scholarly journals Distinctions among real and apparent respiratory motions in human fMRI data

2019 ◽  
Author(s):  
Jonathan D. Power ◽  
Benjamin M. Silver ◽  
Marc J. Dubin ◽  
Alex Martin ◽  
Rebecca M. Jones
Keyword(s):  
Respiratory Motion ◽  
Low Frequency ◽  
Vertical Position ◽  
List Type ◽  
Tissue Mass ◽  
Real Motion ◽  
Good Concordance ◽  
Image Quality Measures ◽  
Anterior Posterior ◽  
Phase Encode

AbstractHead motion estimates in functional magnetic resonance imaging (fMRI) scans appear qualitatively different with sub-second image sampling rates compared to the multi-second sampling rates common in the past. Whereas formerly the head appeared still for much of a scan with brief excursions from baseline, the head now appears to be in constant motion, and motion estimates often seem to divulge little information about what is happening in a scan. This constant motion has been attributed to respiratory oscillations that do not alias at faster sampling rates, and investigators are divided on the extent to which such motion is “real” motion or only “apparent” pseudomotion. Some investigators have abandoned the use of motion estimates entirely due to these considerations. Here we investigate the properties of motion in several fMRI datasets sampled at rates between 720-1160 ms, and describe 5 distinct kinds of respiratory motion: 1) constant real respiratory motion in the form of head nodding most evident in vertical position and pitch, which can be very large; 2) constant pseudomotion at the same respiratory rate as real motion, occurring only in the phase encode direction; 3) punctate real motions occurring at times of very deep breaths; 4) a low-frequency pseudomotion in only the phase encode direction following very deep breaths; 5) slow modulation of vertical and anterior-posterior head position by the respiratory envelope. We reformulate motion estimates in light of these considerations and obtain good concordance between motion estimates, physiologic records, image quality measures, and events evident in the fMRI signals.Highlights- Examines several fast-TR datasets with sampling rates of 720-1160 ms- Identifies 7 kinds of motion in fMRI scans, 5 of them related to respiration- Identifies 2 forms of pseudomotion occurring only in phase encode direction- Pseudomotion is a function of soft tissue mass, not lung volume- Reformulates motion estimates to draw out particular kinds of motion

MO663THE UTILITY OF SMART SCALES TO MONITOR BODY COMPOSITION IN HEMODIALYSIS PATIENTS

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Lucia Cordero ◽  
Marta Rivero Martínez ◽  
Paula Jara Caro Espada ◽  
Elena Gutiérrez ◽  
Evangelina Mérida ◽  
...  
Keyword(s):  
Body Composition ◽  
Fat Tissue ◽  
Lean Tissue ◽  
Tissue Mass ◽  
Composition Data ◽  
The Mean ◽  
Good Concordance ◽  
Urea Distribution Volume ◽  
Assess Body Composition

Abstract Background and Aims Overhydration (OH) is an independent predictor of mortality on hemodialysis (HD). The gold standard to assess OH is BCM monitor from Fresenius®, however BCM is a hospital hold device limiting its use. New smart scales have emerged as household devices reporting daily body composition data. Objective To determine if Renpho ES-CS20M® could be useful on a 52 HD patient to estimate body composition data. Method 72 body composition assessments (BCA) during mid-week HD session were performed. Each BCA included: (1) Predialysis Renpho measurement, (2) Predialysis BCM monitor measurement, (3) Postdialysis Renpho measurement. To track the fluid balance during the HD session: (1) we recorded ultrafiltration, (2) food or fluid intake was not allowed, and (3) none of the HD patients urinated during the HD session. If any intravenous fluids were needed during the HD session, we subtracted them off from UF. Results Data from 52 HD patients were studied (age 58.8 ± 16.8 years, 56.9 % males, 14.7% diabetics), with a mean pre-HD weight of 70.0 ± 13. 4 Kg, overhydration of 1.7 ± 1.5 L and urea distribution volume of 31.7 ± 5.7 L. The mean ultrafiltration during HD session was -1.8 ± 0.9 L. Renpho estimated a Pre – HD hydration of 34.25 ± 6.02 Kg vs 33.4 ± 5.7 Kg by BCM, showing a good concordance between methods (ICC 0.788 [0.67-0.86], B -0.58, p <0.01). Renpho poorly estimated pre – HD lean tissue mass at 45.4 ± 6.9 Kg compared with 33.8 ± 8.0 Kg by BCM. Although Renpho was able to provide a moderate concordant estimation of fat tissue mass (33.8 ± 8.0 % with Renpho vs 34.7 ± 9.6%), the bias proportion was unacceptable. Post- HD hydration by Renpho was not able to reproduce the ultrafiltracion achieved during the HD session (pre-HD 34.25 ± 6.02 Kg vs post-HD 34.08 ± 6.00 Kg). Conclusion Renpho has a proportional bias estimating predialysis hydration compared with BCM monitor, but is not able to assess changes produced with ultrafiltration or other parameters of body composition (as lean or fat tissue mass). Although smart scales are unacurate to assess body composition on HD patients, they could be useful on the follow up of them changing the accuracy for frequency.

scholarly journals The Tangential Force Affecting the Radial Baffles in a Stirred Vessel: Analysis of the Macro-instability Related Component

10.14311/450 ◽  
2003 ◽  
Vol 43 (4) ◽  
Author(s):  
P. Hasal ◽  
I. Fořt ◽  
J. Kratěna
Keyword(s):  
Experimental Data ◽  
Spectral Analysis ◽  
Tangential Force ◽  
Low Frequency ◽  
Frequency Component ◽  
Relative Magnitude ◽  
Tangential Component ◽  
Vertical Position ◽  
Total Force ◽  
Rushton Turbine

Experimental data obtained by measuring the tangential component of the force affecting radial baffles in a flat-bottomed cylindrical mixing vessel stirred with a Rushton turbine impeller is analysed. Spectral analysis of the experimental data demonstrated the presence of its macro-instability (MI) related low-frequency component embedded in the total force. Two distinct dimensionless frequencies (both directly proportional to the impeller speed of rotation N) of the occurence of the MI component were detected: a lower frequency of approximately 0.025N and a higher frequency of about 0.085N. The relative magnitude QMI of the MI-related component of the total tangential force was evaluated by a combination of proper orthogonal decomposition (POD) and spectral analysis. The values of magnitude QMI varied in the interval [rom approximately 0.05 to 0.30. The magnitude QMI takes maximum values at low Reynolds number values (in laminar and transitional regions). In the turbulent region (ReM >20000) the QMI value is low and practically constant. The dependence oj the QMI values on vertical position in the vessel is only marginal. The results suggest that the magnitude of the MI component of the force is significantly influenced by the liquid viscosity and density.

scholarly journals Electromechanical coupling dynamic modeling and analysis of vertical electrodynamic shaker considering low frequency lateral vibration

2020 ◽  
Vol 12 (10) ◽  
pp. 168781402096385
Author(s):  
Shuguang Zuo ◽  
Zhaoyang Feng ◽  
Jian Pan ◽  
Xudong Wu
Keyword(s):  
Dynamic Model ◽  
Electromechanical Coupling ◽  
Low Frequency ◽  
Coupling Model ◽  
Vertical Position ◽  
Force Model ◽  
Lateral Vibration ◽  
Modeling And Analysis ◽  
Electrodynamic Shaker ◽  
Coupling Dynamic

For the problem of relatively severe lateral vibration found in the vertical electrodynamic shaker experiment, an electromechanical coupling dynamic model of the electrodynamic shaker considering low-frequency lateral vibration is proposed. The reason and mechanism of the lateral vibration is explained and analyzed through this model. To establish this model, an electromagnetic force model of overall conditions is firstly built by fitting force samples with neural network method. The force samples are obtained by orthogonal test of finite element simulation, in which five factors of the moving coil including current, vertical position, flipping eccentricity angle, radial translational eccentric direction and distance are considered. Secondly, a 7-dof dynamic model of the electrodynamic shaker is developed with the consideration of the lateral vibration of the moving system. To obtain the transfer function accurately, the stiffness and damping parameters are identified. Finally, an electromechanical dynamic model is established by coupling the force model and the 7-dof dynamic model, and it is verified by experiments. The coupling model proposed can be further used for the control and optimization of the electrodynamic shaker.

Head-Trunk Coordination During Linear Anterior-Posterior Translations

2003 ◽  
Vol 89 (4) ◽  
pp. 1891-1901 ◽  
Author(s):  
Emily A. Keshner
Keyword(s):  
Vestibular System ◽  
Healthy Subjects ◽  
Low Frequency ◽  
Head Acceleration ◽  
Response Latencies ◽  
Distraction Task ◽  
Analysis System ◽  
Post Hoc ◽  
Linear Accelerometer ◽  
Anterior Posterior

The purpose of this study was to evaluate the relative contributions of inputs from the vestibular system and the trunk to head-trunk coordination. Twelve healthy adults and 6 adults with diminished bilateral labyrinthine input (LD) were seated with their trunk either fixed to the seat or free to move. Subjects received 10-cm, 445-cm/s2 anterior-posterior ramps and 0.35- to 4.05-Hz sum-of-sines translations while performing a mental distraction task in the dark. Kinematics of the head and trunk were derived from an Optotrak motion analysis system and a linear accelerometer placed on the head. EMG signals were collected from neck and paraspinal muscles. Data were tested for significance with multivariate ANOVA (MANOVA) and Bonferroni post hoc analyses. Initial linear and angular head acceleration directions differed in healthy subjects when the trunk was fixed or free, but did not differ in LD subjects. Peak head angular accelerations were significantly greater with the trunk fixed than when free, and were greater in LD than in control subjects. EMG response latencies did not differ when the trunk was fixed or free. Low-frequency phase responses in the healthy subjects were close to 90° and had a delayed descent as frequency increased, suggesting some neural compensation that was absent in the LD subjects. Results of this study revealed a strong initial reliance on system mechanics and on signals from segmental receptors. The vestibular system may act to damp later response components and to monitor the position of the head in space secondary to feedback from segmental proprioceptors rather than to generate the postural reactions.

The Motion of Strawberry Leaves in an Air-Assisted Spray Field and its Influence on Droplet Deposition

2021 ◽  
Vol 64 (1) ◽  
pp. 83-93
Author(s):  
Shuo Wu ◽  
Jizhan Liu ◽  
Jiangshan Wang ◽  
Dianhe Hao ◽  
Rongkai Wang
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
High Amplitude ◽  
Azimuth Angle ◽  
List Type ◽  
Droplet Deposition ◽  
Inclination Angles ◽  
Turbulence Effect ◽  
Spray Field ◽  
Low Amplitude

HighlightsA visualization method for the motion of strawberry leaves in an air-assisted spray field is proposed.Strawberry leaves showed two motion states in different critical velocity ranges of the sprayer airflow.The airflow instability and the turbulence effect are considered important factors for the leaf vibrations.A strawberry leaf azimuth angle in the range of 90° to 270° can provide good deposition with smaller droplets.Abstract. The reasonable motion of crop plants in an air-assisted spray field can improve droplet deposition. Therefore, this study focuses on the motion of strawberry leaves and the droplet deposition mechanism in an air-assisted spray field. First, this study proposes a descriptive method for strawberry leaf motion in an air-assisted spray field and clarifies the important influence of strawberry leaf motion on droplet deposition. Second, an experiment was performed on the motion and droplet capture of single strawberry leaves in multi-position postures in an air-assisted spray field. The results showed that the leaves had two motion states (i.e., low amplitude with low frequency and high amplitude with high frequency) at different airflow velocities and inclination angles, and the critical airflow velocity corresponding to the two motion states was determined to be 8.7 m s-1. When the azimuth angle of the strawberry leaves is in the range of 90° to 270°, a reasonable inclination angle of the airflow and the high frequency and high amplitude vibration state of the leaves driven by the airflow will provide good deposition and canopy penetration of droplets with smaller diameters. Keywords: Air-assisted spray field, Droplet deposition, Motion, Spray, Strawberry leaves.

scholarly journals Impact of anaesthesia on static and dynamic functional connectivity in mice

2021 ◽  
Author(s):  
Tomokazu Tsurugizawa ◽  
Daisuke Yoshimaru
Keyword(s):  
Functional Connectivity ◽  
Functional Mri ◽  
Resting State ◽  
Low Frequency ◽  
Resting State Fmri ◽  
Brain Network ◽  
List Type ◽  
Thalamic Nuclei ◽  
Dynamic Functional Connectivity ◽  
Subcortical Regions

AbstractA few studies have compared the static functional connectivity between awake and anaesthetized states in rodents by resting-state fMRI. However, impact of anaesthesia on static and dynamic fluctuations in functional connectivity has not been fully understood. Here, we developed a resting-state fMRI protocol to perform awake and anaesthetized functional MRI in the same mice. Static functional connectivity showed a widespread decrease under anaesthesia, such as when under isoflurane or a mixture of isoflurane and medetomidine. Several interhemispheric connections were key connections for anaesthetized condition from awake. Dynamic functional connectivity demonstrates the shift from frequent broad connections across the cortex, the hypothalamus, and the auditory-visual cortex to frequent local connections within the cortex only. Fractional amplitude of low frequency fluctuation in the thalamic nuclei decreased under both anaesthesia. These results indicate that typical anaesthetics for functional MRI alters the spatiotemporal profile of the dynamic brain network in subcortical regions, including the thalamic nuclei and limbic system.HighlightsResting-state fMRI was compared between awake and anaesthetized in the same mice.Anaesthesia induced a widespread decrease of static functional connectivity.Anaesthesia strengthened local connections within the cortex.fALFF in the thalamus was decreased by anaesthesia.

scholarly journals Brain oscillations and connectivity in autism spectrum disorders (ASD): new approaches to methodology, measurement and modelling

2016 ◽  
Author(s):  
K. Kessler ◽  
R. A. Seymour ◽  
G. Rippon
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Autism Spectrum ◽  
List Type ◽  
Brain Oscillations ◽  
New Techniques ◽  
Low Frequencies ◽  
High Frequency Activity ◽  
Recent Classification ◽  
The Brain

AbstractAlthough atypical social behaviour remains a key characterisation of ASD, the presence of sensory and perceptual abnormalities has been given a more central role in recent classification changes. An understanding of the origins of such aberrations could thus prove a fruitful focus for ASD research. Early neurocognitive models of ASD suggested that the study of high frequency activity in the brain as a measure of cortical connectivity might provide the key to understanding the neural correlates of sensory and perceptual deviations in ASD. As our review shows, the findings from subsequent research have been inconsistent, with a lack of agreement about the nature of any high frequency disturbances in ASD brains. Based on the application of new techniques using more sophisticated measures of brain synchronisation, direction of information flow, and invoking the coupling between high and low frequency bands, we propose a framework which could reconcile apparently conflicting findings in this area and would be consistent both with emerging neurocognitive models of autism and with the heterogeneity of the condition.HighlightsSensory and perceptual aberrations are becoming a core feature of the ASD symptom prolife.Brain oscillations and functional connectivity are consistently affected in ASD.Relationships (coupling) between high and low frequencies are also deficient.Novel framework proposes the ASD brain is marked by local dysregulation and reduced top-down connectivityThe ASD brain’s ability to predict stimuli and events in the environment may be affectedThis may underlie perceptual sensitives and cascade into social processing deficits in ASD

scholarly journals Delta/theta band EEG differentially tracks low and high frequency speech-derived envelopes

2020 ◽  
Author(s):  
Felix Bröhl ◽  
Christoph Kayser
Keyword(s):  
High Frequency ◽  
Brain Activity ◽  
Low Frequency ◽  
List Type ◽  
Theta Band ◽  
Acoustic Fluctuations ◽  
Eeg Recordings ◽  
Band Limited ◽  
Speech Envelope ◽  
Speech Tracking

AbstractThe representation of speech in the brain is often examined by measuring the alignment of rhythmic brain activity to the speech envelope. To conveniently quantify this alignment (termed ‘speech tracking’) many studies consider the overall speech envelope, which combines acoustic fluctuations across the spectral range. Using EEG recordings, we show that using this overall envelope can provide a distorted picture on speech encoding. We systematically investigated the encoding of spectrally-limited speech-derived envelopes presented by individual and multiple noise carriers in the human brain. Tracking in the 1 to 6 Hz EEG bands differentially reflected low (0.2 – 0.83 kHz) and high (2.66 – 8 kHz) frequency speech-derived envelopes. This was independent of the specific carrier frequency but sensitive to attentional manipulations, and reflects the context-dependent emphasis of information from distinct spectral ranges of the speech envelope in low frequency brain activity. As low and high frequency speech envelopes relate to distinct phonemic features, our results suggest that functionally distinct processes contribute to speech tracking in the same EEG bands, and are easily confounded when considering the overall speech envelope.HighlightsDelta/theta band EEG tracks band-limited speech-derived envelopes similar to real speechLow and high frequency speech-derived envelopes are represented differentiallyHigh-frequency derived envelopes are more susceptible to attentional and contextual manipulationsDelta band tracking shifts towards low frequency derived envelopes with more acoustic detail

scholarly journals Toward Assessing Clinical Trial Publications for Reporting Transparency

2021 ◽  
Author(s):  
Halil Kilicoglu ◽  
Graciela Rosemblat ◽  
Linh Hoang ◽  
Sahil Wadhwa ◽  
Zeshan Peng ◽  
...  
Keyword(s):  
Text Mining ◽  
Majority Vote ◽  
Controlled Trial ◽  
Low Frequency ◽  
Support Vector ◽  
List Type ◽  
Learning Approaches ◽  
Annotation Scheme ◽  
Fine Grained ◽  
Mining Methods

AbstractObjectiveTo annotate a corpus of randomized controlled trial (RCT) publications with the checklist items of CONSORT reporting guidelines and using the corpus to develop text mining methods for RCT appraisal.MethodsWe annotated a corpus of 50 RCT articles at the sentence level using 37 fine-grained CONSORT checklist items. A subset (31 articles) was double-annotated and adjudicated, while 19 were annotated by a single annotator and reconciled by another. We calculated inter-annotator agreement at the article and section level using MASI (Measuring Agreement on Set-Valued Items) and at the CONSORT item level using Krippendorff’s α. We experimented with two rule-based methods (phrase-based and section header-based) and two supervised learning approaches (support vector machine and BioBERT-based neural network classifiers), for recognizing 17 methodology-related items in the RCT Methods sections.ResultsWe created CONSORT-TM consisting of 10,709 sentences, 4,845 (45%) of which were annotated with 5,246 labels. A median of 28 CONSORT items (out of possible 37) were annotated per article. Agreement was moderate at the article and section levels (average MASI: 0.60 and 0.64, respectively). Agreement varied considerably among individual checklist items (Krippendorff’s α= 0.06-0.96). The model based on BioBERT performed best overall for recognizing methodology-related items (micro-precision: 0.82, micro-recall: 0.63, micro-F1: 0.71). Combining models using majority vote and label aggregation further improved precision and recall, respectively.ConclusionOur annotated corpus, CONSORT-TM, contains more fine-grained information than earlier RCT corpora. Low frequency of some CONSORT items made it difficult to train effective text mining models to recognize them. For the items commonly reported, CONSORT-TM can serve as a testbed for text mining methods that assess RCT transparency, rigor, and reliability, and support methods for peer review and authoring assistance. Minor modifications to the annotation scheme and a larger corpus could facilitate improved text mining models. CONSORT-TM is publicly available at https://github.com/kilicogluh/CONSORT-TM.Graphical abstractHighlightsWe constructed a corpus of RCT publications annotated with CONSORT checklist items.We developed text mining methods to identify methodology-related check-list items.A BioBERT-based model performs best in recognizing adequately reported items.A phrase-based method performs best in recognizing infrequently reported items.The corpus and the text mining methods can be used to address reporting transparency.

scholarly journals Cephalometric Investigation of First Cervical Vertebrae Morphology and Hyoid Position in Young Adults with Different Sagittal Skeletal Patterns

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Seher Gündüz Arslan ◽  
Neval Dildeş ◽  
Jalen Devecioglu Kama
Keyword(s):  
Retrospective Study ◽  
Hyoid Bone ◽  
Sagittal Plane ◽  
Cervical Vertebrae ◽  
Class I ◽  
Vertical Position ◽  
Skeletal Pattern ◽  
Posterior Direction ◽  
Males And Females ◽  
Anterior Posterior

The aim of this retrospective study was to examine hyoid bone position and C1 (atlas) morphology in males and females and analyze these parameters with respect to different sagittal skeletal patterns via cephalometry, with the goal of identifying cephalometric norms. Lateral cephalometric radiographs from 120 individuals (average age: 21.1 ± 2.9 years) were classified according to their ANB angle (Class I, II, or III) and used to assess 14 parameters. Class I and II patients showed significant differences in Hy-NSL, Hy-PD, Hy-CVT, Lum, and a-p measurements. These parameters were consistently larger in males than in females. Intergroup comparisons among males showed significant differences in the SNA, ANB, Hy-CVT, X, and Z measurements. The hyoid was positioned more inferiorly and anteriorly and was more prominent in males than in females in all groups. Among participants exhibiting a Class I skeletal pattern, C1 was also larger in the anterior-posterior direction in males than in females. In the sagittal plane, the hyoid was positioned similarly in males with either Class I or III skeletal patterns but was positioned posteriorly in males with a Class II skeletal pattern. In addition, the vertical position of C1 varied with sagittal skeletal pattern in males.

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