bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling of optical fiber dispersion on QAM protocol in affordable RF-over-fiber channels
Authors: Granot Er’el
Published: February 2021

We investigate the effect of optical chromatic dispersion on ordinary double-sided modulation (DSM) quadrature amplitude modulation (QAM-M) protocol in RF-over-fiber (RFOF) channels. QAM-M protocol is common in RFOF communications channels. An analytical expression was derived for the channel’s response, the standard deviation of the QAM’s clusters, and for the estimations of the channel’s bit error rate (BER). The main findings are as follows: (A) unlike single-sided modulation (SSM) QAM or coherent QAM, ordinary DS QAM is governed by three length scales, and therefore it is much more susceptible to dispersion; (B) the QAM’s clusters cannot be bounded, even for weak dispersion, and therefore, zero-error detection is unattainable without dispersion compensation; and (C) a linear dispersion compensation filter was derived to mitigate the dispersion effects post-detection. These results suggest that it is not essential to operate the channel in a SSM QAM mode. A simpler and affordable option may be to operate the channel in an ordinary DSM QAM method and to apply a dispersion compensating filter in the electrical or even in the digital domain. This method is a low-cost solution to improve substantially the RFOF channels performances.
Axial accuracy and signal enhancement in acoustic-resolution photoacoustic microscopy by laser jitter effect correction and pulse energy compensation
Authors: Asadollahi Amir , Latifi Hamid , Pramanik Manojit , Qazvini Hamed , Rezaei Ali , Nikbakht Hamed , Abedi Abolfazl
Published: February 2021

In recent years, photoacoustic imaging has found vast applications in biomedical imaging. Photoacoustic imaging has high optical contrast and high ultrasound resolution allowing deep tissue non-invasive imaging beyond the optical diffusion limit. Q-switched lasers are extensively used in photoacoustic imaging due to the availability of high energy and short laser pulses, which are essential for high-resolution photoacoustic imaging. In most cases, this type of light source suffers from pulse peak-power energy variations and timing jitter noise, resulting in uncertainty in the output power and arrival time of the laser pulses. These problems cause intensity degradation and temporal displacement of generated photoacoustic signals which in turn deteriorate the quality of the acquired photoacoustic images. In this study, we used a high-speed data acquisition system in combination with a fast photodetector and a software-based approach to capture laser pulses precisely in order to reduce the effect of timing jitter and normalization of the photoacoustic signals based on pulse peak-powers simultaneously. In the experiments, maximum axial accuracy enhancement of 14 µm was achieved in maximum-amplitude projected images on XZ and YZ planes with ±13.5 ns laser timing jitter. Furthermore, photoacoustic signal enhancement of 77% was obtained for 75% laser pulses peak-power stability.
Optical parametric amplification in silicon nitride waveguides for coherent Raman imaging
Authors: Lüpken Niklas M. , Würthwein Thomas , Boller Klaus-J. , Fallnich Carsten
Published: February 2021

We present tunable waveguide-based optical parametric amplification by four-wave mixing (FWM) in silicon nitride waveguides, with the potential to be set up as an all-integrated device, for narrowband coherent anti-Stokes Raman scattering (CARS) imaging. Signal and idler pulses are generated via FWM with only 3 nJ pump pulse energy and stimulated by using only 4 mW of a continuous-wave seed source, resulting in a 35 dB enhancement of the idler spectral power density in comparison to spontaneous FWM. By using waveguides with different widths and tuning the wavelength of the signal wave seed, idler wavelengths covering the spectral region from 1.1 µm up to 1.6 µm can be generated. The versatility of the chip-based FWM light source is demonstrated by acquiring CARS images.
Distributed optomechanical fiber sensing based on serrodyne analysis
Authors: Zaslawski Simon , Yang Zhisheng , Thévenaz Luc
Published: February 2021

Distributed measurement of forward stimulated Brillouin scattering (FSBS) attracted substantial attention for its ability to probe media surrounding optical fibers. Currently, all techniques extract the information from the FSBS-induced local energy transfer among distinct optical tones, this transfer being fundamentally sensitive to intensity perturbations imposed by nonlinear effects. Instead, here we propose to extract the local FSBS information by measuring the frequency shift of a short optical pulse subject to the phase chirp modulation caused by harmonic FSBS oscillation. In full contrast with existing techniques, the optical pulse is much shorter than the period of the acoustic oscillation, enabling ultrashort spatial resolutions, and its frequency shift is precisely probed by a standard Brillouin optical time-domain analyzer. The proposed technique is validated in both remote and integrally distributed sensing configurations, demonstrating spatial resolutions of 0.8 m and 2 m, respectively, substantially outperforming state-of-the-art techniques.
Imaging through unknown scattering media based on physics-informed learning
Authors: Zhu Shuo , Guo Enlai , Gu Jie , Bai Lianfa , Han Jing
Published: February 2021

Imaging through scattering media is one of the hotspots in the optical field, and impressive results have been demonstrated via deep learning (DL). However, most of the DL approaches are solely data-driven methods and lack the related physics prior, which results in a limited generalization capability. In this paper, through the effective combination of the speckle-correlation theory and the DL method, we demonstrate a physics-informed learning method in scalable imaging through an unknown thin scattering media, which can achieve high reconstruction fidelity for the sparse objects by training with only one diffuser. The method can solve the inverse problem with more general applicability, which promotes that the objects with different complexity and sparsity can be reconstructed accurately through unknown scattering media, even if the diffusers have different statistical properties. This approach can also extend the field of view (FOV) of traditional speckle-correlation methods. This method gives impetus to the development of scattering imaging in practical scenes and provides an enlightening reference for using DL methods to solve optical problems.
All-dielectric photonic crystal with unconventional higher-order topology
Authors: Wu Shiqiao , Jiang Bin , Liu Yang , Jiang Jian-Hua
Published: February 2021

Photonic crystals (PhCs) have been demonstrated as a versatile platform for the study of topological phenomena. The recent discovery of higher-order topological insulators introduces new aspects of topological PhCs that are yet to be explored. Here, we propose an all-dielectric PhC with an unconventional higher-order band topology. Besides the conventional spectral features of gapped edge states and in-gap corner states, topological band theory predicts that the corner boundary of the higher-order topological insulator hosts a 2/3 fractional charge. We demonstrate that in the PhC such a fractional charge can be verified from the local density-of-states of photons, through the concept of local spectral charge as an analog of the local electric charge due to the band filling anomaly in electronic systems. Furthermore, we show that by introducing a disclination in the proposed PhC, localized states and a 2/3 fractional spectral charge emerge around the disclination core. The emergence of the fractional spectral charges and topological boundary modes here, however, is distinct from the known cases; particularly by the 2/3 fractional spectral charges and the unique topological indices. The predicted effects can be readily observed in the state-of-the-art experiments and may lead to potential applications in integrated and quantum photonics.
Self-Sovereign Identity als Grundlage für universell einsetzbare digitale Identitäten
Authors: Ehrlich Tobias , Richter Daniel , Meisel Michael , Anke Jürgen
Published: February 2021

In diesem Beitrag werden die Rolle digitaler Identitäten für eine funktionierende digitale Wirtschaft thematisiert und Anforderungen an das Management digitaler Identitäten abgeleitet. Bislang hat sich kein Ansatz für das Management digitaler Identitäten in der Breite etabliert, was zu einer Fragmentierung der ID-Landschaft sowie einer Vielzahl von Benutzerkonten für den Anwender führt. Mangels Standards ist zudem die Interoperabilität von digitalen Identitäten eingeschränkt. Dies führt zu einer Reihe von Problemen, die den effizienten und sicheren Umgang mit digitalen Identitäten behindern. Abhilfe verspricht das Konzept der Self-Sovereign Identities (SSI) und den damit verbundenen Standards „Verifiable Credentials“ und „Decentralized Identifiers“. Sie erlauben den flexiblen Austausch von manipulationssicheren digitalen Nachweisen zwischen Benutzern und Systemen und bilden damit die Grundlage für den Aufbau von Vertrauensbeziehungen im digitalen Raum. In diesem Beitrag werden das SSI-Paradigma vorgestellt und die Hürden diskutiert, die dem breitenwirksamen Einsatz dieses Konzepts entgegenstehen. Damit erhält der Leser einen kompakten Überblick verschiedener Ansätze für das Identitätsmanagement und die Potenziale selbst-souveräner Identitäten. Für die Gestaltung digitaler Dienste in Wirtschaft und Verwaltung sollte dieser Ansatz stärker berücksichtigt werden, um von den damit verbundenen Vorteilen zu profitieren.
Nonlinear effects of intrinsic dynamics on temporal encoding in a model of avian auditory cortex
Authors: Fehrman Christof , Robbins Tyler D. , Meliza C. Daniel
Published: February 2021

Neurons exhibit diverse intrinsic dynamics, which govern how they integrate synaptic inputs to produce spikes. Intrinsic dynamics are often plastic during development and learning, but the effects of these changes on stimulus encoding properties are not well known. To examine this relationship, we simulated auditory responses to zebra finch song using a linear-dynamical cascade model, which combines a linear spectrotemporal receptive field with a dynamical, conductance-based neuron model, then used generalized linear models to estimate encoding properties from the resulting spike trains. We focused on the effects of a low-threshold potassium current (KLT) that is present in a subset of cells in the zebra finch caudal mesopallium and is affected by early auditory experience. We found that KLT affects both spike adaptation and the temporal filtering properties of the receptive field. The direction of the effects depended on the temporal modulation tuning of the linear (input) stage of the cascade model, indicating a strongly nonlinear relationship. These results suggest that small changes in intrinsic dynamics in tandem with differences in synaptic connectivity can have dramatic effects on the tuning of auditory neurons.
The lymphatic system as a potential mechanism of spread of melioidosis following ingestion of Burkholderia pseudomallei
Authors: Nelson Michelle , Nunez Alejandro , Ngugi Sarah A. , Atkins Timothy P.
Published: February 2021

Burkholderia pseudomalleiis the causative agent of melioidosis, which is a Gram negative, facultative intracellular bacterium. Disease is prevalent in SE Asia and in northern Australia, as well as in other tropical and subtropical regions. Recently, there is an increasing awareness of the importance of bacterial ingestion as a potential route of infection, particularly in cases of unexplained origin of the disease. The marmoset is a New World Monkey (NWM) species that is being developed as an alternative NHP model to complement the more traditionally used Old World Monkeys (OWM). Models have been developed for the traditional routes of disease acquisition, subcutaneous and inhalational. This manuscript details the development and characterisation of an ingestion model of melioidosis. Dose-ranging study assessed the lethality ofB.pseudomalleiand disease progression was assessed by euthanizing animals at predetermined time points, 12, 36, 48 and 54 hours post-challenge. Challenge doses of greater than 6.2 x 106cfu resulted in an acute, lethal, febrile disease. Following challenge the lung was the first organ, outside of the gastrointestinal tract, to become colonised. Enteritis (duodenitis, ileitis and/or jejunitis) was observed in sections of the small intestine from animals that succumbed to disease. However, the most severe pathological features were observed in the mesenteric lymph nodes from these animals. These findings are consistent with lymphatic draining as route of dissemination.
Immune response dynamics and Lutzomyia longipalpis exposure characterize a biosignature of visceral leishmaniasis susceptibility in a canine cohort
Authors: Solcà Manuela da Silva , Arruda Maiara Reis , Leite Bruna Martins Macedo , Mota Tiago Feitosa , Rebouças Miriam Flores , de Jesus Matheus Silva , Amorim Leila Denise Alves Ferreira , Borges Valéria Matos , Valenzuela Jesus , Kamhawi Shaden , Veras Patrícia Sampaio Tavares , Fraga Deborah Bittencourt Mothé , Brodskyn Claudia Ida
Published: February 2021

Background

Reports have shown correlations between the immune response to vector saliva and Leishmaniasis outcome. We followed dogs in an endemic area for two years characterizing resistance or susceptibility to canine visceral leishmaniasis (CVL) according to Leishmania infantum diagnosis and clinical development criteria. Then, we aimed to identify a biosignature based on parasite load, serum biological mediators’ interactions, and vector exposure intensity associated with CVL resistance and susceptibility.

Methodology/Principal findings

A prospective two-year study was conducted in an area endemic for CVL. Dogs were evaluated at 6-month intervals to determine infection, clinical manifestations, immune profile, and sandfly exposure. CVL resistance or susceptibility was determined upon the conclusion of the study. After two years, 78% of the dogs were infected with L. infantum (53% susceptible and 47% resistant to CVL). Susceptible dogs presented higher splenic parasite load as well as persistence of the parasite during the follow-up, compared to resistant ones. Susceptible dogs also displayed a higher number of correlations among the investigated biological mediators, before and after infection diagnosis. At baseline, anti-saliva antibodies, indicative of exposure to the vector, were detected in 62% of the dogs, reaching 100% in one year. Higher sandfly exposure increased the risk of susceptibility to CVL by 1.6 times (CI: 1.11–2.41). We identified a discriminatory biosignature between the resistant and susceptible dogs assessing splenic parasite load, interaction of biological mediators, PGE2 serum levels and intensity of exposure to sandfly. All these parameters were elevated in susceptible dogs compared to resistant animals.

Conclusions/Significance

The biosignature identified in our study reinforces the idea that CVL is a complex multifactorial disease that is affected by a set of factors which are correlated and, for a better understanding of CVL, should not be evaluated in an isolated way.
Gene expression patterns associated with Leishmania panamensis infection in macrophages from BALB/c and C57BL/6 mice
Authors: Restrepo Carlos M. , Llanes Alejandro , Herrera Lizzi , Ellis Esteban , Lleonart Ricardo , Fernández Patricia L.
Published: February 2021

Leishmaniaparasites can trigger different host immune responses that result in varying levels of disease severity. The C57BL/6 and BALB/c mouse strains are among the host models commonly used for characterizing the immunopathogenesis ofLeishmaniaspecies and the possible antileishmanial effect of novel drug candidates. C57BL/6 mice tend to be resistant toLeishmaniainfections, whereas BALB/c mice display a susceptible phenotype. Studying species-specific interactions betweenLeishmaniaparasites and different host systems is a key step to characterize and validate these models forin vivostudies. Here, we use RNA-Seq and differential expression analysis to characterize the transcriptomic profiles of C57BL/6 and BALB/c peritoneal-derived macrophages in response toLeishmania panamensisinfection. We observed differences between BALB/c and C57BL/6 macrophages regarding pathways associated with lysosomal degradation, arginine metabolism and the regulation of cell cycle. We also observed differences in the expression of chemokine and cytokine genes associated with regulation of immune responses. In conclusion, infection withL.panamensisinduced an inflammatory gene expression pattern in C57BL/6 macrophages that is more consistently associated with a classic macrophage M1 activation, whereas in BALB/c macrophages a gene expression pattern consistent with an intermediate inflammatory response was observed.
In vitro and in vivo antibacterial activity assays of carvacrol: A candidate for development of innovative treatments against KPC-producing Klebsiella pneumoniae
Authors: de Souza Gleyce Hellen de Almeida , dos Santos Radai Joyce Alencar , Mattos Vaz Marcia Soares , Esther da Silva Kesia , Fraga Thiago Leite , Barbosa Leticia Spanivello , Simionatto Simone
Published: February 2021

Dissemination of carbapenem-resistant Klebsiella pneumoniae poses a threat to the successful treatment of bacterial diseases and increases the need for new antibacterial agents development. The objective of this study was to determine the antimicrobial activity of carvacrol against multidrug-resistant K. pneumoniae. Carbapenemase production was detected by MALDI-TOF. The PCR and sequencing showed that the blaKPC-2, blaOXA-48, blaNDM-1, blaCTX-M-8 genes were present in carbapenem-resistant K. pneumoniae strains. The polymyxin-resistant K. pneumoniae strain exhibited alterations in mgrB gene. The antimicrobial activity of carvacrol was evaluated in vitro using broth microdilution and time-kill methods. For this, carbapenem-resistant K. pneumoniae and polymyxin-resistant strains, were evaluated. The in vitro results showed that carvacrol had antimicrobial activity against all isolates evaluated. The survival curves showed that carvacrol eradicated all of the bacterial cells within 4 h. The antimicrobial effect of carvacrol in vivo was determined using a mouse model of infection with Klebsiella pneumoniae carbapenemase (KPC). The treatment with carvacrol was associated with increased survival, and significantly reduced bacterial load in peritoneal lavage. In addition, groups treated with carvacrol, had a significant reduction in the total numbers of white cell and significantly increased of platelets when compared to the untreated group. In vivo and in vitro studies showed that carvacrol regimens exhibited significant antimicrobial activity against KPC-producing K. pneumoniae, making it an interesting candidate for development of alternative treatments.
Detection of diverse carbapenem and multidrug resistance genes and high-risk strain types among carbapenem non-susceptible clinical isolates of target gram-negative bacteria in Kenya
Authors: Musila Lillian , Kyany’a Cecilia , Maybank Rosslyn , Stam Jason , Oundo Valerie , Sang Willie
Published: February 2021

Carbapenem-resistant gram-negative bacteria are an increasingly significant clinical threat globally. This risk may be underestimated in Kenya as only four carbapenemase genes in three bacterial species have been described. The study aimed to understand the antibiotic resistance profiles, genes, sequence types, and distribution of carbapenem-resistant gram-negative bacteria from patients in six hospitals across five Kenyan counties by bacterial culture, antibiotic susceptibility testing, and whole-genome sequence analysis. Forty-eight, non-duplicate, carbapenem non-susceptible, clinical isolates were identified across the five counties (predominantly in Nairobi and Kisii): twenty-seven Acinetobacter baumannii, fourteen Pseudomonas aeruginosa, three Escherichia coli, two Enterobacter cloacae, and two Klebsiella pneumoniae. All isolates were non-susceptible to β-lactam drugs with variable susceptibility to tigecycline (66%), minocycline (52.9%), tetracycline (29.4%), and levofloxacin (22.9%). Thirteen P. aeruginosa isolates were resistant to all antibiotics tested. Eleven carbapenemase genes were identified: blaNDM-1, blaOXA-23, -58, -66, -69, and -91 in A. baumannii (STs 1, 2, 164 and a novel ST1475), blaNDM-1 in E. cloacae (STs 25,182), blaNDM-1, blaVIM-1and -6, blaOXA-50 in P. aeruginosa (STs 316, 357, 654, and1203), blaOXA-181, blaNDM-1 in K. pneumoniae (STs 147 and 219), and blaNDM-5 in E. coli (ST164). Five A. baumannii isolates had two carbapenemases, blaNDM-1, and either blaOXA-23 (4) or blaOXA-58 (1). AmpC genes were detected in A. baumannii (blaADC-25), E. cloacae (blaDHA-1 and blaACT-6, 16), and K. pneumoniae (blaCMY). Significant multiple-drug resistant genes were the pan-aminoglycoside resistance16srRNA methyltransferase armA, rmtB, rmtC, and rmtF genes. This study is the first to report blaOXA-420, -58, -181, VIM-6, and blaNDM-5 in Kenyan isolates. High-risk STs of A. baumannii (ST1475, ST2), E. cloacae ST182, K. pneumoniae ST147, P. aeruginosa (ST357, 654), and E. coli ST167, ST648 were identified which present considerable therapeutic danger. The study recommends urgent carbapenem use regulation and containment of high-risk carbapenem-resistant bacteria.
Long-term maxillary anteroposterior changes following maxillary protraction with or without expansion: A meta-analysis and meta-regression
Authors: Lee Wei-Cheng , Shieh Yi-Shing , Liao Yu-Fang , Lee Cho-Hao , Huang Chiung Shing
Published: February 2021

Background

Maxillary protraction with or without expansion is a widely known orthopedic treatment modality in growing skeletal Class III patients. However, limited data are available regarding the outcomes of long-term changes in the maxilla. Aim of this meta-analysis was to assess the effectiveness of the long-term maxillary anteroposterior changes following a facemask therapy with or without rapid maxillary expansion in growing skeletal Class III patients.

Methods

A comprehensive literature search was conducted using the databases of PubMed, Science Direct, Web of Science, and Embase. Randomized controlled trials and cohort studies, published up to Sep. 2020, with maxillary protraction and/or expansion as keywords were included in this meta-analysis. Risk of bias within and across studies were assessed using the Cochrane tools (RoB2.0 and ROBINS-I) and GRADE approach. Overall and subgroup comparisons with the random-effect model were performed in this meta-analysis. Meta-regression models were designed to determine potential heterogeneity.

Results

There was a statistically significant increase (Mean difference, 2.29°; 95% confidence interval, 1.86–2.73; and p < 0.001 after facemask (FM) protraction. Mean difference, 1.73°; 95% confidence interval, 1.36–2.11; and p < 0.001 after rapid maxillary expansion(RME) and facemask protraction) in the Sella-Nasion-A point (SNA) angle in the treatment groups as compared with the control groups, when measured during the less than 3-year follow-up period. However, no statistically significant changes (Mean difference, 0.28°; 95% confidence interval, -0.57–1.13; and p = 0.52 after facemask protraction. Mean difference, 0.34°; 95% confidence interval, -0.64–1.33; and p = 0.50 after rapid maxillary expansion and facemask protraction) were observed in the SNA angle in the groups, when measured after 3 years of follow-up. Meta-regression analysis also showed that with increased follow-up duration, the effectiveness of maxillary protraction decreased.

Conclusion

This meta-analysis revealed that maxillary protraction therapy could be effective for a short-term in correcting maxillary hypoplasia and the treatment result was not affected by mean age and sex. However, with increased follow-up duration, the sagittal maxillary changes gradually decreased. Limitations on this review were only the SNA angle was used and clinical heterogeneity was not discussed. The quality of evidence was moderate. Further long-term observational studies are necessary for a comprehensive evaluation of the effects on maxillary skeletal changes.
Preterm disparities between foreign and Swedish born mothers depend on the method used to estimate gestational age. A Swedish population-based register study
Authors: Juárez Sol P. , Urquia Marcelo L. , Mussino Eleonora , Liu Can , Qiao Yao , Hjern Anders
Published: February 2021

This study aims to examine whether disparities in gestational age outcomes between foreign and Swedish-born mothers are contingent on the measure used to estimate gestational age and, if so, to identify which maternal factors are associated with the discrepancy. Using population register data, we studied all singleton live births in Sweden from 1992–2012 (n = 1,317,265). Multinomial logistic regression was performed to compare gestational age outcomes classified into very (<32 weeks) and late preterm (32–36 weeks), term and post-term derived from the last menstrual period (LMP) and ultrasound estimates in foreign- and Swedish-born women. Compared to Swedish-born women, foreign-born women had similar odds of very preterm birth (OR: 0.98 [95% CI: 0.98, 1.01]) and lower odds of moderately preterm birth (OR: 0.95 [95% CI: 0.92, 0.98]) based on ultrasound, while higher risks based on LMP (respectively, OR: 1.10 [95% CI: 1.07, 1.14] and 1.09 [95% CI: 1.06, 1.13]). Conclusions on disparities in gestational age-related outcomes by mother’s country of origin depend on the method used to estimate gestational age. Except for very preterm, foreign-born women had a health advantage when gestational age is based on ultrasound, but a health disadvantage when based on LMP. Studies assessing disparities in very preterm birth by migration status are not affected by the estimation method but caution should be taken when interpreting disparities in moderately preterm and preterm birth rates.
Observing COVID-19 related behaviors in a high visitor use area of Arches National Park
Authors: Miller Zachary D. , Freimund Wayne , Dalenberg Douglas , Vega Madison
Published: February 2021

Introduction

Visitation to parks and protected areas is a common COVID-19 coping strategy promoted by state and national public health officials and political leadership. Crowding and congestions in parks has been a perennial problem and the ability to socially distance within them is an unproven assumption. Is it possible to socially distance in a busy national park that has been designed to concentrate use?

Methodology/Principal findings

An observational study was conducted in July 2020 at the outside foyer of the Visitor Center of Arches National Park. Motion sensor cameras were placed to record one-minute videos when a person entered the field of view. Number of groups, group size, facial coverings and encounters within 6 feet (1.83 meters) of other groups were recorded. Groups were smaller on average than recorded in previous studies. Approximately 61% of the visitors wore masks. Most groups (69%) were able to experience the visitor center with no intergroup encounters. We model the probability of intergroup encounters and find as group size and number of groups increases, the probability of encounters rises. With four groups present, the probability of one or more encounters ranges from 19% to 40% for common group sizes, while if eight groups are present, the probability of one or more encounters increases from 34% to 64% for common group sizes.

Conclusions/Significance

Under conditions in which park visitors have the physical space to avoid close encounters with other groups they are taking advantage of the opportunity. Visitors are minimizing group size, wearing masks, and remaining socially distant. However, encounters increase as the number or the size of the groups increases. In other areas of the parks this ability to avoid encounters may not be as possible. We recommend that park managers continue to appeal for compliance with CDC guidelines, especially the wearing of masks and encouraging visitors to split up into small groups when visiting.
Image quality and diagnostic value of diffusion-weighted breast magnetic resonance imaging: Comparison of acquired and computed images
Authors: Ahn Hye Shin , Kim Sung Hun , Kim Ji Youn , Park Chang Suk , Grimm Robert , Son Yohan
Published: February 2021

Purpose

To compare the image quality of acquired diffusion-weighted imaging (DWI) and computed DWI and evaluate the lesion detectability and likelihood of malignancy in these datasets.

Materials and methods

This prospective study was approved by our institutional review board. A total of 29 women (mean age, 43.5 years) underwent DWI between August 2018 and April 2019 for 32 breast cancers and 16 benign breast lesions. Three radiologists independently reviewed the acquired DWI with b-values of 1000 and 2000 s/mm2 (A-b1000 and A-b2000) and the computed DWI with a b-value of 2000 s/mm2 (C-b2000). Image quality was scored and compared between the three DWI datasets. Lesion detectability was recorded, and the lesion’s likelihood for malignancy was scored using a five-point scale.

Results

The A-b1000 images were superior to the A-b2000 and C-b2000 images in chest distinction, fat suppression, and overall image quality. The A-b2000 and C-b2000 images showed comparable scores for all image quality parameters. C-b2000 showed the highest values for lesion detection among all readers, although there was no statistical difference in sensitivity, specificity, positive predictive value, negative predictive value, and accuracy between the DWI datasets. The malignancy scores of the DWI images were not significantly different among the three readers.

Conclusions

A-b1000 DWI is suitable for breast lesion evaluations, considering its better image quality and comparable diagnostic values compared to that of A-b2000 and C-b2000 images. The additional use of computed high b-value DWI may have the potential to increase the detectability of breast masses.
“Dispense antiretrovirals daily!” restructuring the delivery of HIV services to optimize antiretroviral initiation among men in Malawi
Authors: Nyondo-Mipando Alinane Linda , Kapesa Leticia Suwedi , Salimu Sangwani , Kazuma Thokozani , Mwapasa Victor
Published: February 2021

Background

Gender disparities exist in the scale-up and uptake of HIV services with men being disproportionately under-represented in the services. In Eastern and Southern Africa, of the people living with HIV infection, more adult women than men were on treatment highlighting the disparities in HIV services. Delayed initiation of antiretroviral treatment creates a missed opportunity to prevent transmission of HIV while increasing HIV and AIDS-associated morbidity and mortality. The main objective of this study was to assess the strategies that men prefer for Antiretroviral Therapy (ART) initiation in Blantyre, Malawi.

Methods

This was a qualitative study conducted in 7 Health facilities in Blantyre from January to July 2017. We selected participants following purposive sampling. We conducted 20 in-depth interviews (IDIs) with men of different HIV statuses, 17 interviews with health care workers (HCWs), and 14 focus group discussions (FGDs) among men of varying HIV statuses. We digitally recorded all the data, transcribed verbatim, managed using NVivo, and analysed it thematically.

Results

Restructuring the delivery of antiretroviral (ARVs) treatment and conduct of ART clinics is key to optimizing early initiation of treatment among heterosexual men in Blantyre. The areas requiring restructuring included: Clinic days by offering ARVs daily; Clinic hours to accommodate schedules of men; Clinic layout and flow that preserves privacy and establishment of male-specific clinics; ARV dispensing procedures where clients receive more pills to last them longer than 3 months. Additionally there is need to improve the packaging of ARVs, invent ARVs with less dosing frequency, and dispense ARVs from the main pharmacy. It was further suggested that the test-and-treat strategy be implemented with fidelity and revising the content in counseling sessions with an emphasis on the benefits of ARVs.

Conclusion

The success in ART initiation among men will require a restructuring of the current ART services to make them accessible and available for men to initiate treatment. The inclusion of people-centered approaches will ensure that individual preferences are incorporated into the initiation of ARVs. The type, frequency, distribution, and packaging of ARVs should be aligned with other medicines readily available within a health facility to minimize stigma.
Effect of inhibition indexed by auditory P300 on transmission of visual sensory information
Authors: Houshmand Chatroudi Amirmahmoud , Rostami Reza , Nasrabadi Ali Motie , Yotsumoto Yuko
Published: February 2021

Early electroencephalographic studies that focused on finding brain correlates of psychic events led to the discovery of the P300. Since then, the P300 has become the focus of many basic and clinical neuroscience studies. However, despite its wide applications, the underlying function of the P300 is not yet clearly understood. One line of research among the many studies that have attempted to elucidate the underlying subroutine of the P300 in the brain has suggested that the physiological function of the P300 is related to inhibition. While some intracranial, behavioral, and event-related potential studies have provided support for this theory, little is known about the inhibitory mechanism. In this study, using alpha event-related desynchronization (ERD) and effective connectivity, based on the causal (one-way directed) relationship between alpha ERD and P300 sources, we demonstrated that P300’s associated inhibition is implemented at a higher information processing stage in a localized brain region. We discuss how inhibition as the primary function of the P300 is not inconsistent with ’resource allocation’ and ’working memory updating’ theories about its cognitive function. In light of our findings regarding the scope and information processing stage of inhibition of the P300, we reconcile the inhibitory account of the P300 with working memory updating theory. Finally, based on the compensatory behavior of alpha ERD at the time of suppression of the P300, we propose two distinct yet complementary working memory mechanisms (inhibition and desynchronizing excitation) that render target perception possible.
The combination of MMSE with VSRAD and eZIS has greater accuracy for discriminating mild cognitive impairment from early Alzheimer’s disease than MMSE alone
Authors: Tokumitsu Keita , Yasui-Furukori Norio , Takeuchi Junko , Yachimori Koji , Sugawara Norio , Terayama Yoshio , Tanaka Nobuyuki , Naraoka Tatsunori , Shimoda Kazutaka
Published: February 2021

Background

Alzheimer’s disease (AD) is assessed by carefully examining a patient’s cognitive impairment. However, previous studies reported inadequate diagnostic accuracy for dementia in primary care settings. Many hospitals use the automated quantitative evaluation method known as the Voxel-based Specific Regional Analysis System for Alzheimer’s Disease (VSRAD), wherein brain MRI data are used to evaluate brain morphological abnormalities associated with AD. Similarly, an automated quantitative evaluation application called the easy Z-score imaging system (eZIS), which uses brain SPECT data to detect regional cerebral blood flow decreases associated with AD, is widely used. These applications have several indicators, each of which is known to correlate with the degree of AD. However, it is not completely known whether these indicators work better when used in combination in real-world clinical practice.

Methods

We included 112 participants with mild cognitive impairment (MCI) and 128 participants with early AD in this study. All participants underwent MRI, SPECT, and the Mini-Mental State Examination (MMSE). Demographic and clinical characteristics were assessed by univariate analysis, and logistic regression analysis with a combination of MMSE, VSRAD and eZIS indicators was performed to verify whether the diagnostic accuracy in discriminating between MCI and early AD was improved.

Results

The area under the receiver operating characteristic curve (AUC) for the MMSE score alone was 0.835. The AUC was significantly improved to 0.870 by combining the MMSE score with two quantitative indicators from the VSRAD and eZIS that assessed the extent of brain abnormalities.

Conclusion

Compared with the MMSE score alone, the combination of the MMSE score with the VSRAD and eZIS indicators significantly improves the accuracy of discrimination between patients with MCI and early AD. Implementing VSRAD and eZIS does not require professional clinical experience in the treatment of dementia. Therefore, the accuracy of dementia diagnosis by physicians may easily be improved in real-world primary care settings.
Mathematical modeling of COVID-19 transmission dynamics in Uganda: Implications of complacency and early easing of lockdown
Authors: Mugisha Joseph Y. T. , Ssebuliba Joseph , Nakakawa Juliet N. , Kikawa Cliff R. , Ssematimba Amos
Published: February 2021

Background

Uganda has a unique set up comprised of resource-constrained economy, social-economic challenges, politically diverse regional neighborhood and home to long-standing refuge crisis that comes from long and protracted conflicts of the great lakes. The devastation of the on-going global pandemic outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is likely to be escalated by these circumstances with expectations of the impact of the disease being severe.

Materials and methods

In this study, we formulate a mathematical model that incorporates the currently known disease characteristics and tracks various intervention measures that the government of Uganda has implemented since the reporting of the first case in March 2020. We then evaluate these measures to understand levels of responsiveness and adherence to standard operating procedures and quantify their impact on the disease burden. Novel in this model was the unique aspect of modeling the trace-and-isolate protocol in which some of the latently infected individuals tested positive while in strict isolation centers thereby reducing their infectious period.

Results

The study findings show that even with elimination of all imported cases at any given time it would take up to nine months to rid Uganda of the disease. The findings also show that the optimal timing of easing of lockdowns while mitigating the possibility of re-emergence of a second epidemic wave requires avoiding the scenario of releasing too-many-too-soon. It is even more worrying that enhancing contact tracing would only affect the magnitude and timing of the second wave but cannot prevent it altogether.

Conclusion

We conclude that, given the prevailing circumstances, a phased-out lifting of lockdown measures, minimization of COVID-19 transmissibility within hospital settings, elimination of recruitment of infected individuals as well as enhanced contact tracing would be key to preventing overwhelming of the healthcare system that would come with dire consequences.
Evaluation of ebselen in resolving a methicillin-resistant Staphylococcus aureus infection of pressure ulcers in obese and diabetic mice
Authors: Mohammad Haroon , Abutaleb Nader S. , Dieterly Alexandra M. , Lyle L. Tiffany , Seleem Mohamed N.
Published: February 2021

Pressure ulcers (PUs) are a source of morbidity in individuals with restricted mobility including individuals that are obese or diabetic. Infection of PUs with pathogens, including methicillin-resistantStaphylococcus aureus(MRSA), impairs ulcers from healing. The present study evaluated ebselen as a topical antibacterial to treat MRSA-infected PUs. Against two differentS.aureusstrains, including MRSA USA300, resistance to ebselen did not emerge after 14 consecutive passages. Resistance to mupirocin emerged after only five passages. Additionally, ebselen was found to exert a modest postantibiotic effect of five hours against two MRSA strains. Ebselen was subsequently evaluated in MRSA-infected PUs in two models using obese and diabetic mice. In obese mice, topical ebselen (89.2% reduction) and oral linezolid (84.5% reduction) similarly reduced the burden of MRSA in infected PUs. However, in diabetic mice, topical ebselen (45.8% reduction in MRSA burden) was less effective. Histopathological evaluation of ulcers in diabetic mice determined that ebselen treatment resulted in fewer bacterial colonies deep within the dermis and that the treatment exhibited evidence of epithelial regeneration. Topical mupirocin was superior to ebselen in reducing MRSA burden in infected PUs both in obese (98.7% reduction) and diabetic (99.3% reduction) mice. Ebselen’s antibacterial activity was negatively impacted as the bacterial inoculum was increased from 105CFU/mL to 107CFU/mL. These results suggest that a higher dose of ebselen, or a longer course of treatment, may be needed to achieve a similar effect as mupirocin in topically treating MRSA-infected pressure ulcers.
Visual outcomes and prognostic factors of vitrectomy for lamellar macular holes and epiretinal membrane foveoschisis
Authors: Omoto Takashi , Asahina Yuichi , Zhou Han Peng , Fujino Ryosuke , Takao Muneyuki , Obata Ryo , Inoue Tatsuya , Asaoka Ryo , Maruyama-Inoue Maiko , Yanagi Yasuo , Kadonosono Kazuaki
Published: February 2021

Purpose

To evaluate the visual outcomes of vitrectomy for lamellar macular hole (LMH) and epiretinal membrane (ERM) foveoschisis and to investigate the prognostic factor for postoperative visual acuity.

Methods

We retrospectively reviewed 15 LMH and 17 ERM foveoschisis eyes that had undergone a standard three-port pars plana vitrectomy with (12 eyes) or without (20 eyes) cataract surgery. Best-corrected visual acuity (BCVA) at postoperative three months and the final visit were compared to the preoperative measurements. We investigated the relationship between BCVA at the final visit and baseline parameters (age, preoperative BCVA, the presence of epiretinal proliferation [EP] and ellipsoid zone [EZ] disruption). The best explanatory variables for the final BCVA were investigated using the corrected Akaike information criterion (AICc) model selection.

Results

The mean age was 67.2 years. The mean follow-up duration was 30.7 months. Fifteen of 32 examined eyes were diagnosed as LMH and 17 eyes as ERM foveoschisis. Twelve eyes in LMH had EP and 13 eyes showed the disruption of EZ integrity. In total, BCVA significantly improved at 3 months postoperatively (p = 0.0013). A significant improvement was observed in ERM foveoschisis (p = 0.0085) but not in LMH group (p = 0.071). Comparing the BCVA between the baseline and the final visit, significant improvements were observed in total, ERM foveoschisis and LMH group (p<0.001, p<0.001 and p = 0.026, respectively). The optimal model for BCVA at the final visit included preoperative BCVA and the presence of EZ disruption (p<0.001 and p<0.001, respectively).

Conclusion

Our results suggested that the final BCVA was dependent on preoperative BCVA and the presence of EZ disruption. Surgical indications might be warranted for LMHs with EZ disruption.
A Preliminary List of References for an Unrealized Project at the New Oslo Public Library
Authors: Guimarães Tamar
Published: February 2021

Listed references for a play in nine acts, on hospitality and its pitfalls, proposed as a public art project for the New Oslo Public Library. The project was not realized. The proposal was to run a series of participatory workshops for library users and library staff. The process would have concluded with the performance of a musical banquet where the final performances were only one aspect of the work instead of its most important part.
Investigation of Sarcocystis spp. in slaughtered cattle and sheep by peptic digestion and histological examination in Sulaimani Province, Iraq
Authors: Abdullah Shadan Hassan
Published: February 2021

Background and Aim: Sarcocystosis is a zoonotic infection caused by various species of Sarcocystis organisms with a worldwide geographic distribution. This study investigated the presence of Sarcocystis organisms in cattle and sheep slaughtered at an abattoir in Sulaimani Province in North Iraq.

Materials and Methods: A total of 130 muscle samples were collected during May, June, and July of 2020, including 80 samples from sheep and 50 samples from cattle. Samples were examined visually for macrosarcocysts. The peptic digestion method was used to analyze fresh muscle tissue samples for detecting microsarcocysts followed by microscopic examination. Furthermore, muscle samples were fixed and stained with hematoxylin and eosin for histopathological examination.

Results: In the gross examination, macroscopic cysts were not detected in both cattle and sheep; hence, all the prevalence data were obtained through microscopic observation of muscle samples. The peptic digestion method revealed the presence of banana-shaped bradyzoites in 90% and 92.5% of slaughtered cattle and sheep muscle samples, respectively. Organ-wise prevalence revealed that 95% and 92% of esophageal samples of sheep and cattle contained Sarcocystis spp., respectively. Moreover, 90% and 88% of sheep and cattle diaphragms were respectively infected. Histopathological examination of tissue sections revealed two morphologically distinct types of microsarcocysts, including thin-walled and thick-walled, in both sheep and cattle.

Conclusion: The suspected Sarcocystis spp. were Sarcocystis tenella and Sarcocystis arieticanis in sheep and Sarcocystis cruzi and Sarcocystis bovifelis or Sarcocystis hominis in cattle. Infective stages of different Sarcocystis spp. are widespread in the study area environment.
The West AfricanJihādMovements and the Islamic Legal Literature of the Southwestern Sahara (1650–1850)
Authors: Warscheid Ismail
Published: February 2021

This article explores debates among Muslim jurists on the question of politico-religious authority that developed in the southwestern Sahara during the age of the West African jihād movements. I argue that scholars in present-day Mauritania and northern Mali perceived the Fulbe Imamates of ‘Abd al-Qādir Kane (d. 1807) in Futa Tooro and of Aḥmad Lobbo (d. 1845) in Masina as a possibility for establishing a true Islamic polity in the region and ending the domination of Arabic-speaking nomadic groups, the Banū Ḥassān. The various concepts and notions put forward in these debates reflect the complex ways in which legal ideas were transmitted across time and space, while helping to shape discursive action in local contexts. As such, they document the emergence of autonomous and original traditions of legal reasoning among Muslim scholars in West Africa, and how these traditions connected to the juridical and religious culture of the Islamic ecumene.
“Africa Isn’t a Testing Lab”: Considering COVID Vaccine Trials in a History of Biomedical Experimentation and Abuse
Authors: Flint Karen
Published: February 2021

Contextualizing Africans’ skepticism of biomedicine from the colonial period, through the structural adjustment programs of the 1980s and 90s that slashed national healthcare budgets, the HIV/AIDS pandemic, the testing of pharmaceuticals in Africa, and the rising influence of global health is important for understanding both populist resistance and the caution of African biomedical doctors and researchers. Studying such histories might help avoid past problems related to clinical trials, rethink means to create more equitable relations within global health, and ensure African access to and use of any known remedies or vaccines regardless of their origins.