bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing thermal sensitivity using transient heat and cold stimuli combined with a Bayesian adaptive method in a clinical setting: A proof of concept study
Authors: Courtin Arthur S. , Maldonado Slootjes Sofia , Caty Gilles , Hermans Michel P. , Plaghki Léon , Mouraux André
Published: June 2020

Background

Quantitative sensory testing of thermal detection abilities is used as a clinical tool to assess the function of pain pathways. The most common procedure to assess thermal sensitivity, the ‘method of limits’, provides a quick but rough estimate of detection thresholds. Here, we investigate the potential of evaluating not only the threshold but also the slope of the psychometric functions for cold and warm detection.

Method

A convenience sample of 15 patients withdiabetes mellitus(DM) and 15 age‐matched healthy controls (HC) was tested. Thirty brief (100 ms) stimuli of each modality were applied to the volar wrist and foot dorsum. Cold and warm stimuli were delivered with a Peltier thermode and a temperature‐controlled CO2laser, respectively. Stimulus intensities were dynamically selected using an adaptive Bayesian algorithm (psi method) maximizing information gain for threshold and slope estimation. ROC analyses were used to assess the ability of slopes, thresholds and the combination of both to discriminate between groups.

Results

Assessment of the slope and threshold of the psychometric function for thermal detection took about 10 min. The ability to detect warmth was not reduced in DM patients as compared to HC. Cold detection performance assessed using slope or threshold parameters separated DM from HC with good discriminative power. Discrimination was further increased when both parameters were used together (93% sensitivity and 87% specificity), indicating that they provide complementary information on patient status.

Conclusion

The psi method may be an interesting alternative to the classical method of limits for thermal QST.

Significance

Current QST protocols provide an incomplete and potentially biased estimate of sensory detection performance. We propose a method that estimates the slope and the threshold of the psychometric function, defining heat and cold sensory detection performance, in only a few minutes. Furthermore, we provide preliminary evidence that combining slope and threshold parameters of cold detection performance leads to a better discriminative ability than relying solely on the threshold.
Channel incision by headcut migration: Reconnection of the Colorado River to its estuary and the Gulf of California during the floods of 1979–1988
Authors: Nelson Steven M. , Kendy Eloise , Flessa Karl W. , Rodríguez‐Burgueño J. Eliana , Ramírez‐Hernández Jorge , Rivas‐Salcedo Tomás E.
Published: June 2020

The macrotidal Colorado River Delta at the northern end of the Gulf of California in Mexico is hydrologically complex. We review historical accounts, data, field notes and photographs to evaluate the hydrological processes active on the delta prior to the advent of upstream dams. We also employ satellite imagery as well as recent LIDAR data to illustrate the critical role played by headcut erosion in restoring the river's fluvial/tidewater connection during the 1979–1988 floods. Prior to human manipulation, the river's contribution of fresh water to the Gulf was periodically interrupted by natural overflowing, avulsing, and flooding into the sub‐sea level Salton Sink on the north slope of the delta plain. River flow south towards the Gulf was also subject to occasional overflow into Laguna Salada, another sub‐sea level basin. In the mid‐20th century, the Delta was disconnected from its fluvial supply following installation of upstream dams and reservoirs. A tidal sediment obstruction developed in the estuary channel, forming a final barrier to fluvial connectivity. Release of Colorado River floodwaters into Mexico between 1979 and 1988 provided a natural experiment on the hydrological response of a long‐disconnected macrotidal delta to restoration of fluvial supply.
Autonomic dysreflexia triggered by breastfeeding in a non‐plegic patient with syringomyelia: A case report
Authors: Anthoulakis Christos , Iordanidou Eirini , Theodoridis Theodoros
Published: June 2020

Non‐plegic post‐traumatic syringomyelia patients can develop autonomic dysreflexia triggered by breastfeeding.
MicroRNA alterations in neuropathologic cognitive disorders with an emphasis on dementia: Lessons from animal models
Authors: Bahlakeh Gozal , Gorji Ali , Soltani Hamid , Ghadiri Tahereh
Published: June 2020

Cognitive dysfunction is a state of losing or having difficulties in remembering, learning, focusing, or making decisions that impact individual healthy life. Small single‐stranded and nonprotein coding RNAs, microRNAs (miRNAs) participate actively in regulatory processes, incorporate cognitive signaling pathways, and intensely affect cognitive evolution. miRNAs exert their modification activities through translational or transcriptional processes. Reportedly, cognitive impairment and dementia are rising, especially in developing countries. Herein we provided a brief review of original studies addressing miRNA changes in the most common neurological diseases with a focus on dementia and Alzheimer's disease. It must be noted that an increase in the level of certain miRNAs but a decrease in other ones deteriorate cognitive performance. The current review revealed that induction of miR‐214‐3p, miR‐302, miR‐21, miR‐ 200b/c, miR‐207, miR‐132, miR‐188‐3p and 5p, and miR‐873 improved cognitive impairment in various cognitive tasks. On the other hand, intentionally lowering the level of miR‐34a, miR‐124, miR‐574, and miR‐191a enhanced cognitive function and memory. Synaptic dysfunction is a core cause of cognitive dysfunction; miRNA‐34, miRNA‐34‐c, miRNA‐124, miRNA‐188‐5p, miRNA‐210‐5p, miRNA‐335‐3p, and miRNA‐134 strongly influence synaptic‐related mechanisms. The downregulation of miRNA‐132 aggregates both amyloid and tau in tauopathy. Concerning the massive burden of neurological diseases worldwide, the future challenge is the translation of animal model knowledge into the detection of pathophysiological stages of neurocognitive disorders and designing efficient therapeutic strategies. While the delivery procedure of agomir or antagomir miRNAs into the brain is invasive and only applied in animal studies, finding a safe and specific delivery route is a priority.
Determining whether the effect of liraglutide on non‐alcoholic fatty liver disease depends on reductions in the body mass index
Authors: Shiomi Megumi , Tanaka Yoichi , Takada Tesshu , Otori Katsuya
Published: June 2020

Background and Aim

Non‐alcoholic fatty liver disease (NAFLD) initially presents as steatosis, which can progress to non‐alcoholic steatohepatitis (NASH), and often presents clinically alongside metabolic syndromes. Glucagon‐like peptide‐1 receptor agonists (GLP‐1 RAs) are regularly utilized to treat type 2 diabetes mellitus. The GLP‐1 RA—liraglutide—ameliorates liver enzymes, histological features, and liver fat content of patients with NASH. However, few studies have examined whether the effect of GLP‐1 RAs depends on changes in the patient's body mass index (BMI). Therefore, this retrospective study aimed to investigate whether the efficacy of liraglutide depended on the baseline BMI or a reduction in BMI.

Methods

Fifty‐five Japanese patients with type 2 diabetes mellitus and NAFLD who received liraglutide treatment for 24 weeks were assessed. The association between BMI and liver function or fibrosis was evaluated based on the aspartate aminotransferase, alanine aminotransferase, and fibrosis‐4 indices.

Results

We found that 24 weeks of liraglutide treatment improved liver function and fibrosis in patients with type 2 diabetes mellitus and NAFLD, regardless of BMI changes or obesity status.

Conclusions

Our findings provide important insight into the impact of BMI on liver function and fibrosis in patients with type 2 diabetes mellitus and NAFLD who are treated with liraglutide.
A tale of two cascades: promoting a standardized tool for monitoring progress in HIV prevention
Authors: Auerbach Judith D , Gerritsen Annette AM , Dallabetta Gina , Morrison Michelle , Garnett Geoffrey P
Published: June 2020

Introduction

To achieve significant progress in global HIV prevention from 2020 onward, it is essential to ensure that appropriate programmes are being delivered with high quality and sufficient intensity and scale and then taken up by the people who most need and want them in order to have both individual and public health impact. Yet, currently, there is no standard way of assessing this. Available HIV prevention indicators do not provide a logical set of measures that combine to show reduction in HIV incidence and allow for comparison of success (or failure) of HIV prevention programmes and for monitoring progress in meeting global targets. To redress this, attention increasingly has turned to the prospects of devising an HIV prevention cascade, similar to the now‐standard HIV treatment cascade; but this has proven to be a controversial enterprise, chiefly due to the complexity of primary prevention.

Discussion

We address a number of core issues attendant with devising prevention cascades, including: determining the population of interest and accounting for the variability and fluidity of HIV‐related risk within it; the fact that there are multiple HIV prevention methods, and many people are exposed to a package of them, rather than a single method; and choosing the final step (outcome) in the cascade. We propose two unifying models of prevention cascades‐one more appropriate for programme managers and monitors and the other for researchers and programme developers‐and note their relationship. We also provide some considerations related to cascade data quality and improvement.

Conclusions

The HIV prevention field has been grappling for years with the idea of developing a standardised way to regularly assess progress and to monitor and improve programmes accordingly. The cascade provides the potential to do this, but it is complicated and highly nuanced. We believe the two models proposed here reflect emerging consensus among the range of stakeholders who have been engaging in this discussion and who are dedicated to achieving global HIV prevention goals by ensuring the most appropriate and effective programmes and methods are supported.
Hypoglycemia is not a defining feature of metabolic crisis in mitochondrial 3‐hydroxy‐3‐methylglutaryl‐CoA synthase deficiency: Further evidence of specific biochemical markers which may aid diagnosis
Authors: Conlon Tracey A. , Fitzsimons Patricia E. , Borovickova Ingrid , Kirby Fidelma , Murphy Sinéad , Knerr Ina , Crushell Ellen
Published: June 2020

Mitochondrial 3‐hydroxy‐3‐methylglutaryl‐CoA (HMG Co‐A) synthase (mHS) deficiency is an autosomal recessive disorder of ketone body synthesis which has traditionally been associated with hypoketotic hypoglycemia, hepatomegaly and encephalopathy, presenting in early childhood following a period of fasting. We report the third case of mHS deficiency presenting in the absence of hypoglycemia, with profound biochemical abnormalities and further evidence of potential specific diagnostic biomarkers. A previously well, 20‐month old, unvaccinated male, of nonconsanguineous Polish heritage, presented with encephalopathy, hepatomegaly, severe metabolic acidosis, and mild hyperammonemia following a brief intercurrent illness. The patient was reported to have taken colloidal silver prior to presentation, posing a further diagnostic challenge. Additionally, he developed features suggestive of hemophagocytic lymphohistiocytosis during treatment. While the patient was normoglycemic prior to dextrose administration, the sample was markedly lipemic, with significant hypertriglyceridemia detected. Urine organic acid analysis revealed dicarboxylic aciduria with 4‐hydroxy‐6‐methyl‐2‐pyrone (4HMP) and the presence of three other previously reported putative biomarkers for mHS deficiency. Glutarate was markedly elevated in the initial chromatogram, with a mild increase in 3‐hydroxyglutarate (3HG) persisting. Raised acetylcarnitine was detected on acylcarnitine profile. Molecular genetic analysis of the HMGCS2 gene identified compound heterozygosity for known pathogenic mutations c.634G>A and c.1016+1G>A, confirming the diagnosis of mHS deficiency. This case provides further evidence that hypoglycemia is not invariably present in symptomatic mHS deficiency. We propose that elevated acetylcarnitine, triglycerides, and 3HG are additional biochemical features during acute presentations. With the expansion of novel biomarkers, further cases of this rare disorder may emerge.
Clinical characteristics and risk factors of mild‐to‐moderate COVID‐19 patients with false‐negative SARS‐CoV‐2 nucleic acid
Authors: Rong Yan , Wang Fei , Liu Jing , Zhou Yang , Li Xiaoli , Liang Xinhua , Zhang Dandan , Zeng Huadong , Wang Jing , Shi Yi
Published: June 2020

This study investigates the clinical and imaging characteristics of coronavirus disease 2019 (COVID‐19) patients with false‐negative nucleic acids. Mild‐to‐moderate COVID‐19 patients, including 19 cases of nucleic acid false‐negative patients and 31 cases of nucleic acid positive patients, were enrolled. Their epidemiological, clinical, and laboratory examination data and imaging characteristics were analyzed. Risk factors for false negatives were discussed. Compared with the nucleic acid positive group, the false‐negative group had less epidemiological exposure (52.6% vs 83.9%; P  = .025), less chest discomfort (5.3% vs 32.3%; P  = .035), and faster recovery (10 [8, 13] vs 15 [11, 18.5] days; P  = .005). The number of involved lung lobes was (2 [1, 2.5] vs 3 [2, 4] days; P  = .004), and the lung damage severity score was (3 [2.5, 4.5] vs 5 [4, 9] days; P  = .007), which was lighter in the nucleic acid false‐negative group. Thus, the absence of epidemiological exposure may be a potential risk factor for false‐negative nucleic acids. The false‐negative cases of COVID‐19 are worth noting because they have a risk of viral transmission without positive test results, lighter clinical manifestations, and less history of epidemiological exposure.
Simple nomogram based on initial laboratory data for predicting the probability of ICU transfer of COVID‐19 patients: Multicenter retrospective study
Authors: Zeng Zihang , Ma Yiming , Zeng Huihui , Huang Peng , Liu Wenlong , Jiang Mingyan , Xiang Xudong , Deng Dingding , Liao Xin , Chen Ping , Chen Yan
Published: June 2020

This retrospective, multicenter study investigated the risk factors associated with intensive care unit (ICU) admission and transfer in 461 adult patients with confirmed coronavirus disease 2019 (COVID‐19) hospitalized from 22 January to 14 March 2020 in Hunan, China. Outcomes of ICU and non‐ICU patients were compared, and a simple nomogram for predicting the probability of ICU transfer after hospital admission was developed based on initial laboratory data using a Cox proportional hazards regression model. Differences in laboratory indices were observed between patients admitted to the ICU and those who were not admitted. Several independent predictors of ICU transfer in COVID‐19 patients were identified including older age (≥65 years) (hazard ratio [HR] = 4.02), hypertension (HR = 2.65), neutrophil count (HR = 1.11), procalcitonin level (HR = 3.67), prothrombin time (HR = 1.28), and D‐dimer level (HR = 1.25). The lymphocyte count and albumin level were negatively associated with mortality (HR = 0.08 and 0.86, respectively). The developed model provides a means for identifying, at hospital admission, the subset of patients with COVID‐19 who are at high risk of progression and would require transfer to the ICU within 3 and 7 days after hospitalization. This method of early patient triage allows a more effective allocation of limited medical resources.
Molecular epidemiology and changes in genotype diversity of norovirus infections in acute gastroenteritis patients in Huzhou, China, 2018
Authors: Ji Lei , Hu Gang , Xu Deshun , Wu Xiaofang , Fu Yun , Chen Liping
Published: June 2020

Norovirus is an important causative agent of acute gastroenteritis worldwide, affecting people of all ages. Stool samples collected from patients with clinical symptoms of acute gastroenteritis in all age groups at the diarrhea outpatient department of the First People's Hospital in Huzhou were analyzed to gain insight into the prevalence and genetic characteristics of norovirus. From January to December 2018, a total of 551 specimens were screened for norovirus by real‐time reverse transcription‐polymerase chain reaction (RT‐PCR). RT‐PCR was used for genomic amplification and sequencing of the RNA‐dependent RNA polymerase and capsid gene of the positive samples. Genotypes of norovirus were assigned using the norovirus Noronet typing tool and phylogenetic analysis. About 100 (18.1%) specimens were identified as norovirus positive. GII genogroup was the main genogroup identified (83.0%; 83/100). About 42 (42.0%) samples were successfully sequenced and genotyped by RT‐PCR. Since one of the samples was dual infection, so we got 43 virus finally. Nine norovirus GII genotypes and four norovirus GI genotypes were detected in Huzhou during our research period. The main two norovirus GII genotypes were GII.2[P16] (54.8%; 23/43) and GII.17[P17] (11.9%; 5/43). We characterized the molecular epidemiology of norovirus infection in acute gastroenteritis patients during 2018. GII genogroup was the main genogroup identified. The dominance norovirus genotype circulating in the population of Huzhou was GII.2[P16] in 2018.
Rainfall estimation methods in the Brazilian semiarid region: 30‐year evaluation on a monthly scale
Authors: dos Santos Vitor Juste , Calijuri Maria Lúcia , Ribeiro Júnior José Ivo , de Assis Leonardo Campos
Published: June 2020

Studies about evaluations of different rainfall estimation methods are important as they are usually applied in works related to water resources availability, public supply, watering, animal water supply, hydroelectric power generation, drought episodes' evaluation, among others. Studies that cover the entire area of the Brazilian semiarid within this scope are still scarce. In this context, the objective of this paper was to evaluate seven rain estimation methods, from different approaches, with the aid of statistical analysis. The focus was on the long term, using 30 years of data in monthly scale, in order to verify the methods performance in estimating the spatiotemporal behaviour of rainfall compared to data measured in situ, coming from rainfall and meteorological stations. The evaluation process was based on the random selection of training and testing stations, with the first being used to interpolate rainfall data using different methods, and the latter used to evaluate this estimates with the aid of statistical analysis. Finally, the results were standardized, interpreted and discussed. Of all the estimation methods evaluated, CHIRPS obtained the best performance when compared to field stations data used as test. From the results obtained, there is evidence that the best performance is due to the incorporation of several distinct data sources derived from in situ stations, geostationary satellite infrared sensor estimates and physiographic predictors. This information is not fully present in other evaluated methods. The worst estimation performances were in the eastern side of the Brazilian semiarid, an area that receives moisture from the Atlantic Ocean and has significant topographic variations, due to the set of the complex relief mountains present in the northeast coast of Brazil.
Long term outcomes of total humeral replacement for oncological reconstructions: A single institution experience
Authors: Bernthal Nicholas M. , Upfill‐Brown Alexander , Burke Zachary D. C. , Greig Danielle , Hwang Richard , Crawford Brooke , Eckardt Jeffrey J.
Published: June 2020

Background

There is a paucity of data on long‐term survivorship and outcomes for total humerus replacements (THR) with only two series reporting 10‐year survival.

Patients and Methods

A review of 769 consecutive, prospectively collected endoprosthetic reconstructions for oncological diagnoses at a single‐center between 1980 and 2019 was performed. Patients with THRs were isolated and analyzed for outcomes, complications, and modes of failure.

Results

Eighteen patients with 20 THR implants were identified. The median follow‐up for surviving patients was 148 months (interquartile range [IQR] = 74‐194) and 60 months (IQR = 17‐155 months) for all patients. Two prostheses required revision for failure, both for symptomatic shoulder dislocation. There were three local recurrences. Revision‐free survival at 5, 10, and 15 years was 100%, 86% and 86%, respectively. There were no cases of ulnar component failure, radial nerve palsy, or periprosthetic infection.

Conclusions

THR prosthesis survivorship is comparable to the previous series, with a longer follow‐up than has previously been reported. Symptomatic shoulder instability was common (25%), and was the only cause of revision. Reverse total shoulder could be an important way to address this in the future. Local recurrence rates were high, as has been reported elsewhere for THR.
The COVID‐19 Airway Management Isolation Chamber (CAMIC) for Ears
Authors: Tolisano Anthony M. , Blood Timothy C. , Riley Charles A. , Ruhl Douglas S. , Hong Steven S.
Published: June 2020

View Video S1 Laryngoscope, 2020
Air–water gas exchange in lakes and reservoirs measured from a moving platform by underwater eddy covariance
Authors: Berg Peter , Pace Michael L. , Buelo Cal D.
Published: June 2020

Air–water exchange rates of gasses, such as O2, CO2, and CH4, are widely used in ecosystem studies of lakes and reservoirs, but their magnitudes are often difficult to assess. In this proof‐of‐concept study, we measured gas exchange by underwater eddy covariance in such lentic systems from a moving platform. We used an Acoustic Doppler Velocimeter and a fast‐responding O2‐temperature sensor mounted in the bow of a boat to measure water velocity, O2 concentration, and temperature below the air–water interface (~ 10 cm) while the boat was propelled at constant speed (~ 25 cm s−1) by an electric trolling motor. Fluxes of O2 and heat across the air–water interface and standard gas exchange coefficients, k600, were calculated for every 3 min of traveled distance (~ 45 m). All deployments were done under calm low‐wind conditions where empirical relationships for k600 are most uncertain. Deployment averages of k600 ranged from 0.070 to 0.39 m d−1 and were strongly correlated with both the heat flux and the water temperature. In one deployment, a > 20% variation in mean water column O2 concentration was measured along a 1 km long transect of a reservoir. Given the typical size of O2 concentration differences over the air–water interface that drive gas exchange, such lateral variations can, even at a near‐constant exchange coefficient, result in highly biased whole‐ecosystem fluxes if based on stationary single‐point O2 measurements. “Mobile” aquatic eddy covariance measurements enable quantification of gas exchange in lakes and reservoirs under true in situ conditions and with high temporal and spatial resolution.
An application of Harrison's system theory model to spark a rapid telehealth expansion in the time of COVID‐19
Authors: Touson Jonathan C. , Azad Namita , Depue Corinne , Crimmins Timothy , Long Rosalie
Published: June 2020

Introduction

In response to the COVID‐19 pandemic, health systems had to quickly adopt a process for enabling targeted and patient‐centered care delivery. This case study describes the utilization of Harrison's open‐systems model to create an approach for rapid adoption of existing telehealth technologies in a large scale academic medical center.

Methods

An internal group of organizational developers, was enlisted to enable this effort. Local networks were employed and organized into focus groups to rapidly assess and address barriers to adoption and informal interviews with executive leadership were conducted to align organizational goals. Interventions include rapid deployment of focused and data driven provider, staff and patient support bolstered by effective communication and resource management.

Results

There was an increase in the number of patient portal activation codes by 75% during the month of March. The number of activation codes generated expectedly decreased in April as many patients now had activated patient portals. The video visit volume as a result of provider self‐scheduling increased went from a baseline of 0 to over 600 clinical visits.

Discussion

Experienced organizational development programs can facilitate adoption of change. The faculty practice of CUIMC has years of experience with supporting wide scale operational change centered on technology. In this case, providing engaged networks with tailored content that is focused on the process and available technology promoted rapid adoption and optimization.

Conclusion

In the setting of profound external pressure, experience with the ability to focus on tailoring training and support to the culture of the organization helped to rapidly increase the availability and success of telehealth visits for a large scale academic medical center.
SHORT syndrome in two Chinese girls: A case report and review of the literature
Authors: Zhang Yanhong , Ji Baolan , Li Jinsheng , Li Yanying , Zhang Mei , Ban Bo
Published: June 2020

Background

SHORT syndrome is a rare inherited multisystem disease that includes characteristic facial features, growth retardation, and metabolic anomalies and is related to heterozygous mutations in the PIK3R1 gene. However, it is difficult to ascertain the relationship between the phenotype and the genotype quickly and efficiently.

Methods

We report two Chinese girls with SHORT syndrome who presented with growth retardation, dysmorphic features, insulin resistance, and diabetes. Comprehensive medical evaluations were collected, including anthropometric measurements, laboratory measurements, and imaging examinations. Whole exome and Sanger sequencing was performed to detect and confirm the underlying genetic mutations in these patients. We prescribed metformin for the patients.

Results

The patients both presented diabetes, insulin resistance, short stature, lipodystrophy, and characteristic facial dysmorphic features. A heterozygous mutation was detected in the PIK3R1 gene (c.1615_1617del) of Patient 1. The analysis of patient 2 revealed another PIK3R1 mutation (c.1945C>T). After family validation, neither their parents nor their brothers had similar clinical presentations or carried the same mutation.

Conclusion

We identified two de novo heterozygous mutations in PIK3R1 as the cause of SHORT syndrome in two Chinese girls. Additionally, in terms of diabetes control, metformin works well in the early treatment stage.
Tuning of fractional complex‐order direct current motor controller using frequency domain analysis
Authors: Zheng Min , Zhang Guangfeng , Huang Tao
Published: June 2020

For the speed control of direct current motor, a fractional complex‐order controller (FCOC) is proposed in this paper. The FCOC is an extension of the fractional‐order controller. It is known that fractional‐order controllers exhibit strong robustness to open‐loop gain variations. However, in actual situations, due to external interference, the phase angle and gain of the system may change at the same time. The FCOC proposed in this paper adds an additional parameter, which makes the system show strong robustness when the phase angle and gain change simultaneously. Existing methods for parameter tuning of FCOCs only consider the preset gain crossover frequency and the expected phase margin. This may not allow the system to exhibit good dynamic and stable performance. In this paper, based on the frequency domain analysis, the parameters of the FCOC are tuned by integrating the gain crossover frequency, cutoff frequency, phase margin, and amplitude margin. The optimal solution satisfying a set of constraint equations is obtained by optimization algorithm. Finally, the simulation results are compared with those of the fractional‐order controller and the integer‐order controller. At the same time, the robustness of the system under disturbance is analyzed. The results show that the complex fractional‐order control presented in this paper has better dynamic performance and robustness.
Neural field equations with neuron‐dependent Heaviside‐type activation function and spatial‐dependent delay
Authors: Burlakov Evgenii , Zhukovskiy Evgeny , Verkhlyutov Vitaly
Published: June 2020

We introduce a neural field equation with a neuron‐dependent Heaviside‐type activation function and spatial‐dependent delay. The basic object of the study is represented by a Volterra–Hammerstein integral equation involving a discontinuous nonlinearity with respect to the state variable that is both time and space dependent. We replace the discontinuous nonlinearity by its multivalued convexification and obtain the corresponding Volterra–Hammerstein integral inclusion. We investigate the solvability of this inclusion using the properties of upper semicontinuous multivalued mappings with convex closed values. Based on these results, we study the solvability of an initial‐prehistory problem for the former neural field equation with the Heaviside‐type activation function. The application of multivalued analysis techniques allowed us to avoid some restrictive assumptions standardly used in the investigations of the solutions to neural field equations involving Heaviside‐type activation functions.
Predicting the noise in hybrid (phase and attenuation) x‐ray images acquired with the edge illumination technique
Authors: Hagen Charlotte Klara , Roche i Morgó Oriol , Olivo Alessandro
Published: June 2020

Purpose

To analyze the noise performance of the edge illumination phase‐based x‐ray imaging technique when applying “single‐shot” phase retrieval. The latter consists in applying a sample‐specific low‐pass filter to the raw data, leading to “hybrid” images in which phase and attenuation contrast are merged with each other. The second objective is to compare the hybrid images with attenuation‐only images based on their respective signal‐to‐noise ratio (SNR).

Methods

Noise is propagated from the raw images into the retrieved hybrid images, yielding analytic expressions for the variances and noise power spectra of the latter. An expression for the relative SNR between hybrid and attenuation images is derived. A comparison with simulated data is performed. Experimental data are also shown and discussed in the context of the theory.

Results

The noise transfer into the retrieved hybrid images is strongly related to the setup and acquisition parameters, as well as the imaged sample itself. Consequently, the relative merit between hybrid and attenuation images also depends on these criteria. Generally, the hybrid approach tends to perform worse for highly attenuating samples, as the availability of phase contrast is outweighed by the loss of photons that is necessarily encountered in hybrid acquisitions. On the contrary, the hybrid approach can lead to a much better SNR for weakly attenuating samples, as here phase effects lead to much stronger contrast, outweighing the reduction in photon numbers.

Conclusions

The analytic expressions inform the design of edge illumination setups that lead to minimum noise transfer into the retrieved hybrid images. We also anticipate our theory to guide the decision as to which imaging mode (hybrid or attenuation) to use in order to maximize SNR for a specific sample.
Non‐water‐excitation MR spectroscopy techniques to explore exchanging protons in human brain at 3 T
Authors: Dziadosz Martyna , Bogner Wolfgang , Kreis Roland
Published: June 2020

Purpose

To develop localization sequences for in vivo MR spectroscopy (MRS) on clinical scanners of 3 T to record spectra that are not influenced by magnetization transfer from water.

Methods

Image‐selected in vivo spectroscopy (ISIS) localization and chemical‐shift‐selective excitation (termed I‐CSE) was combined in two ways: first, full ISIS localization plus a frequency‐selective spin‐echo and second, two‐dimensional (2D) ISIS plus a frequency‐selective excitation and slice‐selective refocusing. The techniques were evaluated at 3 T in phantoms and human subjects in comparison to standard techniques with water presaturation or metabolite‐cycling. ISIS included gradient‐modulated offset‐independent adiabatic (GOIA)‐type adiabatic inversion pulses; echo times were 8‐10 ms.

Results

The novel 2D and 3D I‐CSE methods yield upfield spectra that are comparable to those from standard MRS, except for shorter echo times and a limited frequency range. On the downfield/high‐frequency side, they yield much more signal for exchangeable protons when compared to MRS with water presaturation or metabolite‐cycling and longer echo times.

Conclusion

Novel non‐water‐excitation MRS sequences offer substantial benefits for the detection of metabolite signals that are otherwise suppressed by saturation transfer from water. Avoiding water saturation and using very short echo times allows direct observation of faster exchanging moieties than was previously possible at 3 T and additionally makes the methods less susceptible to fast T2 relaxation.
Fast chemical exchange saturation transfer imaging based on PROPELLER acquisition and deep neural network reconstruction
Authors: Guo Chenlu , Wu Jian , Rosenberg Jens T. , Roussel Tangi , Cai Shuhui , Cai Congbo
Published: June 2020

Purpose

To develop a method for fast chemical exchange saturation transfer (CEST) imaging.

Methods

The periodically rotated overlapping parallel lines enhanced reconstruction (PROPELLER) sampling scheme was introduced to shorten the acquisition time. Deep neural network was employed to reconstruct CEST contrast images. Numerical simulation and experiments on a creatine phantom, hen egg, and in vivo tumor rat brain were performed to test the feasibility of this method.

Results

The results from numerical simulation and experiments show that there is no significant difference between reference images and CEST‐PROPELLER reconstructed images under an acceleration factor of 8.

Conclusion

Although the deep neural network is trained entirely on synthesized data, it works well on reconstructing experimental data. The proof of concept study demonstrates that the combination of the PROPELLER sampling scheme and the deep neural network enables considerable acceleration of saturated image acquisition and may find applications in CEST MRI.
A hybrid stochastic river environmental restoration modeling with discrete and costly observations
Authors: Yoshioka Hidekazu , Tsujimura Motoh , Hamagami Kunihiko , Yoshioka Yumi
Published: June 2020

A recent river environmental restoration problem is approached from a standpoint of stochastic control of hybrid regime‐switching diffusion processes with discrete and costly observations. This setting harmonizes with real problems because continuously obtaining environmental and ecological information is difficult, and is often costly. The main problem is to decide when and how much of the sediment should be supplied into a river environment to effectively suppress bloom of benthic algae. The interventions are allowed only at observation times. Finding the optimal river restoration policy ultimately reduces to solving an optimality equation in an unconventional form due to the observation cost and discrete observations. We show its unique solvability and present a connection with degenerate parabolic partial differential equations, with which we can construct an effective algorithm for its approximation. An uncertainty‐averse optimization problem is also considered as an advanced problem. Coefficients and parameter values are identified from experimental and observation results to numerically compute the optimal restoration policy of an existing river environment with and without uncertainty.
Gifted underachievement within a self‐regulated learning framework: Proposing a task‐dependent model to guide early identification and intervention
Authors: Ridgley Lisa M. , DaVia Rubenstein Lisa , Callan Gregory L.
Published: June 2020

Current theoretical and operational definitions of underachievement require that students show sustained suppressed academic achievement. Yet, early detection may allow for effective intervention before underachievement becomes a chronic issue. While existing identification procedures were not designed to detect underachievement before low academic performance occurs, the integration of self‐regulated learning (SRL) into these practices may promote earlier identification and intervention. This conceptual paper (a) anchors gifted underachievement within Zimmerman's SRL model, (b) examines existing gifted literature investigating SRL components to demonstrate the benefits of applying an SRL model, and (c) proposes a comprehensive measurement and intervention technique to capture important motivational variables at the task level. By measuring SRL processes and underachievement at a task‐specific level, we can target interventions to specific needs, address underachievement before it becomes a persistent problem, and help learners reach their academic potential.
Angiotensin‐converting enzyme 2: The old door for new severe acute respiratory syndrome coronavirus 2 infection
Authors: Tan Heng Wee , Xu Yan‐Ming , Lau Andy T. Y.
Published: June 2020

Coronavirus (CoV) disease 2019 (COVID‐19) is an ongoing pandemic caused by severe acute respiratory syndrome CoV 2 (SARS‐CoV‐2). The highly contagious SARS‐CoV‐2 belongs to the genus Betacoronavirus, and it is phylogenetically closely related to SARS‐CoV, a human CoV that caused an outbreak back in 2002 to 2003. Both SARS‐CoV‐2 and SARS‐CoV enter human cells via the interactions between viral crown‐like spike protein and human angiotensin‐converting enzyme 2 (ACE2) receptor. Here, we aim to review the involvement of ACE2 in human CoV infections by discussing the roles of ACE2 in CoV evolution, cross‐species transmissibility, and COVID‐19 susceptibility. We also provide our perspectives on COVID‐19 treatment and prevention.
Conjunctival reconstruction via enrichment of human conjunctival epithelial stem cells by p75 through the NGF-p75-SALL2 signaling axis
Authors: Wu Nianxuan , Yan Chenxi , Chen Junzhao , Yao Qinke , Lu Yang , Yu Fei , Sun Hao , Fu Yao
Published: June 2020

Severe conjunctival diseases can cause significant conjunctival scarring, which seriously limits eye movement and affects patients’ vision. Conjunctival reconstruction remains challenging due to the lack of efficient methods for stem cells enrichment. This study indicated that p75 positive conjunctival epithelial cells (CjECs) were mainly located in the basal layer of human conjunctival epithelium and showed an immature differentiation state in vivo. The p75 strongly positive (p75++) CjECs enriched by immuno-magnetic beads exhibited high expression of stem cell markers and low expression of differentiated keratins. During continuous cell passage cultivation, p75++ CjECs showed the strongest proliferation potential and were able to reconstruct the conjunctiva in vivo with the most complete structure and function. Exogenous addition of NGF promoted the differentiation of CjECs by increasing nuclear localization of SALL2 in p75++ CjECs while proNGF played an opposite role. Altogether, p75++ CjECs present stem cell characteristics and exhibit the strongest proliferation potential so can be used as seed cells for conjunctival reconstruction, and NGF-p75-SALL2 signaling pathway was involved in regulating the differentiation of CjECs.
Grafted human pluripotent stem cell-derived cortical neurons integrate into adult human cortical neural circuitry
Authors: Grønning Hansen Marita , Laterza Cecilia , Palma-Tortosa Sara , Kvist Giedre , Monni Emanuela , Tsupykov Oleg , Tornero Daniel , Uoshima Naomi , Soriano Jordi , Bengzon Johan , Martino Gianvito , Skibo Galyna , Lindvall Olle , Kokaia Zaal
Published: June 2020

Several neurodegenerative diseases cause loss of cortical neurons, leading to sensory, motor, and cognitive impairments. Studies in different animal models have raised the possibility that transplantation of human cortical neuronal progenitors, generated from pluripotent stem cells, might be developed into a novel therapeutic strategy for disorders affecting cerebral cortex. For example, we have shown that human long-term neuroepithelial-like stem (lt-NES) cell-derived cortical neurons, produced from induced pluripotent stem cells and transplanted into stroke-injured adult rat cortex, improve neurological deficits and establish both afferent and efferent morphological and functional connections with host cortical neurons. So far, all studies with human pluripotent stem cell-derived neurons have been carried out using xenotransplantation in animal models. Whether these neurons can integrate also into adult human brain circuitry is unknown. Here, we show that cortically fated lt-NES cells, which are able to form functional synaptic networks in cell culture, differentiate to mature, layer-specific cortical neurons when transplanted ex vivo onto organotypic cultures of adult human cortex. The grafted neurons are functional and establish both afferent and efferent synapses with adult human cortical neurons in the slices as evidenced by immuno-electron microscopy, rabies virus retrograde monosynaptic tracing, and whole-cell patch-clamp recordings. Our findings provide the first evidence that pluripotent stem cell-derived neurons can integrate into adult host neural networks also in a human-to-human grafting situation, thereby supporting their potential future clinical use to promote recovery by neuronal replacement in the patient’s diseased brain.
A microfoundational model of real options reasoning: The roles of individual search propensity and perceived uncertainty
Authors: Zhang Stephen X. , Gao Renfei , Odeh Nicolás , Leatherbee Michael
Published: June 2020

Research Summary

To explain heterogeneity in real options reasoning (ROR) across entrepreneurial ventures, we propose a microfoundational model to explore the relationships between a firm leader's search propensity, perceived uncertainty and the firm‐level ROR‐based behaviors. Using a panel survey of 134 founder‐CEOs of new ventures, we find that founder‐CEOs' search propensity is positively related to ROR‐based behaviors in their ventures. Moreover, we find that founder‐CEOs' perceived effect uncertainty is positively related to the ROR‐based behaviors, but perceived response uncertainty is negatively related to the ROR‐based behaviors, revealing the importance of considering distinct types of uncertainty in entrepreneurs' ROR. Our microfoundational model advances the ROR literature by delineating how individual‐level factors may drive ROR in firms that face uncertainty.

Managerial Summary

Flexibility is key to startup success. However, entrepreneurs craft and embed flexibility to different degrees and under different situations. In order to explain this heterogeneity, we study the roles of entrepreneurs' individual characteristics. Particularly, we study search propensity and perceived uncertainty (distinguishing among different types) in relation to flexibility, formally known as real options reasoning (ROR). Analysis of 134 founder‐CEOs of new ventures in Start‐Up Chile showed that founder‐CEOs' search propensity is positively related to ROR in their ventures. Moreover, founder‐CEOs' perceived uncertainty is related to ROR in ways that depend on the type of uncertainty the entrepreneurs perceive; thus, not all types of uncertainties relate positively to ROR. Such findings carry managerial implications to those who want to understand why certain startups are more flexible.
Effect of atomization on surface oxide composition in 316L stainless steel powders for additive manufacturing
Authors: Riabov Dmitri , Hryha Eduard , Rashidi Masoud , Bengtsson Sven , Nyborg Lars
Published: June 2020

The initial oxide state of powder is essential to the robust additive manufacturing of metal components using powder bed fusion processes. However, the variation of the powder surface oxide composition as a function of the atomizing medium is not clear. This work summarizes a detailed surface characterization of three 316L powders, produced using water atomization (WA), vacuum melting inert gas atomization (VIGA), and nitrogen atomization (GA). X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy analyses were combined to characterize the surface state of the powders. The results showed that the surface oxides consisted of a thin (~4 nm) iron oxide (Fe2O3) layer with particulate oxide phases rich in Cr, Mn, and Si, with a varying composition. XPS analysis combined with depth‐profiling showed that the VIGA powder had the lowest surface coverage of particulate compounds, followed by the GA powder, whereas the WA powder had the largest fraction of particulate surface oxides. The composition of the oxides was evaluated based on the XPS analysis of the oxide standards. Effects of Ar sputtering on the peak positions of the oxide standards were evaluated with the aim of providing an accurate analysis of the oxide characteristics at different etch depths.
Conformation‐Tuning Effect of Asymmetric Small Molecule Acceptors on Molecular Packing, Interaction, and Photovoltaic Performance
Authors: Luo Zhenghui , Ma Ruijie , Xiao Yiqun , Liu Tao , Sun Huiliang , Su Mengyao , Guo Qing , Li Guanghao , Gao Wei , Chen Yuzhong , Zou Yang , Guo Xugang , Zhang Maojie , Lu Xinhui , Yan He , Yang Chuluo
Published: June 2020

Understanding the conformation effect on molecular packing, miscibility, and photovoltaic performance is important to open a new avenue for small‐molecule acceptor (SMA) design. Herein, two novel acceptor–(donor‐acceptor1‐donor)–acceptor (A‐DA1D‐A)‐type asymmetric SMAs are developed, namely C‐shaped BDTP‐4F and S‐shaped BTDTP‐4F. The BDTP‐4F‐based polymer solar cells (PSCs) with PM6 as donor, yields a power conversion efficiency (PCE) of 15.24%, significantly higher than that of the BTDTP‐4F‐based device (13.12%). The better PCE for BDTP‐4F‐based device is mainly attributed to more balanced charge transport, weaker bimolecular recombination, and more favorable morphology. Additionally, two traditional A‐D‐A‐type SMAs (IDTP‐4F and IDTTP‐4F) are also synthesized to investigate the conformation effect on morphology and device performance. Different from the device result above, here, IDTP‐4F with S‐shape conformation outperforms than IDTTP‐4F with C‐shape conformation. Importantly, it is found that for these two different types of SMA, the better performing binary blend has similar morphological characteristics. Specifically, both PM6:BDTP‐4F and PM6:IDTP‐4F blend exhibit perfect nanofibril network structure with proper domain size, obvious face‐on orientation and enhance donor‐acceptor interactions, thereby better device performance. This work indicates tuning molecular conformation plays pivotal role in morphology and device effciciency, shining a light on the molecular design of the SMAs.