Ferguson Method Research Articles

Estimation of loss reserves with lognormal development factors

This paper uses a development technique to estimate the loss reserve in a classical run-off triangle setting. Closed-form solutions for unbiased estimates of reserves and their corresponding standard errors can be obtained by assuming lognormal distributions of the development factors. The technique is applied to the Bornhuetter–Ferguson method [Bornhuetter, R.L., Ferguson, R.E., 1972. The actuary and IBNR. Proc. Casualty Actuarial Soc. 59, 181–195] and to two previously studied data sets.

The Unstructured N-terminal Tail of ParG Modulates Assembly of a Quaternary Nucleoprotein Complex in Transcription Repression

ParG is the prototype of a group of small (<10 kDa) proteins involved in accurate plasmid segregation. The protein is a dimeric DNA binding factor, which consists of symmetric paired C-terminal domains that interleave into a ribbon-helix-helix fold that is crucial for the interaction with DNA, and unstructured N-terminal domains of previously unknown function. Here the ParG protein is shown to be a transcriptional repressor of the parFG genes. The protein assembles on its operator site initially as a tetramer (dimer of dimers) and, at elevated protein concentrations, as a pair of tetramers. Progressive deletion of the mobile N-terminal tails concomitantly decreased transcriptional repression by ParG and perturbed the DNA binding kinetics of the protein. The flexible tails are not necessary for ParG dimerization but instead modulate the organization of a higher order nucleoprotein complex that is crucial for proper transcriptional repression. This is achieved by transient associations between the flexible and folded domains in complex with the target DNA. Numerous ParG homologs encoded by plasmids of Gram-negative bacteria similarly are predicted to possess N-terminal disordered tails, suggesting that this is a common feature of partition operon autoregulation. The results provide new insights into the role of natively unfolded domains in protein function, the molecular mechanisms of transcription regulation, and the control of plasmid segregation.

Rapid Determination of Protein Molecular Weight by the Ferguson Method and Multiplexed Capillary Electrophoresis

A method based on the use of the Ferguson method and multiplexed sodium dodecyl sulfate-capillary gel electrophoresis (SDS-CGE) with UV detection was demonstrated for the rapid determination of molecular weights of proteins. The method employs a capillary array where different uncoated capillaries are filled with gel buffers containing different concentrations of poly(ethylene oxide) (PEO). All data required to construct Ferguson plots and universal calibration curves for the determination of the molecular weights of diverse types of proteins are generated simultaneously in an eight-capillary array within 20 min.

Thoracic kyphosis and the prevalence of advanced uterine prolapse

To determine if there is an association between the degree of thoracic kyphosis and the prevalence of advanced uterine prolapse in women. A retrospective case-control study compared the degree of thoracic kyphosis among white women with advanced uterine prolapse with that of matched controls. Medical records were reviewed for 412 consecutive women who underwent either abdominal or vaginal hysterectomy. The cases were those with uterine prolapse to or beyond the level of the introitus, and women with no evidence of prolapse served as controls. Spinal curvature was measured preoperatively for each patient using a lateral chest x-ray and the Ferguson method. Forty-eight cases were matched to 48 controls for age, weight, menopausal status, and hormonal status. Results were stratified to analyze the effect of parity on the relationship between uterine prolapse and thoracic kyphosis. The degree of thoracic kyphosis was higher in patients with uterine prolapse than in controls (mean paired difference = 4.9 degrees, 95% confidence interval [CI] 3.1-6.7; P < .001). Patients with uterine prolapse had a mean spinal curvature of 13.0 degrees (95% CI 11.5-14.5), whereas controls had one of 8.1 degrees (95% CI 6.9-9.4). A higher degree of thoracic kyphosis was associated with an incremental higher occurrence of uterine prolapse (odds ratio 1.35, 95% CI 1.11-1.65; P < .01). Thoracic kyphosis appears to be associated with uterine prolapse.

DNA binding specificity of the Mu Ner protein.

Binding of purified phage Mu Ner protein to a series of DNA fragments was investigated in order to determine the length requirements for tight specific binding. Gel retardation experiments with wild-type 307 base pair (bp) Mu DNA and shorter, synthetic oligonucleotides were performed, and apparent dissociation constants (KappD) were determined from the half-saturation point. While Ner formed four complexes with the 307 bp DNA fragment, only one complex was observed with the shorter DNAs. The 50 and 30 bp fragments had KappD values of 5 and 20 nM, respectively. Ner binding was progressively weaker with decreasing size of the DNA fragments, with no binding observed for 12mers. The shortest DNA fragments which bound well were two 18 bp fragments for which KappD values were in the range of 50-100 nM. The stoichiometry of Ner complexes with the 30 and 18 bp fragments was determined using a modified Ferguson method. Ner was found to form a tetramer on the 30 bp DNA and a dimer on the 18 bp DNA, which makes the latter a good candidate for the study of a Ner-DNA complex by NMR. In order to clarify which DNA regions were important for Ner-DNA binding, hydroxyl radical footprinting was performed for a range of Ner concentrations from 30 to 500 nM. The footprint revealed that Ner contacts the DNA backbone every 12-13 bp, on both strands of the DNA. The order in which protected regions appeared with increasing protein concentration indicated that two Ner monomers bound to DNA simultaneously. A model of Ner binding to DNA is proposed on the basis of these results.

Capillary sodium dodecyl sulfate gel electrophoresis of proteins II. On the Ferguson method in polyethylene oxide gels

Capillary sodium dodecyl sulfate (SDS) gel electrophoresis is demonstrated to be a powerful new analytical method for the separation of protein molecules based on their molecular mass. Standard curves of logarithm molecular mass versus reciprocal relative migration time give the estimated molecular mass of sample proteins within the acceptable 10% error for most proteins. Larger errors are possible, however, when special groups such as carbohydrates (glycoproteins) or lipids (lipoproteins) are present due to a different ratio of binding SDS molecules. An automated Ferguson method is shown that corrects for this non-ideal behavior in capillary SDS-polyethylene oxide gel electrophoresis.

A three-way credibility approach to loss reserving

Two ways of estimating ultimate incurred losses are loss based and exposure based. The former uses a factor applied to losses emerged to date; the latter bases the loss estimate on the exposure, and ignores emerged losses. A hybrid is the Bornheutter–Ferguson method, which adds the emerged losses to an appropriate percentage of the exposure based estimate. This paper considers a weighting of these three estimators using credibility concepts. It generalizes the results of I. Robbin's paper, ‘A Bayesian Credibility Formula for IBNR Counts’ in PCAS 1986.

Analysis of Cobb angle measurements in scoliosis

The measurement of the magnitude of the deformity in idiopathic scoliosis is usually performed by either the Cobb method or the Ferguson method. In this study an error analysis of the Cobb method is given. The projection error is 3° and is more or less the same in moderate and severe scoliosis. The observation error is 3–5° in mild scoliosis and may increase to 10° or more in severe scoliosis. This observation error is strongly related to axial rotation of the vertebrae. Progression of the deformity in idiopathic scoliosis, either by increasing lateral deviation and/or increasing axial rotation is the indication to treatment. Because the Cobb angle is mainly influenced by the lateral deviation and less by the axial rotation, it is recommended to use, in addition to the Cobb method, an accurate method for measuring the axial rotation.

STATISTICAL ASSESSMENT OF TWO METHODS OF MEASURING SCOLIOSIS BEFORE TREATMENT

Regression analysis has shown that the Ferguson and Cobb methods of measuring spinal curvature give comparable results, at least before the scoliosis is treated. When the Cobb angle was calculated by multiplying the Ferguson angle by 1.38, the results were accurate to within 5 degrees in 28 (76%) of 37 cases. Any further debate over the merits of the two methods should focus on their inter- and intraobserver reproducibility and their applicability after corrective treatment.

Extension analysis of stretched belemnites: a comparison of methods

Stretched belemnites, and other fragmented rigid-brittle inclusions, offer great potential for estimating true extensions in deformed rocks. In the standard (Ramsay) method of analysis the elongation is calculated as 1 + e = L/L o where L is the final end-to-end length of the fragmented belemnite and L o is the original length (sum of the individual fragment lengths). This method always underestimates the true extension, usually by a substantial amount. An apparently trivial modification of the standard method, as used by Hossain, gives much improved extension estimates without any additional cost in time or effort. The strain-reversal method proposed by Ferguson is the most accurate method currently available but involves more laborious data collection, and subsequent computer processing. The three methods were applied to 120 stretched belemnites in the external French Alps. The different extension values calculated by the three methods arise because Ferguson's method is sensitive to the entire fracture-and-separation history, Hossain's method is sensitive to only part of that history, and Ramsay's method is history insensitive. If strain history is of prime interest Ferguson's method should be used, but the ease, speed, and relatively good performance of Hossain's method will make it attractive to many field geologists.

The level structure of 75Ge by the 74Ge(d, pγ) reaction

In order to investigate the level structure of 75Ge, pγ coincidence measurements of the 74Ge(d, pγ) 75Ge reaction were performed using a 6.0 MeV deuteron beam. (d, pγ) angular correlation measurements were also performed and analysed using the Litherland and Ferguson method II to yield spin assignments, mixing ratios and branching ratios of the γ-rays. A level scheme of 75Ge was built from energy and intensity relations of the protons and the γ-rays. The level scheme contained 42 levels and 104 γ-ray transitions. The spins were assigned or limited for 25 levels and mixing ratios were determined for 8 transitions. The level structure of 75Ge is discussed in comparison with odd nuclei around 75Ge.

A comparison of two parametric surface patch methods

The Bézier and Ferguson methods of representing surfaces are compared. Although there are very clear differences in their mode of use they are closely similar in their mathematical basis.

Un système de détection à 0° du faisceau, utilisant un triplet de lentilles quadrupolaires magnétiques

A new system in which charged particles are detected at 0° with respect to the incident beam has been designed. It used the focusing properties of three magnetic quadrupoles operating in the symmetric mode. The major advantage of this system is its large average solid angle of 12 × 10 −3 sr subtending an energy range of 20% of the mean value; it operates with a simple single circular counter of an area of 300 mm 2, and can be used for particle-gamma or particle-particle studies, according to the Litherland and Ferguson method.

Spins ofK42States by Gamma-Gamma Correlations

$\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ angular correlations were measured for $\ensuremath{\gamma}$ rays resulting from transitions in $^{42}\mathrm{K}$ which was formed by 6-MeV deuteron bombardment of separated $^{41}\mathrm{K}$. Litherland and Ferguson's Method I was used to study the cascade $\ensuremath{\gamma}$ rays from the 252- and 104-keV states. Acceptable spin sequences of 432 and 322, respectively, were found. Mixing ratios and population parameters are given.

Measurement of scoliosis.

Scoliosis measurement is a necessary part of the management. Radiologists should be aware of the two methods. The Ferguson method is best suited to curves under 50°. The Cobb method is best suited to curves of more than 50°.

A Comparative Study of the Two Popular Methods of Measuring Scoliotic Deformity of the Spine

The percentage of correction as determined by the Cobb method and the Ferguson method of measurement are not comparable. The differences and discrepancies between the two methods have been demonstrated and analyzed, showing the more favorable percentage of correction obtained by the Cobb method. When follow-up studies and end results are reported in the treatment of scoliosis, the method of measurement must be considered. Although both methods have their merits we have found the Ferguson method to be accurate. We believe it can be used by many orthopaedic surgeons with minimum, if any, error. Since this method depends on all the main components of the curve, it can be rightfully termed the method of the angle of the curve. A way of measuring the displacement of the apex of the curve toward the side of convexity of the curve has also been demonstrated as a simple and accurate way of following the progression or correction of a curve.

An Application of the Ferguson Method of Computing Item Conformity and Person Conformity

An Application of the Ferguson Method of Computing Item Conformity and Person Conformity