scholarly journals Suprathreshold perceptual decisions constrain models of confidence

2021 ◽  
Author(s):  
Shannon M Locke ◽  
Michael S Landy ◽  
Pascal Mamassian
Keyword(s):  
Signal To Noise Ratio ◽  
Point Estimate ◽  
Probability Metrics ◽  
Evidence Strength ◽  
Discrimination Criterion ◽  
Best Fitting ◽  
Complex Decision ◽  
The Mean ◽  
Sensory Uncertainty ◽  
Best Fit

Perceptual confidence is an important internal signal about the certainty of our decisions and there is a substantial debate on how it is computed. We highlight three confidence metric types from the literature: observers either use 1) the full probability distribution to compute probability correct (Probability metrics), 2) point estimates from the perceptual decision process to estimate uncertainty (Evidence-Strength metrics), or 3) heuristic confidence from stimulus-based cues to uncertainty (Heuristic metrics). These metrics are rarely tested against one another, so we examined models of all three types on a suprathreshold spatial discrimination task. Observers were shown a cloud of dots sampled from a dot generating distribution and judged if the mean of the distribution was left or right of centre. In addition to varying the horizontal position of the mean, there were two sensory uncertainty manipulations: the number of dots sampled and the spread of the generating distribution. After every two perceptual decisions, observers made a confidence forced-choice judgement whether they were more confident in the first or second decision. Model results showed that observers were on average best-fit by a Heuristic model that used dot cloud position, spread, and number of dots as cues. However, almost half of the observers were best-fit by an Evidence-Strength model that uses the distance between the discrimination criterion and a point estimate, scaled according to sensory uncertainty, to compute confidence. This signal-to-noise ratio model outperformed the standard unscaled distance from criterion model favoured by many researchers and suggests that this latter simple model may not be suitable for mixed-difficulty designs. An accidental repetition of some sessions also allowed for the measurement of confidence agreement for identical pairs of stimuli. This N-pass analysis revealed that human observers were more consistent than their best-fitting model would predict, indicating there are still aspects of confidence that are not captured by our model. As such, we propose confidence agreement as a useful technique for computational studies of confidence. Taken together, these findings highlight the idiosyncratic nature of confidence computations for complex decision contexts and the need to consider different potential metrics and transformations in the confidence computation.

016 Associations between Circadian Melatonin and Temperature Amplitudes during Constant Routine

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A8-A8
Author(s):  
Katrina Rodheim ◽  
Christoper Jung ◽  
Kenneth Wright
Keyword(s):  
Individual Differences ◽  
Regression Models ◽  
Signal To Noise Ratio ◽  
Large Individual ◽  
Linear Regression Models ◽  
Harmonic Model ◽  
Circadian Phase ◽  
Best Fitting ◽  
Harmonic Regression ◽  
Best Fit

Abstract Introduction Circadian amplitude measures the strength or robustness of a rhythm and changes in amplitude may have implications for health. Large individual differences in melatonin amplitude are recognized. Here we aimed to determine the strength of relationships between melatonin and the core body (CBT) and distal-proximal skin temperature gradient (DPG) amplitudes during a constant routine protocol. Additionally, we determined the best fitting harmonic model for the DPG circadian rhythm. Methods 17 young healthy adults [13 males (22.3±3.9yr;mean±SD)] completed a 28-hr constant routine protocol after maintaining 8h habitual sleep schedules for one week at home. Endogenous circadian amplitudes of melatonin and CBT were fit with standard three- and dual-harmonic linear regression models, respectively. The DPG amplitude was analyzed with both dual and three-harmonic regression models to determine which model produced the best fit. Results The DPG was best fit by a three-harmonic regression model with significantly lower standard deviation and higher signal-to-noise ratio compared to the 2-harmonic model (both p<0.05) as well as by visualization of the fitted curves. Melatonin, CBT and DPG amplitudes were not found to be associated with each other during constant routine (all r<0.37; all p>0.10). Conclusion While it is common for melatonin and body temperature circadian phase estimates to be used interchangeably, non-significant findings for associations between circadian amplitudes of melatonin, CBT and DPG indicate that these markers may not provide similar information about circadian amplitude. Further, research is needed to explore possible associations between individual differences in melatonin, CBT and DPG amplitudes with other physiological and behavioral outcomes to determine which measure(s) of circadian amplitude may be functionally relevant. Support (if any) NIH R01 HL081761

scholarly journals Optimization of SPECT/CT imaging protocols for quantitative and qualitative 99mTc SPECT

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Dennis Kupitz ◽  
Heiko Wissel ◽  
Jan Wuestemann ◽  
Stephanie Bluemel ◽  
Maciej Pech ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Quantitative Imaging ◽  
Scatter Correction ◽  
Reconstruction Algorithm ◽  
Weighting Factor ◽  
Quantitative Spect ◽  
Pet Ct ◽  
Spect Acquisition ◽  
The Mean ◽  
A Minor

Abstract Background The introduction of hybrid SPECT/CT devices enables quantitative imaging in SPECT, providing a methodological setup for quantitation using SPECT tracers comparable to PET/CT. We evaluated a specific quantitative reconstruction algorithm for SPECT data using a 99mTc-filled NEMA phantom. Quantitative and qualitative image parameters were evaluated for different parametrizations of the acquisition and reconstruction protocol to identify an optimized quantitative protocol. Results The reconstructed activity concentration (ACrec) and the signal-to-noise ratio (SNR) of all examined protocols (n = 16) were significantly affected by the parametrization of the weighting factor k used in scatter correction, the total number of iterations and the sphere volume (all, p < 0.0001). The two examined SPECT acquisition protocols (with 60 or 120 projections) had a minor impact on the ACrec and no significant impact on the SNR. In comparison to the known AC, the use of default scatter correction (k = 0.47) or object-specific scatter correction (k = 0.18) resulted in an underestimation of ACrec in the largest sphere volume (26.5 ml) by − 13.9 kBq/ml (− 16.3%) and − 7.1 kBq/ml (− 8.4%), respectively. An increase in total iterations leads to an increase in estimated AC and a decrease in SNR. The mean difference between ACrec and known AC decreased with an increasing number of total iterations (e.g., for 20 iterations (2 iterations/10 subsets) = − 14.6 kBq/ml (− 17.1%), 240 iterations (24i/10s) = − 8.0 kBq/ml (− 9.4%), p < 0.0001). In parallel, the mean SNR decreased significantly from 2i/10s to 24i/10s by 76% (p < 0.0001). Conclusion Quantitative SPECT imaging is feasible with the used reconstruction algorithm and hybrid SPECT/CT, and its consistent implementation in diagnostics may provide perspectives for quantification in routine clinical practice (e.g., assessment of bone metabolism). When combining quantitative analysis and diagnostic imaging, we recommend using two different reconstruction protocols with task-specific optimized setups (quantitative vs. qualitative reconstruction). Furthermore, individual scatter correction significantly improves both quantitative and qualitative results.

scholarly journals Helium, [Fe/H] Abundances and the HR (Log TEFF, MBol) Diagram With Hipparcos Data of The Four Nearest Open Clusters: Hyades, Coma Berenices, The Pleiades and Praesepe

1998 ◽  
Vol 11 (1) ◽  
pp. 565-565
Author(s):  
G. Cayrel de Strobel ◽  
R. Cayrel ◽  
Y. Lebreton
Keyword(s):  
Main Sequence ◽  
Open Clusters ◽  
Main Sequence Stars ◽  
Spectroscopic Analyses ◽  
Solar Metallicity ◽  
Metal Abundances ◽  
The Mean ◽  
The Moment ◽  
The One ◽  
Best Fit

After having studied in great detail the observational HR diagram (log Teff, Mbol) composed by 40 main sequence stars of the Hyades (Perryman et al.,1997, A&A., in press), we have tried to apply the same method to the observational main sequences of the three next nearest open clusters: Coma Berenices, the Pleiades, and Praesepe. This method consists in comparing the observational main sequence of the clusters with a grid of theoretical ZAMSs. The stars composing the observational main sequences had to have reliable absolute bolometric magnitudes, coming all from individual Hipparcos parallaxes, precise bolometric corrections, effective temperatures and metal abundances from high resolution detailed spectroscopic analyses. If we assume, following the work by Fernandez et al. (1996, A&A,311,127), that the mixing-lenth parameter is solar, the position of a theoretical ZAMS, in the (log Teff, Mbol) plane, computed with given input physics, only depends on two free parameters: the He content Y by mass, and the metallicity Z by mass. If effective temperature and metallicity of the constituting stars of the 4 clusters are previously known by means of detailed analyses, one can deduce their helium abundances by means of an appropriate grid of theoretical ZAMS’s. The comparison between the empirical (log Teff, Mbol) main sequence of the Hyades and the computed ZAMS corresponding to the observed metallicity Z of the Hyades (Z= 0.0240 ± 0.0085) gives a He abundance for the Hyades, Y= 0.26 ± 0.02. Our interpretation, concerning the observational position of the main sequence of the three nearest clusters after the Hyades, is still under way and appears to be greatly more difficult than for the Hyades. For the moment we can say that: ‒ The 15 dwarfs analysed in detailed in Coma have a solar metallicity: [Fe/H] = -0.05 ± 0.06. However, their observational main sequence fit better with the Hyades ZAMS. ‒ The mean metallicity of 13 Pleiades dwarfs analysed in detail is solar. A metal deficient and He normal ZAMS would fit better. But, a warning for absorption in the Pleiades has to be recalled. ‒ The upper main sequence of Praesepe, (the more distant cluster: 180 pc) composed by 11 stars, analysed in detail, is the one which has the best fit with the Hyades ZAMS. The deduced ‘turnoff age’ of the cluster is slightly higher than that of the Hyades: 0.8 Gyr instead of 0.63 Gyr.

TOP-PRO study: A randomized double-blind controlled trial of topiramate versus propranolol for prevention of chronic migraine

Cephalalgia ◽  
2021 ◽  
pp. 033310242110474
Author(s):  
Debashish Chowdhury ◽  
Luv Bansal ◽  
Ashish Duggal ◽  
Debabrata Datta ◽  
Ankit Mundra ◽  
...  
Keyword(s):  
Adverse Events ◽  
Chronic Migraine ◽  
Virus Disease ◽  
Controlled Trial ◽  
Preventive Treatment ◽  
Point Estimate ◽  
Tolerability Profile ◽  
Double Blind ◽  
Significant Difference ◽  
The Mean

Objective The aim of the TOP-PRO-study, a double-blind randomized controlled trial, was to assess the efficacy (non-inferiority) and tolerability of propranolol compared to topiramate for the prevention of chronic migraine. Background Except for topiramate, oral preventive treatment for chronic migraine lacks credible evidence. Methods Chronic migraine patients aged above 18 years and less than 65 years of age, not on any preventive treatment were randomly allocated to receive topiramate (100 mg/day) or propranolol (160 mg/day). The primary efficacy outcome was the mean change in migraine days per 28 days at the end of 24 weeks from baseline. A mean difference of 1.5 days per four weeks was chosen as the cut-off delta value. Multiple secondary efficacy outcomes and treatment emergent adverse events were also assessed. Results As against the planned sample size of 244, only 175 patients could be enrolled before the spread of the corona virus disease-2019 pandemic and enforcement of lockdown in India. Of the 175 randomized patients, 95 (topiramate 46 and propranolol 49) completed the trial. The mean change in migraine days was −5.3 ± 1.2 vs −7.3 ± 1.1 days (p = 0.226) for topiramate and propranolol groups respectively. Propranolol was found to be non-inferior and not superior to topiramate (point estimate of −1.99 with a 95% confidence interval of −5.23 to 1.25 days). Multiple secondary outcomes also did not differ between the two groups. Intention to treat analysis of 175 patients and per-protocol analysis of 95 patients yielded concordant results. There was no significant difference in the incidence of adverse events between the two groups. Conclusion Propranolol (160mg/day) was non-inferior, non-superior to topiramate (100mg/day) for the preventive treatment of chronic migraine and had a comparable tolerability profile. Trial Registration: Clinical Trials Registry-India CTRI/2019/05/018997)

scholarly journals Hemispherical variance anomaly and reionization optical depth

2020 ◽  
Vol 499 (3) ◽  
pp. 3563-3570
Author(s):  
Márcio O’Dwyer ◽  
Craig J Copi ◽  
Johanna M Nagy ◽  
C Barth Netterfield ◽  
John Ruhl ◽  
...  
Keyword(s):  
Optical Depth ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Signal To Noise Ratio ◽  
Cosmological Parameters ◽  
Temperature Data ◽  
Microwave Background ◽  
Parameter Uncertainties ◽  
Polarization Data ◽  
Best Fitting

ABSTRACT Cosmic microwave background (CMB) full-sky temperature data show a hemispherical asymmetry in power nearly aligned with the Ecliptic, with the Northern hemisphere displaying an anomalously low variance, while the Southern hemisphere appears consistent with expectations from the best-fitting theory, Lambda Cold Dark Matter (ΛCDM). The low signal-to-noise ratio in current polarization data prevents a similar comparison. Polarization realizations constrained by temperature data show that in ΛCDM the lack of variance is not expected to be present in polarization data. Therefore, a natural way of testing whether the temperature result is a fluke is to measure the variance of CMB polarization components. In anticipation of future CMB experiments that will allow for high-precision large-scale polarization measurements, we study how the variance of polarization depends on ΛCDM-parameter uncertainties by forecasting polarization maps with Planck’s Markov chain Monte Carlo chains. We show that polarization variance is sensitive to present uncertainties in cosmological parameters, mainly due to current poor constraints on the reionization optical depth τ, which drives variance at low multipoles. We demonstrate how the improvement in the τ measurement seen between Planck’s two latest data releases results in a tighter constraint on polarization variance expectations. Finally, we consider even smaller uncertainties on τ and how more precise measurements of τ can drive the expectation for polarization variance in a hemisphere close to that of the cosmic-variance-limited distribution.

scholarly journals 2D In-Plane Sensitive Hall-Effect Sensor

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 711
Author(s):  
Siya Lozanova ◽  
Ivan Kolev ◽  
Avgust Ivanov ◽  
Chavdar Roumenin
Keyword(s):  
Hall Effect ◽  
Signal To Noise Ratio ◽  
Hall Effect Sensor ◽  
Orthogonal Components ◽  
The Mean ◽  
The Cross ◽  
The Magnetic Field ◽  
Outer Contact ◽  
Hall Elements ◽  
Ic Technology

A new 2D (two-dimensional) in-plane sensitive Hall-effect sensor comprising two identical n-Si Greek-crosses is presented. Each of the crosses contains one central square contact and, symmetrically to each of their four sides, an outer contact is available. Outer electrode from one configuration is connected with the respective opposite contact from the other configuration, thus forming four parallel three-contact (3C) Hall elements. These original connections provide pairs of opposite supply currents in each of the cross-Hall structure. Also the obligatory load resistors in the outer contacts of 3С Hall elements are replaced by internal resistances of crosses themselves. The samples have been implemented by IC technology, using four masks. The magnetic field is parallel to the structures’ plane. The couples of opposite contacts of each Greek-cross are the outputs for the two orthogonal components of the magnetic vector at sensitivities S ≈ 115 V/AT whereas the cross-talk is very promising, reaching no more than 2.4%. The mean lowest detected magnetic induction B at a supply current Is = 3 mA over the frequency range f ≤ 500 Hz at a signal to noise ratio equal to unity, is Bmin ≈ 14 μT.

scholarly journals Adaptive Noise Cancellation of an Analog Fiber Optic Link

2021 ◽  
Author(s):  
Mohammad Nazrul Islam
Keyword(s):  
Optical Fiber ◽  
Fiber Optic ◽  
Signal To Noise Ratio ◽  
Optical Power ◽  
Noise Cancellation ◽  
Adaptive Noise Cancellation ◽  
Fiber Link ◽  
The Mean ◽  
Simulation Results ◽  
Adaptive Noise

There are three dominant noise mechanisms in an analog optical fiber link. These are shot noise that is proportional to the mean optical power, relative intensity noise (RIN) that is proportional to the square of the instanteaneous optical power. This report describes an adaptive noise cancellation of these dominant noise processes that persist an analog optical fiber link. The performance of an analog optical fiber link is analyzed by taking the effects of these noise processes. Analytical and simulation results show that some improvement in signal to noise ratio (SNR) and this filter is effective to remove noise adaptively from the optical fiber link.

scholarly journals Thermal annealing of implanted <sup>252</sup>Cf fission tracks in monazite

Geochronology ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 89-102
Author(s):  
Sean Jones ◽  
Andrew Gleadow ◽  
Barry Kohn
Keyword(s):  
Thermal Annealing ◽  
Fission Track ◽  
Closure Temperature ◽  
Fission Tracks ◽  
Temperature Ranges ◽  
Best Fitting ◽  
The Mean ◽  
Oriented Parallel ◽  
Increasing Temperature ◽  
Ambient Surface

Abstract. A series of isochronal heating experiments were performed to constrain monazite fission track thermal annealing properties. The 252Cf fission tracks were implanted into monazite crystals from the Devonian Harcourt granodiorite (Victoria, Australia) on polished surfaces oriented parallel to (100) pinacoidal faces and perpendicular to the crystallographic c axis. Tracks were annealed over 1, 10, 100 and 1000 h schedules at temperatures between 30 and 400 ∘C. Track lengths were measured on captured digital image stacks and then converted to calculated mean lengths of equivalent confined fission tracks that progressively decreased with increasing temperature and time. Annealing is anisotropic, with tracks on surfaces perpendicular to the crystallographic c axis consistently annealing faster than those parallel to the (100) face. To investigate how the mean track lengths decreased as a function of annealing time and temperature, one parallel and two fanning models were fitted to the empirical dataset. The temperature limits of the monazite partial annealing zone (MPAZ) were defined as length reductions to 0.95 (lowest) and 0.5 (highest) for this study. Extrapolation of the laboratory experiments to geological timescales indicates that for a heating duration of 107 years, estimated temperature ranges of the MPAZ are −44 to 101 ∘C for the parallel model and −71 to 143 ∘C (both ±6–21 ∘C, 2 standard errors) for the best-fitting linear fanning model (T0=∞). If a monazite fission track closure temperature is approximated as the midpoint of the MPAZ, these results, for tracks with similar mass and energy distributions to those involved in spontaneous fission of 238U, are consistent with previously estimated closure temperatures (calculated from substantially higher energy particles) of < 50 ∘C and perhaps not much higher than ambient surface temperatures. Based on our findings we estimate that this closure temperature (Tc) for fission tracks in monazite ranges between ∼ 45 and 25 ∘C over geological timescales of 106–107 years, making this system potentially useful as an ultra-low-temperature thermochronometer.

scholarly journals Development of the Persian version of high-frequency emphasis quick speech in noise

2019 ◽  
Author(s):  
Jamileh Fatahi ◽  
Maryam Amiri Jahromi ◽  
Fahimeh Hajiabolhassan ◽  
Amirsalar Jafarpisheh ◽  
Nariman Rahbar ◽  
...  
Keyword(s):  
High Frequency ◽  
Signal To Noise Ratio ◽  
Mean Value ◽  
Small Sample ◽  
Test Reliability ◽  
Face Validity ◽  
Mean Values ◽  
Speech In Noise ◽  
Persian Version ◽  
The Mean

Background and Aim: The quick speech in noise (Q-SIN) test shows the difficulty of spee­ch perception in noise by specifying signal to noise ratio (SNR) loss. Although the Persian version of Q-SIN has been already constructed, the high-frequency emphasis version of this test is not available. The present study aimed to construct six lists with high-frequency emphasis and implement it. Methods: We are going to prepare a high-frequ­ency emphasis version of Q-SIN and then test it on a small sample. First, researchers designed the relevant sentences; then experts examined their content and face validity. According to the criteria for developing the Q-SIN test, six lists with high-frequency emphasis were prepared. The test was examined on 26 (13 male and 13 female), 18−35 years old individuals with nor­mal hearing. To determine the test reliability, it was re-administered three weeks later with the same conditions. Results: Of 76 sentences prepared, 36 sentences received enough credit after determination of their content and face validity. These 36 senten­ces were used to make 6 lists. The mean value of SNR50 in the Persian language was obtained -4 dB. The mean values of SNR loss in 6 lists were -1.65, -1.8, -2.23, -1.61, -2.38 and -2.07. The results showed equivalency of lists 1, 2, 3, 4, and 6. Examination of test-retest reliability indicated that all lists except the list 2were reliable. Conclusion: The lists of 1, 3, 4, and 6 are reli­able and equivalent and can be used in clinical application.

PMTools – a new program for paleomagnetic data analysis and visualization

2021 ◽  
Author(s):  
Ivan Efremov ◽  
Roman Veselovskiy
Keyword(s):  
Data Analysis ◽  
Paleomagnetic Data ◽  
Use Case ◽  
Quality Performance ◽  
Analysis Process ◽  
Data Formats ◽  
Cross Platform ◽  
The Mean ◽  
Near Future ◽  
Best Fit

&lt;p&gt;There are many programs for the analysis and visualization of paleomagnetic data, but each of them is good only in a certain use case and does not allow to perform a full cycle of paleomagnetic operations. Therefore, one has to resort to using a number of programs to complete the full path of processing paleomagnetic data. You often have to convert data from one format to another, manually vectorize charts, and generally spend more time and effort than could theoretically be spent. Thus, there is a long overdue need for a universal program capable of fast, convenient and high-quality performance of a full cycle of paleomagnetic operations. A set of programs written by Randy Enkin (Enkin, 1996) for DOS was taken as a time-tested example of such a program. The choice fell on them, since these programs (although they are very outdated) allow performing a full cycle of paleomagnetic operations and do it as conveniently and efficiently as possible for that time.&lt;/p&gt;&lt;p&gt;Our goal is to create a program devoid of all of the above disadvantages and capable of developing indefinitely as modular opensource software by the efforts of all people interested in this.&lt;/p&gt;&lt;p&gt;The result of our work is PMTools &amp;#8211; a cross-platform software for statistical analysis and visualization of paleomagnetic data. PMTools supports all widely used paleomagnetic data formats and allows you to work with them simultaneously. All charts created in PMTools are vector, adapted for direct using in publications and presentations, and can be exported in both vector and raster formats. At the same time, PMTools implements a full cycle of routine paleomagnetic operations: from finding the best-fit directions to calculating the mean paleomagnetic poles. Moreover, all operations can be performed both with a mouse through a graphical user interface and with hotkeys, which significantly speeds up the data analysis process.&amp;#160;&lt;/p&gt;&lt;p&gt;In the near future, PMTools will become a modular open source application, so that each user will be able to add its own modules, thereby expanding the program's functionality.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Enkin, R.J., 1996. A Computer Program Package for Analysis and Presentation of Paleomagnetic Data, Pacific Geoscience Center, Geological Survey of Canada, http://www.pgc.nrcan.gc.ca/tectonic/enkin.htm.&lt;/p&gt;

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