Anderson's Method Research Articles

An adaptive covariance relaxation method for ensemble data assimilation

For ensemble filters, accounting for unrepresented errors by inflating the ensemble perturbations can help improve filter performance. However, tuning the inflation factor can be costly, thus demanding adaptive covariance inflation (ACI) algorithms that give an online estimate of a temporally varying inflation factor. Additionally, a spatially varying inflation factor should be used to account for an irregular observation network. Anderson's adaptive inflation method offers a spatially and temporally varying inflation factor estimated from innovation statistics using a hierarchical Bayesian approach. In this study, we propose an alternative adaptive covariance relaxation (ACR) method that estimates a relaxation parameter online. Instead of treating inflation parameters as spatially varying random variables as in Anderson's method, the relaxation‐to‐prior‐spread method provides an ensemble spread reduction term that serves as a spatial mask to account for an irregular observation network. We demonstrate with a set of experiments using the 40‐variable Lorenz model that the ACR method is able to improve filter performance with the presence of sampling/model errors over a range of severity. Its reliability and ease of implementation suggest potential for future applications with atmospheric models.

RAD genotyping reveals fine-scale genetic structuring and provides powerful population assignment in a widely distributed marine species, the American lobster (Homarus americanus).

Deciphering genetic structure and inferring connectivity in marine species have been challenging due to weak genetic differentiation and limited resolution offered by traditional genotypic methods. The main goal of this study was to assess how a population genomics framework could help delineate the genetic structure of the American lobster (Homarus americanus) throughout much of the species' range and increase the assignment success of individuals to their location of origin. We genotyped 10156 filtered SNPs using RAD sequencing to delineate genetic structure and perform population assignment for 586 American lobsters collected in 17 locations distributed across a large portion of the species' natural distribution range. Our results revealed the existence of a hierarchical genetic structure, first separating lobsters from the northern and southern part of the range (FCT =0.0011; P-value=0.0002) and then revealing a total of 11 genetically distinguishable populations (mean FST =0.00185; CI: 0.0007-0.0021, P-value<0.0002), providing strong evidence for weak, albeit fine-scale population structuring within each region. A resampling procedure showed that assignment success was highest with a subset of 3000 SNPs having the highest FST . Applying Anderson's (Molecular Ecology Resources, 2010, 10, 701) method to avoid 'high-grading bias', 94.2% and 80.8% of individuals were correctly assigned to their region and location of origin, respectively. Lastly, we showed that assignment success was positively associated with sample size. These results demonstrate that using a large number of SNPs improves fine-scale population structure delineation and population assignment success in a context of weak genetic structure. We discuss the implications of these findings for the conservation and management of highly connected marine species, particularly regarding the geographic scale of demographic independence.

Note: Work function change measurement via improved Anderson method.

We propose the modification to the Anderson method of work function change (Δϕ) measurements. In this technique, the kinetic energy of the probing electrons is already low enough for non-destructive investigation of delicate molecular systems. However, in our implementation, all electrodes including filament of the electron gun are polarized positively. As a consequence, electron bombardment of any elements of experimental system is eliminated. Our modification improves cleanliness of the ultra-high vacuum system. As an illustration of the solution capabilities, we present Δϕ of the Ag(100) surface induced by cobalt phthalocyanine layers.

Modelling Lightning Strike on Overhead Lines for the Analysis of Back Flashover Using Electromagnetic Transient Program (EMTP)

This paper describes a lightning performance and provides an analytical tool to analyse the effect of lightning strikes of the overhead line construction. The analysis of lightning strike effect is performed through an Alternative Transient Program (ATP) package based on the Anderson method. The lightning strikes have significant impact on overhead lines because they are responsible for line outages due to back flashovers. While the back flashover can be determined based on a critical stroke current in each insulator string, the rate of line outages is difficult to be quantified in practice. This is because of the aspects involved, such as lightning surge mechanisms, geographical and environment factors, construction design of the overhead lines, stroke mechanism to the lines, and flashover mechanisms. This will then give some prior indication on how to improve overhead line lightning performance. It will also provide flexibility to conduct an investigation for other overhead line configuration.

English

The aim of this study is to assessor the tibial pilon fractures treated primarily with results of the articulated external fixation. The study included 24 patients (18 male, 6 female) with mean age of 26 &plusmn; 4.2 (range 18-51). According to the classification of AO/OTA, 6 cases were diagnosed as Type A, 4 cases as Type B and 14 cases as type C. Also, according to the Gustilo and Anderson method four of the cases were classified as grade I, two grade II and six grade III open fracture. For eight cases only the articulated external fixation was used, and for sixteen of the cases who have fibula injury at the syndesmosis level both articulated external fixation and plate-screw osteosynthesis for the restoration of the fibula was performed. While the articulated external fixation duration ranged from 8 to 14 weeks (10 &plusmn; 3.2 SD); follow up period was between 7 and 32 months (25 &plusmn; 4.6 SD). The results were evaluated according to the Teeny and Wiss criteria. The operation results of the patients were as follow: excellent for three, good for four, moderate for three, and poor for two of them. The complications encountered were bulla skin lesion for two of the cases at post-operative third day and non-union for one of the patients. There was no bone or soft tissue infection. The open tibial pilon fractures result from high-energy trauma; carry risk of serious injuries, loss of the range of the motion and infection can be safely treated with external fixation technique. &nbsp; Key words:&nbsp; External fixators, tibial fractures, intra-articular fractures.

An application of data envelopment analysis for measuring the relative efficiency in banking industry

Article history: Received 5 January 2014 Received in revised format 8 March 2014 Accepted 11 March 2014 Available online 12 March 2014 Measuring the relative efficiency of banking industry has been a popular subject among both practitioners and academicians. Data envelopment analysis (DEA) has been widely applied for different purposes. This paper presents an empirical investigation to measure the relative efficiency of various banks located in province of Semnan, Iran. The proposed study uses DEA method to rank all units and using Anderson and Peterson method (1993) [Andersen, P., & Petersen, N. C. (1993). A procedure for ranking efficient units in data envelopment analysis. Management Science, 39, 1261-1264], we provide some super efficiency for inefficient units. The study also provides reference numbers for inefficient units and gives some target values for all inefficient units. © 2014 Growing Science Ltd. All rights reserved.

Dose calculation accuracy at presence of dental implants on UNCORRECTED and metal artifact reduced computed tomography data

Dose calculation accuracy at presence of dental implants on UNCORRECTED and metal artifact reduced computed tomography data

Metabolic Syndrome Performs Better Than the Individual Factors in Predicting Renal Graft Outcome

Individual components of the metabolic syndrome (MS), especially obesity and hypertension, have a deleterious effect on renal graft outcome. Whether MS is better than its individual components in predicting the decline of renal function is unknown. We studied the presence of MS and its individual components at 12 months post-transplantation according to the Adult Treatment Panel III classification and their influence on measured graft function. A cohort of 322 patients who underwent transplantation between 1996 and 2003 and who agreed to have their glomerular filtration rate (GFR) measured by urinary clearance of technetium 99m (Tc*-DTPA) (measured GFR [mGFR]) at 3, 12, 48, 60, and 96 months after transplantation were included. The patients were followed up until patient death, graft loss, or December 2009 (mean follow-up: 3 ± 2.8 years). The linear mixed effect model for longitudinal repeated measures was applied. To compare MS versus its components we used the Akaike information Criterion (AIC) to determine the best model according to the Anderson and Burnham method. Univariate and multivariate analyses models using MS were more efficient than those using the individual components, which consisted of waist circumference, low high-density lipoprotein-cholesterol, hypertriglyceridemia, hyperglycemia, and systolic and diastolic blood pressure. The AIC was the lowest with MS models indicating better prediction on graft function than the individual components. MS is a better predictor of mGFR decline than its individual components. It is a valid and precious tool to assess outcomes.

Modified Anderson Method for Accelerating 3D-RISM Calculations Using Graphics Processing Unit.

A fast algorithm is proposed to solve the three-dimensional reference interaction site model (3D-RISM) theory on a graphics processing unit (GPU). 3D-RISM theory is a powerful tool for investigating biomolecular processes in solution; however, such calculations are often both memory-intensive and time-consuming. We sought to accelerate these calculations using GPUs, but to work around the problem of limited memory size in GPUs, we modified the less memory-intensive "Anderson method" to give faster convergence to 3D-RISM calculations. Using this method on a Tesla C2070 GPU, we reduced the total computational time by a factor of 8, 1.4 times by the modified Andersen method and 5.7 times by GPU, compared to calculations on an Intel Xeon machine (eight cores, 3.33 GHz) with the conventional method.

Do Patients with Glaucoma Have Difficulty Recognizing Faces?

To compare face recognition performance of glaucomatous patients with age-similar visually healthy people. Percentage of correctly identified faces in the Cambridge Face Memory Test was assessed in glaucomatous patients (n = 54; mean age = 69) with a range of visual field (VF) defects and visually healthy controls (n = 41; mean age = 67). All participants underwent cognitive and visual assessment (binocular visual acuity [BVA], contrast sensitivity [CS], and Humphrey VFs, both 10-2 and 24-2) and had BVA of at least 0.18 logMAR. Patients were classified as having "early," "moderate," or "advanced" VF defects using the Hodapp, Parrish and Anderson Method: Patients were also stratified by better-eye 10-2 mean deviation (MD) being better or worse than the 1% normative value. There were no significant differences in age (P = 0.25) or cognitive ability (P = 0.31) between groups; however, differences in BVA and CS were statistically significant (P < 0.05). Patients with advanced VF defects identified fewer faces on average (±SD) (66% ± 15%) than those with early (75% ± 11%) and moderate (75% ± 13%) defects and controls (75% ± 11%); P < 0.05. Patients with a best-eye 10-2 MD P < 1% identified fewer faces (67% ± 13%) than those with 10-2 MD P > 1% (77% ± 11%) and controls P < 0.01 (75% ± 11%). Multiple regression analysis revealed CS was important for face recognition. When compared with age-similar people with healthy vision, glaucomatous patients with advanced bilateral 24-2 VF loss, significant 10-2 VF loss, or poor CS are more likely to experience problems with face recognition.

Aligning a reflection cavity by Anderson’s method

The sounding rocket principle of equivalence measurement uses a set of four laser gauges operating in Fabry-Perot cavities to determine the relative acceleration of two test masses that are chemically different. One end of each cavity is a flat mirror on a test mass. Because the test masses are unconstrained and thus expected to rotate slightly during measurement, and because the distance measurements are made at the sub-picometer level, it is essential to have real-time alignment of the beam entering the cavity. However, the cavity must be used in reflection and space is limited. We show that Anderson's alignment method can be used in reflection, but that it requires that the Fabry-Perot cavity have mirrors with significantly unequal reflectivities.

Effect of temperature and solvents on ultrasonic velocity and thermodynamic parameters of 1,3,4-oxadiazole derivative solutions

Abstract The present work describes the synthesis, characterization, thermal analysis and physico-chemical parameters of 2-((4-acetyl-5-methyl-5-phenyl-4,5-dihydro-1,3,4-oxadiazol-2-yl)methylthio)-3-o-tolylquinazolin-4( 3H )-one (PD I-H ). The compound PD I-H is synthesized by using standard protocols; purity is monitored by using TLC and characterized by IR and NMR spectral techniques. The thermal behavior of PD I-H was studied by TGA and DTA techniques at a heating rate of 10 °C/min in nitrogen atmosphere. Thermal stability and kinetic parameters were determined according to the Freeman–Anderson method. The density ( ρ ), viscosity ( η ) and ultrasonic velocity ( U ) of pure solvents (chloroform (CF), N,N -dimethyl formamide (DMF)) and solutions of PD I-H (0.01 – 0.001 M) in CF and DMF were investigated at three different temperatures: 303 K, 308 K and 313 K. Using ρ , η and U data various thermodynamic parameters such as adiabatic compressibility ( κ a ), intermolecular free path length ( L f ), Rao's molar sound function ( R m ), Van der Waals constant ( b ), internal pressure ( π ), free volume ( V f ) and solvation number ( S n ) were calculated. The results obtained were interpreted in terms of solute–solvent and solute–solute interactions. The structure making or structure-breaking abilities of the solute in CF and DMF solvent were also studied.

SIFs of CCT plate repaired with single‐sided composite patch

ABSTRACTConstant amplitude load fatigue tests are performed to obtain crack propagation data for LF2‐aluminium centre crack tension (CCT) plates un‐repaired and repaired with single‐sided composite patches. Then, the James–Anderson method, an experimental method, is used to obtain the stress intensity factor (SIF) formula for the repaired CCT plates with carbon–fibre composite patches. At last, crack propagation life prediction and finite element (FE) calculation are carried out to validate the experimental SIF formula. It is shown that the present SIF formula can exactly predict the fatigue‐crack propagation life of the patched CCT plates and is close to the FE results, which implies the effectivity of the experimental SIF formula in the present paper.

Strain rates in northwestern Italy from spatially smoothed seismicity

This work presents seismic strain rate maps for the Western Alps and Northern Apennines (northern Italy) as derived from an earthquake catalog collecting both historical and instrumental data. Strain rates are calculated on the basis of the rate of seismic moment release using the Anderson method. Unlike previous applications, which determined the total strain rate associated with specific seismogenic sources, we have employed an innovative zoneless approach based on a spatially smoothed seismicity method. In addition, a Monte Carlo simulation procedure is applied to allow for uncertainty in the input data (e.g., magnitude to moment conversion, seismogenic thickness, maximum earthquake magnitude). Strain rate maps are developed by summing the moments of the earthquakes reported in the catalog and by using two different earthquake recurrence relations. Our results indicate that deformation rates are quite high, ranging from about 2 to 12 × 10−9 yr−1 in the Northern Apennines and from 0.5 to 6 × 10−9 yr−1 in the Western Alps. These values, however, are ∼1 order less than those derived from Global Positioning System measurements, suggesting that a portion of the recent deformation in northwestern Italy is related to aseismic processes. The discrepancies between seismic and geodetic strain rates may also indicate that the record of seismicity may not provide a sufficient time window for assessment of secular rates of moment release (or secular deformation rates) and rates of recurrence of large magnitude earthquakes in the study area.

Reformulation of the Anderson method using singular value decomposition for stable convergence in self-consistent calculations

Reformulation of the Anderson method using singular value decomposition for stable convergence in self-consistent calculations

Acceleration of Fast Multipole Method Using Special-Purpose Computer Grape

We have implemented the fast multipole method (FMM) on a special-purpose computer GRAPE (GRAvity piPE). The FMM is one of the fastest approximate algorithms to calculate forces among particles. Its calculation cost scales as O( N), while the naive algorithm scales as O( N2). Here, N is the number of particles in the system. GRAPE is hardware dedicated to the calculation of Coulombic or gravitational forces among particles. GRAPE's calculation speed is 100—1000 times faster than that of conventional computers of the same price, though it cannot handle anything but force calculation. We can expect significant speedup by the combination of the fast algorithm and the fast hardware. However, a straightforward implementation of the algorithm actually runs on GRAPE at rather modest speed. This is because of the limited functionality of the hardware. Since GRAPE can handle particle forces only, just a small fraction of the overall calculation procedure can be put on it. The remaining part must be performed on a conventional computer connected to GRAPE. In order to take full advantage of the dedicated hardware, we modified the FMM using the pseudoparticle multipole method and Anderson's method. In the modified algorithm, multipole and local expansions are expressed by distribution of a small number of imaginary particles (pseudoparticles), and thus they can be evaluated by GRAPE. Results of numerical experiments on ordinary GRAPE systems show that, for large- N systems ( N ≥ 105), GRAPE accelerates the FMM by a factor ranging from 3 for low accuracy (RMS relative force error ~10—2) to 60 for high accuracy (RMS relative force error ~10— 5). Performance of the FMM on GRAPE exceeds that of Barnes—Hut treecode on GRAPE at high accuracy, in case of close-to-uniform distribution of particles. However, in the same experimental environment the treecode outperforms the FMM for inhomogeneous distribution of particles.

Basic exchange model: Comparison of Anderson and valence bond configuration interaction approaches and an alternative exchange expression

The application of the Anderson [Phys. Rev. 115, 2 (1959)] and valence bond configuration interaction (VBCI) methods on a basic exchange model is investigated to assess their ability to calculate the exchange energy under a variety of physical situations, represented by the model parameters. The model comprises two metal orbitals and a central ligand orbital. We show that the validity of the Anderson method is not restricted to cases in which $U⪡\ensuremath{\Delta}$ if the ``repulsion assisted transfer'' term is included in the exchange expressions. We discuss the influence of the Coulomb repulsion in the metal and ligand orbitals on the Anderson method, pointing out some deficiencies of the Anderson orbitals. In cases of strong metal-ligand covalency, the VBCI method fails due to its perturbational character. The modified Anderson exchange performs better in some of these cases, depending on the specific situation. Based on the concept of a strict separation of covalent and exchange effects, we derive an exchange expression that overcomes all the discussed difficulties of the Anderson and VBCI methods.

Development of parallel density functional program using distributed matrix to calculate all‐electron canonical wavefunction of large molecules

We developed a new parallel density-functional canonical molecular-orbital program for large molecules based on the resolution of the identity method. In this study, all huge matrices were decomposed and saved to the distributed local memory. The routines of the analytical molecular integrals and numerical integrals of the exchange-correlation terms were parallelized using the single program multiple data method. A conventional linear algebra matrix library, ScaLAPACK, was used for matrix operations, such as diagonalization, multiplication, and inversion. Anderson's mixing method was adopted to accelerate the self-consistent field (SCF) convergence. Using this program, we calculated the canonical wavefunctions of a 306-residue protein, insulin hexamer (26,790 orbitals), and a 133-residue protein, interleukin (11,909 orbitals) by the direct-SCF method. In regard to insulin hexamer, the total parallelization efficiency of the first SCF iteration was estimated to be 82% using 64 Itanium 2 processors connected at 3.2 GB/s (SGI Altix3700), and the calculation successfully converged at the 17-th SCF iteration. By adopting the update method, the computational time of the first and the final SCF loops was 229 min and 156 min, respectively. The whole computational time including the calculation before the SCF loop was 2 days and 17 h. This study put the calculations of the canonical wavefunction of 30,000 orbitals to practical use.

The Double Exchange Phenomenon Revisited: The [Re2OCl10]3− Compound

Correlated ab initio calculations have been performed on the [Re2OCl10]3− anion. The calculated spectrum does not respect the intervals given by the usually accepted double exchange Hamiltonian. Surprisingly enough the ground-state happens to be of intermediate spin multiplicity (i.e. a quartet) at any level of correlation treatment. A model that combines the Anderson and Hasegawa method and the usually used double exchange one rationalizes the spectrum calculated both by a configuration interaction restricted to the open shell molecular orbitals and at a more correlated level of calculation. An alternative analysis of the double exchange phenomenon, based on a molecular orbital language, is presented. The specific effects of the electronic correlation brought by extended active space and by a difference dedicated configuration interaction are also analyzed.

Progression of visual field loss in open angle glaucoma in the Melbourne Visual Impairment Project

To quantify the progression of visual field loss in participants with open angle glaucoma. Cluster random samples of 3271 participants participated in this study. Each participant underwent a standardized ophthalmic examination, which included intraocular pressure measurement, Humphrey 24-2 Fastpac visual field testing and stereophotography of the optic disc. At baseline 118 participants were identified as possible, probable or definite open angle glaucoma and 74 (62.7%) of these were seen again at the follow-up examination. Progression of visual field loss was defined using three methods: the Advanced Glaucoma Intervention Study criteria, the modified Anderson criteria and the Blumenthal method. In total, 49% of subjects showed progressive visual field loss with at least one method. The Blumenthal criteria yielded the highest rate of progression (37%), followed by the modified Anderson method (33%) and the Advanced Glaucoma Intervention Study method (16%). The progressive visual field loss was associated with baseline glaucoma status (P = 0.02); 65% of the definite glaucoma progressed, compared with 57% of the probable glaucoma and 25% of the possible glaucoma. Participants who had been previously diagnosed with glaucoma had a higher rate of progression (54%) when compared with those who had not been diagnosed previously (47%). In total, 50% (four of eight) of those receiving glaucoma medication at baseline had progressive visual field loss; all were in the definite glaucoma category. Despite use of glaucoma medications the majority of glaucoma patients managed by their regular ophthalmologist experienced progressive visual field loss over a 5-year period.