Restricted Procedure Research Articles

A column generation method for the multiple-choice multi-dimensional knapsack problem

In this paper, we propose to solve large-scale multiple-choice multi-dimensional knapsack problems. We investigate the use of the column generation and effective solution procedures. The method is in the spirit of well-known local search metaheuristics, in which the search process is composed of two complementary stages: (i) a rounding solution stage and (ii) a restricted exact solution procedure. The method is analyzed computationally on a set of problem instances of the literature and compared to the results reached by both Cplex solver and a recent reactive local search. For these instances, most of which cannot be solved to proven optimality in a reasonable runtime, the proposed method improves 21 out of 27.

Genetic Parameters and Annual Trends for Birth and Weaning Weights of a Northeastern Thai Indigenous Cattle Line

Records of a Northeastern Thai indigenous cattle line population were used to estimate genetic parameters and annual trends for calf weights. The data set comprised records of 1,922 and 1,489 animals for birth and weaning weight, respectively born from 1993 to 2004. A bivariate analysis was carried out for variance and covariance components estimations using average information restricted maximum likelihood procedure. Average estimated breeding value and maternal breeding value of the animals born in 1993 were set to zero as a base group. Genetic trends of each trait were calculated by regressing average estimated breeding values and maternal breeding values on birth year of calves. Phenotypic trends for each trait were calculated by regressing the yearly adjusted weight on birth year of calves. The results revealed that the estimate of direct heritability, maternal heritability and maternal permanent environmental variance as a proportion of phenotypic variance for birth and weaning weight was 0.40, 0.14 and 0.04; 0.27, 0.05 and 0.23, respectively. Direct heritability was moderately heritable and genetic improvement through selection can be achieved. The estimate of phenotypic, direct genetic, maternal genetic and maternal permanent environmental correlation between birth and weaning weight was 0.48, 0.65, 0.98 and 0.73, respectively. The phenotypic trend, genetic trends of estimated breeding value and maternal breeding value for birth weight was 0.18, 0.04 and 0.01 kg/year, respectively. The phenotypic trend, genetic trends of estimated breeding value and maternal breeding value for weaning weight was -1.36, 0.32 and 0.03 kg/year, respectively. As maternal genetic effect was considerably less important than direct genetic effect, selection for improved weaning weight of this Northeastern Thai indigenous cattle line can place more emphasis on the direct genetic effect.

Likelihood ratio tests for equality of shape under varying degrees of orientation invariance

We consider a problem from image cytometry where the objective is to describe possible changes in the shape and orientation of cellular nuclei after treatment with a toxin. The shapes of nuclei are represented by individual ellipses. It is argued that the shape comparison problem can be formulated as a generalization of a hypothesis test for the equality of covariance matrices. For many cell types, the test statistic should be invariant with respect to orientations of the cells. For other cell types, the test statistic should be equivariant with respect to orientations of the cells, but invariant with respect to orientations of the images. Likelihood ratio tests (LRTs) are derived under a Wishart model. The likelihood maximization uses a new result about the minimization of the determinant of a sum of matrices under individual rotations. The applicability and limitations of these LRTs are demonstrated by means of simulation experiments. The reference distributions of the test statistics under the null hypothesis are obtained using unrestricted and restricted randomization procedures. Justification for the Wishart model is provided using a residual diagnostic method. The scientific implications of the results are considered.

豚の系統造成における希望改良量を達成するための選抜手法の比較

豚の系統造成における希望改良量を達成するための選抜手法の比較

Heritability estimates and correlations between production and reproductive traits in Lori-Bakhtiari sheep in Iran

Heritablities and correlations were estimated between lamb body weight at different ages and reproductive traits in the Lori-Bakhtiari sheep breed. Data and pedigree information for Lori-Bakhtiari sheep used in this study were 5826 records of body weight of lambs from 240 sires and 1627 dams, and 5741 records of reproductive traits from 1797 ewes collected from 1989 to 2006 from a Lori-Bakhtiari flock at the Shooli station in Shahrekord. The lamb traits investigated were weights at birth (BWT), weaning (WWT) and at six months of age (WT6). The reproductive traits were conception rate (CR), litter size at birth per ewe lambing (LSB/EL), litter size at weaning per ewe lambing (LSW/EL), litter size at birth per ewe exposed to a ram (LSB/EE), litter size at weaning per ewe exposed (LSW/EE), total litter weight at birth per ewe lambing (TLWB/EL), total litter weight at weaning per ewe lambing (TLWW/EL), total litter weight at birth per ewe exposed (TLWB/EE) and total litter weight at weaning per ewe exposed (TLWW/EE). (Co)Variance components and genetic parameters were estimated using the restricted maximum likelihood procedure applying three multi-trait animal models. The estimates of direct heritability for lamb body weights were 0.31 ± 0.02 at birth, 0.10 ± 0.02 at weaning and 0.19 ± 0.02 at six months of age, and estimates of maternal heritability were 0.22 ± 0.02, 0.16 ± 0.02 and 0.04 ± 0.02, respectively. The estimates of heritability for reproductive traits varied from 0.02 ± 0.01 for CR to 0.23 ± 0.01 for TLWB/EL, and repeatability estimates for reproductive traits ranged from 0.11 for CR to 0.28 for LSB. Genetic correlations among lamb body weight and various reproductive traits were positive and varied from 0.06 to 0.98. Phenotypic correlations were lower than genetic correlations (0.01 to 0.20). The estimates of genetic correlations between lamb body weight with CR and litter size at birth and at weaning were low to moderate, while those between lamb body weight with TLBW and TLWW per ewe lambing and per ewe exposed were positive and very high. Thus, lamb body weight at weaning or at six months of age could be considered as selection criteria to indirectly improve reproductive traits in Lori-Bakhtiari sheep because the heritability of lamb body weight was more than that of reproductive traits and can be measured at an early stage in the life of the animal. Keywords : Genetic correlations, early growth traits, reproductive traits South African Journal of Animal Science Vol. 38 (2) 2008: pp. 110-118

Integration of Temporal Information Across Trials in EEG Data Analysis

Event Abstract Back to Event Integration of Temporal Information Across Trials in EEG Data Analysis Matthias Ihrke1, 2*, Hecke Schrobsdorff1, 2 and Michael J. Herrmann1, 3 1 BCCN , Germany 2 Max-Planck-Institute for Dynamics and Self-Organization, Germany 3 University of Edinburgh, Germany We propose an averaging method for segments of electrophysiological data (Event-Related Potentials, ERPs) that has been specifically designed to compensate for processing speed in different realizations of the same experiment in individual subjects. The algorithm is based on the estimation of single-trial ERPs by wavelet-denoising combined with a parametrized dynamic time-warping algorithm to guide selective averaging. The hierarchical averaging scheme is based on dendrograms generated by agglomerative cluster-analysis. External knowledge about the temporal alignment of cognitive processing steps is incorporated by using time-markers of observable events (e.g. saccades, response-markers) by independently combining corresponding segments between to time-markers. This method has several advantages over previous averaging schemes: (i) the questionable assumption of an identical ERP signal in different realizations is dropped and different processing speeds are considered explicitly, (ii) the choice of the warping function is estimated from the data and does not require an a priori specification as in [1] and (iii) external knowledge in the form of arbitrarily many time-markers can be integrated. A cross-validation approach is taken to estimate optimal parameter-settings for the restricted timewarping procedure and to contrast the procedure with other relevant averaging schemes. We define the average temporal distortion as the measure obtained by averaging warping functions computed on all pairs of trials independently. We find that electrodes are well divisible into distinct regions of physically neighbouring electrodes applying cluster-analysis with this measure. This indicates that the timecourse of cognitive processing as measured by the structure and distribution of the ERP's components are independent in different brain regions. A software library written in the C-programming language (with partial Matlab-support) that implements the described algorithms is available from http://www.bccn-goettingen.de/projects/libeegtools.

Genetic parameters of body weight and fat-tail measurements in lambs

The data set used in this study was body weight of 5418 lambs at weaning, 4234 lambs at 6 months of age collected during 1989–2006, fat-tail measurements of 1205 lambs at 3 months of age and 988 lambs at 6 months of age recorded over a 4-year period (2003–2006) from a Lori-Bakhtiari research flock at the Shooli sheep breeding station in Shahrekord. Fat-tail measurements were upper fat-tail width (UFTW), lower fat-tail width (LFTW), fat-tail length (FTL), fat-tail gap length (FTGL), fat-tail depth (FTD) and upper fat-tail circumference (UFTC). (Co)variance components and genetic parameters were estimated using restricted maximum likelihood procedure and multi-trait animal model. The model included the fixed effects of year of birth, age of dam, sex of lamb, type of birth, body condition score (only for fat-tail measurements) and age of lamb (days) as covariate, and random effects direct additive genetic, maternal additive genetic and residual. The estimates of direct heritability of body weight and fat-tail measurements at 3 months of age varied from 0.11 ± 0.02 for body weight to 0.25 ± 0.06 for FTL, while the direct heritability of considered traits at 6 months of age were higher and ranged from 0.19 ± 0.03 for body weight to 0.36 ± 0.06 for FTL. The estimates of maternal heritability were lower than direct heritability except for body weight at 3 months of age, and decreased with age of lambs. Genetic correlations among body weight and various fat-tail measurements were positive and varied from low to very high. The genetic parameter estimates obtained for body weight and fat-tail measurements indicated that genetic improvement through selection could be possible for reducing fat-tail size, but single-trait selection for measurements of fat-tail causes some decrease in body weight due to correlated response to selection. Thus, because genetic correlations were not perfect, even with positive genetic correlations between body weight and fat-tail measurements, it is possible to increase body weight and reduce fat-tail size by multi-trait selection.

Nitrogen Status of Pollen Donor Affects Kernel Set and Yield Components in Corn

ABSTRACT Nitrogen (N) status of corn plants influences yield performance through adjustment of yield components. Physiological function of corn pollen produced under N-stressed conditions has not drawn enough attention in genotype selection and breeding programs. The object of this study was to assess effects of N nutrition of the pollen donor on kernel set and yield components of the pollen recipient in a field trial by using a restricted pollination procedure. Pollen from plants receiving 0 and 240 kg N ha−1 was manually applied to plants receiving 0, 80, 160, and 240 kg N ha− 1 during silk emergence. The high rate of N fertilizer applied to the pollen donor significantly increased kernel number, kernel weight, harvest index, and aboveground biomass in the pollen recipient. The effect of N nutrition of the pollen donor was similar at all N levels that were applied to the pollen recipient so the interaction was not significant for any of the variables.

Assessment of cord blood hematopoietic cell parameters before and after cryopreservation

The testing of cord blood (CB) progenitor and stem cell units for transplantation suitability involves enumeration of total nucleated cells before freezing. CD34+ cell counts may also be a means of determining suitability. Studies have been conducted to evaluate how specific storage conditions influence cell counts. CB units were processed by hydroxyethyl starch volume reduction. Cryopreserved-thawed samples were diluted 1:3 without washing. CD34+ cells were measured with three commercially available assay methods. In specific studies, apoptosis-indicating reagents were included. CB units were analyzed for nucleated cells, aldehyde dehydrogenase-containing cells, and progenitor colonies. CD34+ cell levels and nucleated cells were retained during storage in test tubes at 1 to 6 degrees C for 3 days. Cryopreserved-thawed samples showed a reduction in CD34+ cells relative to prefreeze levels with the largest decrease with the Stem-Kit (Beckman Coulter) restricted gating procedure. Prefreeze samples contained minimal numbers of presumed apoptotic cells detected with 7-aminoactinomycin D or SYTO16, but after cryopreservation-thawing there was an increase. Nucleated cell levels determined with a hematology analyzer or flow cytometry were reduced after thawing. Cryopreservation-thawing reduced the percentage of CD34+ cells positive for the presence of aldehyde dehydrogenase and the number of progenitor colonies. These differences were significant. These studies indicate that CD34+ cell counts were maintained when CB samples were stored at 1 to 6 degrees C in test tubes for 3 days. Cryopreservation-thawing resulted in changes in a number of parameters including the percentage of CD34+ cells that were aldehyde dehydrogenase(+) and the number of 7-aminoactinomycin D(+) cells and SYTO16(low) cells.

Fitting a multisite daily rainfall model to New Zealand data

This study considers a generalisation of a multisite daily rainfall generation model originally proposed by Wilks (1998) [Wilks, D.S., 1998. Multisite generalization of a daily stochastic precipitation generation model. J. Hydrol. 210, 178–191.] in the context of weather simulation. This particular model is reformulated as a hidden Markov model and its properties are determined. Maximum likelihood estimation procedures are developed, including the EM (Expectation-Maximisation) algorithm, as well as simple method of moments estimation procedures that build on those proposed in Wilks (1998). A restricted maximum likelihood procedure is also proposed as a computationally efficient and practical strategy for fitting the general model, providing consistent and reliable estimates of the model parameters that typically show small differences when compared to full maximum likelihood. The fully-parameterised model and the Wilks reduced form of the model are fitted to selected New Zealand rainfall data and their performance assessed. The Wilks model was not generally favoured over the fully-parameterised model except for a few months mainly associated with the drier months during the austral summer. In the light of this experience, further research developments and initiatives are highlighted.

Genetic determination of mothering ability and piglet growth in indigenous Mukota sows of Zimbabwe

The objective of this study was to determine genetic parameters of individual and sow records on litter size and weights at 21 and 35 days in Mukota pigs. Data gathered from 1961 pigs at the University of Zimbabwe between January 1998 and August 2003, were analysed. Individual pig traits analysed were the weight at 21 days of age (THRWT), weight at weaning (WWT) and average daily gain from birth to weaning (ADGWW). Sow performance traits considered were the litter weight after 21 days (LTHRWT), litter weight at weaning (LWWT), number of pigs weaned (NW) and mothering ability (MA). An animal model was used to estimate genetic parameters using the average information restricted maximum likelihood procedure. Individual pig records were analysed using models with or without litter effects and maternal genetic effects. Incorporating the maternal genetic variance component drastically reduced the standard errors of the heritability estimates. The heritabilities for LTHRWT, LWWT and MA were 0.18, 0.15 and 0.05, respectively. The LWWT and NW were positively correlated. There were no genetic relationships between MA and LTHRWT and LWWT. No antagonisms should be expected when selecting for MA and increasing litter weights in Mukota pigs.

Two-component Poisson mixture regression modelling of count data with bivariate random effects

Two-component Poisson mixture regression is typically used to model heterogeneous count outcomes that arise from two underlying sub-populations. Furthermore, a random component can be incorporated into the linear predictor to account for the clustering data structure. However, when including random effects in both components of the mixture model, the two random effects are often assumed to be independent for simplicity. A two-component Poisson mixture regression model with bivariate random effects is proposed to deal with the correlated situation. A restricted maximum quasi-likelihood estimation procedure is provided to obtain the parameter estimates of the model. A simulation study shows both fixed effects and variance component estimates perform well under different conditions. An application to childhood gastroenteritis data demonstrates the usefulness of the proposed methodology, and suggests that neglecting the inherent correlation between random effects may lead to incorrect inferences concerning the count outcomes.

Promoting a Culture of Patient Safety

Patient safety and medical error reduction are topics of extreme importance. Although there has been considerable media controversy regarding reports of decreased patient safety and errors that have occurred in operating rooms of hospitals, ambulatory surgery centers, and doctors' offices, the majority of data across various specialties demonstrate a very low incidence of adverse events resulting from office-based surgery. Limited research has been conducted in patient safety on the topic of outpatient surgery. Since the release of the Institute of Medicine's (IOM) report To Err Is Human, significant progress has been made in patient safety. According to the IOM's report in 2000, between 48,000 and 98,000 annual US hospital deaths result from medical errors. Following the report, there have been numerous calls to improve patient safety and place it at the forefront of the national agenda. The Florida Board of Medicine restricted office procedures in 2000 after a series of incidents occurred in the outpatient setting. The objectives of this paper are to review the Florida moratoria data over the last 6 years to discuss what we have learned as a specialty and to continue a culture of safety in plastic surgery. One of the remaining challenges is the need to continually improve this culture of safety and emphasize the need for continued patient education, specifically related to esthetic procedures administered in nonclinical settings by amateur, unlicensed, or unqualified practitioners, with a misrepresentation of their credentials and training. This is a long-term proposition and one that has been driven foremost by our leaders in plastic surgery.

Genetic parameters and trends for production and reproduction traits in Thai Landrace sows

Abstract Data from Thai Landrace sows were used to estimate the genetic parameters and trends for production and reproduction traits, over the first four parities. The reproduction traits investigated were age at first conception (AFC), total number of piglets born per litter (TB) and weaning to first service interval (WSI). The reproduction data was gathered from 9194 litters born between 1993 and 2005. The production measures were average daily gain (ADG) and backfat thickness (BF). These were recorded from 4163 boars and 15 171 gilts. Analyses were carried out using a multivariate animal model inputting average information restricted maximum likelihood procedures. Heritability estimates on the reproduction traits for AFC was 0.21, for TB in the first four parities it ranged from 0.02 to 0.11 and for WSI over the first three parities it ranged from 0.16 to 0.18. Heritability estimates for production traits were: 0.31 (ADG) and 0.45 (BF). AFC was genetically correlated favorably with TB (− 0.48) and WSI (0.35) in the first parity. Genetic trends were 4.71 g, − 0.23 mm and 0.23 days per year for ADG, BF and AFC respectively. There was no genetic progress for the other traits. It was concluded that selection for low AFC will increase TB and decrease WSI. The results further revealed that the ongoing selection being used improved growth rate and reduced backfat thickness. However, there was no genetic improvement in TB.

A New Proposal for Setting Parameter Values in Restricted Randomization Methods

Complete randomization could result in an undesirable imbalance in the number of patients assigned to each treatment, especially in small trials. Therefore, a variety of restricted randomization procedures has been developed. By varying parameters it is possible to appropriately modify the balancing characteristics of these designs. However, there is little information on what are sensible choices for the parameters. Therefore, we suggest a new method for suitable determination of parameter values of restricted randomization rules. For restriction to be effective, it need not yield exact equality. As the reliability of a test is not very sensitive to slight deviations from equal sample sizes we define that a given maximum tolerable imbalance d can be achieved or exceeded with a given probability p(*). By using this condition, parameter values of restricted procedures are determinable. For permuted-block, biased-coin, urn, and big-stick randomization we investigated the impact of parameters on balancing properties. For different extents of restriction and by using the submitted condition, the values of parameters to be chosen are determined. Up to now choice of parameter values has often occurred at random. Now it is possible to determine values of parameters by specifying the tolerable degree of imbalance and the risk to be worse. As a consequence restriction will, as much as possible, not be imposed and not imposed more than necessary in order to preserve the intrinsic quality of randomization.

Genetic and phenotypic parameters for test day milk yield of Sahiwal cattle in the semi-arid tropics

A total of 19 376 test day (TD) milk yield records from the first three lactations of 1618 cows daughters of 162 sires were used to estimate genetic and phenotypic parameters and determine the relationship between daily milk yield and lactation milk yield in the Sahiwal cattle in Kenya. Variance components were estimated using animal models based on a derivative free restricted maximum likelihood procedure. Variance components were estimated using various univariate and multi-trait fixed regression test day models (TDM) that defined contemporary groups either based on the year-season of calving (YSCV) or on the year-season of TD milk sampling (YSTD). Variance components were influenced by CG which resulted in differences in heritability and repeatability estimates between TDM. Models considering YSTD resulted in higher additive genetic variances and lower residual variances compared with models in which YSCV was considered. Heritability estimates for daily yield ranged from 0.28 to 0.46, 0.38 to 0.52 and 0.33 to 0.52 in the first, second and third lactation, respectively. In the first and second lactation, the heritability estimates were highest between TD 2 and TD 4. Genetic correlations among daily milk yields ranged from 0.41 to 0.93, 0.50 to 0.83 and 0.43 to 86 in the first, second and third lactation, respectively. The phenotypic correlations were correspondingly lower. Genetic correlations were different from unit when fitting multi-trait TDM. Therefore, a multiple trait model would be more ideal in determining the genetic merit of dairy sires and bulls based on daily yield records. Genetic and phenotypic correlations between daily yield and lactation yields were high and positive. Genetic correlations ranged from 0.84 to 0.99, 0.94 to 1.00 and 0.94 to 0.97 in the first, second and third lactations, respectively. The corresponding phenotypic correlation estimates ranged from 0.50 to 0.85, 0.50 to 0.83 and 0.53 to 0.87. The high genetic correlation between daily yield and lactation yield imply that both traits are influenced by similar genes. Therefore daily yields records could be used in genetic evaluation in the Sahiwal cattle breeding programme.

Genetic and phenotypic parameters and annual trends for milk production and fertility traits of the Sahiwal cattle in semi arid Kenya

Data comprising 7211 lactation records of 2894 cows were used to estimate genetic and phenotypic parameters for milk production (lactation milk yield, LMY and lactation length, LL) and fertility (calving interval, CI; number of services per conception, NSC and age at first calving, AFC) traits. Genetic, environmental and phenotypic trends were also estimated. Variance components were estimated using univariate, bivariate and trivariate animal models on based restricted maximum likelihood procedures. Univariate models were used for each trait, while bivariate models were used to estimate genetic and phenotypic correlations between milk production and fertility traits and between LMY, LL, CI and NSC within each lactation. Trivariate models were used in the analysis of LMY, LL, CI and NSC in the first three lactations. Heritability estimates from the univariate model were 0.16, 0.07, 0.03, 0.04 and 0.01 for LMY, LL, CI, AFC and NSC, respectively. The heritability estimates from trivariate analysis were higher for milk production traits than those from univariate analyses. Genetic correlations were high and undesirable between milk production and fertility traits, while phenotypic correlations were correspondingly low. Genetic trends were close to zero for all traits, while environmental and phenotypic trends fluctuated over the study period.

Genetic variation in serum copper concentration in Angus cattle

AbstractFollowing the discovery of low serum copper (Cu) concentrations in 9-month-old beef calves at pasture in autumn (50% of animals had values <7·5 μmol/l), genetic variation in serum Cu concentration was studied in an experimental Angus herd in New Zealand, monitoring at intervals from about 7 to 17 months of age. The study was initiated in autumn when animals were supplemented with zinc (Zn) salts (to protect against liver injury from toxin-producing facial eczema spores on the pasture), and later in the production year after Cu supplementation but without Zn supplementation. Heritabilities of Cu concentration were estimated in 837 calves from six calf crops, the progeny of 47 sires, using restricted maximum likelihood procedures with an animal model. Correlations between Cu concentration and Zn concentration were also estimated, along with correlations between Cu concentration and 6-month, 9-month and yearling live weights. The heritability estimate for Cu concentration at all times outside the autumn Zn supplementation period was 0·28±0·08 (between-animal repeatability, 0·30±0·05), and the heritability estimates for autumn Cu concentration and Zn concentration were 0·35±0·11 and 0·26±0·13, respectively. The genetic and environmental correlations between autumn Cu concentration and Zn concentration were ?0·29±0·31 and 0·15±0·11, respectively, suggesting antagonistic effects between Zn and Cu only at the genetic level, with a net (phenotypic) correlation of 0·02±0·06. Genetic correlations between Cu concentration (outside the autumn season) and 6-month, 9-month and yearling weights ranged from 0·15±0·15 to 0·17±0·16. It was concluded that serum Cu and Zn concentrations in calves were heritable traits under the grazing conditions encountered, and that index selection to increase live weights and Cu concentrations could be applied if desired.

Genetic parameter estimates for body weight in local Venda chickens

Genetic parameters were estimated for Venda chicken body weights at hatching, and at 4 weeks, 10 weeks and 21 weeks of age. A single-trait animal model with restricted maximum-likelihood procedures was used. Random effects were additive direct and maternal genetic, common environmental and error. The heritability estimates for direct effects were 0.36, 0.25, 0.41 and 0.22 for hatch, 4 weeks, 10 weeks and 21 weeks, respectively. The maternal effects were estimated at hatch and 4 weeks of age and were not present at later ages. Common environmental effects disappeared with increasing age. There was an antagonistic relationship between direct and maternal effects. The results show potential for genetic improvement of indigenous Venda chickens through selection. Maternal effects should be considered if selection is carried out at early ages.

Office Surgery Safety: The Myths and Truths behind the Florida Moratoria???Six Years of Florida Data

Office-based surgery is an important method of health care delivery, and in 2000, the Florida Board of Medicine restricted office procedures. The objective of this study was to analyze the deaths resulting from office procedures in Florida. The authors reviewed all office surgical incidents that resulted in death, injury, or hospital transfer in Florida from January of 2000 to January of 2006. Various methods were used to determine board status, office accreditation, and hospital privileges. In 6 years of Florida data, a total of 46 deaths related to office procedures were reported. Twenty of those were surgical procedures that are within the scope of plastic surgery, although non-board-certified plastic surgeons performed nine. Of those 20 related to plastic surgery, 11 died before discharge. Although all 11 survived long enough to be transferred to a hospital, we classified them as office deaths. The other nine died after appropriate discharge. Of the nine, seven deaths were from thromboembolism and the others from unknown causes. Thirty-five deaths were related to non-board-certified plastic surgeons and specialists in other fields. Board-certified plastic surgeons accounted for less than one-fourth of the deaths. There were no deaths from a board-certified plastic surgeon since April of 2004. There were over 600,000 operations during the study period. The fact that 11 office deaths were reported would suggest that the location in which these procedures were performed was not as much of a factor as the regulators have suggested. The most frequent cause of death after discharge was thromboembolism.