High Frequency Patterns Research Articles

STRUCTURED LIGHT BASED 3D SCANNING FOR SPECULAR SURFACE BY THE COMBINATION OF GRAY CODE AND PHASE SHIFTING

Surface reconstruction using coded structured light is considered one of the most reliable techniques for high-quality 3D scanning. With a calibrated projector-camera stereo system, a light pattern is projected onto the scene and imaged by the camera. Correspondences between projected and recovered patterns are computed in the decoding process, which is used to generate 3D point cloud of the surface. However, the indirect illumination effects on the surface, such as subsurface scattering and interreflections, will raise the difficulties in reconstruction. In this paper, we apply maximum min-SW gray code to reduce the indirect illumination effects of the specular surface. We also analysis the errors when comparing the maximum min-SW gray code and the conventional gray code, which justifies that the maximum min-SW gray code has significant superiority to reduce the indirect illumination effects. To achieve sub-pixel accuracy, we project high frequency sinusoidal patterns onto the scene simultaneously. But for specular surface, the high frequency patterns are susceptible to decoding errors. Incorrect decoding of high frequency patterns will result in a loss of depth resolution. Our method to resolve this problem is combining the low frequency maximum min-SW gray code and the high frequency phase shifting code, which achieves dense 3D reconstruction for specular surface. Our contributions include: (i) A complete setup of the structured light based 3D scanning system; (ii) A novel combination technique of the maximum min-SW gray code and phase shifting code. First, phase shifting decoding with sub-pixel accuracy. Then, the maximum min-SW gray code is used to resolve the ambiguity resolution. According to the experimental results and data analysis, our structured light based 3D scanning system enables high quality dense reconstruction of scenes with a small number of images. Qualitative and quantitative comparisons are performed to extract the advantages of our new combined coding method.

STRUCTURED LIGHT BASED 3D SCANNING FOR SPECULAR SURFACE BY THE COMBINATION OF GRAY CODE AND PHASE SHIFTING

Abstract. Surface reconstruction using coded structured light is considered one of the most reliable techniques for high-quality 3D scanning. With a calibrated projector-camera stereo system, a light pattern is projected onto the scene and imaged by the camera. Correspondences between projected and recovered patterns are computed in the decoding process, which is used to generate 3D point cloud of the surface. However, the indirect illumination effects on the surface, such as subsurface scattering and interreflections, will raise the difficulties in reconstruction. In this paper, we apply maximum min-SW gray code to reduce the indirect illumination effects of the specular surface. We also analysis the errors when comparing the maximum min-SW gray code and the conventional gray code, which justifies that the maximum min-SW gray code has significant superiority to reduce the indirect illumination effects. To achieve sub-pixel accuracy, we project high frequency sinusoidal patterns onto the scene simultaneously. But for specular surface, the high frequency patterns are susceptible to decoding errors. Incorrect decoding of high frequency patterns will result in a loss of depth resolution. Our method to resolve this problem is combining the low frequency maximum min-SW gray code and the high frequency phase shifting code, which achieves dense 3D reconstruction for specular surface. Our contributions include: (i) A complete setup of the structured light based 3D scanning system; (ii) A novel combination technique of the maximum min-SW gray code and phase shifting code. First, phase shifting decoding with sub-pixel accuracy. Then, the maximum min-SW gray code is used to resolve the ambiguity resolution. According to the experimental results and data analysis, our structured light based 3D scanning system enables high quality dense reconstruction of scenes with a small number of images. Qualitative and quantitative comparisons are performed to extract the advantages of our new combined coding method.

Wavelet Transform Data Compression with an Error Level Guarantee for Z-Map Models

This paper proposes an algorithm to compress CAD models in a grid-based Z-map representation while keeping the compression artifacts within a specified value (the maximum difference allowed by the user). A wavelet transform is used for decomposing the input shape into lower and higher frequency patterns. A significant reduction in the data size can be achieved by deleting higher frequency components. We employ a tree structure called the error range (ER) tree to manage error occurrences and determine where to prune branches without increasing the resulting errors in the data compression. The widely used reversible compression method, gzip, is then used to obtain the final compressed model data output. We conducted a series of experiments with 12 sample shape models on a 512 × 512 grid. With a maximum error of 10 μm (a typical value specified for NC milling), the proposed method reduces the data by 90.9% on average and the computational cost of 19 ms is extremely low. The proposed method can be extended to larger CAD models in real applications.

Mutational analysis of MED12 exon 2 in a spectrum of fibroepithelial tumours of the breast: implications for pathogenesis and histogenesis.

Fibroadenomas (FAs) and phyllodes tumours (PTs) are fibroepithelial tumours. Mutations in MED12 exon 2 have been reported in FAs. This study investigated the MED12 mutations in a spectrum of fibroepithelial tumours. Using direct sequencing, we analysed MED12 exon 2 mutations on 121 samples, including PTs and FAs and variants. We found MED12 mutations in 71.4% of PTs. No significant difference in the mutation frequency was observed between benign, borderline and malignant PTs, and a general lack of correlation existed between mutations and pathological factors associated with PT grading. The mutation patterns were similar between PTs and FAs, with codon 44 being involved most frequently. MED12 mutations were identified in 47.1, 52.6 and 50.0% of complex FAs, juvenile FAs and tubular adenomas (TAs), respectively, and the frequency and mutation patterns were similar between these FA variants and usual FAs. The high frequency and similar patterns of MED12 mutations in FAs and various grades of PTs implies that the MED12 mutation is a common and early pathological event in these fibroepithelial tumours. The similar frequency and patterns of the MED12 mutation between FAs and variants suggests that FA variants are bona fide FAs, with identical pathogenesis involving MED12 mutations.

Measurement of the radiation patterns of navy shipboard High Frequency (HF) antennas on a large warship

Warships use strategic and tactical communications to be connected with national command headquarters and other units around the world. Therefore vessels need a communication system to be able to provide line-of-sight and long-haul communications. High Frequency (HF) communications can meet this requirement. Thus the ship needs to know the behavior of HF communications systems, for example, if they have any null in the radiation pattern. This article describes the measurements of the radiation patterns of HF whips in different places and with different polarizations (2–30MHz) on a large vessel. Theoretically, HF shipboard antennas are close to be omnidirectional, so that the transmission and reception do not depend on where the ship is heading. We need to know the patterns at different frequencies first, to evaluate if the place where the antennas have been placed is adequate and second, to detect the possible nulls in the radiation pattern.

Visual choice behavior by bumblebees (Bombus impatiens) confirms unsupervised neural network's predictions.

The behavioral experiment herein tests the computational load hypothesis generated by an unsupervised neural network to examine bumblebee (Bombus impatiens) behavior at 2 visual properties: spatial frequency and symmetry. Untrained "flower-naïve" bumblebees were hypothesized to prefer symmetry only when the spatial frequency of artificial flowers is high and therefore places great information-processing demands on the bumblebees' visual system. Bumblebee choice behavior was recorded using high-definition motion-sensitive camcorders. The results support the computational model's prediction: 1-axis symmetry influenced bumblebees' preference behavior at low and high spatial frequency patterns. Additionally, increasing the level of symmetry from 1 axis to 4 axes amplified preference toward the symmetric patterns of both low and high spatial frequency patterns. The results are discussed in the context of the artificial neural network model and other hypotheses generated from the behavioral literature.

Quantitative analysis of wrist electrodermal activity during sleep

We present the first quantitative characterization of electrodermal activity (EDA) patterns on the wrists of healthy adults during sleep using dry electrodes. We compare the new results on the wrist to the prior findings on palmar or finger EDA by characterizing data measured from 80 nights of sleep consisting of 9 nights of wrist and palm EDA from 9 healthy adults sleeping at home, 56 nights of wrist and palm EDA from one healthy adult sleeping at home, and 15 nights of wrist EDA from 15 healthy adults in a sleep laboratory, with the latter compared to concurrent polysomnography. While high frequency patterns of EDA called “storms” were identified by eye in the 1960s, we systematically compare thresholds for automatically detecting EDA peaks and establish criteria for EDA storms. We found that more than 80% of the EDA peaks occurred in non-REM sleep, specifically during slow-wave sleep (SWS) and non-REM stage 2 sleep (NREM2). Also, EDA amplitude is higher in SWS than in other sleep stages. Longer EDA storms were more likely to occur in the first two quarters of sleep and during SWS and NREM2. We also found from the home studies (65 nights) that EDA levels were higher and the skin conductance peaks were larger and more frequent when measured on the wrist than when measured on the palm. These EDA high frequency peaks and high amplitude were sometimes associated with higher skin temperature, but more work is needed looking at neurological and other EDA elicitors in order to elucidate their complete behavior.

Sub-diffusive scattering parameter maps recovered using wide-field high-frequency structured light imaging.

This study investigates the hypothesis that structured light reflectance imaging with high spatial frequency patterns [Formula: see text] can be used to quantitatively map the anisotropic scattering phase function distribution [Formula: see text] in turbid media. Monte Carlo simulations were used in part to establish a semi-empirical model of demodulated reflectance ([Formula: see text]) in terms of dimensionless scattering [Formula: see text] and [Formula: see text], a metric of the first two moments of the [Formula: see text] distribution. Experiments completed in tissue-simulating phantoms showed that simultaneous analysis of [Formula: see text] spectra sampled at multiple [Formula: see text] in the frequency range [0.05-0.5] [Formula: see text] allowed accurate estimation of both [Formula: see text] in the relevant tissue range [0.4-1.8] [Formula: see text], and [Formula: see text] in the range [1.4-1.75]. Pilot measurements of a healthy volunteer exhibited [Formula: see text]-based contrast between scar tissue and surrounding normal skin, which was not as apparent in wide field diffuse imaging. These results represent the first wide-field maps to quantify sub-diffuse scattering parameters, which are sensitive to sub-microscopic tissue structures and composition, and therefore, offer potential for fast diagnostic imaging of ultrastructure on a size scale that is relevant to surgical applications.

Binge alcohol consumption in emerging adults: anterior cingulate cortical "thinness" is associated with alcohol use patterns.

The brain undergoes dynamic and requisite changes into the early 20s that are associated with improved cognitive efficiency, particularly in prefrontal regions that are still undergoing neuromaturation. As alcohol consumption is typically initiated and progresses to binge drinking (BD) during this time, the objective of the present study was to investigate the impact of binge alcohol consumption on frontal lobe cortical thickness in emerging adults. Twenty-three binge drinking (11 females, mean age 22.0 ± 1.2) and 31 light drinking (15 females, mean age 21.5 ± 1.6) emerging adults underwent high-resolution magnetic resonance imaging at 3 Tesla. Cortical surface reconstruction and thickness estimation were performed using FreeSurfer for 3 a priori brain regions of interest: bilateral anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), and parieto-occipital sulcus (POS). Cortical thickness measurements were then compared between binge drinker (BD) and light drinker (LD) groups. Cortical thickness was significantly lower in BD than LD in the right middle ACC (mid-ACC; p ≤ 0.05) and in the left dorsal PCC (dPCC; p ≤ 0.01). No significant differences in cortical thickness were observed in the POS. Cortical thickness in the mid-ACC correlated negatively with higher quantity and frequency of drinks consumed (p < 0.01) and positively with the number of days elapsed since most recent use (p < 0.05). Furthermore, less cortical thickness in the mid-ACC in the BD group alone correlated with reported patterns of high quantity and frequency of alcohol consumption (p ≤ 0.05). Findings suggest that past and recent patterns of intermittent heavy alcohol consumption are associated with less frontal cortical thickness (i.e., "thinness") of the right mid-ACC and left dPCC in emerging adults, but not the POS. While cortical thinness could have predated binge drinking, this pattern of maladaptive consumption may have acute neurotoxic effects that interfere with the finalization of neuromaturational processes in the vulnerable frontal cortex, resulting in increased microarchitectural pruning.

An algorithm based on traveling waves for transmission line protection in a TCSC environment

This paper describes a new relaying algorithm for the protection of transmission lines with a Thyristor Controlled Series Compensator (TCSC). The algorithm is based on the pattern of traveling waves generated during a fault event. Several tools like modal analysis, the discrete wavelet transform and a probabilistic neural network trained to work with the energy contained in the wavelet transform coefficients are applied to analyze the high frequency pattern generated during the fault. The proposed algorithm is capable of detecting, locating and classifying faults in a reliable way. The impact of harmonic frequencies generated by the TCSC in the protection algorithm was also analyzed. Several studies were carried out in order to validate and to assess the effect of several fault parameters on the algorithm accuracy. The obtained results show that for a sampling rate of 100kHz, the algorithm error in calculating the distance to the fault is less than one percent of the total transmission line length. A higher sampling rate improves the algorithm accuracy.

Analyzing ECoG Distortions in Cochlear Implant Patients and Gerbils

Objectives: 1) Describe how rectification and saturation in hair cell and neural responses contribute to electrocorticography (ECoG) recordings in an animal model. 2) Analyze distortions in intraoperative recordings of cochlear implant patients. Methods: ECoG potentials from the round window (RW) of humans and gerbils were measured to tones of different frequencies and intensities. Human subjects receiving cochlear implants had a variable degree of hearing loss. The gerbils had normal hearing or a pattern of high frequency, noise-induced hearing loss similar to many cochlear implant recipients. In our animal model, forward masking, simultaneous masking, and application of a neurotoxin to the RW were used to isolate hair cell and neural responses. Results: In both humans and gerbils, discrete patterns of distortions in the ECoG waveform were present that had either a hair cell or neural origin. Distortions due to phase locking of nerve fibers (the ANN) were the main cause of distortion at low frequencies and up to moderate intensities, while distortions seen at high intensities across all frequencies suggested saturation of stereociliary movement in the CM. Conclusions: Distortions originating from phase locking in nerve fibers can be diminished with forward masking or a neurotoxin, helping to isolate the relative contribution of nerve fibers and hair cells. Distortions in the animal model are also present in ECoG recordings in cochlear implant patients, and can have hair cell or neural origins.

The effect of spatial smoothing on fMRI decoding of columnar-level organization with linear support vector machine

We examined how spatial smoothing affects the result of multivariate classification analysis using the linear support vector machine (SVM) for decoding columnar-level organization. It has been suggested that the effect of spatial smoothing on decoding performance is minor because smoothing operation is an invertible data transformation and such invertible transformation does not remove information in multivariate pattern. Our theoretical consideration, however, revealed that generalization score (performance for test samples unused during classifier training) was susceptible to non-uniform scaling of input data; SVM classifier became less sensitive to variability in shrunk dimension. This result indicates that spatial smoothing reduces sensitivity of SVM classifier to high spatial frequency pattern so that the effect of smoothing implies the amount of information distributed in spatial frequencies. We also examined the effect of smoothing in an fMRI experiment of decoding ocular dominance responses. The results of group statistic showed that large smoothing reduced decoding accuracies while the smoothing effect at individual subject were not the same for all subjects. These results suggest that spatial smoothing can have major effect on decoding performance and the informative pattern for columnar level decoding resides in higher frequencies on average across subjects while it may distribute multiple frequencies at individual subject level.

Orientation fields in shape from shading

The interaction of shape, material and lighting creates complex patterns of orientation in the image, which play an important role in 3D surface estimation. Depending on the nature of these orientation fields, different cues can be extracted: the orientation fields produced by textured objects carry information about the 3D orientation of the surface (i.e. first order properties), while shading is compressed and stretched depending on the second-order (curvature) properties of the shape. Here, we investigate the relation between shading flows and the perception of shape. We show that by locally modifying the orientations in images of shaded surfaces, we are able to substantially alter the perceived shape. We performed two experiments in which subjects had to match the perceived shape of a test stimulus. In the first experiment, stimuli were generated by adding high frequency patterns (HFPs) on top of diffuse shading. HFPs were oriented along the principal curvature directions of the surface, by 'smearing' noise using line integral convolution. Results show that, depending on the smearing intensity and on the chosen curvature direction (i.e., minimal or maximal), surface features appeared to be either sharpened or rounded respectively. In the second experiment, we used an image processing operator to control the behavior of low-frequencies (LF) shading orientations. By distorting LF gradient patterns on a surface according to curvature information, we are able to precisely control the orientation field in an image. We show that the more a feature is aligned with the shading orientation, the less subjects are able to perceive it correctly. These experiments show that there is a direct relationship between shading orientation flows and our perception of surface curvature, implying that image orientation measurements play a key role in the estimation of shape from shading.

군집분석과 상세기상모델을 통한 포항지역 계절별 바람장 특성

The typical characteristics of seasonal winds were studied around the Pohang using two-stage (average linkage then k-means) clustering technique based on u- and v-component wind at 850 hpa from 2004 to 2006 (obtained the Pohang station) and a high-resolution (0.5 km grid for the finest domain) WRF-UCM model along with an up-to-date detailed land use data during the most predominant pattern in each season. The clustering analysis identified statistically distinct wind patterns (7, 4, 5, and 3 clusters) representing each spring, summer, fall, and winter. During the spring, the prevailed pattern (80 days) showed weak upper northwesterly flow and late sea-breeze. Especially at night, land-breeze developed along the shoreline was converged around Yeongil Bay. The representative pattern (92 days) in summer was weak upper southerly flow and intensified sea-breeze combined with sea surface wind. In addition, convergence zone between the large scale background flow and well-developed land-breeze was transported around inland (industrial and residential areas). The predominant wind distribution (94 days) in fall was similar to that of spring showing weak upper-level flow and distinct sea-land breeze circulation. On the other hand, the wind pattern (117 days) of high frequency in winter showed upper northwesterly and surface westerly flows, which was no change in daily wind direction.

Dissociated wake-like and sleep-like electro-cortical activity during sleep

Sleep is traditionally considered a global process involving the whole brain. However, recent studies have shown that sleep depth is not evenly distributed within the brain. Sleep disorders, such as sleepwalking, also suggest that EEG features of sleep and wakefulness might be simultaneously present in different cerebral regions. In order to probe the coexistence of dissociated (wake-like and sleep-like) electrophysiological behaviors within the sleeping brain, we analyzed intracerebral electroencephalographic activity drawn from sleep recordings of five patients with pharmacoresistant focal epilepsy without sleep disturbances, who underwent pre-surgical intracerebral electroencephalographic investigation. We applied spectral and wavelet transform analysis techniques to electroencephalographic data recorded from scalp and intracerebral electrodes localized within the Motor cortex (Mc) and the dorso-lateral Prefrontal cortex (dlPFc). The Mc showed frequent Local Activations (lasting from 5 to more than 60s) characterized by an abrupt interruption of the sleep electroencephalographic slow waves pattern and by the appearance of a wake-like electroencephalographic high frequency pattern (alpha and/or beta rhythm). Local activations in the Mc were paralleled by a deepening of sleep in other regions, as expressed by the concomitant increase of slow waves in the dlPFc and scalp electroencephalographic recordings. These results suggest that human sleep can be characterized by the coexistence of wake-like and sleep-like electroencephalographic patterns in different cortical areas, supporting the hypothesis that unusual phenomena, such as NREM parasomnias, could result from an imbalance of these two states.

P300 ERP Component Depends on Both Spatial Frequency and Contrast

Contrast perception depends on not only the early visual responses, but also top-down modulations. We measured how does P300, a well-documented event-related potential (ERP) index for top-down influence, change with both spatial frequency and contrast. ERP were acquired from 10 participants, aged 18–50 years, when they were performing a visual oddball task. The target was a Gabor patch whose spatial frequency was either 4 or 8 cy/degree and contrasts 90% or 30%. The probability of target presence in a trial was 30%. All target stimuli produced a reliable P300 component. At the low spatial frequency, the amplitude of P300 was larger and the latency was shorter for the low contrast patterns than for the higher contrast ones for all electrodes. Such difference was not observed in high spatial frequency patterns. The latency was slightly longer for high spatial frequency patterns than the low spatial frequency ones. Our results showed an interaction between spatial frequency and contrast in P300. The characteristics of P300 at low spatial frequency correlated with task difficulty, but not at high spatial frequency. This suggests that the top-down influence on contrast perception may be spatial frequency depended.

La stimulation magnétique transcrânienne (SMT) dans la recherche fondamentale et clinique en neuroscience

Non-invasive brain stimulation methods such as transcranial magnetic stimulation (TMS) are starting to be widely used to make causality-based inferences about brain-behavior interactions. Moreover, TMS-based clinical applications are under development to treat specific neurological or psychiatric conditions, such as depression, dystonia, pain, tinnitus and the sequels of stroke, among others. TMS works by inducing non-invasively electric currents in localized cortical regions thus modulating their activity levels according to settings, such as frequency, number of pulses, train and regime duration and intertrain intervals. For instance, it is known for the motor cortex that low frequency or continuous patterns of TMS pulses tend to depress local activity whereas high frequency and discontinuous TMS patterns tend to enhance it. Additionally, local cortical effects of TMS can result in dramatic patterns in distant brain regions. These distant effects are mediated via anatomical connectivity in a magnitude that depends on the efficiency and sign of such connections. An efficient use of TMS in both fields requires however, a deep understanding of its operational principles, its risks, its potential and limitations. In this article, we will briefly present the principles through which non-invasive brain stimulation methods, and in particular TMS, operate. Readers will be provided with fundamental information needed to critically discuss TMS studies and design hypothesis-driven TMS applications for cognitive and clinical neuroscience research.

The neural basis of color binding to an attended object

Event Abstract Back to Event The neural basis of color binding to an attended object Steven Hillyard1* 1 University of California at San Diego, United States Previous studies using ERPs and MEG have shown that attending to a moving dot surface produces a rapid activation of irrelevant features belonging to that surface. The co-activation of relevant and irrelevant features has been proposed as a neural mechanism for binding features together into a unified percept of the surface (object). In further studies we have recorded ERPs to determine whether an irrelevant color feature is activated when attention is directed to different types of objects and perceptual groupings. In separate experiments ERP components in the 200-300 ms range were identified that reflected activation of an irrelevant color when attention was directed to oriented arrays of lines, to check patterns of high or low spatial frequency, and to overlapping rectangular or oval shapes. We conclude that irrelevant feature activation occurs over a broad range of perceptual objects and may constitute a general mechanism for feature binding. Keywords: color binding, selective attention Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Symposium: Oral Presentation Topic: Symposium 1: Neural mechanisms of feature integration in object perception Citation: Hillyard S (2011). The neural basis of color binding to an attended object. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00012 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 03 Nov 2011; Published Online: 08 Nov 2011. * Correspondence: Dr. Steven Hillyard, University of California at San Diego, San Diego, United States, shillyard@ucsd.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Steven Hillyard Google Steven Hillyard Google Scholar Steven Hillyard PubMed Steven Hillyard Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Investigating the mechanisms that may underlie the reduction in contrast sensitivity during dynamic accommodation

Head and eye movements, together with ocular accommodation enable us to explore our visual environment. The stability of this environment is maintained during saccadic and vergence eye movements due to reduced contrast sensitivity to low spatial frequency information. Our recent work has revealed a new type of selective reduction of contrast sensitivity to high spatial frequency patterns during the fast phase of dynamic accommodation responses compared with steady-state accommodation. Here were report data which show a strong correlation between the effects of reduced contrast sensitivity during dynamic accommodation and velocity of accommodation responses, elicited by ramp changes in accommodative demand. The results were accounted for by a contrast gain control model of a cortical mechanism for contrast detection during dynamic ocular accommodation. Sensitivity, however, was not altered during attempted accommodation responses in the absence of crystalline-lens changes due to cycloplegia. These findings suggest that contrast sensitivity reduction during dynamic accommodation may be a consequence of cortical inhibition driven by proprioceptive-like signals originating within the ciliary muscle, rather than by corollary discharge signals elicited simultaneously with the motor command to the ciliary muscle.

Quarterly Estimates for Italy's Government Accrual Data

In this paper we calculate quarterly estimates for ten yearly budgetary items of the Conto Economico Consolidato della Pubblica Amministrazione (CECAP) published by ISTAT, covering the period from 1980 to 2007. The unknown high frequency pattern of fiscal variables is derived by the pattern observed of quarterly related series available in the CON-ISTAT database. We apply a dynamic extension of the Chow-Lin (1971) temporal disaggregation model, which is the method actually used by ISTAT for the estimation of quarterly national economic account data. As dealing with flow variables, the time constraint underlying the model imposes that the sum of quarterly estimates is equal to the yearly observation. The estimation strategy is based on the state space representation of a first order Autoregressive Distributed Lag model (Adl), which transforms the distribution problem into an unknown observation one. The choice of data assures that our quarterly estimates are fully comparable with quarterly government accrual data of major industrialized countries based on ESA95 and SNA93, both for institutional coverage, accountancy rules and definition of budgetary items.