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Regression Curve (regression + curve)
Selected AbstractsProgramming Optimal Atrioventricular Delay in Dual Chamber Pacing Using Peak Endocardial Acceleration: Comparison with a Standard Echocardiographic ProcedurePACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1p2 2003JEAN-MARC DUPUIS DUPUIS, J.-M.,et al.: Programming Optimal Atrioventricular Delay in Dual Chamber Pacing Using Peak Endocardial Acceleration: Comparison with a Standard Echocardiographic Procedure.Optimization of programmed atrioventricular delay in dual chamber pacing is essential to the hemodynamic efficiency of the heart. Automatic AV delay optimization in an implanted pacemaker is highly desirable. Variations of peak endocardial acceleration (PEA) with AV delay at rest correlate well with echocardiography derived observations, particularly with end-diastolic filling and mitral valve closure timings. This suggests the possibility of devising a procedure for the automatic determination of the optimal AV delay. The aim of this study was to compare a proposed algorithm for optimal AV delay determination with an accepted echocardiographic method. Fifteen patients with high degree AV block received BEST-Living pacing systems. Automatic AV delay scans were performed at rest (60,300 ms in 20-ms steps with 60 beats per step) in DDD at 90 ppm, while simultaneously recording cycle-by-cycle PEA values, which were averaged for each AV delay to obtain a PEA versus AV delay curve. Nonlinear regression analysis based on a Boltzmann sigmoid curve was performed, and the optimal AV delay (OAVD) was chosen as the sigmoid inflection point of the regression curve. The OAVD was also evaluated for each patient using the Ritter echocardiographic method. Good sigmoid fit was obtained in 13 of 15 patients. The mean OAVD obtained by the PEA sigmoid algorithm was146.9 ± 32.1 ms, and the corresponding result obtained by echocardiography was156.4 ± 34.3 ms(range 31.8,39.7 ms). Correlation analysis yielded r = 0.79, P = 0.0012. In conclusion, OAVD estimates obtained by PEA analysis during automatic AV delay scanning are consistent with those obtained by echocardiography. The proposed algorithm can be used for automatic OAVD determination in an implanted pacemaker pulse generator. (PACE 2003; 26:[Pt. II]:210,213) [source] The Relationship Between CAG Repeat Length and Age of Onset Differs for Huntington's Disease Patients with Juvenile Onset or Adult OnsetANNALS OF HUMAN GENETICS, Issue 3 2007J. Michael Andresen Summary Age of onset for Huntington's disease (HD) varies inversely with the length of the disease-causing CAG repeat expansion in the HD gene. A simple exponential regression model yielded adjusted R-squared values of 0.728 in a large set of Venezuelan kindreds and 0.642 in a North American, European, and Australian sample (the HD MAPS cohort). We present evidence that a two-segment exponential regression curve provides a significantly better fit than the simple exponential regression. A plot of natural log-transformed age of onset against CAG repeat length reveals this segmental relationship. This two-segment exponential regression on age of onset data increases the adjusted R-squared values by 0.012 in the Venezuelan kindreds and by 0.035 in the HD MAPS cohort. Although the amount of additional variance explained by the segmental regression approach is modest, the two slopes of the two-segment regression are significantly different from each other in both the Venezuelan kindreds [F(2, 439) = 11.13, P= 2 × 10,5] and in the HD MAPS cohort [F(2, 688) = 38.27, P= 2 × 10,16]. In both populations, the influence of each CAG repeat on age of onset appears to be stronger in the adult-onset range of CAG repeats than in the juvenile-onset range. [source] Implications of 19th century landscape patterns for the recovery of Fagus crenata forestsAPPLIED VEGETATION SCIENCE, Issue 2 2005Shinya Ohtani Abstract Questions: What is the effect of the 19th century (pre-industrialization) landscape pattern on the recovery of climax forests in cool-temperate mountain areas dominated by Fagus crenata (Japanese beech)? Location: Secondary forests on Mt. Daisen, western Japan. Methods: Vegetation patterns before and after industrialization were obtained from maps drawn in 1898 and 1979. Tree measurements were made in 12 plots in 1997. Correlation between current Fagus crenata dominance and forest edge in the 19th century was analysed using an S-shaped regression curve. Fagus juvenile density was counted in the plots, and distances from each plot to the five nearest mother trees were measured to determine the dispersal kernel. Results: Secondary grassland covered a substantial area in 1898, whereas forest covered most of the area in 1997. Fagus was dominant in places in the interior forest 100 years ago, and mature Fagus trees were absent in secondary forests that had been grasslands in 1898. The expected number of juveniles decreased to one individual per 100 m2 at 43.5 m from the mother tree. Conclusions: The pre-industrialization landscape greatly affected recovery of Fagus forest. Forests found on the 1898 vegetation map might have acted as refugia for Fagus. The limited dispersal ability of Fagus suggests that it would take many generations (several hundred years) for Fagus forests to recover at the centre of what had been grasslands in the 19th century. [source] Evaluation of Electron Population Terms for ,rSe,3,4p, ,rS,3,3p, and ,rO,3,2p: How Do HOMO and LUMO Shrink or Expand Depending on Nuclear Charges?CHEMISTRY - A EUROPEAN JOURNAL, Issue 24 2008Waro Nakanishi Prof. Abstract Electron population terms ,, are evaluated for N=Se, S, and O. Calculations are performed on HOMO and LUMO constructed by pure atomic 4p(Se), 3p(S), and 2p(O) orbitals, employing the 6-311+G(3d) and/or 6-311++G(3df,3pd) basis sets at the HF, MP2, and DFT (B3,LYP) levels. Se4+, Se2+, Se0, and Se2, with the Oh symmetry are called G(A: Se) and HSe+, H2Se, and HSe, with the C,h or C2v symmetry are named G(B: Se), here [G(A+B: Se) in all]. HOMO and LUMO in G(A+B: N) (N=Se, S, and O) satisfy the conditions of the calculations for ,,. The ,,4p, ,,3p, and ,,2p values correlate well with the corresponding MO energies (,N) for all calculation levels employed. Plots of ,,HOMO and ,,LUMO versus Q(N) (N=Se, S, and O) at the HF and MP2 levels are analyzed as two correlations. However, the plots at the DFT level can be analyzed as single correlation. A regression curve is assumed for the analysis. Behaviors of ,, clarify how valence orbitals shrink or expand depending on Q(N). The applicability of ,, is examined to establish a new method that enables us to analyze chemical shifts with the charge effect separately from others. A utility program derived from the Gaussian 03 (NMRANAL-NH03G) is applied to evaluate ,, and examine the applicability to the NMR analysis. [source] Simultaneous quantification of CTN986 and its deglycosylation products in rat serum using liquid chromatography/tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2006Jifen Guo A quantitative method for the simultaneous determination of CTN986, a flavonol triglycoside, and its two deglycosylation products rutin and hirsutin in rat serum was developed and validated for the investigation of the pharmacokinetics of CTN986. Analytes were isolated from the serum samples (200,µL) prior to analysis by liquid chromatography/tandem mass spectrometry (LC/MS/MS) using C18 solid-phase extraction, and were separated on a Zorbax C8 reversed-phase column with an isocratic mobile phase consisting of methanol/isopropanol/water/formic acid (20:10:70:0.1, v/v/v/v). The protonated analytes generated in the positive ion mode were monitored through multiple reaction monitoring in an eletrospray ionization source. Calibration was performed by internal standardization with CTN987, a flavonoid structurally similar to CTN986, and regression curves were constructed ranging from 2 to 1000,ng/mL in 200,µL serum samples. The intra- and inter-day precision values were below 11% and accuracy was between ,2.37 and 1.4% for all quality control samples. This quantitation method was successfully applied to pharmacokinetic studies of CTN986 in rats following oral and intravenous administration. Rutin and hirsutin were not detected in rat serum. Copyright © 2006 John Wiley & Sons, Ltd. [source] Salmonella or Campylobacter gastroenteritis prior to a cancer diagnosis does not aggravate the prognosis: a population-based follow-up studyAPMIS, Issue 2 2010KIM O. GRADEL Gradel KO, Nørgaard M, Schønheyder HC, Dethlefsen C, Ejlertsen T, Kristensen B, Nielsen H. Salmonella or Campylobacter gastroenteritis prior to a cancer diagnosis does not aggravate the prognosis: a population-based follow-up study. APMIS 2010; 118: 136,42. We hypothesized that preceding zoonotic Salmonella or Campylobacter gastroenteritis aggravated the prognosis in cancer patients. Exposed patients comprised all of those diagnosed with first-time Salmonella/Campylobacter gastroenteritis from 1991 and with first-time cancer diagnosis thereafter (through 2003) in two Danish counties. These patients were matched for main cancer type, gender, age and calendar period to unexposed cancer patients, i.e. those without Salmonella/Campylobacter gastroenteritis. We compared cancer stage by age- and comorbidity-adjusted logistic regression analysis, survival by comorbidity-adjusted Cox's regression analysis and mortality dependent on the time period between Salmonella/Campylobacter gastroenteritis and cancer by spline regression curves. The study cohort comprised 272 Salmonella/Campylobacter -exposed cancer patients and 2681 unexposed cancer patients. Prevalence odds ratios [95% confidence intervals (CI)] in exposed as compared with unexposed patients were 0.96 (0.74,1.25) for localized tumours, 1.15 (0.87,1.54) for regional spread and 1.14 (0.84,1.55) for metastases. Adjusted mortality rate ratios (95% CI) were 0.93 (0.75,1.16) for 0,1 year, 1.08 (0.84,1.39) for 2,5 years and 1.02 (0.60,1.73) for the remaining period. Mortality estimates did not change in relation to the time period between gastroenteritis and cancer. Salmonella/Campylobacter gastroenteritis prior to cancer was associated with neither the cancer stage nor a poorer prognosis. [source] Wavelength-dispersive X-ray fluorescence analysis of ancient glasses,ARCHAEOMETRY, Issue 4 2002R. Falcone The application of X-ray fluorescence to the study of the composition of ancient glasses has been limited by the large amount of material required for samples. In this paper the setting of a reduced sampling XRF method for the analysis of ancient glasses is described. The method involves the preparation of glass beads by melting the sample with lithium tetraborate flux. By means of reference and synthetic samples, the method allows regression curves to be set, covering broad ranges from ppm to high concentrations. By means of a single program, up to 31 elements of interest in the study of ancient glass are analysed. The reproducibility, sensitivity and reliability of the method are discussed. The results demonstrate that 0.2 g of glass is sufficient to obtain accurate and sensitive analyses for most of the elements of interest. [source] Delayed umbilical cord clamping at birth has effects on arterial and venous blood gases and lactate concentrationsBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 6 2008N Wiberg Objective, To estimate the influence of delayed umbilical cord clamping at birth on arterial and venous umbilical cord blood gases, bicarbonate (), base excess (BE) and lactate in vigorous newborns. Setting, University hospital. Design, Prospective observational. Sample, Vaginally delivered term newborns. Material and methods, Umbilical cord arterial and venous blood was sampled repeatedly every 45 seconds (T0= time zero; T45= 45 seconds, T90= 90 seconds) until the cord pulsations spontaneously ceased in 66 vigorous singletons with cephalic vaginal delivery at 36,42 weeks. Longitudinal comparisons were performed with the Wilcoxon signed-ranks matched pairs test. Mixed effect models were used to describe the shape of the regression curves. Main outcome measures, Longitudinal changes of umbilical cord blood gases and lactate. Results, In arterial cord blood, there were significant decreases of pH (7.24,7.21), (18.9,18.1 mmol/l) and BE (,4.85 to ,6.14 mmol/l), and significant increases of PaCO2 (7.64,8.07 kPa), PO2 (2.30,2.74 kPa) and lactate (5.3,5.9 mmol/l) from T0 to T90, with the most pronounced changes at T0,T45. Similar changes occurred in venous blood pH (7.32,7.31), (19.54,19.33 mmol/l), BE (,4.93 to ,5.19 mmol/l), PaCO2 (5.69,5.81 kPa) and lactate (5.0,5.3 mmol/l), although the changes were smaller and most pronounced at T45,T90. No significant changes were observed in venous PO2. Conclusion, Persistent cord pulsations and delayed cord clamping at birth result in significantly different measured values of cord blood acid,base parameters. [source] | |||||||||||||