In this paper we describe block algorithms for the reduction of a real symmetric matrix to tridiagonal form and for the reduction of a general real matrix to either bidiagonal or Hessenberg form using Householder transformations. The approach is to aggregate the transformations and to apply them in a blocked fashion, thus achieving algorithms that are rich in matrix-matrix operations. These red...

The relation between intra-abdominal visceral fat accumulation and blood pressure was investigated in 67 obese women (mean body mass index, 33.6 +/- 3.1; average age, 50 +/- 11 years). As an index of intra-abdominal fat accumulation, the ratio of the intra-abdominal visceral fat area to subcutaneous fat area was determined using a computed tomographic section at the level of the umbilicus. When...

Many studies have used ratios based on intercaudate distance as a measure of caudate atrophy and ratios based on bifrontal distance as a measure of ventricular enlargement independent of caudate atrophy. The purpose of the current study was to determine to what extent these ratios correlate with caudate area and volume and frontal horn area in various groups of patients. The three linear ratio ...

TO THE EDITOR: The review by Grimes (1) of the history of nomograms was informative. However, his criticism of the “epidemic” of nomogram resurgence was fundamentally unsubstantiated. Grimes states that “nomograms provided speed in calculation at the cost of precision” without providing any evidence that the lost precision mattered. Where is the evidence, for example, that calculating likelihoo...

in this study, the effects of long term use of urban wastewater (over 40 years) on soil salt content and related parameters were evaluated in the lands south of tehran. for this analysis, kriging methods were tested. according to the suitable model indices, ordinary kriging (ok) was suitable for ph, clay, na+, mg2+ and sodium adsorption ratio (sar) interpolation; log-normal kriging (log-normal ...

BACKGROUND Research is needed to determine the prevalence and variables associated with the diagnosis of flatfoot, and to evaluate the validity of three footprint analysis methods for diagnosing flatfoot, using clinical diagnosis as a benchmark. METHODS We conducted a cross-sectional study of a population-based random sample ≥ 40 years old (n = 1002) in A Coruña, Spain. Anthropometric variabl...

OBJECTIVES The purpose of this study was to compare the screening efficiency for Down syndrome using likelihood ratios versus logistic regression coefficients. METHODS We conducted a retrospective study of women at increased risk for Down syndrome referred for a second-trimester genetic sonogram. Likelihood ratios were calculated by multiplying the risk ratio from maternal serum screening by ...

PURPOSE To develop a fully automated algorithm (AP) to perform a volumetric measure of the optic disc using conventional stereoscopic optic nerve head (ONH) photographs, and to compare algorithm-produced parameters with manual photogrammetry (MP), scanning laser ophthalmoscope (SLO) and optical coherence tomography (OCT) measurements. METHODS One hundred twenty-two stereoscopic optic disc pho...