Target Amplitude Research Articles

Sequential Monte Carlo Cardinalized probability hypothesized density filter based on Track-Before-Detect for fluctuating targets in heavy-tailed clutter

In this paper, a Sequential Monte Carlo Cardinalized Probability Hypothesized Density (SMC-CPHD) filter based on Track-Before-Detect (TBD) algorithm in heavy-tailed clutter is proposed. The CPHD filter, which jointly propagates the first-order statistical moment and cardinality distribution, is an effective and efficient solution to multitarget filter problem in the presence of data association uncertainty, detect uncertainty, and time-varying. The TBD algorithm is extremely sensitive to the presence of clutter spikes in the data as the formulation of the TBD filter is dependent on knowledge of underlying clutter behavior. Therefore, the clutter is modeled in terms of K distribution with sea surface background and G0 distribution with primary forest background, while the popular Swerling targets of type 1 and 3 are considered to capture the target amplitude fluctuation frame-to-frame in this paper. The utilization of K distribution and G0 distribution clutter models instead of conventional Rayleigh distribution are verified through analysis of simulated and realistic data. The relevant results prove that proposed SMC-CPHD-TBD algorithm based on K distribution model and G0 distribution model can improve the detect and tracking performance over the conventional method in heavy-tailed clutter scenario. Additionally, the numerical simulations show that proposed CPHD-TBD algorithm can output the multitarget trajectories in the better precision with considerably less computational complexity compared with DP-TBD algorithm.

Reflection in-line and off-axis hybrid digital holography

We propose an in-line and off-axis hybrid holographic method for imaging reflective objects. The in-line and off-axis digital holograms are recorded by a Michelson interferometer. The approximate phase of object wave is obtained by spectral filtering approach from the off-axis hologram, and it is used as an initial input in an iterative procedure for retrieving the complex field of the object from the in-line hologram. In this way, the output of the iterative procedure can produce higher quality amplitude and phase images compared to only in-line or off-axis digital holography. The performance of this method has been demonstrated by acquiring the amplitude and phase images of a resolution target and a microelectronic chip.

Antipointing Reaches Do Not Adhere to Width-Based Manipulations of Fitts’ (1954) Equation

Reaches with overlapping stimulus-response spatial relations (propointing) adhere to speed-accuracy relations as defined by Paul Fitts' index of difficulty equation (IDFitts: in bits of information). This movement principle is attributed to response mediation via the "fast" visuomotor networks of the dorsal visual pathway. It is, however, unclear whether the executive demands of dissociating stimulus-response spatial relations by reachingmirror-symmetrical to a target (antipointing) elicits similar adherence to Fitts' equation. Here, pro- and antipointing responses were directed to a constant target amplitude with varying target widths to provide IDFitts values of 3.0, 3.5, 4.3, and 6.3 bits. Propointing movement times linearly increased with IDFitts-a result attributed to visually based trajectory corrections. In contrast, antipointing movement times, deceleration times, and endpoint precision did not adhere to Fitts' equation. These results indicate that antipointing renders a "slow" and offline mode of control mediated by the visuoperceptual networks of the ventral visual pathway.

Intrafraction 4D-cone beam CT acquired during volumetric arc radiotherapy delivery: kV parameter optimization and 4D motion accuracy for lung stereotactic body radiotherapy (SBRT) patients.

PurposeElekta XVI 5.0 allows for four‐dimensional cone beam computed tomography (4D CBCT) image acquisition during treatment delivery to monitor intrafraction motion. These images can have poorer image quality due to undersampling of kV projections and treatment beam MV scatter effects. We determine if a universal intrafraction preset can be used for stereotactic body radiotherapy (SBRT) lung patients and validate the accuracy of target motion characterized by XVI intrafraction 4D CBCT.MethodsThe most critical parameter within the intrafraction preset is the nominal AcquisitionInterval, which controls kV imaging acquisition frequency. An optimal value was determined by maximizing the kV frame number acquired up to 1000 frames, typical of pretreatment 4D CBCT. CIRS motion phantom intrafraction phase images for 16 SBRT beams were obtained. Mean target position, time‐weighted standard deviation, and amplitude for these images as well as target motion for three SBRT lung patients were compared to respective pretreatment 4D CBCTs. Evaluation of intrafraction 4D CBCT reconstruction revealed inclusion of MV only images acquired to remove MV scatter effects. A workaround to remove these images was developed.ResultsAcquisitionInterval of 0.1°/frame was optimal. The number of kV frames acquired was 567–1116 and showed strong linear correlation with beam monitor unit (MUs). Phantom target motion accuracy was excellent with average differences in target position, standard deviation and amplitude range of ≤0.5 mm. Target tracking for SBRT patients also showed good agreement. Evaluation of phase sorting wave forms showed that inclusion of MV only images significantly impacts intrafraction image reconstruction for patients and use of workaround is necessary.ConclusionsA universal intrafraction imaging preset can be used safely for SBRT lung patients. The number of kV projections with MV delivery parameters varies; however images with fewer kV projections still provided accurate target position information. Impact of the reconstruction workaround was significant and is mandated for all 4D CBCT intrafraction imaging performed at our institution.

Method for four‐channel monopulse radar to resist dual‐source angle deception jamming

Towed decoy can simulate the time domain and frequency domain characteristics of target in radar beam and form effective angle deception. In order to improve the radar ability to countermeasure towed decoy, this study extracts and uses the radar diagonal difference channel in the conventional monopulse radar. The characteristic of diagonal difference channel is analysed. Then, the equations of sum channel, azimuth difference channel, elevation difference channel, and diagonal difference channel are established. By solving the equations, the angles and amplitude of decoy and target are obtained. Decoy recognition method is proposed. The new method can obtain the angles of decoy and target using only one pulse, and recognise decoy steadily using several pulses. The simulation results confirm the effectiveness of the new method.

Two-Dimensional Analysis of Smooth Pursuit Eye Movements Reveals Quantitative Deficits in Precision and Accuracy.

PurposeSmall moving targets are followed by pursuit eye movements, with success ubiquitously defined by gain. Gain quantifies accuracy, rather than precision, and only for eye movements along the target trajectory. Analogous to previous studies of fixation, we analyzed pursuit performance in two dimensions as a function of target direction, velocity, and amplitude. As a subsidiary experiment, we compared pursuit performance against that of fixation.MethodsEye position was recorded from 15 observers during pursuit. The target was a 0.4° dot that moved across a large screen at 8°/s or 16°/s, either horizontally or vertically, through peak-to-peak amplitudes of 8°, 16°, or 32°. Two-dimensional eye velocity was expressed relative to the target, and a bivariate probability density function computed to obtain accuracy and precision. As a comparison, identical metrics were derived from fixation data.ResultsFor all target directions, eye velocity was less precise along the target trajectory. Eye velocities orthogonal to the target trajectory were more accurate during vertical pursuit than horizontal. Pursuit accuracy and precision along and orthogonal to the target trajectory decreased at the higher target velocity. Accuracy along the target trajectory decreased with smaller target amplitudes.ConclusionsOrthogonal to the target trajectory, pursuit was inaccurate and imprecise. Compared to fixation, pursuit was less precise and less accurate even when following the stimulus that gave the best performance.Translational RelevanceThis analytical approach may help the detection of subtle deficits in slow phase eye movements that could be used as biomarkers for disease progression and/or treatment.

Effects of Target Amplitude Uncertainty, Background Contrast Uncertainty, and Prior Probability Are Predicted by the Normalized Template-Matching Observer

Effects of Target Amplitude Uncertainty, Background Contrast Uncertainty, and Prior Probability Are Predicted by the Normalized Template-Matching Observer

Application of RADAR Imaging Analysis to SuperDARN Observations

AbstractRecently, Universal Software Radio Peripherals were installed at the McMurdo, Antartica, and Kodiak, Alaska, Super Dual Auroral Radar Network (SuperDARN) radars to replace existing synthesizer and receiver electronics. Each antenna in the radar arrays was connected to its own Universal Software Radio Peripherals input, which enables controlling the phase of the transmitted signal and sampling the received signals on each antenna. Received data are written to disk and simultaneously combined using beam forming to produce the standard SuperDARN data stream. The raw signal data from the individual antennas is retrieved from the radar sites and analyzed using an algorithm that fits a model signal based on the assumption of individual plane waves arriving from discrete angle bins in the field of view. With this analysis the target amplitudes and Doppler frequencies can be determined as a function of angle. In this paper, the theory behind the algorithm is developed, and synthetic test data are presented, as are real observations. Finally, the line‐of‐sight velocities determined from the data are used to estimate maps of the vector velocity field that produced them.

Emulating the Statistical Properties of Indoor Power Line Colored Background Noise for Development of a Power Line Noise Simulator

This paper deals with the development of a realistic power line channel simulator wherein power line communication devices can be tested before implementation to meet the massive need of data transfer. The statistics of the noise follow the experimentally observed in different sites, namely the time-varying non-white power spectral densities (PSDs) of the background noise and a target non Gaussian amplitude distribution. The procedure based on the inverse cumulative distribution function method of generation of random numbers and iteratively updating a target spectrum necessitates knowledge of a maximum of 17 parameters for successful implementation and has been validated for three sites in the low-frequency ([Formula: see text]500[Formula: see text]kHz) and high-frequency (1–30[Formula: see text]MHz) bands. The average percentage errors in prediction of the mean of the channel capacity (CC) are 12.68% and 10.66% in the two bands, respectively. The minimum correlations of the distribution of BER of OFDM in a channel corrupted by the simulated and observed noises are is 0.883 and 0.801 in the two bands which are high compared to 0.422 and 0.355, respectively, when the requirement of a target amplitude distribution is neglected. With low-frequency noise emulated by a data acquisition card, an average percentage error of 11.82% in the CC and a correlation of 0.867 (against 0.498) in BER are obtained. The noise thus generated can be used as a testbed for system testing, instead of the conventional static models (additive white Gaussian noise or with time-invariant colored PSD), leading to better optimization of the implemented devices.

Balance with the interactive size effects of display, target, and key spacing in tablet tapping, dragging, and typing tasks

AbstractThis study aimed to expand the current demonstration of display size effects from pointing tasks to dragging and tap‐typing tasks to investigate the effects of influential factors on the performance of touchscreen tablets. From 7‐ to 11‐in. displays, the index of difficulty was kept constant by increasing the target amplitudes and widths (6.0–9.5 mm) proportionally, and the key spacing were, respectively, 13.5 × 7.3–21.5 × 11.5 mm with 0‐mm key gaps. The results demonstrated that simple task types (complexities) reinforced the display size effects and that the effects interacted with target sizes (including amplitude/width scaling) and key spacing to reflect increasing efficiency and usability with increasing sizes. Gender effects were only significant in subjective assessments. Display sizes approaching 10 in., target sizes not less than 7 mm (optimal 9–10 mm) and key spacing larger than 17.5 mm induced the effects of motor scale (the scale of the upper limb joint coordination) and interacted with one another to result in the optimal performance and usability.

Investigating the Efficacy of the Hand Selection Complexity Task Across the Lifespan

There is inconsistent evidence demonstrating a relationship between task complexity and hand preference. However, analyzing the point at which task complexity overrides the decision to demonstrate a biomechanically efficient movement can enable complexity to be quantified. Young children (ages 3–7), adolescents (ages 8–12), young adults (ages 18–25), and older adults (ages 65+) performed a newly developed Hand Selection Complexity Task (HSCT) and completed the Waterloo Handedness Questionnaire (WHQ). The HSCT included a reciprocal Fitts’ tapping task performed in the contralateral space (i.e., same side as preferred hand), followed by ipsilateral space (i.e., opposite side of preferred hand). An alternating contralateral-ipsilateral pattern enabled the participant to progress through six levels of difficulty in three conditions (manipulating target amplitude, width, and combined factors). As participants were free to perform with whichever hand (i.e., preferred, non-preferred) they deemed most appropriate, the level of difficulty where a hand switch occurred was identified. HSCT completion time and error scores were also computed. Findings revealed age to be a significant predictor of dependent measures when considering significant effects and interactions. Combined with the covariate WHQ score as a significant predictor of HSCT time and errors (in some, but not all cases), it can be argued that age-related effects reflect the development of handedness, and changes in strength of handedness across the lifespan. Together, findings suggest that task complexity plays an important role in hand selection when performing a task of increasing difficulty. It appears that task complexity will take precedent over object proximity and biomechanical efficiency, at a certain point, in order to complete the movement with the preferred hand. This point ultimately changes throughout the lifespan.

Optimization of diffractive optical elements with millions of pixels using progressive error reduction algorithm (PERA)

Spatial light modulators (SLMs) comprising millions of micro-pixels have been applied for advanced applications requiring diffractive images of high quality (i.e., low root-mean-squared error, high signal-to-noise ratio, and low signal variation). Diffractive optical elements (DOEs) to be displayed in high-resolution SLMs are calculated using optimization algorithms to produce specific images. Current DOE optimization algorithms are incapable of providing high-quality images or else they consume too much time doing so. This paper presents two algorithms: the large error reduction algorithm (LERA) and the progressive error reduction algorithm (PERA). LERA selects image pixels (px) with the largest error for replacement with a target amplitude to improve image quality beyond what could be achieved using the iterative Fourier transform algorithm (IFTA). LERA tends to be time-consuming; however, it is able to reduce variations in signal intensity to 1.73e-8. PERA accelerates the optimization process by cascading an IFTA and several modified LERAs. Experiments were conducted on six DOEs of 1920×1080 px using a three-stage PERA equipped with three scaling factors.

Target Motion Parameters Estimation in Forward Scatter Radar

This paper is devoted to the estimation of target motion parameters with a forward scatter radar (FSR). To provide an upper bound for the estimation performance, a closed-form expression of the Cramer–Rao lower bound (CRLB) is provided for the main target signal parameters, namely Doppler rate, baseline crossing instant, and main lobe width parameter of the target amplitude modulation pattern. This is performed by operating on the signal at the output of the standard FSR processing scheme, namely on the crystal video detector signal: the received signal, which is passed through a square-law envelope detector followed by a DC removal filter. The estimate of the kinematic parameters of moving targets that follow a linear trajectory can be obtained by inverting the relationship between these parameters and the previously estimated target signal parameters. Especially, two FSR configurations are investigated: single-node FSR configuration and dual-baseline FSR configuration with a small angular separation between the two baselines. The closed-form expression of the corresponding CRLB is derived by using a linearized version of the same inverse transformation. Finally, a practical estimator is presented, based on a two-dimensional filter bank, and its performance is compared with the derived CRLB. The results show that unbiased and highly accurate estimates of the kinematic parameters are obtained. The feasibility and the effectiveness of this estimation scheme is demonstrated by applying this technique to recorded live data acquired with a dual-baseline FSR configuration exploiting FM signals as a waveform of opportunity.

Voluntary Saccade Training Protocol in Persons With Parkinson's Disease and Healthy Adults.

Background: Voluntary saccade function gradually decreases during both the progression of Parkinson’s disease (PD) and neurologically healthy adult aging. Voluntary saccades display decreased length and increased saccade latency, duration, and the number of compensatory saccades in aging and PD. Saccades serve as the key eye movement for maintaining salient features of the visual environment on the high visual acuity fovea of the retina. Abnormal saccade behavior has been associated with freezing of gait in PD. We have not identified any studies that have investigated improvement in voluntary saccade function using voluntary saccade training.Objective: We report an experimental protocol that tests a training paradigm following the principle of specificity to improve voluntary saccade velocity and amplitude, while decreasing latency and the number of compensatory saccades.Methods: Persons with PD (n = 22) and persons with no known neurological disorders (n = 22) between the ages of 40 and 65 years will be recruited. In a randomized-block study design, all participants will perform voluntary saccades to targets in eight cardinal and intercardinal directions. In each of the eight sessions during the four-week intervention period, participants will train at three target amplitudes. Participants will perform 40 trials for each amplitude block, consisting of five randomly presented repetitions for each direction. Voluntary and reflexive saccades will be recorded pre- and post-intervention, along with clinical mobility assessment using the Movement Disorder Society Unified Parkinson’s Disease Rating Scale. Mobility scores, the amplitude, latency, and duration of the first saccade, and the number of saccades to reach the fixation target will be analyzed using an ANOVA of mixed effects.Discussion: This protocol holds promise as a potential method to improve voluntary saccade function in persons with PD. Should persons with PD not improve on any outcome following the intervention, this lack of response may support the use of saccade assessment as a response biomarker for the diagnosis of PD.Trial Registration: This protocol was retrospectively registered at ISRCTN (ISRCTN.com) since July 25, 2018. The first participant was recruited March 12, 2016. The protocol identifier is 17784042.Descriptive Title: A two-arm, pre/post-protocol to compare the effects of a four-week voluntary saccade training intervention in persons with Parkinson’s disease and healthy adults aged forty years or older.

Unambiguous Sparse Recovery of Migrating Targets With a Robustified Bayesian Model

The problem considered is that of estimating unambiguously migrating targets observed with a wideband radar. We extend a previously described sparse Bayesian algorithm to the presence of diffuse clutter and off-grid targets. A hybrid-Gibbs sampler is formulated to jointly estimate the sparse target amplitude vector, the grid mismatch, and the (assumed) autoregressive noise. Results on synthetic and fully experimental data show that targets can be actually unambiguously estimated even if located in blind speeds.

Hand function, not proximity, biases visuotactile integration later in object processing: An ERP study.

Behavioral studies document a functional hand proximity effect: objects near the palm, but not the back of the hand, affect visual processing. Although visuotactile bimodal neurons integrate visual and haptic inputs, their receptive fields in monkey cortex encompass the whole hand, not just the palm. Using ERPs, we investigated whether hand function influenced the topology of integrated space around the hand. In a visual detection paradigm, target and non-target stimuli appeared equidistantly in front or in back of the hand. Equivalent N1 amplitudes were found for both conditions. P3 target versus non-target amplitude differences were greater for palm conditions. Hand proximity biased processing of visual targets equidistant from the hand early in processing. However, hand function biases emerged later when targets were selected for potential action. Thus, early hand proximity effects on object processing depend on sensory-reliant neural responses, whereas later multisensory integration depend more on the hand's functional expertise.

SU139GENOME-WIDE ASSOCIATION ANALYSIS OF LIFETIME CANNABIS USE (N=184,765) IDENTIFIES NEW RISK LOCI, GENETIC OVERLAP WITH MENTAL HEALTH, AND A CAUSAL INFLUENCE OF SCHIZOPHRENIA ON CANNABIS USE

The motor system’s natural tendency is to move the limbs over equal amplitudes, for example in walking. However, in many situations in which people must perform complex movements, a certain degree of amplitude differentiation of the limbs is required. Visual and haptic feedback have recently been shown to facilitate such independence of limb movements. However, it is unknown whether motor expertise moderates the extent to which individuals are able to differentiate the amplitudes of their limb-movements while being supported with visual and haptic feedback. To answer this question 14 pre-professional dancers were compared to 14 non-dancers on simultaneously generating a small displacement with one foot, and a larger one with the other foot, in four different feedback conditions. In two conditions, haptic guidance was offered, either in a passive or active mode. In the other two conditions, veridical and enhanced visual feedback were provided. Surprisingly, no group differences were found regarding the degree to which the visual or haptic feedback assisted the generation of the different target amplitudes of the feet (mean amplitude difference between the feet). The correlation between the displacements of the feet and the standard deviation of the continuous relative phase between the feet, reflecting the degree of independence of the feet movements, also failed to show between-group differences. Sample entropy measures, indicating the predictability of the foot movements, did show a group difference. In the haptically-assisted conditions, the dancers demonstrated more predictable coordination patterns than the non-dancers as reflected by lower sample entropy values whereas the reverse was true in the visual-feedback conditions. The results demonstrate that motor expertise does not moderate the extent to which haptic tracking facilitates the differentiation of the amplitudes of the lower limb movements in an asymmetrical bipedal coordination task.

P55. Probing homeostatic and metaplastic mechanisms of quadri-pulse theta burst stimulation using an inhibitory priming protocol

Question Changes in synaptic and neuronal efficacy such as long-term potentiation (LTP) and long-term depression (LTD) are thought to reflect synaptic processes underlying learning and memory. Homeostatic plasticity is considered to stabilize neural activity within a physiologically reasonable and dynamic range. Quadri-pulse-thetaburst stimulation (qTBS) is a recently introduced patterned transcranial magnetic stimulation (TMS) protocol that induced lasting increase or decrease in neuronal excitability of human primary motor cortex (M1) probably corresponding to the model of LTP- and LTD-like plasticity. Here, we aimed to probe homeostatic and metaplastic interactions of an inhibitory priming qTBS protocol on subsequent facilitating and inhibitory qTBS. Methods We investigated the priming mechanisms of inhibitory qTBS on subsequent facilitating qTBS (experiment 1) in 8 healthy volunteers and on subsequent inhibitory qTBS (experiment 2) in 9 healthy volunteers. Inhibitory qTBS consisted of 360 bursts given continuously to M1 (i.e. 1440 full-sine pulses) with bursts of four biphasic TMS pulses (duration 160 μ s) separated by inter-stimulus intervals (ISI) of 50 ms (20 Hz) and inter-burst intervals of 200 ms (5 Hz) (qTBS50/200). Facilitatory qTBS consisted of the same burst pattern but with ISI of 5 ms (200 Hz) (qTBS5/200). TMS was applied by a custom-made magnet stimulator (MSB, Munich). Resting motor threshold (RMT) and motor evoked potential (MEP) amplitudes with stimulus intensities to target amplitudes of 1 mV were measured before priming qTBS50/200 (pre), directly after priming qTBS50/200 (post1), after 15 min (post2) and after 30 min (post3). Following post 3 measurements, the second stimulation (qTBS5/200 or qTBS50/200) was applied and the RMT and MEP were measured for 60 min (post4–post7). Results In experiment 1 (qTBS50/200–qTBS5/200), priming with qTBS50/200 led to a decrease of MEP amplitudes (post1–3), while MEP amplitudes increased following subsequent qTBS5/200 (post 4–7). Mean changes of post 4–7 increased significantly as compared to mean changes of post 1–3. In experiment 2 (qTBS50/200–qTBS50/200), MEP amplitudes decreased following the priming protocol (post 1–3) and returned to baseline with a slight increase on post 6 after the subsequent qTBS50/200 protocol. Mean changes of post 4–7 increased significantly as compared to mean changes of post 1–3. Conclusion Our preliminary results may point towards homeostatic mechanisms of facilitatory qTBS5/200 following priming with qTBS50/200. In contrast, subsequent qTBS50/200 led to a de-depression like effect of MEP amplitudes suggesting metaplastic effects of two inhibitory qTBS protocols applied over M1. Our findings may support the assumption that changes in cortico-spinal excitability following qTBS represent LTP- and LTD-like changes in synaptic transmission and corroborate metaplastic de-depression effects of high-frequency patterned rTMS protocols in human M1.

Electrostatically actuated encased cantilevers.

Background: Encased cantilevers are novel force sensors that overcome major limitations of liquid scanning probe microscopy. By trapping air inside an encasement around the cantilever, they provide low damping and maintain high resonance frequencies for exquisitely low tip–sample interaction forces even when immersed in a viscous fluid. Quantitative measurements of stiffness, energy dissipation and tip–sample interactions using dynamic force sensors remain challenging due to spurious resonances of the system.Results: We demonstrate for the first time electrostatic actuation with a built-in electrode. Solely actuating the cantilever results in a frequency response free of spurious peaks. We analyze static, harmonic, and sub-harmonic actuation modes. Sub-harmonic mode results in stable amplitudes unaffected by potential offsets or fluctuations of the electrical surface potential. We present a simple plate capacitor model to describe the electrostatic actuation. The predicted deflection and amplitudes match experimental results within a few percent. Consequently, target amplitudes can be set by the drive voltage without requiring calibration of optical lever sensitivity. Furthermore, the excitation bandwidth outperforms most other excitation methods.Conclusion: Compatible with any instrument using optical beam deflection detection electrostatic actuation in encased cantilevers combines ultra-low force noise with clean and stable excitation well-suited for quantitative measurements in liquid, compatible with air, or vacuum environments.

Feeling but not seeing the hand: Occluded hand position reduces the hand proximity effect in ERPs.

The hand proximity effect (nearby hands influence visual processing) reflects the integration of vision and proprioception for upcoming action; it is reduced when hand position is occluded. In an ERP study, we investigate whether hand proximity, without vision of the hand, accentuates the processing of stimuli requiring actions (targets) early (N1) and later (P3) in processing. In a go/no-go paradigm, participants viewed stimuli between two panels with hands placed near or far from stimuli. Occlusion of the hand eliminated near-hand target vs. non-target differentiation of the N1; amplification of near-hand target amplitudes emerged at the P3. Visual hand location appears necessary to draw visual attention to intended-action objects to integrate body and visual information early in processing. The integration of visual stimulus information and hand position from proprioception appears later in processing, indicating greater reliance on cognitive systems for discriminating the task-relevance of a stimulus.