Estimation Of Different Types Research Articles

Denosumab for the Prevention of Osteoporotic Fractures in Post-Menopausal Women

The National Institute for Health and Clinical Excellence (NICE) invited the manufacturer of denosumab (Amgen Inc., UK) to submit evidence for the clinical and cost effectiveness of denosumab for the prevention of fragility fractures in post-menopausal women, as part of the Institute's single technology appraisal (STA) process. The University of Aberdeen Health Technology Assessment Group were commissioned to act as the Evidence Review Group (ERG); the role of the ERG being to appraise the manufacturer's submission and to produce an independent report. This article provides a description of the company submission, the ERG review and NICE's subsequent decisions. The manufacturer considered that denosumab would be appropriate for patients unable to take, comply with or tolerate oral bisphosphonates. Comparator treatments selected for the submission were, therefore, 'no treatment', raloxifene, strontium ranelate, intravenous zoledronic acid, intravenous ibandronate and teriparatide. The main effectiveness evidence for denosumab was derived from a large randomized controlled trial comparing denosumab with placebo. Given by subcutaneous injection at 6-monthly intervals for 3 years, denosumab reduced the incidence of hip fracture by 40%, and reduced the incidence of clinical vertebral fracture by 69%. An indirect treatment comparison was used to derive adjusted relative risk (RR) estimates for different types of fracture for each comparator versus placebo. The RRs (95% CI) applied for denosumab were 0.316 (0.208, 0.478) for clinical vertebral fracture, 0.605 (0.373, 0.983) for hip fracture and 0.842 (0.638, 1.110) for wrist fracture. Despite a number of concerns surrounding the methodology of the indirect comparison, the ERG was satisfied with the robustness of the effect estimates. The RR estimates were applied in a good-quality Markov model that took account of drug costs, administration and monitoring costs, costs associated with fractures, and long-term nursing home costs. Utility weights were used to adjust time spent in fracture states, allowing QALYs to be estimated. The base-case analysis was conducted for women aged 70 years with a T-score of -2.5 or less and no prior fracture, and women aged 70 years with a T-score of -2.5 or less with a prior fragility fracture. Subgroup analyses based on T-score and independent clinical risk factors were also undertaken. Applying a willingness-to-pay (WTP) threshold of £30 000 per QALY, the manufacturer's results suggested that denosumab would offer a cost-effective alternative to all treatment comparators for the primary and secondary prevention of fractures. The ERG was concerned about an assumption that denosumab would be administered in general practice at the average cost of two standard GP visits a year. As a result, the ERG requested some further sensitivity analysis and undertook some further modelling, applying an assumption that denosumab would be provided primarily in secondary care. This modification altered the cost effectiveness of denosumab versus 'no treatment' (in women with no prior fragility fracture) and zoledronic acid. The NICE Appraisal Committee concluded that, as a treatment option for the prevention of osteoporotic fractures, denosumab should be recommended only in post-menopausal women at increased risk of fracture who cannot comply with the special instructions for administering oral bisphosphonates, or have an intolerance of, or contraindication to, those treatments. For primary prevention, the Appraisal Committee also stipulated specific levels of fracture risk at which denosumab is recommended.

Does interview setting influence disclosure of violence? A study in elderly

Violence is a very sensitive research topic and interview's setting might influence the participation rate and response accuracy. We aimed to evaluate such effect when assessing the prevalence of different types of violence in a sample of urban elderly by comparing those interviewed at home with those assessed at the research office. Study subjects were members of a cohort of urban dwellers previously assembled using random digit dialling. The initial 450 individuals aged 60-84 years old were invited to participate in the present study, after being randomly allocated into two groups: 150 for being scheduled to research office interview and 300 to home interview. Both groups allocated were similar regarding gender, age, education, marital status and behavioural characteristics such as smoking and drinking alcohol. Information was obtained by face-to-face standardised interviews. We obtained a participation rate of 67.0% in the group allocated to home interview and 70.7% in the other group (P = 0.431). No statistically significant differences were found when prevalence of violence during the previous year was compared according to the interview setting (physical 2.5 versus 1.0%, psychological 19.7 versus 19.0%, financial mistreatment 8.6 versus 9.5%, sexual 1.0 versus 1.0% and neglect 5.1 versus 3.8% in home and research office, respectively). Our results indicate that the interview setting has no influence both in participation rate and in the prevalence estimates of different types of violence in the elderly.

Lake Ladoga ice phenology: Mean condition and extremes during the last 65 years

AbstractWinter conditions play an important role for the largest lake in Europe—Lake Ladoga. The ice cover lasts for 171 ± 3 days on average from the early November until the mid‐May. We investigated the ice regime of Lake Ladoga using a constructed ice database of aircraft surveys and satellite images. More than 1250 surveys of the lake's ice cover from 1943 to 2010 were collected and analysed to determine mean and extreme ice conditions for winters of different types of severity. The time series of ice cover percentage over the lake was plotted. On average, 18 observational ice charts were made every winter. Individual ice phenology records show considerable year‐to‐year variation. For this reason, records typically have been combined and analysed as groups (categories). Extremely cold winters were determined as winters with complete ice cover that lasts more than three months which is approximately 90% quartiles from all winters with complete ice cover. The lake surface was completely covered with ice for more than three months during 5 seasons. Extremely warm winters when the maximum ice cover was less than 70% of the lake area occurred during 5 seasons as well. A basic relationship between the winter severity as winter maximum of accumulated freezing degree‐days (AFDD) and the earlier derived Relative Ice Cover Index (RICI) was established. We have used teleconnection indices such as North Atlantic Oscillations (NAO) and Arctic Oscillation (AO) for the period from October to May for estimation of different types of Lake Ladoga's ice conditions. The AO index in winter months and local winter maximum of AFDD explained much of the interannual variation in ice cover. Copyright © 2011 John Wiley & Sons, Ltd.

Approximation properties of fuzzy transforms

We enlarge the class of fuzzy transforms (F-transforms) by considering different types of fuzzy partitions. New types of F-transforms are constructed based on B-splines, Shepard kernels, Bernstein basis polynomials and Favard–Szász–Mirakjan type operators. We study approximation properties of F-transforms. Particular cases of the classical Korovkin's theorems are presented, together with new error estimates for different types of fuzzy transforms. It turns out that F-transforms can be studied in the framework of classical approximation theory.

The mstate package for estimation and prediction in non- and semi-parametric multi-state and competing risks models

In recent years, multi-state models have been studied widely in survival analysis. Despite their clear advantages, their use in biomedical and other applications has been rather limited so far. An important reason for this is the lack of flexible and user-friendly software for multi-state models. This paper introduces a package in R, called ‘ mstate’, for each of the steps of the analysis of multi-state models. It can be applied to non- and semi-parametric models. The package contains functions to facilitate data preparation and flexible estimation of different types of covariate effects in the context of Cox regression models, functions to estimate patient-specific transition intensities, dynamic prediction probabilities and their associated standard errors (both Greenwood and Aalen-type). Competing risks models can also be analyzed by means of mstate, as they are a special type of multi-state models. The package is available from the R homepage http://cran.r-project.org. We give a self-contained account of the underlying mathematical theory, including a new asymptotic result for the cumulative hazard function and new recursive formulas for the calculation of the estimated standard errors of the estimated transition probabilities, and we illustrate the use of the key functions of the mstate package by the analysis of a reversible multi-state model describing survival of liver cirrhosis patients.

Hybrid evolutionary algorithm for microscrew thread parameter estimation

In this paper we propose a novel approach to the problem of microscrew thread parameter estimation based on a hybrid evolutionary algorithm that combines a stochastic evolutionary algorithm with the deterministic inverse parabolic interpolation. The proposed method uses a machine vision system utilizing a single web camera. The hybrid evolutionary algorithm was tested on a specially created image database of microscrews. Experimental results prove speed and efficiency of the proposed method and its robustness to noise in the images. This method may be used in automated systems of real-time non-destructive quality control of microscrews and has potential for parameter estimation of different types of microparts.

COPD and chronic bronchitis risk of indoor air pollution from solid fuel: a systematic review and meta-analysis

BackgroundOver half the world is exposed daily to the smoke from combustion of solid fuels. Chronic obstructive pulmonary disease (COPD) is one of the main contributors to the global burden...

Frequency-Band Coupling in Surface EEG Reflects Spiking Activity in Monkey Visual Cortex

Although the electroencephalogram (EEG) is widely used in research and clinical settings, its link to the underlying neural activity during sensory processing remains poorly understood. To investigate this, we made simultaneous recordings of surface EEG, intracortical local field potential, and multiunit activity (MUA) in the alert monkey visual cortex during presentation of natural movies. Using a general linear model, we show that in single trials, EEG power in the gamma band (30-100 Hz) and phase in delta band (2-4 Hz) are significant predictors of the MUA response. Specifically, we found that the MUA response was strongest only when increases in EEG gamma power occurred during the negative-going phase of the delta wave, thus revealing a frequency-band coupling mechanism that can be exploited to infer population spiking activity. This finding may open up a new dimension in the use and interpretation of EEG in normal and pathological conditions.

Modified intra-cerebral challenge assay for acellular pertussis vaccines: Comparisons among whole cell and acellular vaccines

The modified intra-cerebral challenge assay for acellular pertussis vaccines is used in Japan, Korea, China and possibly other Asian countries as the potency assay for routine release of acellular pertussis (aP) and combination vaccines. National reference standards, typically of whole cell pertussis (Pw) vaccine, are in use in these countries, but there is no agreed international reference standard for acellular pertussis vaccines.We report here the results of a collaborative study initiated in September 2006 in which fourteen laboratories performing the modified intra-cerebral challenge assay took part. These laboratories compared their various national references of Pw vaccine, the third International Standard for whole cell pertussis vaccine, a previously studied two-component freeze-dried aP vaccine preparation coded JNIH-3, and four different aP vaccines in combination with diphtheria and tetanus toxoids.The results of this study show that the modified intra-cerebral challenge assay works reliably although there are inter-laboratory variations in potency estimates. Pw and aP vaccines show apparent differences in dose–response lines in some assay systems. This indicates dissimilarity in performance in at least some of these assay systems. Estimates of relative potency for aP vaccines in terms of the Pw vaccine national or in-house reference preparations differ significantly from one another. Different mouse strains were used in each country and the different strains may also differ in their responsiveness to Pw and aP vaccines. Estimates for different types of aP vaccine formulations show less inter-laboratory variation in terms of JNIH-3 than in terms of the third IS for Pw vaccine and the remaining variation is not apparently related to the different mouse strains. This study thus suggests that an aP vaccine standard would improve inter-laboratory agreement. These data do not show significant dissimilarity in dose–response lines between JNIH-3 and the various vaccine products included, irrespective of the differences in aP components. Available data indicate that JNIH-3 is sufficiently stable to serve as an International Standard. On the basis of these results and with the agreement of the participants, it was proposed that JNIH-3 should be established as an International Standard for acellular pertussis vaccine for use in the modified intra-cerebral challenge assay and other protective bioassays, with an assigned activity of 34 International Units (IU) per ampoule.A WHO Working Group on Standardization of Acellular Pertussis Vaccines: potency assay met in Beijing, China, 7–9 November 2007. This group considered the report of this study, the comments of the participants and implications of the use of JNIH-3 as a reference standard and recommended establishment of JNIH-3 as an International Standard. The results of this study and the report of the Working Group were submitted to the Expert Committee on Biological Standardization (ECBS) of WHO which established JNIH-3 as the first International Standard for acellular pertussis vaccine in the modified intra-cerebral challenge assay and other protective bioassays with an assignment of 34IU per ampoule in October 2008.

On the assessment of modal nonlinear pushover analysis for steel frames with semi-rigid connections

Applying nonlinear statistical analysis methods in estimating the performance of structures in earthquakes is strongly considered these days. This is due to the methods' simplicity, timely lower cost and reliable estimation in seismic responses in comparison with time-history nonlinear dynamic analysis. Among nonlinear methods, simplified to be incorporated in the future guidelines, Modal Pushover Analysis, known by the abbreviated name of MPA, simply models nonlinear behavior of structures; and presents a very proper estimation of nonlinear dynamic analysis using lateral load pattern appropriate to the mass. Mostly, two kinds of connecting joints, 'hinge' and 'rigid', are carried out in different type of steel structures. However, it should be highly considered that nominal hinge joints usually experience some percentages of fixity and nominal rigid connections do not employ totally rigid. Therefore, concerning the importance of these structures and the significant flexibility effect of connections on force distribution and elements deformation, these connections can be considered as semi-rigid with various percentages of fixity. Since it seems, the application and implementation of MPA method has not been studied on moment-resistant steel frames with semi rigid connections, this research focuses on this topic and issue. In this regard several rigid and semi-rigid steel bending frames with different percentages of fixity are selected. The structural design is performed based on weak beam and strong column. Followed by that, the MPA method is used as an approximated method and Nonlinear Response History Analysis (NL-RHA) as the exact one. Studying the performance of semi-rigid frames in height shows that MPA technique offers reasonably reliable results in these frames. The methods accuracy seems to decrease, when the number of stories increases and does decrease in correlation with the semi-rigidity percentages. This generally implies that the method can be used as a proper device in seismic estimation of different types of low and mid-rise buildings with semi-rigid connections.

Measuring effect sizes using manifest versus latent variables: consequences and implications for research

Reporting of effect sizes allows the description of mean differences independently of sample size. In current research, these statistical values are usually calculated at the manifest level. Calculating effect sizes at the latent level within a structural equation model can, however, result in more valid, different and potentially higher estimates. Therefore, the manifest and latent estimation of different types of effect sizes in a large rehabilitation research data set were compared. The impact of the different methods for estimating effect sizes in subgroups generated by indication, sex and age was demonstrated. Calculations were conducted using data from a meta-analysis (N=5809) in which the subjective health status of patients in orthopedic (N=2386), cardiological (N=1976) and psychosomatic rehabilitation (N=1447) was measured. The results were standardized effect sizes between 0.03 and 1.44 and standardized response means between 0.05 and 1.31 for manifest variables and standardized effect sizes between 0.04 and 1.58 and standardized response means between 0.07 and 1.45 for latent variables. Thus, latent effect sizes were generally higher, although no specific factor for transforming manifest into latent effect sizes seems to exist. Although the computation of latent effect sizes does not necessarily yield higher estimates, it should nonetheless be carried out as a matter of routine.

Optimal filtration of a signal against flicker noises

The problem of optimal filtering the signal frequency at the frequency detector output against flicker noises with the power spectral density ω−γ is considered. In a stationary approximation, a simple fractionally rational model of the spectra of frequency finite-power flicker noises is proposed. The optimal impulse response function of the device, which ensures an effective, unbiased, and consistent estimate of the parameter with regard to the edge effects at the ends of the measurement interval and the optimal frequency estimate variance are obtained. Precision of the estimates for different types of noise and device is compared.

A Family of Estimators of Finite-Population Distribution Function Using Auxiliary Information

This paper considers the problem of estimating the finite-population distribution function and quantiles with the use of auxiliary information at the estimation stage of a survey. We propose the families of estimators of the distribution function of the study variate y using the knowledge of the distribution function of the auxiliary variate x. In addition to ratio, product and difference type estimators, many other estimators are identified as members of the proposed families. For these families the approximate variances are derived, and in addition, the optimum estimator is identified along with its approximate variance. Estimators based on the estimated optimum values of the unknown parameters used to minimize the variance are also given with their properties. Further, the family of estimators of a finite-population distribution function using two-phase sampling is given, and its properties are investigated.

Advanced aspects of electromagnetic SERS enhancement factors at a hot spot

AbstractIn this paper, we discuss some advanced theoretical aspects of electromagnetic enhancement factors (EFs) in surface‐enhanced Raman scattering (SERS). We focus in particular on the influence of surface selection rules (SSRs) on SERS EFs at hot spots, and the determination of SERS depolarization ratios. Both aspects could be viewed as secondary (compared to the overall magnitude of the SERS EF), but are nevertheless observable experimentally and crucial for a fundamental understanding of SERS. They also share the property that they cannot be studied within the commonly used |E | 4 approximation to the SERS EFs, and appropriate tools are developed here to make predictions beyond this approximation in the case of a SERS hot spot. In addition, theoretical estimates of different types of (previously defined) EFs are provided, and their origins discussed for the typical example of a SERS substrate dominated by SERS hot spots. Finally, experimental measurements of SERS depolarization ratios are presented to support the theoretical predictions. Copyright © 2008 John Wiley & Sons, Ltd.

Prevalence of anaemia before major joint arthroplasty and the potential impact of preoperative investigation and correction on perioperative blood transfusions

Preoperative investigation and treatment of anaemia is recommended before orthopaedic surgery. We measured the prevalence of anaemia among admissions presenting for elective major joint arthroplasty (MJA), assessed their transfusion requirements, and investigated factors associated with perioperative blood transfusion. All admissions to a dedicated elective orthopaedic hospital during 2000-2001 were studied. The patients' database was merged with the haematology and transfusion databases. Population estimates for different types of anaemia and their blood transfusion requirements were generated using local reference ranges (males <130 g litre(-1); females <115 g litre(-1)). One thousand three hundred and twenty-two admissions were included; haematology data were complete for 1142 (544 primary hip, 490 primary knee, 77 revision hip, 31 revision knee). About 19.6% were anaemic [7.1% haemoglobin (Hb) <110 g litre(-1); 1.6% Hb<100 g litre(-1)]. Overall, 21.3% of admissions were transfused (mean 0.58 units per case: 95% CI 0.50-0.61). For anaemic admissions, 42.0% were transfused (mean 1.11 units per case: 95% CI 0.90-1.32). Mean red cell use for admissions with normocytic normochromic anaemia (12.7% of admissions) and hypochromic anaemia (4.6%) was 1.04 (95% CI 0.78-1.31) and 1.14 (95% CI 0.71-1.57) units per admission, respectively. Factors strongly associated independently with transfusion were preoperative haemoglobin </=110 g litre(-1) [odds ratio: 13.92 (95% CI 7.77-24.9) and revision hip surgery (OR: 17.80 (9.59-33.02)]. The prevalence of preoperative anaemia among admissions undergoing elective MJA is approximately 20%. Patients most likely to avoid transfusions with preoperative intervention are those with low haemoglobin undergoing revision hip surgery.

Bias in Variance Components Due to Nonresponse in Twin Studies

Incomplete data on trait values may bias estimates of genetic and environmental variance components obtained from twin analyses. If the nonresponse mechanism is 'ignorable' then methods such as full information maximum likelihood estimation will produce consistent variance component estimates. If, however, nonresponse is 'nonignorable', then the situation is more complicated. We demonstrate that a within-pair correlation of nonresponse, possibly different for monozygotic (MZ) and dizygotic (DZ) twins, may well be compatible with 'ignorability'. By means of Monte Carlo simulation, we assess the potential bias in variance component estimates for different types of nonresponse mechanisms. The simulation results guide the interpretation of analyses of data on perceptual speed from the Swedish Adoption/Twin Study of Aging. The results suggest that the dramatic decrease in genetic influences on perceptual speed observed after 13 years of follow-up is not attributable solely to dropout from the study, and thus support the hypothesis that genetic influences on some cognitive abilities decrease with age in late life.

Bias in Variance Components Due to Nonresponse in Twin Studies

AbstractIncomplete data on trait values may bias estimates of genetic and environmental variance components obtained from twin analyses. If the nonresponse mechanism is ‘ignorable’ then methods such as full information maximum likelihood estimation will produce consistent variance component estimates. If, however, nonresponse is ‘nonignorable’, then the situation is more complicated. We demonstrate that a within-pair correlation of nonresponse, possibly different for monozygotic (MZ) and dizygotic (DZ) twins, may well be compatible with ‘ignorability’. By means of Monte Carlo simulation, we assess the potential bias in variance component estimates for different types of nonresponse mechanisms. The simulation results guide the interpretation of analyses of data on perceptual speed from the Swedish Adoption/Twin Study of Aging. The results suggest that the dramatic decrease in genetic influences on perceptual speed observed after 13 years of follow-up is not attributable solely to dropout from the study, and thus support the hypothesis that genetic influences on some cognitive abilities decrease with age in late life.

Injuries in Aleppo, Syria; first population-based estimates and characterization of predominant types

BackgroundDespite the growing burden of injuries worldwide, Syria and many other Arab countries still lack population-based estimates of different types of injuries. This study aims toprovide first population-based estimates of major injuries in Syria and characterize groups at increased risk.MethodsAn interviewer-administered population-based survey of adults 18–65 years residing in Aleppo, Syria was conducted in 2004. The study sample involved 2038 household representatives in Aleppo (45.2% men, mean age 35.3 ± 12.1, response rate 86%). We inquired about participants self-reported injuries in the past year that required medical attention as well as injuries among their household members. When reported, injuries were further assessed according to type, place, and outcome.ResultsOverall, there was 153 self-reported injuries in the past year (77.3 per 1000 adult respondents, 93.1 per 1000 in men and 64.4 per 1000 in women, p = 0.02). Other than gender, injuries differed by age (the older age group being least affected), and place of occurrence, as men were more likely to sustain traffic injuries and be injured outside the home. Injuries were reported among 236 household members (21.0 per 1000), and were slightly more frequent in children than adults (22.0 per 1000 for children, and 19.7 per 1000 for adults, p = 0.2). Traffic injuries, falls, and poisoning (food) were by far the most common types of injury experienced by participants as well as their household members. Falls and traffic injuries seem to have caused most morbidity for the injured, while burns, although not frequently reported, were associated with an unfavorable outcome in the majority of cases.ConclusionThis information provides baseline information about the burden of different injuries in Syria, and the sociodemographic factors related to them.

Using multiparametric auxiliary information at the estimation stage

Difference type estimators use auxiliary information based on an auxiliary parameter (specifically the parameter of interest), associated with the auxiliary variable. In practice, however, several parameters for auxiliary variables are available. This paper discusses how such estimators can be modified to improve the usual methods if information related to other parameters associated with an auxiliary variable or variables is available. Some applications estimating several such parameters are described. A proper set of simulation-based comparisons is made.

Estimating individual tree heights of sugi (Cryptomeria japonica D. Don) plantations in mountainous areas using small-footprint airborne LiDAR

Recently, it was shown that individual tree heights could be accurately estimated using small-footprint airborne light detection and ranging (LiDAR) remote sensing. Because most of the areas studied previously were limited to flat terrain, we investigated the accuracy of LiDAR-derived individual tree height estimates for different types of topographical features in mountainous forests with a steeper and more complex topography. Several middle-aged (40–50 years old) sugi (Cryptomeria japonica D. Don) plantations are found in the mountainous regions in Japan; hence, we chose 48-year-old sugi plantations to investigate the accuracy of these estimates. The surveyed area was divided into three types of topographical features; steep slope (mean slope ± SD; 37.6° ± 5.8°), gentle slope (15.6° ± 3.7°), and gentle yet rough terrain (16.8° ± 7.8°). Before estimating tree heights, the number of detected trees within each topographical feature was researched. In each of these terrains, the percentage of trees detected correctly was 74%, 86%, and 92%; the average error between LiDAR-derived and field-measured tree heights was 0.227m, −0.473m, and −0.183m; and the accuracy of the LiDAR-derived tree height estimates, given as root mean square error (RMSE), was 0.901m, 0.846m, and 0.576m, respectively. Consequently, the procedure presented in this study could detect most canopy trees and estimate individual tree heights with an accuracy better than 1m, even in a forest with a mean slope angle of approximately 38°; thus, indicating that small-footprint airborne LiDAR will be a useful tool for accurately estimating the heights of individual canopy trees in sugi plantations in mountainous areas.