørgen L. , Iversen Line Vinderslev , Fenger Mogens , Eugen-Olsen Jesper , Andersson Charlotte , Jacobsen Søren
Published: February 2021

Objective

We assessed the association of suPAR (soluble urokinase plasminogen activator receptor) plasma levels with fibrotic and vascular manifestations in patients with systemic sclerosis (SSc).

Methods

suPAR plasma levels were measured in 121 consecutive patients with SSc and correlated to pulmonary and vascular features of SSc, including interstitial lung disease as characterized by percentage of predicted CO diffusing capacity (DLco) and forced vital capacity (FVC), pulmonary fibrosis by computed tomography, and pulmonary arterial hypertension, telangiectasias, and digital ulcers.

Results

Overall, 121 SSc patients (84% females; mean age, 57 ± 12 [range: 22–79] years) were enrolled; 35% had diffuse cutaneous SSc. suPAR plasma levels ranged from 1.3–10.2 [median: 2.9 (p25–p75: 2.3–3.9)] ng/mL. Log(suPAR) levels correlated with DLco (r = -0.41,p<0.0001) and FVC (r = -0.26,p= 0.004), also when adjusted for age, sex, and pulmonary hypertension. A suPAR cut-off level of >2.5 ng/mL showed a sensitivity of 91% for identifying patients with either DLco <50% or FVC < 60% of the predicted values. Similarly, 19 (90%) had a suPAR >2.5 ng/mL among those diagnosed with pulmonary fibrosis vs. 59 (60%) among those who did not (p= 0.008). suPAR values were not associated with vascular manifestations.

Conclusion

suPAR levels strongly correlated with pulmonary involvement in SSc. Future studies should test if suPAR estimation can be used for surveillance of severe pulmonary involvement in SSc.
Characteristics of sickle cell patients with frequent emergency department visits and hospitalizations
Authors: Kidwell Kyle , Albo Camila , Pope Michael , Bowman Latanya , Xu Hongyan , Wells Leigh , Barrett Nadine , Patel Niren , Allison Amy , Kutlar Abdullah
Published: February 2021

Vaso-occlusive episodes (VOEs) are a hallmark of sickle cell disease (SCD), and account for >90% of health care encounters for this patient population. The Cooperative Study of Sickle Cell Disease, a large study enrolling >3000 patients, showed that the majority of SCD patients (80%) experienced 0–3 major pain crises/year. Only a small minority (~5%) experienced ≥6 VOEs/year. Our study sought to further understand this difference in VOE frequency between SCD patients. We analyzed 25 patients (13M/12F, mean age of 28.8) with ≥6 ED visits or hospitalizations/year (high utilizers), and compared these with 9 patients (6M/3F, mean age of 37.6) who had ≤2 ED visits or hospitalizations/year (low utilizers). All subjects were given a demographic survey along with questionnaires for depression, anxiety, and Health Locus of Control. Each subject then underwent quantitative sensory testing (QST) with three different modalities: pressure pain sensitivity, heat and cold sensitivity, and Von Frey monofilament testing. Laboratory and clinical data were collected through subjects’ medical records. CBC and chemistry analysis showed high utilizers had higher WBC (p<0.01), ANC (p<0.01), total bilirubin (p = 0.02), and lower MCV (p = 0.03). Opioid use (morphine equivalents) over the past 6 months was significantly higher in the high utilizer group (12125.7 mg vs 2423.1 mg, p = 0.005). QST results showed lower pressure pain threshold at the ulna (224.4 KPa vs 338.9 KPa, p = 0.04) in the high utilizer group. High utilizers also had higher anxiety (9.0 vs 4.6, p = 0.04) and depression scores (10.0 vs 6.0, p = 0.051). While the low utilizer group had higher education levels with more associate and bachelor degrees (p = 0.009), there was no difference in income or employment. These data show that many biological and psychosocial factors contribute to high health care utilization in SCD. A multi-disciplinary and multi-faceted approach will be required to address this complex problem.