sensitivity threshold
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2022 ◽  
Vol 15 ◽  
Author(s):  
Anthony Beh ◽  
Paul V. McGraw ◽  
Ben S. Webb ◽  
Denis Schluppeck

Loss of vision across large parts of the visual field is a common and devastating complication of cerebral strokes. In the clinic, this loss is quantified by measuring the sensitivity threshold across the field of vision using static perimetry. These methods rely on the ability of the patient to report the presence of lights in particular locations. While perimetry provides important information about the intactness of the visual field, the approach has some shortcomings. For example, it cannot distinguish where in the visual pathway the key processing deficit is located. In contrast, brain imaging can provide important information about anatomy, connectivity, and function of the visual pathway following stroke. In particular, functional magnetic resonance imaging (fMRI) and analysis of population receptive fields (pRF) can reveal mismatches between clinical perimetry and maps of cortical areas that still respond to visual stimuli after stroke. Here, we demonstrate how information from different brain imaging modalities—visual field maps derived from fMRI, lesion definitions from anatomical scans, and white matter tracts from diffusion weighted MRI data—provides a more complete picture of vision loss. For any given location in the visual field, the combination of anatomical and functional information can help identify whether vision loss is due to absence of gray matter tissue or likely due to white matter disconnection from other cortical areas. We present a combined imaging acquisition and visual stimulus protocol, together with a description of the analysis methodology, and apply it to datasets from four stroke survivors with homonymous field loss (two with hemianopia, two with quadrantanopia). For researchers trying to understand recovery of vision after stroke and clinicians seeking to stratify patients into different treatment pathways, this approach combines multiple, convergent sources of data to characterize the extent of the stroke damage. We show that such an approach gives a more comprehensive measure of residual visual capacity—in two particular respects: which locations in the visual field should be targeted and what kind of visual attributes are most suited for rehabilitation.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Kolten Kersey ◽  
Andrew Gonzalez

Background and Objective:  As technology is integrated further into medicine, more specialties are discovering new uses for it in their clinical practice. However, the tasks that we want technology to complete are often removed from developer’s intended tasks.  A field of research is growing that integrates medicine with current AI technology to bridge the gap and utilize already existing technology for medical uses.  We desire to use an active learning pipeline (a form of machine learning) to automate the labeling of blood vessels on angiograms and potentially develop the ability to detect occlusions. By using machine learning, it would essentially allow the machine to teach itself with human guidance.      Methods:  A machine learning pipeline is in development for automation of the process.  To create a baseline for the machine to start learning, the first set of angiograms are being labeled by hand using the program 3D Slicer.  For the first pass, we have been quickly labeling the blood vessels by changing the color sensitivity threshold to highlight the darker blood vessels juxtaposed next to lighter tissue.  For the second pass, we have erased any erroneous highlighting that was picked up in the first pass such as tools, tissue, contrast outside the injection site, and sutures.  For the third pass, we have labeled and segmented the arteries into specific vessels such as femoral, common iliac, internal iliac, etc. This will then be entered into the machine for automated learning.    Results:  We are in the process of labeling the initial image set.      Potential Impact:   By creating a lab for angiogram automation, it will allow physicians to efficiently search images for specific arteries and save valuable time usually spent searching images.  This would also allow for automated labeling of occlusions that a physician could then look at to verify.     


2021 ◽  
Author(s):  
Nicholas J. Santistevan ◽  
Jessica C. Nelson ◽  
Elelbin A. Ortiz ◽  
Andrew H. Miller ◽  
Dima Kenj Halabi ◽  
...  

AbstractThe ability to filter sensory information into relevant versus irrelevant stimuli is a fundamental, conserved property of the central nervous system and is accomplished in part through habituation learning. Synaptic plasticity that underlies habituation learning has been described at the cellular level, yet the genetic regulators of this plasticity remain poorly understood, as do circuits that mediate sensory filtering. A forward genetic screen for zebrafish genes that control habituation learning identified a mutant allele doryp177 that caused reduced habituation of the acoustic startle response. Whole-genome sequencing identified the calcium voltage-gated channel auxiliary subunit alpha-2/delta-3 (cacna2d3) as a candidate gene affected in doryp177 mutants. Behavioral characterization of larvae homozygous for two additional, independently derived mutant alleles of cacna2d3, together with failure of these alleles to complement doryp177, confirmed a critical role for cacna2d3 in habituation learning. Notably, detailed analyses of the acoustic response in mutant larvae also revealed increased startle sensitivity to acoustic stimuli, suggesting a broader role for cacna2d3 in controlling innate response thresholds to acoustic stimuli. Taken together, our data demonstrate a critical role for cacna2d3 in sensory filtering, a process that is disrupted in human CNS disorders, e.g. ADHD, schizophrenia, and autism.


2021 ◽  
Vol 923 (1) ◽  
pp. 2 ◽  
Author(s):  
A. Josephy ◽  
P. Chawla ◽  
A. P. Curtin ◽  
V. M. Kaspi ◽  
M. Bhardwaj ◽  
...  

Abstract We investigate whether the sky rate of fast radio bursts (FRBs) depends on Galactic latitude using the first catalog of FRBs detected by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Project. We first select CHIME/FRB events above a specified sensitivity threshold in consideration of the radiometer equation, and then we compare these detections with the expected cumulative time-weighted exposure using Anderson–Darling and Kolmogorov–Smirnov tests. These tests are consistent with the null hypothesis that FRBs are distributed without Galactic latitude dependence (p-values distributed from 0.05 to 0.99, depending on completeness threshold). Additionally, we compare rates in intermediate latitudes (∣b∣ < 15°) with high latitudes using a Bayesian framework, treating the question as a biased coin-flipping experiment–again for a range of completeness thresholds. In these tests the isotropic model is significantly favored (Bayes factors ranging from 3.3 to 14.2). Our results are consistent with FRBs originating from an isotropic population of extragalactic sources.


Author(s):  
Jean Paul N’Guessan ◽  
Songuigama Coulibaly ◽  
Abdulrahim A. Alzain ◽  
Drissa Sissouma ◽  
William Yavo ◽  
...  

Background: To overcome drug resistance to current antimalarial drugs, we propose the synthesis and in vitro evaluation of the antiplasmodial activity of a series of 5-chlorobenzimidazolyl-chalcones against chloroquino sensitive (CQ-S) and chloroquino resistant (CQ-R) strains of P. falciparum. Objective: This study aimed to establish through structure-activity relationship studies and docking, the structural elements essential for antiplasmodial activities. Methods: The antiplasmodial activity of these benzimidazolylchalcones was carried out according to the Rieckmann microtest technique, followed by the determination of the concentrations inhibiting 50% of the production of parasitic HRP2 antigens (IC50) by ELISA. Chloroquine was used as a reference molecule with a sensitivity threshold set at 100 µM. Molecular docking was performed using sensitive (PDB ID: 1J3I) and resistant (PDB ID: 4DP3) dihydrofolate reductase-thymidylate synthase proteins (PfDHFR-TS). Results: All benzimidazolylchalcones tested expressed antiplasmodial activities especially against chloroquine resistant isolates (IC50 = 0.32-44.38 µM). The best profile against both isolates was the methoxylated derivative (3e) with an IC50 ranging from 0.32 to 1.96 µM. This compound had the best antimalarial activity against CQ-S isolates. On CQ-R isolates, the unsubstituted 5-chlorobenzimidazole derivative (3b) had exalted activity (IC50 = 0.78 µM).  We selected a weakly active non-chlorinated derivative 3a and chlorinated derivatives 3b, 3d, 3e and 3f) with IC50< 3µM against the chloroquine-resistant strain to perform docking studies. These revealed that the pyrrolic nitrogen of benzimidazole and the ketone of propenone are the main chemical entities involved in the interaction at the receptor. Moreover, ADMET studies showed favorable pharmacokinetic properties. Conclusion: Molecular docking studies confirmed the experimental findings and revealed the possible interactions pattern. Derivatives 3b and 3e, which showed promising binding affinities against PfDHFR-TS, can be proposed as lead compounds for the development of antimalarial drug candidates.


Motor Control ◽  
2021 ◽  
Vol 25 (4) ◽  
pp. 616-630
Author(s):  
Xiu Hu ◽  
Shaojun Lyu ◽  
Min Mao ◽  
Jianwei Zhang ◽  
Wei Sun ◽  
...  

The team developed the newly compiled eight methods and five steps of Tai Chi (EMFSTC), which includes introductory routines to Tai Chi characterized by simple structures. This study examined the effectiveness of EMFSTC practice on balance control. A total of 31 participants were randomly assigned to EMFSTC (n = 15, age = 66.4 ± 1.7 years, received 16-week EMFSTC practice) or control (n = 16, age = 66.7 ± 1.8 years, received no practice) groups. Significant group by training interactions were observed. After EMFSTC practice, balance control improved, as indicated by decreased root mean square and mean velocity of center of pressure, proprioception threshold during knee extension, and plantar tactile sensitivity threshold at the arch. EMFSCT can be an effective rehabilitation modality to improve balance control among older adults.


2021 ◽  
Author(s):  
anis charrada ◽  
Abdelaziz Samet

Abstract A robust and sparse Twin Support Vector Regression based on Dual Tree Discrete Wavelet Transform algorithm is conceived in this paper and applied to 28, 38, 60 and 73-GHz LOS (Line-of-Sight) wireless multipath transmission system in 5G Indoor Hotspot (InH) settings (simple, semi-complex and complex conference rooms) under small receiver sensitivity threshold. The algorithm establishes a denoising process in the learning phase based on Dual Tree Discrete Wavelet Transform (DT-CWT) which is suitable for time-series data. Additionally, the Close-In (CI) free space reference distance path loss model is analyzed and the large-scale propagation and probability distribution functions are investigated by determining the PLE (Path Loss Exponent) and the standard deviation of Shadow Factor (SF) for each InH scenario under consideration. Performance are evaluated under twelve (12) configuration scenarios, according to three criteria: mobility (0/3mps), receiver sensitivity threshold (-80/-120 dBm) and type of the InH area (simple, semi-complex and complex conference room). Experimental results confirm the effectiveness of the proposed approach compared to other standard techniques.


2021 ◽  
Author(s):  
Olga V. Morozova ◽  
Dmitry V. Klinov

Nanosilver (in a range 1–100 nm) binds with thyol-, amino- and carboxy-groups of aminoacid residues of proteins and nucleic acids, thus providing inactivation of pathogenic multidrug-resistant microorganisms. Besides antibacterial, antiviral, antifungal and anti-cancer properties Ag-based nanomaterials possess anti-inflammatory, anti-angiogenesis and antiplatelet features. Drug efficacy depends on their stability, toxicity and host immune response. Citrate coated Ag nanoparticles (NPs) remain stable colloid solutions in deionized water but not in the presence of ions due to replacement of Ag+ by electrolyte ions, potential formation of insoluble AgCl, subsequent catalyzed oxidative corrosion of Ag and further dissolution of surface layer of Ag2O. Protein shells protect core of AgNPs from oxidation, dissolution, aggregation and provide specific interactions with ligands. These nanoconjugates can be used for immunoassays and diagnostics but the sensitivity threshold does not exceed 10 pg Cytotoxicity of AgNPs conjugated with proteins is associated with the rate of intracellular Ag+ release, a ‘Trojan horse’ effect, and exceeds one of Ag+ because of endocytosis uptake of NPs but not ions. Relatively toxic nanosilver causes immunosuppression of the majority of cytokines with a few exceptions (IL-1β, G-CSF, MCP-1) whereas AgNO3 additionally activate TNFα and IL8 gene expression.


2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
А.А. Potapov ◽  

The estimation method for signal-to-noise ratio threshold values pertinent for low-level signals detection is developed and employed. The method is applicable for original energy detection technique based upon distribution-free statistics computed using spectrum samples provided by measuring equipment. Estimated thresholds are determined by measuring equipment inherent noise fluctuations and can be established in advance for certain hardware settings and sample lengths. For a typical spectrum analyzer model estimated sensitivity threshold varied from +0,6 dB to –11 dB for spectrum samples lengths ranged between 470 and 30 000 spectrums respectively. Experimental data confirmed estimated values and equivalence of sensitivity thresholds for white noise (generated by analog generator) and broadcasted LTE signals (generated by cellular base stations). The suggested energy detection technique is independent of signal's modulation, signal's probability distribution features, and intermittent or sporadic signal's total duration allotment profile within data acquisition period.


2021 ◽  
Vol 49 (4) ◽  
pp. 1547-1554
Author(s):  
Laura E. Kilpatrick ◽  
Stephen J. Hill

It has become increasingly apparent that some G protein-coupled receptors (GPCRs) are not homogeneously expressed within the plasma membrane but may instead be organised within distinct signalling microdomains. These microdomains localise GPCRs in close proximity with other membrane proteins and intracellular signalling partners and could have profound implications for the spatial and temporal control of downstream signalling. In order to probe the molecular mechanisms that govern GPCR pharmacology within these domains, fluorescence techniques with effective single receptor sensitivity are required. Of these, fluorescence correlation spectroscopy (FCS) is a technique that meets this sensitivity threshold. This short review will provide an update of the recent uses of FCS based techniques in conjunction with GPCR subtype selective fluorescent ligands to characterise dynamic ligand–receptor interactions in whole cells and using purified GPCRs.


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