Miracle-dz/UniFAR-FTUs huggingface dataset:
Spatiotemporal Models for Region of Interest Analyses of Functional Neuroimaging Data

In vivo functional neuroimaging technology enables the evaluation of behavior-related changes in measured brain activity within specific cortical regions of interest (ROIs). When sufficient neurophysiologic evidence exists to restrict attention to a defined cortical region, an ROI analysis can provide powerful insights regarding neural representations of cognition, emotions, behaviors, and the neuropathology of psychiatric disorders. Given the complexity and abundance of data from neuroimaging experiments, anatomically focused research questions allow statisticians to explore models that more accurately reflect neurophysiologic characteristics of the data than global activation studies. Neural processing characteristics of particular interest in this article are spatial correlations stemming from the interplay between spatially distinct brain locations and temporal correlations between serial measures of brain activity. Despite the simplified data structure of ROI studies, challenges remain in modeling spatial correlations due to, for example, the fact that the correlations do not necessarily decrease as a function of increasing separation between the measurement locations. This article presents a spatiotemporal model that incorporates a functionally defined distance metric into a parametric structure for spatial correlations and includes temporal correlations between repeated scans. We demonstrate the use of the spatiotemporal model using experimental data from a study of the effects of ethanol administration on brain activity in the cerebellum, which largely controls balance and posture. We further illustrate our model using data simulated from a study evaluating neural processing alterations in the right prefrontal cortex associated with mental arithmetic.
Double-gate organic field-effect transistor

We present a novel double-gate structure for polymeric field-effect transistors produced from a solution of [9,9]-dioctylfluorene-co-bithiophene copolymer (F8T2) as the p-type organic semiconductor. The double-gate geometry adapts to different bias configurations and shows improved performances and higher flexibility of operation with respect to single-gate devices. The device characteristics show an increased on/off ratio and demonstrate the possibility to control the threshold voltage as well as the off current. The maximum hole mobility of 8×10−2cm2∕Vs measured for the F8T2 layer, in combination with the features of the double-gate structure, suggest the possibility to produce optimized devices with very high performances.
Interpolation and denoising of high-dimensional seismic data by learning a tight frame

ABSTRACTSparse transforms play an important role in seismic signal processing steps, such as prestack noise attenuation and data reconstruction. Analytic sparse transforms (so-called implicit dictionaries), such as the Fourier, Radon, and curvelet transforms, are often used to represent seismic data. There are situations, however, in which the complexity of the data requires adaptive sparse transform methods, whose basis functions are determined via learning methods. We studied an application of the data-driven tight frame (DDTF) method to noise suppression and interpolation of high-dimensional seismic data. Rather than choosing a model beforehand (for example, a family of lines, parabolas, or curvelets) to fit the data, the DDTF derives the model from the data itself in an optimum manner. The process of estimating the basis function from the data can be summarized as follows: First, the input data are divided into small blocks to form training sets. Then, the DDTF algorithm is applied on the training set.
Weighted Modified Hu Moment in Human Behavior Recognition

t has been shown that the traditional seven Hu invariant moment does not have scaling invariance with low recognition rate in human behavior recognition. In order to improve the recognition rate, a human behavior recognition method will be put forward in this paper based on weighted modified Hu moments. Firstly, the traditional seven Hu moments will be extended to ten Hu moments to get more image details. Then, the extended Hu moments will be modified to make the Hu moments has the feature of scaling invariance. Lastly, the weighted modified Hu moment will be obtained through least squares method based on minimum variance criterion. The simulation of the sequence images shows that the weighted modified Hu moment can improve the recognition rate effectively.
MODELING OF HIGHLY CONDUCTING BOUNDARIES WITH TLM

Abstract Time–domain methods have the advantage to easily model media or boundaries which can be described or characterized in time–domain. However, constitutive parameters or impedance for instance are usually frequency–domain concepts and cannot be readily modeled with time–domain methods. Some investigation regarding the TLM modeling of a class of dispersive media, namely conducting media which have high conductivity, is proposed. Starting with a review of different techniques for modeling reflected signals from highly conducting boundaries, a procedure which uses an analytical formulation via Laplace transform is described in details. The interface with the TLM algorithm is discussed for transmitted as well as reflected signals. Asymptotic behavior of solutions is investigated and simplified formulae proposed. Some examples are given and compared to analytical solutions for validation.
Recent Changes Implemented into the Global Forecast System at NMC

Abstract A number of improvements were implemented on 6 March 1991 into the National Meteorological Center's global model, which is used in the global data assimilation system (GDAS), the aviation (AVN) forecast, and the medium-range forecast (MRF): The horizontal resolution of the forecast model was increased from triangular truncation T80 to T126, which corresponds to an equivalent increase in grid resolution from 160 km to 105 km. The use of enhanced orography has been discontinued and replaced by mean orography. A new marine-stratus parameterization was introduced. A new mass-conservation constraint was implemented. The horizontal diffusion in the medium scales was reduced by adopting the Leith formulation. A new, more accurate sea-surface temperature analysis is now used. In this note, we discuss each of the changes and briefly review the new model performance.
Cluster observations in the inner magnetosphere during the 18 April 2002 sawtooth event: Dipolarization and injection at r = 4.6 RE

[1] The present study examines a sawtooth injection event that took place around 0800 UT on 18 April 2002 when the Cluster spacecraft were located in the inner magnetosphere in the premidnight sector. In association with this injection, Cluster, at a radial distance of 4.6 RE, observed that the local magnetic field became more dipolar and that both ion and electron fluxes increased without notable energy dispersion. These features were accompanied by intensifications of the equatorward component of a double-oval structure and also by an enhancement of the ring-current oxygen ENA flux. The event was also accompanied by large magnetic field (a few tens of nT) and electric field (a few tens of mV/m) fluctuations with characteristic timescales of a few tens of seconds. These observations strongly suggest that this sawtooth injection extended not only widely in local time but also deeply into the inner magnetosphere. Interestingly, Cluster repeatedly observed dipolarization-like signatures afterward, which, however, were not associated with enhancements of local energetic ion flux or with geosynchronous dipolarization or injection signatures. Instead, these magnetic signatures were accompanied by oscillatory plasma motion in the radial direction with a characteristic timescale of about 10 min, which appears to be related to the westward propagation of a spatially periodic auroral structure. The associated azimuthal electric field component was well correlated with the time derivative of the north-south magnetic field component, suggesting that the observed electric field is inductive. These findings suggest that electromagnetic processes far inside geosynchronous orbit play an important role in energization of energetic ions and auroral dynamics during magnetospheric storms.
Nonparametric regression with censored covariates

The paper discusses weak convergence results for an estimate of the conditional survival function F(t z) = Pr(T> t Z = z) where T is a multivariate response variable and Z is a vector of covariates. It is assumed that both T and Z are subject to right censoring. The estimate is obtained by kernel smoothing the empirical analogue of a product integral representation of multivariate survival functions. Under regularity conditions we show that a standardized version of the regression estimate converges weakly to a mean zero Gaussian process and give the form of the asymptotic covariance in the case of univariate response variables. As a by product we also discuss asymptotic normality results for density estimates based on the smoothed product integral estimate.
Magnetohydrodynamic Vlasov simulation of the toroidal Alfven eigenmode

A new simulation method has been developed to investigate the excitation and saturation processes of toroidal Alfven eigenmodes (TAE modes). The background plasma is described by a magnetohydrodynamic (MHD) fluid model, while the kinetic evolution of energetic alpha particles is followed by the drift kinetic equation. The magnetic fluctuation of n=2 mode develops and saturates at the level of 1.8×10−3 of the equilibrium field when the initial beta of alpha particles is 2% at the magnetic axis. After saturation, the TAE mode amplitude shows an oscillatory behavior with a frequency corresponding to the bounce frequency of the alpha particles trapped by the TAE mode. The decrease of the power transfer rate from the alpha particles to the TAE mode, which is due to the trapped particle effect of a finite‐amplitude wave, causes the saturation. From the linear growth rate the saturation level can be estimated.
HST/FOS Spatially Resolved Spectral Classification of Compact OB Groups in the Large Magellanic Cloud

Blue-violet spectrograms of individual components in four compact OB groups of the Large Magellanic Cloud, obtained with the Hubble Space Telescope (HST) Faint Object Spectrograph (FOS), are presented and discussed. Two of the massive multiple systems are in the 30 Doradus periphery, while the other two represent the core and the peripheral, triggered associations in the giant shell H II region Henize N11. Uncontaminated spectrograms of three Wolf-Rayet and two very early Of components have been obtained for the first time; they can be observed only as composites with their close companions from the ground. Many of the companions have also been observed separately with the HST FOS, and several are of special interest in their own right. These observations provide information on the initial masses and ages of the peculiar objects, and on the evolutionary relationships among different spectral categories within the presumably coeval systems.
Nonradiative Recombination at Deep Levels in GaAs and GaP by Lattice-Relaxation Multiphonon Emission

Measurements of the temperature dependence of the carrier capture cross sections for ten deep levels in GaAs and GaP give strong evidence for nonradiative capture by lattice-relaxation multiphonon emission. A simple one-coordinate theory which takes into account the breakdown of the adiabatic approximation gives a good quantitative fit to the data.
Lynds 1527: An Embedded Protobinary System in Taurus

Submillimeter continuum maps at 800 μm of the embedded source IRAS 04368+2557 in L1527 in Taurus show that there are two sources separated by 20'', or 2800 AU. The secondary source is between 2 and 3 times less luminous than the primary source if both sources have similar spectral energy distributions. Large-scale C18O J = 1 → 0 emission shows the sources to be embedded in a single dense core, and observations of C18O and C17O show the sources to be associated with a compact region of high-density gas. Three transitions of C18O show a velocity gradient between the two sources. On the smallest size scale, the C18O J = 3 → 2 emission has a velocity gradient of 3-7 km s-1 pc-1. The proximity of the sources in both space and velocity suggest that they are a very young protobinary system. The estimated age of the primary source, 5 × 103 yr, is much less than the estimated orbital period, 1.4 × 105 yr. The separation and young age of the system indicates that it formed through fragmentation of the dense core during collapse.
Stepped-frequency continuous-wave microwave-induced thermoacoustic imaging

Microwave-induced thermoacoustic (TA) imaging combines the dielectric contrast of microwave imaging with the resolution of ultrasound imaging. Prior studies have only focused on time-domain techniques with short but powerful microwave pulses that require a peak output power in excess of several kilowatts to achieve sufficient signal-to-noise ratio (SNR). This poses safety concerns as well as to render the imager expensive and bulky with requiring a large vacuum radio frequency source. Here, we propose and demonstrate a coherent stepped-frequency continuous-wave (SFCW) technique for TA imaging which enables substantial improvements in SNR and consequently a reduction in peak power requirements for the imager. Constructive and destructive interferences between TA signals are observed and explained. Full coherency across microwave and acoustic domains, in the thermo-elastic response, is experimentally verified and this enables demonstration of coherent SFCW microwave-induced TA imaging. Compared to the pulsed technique, an improvement of 17 dB in SNR is demonstrated.
Temporal Order Judgment and Reaction Time

A model which predicts judgment of the temporal order of stimuli from simple reaction time is proposed. Visual data show covariation of the two measures with luminance changes, and suggest that (i) temporal order judgments reflect a biased response criterion and (ii) the motor component of reaction time has little variability relative to variance in receptor system latency.
On the Estimation of Sparse Hessian Matrices

This paper studies automatic procedures for estimating second derivatives of a real valued function of several variables. The estimates are obtained from differences in first derivative vectors, and it is supposed that the required matrix is sparse and that its sparsity structure is known. Our main purpose is to find ways of taking advantage of the sparsity structure and the symmetry of the second derivative matrix, in order to make small the number of first derivative vectors that have to be calculated. Two new algorithms are proposed, which seem to be very successful in practice and which do not require much computer arithmetic. One is a direct method and the other is a substitution method, these terms being explained in the paper. Some examples show, however, that the given methods may not minimize the number of first derivative vector calculations.
Linear optical birefringence of magnetic crystals

The study of changes in the refractive indices (with consequent changes of birefringence) of a transparent magnetic crystal which accompany changes in the magnetic order is becoming more popular. The authors review why this is. The first reason is that birefringence can be measured very accurately: the different experimental arrangements are reviewed. The second reason is because a birefringence measurement is an integrational spectroscopic technique and therefore it is studied both experimentally and theoretically as a branch of magneto-optics and hence gives information on the detailed energy level structure of the solid. The third reason is that in a number of interesting systems the birefringence is proportional to the magnetic energy over a wide temperature range and it is often a more convenient method of obtaining the magnetic specific heat than direct specific heat measurements; this is particularly true in magnetic crystals which show low dimensional ordering. The last reason is that in all magnetic crystals the birefringence change should vary like one of the thermodynamic critical exponents near to the phase transition. They review in detail the reasons why birefringence studies have become so successful for measuring critical exponents in pure and particularly mixed crystals.
Dynamical approach to complementarity of interferometers

The complementarity for wave-like and particle-like properties of a quantum mechanical particle in the Mach–Zehnder interferometer is investigated by means of the dynamical approach. Measurement devices are placed on the paths of the interferometer to obtain the information of a propagating particle. The which-path information of the particle and the fringe visibility of the interferometer are derived by considering the dynamics of the particle and devices. When each device consists of a single qubit, the maximum amount of the which-path information is obtained and the complementary relation is examined.
A near-infrared imaging survey of interacting galaxies - The disk-disk merger candidates subset

Near-infrared imaging obtained for systems believed to be advanced disk-disk mergers are presented and discussed. These systems were chosen from a sample of approximately 170 objects from the Arp Atlas of Peculiar Galaxies which have been imaged in the JHK bands as part of an investigation into the stellar component of interacting galaxies. Of the eight remnants which show optical signs of a disk-disk merger, the near-infrared surface brightness profiles are well-fitted by an r exp 1/4 law over all measured radii in four systems, and out to radii of about 3 kpc in three systems. These K band profiles indicate that most of the remnants in the sample either have finished or are in the process of relaxing into a mass distribution like that of normal elliptical galaxies. 20 refs.
A two color multichord infrared interferometer for RFX

A multichord interferometer designed for the Reversed Field experiment (RFX) (R=2 m, a=0.5 m, I=2 MA) is presented. The high density expected and the rather limited diagnostic access to the plasma motivated the choice of a two‐color CO2/CO laser (10.6/5.4 μm) interferometer. Due to the time‐varying magnetic fields ≥0.1 T around the torus entailed by the operation of the machine, the system has been mounted on a 3 ton graphite C‐shaped optical table supported by a stainless steel structure on pneumatic vibration isolators. This led to long term stability of alignment and a very low level of mechanical vibrations. The interferometer can be moved in and out of the torus with ease by a carriage‐rail system for maintenance both of the diagnostic and of the machine. The design foresees eight vertical chords spanning the arms of the C‐shaped table and includes more additional measurements using a horizontal port and mirrors mounted inside the vacuum chamber. The expected accuracy in line density units is ≤1×1018.
First-principles investigation of Ca 3 (Ti, Zr, Hf, Sn) 2 Fe 2 SiO 12 garnet structure for incorporation of actinides

The structure, electronic structure, and bonding properties of Ca{sub 3} (Ti,Zr,Hf,Sn){sub 2} Fe{sub 2} SiO{sub 12} garnets have been investigated using ab initio electronic structure methods within density functional theory. The incorporation mechanisms of U into different sites of garnet with different compositions have been investigated. In order to describe the behavior of the localized Fe d and U f states, we employed the local spin density approximation (LSDA)+U method. The theoretical unit cell parameters and (cation-O) bond lengths for the four compositions are in good agreement with available experimental data. The calculated densities of states of all garnet compositions investigated are quite similar, suggesting only minor differences in the cation-O interactions. The analysis of the charge density using Bader’s scheme suggests that the (Hf-O) bond has the most ionic character, while the (Ti-O) bond is more covalent. This result provides some insight into the radiation response of the garnet structure. Based on total energy calculations, U preferentially occupies the octahedral site in the garnet structure. The lowest incorporation energy occurs when U substitutes for Sn in the octahedral site. In order to accommodate U at the dodecahedral site (i.e., substituting for Ca), some partial electron transfer from the Umore » to the Fe ions is necessary, making U incorporation in this site unfavorable. « less
Nonlinear vibration analysis of piezo-actuated flat thin membrane

Minimal mass (ultra lightweight) and high packaging efficiency (stowage volume) are the most important factors associated with space technology and hence they become more attractive traits for getting larger bandwidth satellites on-orbit. Nowadays, maintaining the surface shape of pre-tension membranes to instrument precision has become a more challenging problem. Hence, membrane reflectors are receiving increasing attention for mission architectures that need extremely large in-space deployable antennas. This paper presents the finite-element investigation of a rectangular, flat thin membrane using polyvinylidene fluoride (PVDF) piezo-actuated material as an actuator/sensor. The passive effect of PVDF on the dynamics of an inflatable space-based rectangular shaped structure has been studied and trends in natural frequencies for various patch areas and thickness have been explored. Investigation shows that rather than using the various numbers of patches to the practical system for controlling their vibration behavior, the single patch with the appropriate thickness can easily control the desired vibration behavior. It can therefore be concluded that the discrete sensor/actuators devices are to be preferred to realize lower weight and effective control authority for the modest values of actuator voltages for active vibration control of practical structures.
Nonlinear dimensionality reduction of data by multilayer bootstrap networks

Learning invariant semantic concepts from highly-variant high-dimensional data is a very important problem in many research fields. If we encode the data and concepts compactly by for example 0 and 1, the golden pathway is a problem of reducing high-dimensional codes to low-dimensional representations. Dimensionality reduction, as a central problem of statistics and machine learning, has been intensively studied, where classification and clustering are two special cases of dimensionality reduction that reduce high-dimensional data to discrete points. Bootstrap resampling is a simple and fundamental method in statistics, and has achieved a great success in supervised dimensionality reduction. However, bootstrap based unsupervised dimensionality reduction methods were still not powerful compared to kernel methods and neural networks. Here we describe a simple multilayer bootstrap network for unsupervised dimensionality reduction that each layer of the network is a group of mutually independent k-centers clusterings, and the centers are only randomly sampled data points. We find that the described simple method outperformed 7 well-known unsupervised dimensionality reduction methods on both very small-scale biomedical data and large-scale image and document data with less training time than multilayer neural networks on large-scale data. Our findings generalized bootstrap to unsupervised dimensionality reduction successfully and enriched the family of bootstrap methods. Furthermore, given the broad use of simple methods, the described method, which may be easily understood without domain knowledge, can find its applications in many scientific research fields.