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Periodic Pattern (periodic + pattern)
Selected AbstractsDaily pattern of some fatty acids in the athletic horseJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 1 2009G. Piccione Summary In the sport field, non-esterified fatty acids (NEFA) are important for the physical performance during the aerobic exercise of short intensity and long duration. In man, rat, goat and in the sedentary horse studies on the chronometabolism showed the presence of a circadian rhythm of the plasmatic concentration of NEFA while data for the athletic horse are lacking. To define a chronogram helpful for a specific planning and the differentiation of the training programmme in the athletic horse, the circadian pattern of some fatty acids (NEFA, palmitic, stearic, oleic, linoleic and linolenic acids) was studied in five Sella Italiana horses. These horses trained following a daily model of activity consisting of walk, trot, gallop and jump of obstacles of different heights. Blood samples were collected from the jugular vein every 4 h, starting at 08:00 hours, for 2 days to assess the concentrations of total NEFA (by spectrophotometry), palmitic, stearic, oleic, linoleic and linolenic acids (by gas chromatography). anova for repeated measures showed a statistical significant effect of the time of the day in NEFA, oleic and linolenic acids. The application of the periodic model showed the periodic pattern of NEFA, oleic, linoleic and linolenic acids. Acrophases were in the afternoon for all parameters. The results obtained showed a different trend of the circadian pattern of the studied parameters in the athletic horse than in the sedentary one because the physical activity and the post-prandial metabolism acted as zeitgebers. [source] Periodic spotted patterns in semi-arid vegetation explained by a propagation-inhibition modelJOURNAL OF ECOLOGY, Issue 4 2001P. Couteron Summary 1,Vegetation cover regularly punctuated by spots of bare soil is a frequent feature of certain semi-arid African landscapes, which are also characterized by banded vegetation patterns (i.e. tiger bush). 2,The propagation-inhibition (PI) model suggests that a periodic pattern characterized by a dominant wavelength can theoretically establish itself through a Turing-like spatial instability depending only on a trade-off between facilitative and competitive interactions among plants. Under strictly isotropic conditions, spotted and banded patterns are distinct outcomes of a unique process, whereas anisotropy leads to a banded structure. The model predicts that spotted patterns will have a lower dominant wavelength than bands. 3,We test some outcomes of the PI model against vegetation patterns observable in aerial photographs from West Africa. Two sites with rainfall of c. 500,600 mm year,1 were studied: a 525-ha plain in north-west Burkina Faso and a 300-ha plateau in southern Niger. Digitized photographs were subjected to spectral analysis by Fourier transform in order to quantify vegetation patterns in terms of dominant wavelengths and orientations. 4,Spotted vegetation proved highly periodic. The characteristic range of dominant wavelengths (30,50 m) was similar at two sites more than 500 km apart. The PI model suggests that spots may occur as a hexagonal lattice but there is little evidence of such patterning in the field. A dominant wavelength was far quicker to establish in simulations (c. 102,103 years for annual grasses) than a hexagonal symmetry (c. 105 years), and observed patterns are therefore likely to be far from the asymptotic structure. 5,Elongated and smudged spots that locally became flexuous bands have been observed in southern Niger. This pattern that had a dominant wavelength of 50 m but lacked any dominant orientation can be interpreted as a transition from spots to bands under fairly isotropic conditions. 6,The PI model provides a framework for further investigation of patterns in semi-arid vegetation and may be of a broader ecological application. [source] Dexterous manipulation of an object by means of multi-DOF robotic fingers with soft tipsJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 7 2002Pham Thuc Anh Nguyen This article analyzes the dynamics of motion of various setups of two multiple degree-of-freedom (DOF) fingers that have soft tips, in fine manipulation of an object, and shows performances of their motions via computer simulation. A mathematical model of these dynamics is described as a system of nonlinear differential equations expressing motion of the overall fingers-object system together with algebraic constraints due to tight area contacts between the finger-tips and surfaces of the object. First, problems of (1) dynamic, stable grasping and (2) regulation of the object rotational angle by means of a setup of dual two-DOF fingers, are treated. Second, the problem of regulating the position of the object mass center by means of a pair of two-DOF and three-DOF fingers is considered. Third, a set of dual three-DOF fingers is treated, in order to let it perform a sophisticated task, which is specified by a periodic pattern of the object posture and a constant internal force. In any case, there exist sensory-motor coordinations, which are described by analytic feedback connections from sensing to actions at finger joints. In the cases of setpoint control problems, convergences of motion to secure grasping together with the specified object rotational angle and/or the specified object mass center position, are proved theoretically. A constraint stabilization method (CSM) is used for solving numerically the differential algebraic equations to show performances of the proposed sensory-feedback schemes. © 2002 Wiley Periodicals, Inc. [source] Periodic electroencephalogram complexes in a patient with variant Creutzfeldt,Jakob diseaseANNALS OF NEUROLOGY, Issue 2 2006Simona Binelli MD Objective Based on the current criteria, the diagnosis of "possible" or "probable" variant Creutzfeldt,Jakob disease (vCJD) implies the absence of periodic sharp wave complexes (PSWCs) in the electroencephalogram (EEG). To verify this point, we investigated the development of the EEG changes along the course of the disease in a pateint with vCJD. Methods Long-lasting EEG-polygraphic recordings were performed once a month during the last year of illness. Results We found the occurrence of a typical EEG periodic pattern in the late clinical stage of the vCJD patient. Interpretation In the light of our finding, the diagnostic criteria for vCJD should be amended to include the possibility of a typical periodic EEG in advanced stages of disease in cases with long survival. Ann Neurol 2006;59:423,427 [source] Intraday Volatility Patterns in the Taiwan Stock Market and the Impact on Volatility ForecastingASIA-PACIFIC JOURNAL OF FINANCIAL STUDIES, Issue 1 2010Yaw-Huei Wang G10; C10; C30 Abstract Given the growing importance of the Taiwan stock market, the present study sets out to provide a comprehensive investigation of the intraday time series of the Taiwan Stock Exchange Capitalization Weighted Stock Index (TAIEX). We begin by exploring the intraday volatility patterns and then go on to examine their impact on intraday volatility forecasting. We find that the volatility of the TAIEX returns exhibits an L-shaped intraday periodic pattern, which is distinct across each day of the week. Our empirical results indicate that taking the intraday periodic pattern into account in a generalized autoregressive conditional heteroskedasticity model can substantially improve the precision of intraday volatility forecasting. [source] The reaction-diffusion system: a mechanism for autonomous pattern formation in the animal skinGENES TO CELLS, Issue 6 2002Shigeru Kondo How do animals acquire their various skin patterns? Although this question may seem easy, in fact it is very difficult to answer. The problem is that most animals have no related structures under the skin; therefore, the skin cells must form the patterns without the support of a prepattern. Recent progress in developmental biology has identified various molecular mechanisms that function in setting the positional information needed for the correct formation of body structure. None of these can explain how skin pattern is formed, however, because all such molecular mechanisms depend on the existing structure of the embryo. Although little is known about the underlying molecular mechanism, many theoretical studies suggest that the skin patterns of animals form through a reaction-diffusion system,a putative ,wave' of chemical reactions that can generate periodic patterns in the field. This idea had remained unaccepted for a long time, but recent findings on the skin patterns of fish have proved that such waves do exist in the animal body. In this review, we explain briefly the principles of the reaction-diffusion mechanism and summarize the recent progress made in this area. [source] Size reduction of microwave and millimeter-wave passive circuits by UC-PBG in standard 0.18-,m CMOS technologyMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2008Shuiyang Lin Abstract Size reduction of microwave and millimeter-wave (mm-wave) passive circuits incorporating a defective uniplanar compact photonic bandgap (UC-PBG) slow-wave structure is investigated. Benefited from the multilayer mental technology of the standard 0.18-,m CMOS process, thin film microstrip structure is properly constructed on the lossy silicon substrate to reduce substrate loss. Defected periodic patterns on the ground plane are used to contribute to an enhancement of the effective dielectric constant and the slow-wave factor is 14% increased by the use of UC-PBG ground. Microwave and mm-wave passive circuits including resonator and filter are designed and fabricated. Measured results show that the use of UC-PBG ground has induced a frequency drop of 14% and validate the size reduction concept by using UC-PBG. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2251,2254, 2008; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.23643 [source] Intradaily periodicity and volatility spillovers between international stock index futures marketsTHE JOURNAL OF FUTURES MARKETS, Issue 6 2005Chunchi Wu This paper examines short-run information transmission between the U.S. and U.K. markets using the S&P 500 and FTSE 100 index futures. Ultrahighfrequency futures data are employed,which have a number of advantages over the low-frequency spot data commonly used in previous studies,in establishing that volatility spillovers are in fact bidirectional. The generalized autoregressive conditionally heteroskedastic model (GARCH) is employed to estimate the mean and volatility spillovers of intraday returns. A Fourier flexible function is utilized to filter the intradaily periodic patterns that induce serial correlation in return volatility. It was found that estimates of volatility persistence and speed of information transmission are seriously affected by intradaily periodicity. The bias in parameter estimation is removed by filtering out the intradaily periodic component of the transaction data. Contrary to previous findings, there is evidence of spillovers in volatility between the U.S. and U.K. markets. Results indicate that the volatility of the U.S. market is affected by the most recent volatility surprise in the U.K. market. © 2005 Wiley Periodicals, Inc. Jrl Fut Mark 25:553,585, 2005 [source] Transverse pattern formation and its control in photorefractive opticsANNALEN DER PHYSIK, Issue 7-8 2004C. Denz Abstract A wealth of periodic transverse patterns is observed in nonlinear optical, photorefractive single-feedback systems. It is the extension of a photorefractive medium in the direction of propagation of the laser beam that allows for the formation of stable hexagons, squares, rhombuses and dodecagons above the first bifurcation of the system. In this article we review the formation of these periodic patterns and present linear and nonlinear stability analyses that predict the type of pattern to appear. Amplitude equations for the interactions of unstable sidebands are introduced. We compare numerical and experimental results on two-dimensional transverse pattern formation. We present control methods for the invasive and non-invasive manipulation of different pattern states using a Fourier filtering technique. [source] | ||||||||||||||||