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Double Peak (double + peak)
Selected AbstractsImplications of ,cyclical' population dynamics for the conservation of Irish hares (Lepus timidus hibernicus)JOURNAL OF ZOOLOGY, Issue 3 2006J. C. Reynolds Abstract The Irish hare Lepus timidus hibernicus is of priority conservation concern in Northern Ireland, based on a perceived decline in abundance during the 20th century and on two surveys in 1994,1996 and 2002 that suggested low densities. We reanalysed a 10-year time series [Northern Ireland Rabbit Survey (NIRS)] that has been key evidence of decline, to derive an annual index of abundance during 1986,1995. This showed a rise to a double peak followed by a trough. We compared these Northern Ireland data with two datasets for Lepus timidus scoticus. A 40-year annual index derived from hare bags on Scottish shooting estates [National Game-Bag Census (NGC)] showed strong fluctuations, each lasting several years. Autocorrelation analysis of the NGC data showed elements of cyclical behaviour, with distinct phases and a 16-year period. A previously published 30-year survey of introduced L. t. scoticus in northern England also showed large multi-year fluctuations and phasic behaviour, albeit on a shorter time scale. The NIRS index was strongly correlated with NGC data for the same years, suggesting that it too reflected part of a natural population dynamic. The Species Action Plan for L. t. hibernicus in Northern Ireland includes the aims of maintaining the existing range and demonstrating increase by 2005, and of doubling the population by 2010. We suggest that these aims and the supporting monitoring strategy are inappropriate for a species that shows multi-annual fluctuations in abundance throughout its geographical range. It is important to distinguish self-correcting population processes from trends requiring remedial conservation action. [source] Unusual Crystallization Behavior in Nylon-6 and Nylon-6/Montmorillonite Nanocomposite FilmsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 14 2004Zhudi Zhao Abstract Summary: The crystallization behavior of nylon-6 and nylon-6/montmorillonite nanocomposite films with different heat histories was investigated by wide-angle X-ray diffraction (WAXD). For nylon-6 films isothermally crystallized above 170,°C or annealed at 200,°C and then quenched in ice water, a crystalline peak appeared at 2,,=,28.5°. This crystalline peak was strong in intensity for the former and weak for the latter. However, for nylon-6 films cooled in air after isothermal crystallization or annealing, no crystalline peak at 2,,=,28.5° was observed in the WAXD patterns. For nylon-6/montmorillonite nanocomposite films annealed above 140,°C, a crystalline double peak was observed between the ,1 and ,2 peaks. The possible origins of the peak at 2,,=,28.5° and the crystalline double peak are discussed. WAXD patterns of isothermally crystallized nylon-6/montmorillonite nanocomposite films. [source] Effect of strain and alloy composition inhomogeneity on the electronic and optical properties of III-nitride semiconductorsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2008Nikos Skoulidis Abstract Using the empirical tight binding method with a sp3s* basis for the first neighbour interactions and only p,p interactions for the second neighbours, we calculated the optical properties near the fundamental gap of cubic GaxAl1,xN alloys for x<0.33 grown on a substrate whose lattice constant varies from the lattice constant of cubic AlN to GaN. We found that the spectra of the fully relaxed alloy have a tail with onset energy at the indirect gap of AlN and an edge at the direct gap of the alloy which follows the Vegard's law within 0.1 eV. The maximum of band gap for each alloy composition is found for a substrate with the lattice constant of the fully relaxed alloy. When the substrate composition is such that induces negative tetragonal strain on the alloy (,xx<0) the energy band gap is mainly affected by the alloy composition while for ,xx>0 the alloy composition has a limited effect. The total effect of substrate and alloy composition in the calculated range on the band gap can be as much as 0.4 eV and is mainly due to the valence band shift as the conduction band is only slightly affected by the substrate or the alloy composition. This band gap change is adequate to explain the experimentally observed double photoluminescence peak of open quantum dots. The energy separation of the double peak is 0.1 eV and one peak can be attributed to the tetragonically strained wetting layer and the other to the fully relaxed quantum dots. Furthermore the present results can be used to estimate any possible stoichiometric inhomogeneity and help design structures with specific energies for the pair of peaks. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Radiation and postirradiation crosslinking and structure of two unsaturated polyester resinsPOLYMER ENGINEERING & SCIENCE, Issue 9 2008Irina Puci Radiation and postirradiation crosslinking of two unsaturated polyester (UP) resins were monitored, and substantial differences in the reaction course and extents were observed. DSC thermograms of one of the resins showed double peaks and significantly lower residual reaction heats. Extraction revealed that gelation dose of the resin with double peak was twice the gelation dose of the other resin that had single peak in DSC thermograms. Although other components of the polyesters were identical, NMR spectra of the resin with a single peak revealed isophthalic units while in the polyester of the resin having double DSC peaks orthophthalic units were detected. Orthophthalate reduced the compatibility of polyester and styrene and caused the reaction-induced phase separation, influencing gel structure that was visible in scanning electron microscope micrographs. Previously, the double peaks in crosslinking thermograms of UP resins were usually attributed to initiator effects, but here no initiator was used, and, in the literature, we found that the double peaks are almost exclusively present in the thermograms of UP resins containing orthophthalates, whereas in resins with isophthalates double peaks almost never appear. Crosslinking extents were significantly higher in the resin-containing isophthalate and in both cases enhanced by postirradiation reaction that is often neglected. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Circadian Distribution of Paroxysmal Atrial Fibrillation in Patients with and without Structural Heart Disease in Untreated StateANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 3 2009Yoshiaki Deguchi M.D. Background: This study aimed to compare the circadian distribution of the onset, maintenance and termination of paroxysmal atrial fibrillation (PAF) between structural and non-structural heart diseases (SHD and NSHD, respectively) in the untreated state. Subjects and Methods: We included 217 patients with 338 PAF (79 SHD patients with 131 episodes; 138 NSHD patients with 207 episodes). The probabilities for the onset, maintenance and termination of PAF for each hour were analyzed using Holter monitoring data and harmonic models being fitted into a cosinusoidal function. Results: The SHD group had a triphasic circadian pattern at the onset with higher peaks at midnight, in the early morning and in the late afternoon (p < 0.05), whereas the NSHD group showed a single peak at midnight (p < 0.01). The probability of maintenance revealed a single peak during midnight (SHD, p < 0.0001; NHD, p < 0.01). The termination showed a peak at noon in the SHD group (p < 0.05), whereas there was a double peak at 10:00 am and 8:00 pm in the NSHD group (p = 0.06). RR intervals just after the PAF onset showed marked shortening in the daytime initiation PAF as compared to the nighttime initiation PAF in both SHD and NSHD groups (p < 0.01). Conclusion: These observations suggest that the SHD group has very complex onset hours, whereas the NSHD group shows complex termination hours. Reflexly accelerated sympathetic tone just after the PAF onset is suggested in the daytime initiation PAF. [source] A simple pharmacokinetics subroutine for modeling double peak phenomenonBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 3 2006Ahmad Mirfazaelian Abstract Double peak absorption has been described with several orally administered drugs. Numerous reasons have been implicated in causing the double peak. DRUG-KNT,a pharmacokinetic software developed previously for fitting one and two compartment kinetics using the iterative curve stripping method,was modified and a revised subroutine was incorporated to solve double-peak models. This subroutine considers the double peak as two hypothetical doses administered with a time gap. The fitting capability of the presented model was verified using four sets of data showing double peak profiles extracted from the literature (piroxicam, ranitidine, phenazopyridine and talinolol). Visual inspection and statistical diagnostics showed that the present algorithm provided adequate curve fit disregarding the mechanism involved in the emergence of the secondary peaks. Statistical diagnostic parameters (RSS, AIC and R2) generally showed good fitness in the plasma profile prediction by this model. It was concluded that the algorithm presented herein provides adequate predicted curves in cases of the double peak phenomenon. Copyright © 2006 John Wiley & Sons, Ltd. [source] Physically-based modelling of double-peak discharge responses at Slapton Wood catchmentHYDROLOGICAL PROCESSES, Issue 10 2008Stephen J Birkinshaw Abstract Heavy winter rainfall produces double-peak hydrographs at the Slapton Wood catchment, Devon, UK. The first peak is saturation-excess overland flow in the hillslope hollows and the second (i.e. the delayed peak) is subsurface stormflow. The physically-based spatially-distributed model SHETRAN is used to try to improve the understanding of the processes that cause the double peaks. A three-stage (multi-scale) approach to calibration is used: (1) water balance validation for vertical one-dimensional flow at arable, grassland and woodland plots; (2) two-dimensional flow for cross-sections cutting across the stream valley; and (3) three-dimensional flow in the full catchment. The main data are for rainfall, stream discharge, evaporation, soil water potential and phreatic surface level. At each scale there was successful comparison with measured responses, using as far as possible parameter values from measurements. There was some calibration but all calibrated values at one scale were used at a larger scale. A large proportion of the subsurface runoff enters the stream from three dry valleys (hillslope hollows), and previous studies have suggested convergence of the water in the three large hollows as being the major mechanism for the production of the delayed peaks. The SHETRAN modelling suggests that the hillslopes that drain directly into the stream are also involved in producing the delayed discharges. The model shows how in the summer most of the catchment is hydraulically disconnected from the stream. In the autumn the catchment eventually ,wets up' and shallow subsurface flows are produced, with water deflected laterally along the soil-bedrock interface producing the delayed peak in the stream hydrograph. Copyright © 2007 John Wiley & Sons, Ltd. [source] Radiation and postirradiation crosslinking and structure of two unsaturated polyester resinsPOLYMER ENGINEERING & SCIENCE, Issue 9 2008Irina Puci Radiation and postirradiation crosslinking of two unsaturated polyester (UP) resins were monitored, and substantial differences in the reaction course and extents were observed. DSC thermograms of one of the resins showed double peaks and significantly lower residual reaction heats. Extraction revealed that gelation dose of the resin with double peak was twice the gelation dose of the other resin that had single peak in DSC thermograms. Although other components of the polyesters were identical, NMR spectra of the resin with a single peak revealed isophthalic units while in the polyester of the resin having double DSC peaks orthophthalic units were detected. Orthophthalate reduced the compatibility of polyester and styrene and caused the reaction-induced phase separation, influencing gel structure that was visible in scanning electron microscope micrographs. Previously, the double peaks in crosslinking thermograms of UP resins were usually attributed to initiator effects, but here no initiator was used, and, in the literature, we found that the double peaks are almost exclusively present in the thermograms of UP resins containing orthophthalates, whereas in resins with isophthalates double peaks almost never appear. Crosslinking extents were significantly higher in the resin-containing isophthalate and in both cases enhanced by postirradiation reaction that is often neglected. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] | |||||||||||||