Three-way alternating least squares using three-dimensional tensors in MATLAB®

This paper describes an improved three-way alternating least-squares multivariate curve resolution algorithm that makes use of the recently introduced multi-dimensional arrays of MATLAB®. Multi-dimensional arrays allow for a convenient way to apply chemically sound constraints, such as closure, in the third dimension. The program is designed for kinetic studies on liquid chromatography with diode array detection but can be used for other three-way data analysis. The program is tested with a large number of synthetic data sets and its flexibility is demonstrated, especially when non-trilinear data sets are fit. In this case, the algorithm finds a solution with a better fit than direct trilinear decomposition (DTD). When trilinear data are used, the optimal fit is not as good as when a direct decomposition method is used. Most real data sets, however, have some degree of non-trilinearity. This makes this method a better choice to analyze non-trilinear, three-way data than direct trilinear decomposition.     

Study of the hydrolysis of a sulfonylurea herbicide using liquid chromatography with diode array detection and mass spectrometry by three-way multivariate curve resolution-alternating least squares

This research is focused on the development of a novel, automated chemometric method for obtaining relevant chemical information from time-course measurements of an evolving chemical system. This paper describes an investigation of the hydrolysis of Ally, which is a sulfonylurea herbicide. The hydrolysis of this compound is observed at different pHs and temperatures by reversed-phase liquid chromatography using a diode array detector. The data are analyzed using a three-way, multivariate curve resolution technique. Of special interest was the application of a closure constraint in the kinetic dimension followed by the determination of the rate constants for each step of the pathway by using a differential equation solver and nonlinear fitting of the data.     

Characterization of the polarity of reversed-phase liquid chromatographic stationary phases in the presence of 1-propanol using solvatochromism and multivariate curve resolution

This work characterizes solvation effects in reversed-phase liquid chromatography in the presence of 1-propanol. The solvatochromic method combined with a multivariate curve resolution-alternating least-squares analysis method has been used to characterize two modified silica surfaces--phenyl bonded and C18 bonded silica in mobile-phase mixtures of methanol--water and acetonitrile--water in the presence of 1-propanol. The presence of a small amount of 1-propanol has been shown to affect mainly the polarity properties of the stationary phases while the mobile-phase properties are largely unaffected. The chain collapse mechanism for the C18 stationary phase at higher concentrations of water seems to be inhibited in the presence of 1-propanol, and partitioning is the predominant solute retention mechanism. The phenyl-based phase shows considerably different behavior from that of the C18 phase, and propanol appears to disrupt the pi-stacking interactions between the solute and the phenyl rings anchored to the silica support.     

Comparative study of hydrocarbon, fluorocarbon, and aromatic bonded RP-HPLC stationary phases by linear solvation energy relationships.

The retention properties of eight alkyl, aromatic, and fluorinated reversed-phase high-performance liquid chromatography bonded phases were characterized through the use of linear solvation energy relationships (LSERs). The stationary phases were investigated in a series of methanol/water mobile phases. LSER results show that solute molecular size and hydrogen bond acceptor basicity under all conditions are the two dominant retention controlling factors and that these two factors are linearly correlated when either different stationary phases at a fixed mobile-phase composition or different mobile-phase compositions at a fixed stationary phase are considered. The large variation in the dependence of retention on solute molecular volume as only the stationary phase is changed indicates that the dispersive interactions between nonpolar solutes and the stationary phase are quite significant relative to the energy of the mobile-phase cavity formation process. PCA results indicate that one PCA factor is required to explain the data when stationary phases of the same chemical nature (alkyl, aromatic, and fluoroalkyl phases) are individually considered. However, three PCA factors are not quite sufficient to explain the whole data set for the three classes of stationary phases. Despite this, the average standard deviation obtained by the use of these principal component factors are significantly smaller than the average standard deviation obtained by the LSER approach. In addition, selectivities predicted through the LSER equation are not in complete agreement with experimental results. These results show that the LSER model does not properly account for all molecular interactions involved in RP-HPLC. The failure could reside in the V2 solute parameter used to account for both dispersive and cohesive interactions since "shape selectivity" predictions for a pair of structural isomers are very bad.     

Influence of long-term, low-dose, diuretic-based, antihypertensive therapy on glucose, lipid, uric acid, and potassium levels in older men and women with isolated systolic hypertension: The Systolic Hypertension in the Elderly Program. SHEP Cooperative Research Group

BACKGROUND: Previous studies often of short duration have raised concerns that antihypertensive therapy with diuretics and beta-blockers adversely alters levels of other cardiovascular disease risk factors. METHODS: The Systolic Hypertension in the Elderly Program was a community-based, multicenter, randomized, double-blind, placebo-controlled clinical trial of treatment of isolated systolic hypertension in men and women aged 60 years and older. This retrospective analysis evaluated development of diabetes mellitus in all 4736 participants in the Systolic Hypertension in the Elderly Program, including changes in serum chemistry test results in a subgroup for 3 years. Patients were randomized to receive placebo or treatment with active drugs, with the dose increased in stepwise fashion if blood pressure control goals were not attained: step 1, 12.5 mg of chlorthalidone or 25.0 mg of chlorthalidone; and step 2, the addition of 25 mg of atenolol or 50 mg of atenolol or reserpine or matching placebo. RESULTS: After 3 years, the active treatment group had a 13/4 mm Hg greater reduction in systolic and diastolic blood pressure than the placebo group (both groups, P<.001). New cases of diabetes were reported by 8.6% of the participants in the active treatment group and 7.5% of the participants in the placebo group (P=.25). Small effects of active treatment compared with placebo were observed with fasting levels of glucose (+0.20 mmol/L [+3.6 mg/dL]; P<.01), total cholesterol (+0.09 mmol/L [+3.5 mg/dL]; P<.01), high-density lipoprotein cholesterol (-0.02 mmol/L [-0.77 mg/dL]; P<.01) and creatinine (+2.8 micromol/L [+0.03 mg/dL]; P<.001). Larger effects were seen with fasting levels of triglycerides (+0.9 mmol/L [+17 mg/dL]; P<.001), uric acid (+35 micromol/L [+.06 mg/dL]; P<.001), and potassium (-0.3 mmol/L; P<.001). No evidence was found for a subgroup at higher risk of risk factor changes with active treatment. CONCLUSIONS: Antihypertensive therapy with low-dose chlorthalidone (supplemented if necessary) for isolated systolic hypertension lowers blood pressure and its cardiovascular disease complications and has relatively mild effects on other cardiovascular disease risk factor levels.     

Compensatory increase in common carotid artery diameter. Relation to blood pressure and artery intima-media thickness in older adults. Cardiovascular Health Study

BACKGROUND AND PURPOSE: Common carotid artery (CCA) diameter is thought to increase as a consequence of hypertension and may increase as the thickness of the arterial wall increases. The purpose of this study was to determine CCA dimensions and correlate them with clinical features. METHODS: We performed a cross-sectional, community-based study of adults 65 years of age and older, measuring inner and outer diameter of the CCA in vivo with carotid sonography. Findings were correlated against risk factors for atherosclerosis, CCA intima-media thickness (IMT), and echocardiographically determined left ventricular (LV) mass. RESULTS: Independent variables showing strong positive associations with outer and inner CCA diameter included age, male sex, height, weight, and systolic blood pressure. As an independent variable, LV mass (r = .40 and r = .37, respectively; P < .00001) had a strong positive relation to inner and outer CCA diameters. The relationship between diameter and IMT was different. In a model that controlled for age, sex, and estimated LV mass, an increase of 1 mm in CCA IMT corresponded to a 1.9 mm increase in the outer diameter of the artery (P < .00001) but was not significantly related to the inner diameter (slope = +0.07 mm; P = .26). CONCLUSIONS: Increase in the outer diameter of the CCA is associated with subject size, sex, age, echocardiographically estimated LV mass, and CCA IMT. Increases in internal diameter of the CCA have similar relationships but are not related to IMT. This supports the hypothesis that the human CCA dilates as the thickness of the artery wall increases.     

Characterization of methanol-water and acetonitrile-water association using multivariate curve resolution methods

The solvatochromic comparison method has been used to probe the interactions of solutes with binary solvent mixtures of methanol-water and acetonitrile-water. The solute spectra recorded in these mixtures are composed of the additive spectral contributions of the different solvated species of the solute, i.e., the water-solvated species, the cosolvent-solvated species, and the species solvated by water-solvent complexes. Multivariate curve resolution-alternating least squares has been used to model the solvation of the solutes as a function of the composition of the binary solvent mixture. Spectra and concentration profiles of the dye surrounded by the different solvation environments have been isolated. For the first time, solute spectra solvated exclusively by methanol-water and acetonitrile-water complexes have been obtained, and the solvatochromic parameters of dipolarity/polarizability and hydrogen-bonding acidity have been estimated for these complex species.     

The Fights of Spring: Separation, individuation, and grief in training centers.

Describes the crisis period that occurs in training programs for psychotherapists about midway through each training year, which is often referred to as "February Fight" or "Spring Madness." This crisis contains a wide variety of conflicts within the training institute, ranging from the current struggles of individual members searching for greater autonomy to institutional struggles present since the institute's beginnings. The crisis is viewed as a normal developmental stage in any training year that, when properly understood, may be used to humanize the training institution, further the professional growth of staff and students alike, and facilitate an effective termination of training for the students when the year ends. When not understood and adequately responded to, that same crisis period may prove to be unnecessarily difficult and even detrimental for both staff and students. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Shame and guilt in psychotherapy supervision.

Examines the vulnerability to shame and humiliation of clinical trainees, particularly as it emerges in the course of psychotherapy supervision. It is contended that shame in supervision is generated from 4 major contributing factors: (1) the learning regression, (2) the patient population, (3) the supervisor's management of the supervisory hour, and (4) transference and countertransference in supervision. Suggestions are given for reducing the shame that might compromise the professional well-being of neophyte clinicians and their supervisors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Antihypertensive efficacy of treatment regimens used in Veterans Administration hypertension clinics. Department of Veterans Affairs Cooperative Study Group on Antihypertensive Agents

There is continuing uncertainty about whether morbidity and mortality of treated hypertensive patients depends on the drug(s) used to treat or only on the level of blood pressure achieved. This study was undertaken in a sample of special Veterans Administration hypertension clinics to determine which antihypertensive drugs were selected by the involved healthcare providers and how effective they were in achieving normotension. Hypertensive veterans (n = 6100) were followed in six VA Hypertension Screening and Treatment Program clinics for 46 months beginning in May 1989. Their average age was 60.7 years; 53% lived in the Stroke Belt; 46% had target organ damage, 36% were black, 23% smoked, and 10% had diabetes mellitus. Antihypertensive regimens were divided into 12 all-inclusive categories. Blood pressures were averaged at the last study visit for all patients on a regimen. The regimens of diuretic or diuretic plus beta-blocker gave the lowest average pressures (140.6/82.3 mm Hg) and calcium antagonist the highest (149.0/86.5 mm Hg). ANOVA indicated that differences between seven common regimens and also between the four single drug regimens were highly significant (P<.0001). This pattern of low treated pressure with the "old" agents and higher treated pressure with newer agents was reflected in the percentage of patients controlled below 140/90 mm Hg and the percentage uncontrolled above 159/94 mm Hg. Blacks and patients with target organ damage resembled the entire cohort in average treated diastolic blood pressure, but the former had lower and the latter had higher treated systolic blood pressure than the entire cohort.