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PubMed2003

Optimization of structural variables of a flextensional transducer by the statistical multiple regression analysis method.

The performance of an acoustic transducer is determined by the effects of many structural variables, and in most cases the influences of these variables are not linearly independent of each other. To achieve optimal performance of an acoustic transducer, we must consider the cross-coupled effects of its structural variables. In this study, with the finite-element method, the variation of the operation frequency and sound pressure of a flextensional transducer in relation to its structural variables is analyzed. Through statistical multiple regression analysis of the results, functional forms of the operation frequency and sound pressure of the transducer in terms of the structural variables were derived, with which the optimal structure of the transducer was determined by means of a constrained optimization technique, the sequential quadratic programming method of Phenichny and Danilin. The proposed method can reflect all the cross-coupled effects of multiple structural variables, and can be extended to the design of general acoustic transducers.

Journal Article↗
PubMed1996

Evaluation of plant availability of soil trace metals by chemical fractionation and multiple regression analysis.

Soil samples with a range of chemical and physical properties were collected from 10 different rural regions of China. Trace metals (Ni, Co, Cu, and Pb) in the soils were partitioned by a sequential extraction procedure into Mg(NO(3))(2) extractable (F1), CH(3)COONa extractable (F2), NH(2)OH.HCl extractable (F3), HNO(3)?H(2)O(2) extractable (F4), and residual (F5) fractions. Chemical fractionation showed that F1 fraction of the metals was less than 1% and residue was the dominant form for Cu and Ni in all samples, and for Co in most of the samples. Significant interrelationships of the fractions varied considerably with the different metals. Winter wheat (Triticum aestivum L.) and alfalfa (Medicago sativa L.) had been grown on the soils in a pot-culture experiment under greenhouse conditions for 40 days. Metal availability to the plants was evaluated by simple and multiple regression analysis. The Mg(NO(3))(2) extractable Co (F1) was significantly correlated with Co concentrations in different parts of wheat and in the whole of alfalfa. For the other metals, the independent variables of the multiple regression models, chosen by stepwise selection, were given as: F1 and F2 + F3 + F4 for Ni; F1, F2 + F3 and F4 for Cu; and F3 + F4 for Pb. The results of this study demonstrate that the sequential extraction procedure, in conjunction with multiple regression models using a combination of correlated fractions as an independent variable, may be useful for the prediction of plant absorption of trace metals in soils.

Journal Article↗
PubMed1984

Implications of regression analysis and correlational data between subtests of the WISC-R and the PPVT-R for a delinquent population.

Computed correlations between the subscales of the Wechsler Intelligence Scales for Children-Revised (WISC-R) and the Peabody Picture Vocabulary Test-Revised (PPVT-R) using as a sample 72 adjudicated male delinquents aged 13-10 to 16-11. Significant relationships at the .0001 level were obtained for 10 subtests with only one, Object Assembly, computed at the .001 level. A forward selection multiple regression analysis resulted in six subtests of the WISC-R correlating to the PPVT-R with a R2 value of .78. The significance and the implications of this relationship for the juvenile delinquent population were discussed.

Adolescent↗
PubMed2000

Factors influencing efficacy of nitrate therapy for stable angina pectoris: a multiple linear regression analysis.

In an open-label self-controlled study of 1,350 patients with stable angina pectoris (SAP), we previously demonstrated that 50 mg of isosorbide mononitrate (ISMN) slow release formulation once daily not only provided a better antianginal effect but also a better quality of life (QOL) than did the daily administration of multiple small doses of the compound. It is unknown whether certain patient characteristics contribute to this benefit. The objective of this article was to determine what independent factors contribute to this benefit. Multiple linear regression analysis was performed on the data from these 1,350 patients. Quality of life was assessed by the Marquis QOL-questionnaire for patients with angina and included the domains of immobility, pain, and psychological distress. For the purpose of this study, overall QOL was calculated as the pooled sums of the domain scores and expressed as mean scores on an ordinal scale of 10. Age did not influence the beneficial effect of nitrate therapy on QOL. Neither did gender, rhythmic disturbances, peripheral artery disease, or the concomitant use of calcium channel blockers or beta blockers. New York Heart Association (NYHA) angina classification was an independent variable: patients with a NYHA class I or II benefited less than did patients with NYHA III or IV (p = 0.02). Obese patients as well as hypertensive patients benefited less (p = 0.04 and 0.02), and smokers tended to benefit less also (p = 0.08). In contrast, hypercholesterolemia and diabetes mellitus improved the beneficial effect of nitrates on QOL (p = 0.03 and 0.05). The authors conclude that patients with coronary artery disease (CAD) and concomitant diabetes mellitus or hypercholesterolemia, a category particularly prone to early endothelial dysfunction and thus dysfunctional endogenous nitric oxide (NO) production, may benefit more from NO-donor therapy than patients without such concomitant conditions.

Angina Pectoris↗
PubMed1997

Respiratory resistive impedance in obstructive patients: linear regression analysis vs viscoelastic modelling.

The aim of this study was to test the ability of a simple two segment model to describe the frequency dependence of resistive impedance in obstructive patients, and to investigate the significance of parameters derived from this model. The study was performed in 38 patients, in the basal state and after inhalation of 200 micrograms salbutamol. Impedance data measured over 4-32 Hz were fitted by a general four parameter viscoelastic model describing gas redistribution, and completed by an inertial component. This model yielded Newtonian resistance (Rmin) and maximal resistance (Rmax = Rmin plus delayed resistance due to gas redistribution). Resistive impedance data were also submitted to linear regression analysis over the 4-16 and 17-32 Hz frequency ranges, which respectively, yielded resistive impedance extrapolated at 0 Hz (R0) and resistive impedance estimated at 32 Hz (R32). R0 and R32 were compared to Rmax and Rmin, respectively. The airway response to salbutamol inhalation was assessed by the percentage changes in these parameters (R0%, R32%, Rmax%, and Rmin%, respectively). Significant linear correlations (p < 0.0001) were found between R0 and Rmax, R32 and Rmin, and R0% and Rmax%. Furthermore, the linear regression lines of R0 vs Rmax, and R0% vs Rmax%, were not significantly different from the identity line. These results demonstrate that resistive impedance extrapolated at zero frequency is equivalent to maximal resistive impedance, and can be proposed as an index, not only of the level of airway obstruction, but also of its reversibility.

Administration, Inhalation↗
PubMed1997

Multiple linear regression analysis of blood pressure, hypertrophy, calcium and cadmium in hypertensive and non-hypertensive states.

High blood pressure causes heart disease and remains a major public health issue. This paper expands mathematically and mechanically on environmental heavy metal exposure and heart disease. In rabbits, mean blood pressure was measured by direct puncture of the middle ear artery. Measurements of calcium and cadmium levels were made by flame atomic absorption spectrophotometry in tissue from hypertensive and non-hypertensive rabbits. Relationships between blood pressure, hypertrophy, calcium and cadmium were tested using multiple regression analysis. Multiple linear relationships occurred showing the dependence of high blood pressure on hypertrophy, calcium and cadmium: hypertrophy on calcium, cadmium and high blood pressure; and calcium on cadmium, high blood pressure and hypertrophy. These data provide insight into the mechanism of elevated blood pressure on heavy metal and calcium accumulation, and cardiac hypertrophy.

Animals↗
PubMed2000

Patient-controlled analgesia and urinary retention following lower limb joint replacement: prospective audit and logistic regression analysis.

We studied a number of factors that may be associated with urinary retention, in particular the method of postoperative analgesia delivery, in 47 men and 69 women undergoing lower limb joint replacements. The following factors were studied: age, gender, height, weight, previous history of urinary retention, presence of symptoms suggestive of urinary tract obstruction, type of anaesthetic (general anaesthetic or spinal anaesthetic), type of postoperative analgesia (intramuscular or patient-controlled analgesia with morphine) and the total dose of morphine given. Urinary retention developed in 18.1% of patients. Stepwise logistic regression analysis was used to identify independent explanators of an increased probability of developing urinary retention. Three factors emerged - male gender, increasing age and the use of patient-controlled analgesia.

Adult↗
PubMed2026

The incidence and descriptive factors of calcaneal malunion after surgical fixation of intra-articular calcaneal fractures using the sinus tarsi approach: A retrospective cohort study with binary logistic regression analysis.

BACKGROUND: This study evaluated the incidence of calcaneal malunion after minimally invasive sinus tarsi approach (MIS-STA) in displaced intra-articular calcaneal fractures (I-ACFs) and identified related descriptive factors of calcaneal malunion. METHODS: A retrospective review of 99 displaced I-ACFs treated with MIS-STA was conducted. Demographic data, pre-operative radiographs, and operative details were analyzed. Outcomes included numerical rating scale (NRS) pain scores at rest and during activities of daily living (ADL), Foot and Ankle Ability Measure (FAAM) for ADL and radiographic parameters. Logistic regression was used to identify descriptive factors associated with malunion. RESULTS: Malunion occurred in 33/99 cases (33.3%). The significant descriptive factors were the initial B&#xf6;hler angle <&#x202f;0.5 &#xb0;, time to surgery >&#x202f;12.5 days, and Sanders type &#x2265;&#x202f;III. Malunion patients had significantly worse NRS and FAAM scores (p&#x202f;&#x2264;&#x202f;0.001). CONCLUSION: Calcaneal malunion after MIS-STA occurred in one-third of cases, with three descriptive factors identified and poorer outcomes observed. LEVEL OF EVIDENCE: III, Comparative retrospective study with binary logistic regression analysis.

Humans↗
PubMedDate not supplied

A multiple logistic regression analysis of risk factors in different subtypes of gastric ulcer.

BACKGROUND/AIMS: To elucidate the relationship among disparate ulcer risk factors in 3 subtypes of gastric ulcer. METHODOLOGY: One hundred and fifty-nine age-matched controls, 30 patients with ulcer craters in the gastric body (GU-I), 55 with coexistent gastroduodenal ulcer (GU-II), and 69 with ulcer craters in the prepyloric region (GU-III) were examined for potential risk factors. These included cigarette smoking, nonsteroidal anti-inflammatory drug use, Helicobacter pylori infection, gender and ABO blood group. Using multiple logistic regression analysis, Odds ratios of relevant risk factors associated with different subtypes of gastric ulcer were reported. RESULTS: Among all gastric ulcer subsets, cigarette smoking, nonsteroidal anti-inflammatory drugs use and H. pylori infection were independent ulcer risk factors. For GU-I, smoking (OR: 3.98; 95% CI: 1.44-11.0) and nonsteroidal anti-inflammatory drugs use (OR: 4.33; 95% CI: 1.10-17.1) raised the likelihood of ulceration. For GU-II and GU-III, smoking, nonsteroidal anti-inflammatory drug use and H. pylori infection were identified as risk factors. H. pylori infection carried the strongest association with gastroduodenal ulcer (OR: 9.29; 95% CI: 3.11-27.7) in GU-II, and nonsteroidal anti-inflammatory drug use generated the highest possibility of GU-III (OR: 11.3; 95% CI: 3.49-36.5). Nonsteroidal anti-inflammatory drug use also markedly raised the likelihood of multiple gastric ulcers (OR: 17.0; 95% CI: 4.21-68.9). CONCLUSIONS: Stratification analysis showed differential influences of risk factors on separate subtypes of gastric ulcer. These data support the hypothesis that peptic ulcer disease is heterogeneous in etiology and pathogenesis.

Aged↗
PubMed1993

Application of neural networks in the QSAR analysis of percent effect biological data: comparison with adaptive least squares and nonlinear regression analysis.

Artificial neural networks (ANN) can be used for the direct QSAR analysis of percent effect biological data, thus avoiding the bias introduced by arbitrarily chosen classes and the loss of information due to prior classification. For two data sets the ANN results are compared with those obtained by adaptive least squares and nonlinear regression analyses. In comparison with the other methods the neural network shows higher predictive power and does not require an explicit equation relating the observed effect to physicochemical descriptors.

Animals↗
PubMed1993

Clinical and nutritional factors predictive of plasma lipid unsaturation deficiency in advanced liver cirrhosis: a logistic regression analysis.

AIM: To identify those clinical and nutritional factors associated with plasma lipid unsaturation deficiency in cirrhosis. METHODS: Fatty acid profiles of plasma phospholipids (PL) and cholesteryl esters (CE) were measured in 101 inpatients with advanced cirrhosis and in 44 age- and sex-matched healthy controls. Double-bond index (DBI) was calculated for each fraction and binarily categorized in each patient using the 5th percentile of the control group as the cut-off limit. The association of 12 routine clinical, biological, and nutritional variables with derangement of each DBI was multivariately assessed by means of stepwise logistic regression analysis. RESULTS: The DBI of PL and CE were below the 5th percentile of the control group in 60 and 68 of 101 cirrhotic patients, respectively. After multivariate analyses, the variables found to be independent predictors of impaired unsaturation were: 1) The presence of moderate/severe malnutrition (odds ratio: 1.3-8.0 (95% CI); p < 0.05) and serum tau-GT > 1 mukat/L (odds ratio: 0.2-1.0; NS) for plasma PL, and 2) the presence of moderate/severe malnutrition (odds ratio: 1.8-17.4; p < 0.05), serum bilirubin > 50 mumol/L (odds ratio 1.7-14.5; p < 0.05) and serum tau-GT > 1 mukat/L (odds ratio 0.1-1.1; NS) for CE. CONCLUSION: Malnutrition appears to be a major factor for impaired lipid unsaturation in advanced cirrhosis. Thus, the possibility of improving plasma lipid unsaturation in these patients by means of nutritional support should be further investigated.

Adult↗
PubMed2005

[Cox regression analysis on influencing factors of coronary heart disease among people over 40 years of age].

OBJECTIVE: To explore the affecting factors on coronary heart disease among people over 40 years of age in Guangxi area, China. METHODS: Baseline data was gathered through the Third National Blood Pressure Survey in 1991 in China. A total number of 11 818 adults over 40 years old had been studied in Guangxi province. Data of morbidity and mortality of coronary heart disease was obtained. RESULTS: Cardiovascular events were related to systolic blood pressure, diastolic blood pressure, pulse pressure, smoking, BMI regardless of their myocardial infarct (MI) history. Cox regression analysis showed that the relative risk for cardiovascular events increased by 21 [95% confidence interval (CI): 9.06-48.44] times for those people having MI history. When pulse pressure, systolic blood pressure, diastolic blood pressure increased by every 10 mm Hg, the relative risk for cardiovascular events increased by 1.29 (95% CI: 1.11-1.49), 1.18 (95% CI: 1.02-1.22), 1.13 (95% CI: 1.05-1.28) respectively. There was 1.23 (95% Cl: 1.05-1.45) times higher in smoker than non-smoker on relative risk for cardiovascular events. When BMI increasing 1, the relative risk for cardiovascular events would increase 1.03 (95% CI: 1.01-1 .05) times. CONCLUSION: Hypertension, smoking, increase of BMI were the risk factors of coronary heart disease among people who were over 40 years of age.

Adult↗
PubMed1999

Efficacy of continuous hyperthermic peritoneal perfusion for the prophylaxis and treatment of peritoneal metastasis of advanced gastric cancer: evaluation by multivariate regression analysis.

Thirty-two patients with advanced gastric cancer underwent continuous hyperthermic peritoneal perfusion (CHPP) combined with surgery: to prevent peritoneal recurrence in 15 patients without peritoneal metastasis (prophylactic CHPP) and to treat 17 patients with peritoneal metastases (therapeutic CHPP). The postoperative outcome was compared with that of control patients treated with surgery alone. Peritoneal recurrence was less frequent (26%) and the 5-year survival rate was significantly higher (39%) in the patients with prophylactic CHPP than in 40 control patients (42 and 17%, respectively). The patients with therapeutic CHPP showed significantly better median survival than did 20 control patients (11 vs. 6 months). Cox multivariate regression analysis revealed that CHPP was an independent prognostic factor in the prophylactic study (hazard ratio = 0.3965), and that the independent prognostic factor in the therapeutic study was not CHPP but complete resection of the peritoneal metastasis. Thus, CHPP has no marked benefit for established peritoneal metastasis. CHPP for the prevention of peritoneal recurrence may have a beneficial effect on long-term survival, but a prospective randomized trial is needed to clarify its prognostic value.

Adult↗
PubMed2004

Lymph node metastasis as a significant prognostic factor in gastric cancer: a multiple logistic regression analysis.

BACKGROUND: In Japan, the standard treatment policy for all potentially curable patients with gastric cancer is radical resection including extensive lymphadenectomy. This treatment strategy has been used for both early and advanced gastric cancers, and substantial increases in survival time have been reported. In advanced gastric cancer, lymphatic spread is reported to be one of the most relevant prognostic factors for gastric cancer resected for cure. The purpose of this study was to determine the factors affecting lymph node involvement and to establish guidelines for the extent of lymph node dissection most appropriate for the treatment of gastric cancer. METHODS: The clinicopathological features of 926 patients with gastric cancer were reviewed. Information on the clinicopathological features was obtained from the database of gastric cancer at the Department of Gastroenterological Surgery, Sendai National Hospital. Univariate and multivariate analyses of data for patients with gastric cancer tumors were performed to evaluate the prognostic significance of clinicopathological features. The independent risk factors influencing lymph node metastasis were determined by multiple logistic regression analysis. RESULTS: The following clinicopathologic factors were found to be correlated with prognosis of gastric cancer: (1) macroscopic type, (2) depth of invasion, (3) cancer-stromal relationship, (4) histological growth pattern, (5) lymph node involvement, (6) lymphatic invasion, (7) vascular invasion and (8) tumor site. However, a multivariate analysis revealed that macroscopic type, depth of invasion, lymph node involvement and tumor site are independent risk factors for the prognosis of gastric cancer patients. Among these factors, the prognosis of patients with gastric cancer was most strongly influenced by lymph node involvement (odds ratio, 4.632). According to a multiple logistic regression model, depth of cancer invasion and lymphatic invasion was significantly correlated with lymph node metastases. CONCLUSIONS: Lymph node involvement has the strongest influence on the prognosis of gastric cancer. Among the clinicopathological factors, depth of invasion and microscopically lymphatic invasion are important factors in predicting lymph node metastases. Thus, the ability to perform gastrectomy with dissection of lymph nodes is a basic requirement for gastric cancer surgeons.

Adenocarcinoma↗
PubMed2001

Conformation and configuration of tertiary amines via GIAO-derived (13)C NMR chemical shifts and a multiple independent variable regression analysis.

The (13)C chemical shifts of six tertiary amines of unambiguous conformational structure are compared to predicted (13)C NMR chemical shifts obtained via empirically scaled GIAO shieldings for geometries from MM3 molecular mechanics calculations. An average deviation, absolute value of Deltadelta(av), of 0.8 ppm and a maximum deviation, absolute value of Deltadelta(max), of 2.8 ppm between predicted and experimental (13)C shifts of the six tertiary amines of unambiguous structure are found. In several cases of tertiary amines subject to rapid exchange, where experimental (13)C shifts at room temperature are weighted averages of multiple conformers, a comparison of calculated (13)C shifts of all reasonable MM3 predicted conformers with experimental (13)C shifts via a multiple independent variable regression analysis provides an efficient method of determining the major and minor conformers. The examples presented are 2-methyl-2-azabicyclo[2.2.1]heptane and 1,6-diazabicyclo[4.3.1]decane, which each have two expected contributing structures, and 2-(diethylamino)propane and 1,8-diazabicyclo[6.3.1]dodecane, where ten and seven low-energy conformers, respectively, are predicted by MM3 calculations.

Journal Article↗
PubMed2001

Melanin and blood concentration in human skin studied by multiple regression analysis: experiments.

Knowledge of the mechanism of human skin colour and measurement of melanin and blood concentration in human skin are needed in the medical and cosmetic fields. The absorbance spectrum from reflectance at the visible wavelength of human skin increases under several conditions such as a sunburn or scalding. The change of the absorbance spectrum from reflectance including the scattering effect does not correspond to the molar absorption spectrum of melanin and blood. The modified Beer-Lambert law is applied to the change in the absorbance spectrum from reflectance of human skin as the change in melanin and blood is assumed to be small. The concentration of melanin and blood was estimated from the absorbance spectrum reflectance of human skin using multiple regression analysis. Estimated concentrations were compared with the measured one in a phantom experiment and this method was applied to in vivo skin.

Biophysical Phenomena↗