1,575 research outputs found

    Generalized correlation measures of causality and forecasts of the VIX using non-linear models

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    This paper features an analysis of causal relations between the daily VIX, S & P500 and the daily realised volatility (RV) of the S & P500 sampled at 5 min intervals, plus the application of an Artificial Neural Network (ANN) model to forecast the future daily value of the VIX. Causal relations are analysed using the recently developed concept of general correlation Zheng et al. and Vinod. The neural network analysis is performed using the Group Method of Data Handling (GMDH) approach. The results suggest that causality runs from lagged daily RV and lagged continuously compounded daily return on the S & P500 index to the VIX. Sample tests suggest that an ANN model can successfully predict the daily VIX using lagged daily RV and lagged daily S & P500 Index continuously compounded returns as inputs

    Generalized correlation measures of causality and forecasts of the VIX using non-linear models

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    This paper features an analysis of causal relations between the daily VIX, S & P500 and the daily realised volatility (RV) of the S & P500 sampled at 5 min intervals, plus the application of an Artificial Neural Network (ANN) model to forecast the future daily value of the VIX. Causal relations are analysed using the recently developed concept of general correlation Zheng et al. and Vinod. The neural network analysis is performed using the Group Method of Data Handling (GMDH) approach. The results suggest that causality runs from lagged daily RV and lagged continuously compounded daily return on the S & P500 index to the VIX. Sample tests suggest that an ANN model can successfully predict the daily VIX using lagged daily RV and lagged daily S & P500 Index continuously compounded returns as inputs

    Pengaruh Sistem Pengendalian Intern Pemerintah, Kompetensi Sumber Daya Manusia dan Pengawasan Fungsional terhadap Efektivitas Pengelolaan Keuangan Daerah (Studi Empiris pada Satuan Kerja Perangkat Daerah Kota Pekanbaru)

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    This study aimed to examine the influence of the government internal control System, the human resources competencies and functional control on the effectiveness of the financial management area. This study was conducted at SKPD of Pekanbaru city. The population in this study were employed who worked in the SKPD Pekanbaru city (32 government agencies). The sampling method used in this study is purposive sampling method. The respondent in this study is the head of SKPD, the head of financial, treasurer of SKPD and PPTK SKPD. The sample used in this study were 120 respondents. The hypotheses then tested is multiple linear regression analysis by using SPSS version 20.0. The result of this study indicated that the government internal control System, the human resources competencies and functional control has significantly effect on effectiveness of the financial management area. The magnitude of the effect (R2) the government internal control System, the human resources competencies and functional control on the effectiveness of the financial management area was 48,5%. While the remaining 51,5% is influenced by other independent variabel that are not observed in this study

    VII Zw 403: H I structure in a blue compact dwarf galaxy

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    ‘In these times, during the rise in the popularity of institutional repositories, the Society does not forbid authors from depositing their work in such repositories. However, the AAS regards the deposit of scholarly work in such repositories to be a decision of the individual scholar, as long as the individual's actions respect the diligence of the journals and their reviewers.’ Original article can be found at : http://iopscience.iop.org/ Copyright American Astronomical SocietyWe present optical (UBVJ), ultraviolet (FUV, NUV), and high-resolution atomic hydrogen (H I) observations of the nearby blue compact dwarf (BCD), VII Zw 403. We find that VII Zw 403 has a relatively high H I mass-to-light ratio for a BCD. The rotation velocity is nominally 10-15 km s(-1), but rises to similar to 20 km s(-1) after correction for the similar to 8-10 km s(-1) random motions present in the gas. The velocity field is complex, including a variation in the position angle of the major axis going from the northeast to the southwest parts of the galaxy. Our high-resolution Hi maps reveal structure in the central gas, including a large, low-density Hi depression or hole between the southern and northern halves of the galaxy, coincident with an unresolved X-ray source. Although interactions have been proposed as the triggering mechanism for the vigorous star formation occurring in BCDs, VII Zw 403 does not seem to have been tidally triggered by an external interaction, as we have found no nearby possible perturbers. It also does not appear to fall in the set of galaxies that exhibit a strong central mass density concentration, as its optical scale length is large in comparison to similar systems. However, there are some features that are compatible with an accretion event: optical/Hi axis misalignment, a change in position angle of the kinematic axis, and a complex velocity field.Peer reviewe

    Multi-band optical variability of three TeV Blazars on Diverse Timescales

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    We present our optical photometric observations of three TeV blazars, PKS 1510-089, PG 1553+113 and Mrk 501 taken using two telescopes in India, one in Bulgaria, one in Greece and one in Serbia during 2012 - 2014. These observations covered a total of 95 nights with a total of 202 B filter frames, 247 images in V band, 817 in R band while 229 images were taken in the I filter. This work is focused on multi-band flux and colour variability studies of these blazars on diverse timescales which are useful in understanding the emission mechanisms. We studied the variability characteristics of above three blazars and found all to be active over our entire observational campaigns. We also searched for any correlation between the brightness of the sources and their colour indices. During the times of variability, no significant evidence for the sources to display spectral changes correlated with magnitude was found on timescales of a few months. We briefly discuss the possible physical mechanisms most likely responsible for the observed flux variability.Comment: 11 pages, 7 figures, 9 tables. Accepted for publication in MNRA

    Reduced executive and default network functional connectivity in cigarette smokers

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    Altered functional connectivity has been associated with acute and chronic nicotine use. Connectivity alterations, specifically in the right and left executive control networks (RECN/LECN) and the default mode network (DMN), may contribute to the addiction cycle. The objective of this study was to determine if executive control network (ECN) and DMN connectivity is different between non‐smokers and smokers and whether reductions in connectivity are related to chronic cigarette use. The RECN, LECN, and DMN were identified in resting state functional magnetic resonance imaging data in 650 subjects. Analyses tested for group differences in network connectivity strength, controlling for age and alcohol use. There was a significant group effect on LECN and DMN connectivity strength with smokers (n = 452) having lower network strengths than non‐smokers (n = 198). Smokers had lower connectivity than non‐smokers associated with key network hubs: the dorsolateral prefrontal cortex, and parietal nodes within ECNs. Further, ECN connectivity strength was negatively associated with pack years of cigarette use. Our data suggest that chronic nicotine use negatively impacts functional connectivity within control networks that may contribute to the difficulty smokers have in quitting. Hum Brain Mapp 36:872–882, 2015. © 2014 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110754/1/hbm22672.pd

    Dynamics of a hyperbolic system that applies at the onset of the oscillatory instability

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    A real hyperbolic system is considered that applies near the onset of the oscillatory instability in large spatial domains. The validity of that system requires that some intermediate scales (large compared with the basic wavelength of the unstable modes but small compared with the size of the system) remain inhibited; that condition is analysed in some detail. The dynamics associated with the hyperbolic system is fully analysed to conclude that it is very simple if the coefficient of the cross-nonlinearity is such that , while the system exhibits increasing complexity (including period-doubling sequences, quasiperiodic transitions, crises) as the bifurcation parameter grows if ; if then the system behaves subcritically. Our results are seen to compare well, both qualitatively and quantitatively, with the experimentally obtained ones for the oscillatory instability of straight rolls in pure Rayleigh - Bénard convection
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