Partition Values Research Articles

A controlled experiment on white-box database testing

Controlled experiments are a powerful way to assess and compare the effectiveness of different techniques. In this paper we present the experimental results of the evaluation of the effectiveness of a structural test coverage criterion developed for SQL queries when used by a tester to guide the selection of database test cases. We describe a controlled experiment designed for comparing this criterion with other conventional criteria such as equivalence partitioning and boundary value analysis. The results show that 1) the use of the structural coverage allows the tester to develop more effective test cases, 2) the effectiveness is higher when considering the kind of faults that are more specifically related to SQL than other kinds of faults, and 3) the results give us some insight into how to improve the coverage criterion.

Finite element thermal analysis of micro-EDM

A finite element-based thermal model for the Micro Electro-Discharge Machining (µ-EDM) is developed for the determination of temperature distribution in the zone of influence of single spark. The model is able to predict the shape and size of the crater that is formed by single spark as a result of the material removal. The calculated crater radius result is verified by comparing them with experimental results available in literature. Energy partition is also determined using computational experiments. Parametric study for crater radius, crater depth, Material Removal Rate (MRR) and energy partition has been also done. It has been found that heat flux and input energy significantly affect energy partition value.

Thermal Study in Diamond Grinding of Zirconia

In the present study, zirconia ceramic was ground with a resin-bonded diamond wheel on a precision surface grinding machine. Grinding temperatures generated at the wheel-workpiece contact zone were measured using a sandwiched foil thermocouple, and the net consumed grinding powers were also measured. The energy partition to the diamond abrasives was estimated using measured grinding temperatures and powers. Based on the energy partition values obtained from the analyzed results, the diamond tip temperature was calculated and found to be over 1000°C if the circular grain contact of radius was less than a critical value for ductile field grinding of zirconia ceramic.

Abstract 1585: Echocardiographic Left Ventricular Volumes are Optimally Indexed to Fat Free Mass to Adjust for Differences in Body Size

Introduction Echocardiographic left ventricular (LV) size and structure are commonly indexed to body surface area (BSA) to adjust for body size. However, BSA may not be the optimal variable to adjust measurements to. While previous studies have demonstrated that the best determinant of LV mass is fat free mass (FFM), the relationship of LV volumes with body composition is uncertain. Objectives To determine the relationships between LV size and body composition. Methods Normal subjects (Caucasian, Maori, Samoan, Chinese and Indian ethnicity) free of cardiac disease underwent medical history, ECG, blood test (cholesterol/glucose), echocardiography for LV volumes (2D biplane methods of discs) and DEXA scans (body composition). Results 166 subjects were assessed: 96 (56%) were women, median age 26yrs, mean BMI 25.4 (SD 6.0), BSA 1.85m 2 (SD 0.28), LVEDV 88ml (SD 27), LVESV 33ml (SD 14). Significant correlations were observed between LV size and measures of body size in all ethnic groups. However, FFM was the best independent predictor of LV volumes (LVEDV partial R 2 0.48 – 0.60). Body size was smallest among Asian subjects and highest among Maori & Samoan subjects. A significant difference in unindexed LVEDV was observed across the groups which persisted when indexed to BSA or height (all P<0.01). However, when LVEDV was indexed to FFM the ethnic differences were reduced (figure ). Conclusions Among normal subjects LV size is strongly related to FFM. Indexing LV volumes to FFM largely eliminated the differences in LVEDV between subjects with varying body composition. Reference and partition values for normal LV size should be based on LV volumes indexed to fat free mass.

Quantifying garnet-melt trace element partitioning using lattice-strain theory: assessment of statistically significant controls and a new predictive model

As a complement to our efforts to update and revise the thermodynamic basis for predicting garnet-melt trace element partitioning using lattice-strain theory (van Westrenen and Draper in Contrib Mineral Petrol, this issue), we have performed detailed statistical evaluations of possible correlations between intensive and extensive variables and experimentally determined garnet-melt partitioning values for trivalent cations (rare earth elements, Y, and Sc) entering the dodecahedral garnet X-site. We applied these evaluations to a database containing over 300 partition coefficient determinations, compiled both from literature values and from our own work designed in part to expand that database. Available data include partitioning measurements in ultramafic to basaltic to intermediate bulk compositions, and recent studies in Fe-rich systems relevant to extraterrestrial petrogenesis, at pressures sufficiently high such that a significant component of majorite, the high-pressure form of garnet, is present. Through the application of lattice-strain theory, we obtained best-fit values for the ideal ionic radius of the dodecahedral garnet X-site, r0(3+), its apparent Young’s modulus E(3+), and the strain-free partition coefficient D0(3+) for a fictive REE element J of ionic radius r0(3+). Resulting values of E, D0, and r0 were used in multiple linear regressions involving sixteen variables that reflect the possible influence of garnet composition and stoichiometry, melt composition and structure, major-element partitioning, pressure, and temperature. We find no statistically significant correlations between fitted r0 and E values and any combination of variables. However, a highly robust correlation between fitted D0 and garnet-melt Fe–Mg exchange and DMg is identified. The identification of more explicit melt-compositional influence is a first for this type of predictive modeling. We combine this statistically-derived expression for predicting D0 with the new expressions for predicting E and r0 outlined in the first of our pair of companion papers into an updated set of formulae that use easy-to-measure quantities (e.g. garnet composition, pressure, temperature) to predict variations in E, r0, and D0. These values are used in turn to calculate D values for those garnets. The updated model substantially improves upon a previous model (van Westrenen et al. in Contrib Mineral Petrol 142:219–234, 2001), and accounts well for trivalent cation partitioning in nominally anhydrous systems up to at least 15 GPa, including for eclogitic bulk compositions and for Fe-rich systems appropriate to magmagenesis on the Moon and Mars. The new model is slightly less successful in predicting partitioning with strongly majoritic garnets, although the mismatch is much less than with the original 2001 model. Although it also improves upon the 2001 model in predicting partitioning in hydrous systems, the mismatch between model and observation is still unacceptably large. The same statistical tools were applied in an attempt to predict tetravalent partitioning as well, because lattice-strain based techniques are not applicable to such partitioning. However, no statistically significant predictive relationships emerged from that effort. Our analyses show that future efforts should focus on filling the gap in partitioning data between ∼10 and 25 GPa to evaluate more closely the gradual transition of garnet to majorite, and on systematically expanding the hydrous partitioning database to allow extension of our model to water-bearing systems.

Left ventricular hypertrophy: beyond the image and defining the human cardiac phenotype in hypertension

IntroductionLeft ventricular hypertrophy (LVH) has proven to be a very useful risk marker in hypertension. It indicates a higher risk of cardiovascular events and particularly sudden death [1,2]. It defines the effects of hypertension on an important target organ, the heart, and is one step along th

Ethyl Hexanoate Transfer Modeling in Carrageenan Matrices for Determination of Diffusion and Partition Properties

Aroma compound properties in food matrices, such as volatility and diffusivity, have to be determined to understand the effect of composition and structure on aroma release and perception. This work illustrates the use of mass transfer modeling to identify diffusion and partition properties of ethyl hexanoate in water and in carrageenan matrices with various degrees of structure. The comparison of results obtained with a diffusive model to those obtained with a convective model highlights the importance of considering the appropriate transfer mechanism. Modeling of the preliminary experimental steps ensures correct estimation of the conditions for the main aroma release step. The obtained values of partition and diffusion coefficients are in agreement with those found in the literature (either experimentally determined or predicted by theoretical equations) and demonstrate that the structure level of carrageenan matrices has little influence on diffusion properties of ethyl hexanoate (less than 20%).

Use of BNP and CRP as Biomarkers in Assessing Cardiovascular Disease:Diagnosis Versus Risk

Biomarkers are used in medicine to facilitate diagnosis, assess risk, direct therapy and determine efficacy of treatment. Sensitivity and specificity are essential in order for a biomarker to be useful. Brain natriuretic peptide (BNP) and C-reactive protein (CRP) are considered biomarkers of cardiovascular disease. However, they differ in function, sensitivity and specificity. BNP is released from the myocardium in response to myocardial stretch, a clear cause and effect relationship; therefore, it is useful in the diagnosis of heart failure when patients present with dyspnea of unknown origin and to assess treatment in high risk patients with diagnosed heart failure. Sex and age based reference ranges and partition values are established from clinical trials and from populations screened for the absence of cardiovascular disease. Highly sensitive and reproducible methods are also available to measure CRP. However, although CRP is associated with adverse cardiovascular events, unlike BNP, multiple stimuli increase production of CRP. Therefore, elevation in CRP is not specific to cardiovascular disease. Partition values for CRP and cardiovascular risk based on epidemiological studies predict risk for populations but may not always be useful when used alone to predict individual risk or to direct therapy. Given the non-specific stimuli which affect circulating concentrations of CRP, using CRP to monitor treatment to reduce cardiovascular risk may provide little benefit without understanding or targeting the underlying causes for its elevation.

Crystal–melt partitioning of noble gases (helium, neon, argon, krypton, and xenon) for olivine and clinopyroxene

Mineral–melt partition coefficients of all noble gases ( min/melt D i ) have been obtained for olivine (ol) and clinopyroxene (cpx) by UV laser ablation (213 nm) of individual crystals grown from melts at 0.1 GPa mixed noble gas pressure. Experimental techniques were developed to grow crystals virtually free of melt and fluid inclusions since both have been found to cause profound problems in previous work. This is a particularly important issue for the analysis of noble gases in crystals that have very low partition coefficients relative to coexisting melt and fluid phases. The preferred partitioning values obtained for the ol–melt system for He, Ne, Ar, Kr, and Xe are 0.00017(13), 0.00007(7), 0.0011(6), 0.00026(16), and 0.0006 ( - 6 ) ( + 9 ) , respectively. The respective cpx–melt partition coefficients are 0.0002(2), 0.00041(35), 0.0011(7), 0.0002(2), and 0.0002 ( - 2 ) ( + 3 ) . The data confirm the incompatible behaviour of noble gases for both olivine and clinopyroxene but unlike other trace elements these values show little variation for a wide range of atomic radius. The lack of dependence of partitioning on atomic radius is, however, consistent with the partitioning behaviour of other trace elements which have been found to exhibit progressively lower dependence of min/melt D i on radius as the charge decreases. As all noble gases appear to exhibit similar min/melt D i values we deduce that noble gases are not significantly fractionated from each other by olivine and clinopyroxene during melting and fractional crystallisation. Although incompatible, the partitioning values for noble gases also suggest that significant amounts of primordial noble gases may well have been retained in the mantle despite intensive melting processes. The implication of our data is that high primordial/radiogenic noble gas ratios ( 3He/ 4He, 22Ne/ 21Ne, and 36Ar/ 40Ar) characteristic of plume basalt sources can be achieved by recycling a previously melted (depleted) mantle source rather than reflecting an isolated, non-degassed primordial mantle region.

Contrast Administration Reduces Interobserver Variability in Determination of Left Ventricular Ejection Fraction in Patients With Left Ventricular Dysfunction and Good Baseline Endocardial Border Delineation

Echocardiographic contrast agents improve endocardial border delineation in patients with technically difficult baseline studies. With medical and device therapy for heart failure increasingly based on left ventricular (LV) ejection fraction (EF) partition values, the accurate and reproducible assessment of LV function is necessary. It was hypothesized that routine contrast enhancement would significantly reduce interobserver variability in the determination of LVEFs in a cohort of patients with LV dysfunction and good baseline endocardial delineation. All patients underwent baseline noncontrast studies followed by contrast-enhanced imaging using Definity. Two experienced echocardiographers, blinded to the clinical data, determined LVEFs using 4 different techniques: noncontrast estimated (NCE), noncontrast calculated (NCC), contrast estimated (CE), and contrast calculated (CC). Using a mixed-model procedure that allows for fixed and random events, the variance due to error and that due to the patient was obtained (interclass correlation). The proportion of variation due to the reader was calculated as 1--interclass correlation. Mean standardized percentage differences ([reader 1 EF--reader 2 EF]/mean EF) were also calculated for each method. The proportion of variation due to the reader was smallest in the CC group and largest in the NCC group (NCE = 0.21, NCC = 0.33, CE = 0.25, CC = 0.11). The results were similar when only patients with NCE EFs >or=20% and <or=50% were analyzed (NCE = 0.29, NCC = 0.47, CE = 0.33, CC = 0.15). The mean standardized percentage difference between readers was smallest in the CC group for all patients and for those with NCE EFs >or=20% and <or=50%. In conclusion, contrast administration reduces interobserver variability in LVEF assessment, even in patients with good baseline endocardial border delineation, and should be used routinely regardless of the perceived adequacy of baseline images, especially if the LVEF is >or=20% and <or=50%.

Gender Differences in Left Ventricular Systolic Function in American Indians (from the Strong Heart Study)

Data from population-based studies indicate that men have a higher incidence and worse prognoses of congestive heart failure than women. Echocardiography was used to compare left ventricular (LV) myocardial and chamber contractility between 490 male and 861 female American Indian participants in the second Strong Heart Study examination. After adjusting for fat-free mass, baseline hypertension, diabetes mellitus, coronary heart disease, and alcohol consumption, LV ejection fractions were higher in women than men (66 +/- 8% vs 63 +/- 9%, p = 0.002), as were stress-corrected mid-wall shortening (106 +/- 13% vs 104+/-15%, p = 0.006) and the circumferential end-systolic stress/end-systolic volume index (7.1 x 10(4) +/- 1.9 x 10(4) vs 6.5 x 10(4) +/- 2.1 x 10(4) kdyne/cm3, all p values <0.001). LV ejection fractions were less than the predefined partition value in 4.7% of women and in 16.7% of men (odds ratio 0.25, 95% confidence interval 0.18 to 0.34, p <0.001). Stress-corrected mid-wall shortening was less than the predetermined lower limit of normal in 2.9% of women and in 6.2% of men (odds ratio 0.45, 95% confidence interval 0.29 to 0.70, p <0.001). There was no significant gender difference in supranormal function by either measure of LV systolic function. Estimated mean independent effects of female gender were a 3% greater ejection fraction, 2.7% greater stress-corrected mid-wall shortening, and a 0.4 x 10(4) kdyne/cm3 greater circumferential end-systolic stress/end-systolic volume index. In conclusion, in a population-based sample aged 45 to 74 years, women had greater LV myocardial and chamber function than men. Gender-specific partition values for measures of LV systolic function may be necessary to detect abnormal contractility in clinical and epidemiologic studies.

Partition coefficient of migrants in food simulants/polymers systems

Partition coefficients of six migrants (ethyl acetate, acetaldehyde, acetonitrile, methyl ethyl ketone, isopropyl acetate and butyraldehyde) were determined between four food simulants (water, 10% ethanol, 3% acetic acid and 95% ethanol) and two polymers (polyamide and polyethylene terephthalate). The results showed that partition coefficient is highly dependent on the nature of the migrant, polymer and food simulant. Of the six migrants, acetonitrile and ethyl acetate had the highest affinity for polar food simulants such as water, 10% ethanol and 3% acetic acid. Partition values for systems containing 95% ethanol as a food simulant were higher for non-polar migrants and lower for polar migrants.

Seasonal Changes in Dry Matter Partitioning, Yield, and Crude Protein of Intermediate Wheatgrass and Smooth Bromegrass

Seasonal patterns of dry matter partitioning and nutritive value of leaf and stem components of grass species is important for selecting species for planting, planning grazing strategies, and making management decisions. Our objective was to compare dry matter yield and crude protein (CP) yield of blade, sheath, and stem fractions of intermediate wheatgrass [Elytrigia intermedia (Host) Nevski] and smooth bromegrass (Bromus inermis Leyss.) during the growing season. Intermediate wheatgrass and smooth bromegrass were sampled on a weekly basis from 14 May to 25 June in 1997 and from 5 May to 23 June in 1998 at Lincoln, NE. Samples were separated into blade, sheath, stem, and inflorescence components and yield and concentration of CP were determined. Smooth bromegrass tended to have greater blade and stem yield than intermediate wheatgrass during the 1997 and 1998 sampling periods. Yield of sheath was similar between species. Crude protein yield of blade and stem was also greater for smooth bromegrass than intermediate wheatgrass in both years. Sheath CP yield was greater for intermediate wheatgrass in 1998. Both species followed a similar pattern of dry matter accumulation; however, intermediate wheatgrass dry matter accumulation, especially stem, tended to be 1 to 2 wk behind smooth bromegrass. Differences in dry matter partitioning, yield, and CP in these two species illustrates the advantages having a complement of forage species. Choosing a diversity of species with differing growth habits would be beneficial for improving the distribution of forage yield and quality to match the seasonal demand of grazing livestock.

11.3.3 Enabling Measurement‐Driven System Development by Analyzing Testing Strategy Tradeoffs

ABSTRACTMeasurement‐driven system development focuses on using quantitative data to evaluate capabilities, benefits, progress, and tradeoffs as well as identify improvement opportunities. This paper describes a controlled study that addresses software testing effectiveness and focuses on the combination of individual testing techniques into team‐based testing strategies. This analysis is intended to enable measurement‐driven process improvement by characterizing how testing effectiveness relates to several factors, including testing strategy, software type, and developer expertise. In this study, a representative group of software development professionals applied common testing techniques to different types of software. This study compares the six possible team combinations of three testing techniques: (1) code reading by stepwise abstraction, (2) functional testing using equivalence partitioning and boundary value analysis, and (3) structural testing using 100% statement coverage criteria. Thirty‐two professional developers applied the techniques to three unit‐sized programs in a fractional factorial experimental design.The major results of this study are the following. The six combined testing strategies detected 17% more of the programs' faults on the average than did the three single techniques, which was a 35% improvement in fault detection. The highest percentages of the programs' faults were detected when there was a combination of either two code readers or a code reader and a functional tester. However, a pairing of two code readers detected more faults per hour than did a pairing of a code reader and a functional tester. The pairing of two individuals of advanced expertise resulted in the highest percentage of faults being detected. The most cost‐effective (number of faults detected per hour) testing strategy overall was when code reading was applied by an individual. The most cost‐effective combined testing strategy was when a code reader was paired with either another code reader or a structural tester. Both the percentage of faults detected and the fault detection cost‐effectiveness depended on the type of software being tested. In conclusion, we outline future research directions that build on these strategies and ideas.

Sampling in the Smear Zone: Evaluation of Nondissolved Bias and Associated BTEX, MTBE, and TPH Concentrations in Ground Water Samples*

AbstractAt fuel release sites, source zone characterization and monitoring for benzene, toluene, ethylbenzene and xylenes, methyl‐tert‐butyl‐ether, and total petroleum hydrocarbons as gasoline (TPHg) typically involve interpreting ground water data from grab (screening) samples and/or monitoring wells within the “smear zone,” where the soil pores contain both separate‐phase petroleum and dissolved‐phase constituents. Because the samples are collected within the smear zone, the ground water concentrations can be biased high by contributions from entrained nondissolved petroleum. The nondissolved bias is often not recognized by data users and can lead to erroneous interpretations and inputs for fate and transport modeling, mass flux calculations, risk assessments, etc., which can result in increased requirements for remediation or increased claims for damages in litigation. Ground water sample concentrations can be evaluated for potential bias by nondissolved petroleum using a phased approach that begins with comparison of the data to effective solubility concentrations for ethylbenzene, xylenes, and TPH derived from laboratory partitioning studies using fresh fuels. To reflect the reduction in effective solubility that results from weathering of the source, the ground water sample concentrations can also be compared to concentrations for samples that were collected with entrained sheen. In this data set of 47 gasoline release sites, the frequency of nondissolved bias in the reported ground water monitoring data ranged from 0.4% to 86%, depending on which concentration criterion was used as an indicator. If exceedances of the average concentration values for the laboratory partitioning and the sheen data are used, the frequency ranged from 9% to 20%. Also, reproducibility for duplicates collected from monitoring wells in the smear zone was unacceptable more than half of the time. This evaluation shows that a significant percentage of ground water monitoring data collected from the smear zone is unreliable for characterizing dissolved concentrations of petroleum constituents.

Echocardiographic partition values and prevalence of left ventricular hypertrophy in hypertensive Nigerians.

BackgroundLeft ventricular hypertrophy (LVH) is a well known independent risk factor for cardiovascular events. It has been shown that combination of left ventricular mass (LVM) and relative wall thickness (RWT) can be used to identify different forms of left ventricular (LV) geometry. Prospective studies have shown that LV geometric patterns have prognostic implications, with the worst prognosis associated with concentric hypertrophy. The methods for the normalization or indexation of LVM have also recently been shown to confer some prognostic value especially in obese population. We sought to determine the prevalence of echocardiographic lLVH using eight different and published cut-off or threshold values in hypertensive subjects seen in a developing country's tertiary centre.MethodsEchocardiography was performed in four hundred and eighty consecutive hypertensive subjects attending the cardiology clinic of the University college Hospital Ibadan, Nigeria over a two-year period.ResultsComplete data was obtained in 457 (95.2%) of the 480 subjects (48.6% women). The prevalence of LVH ranged between 30.9–56.0%. The highest prevalence was when LVM was indexed to the power of 2.7 with a partition value of 49.2 g/ht2.7 in men and 46.7 g/ht2.7 in women. The lowest prevalence was observed when LVM was indexed to body surface area (BSA) and a partition value of 125 g/m2 was used for both sexes. Abnormal LV geometry was present in 61.1%–74.0% of our subjects and commoner in women.ConclusionThe prevalence of LVH hypertensive patients is strongly dependent on the cut-off value used to define it. Large-scale prospective study will be needed to determine the prognostic implications of the different LV geometry in native Africans.

High-pressure phase equilibria and element partitioning experiments on Apollo 15 green C picritic glass: Implications for the role of garnet in the deep lunar interior

We report results of nominally anhydrous near-liquidus experiments on a synthetic analog to very low-titanium Apollo 15 green C lunar picritic glass from ∼2 to 5 GPa. Apollo 15 green C glass (A15C) is saturated with garnet and pyroxene on the liquidus at ∼3 GPa. However, such an assemblage is unlikely to represent the lunar-mantle source region for this glass, and instead an olivine + orthopyroxene-dominated source is favored, in accord with earlier lower-pressure experiments on A15C. Near-liquidus garnet has a slight but significant majorite component at ∼5 GPa in this iron-rich bulk composition, as expected from our previous work in ordinary-chondritic bulk compositions. Ion microprobe measurements of partitioning of Sr, Ba, Sc, Nd, Sm, Dy, Yb, Y, Zr, Hf, and Th between garnet and coexisting melt in these experiments are the first garnet partition coefficients ( D values) available that are directly relevant to lunar compositions. D values for these garnets differ significantly compared to D values for garnets grown in more magnesian, terrestrial bulk compositions, which until now are all that have been available in modeling the possible role of garnet in the lunar interior. For example, D values for heavy rare earth elements are lower than are those from terrestrial basaltic systems. These partitioning values are well-described by the lattice-strain partitioning model, but predictive relationships for garnet partitioning using that model fail to match the measured values, as was the case in our earlier work on chondritic compositions. Using our new D values in place of the “terrestrial” values in a variety of models of lunar petrogenesis, we suggest that garnet is unlikely to be present in the source regions for very titanium-poor lunar liquids despite its appearance on the liquidus of A15C.

Air to brain, blood to brain and plasma to brain distribution of volatile organic compounds: linear free energy analyses

Partition coefficients, K brain, for volatile organic compounds, VOCs, from air to brain have been collected for 81 compounds (air to human brain and air to rat brain). For the 81 VOCs a linear free energy equation (LFER) correlates log K brain with R 2 = 0.923 and S.D. = 0.346 log units. Use of training and test sets gives a predictive assessment of 0.35–0.40 log units. Combination of log K brain with our previously listed values of log K blood enables blood to brain partition, as log P b-brain, to be obtained for 78 VOCs. These values can be correlated with R 2 = 0.725 and S.D. = 0.203 log units; use of training and test sets allows a predictive assessment for log P b-brain of 0.16–0.20 log units. Values for air to plasma were available for 21 VOCs. When these data were combined with the data on air to blood and air to brain, values for partition between (blood or plasma) to brain, P bp-brain, were available for 99 VOCs. A LFER correlates this data with R 2 = 0.703 and S.D. = 0.197 log units; use of training and test sets allows a predictive assessment for log P bp-brain of 0.15–0.20 log units.

Methyl‐Hydroxypyridinecarboxylic Acids as Possible Bidentate Chelating Agents for Aluminium(III): Synthesis and Metal–Ligand Solution Chemistry

AbstractIn view of a possible application to aluminium chelation therapy, 1‐methyl‐3‐hydroxy‐4‐pyridinecarboxylic acid (1M3H4P) and 1‐methyl‐4‐hydroxy‐3‐pyridinecarboxylic acid (1M4H3P) were synthesized, and their chemical interactions with aluminium(III) were investigated in aqueous 0.6 m (Na)Cl at 25 °C by means of potentiometric titrations. The qualitative and quantitative results obtained were confirmed by UV spectrophotometry and 1H NMR spectroscopy. For both ligands, the species AlL2+, AlL2+, AlL3, and AlL2H–1 were identified, with logβ1,1,0 = 7.66, logβ1,2,0 = 14.27, logβ1,3,0 = 19.099, and logβ1,2,–1 = 7.00 for 1M3H4P, logβ1,1,0 = 7.21, logβ1,2,0 = 13.41, logβ1,3,0 = 18.15, and logβ1,2,–1 = 6.4 for 1M4H3P. The chelation strength of 1M3H4P and 1M4H3P is lower than that of other available aluminium(III) chelators, e.g. deferiprone (pAl difference at physiological pH: ca. 3 log units). The octanol/aqueous partitioning values of 1M3H4P and 1M4H3P were 0.0054 and 0.0015, respectively, showing high hydrophilicity. The efficiencies of the ligands to chelate aluminium(III) were evaluated at physiological pH and ion strength “in vitro”. 1M3H4P and 1M4H3P were more effective than their non‐methylated analogs 3H4P and 4H3P. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2006)

Left atrial diameter as an independent predictor of first clinical cardiovascular events in middle-aged and elderly adults: The Strong Heart Study (SHS)

Echocardiographic left atrial (LA) volume has been documented to be an independent predictor of cardiovascular events. Less is known about the predictive ability of anteroposterior LA diameter, a simpler measure of LA size obtained routinely during echocardiographic evaluation. We investigated the prognostic value of LA diameter for incident cardiovascular events in 2804 American Indians free of clinical cardiovascular disease, valvular disease, and atrial fibrillation. Echocardiographic variables were obtained using standardized methods, and previously derived sex-specific partition values were used to define left ventricular (LV) hypertrophy indexed to height(2.7) (in meters) and LA enlargement (> 4.2 cm in men, > 3.8 cm in women). Cardiovascular events included nonfatal stroke, coronary heart disease, congestive heart failure, and fatal cardiovascular disease based on validated definitions. During a median follow-up of 7 years, 368 events occurred. LA diameter, both as a continuous and as a categorical variable, was significantly associated with incident cardiovascular events in unadjusted analyses. In multivariable analyses that adjusted for age, sex, body mass index, hypertension, diabetes, total cholesterol-high-density lipoprotein cholesterol, smoking, renal insufficiency, LV hypertrophy, abnormal LV systolic and diastolic function, mitral annular calcification, fibrinogen, and C-reactive protein, both LA diameter (risk ratio 1.04/mm, 95% CI 1.02-1.07, P < .002) and LA enlargement (risk ratio 1.57, 95% CI 1.17-2.10, P = .002) remained independent predictors of first cardiovascular events. In this population-based cohort, LA diameter independently predicted incident cardiovascular events after adjustment for established clinical, echocardiographic, and inflammatory risk factors. This simple measure of LA dilatation can identify individuals at heightened risk who may warrant more aggressive risk factor modification.