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The authors would like to correct the published article [1], following the detection of editorial mistakes by the main author, as explained below[...]

MacCall, A. D. 2009. Depletion-corrected average catch: a simple formula for estimating sustainable yields in data-poor situations. – ICES Journal of Marine Science, 66: 2267–2271. The depletion-corrected average catch (DCAC) formula is an extension of the potential-yield formula, and it provides useful estimates of sustainable yield for data-poor fisheries on long-lived species. Over an extended period (e.g. a decade or more), the catch is divided into a sustainable yield component and an unsustainable “windfall” component associated with a one-time reduction in stock biomass. The size of the windfall is expressed as being equivalent to a number of years of sustainable production, in the form of a “windfall ratio”. The DCAC is calculated as the sum of catches divided by the sum of the number of years in the catch series and this windfall ratio. Input information includes the sum of catches and associated number of years, the relative reduction in biomass during that period, the natural mortality rate (M, which should be

Current fisheries management policies generally require an assessment of stock status, which is a difficult task when population and fisheries data are limited. Three simple metrics based on catch length compositions (i.e., that reflect exclusive take of mature individuals, P mat; that consist primarily of fish of optimal size, the size at which the highest yield from a cohort occurs, P opt; and that demonstrate the conservation of large, mature individuals, P mega) can be used to monitor population status relative to exploitation. The metrics (collectively referred to as Px ) were intended to avoid growth and recruitment overfishing, but there was no quantitative linkage to stock status and calculation of future sustainable catches. We attempt to make this connection by exploring the relationship of Px measures to fishing mortality and spawning biomass (SB). The relationships are compared specifically to the current target reference point (0.4 times the virgin, or unfished, SB [SB0]) and limit r...

Reasons for performing study: The speed and position data collected by TurfTrax Racing Data Limited during UK Thoroughbred racing have potential to benefit equine science and welfare. The size (the 2006 data set alone consists of 30,932 individual horse starts across 2667 races) and nature (speed and 2D position for each horse at 4 updates per second) of the data make it a unique resource for questions in equine safety, welfare, performance, and animal locomotion. Objective: To determine the accuracy of the TurfTrax tracking system in estimating the speed and position of horses during racing. Methods: Measurements from the TurfTrax wireless tracking system were compared with those of a survey-grade global positioning system (GPS) receiver. Results: The TurfTrax system was found to give position measurements to within +/- 11 and +/- 64 cm in the fore-aft and lateral directions, respectively, averaging +/- 38 cm (interquartile range) and speed to within 0.15 m/s. Potential relevance: The data collected by the TurfTrax system are of sufficient accuracy to inform new diagnoses, training regimens and basic locomotor scientific studies. The position data can provide the precise distance, going, inclination, rate of turn and pack positioning through which each horse has raced. The speed profile can be used to examine the level of exertion, effect of training regimens and influence of racecourse features on performance. A first clinical application would be to analyse retrospectively these factors on occurrence of injury to compare with past training regimens, levels of exertion, and/or racecourse conditions.

Ardron, J. A. 2008. Three initial OSPAR tests of ecological coherence: heuristics in a data-limited situation. – ICES Journal of Marine Science, 65: 1527–1533. As marine protected area (MPA) networks become established worldwide, it will be necessary to track the progress made in meeting the networks’ underlying ecological goals. The 12 coastal European nations of the OSPAR Convention have agreed to establish an “ecologically coherent” network of MPAs within the waters of the Northeast Atlantic by 2010. However, the meaning of ecological coherence has not been explicitly defined, and it has not been explained how it can be assessed. OSPAR’s work on this topic over the past 4 years is summarized here. As the 2010 deadline approaches, the urgency to assess ecological coherence increases. Proper scientific assessment is hampered by the current lack of detailed ecological data, and policy-makers are concerned that collecting data for indicators will tax already limited resources. Unconventional approaches that can make do with what little information is available are being developed, and three initial spatial tests are presented here. A personal perspective of lessons learnt is provided.

PurposeThe purpose of this paper is to identify the causes behind the failures of virtual banks. This work underscores the importance of the differing financial metrics in the virtual and brick and mortar banking channels, when analyzing bank failures.Design/methodology/approach“Probit” analysis on the failed virtual banks and the failed brick and mortar banks revealed that the interest incomes in both banks are significantly different. The non‐interest income and non‐interest expense (NIE) of the surviving banks and the failed banks are explored to examine the causes for failure.FindingsSimilar to previous research it was found that the brick and mortar banks failed due to bad asset quality, but the failure of virtual banks is mainly due to high NIEs. For virtual banks to succeed, the institutions must focus on controlling the burden.Research limitations/implicationsA larger sample size would have been preferable and non‐availability of data limited the scope of the study. Continuing studies could explore the performance of Internet channels of existing brick and mortar banks.Practical implicationsThis study accentuates the importance of the differing business models underlying the two banking channels (virtual banks and brick and mortar banks). These channel specific differences underscore the significance of the financial metrics in operational evaluation.Originality/valueThis is probably the first study to examine the causes of failures of virtual banks and contrast them with brick and mortar banks.

Essentially all published analyses of operational and safety outcomes related to enactment or repeal of the national maximum speed limit (NMSL) were based on data limited to the initial 1-3 years. The purpose of the present study was to collect and analyze longer term speed data.In 2006, traffic speeds were surveyed at 26 locations on urban and rural expressways in five states (California, Montana, Nevada, New Mexico, and Texas) where speeds had been measured in 1996, immediately after repeal of NMSL. Most speed limits were unchanged during the approximately 10-year period. However, Montana introduced a numeric 75 mph limit for passenger vehicles in place of a "reasonable and prudent" limit. In Texas, urban freeway speed limits for passenger vehicles were reduced 5 mph, and truck limits were increased 5 mph.On rural interstates without speed limit changes, travel speeds increased for both passenger vehicles and large trucks; the proportion of passenger vehicles exceeding 80 mph tripled. On rural interstates in Montana where speed limits were lowered for passenger vehicles, travel speeds decreased, even for large trucks whose speed limits had not changed. On urban freeways where speed limits did not change, travel speeds declined somewhat for both passenger vehicles and large trucks; during the study period there also were large increases in traffic volume and development of surrounding areas. On urban freeways in Texas where speed limits declined for passenger vehicles, travel speeds generally decreased, even for large trucks whose speed limits actually had increased.The data suggest that where traffic volumes allow, travel speeds still are increasing 10 years after repeal of NMSL, and many drivers are speeding. The study also shows that speed increases can be curbed and even reversed when speed limits are lowered. Increased enforcement is needed to curb speed increases and the increased risk of serious crashes.

We describe a Bayesian modelling approach to estimate abundance and biomass of pelagic fishes from gillnet catches in data-limited situations. By making a number of simple assumptions, we use fish sustained swimming speed to calculate the effective area fished by a gillnet in a specified soak time to estimate abundance (fish·km -2 ) from the number of fish caught. We used catch data from various sampling methods in northern Australia and elicited anec- dotal information from experts to build a size distribution of the true population to compensate for size classes that were unlikely to be represented in the catch because of size selectivity of the gear. Our final abundance estimates for various-sized scombrids (0.04-4.17 fish·km -2 ) and istiophorids (0.004-0.005 fish·km -2 ) were similar to what has been estimated for similar species in more data-rich situations in tropical regions of the Pacific Ocean. The model is particu- larly useful in data-limited situations in which abundance or biomass estimates are required for pelagic fish species of low economic importance. These data are often required for ecosystem models (e.g., Ecopath) that are increasingly be- ing considered as potential tools for ecosystem-based fisheries management. Resume : Nous presentons une methodologie de modelisation de type bayesien pour estimer l'abondance et la bio- masse de poissons pelagiques a partir de recoltes au filet maillant lorsque les donnees sont limitees. En faisant quel- ques presuppositions simples, nous utilisons la vitesse de nage soutenue des poissons pour estimer la surface effective de capture d'un filet maillant durant une periode donnee de mise en eau afin d'obtenir une estimation de l'abondance (poissons·km -2 ) d'apres le nombre de poissons captures. Nous avons utilise des donnees de capture par differentes me- thodes d'echantillonnage dans le nord de l'Australie et nous avons recueilli des renseignements anecdotiques chez des experts afin d'elaborer une distribution en taille de la population veritable pour compenser l'absence des classes de taille qui risquent de ne pas etre representees a cause de la selectivite des engins de peche. Nos estimations finales d'abondance pour les scombrides (0,04-4,17 poissons·km -2 ) et les istiophorides (0,004-0,005 poisson·km -2 ) de diverses tailles sont semblables aux estimations faites pour des especes semblables des regions tropicales du Pacifique dans des situations ou les donnees etaient plus nombreuses. Notre modele est particulierement utile lorsqu'on veut obtenir des estimations d'abondance ou de biomasse d'especes de poissons pelagiques de faible importance economique et pour lesquelles on possede peu de donnees. Ces informations sont souvent requises dans les modeles d'ecosystemes (par ex., Ecopath) qui sont de plus en plus vus comme des outils potentiels dans la gestion des peches axee sur les ecosystemes.

problems are key roles for the veterinarian. While milk recording and other production data should be central to this process, the work involved in amassing and analysing data limited their use by veterinarians. The recent emergence of specialist software has greatly facilitated access to data. Over 130 large animal practices now use the InterHerd and Herd Companion software packages to evaluate their clients’ herds.

This paper compares several statistical methods for analyzing neural feature selectivity with natural stimuli. Despite the non-Gaussian character of correlations in natural stimuli, several relevant stimulus dimensions can be found by maximizing either information or, as is demonstrated here, variance. In the case of information, the relevance of each dimension is quantified by a Kullback-Leibler divergence between the full input probability distribution and that across inputs associated with positive neural responses, both projected onto that dimension. We demonstrate that least-square matching of the nonlinear prediction based on several dimensions relevant to the recorded spike trains yields an optimization scheme similar to information maximization. The relevant dimensions are found as those that capture the most variance in neural response. The variance along a stimulus dimension is given by a Rényi divergence of order 2 instead of the Kullback-Leibler divergence used for maximizing information. Statistical errors expected for the two schemes are shown to be similar through both analytical and numerical calculations. However, in the asymptotic limit of large spike numbers, maximizing information results in smaller errors than variance optimization. Numerical simulations for model cells with different noise levels show that this trend persists, and possibly increases, when the number of spikes decreases. This makes the problem of finding relevant dimensions one of the examples where information-theoretic approaches are no more data limited than the variance-based measures. Variance and information optimization also outperform methods based on the spike-triggered average for all numbers of spikes and neural noise levels.

An inverse method is developed to determine the optimal stress inversion from imperfect fault data. It is specifically designed to process fault data at variable division—either with observed slip directions or with observed fault/slip senses or with both. The method has the flexibility of processing data with a few fault/slip senses incorrectly determined—a case we occasionally meet in the field. A vast number of artificial 10-datum examples are processed to illustrate the reliability of the method and to examine the effects of the data set at variable division on stress estimation. The results show that the precision of solution decreases with the increase in either of two factors, the percentage of the data limited to slip sense and the range of measurement error, both resulting in a broader dispersion of estimated stress vectors relative to the assigned stress vector in the sigma space. Thus, in order to keep the dispersion within a range of 5° requires the percentage of data for which only slip sense is known to be less than about 20%. This in turn allows for a measurement error range in the data of 10° in real space, much larger than real measurement errors. We believe that the proposed method would be of practical value for stress inversion of fault/slip data.

We demonstrate the process of synchronously combining multiple sources of available fishery information to estimate total abundance in data-limited situations. The application is specific to semelparous populations, such as Pacific salmon, where only data for spawners and recruits are necessary to describe the dynamics of these populations. We apply this technique to summer chum salmon Oncorhynchus keta of the Kuskokwim and Yukon rivers of Alaska. Since 1997, low numbers of returning chum salmon to these rivers have resulted in low harvests, with significant negative economic and social impacts to rural residents of the region. The existing programs for assessing salmon stock in these river basins are inadequate for conventional estimates of total run abundance and the modeling of stock dynamics necessary to derive a quantitative assessment of the returns. Our approach was to utilize the pattern extraction qualities of principal components analysis (PCA) to estimate the underlying trend in escape...

In the article that accompanies this commentary, Staton and Cohen1 present a rational approach to the care of patients with double-hit lymphoma (DHL). The major issues faced in the care of these patients—use of intensive induction regimens, CNS prophylaxis, and transplantation—are all well addressed within the authors’ therapeutic recommendations, which are based on an interpretation of the existing literature. However, the state of the existing literature makes it challenging to propose recommendations for the treatment of DHL and the more common double-expressing lymphoma (DEL). The literature is nearly wholly derived from retrospective studies that are often from single centers. Unlike the broader entity of diffuse large B-cell lymphoma (DLBCL), for which randomized studies have been conducted to determine the optimal treatment regimen, we have virtually no prospective data on which to base treatment recommendations.

The Ngarradj catchment in the Northern Territory of Australia has high temporal resolution rainfall and run-off data from 1998 to 2002. These data have been used to calibrate the DistFW and HEC-HMS hydrology models. The ability of HEC-HMS to be calibrated using an extended hydrograph provided a better basis for long-term modelling. The calibrated HEC-HMS model was applied to 20 years of rainfall from within the region, providing a more reliable estimate of flood frequencies of higher magnitudes (> 1 in 5 year events). However, before undertaking this type of analysis, the modeller must have a good understanding of the catchment system and the limitations of the chosen hydrology model.

It is commonly accepted that sustainable development covers economic, social and ecological aspects and maintains vital exchange process between socioeconomic systems and natural environment. Interdisciplinary subjects emerge as a particular result of sustainable development. Energy planning is one of them. In the past inadequate technologies and inaccessible data limited many research activities. At present great progress is achieved in the fields mentioned above. The cheapest and most precise source of data the is recent register of real estate. Therefore it is possible to design a database for energy planning, where classification criteria could be selected and data could be summarized and structured according to these criteria. The possibilities to use these data would be provided in particular models. Using data processing programs could do it. Some examples are given how databases are used in energy planning and some suggestions how make necessary changes are presented in the article. It is also mentioned what kind of extra data are required to have a multidimensional database. Data are related with data processing programs in order to improve and accelerate accumulation of data. This, in turn, helps using data widely for energy planning. Frist Published Online: 30 Jul 2012

Recent advances allow time‐lapse 3-D (sometimes called 4-D) seismic surveys to map gas‐oil and oil‐water contacts. Some have used “legacy” 3-D data (i.e., data not originally acquired for a 4-D study) and found that the varying quality of the different vintages of the data limited the resolution that could be attained. How then, do we best carry out acquisition and processing for a 4-D seismic program so that the data are repeatable to the extent that differences are attributable to movement of the reservoir fluids and not to the acquisition, processing, or other factors?

A continuing problem in hydrology is the estimation of peak discharges for design purposes on catchments with only limited available data. A promising and elegant approach to this problem is the derived flood frequency curve pioneered by Eagleson (1972, WaterResour. Res., 8(4): 878–898). A number of studies using this approach have been published over the last 20 years but only a few have compared the predicted curves with observations. One exception used a simple stochastic rainfall model to drive a version of TOPMODEL (Beven, 1987, Earth Surf Processes Lardforms, 12: 69–82). The present study describes a new version of the stochastic rainfall simulator previously used with TOPMODEL and its application on three small catchments (1.87, 4.75 and 25.81 km2) in the Jizera Mountains in the Czech Republic. The rainfall model differentiates between high and low intensity events. The resulting rainfall statistics were checked by comparisons with measured data. The flood frequency curves predicted by the combined model were constrained by the regional estimates or a measured series for short return periods and used to predict longer return period flood magnitudes. Only one TOPMODEL parameter has to be adjusted—an effective average transmissivity. For the two smaller catchments also a rainfall parameter has to be adjusted depending on the size of the catchment. It is shown that the random sequence of rainstorms can have a significant effect on the predicted 100 year return period event, even for 1000 year simulations and without allowing for uncertainty in the rainfall model parameters.

Previous analyses of threaded fasteners under vibration are based on static equilibrium conditions with supporting data limited to low frequency loading. Such analyses predict only a net loosening action. This paper presents a dynamic model of a single-bolt assembly with moderate pre-load subjected to axial harmonic vibration. Simulations with this model predict that threaded fasteners can, on the average, loosen or tighten in the presence of vibration; and that the applied vibration, as well as other system parameters, can be tuned so that either action occurs. Measurements from a single-bolt assembly apparatus are presented and compared with the simulations.

The Law of the Sea requires that fish stocks are maintained at levels that can produce the maximum sustainable yield (MSY). However, for most fish stocks, no estimates of MSY are currently available. Here, we present a new method for estimating MSY from catch data, resilience of the respective species, and simple assumptions about relative stock sizes at the first and final year of the catch data time series. We compare our results with 146 MSY estimates derived from full stock assessments and find excellent agreement. We present principles for fisheries management of data-poor stocks, based only on information about catches and MSY.

Background Variability in reporting and classification methods in previous published data of the final dispositions in the rehabilitation of wild raptors makes use of this data limited in trying to audit the quality of the rehabilitation process. Crude as well as stratified disposition rates are needed if quality auditing of the rehabilitation process is to be adequately performed. Methodology Final dispositions of 6221 hospitalized wild raptors admitted at a wildlife rehabilitation centre (WRC) of Catalonia during 1995–2007 were analyzed. These dispositions were calculated as the euthanasia (Er), unassisted mortality (Mr), release (Rr) and captivity rates (Cr)., time to death (Td) for dead and euthanized raptors, and length of stay for released (Tr) raptors was estimated. Stratified analyses by main causes of admission and clinical signs were performed. Results The disposition for the total population were: Er = 30.6%, Mr = 19.1%, Rr = 47.2%, and Cr = 3%. By main causes of admission, Er was higher in the trauma category (34.2%), whereas Mr was found similar between trauma (37.4%) and non-trauma categories (34.8%). The highest Rr was observed for the orphaned group (77.9%). Furthermore, Cr was low in all the categories (

The case is made that the hydrological sciences are data limited and that future progress in understanding hydrological processes is hampered by the lack of adequate data. The future applications of remote sensing to hydrology should provide new types of data that enable hydrologists to address the previously unsolved questions.

This paper uses the Budyko and Fu models to estimate mean annual runoff in 0.05 degrees grid cells across southeast Australia, and assesses the estimates against observations in 323 catchments. The results show that the Budyko model can provide reasonable estimates of runoff and is suitable for data limited regions. In regions where there are some streamfl ow data available, the calibration of a single parameter in the Fu model gives better runoff estimates than the Budyko model and similar to regionalised rainfall-runoff models. In drier regions, the consideration of different vegetation types in the Fu model can improve the modelling results.

A simple method to estimate the parameters of the Ricker stock-recruitment model is described. The method is based on the Beverton and Holt yield per recruit model, as a function of fishing mortality, which can be used to describe the stock-recruitment relationship of an exploited stock even when the data are limited to 1 year of estimates for average biomass and fishing mortality, or, to describe virgin biomass (educated guess). Once the parameters are estimated, the surplus production and maximum sustainable yield can be established. The method is applied to Merluccius gayi of the central zone off Chile and Sardinops sagax off northern Chile. The application of the method is discussed.

The flange inspection associated with piping on offshore production facilities is a time-consuming activity as the flanges should physically be opened in order to perform close visual inspections. In order to sustain maintenance integrity, a number of inspections are allocated for a subsystem based on factors such as: condition of the medium flowing in the line, risk perception of the pipeline system, and the date of installation. Inspection teams recommend inspections based on the data, experience, and exposure to offshore production facilities, as well as the intuition and intentions of those individuals involved with inspection planning and with carrying out implementation during the preventive maintenance shutdowns. However, there is a tendency for the operating company representatives to raise queries with the contractor company representatives about the number of flanges to be opened during the preventive maintenance shutdown as flange inspection consumes a considerable portion of time and resources. Hence, it is vital to interpret sensibly the importance of recommending close visual inspections for flanges if the maintenance integrity is to be sustained. This study focuses on analyzing the historical data limited to flanges on flowlines over the last fifteen years. The final results provide a snapshot of the present status of the flanges of the production facility.Copyright © 2011 by ASME

An Ice Tracking System (ITS) is under development which will automatically extract ice kinematic information from time sequential imagery over Canadian waterways. NOAA AVHRR data are routinely collected at the Ice Centre Environment Canada (ICEC) and are a valuable data source for operational ice analysis and forecasting. For this study AVHRR data were collected between January and February 1992 over the Grand Banks of Newfoundland. The requirement for cloud-free data limited its use. Multiple images over short time intervals were available for a one to two day period, however these were followed by gaps of three to four days. On days when imagery was available synoptic conditions were always similar favouring a southeasterly ice drift. The east coast of Canada is a very difficult ice environment in which to extract accurate ice motion. The ice regime consists mainly of young ice types exhibiting very dynamic behaviour. To the NOAA sensor the ice cover can appear viscous and featureless. The inaccuracies in the extracted ice kinematic information was attributed to positional errors with the input data and the inability of the tracking algorithm to identify correctly the same features on time sequential images. Geocoding inaccuracies, a result of the systematic geocoding process, had an average error of 2.7 km. Algorithm inaccuracies, a result of incorrect matching, had an average error of 2.45 km.

The spill of 2,4,‐D in the Rhine river was used to show the evolution from simple to sophisticated models. The first simulation was done with an analytical solution of the dispersion‐advection equation without elimination. Elimination was introduced in a second simulation. The third simulation was carried out with a numerical model. This included elimination and variable dispersion. The lack of data limited the use of very detailed models.

When two targets are embedded in a temporal stream of distractors, second-target identification is initially impaired and then gradually improves as intertarget interval lengthens (attentional blink; AB). According to bottleneck models of the AB, difficulty of first-target processing should modulate the magnitude of the second-target deficit. To test this, we examined whether a data-limited manipulation of T1 difficulty (forward masking) would modulate AB magnitude. In two experiments, we show that data-limited manipulations of T1 difficulty do affect the AB, so long as T1 is not masked by an immediately trailing distractor. When such a trailing item is present, the relationship between T1 difficulty and the AB disappears.

There has been speculation that trends in syphilis have been fueled by crack cocaine use. This study examined the data on syphilis notifications and arrestee drug abuse monitoring (ADAM) to ascertain the relationships between syphilis and cocaine use trends in three racial/ethnic groups. Syphilis notifications and data from the ADAM project were compared in Houston/Harris County, Texas, from 1991-1998 using a linear regression equation. Data indicated significant relationships between the data for cocaine use and syphilis in African Americans but not Hispanics or non-Hispanic whites. For African Americans, 58% of the variance between cocaine use and syphilis was explained. When data limited to jail syphilis notifications and ADAM cocaine in African Americans were examined, the association was stronger for males than for females. For African Americans, cocaine (probably crack cocaine) use trends were significantly associated with syphilis trends in this population. These data suggest that control of crack cocaine may have an impact on syphilis rates and that there may be close relationships between some STDs and drug abuse.

Abstract The repeatability of seismic data acquisition and processing has become an important question in determining the role of conventional land, marine, and transition zone systems in seismic monitoring of reservoirs. In this paper we examine a case study involving two repeated 3-D seismic surveysacquired using an ocean bottom cable (OBC) system. Although not originally acquired as part of a monitoring project, the survey design and preplanned source and receiver patterns were identical over a significant area. Even thoughthere were slight differences in the source and receiver positions, the final fold, offset and azimuth distributions were very similar. We also found, not surprisingly, that since the two surveys had some differences in acquisition and processing, "off-the-shelf' final migrated data volumes showed significant differences, which could only be slightly reduced by the use of matching filters. However, by careful reprocessing of the prestack data with a sequence designed to maximize repeatability of the signal, the differences were reduced dramatically. The areal distribution of the dual-sensorsummation scalars for the base and monitoring surveys were found to be similar. We also found that small phase differences can give large amplitude differences and that it isessential to account for known differences such as instrument responses and noise characteristics at the start of prestack reprocessing. The level of repeatability required for a givenmonitoring project depends on the specifics of the reservoir and the monitoring goals; however, in this case, repeatability achieved between the two data volumes, after careful prestack reprocessing, indicates that OBC data would be suitable foranalysis of reservoir fluid movement. Introduction There has been a resurgence of interest lately in using repeated seismic surveys as a reservoir description and production monitoring tool. Although studies of repeated seismic surveysfor mapping steam fronts go back more than 10 years, recent advances have extended time lapse or 4-D seismic to map gasoil and oil-water contacts with significant economic benefit1,2,3,4. Recent studies by Watts et al.5, have made fortunate use of legacy 3-D data not originally acquired for a 4-D study and found that the varying quality of the different vintages of 3-D data was a factor limiting the resolution of their studies. As a result, the question arises how best to carry out the data acquisition and processing for a 4-D seismicprogram so that the data are repeatable to the extent that differences are attributable to movement of the reservoir fluidsrather than acquisition and processing or other factors. Preliminary results from a case study of repeatability of the ocean bottom cable (OBC) system based on two collocated 3-D surveys acquired and processed independently werepresented by Beasley et al.6 They showed that "off-the-self' final migrated data volumes have significant differences andthat careful reprocessing of the prestack data to account for known differences was necessary to improve differencing results. This paper will summarize previous results and discuss observations and conclusions derived whilereprocessing the data.

Limited data are a common challenge posed to fisheries stock assessment. A simulation framework was applied to examine the impact of limited data and data type on the performance of a widely used catch-at-age stock-assessment method (Stock Synthesis). The estimation method provided negatively biased estimates of current spawning-stock biomass (SSB) relative to the unfished level (final depletion) when only recent survey indices were available. Estimation of quantities of management interest (unfished SSB, virgin recruitment, target fishing mortality and final depletion) improved substantially even when only minimal-length-composition data from the survey were available. However, the estimates of some quantities (final depletion and unfished SSB) remained biased (either positively or negatively) even in the scenarios with the most data (length compositions, age compositions and survey indices). The probability of overestimating yield at the target SSB relative to the true such yield was ~50%, a risk-neutral result, for all the scenarios that included length-composition data. Our results highlight the importance of length-composition data for the performance of an age-structured assessment model, and are encouraging for the assessment of data-limited stocks.

EDITOR—In their editorial on life without COX 2 inhibitors Shaughnessy and Gordon give examples of drug and non-drug measures shown to be effective in osteoarthritis, but their discussion of opioids was not referenced.1 The omission of studies supporting the use of opioids was surprising, particularly when references for the non-drug measures were included even when the effect sizes were small or the data limited by small …

PubMed provided the primary data source and was supplemented by a manual search of reference lists from relevant papers and books. Studies were included if they met the following inclusion criteria: all participants were Caucasian; only agenesis in the permanent dentition was considered; congenital absence was diagnosed clinically and radiographically; study participants had been selected randomly; study participants were >3 years old; and sample size was >1000. Data were extracted to calculate the overall prevalence of agenesis (no. children with >1 missing tooth/total no. in sample), the prevalence in boys versus girls, and the proportion of agenesis by tooth type. This information was then plotted chronologically. In total, 19 articles from the literature search met the inclusion criteria. The earliest published paper (1936) revealed a prevalence of 3.4%, whereas the most recent paper (1993) revealed a prevalence of 6.5%. Prevalence of agenesis varied from a low of 0.1% (1943) to a high of 10.1% (1973). Where gender differences were considered, girls were reported to have more agenic teeth than boys. Although the time period is short and the data limited it would appear that hypodontia has been diagnosed more often in more recent studies.

To reveal the relation between snow melting and landslide occurrence, we developed an automated observation system using a handheld computer in 1987. However, the quality and quantity of data limited processing in this system. To solve these problems, we designed a new automated data acquisition system in 1991. We report here the outline of this system, improved points, new problems during one year of operation with the new system.

This paper analyzes the effect on performance when several active processes compete for limited processing resources. The principles discussed show that conclusions about the interactions among psychological processes must be made with caution, and some existing assumptions may be unwarranted. When two (or more) processes use the same resources at the same time, they may both interfere with one another, neither may interfere with the other, or one may interfere with a second without any interference from the second process to the first. The important principles are that a process can be limited in its performance either by limits in the amount of available processing resources (such as memory or processing effort) or by limits in the quality of the data available to it. Competition among processes can affect a resource-limited process, but not a data-limited one. If a process continually makes preliminary results available even before it has completed all its operations, then it is possible to compute performance-resource operating characteristics that show how processes interact. A number of experiments from the psychological literature are examined according to these processing principles, resulting in some new interpretations of interactions among competing psychological processes.

Although a number of models have been suggested for relating the coefficient of friction of a surface with its profile characteristics, no firm experimental evidence to support a specific theory has been reported. In this work, the methods commonly used to calculate the characteristics of slope and curvature of a surface are investigated. The limitations of these methods are discussed and a new method for calculating the slopes and curvatures of a surface is recommended and shown to provide the most unbiased estimate for data limited by probe size. Finally, the results from preliminary tests show that the slope characteristics calculated using this technique are related to the friction coefficients of a surface as suggested by Challen et al. (1).

Micro-meteorological data acquired during five expeditions to carefully chosen sites are analysed to determine the flux-gradient relation for the transfer of heat and water vapour in the lower atmosphere. The analysis takes the form of a direct assessment of the Monin-Obukhov universal functions φH and φW. Data for φH were available from all five expeditions, and for φW from two of these. It was found that φH = φW over the whole of the z/L range available, indicating an identity in mechanism for the turbulent transport of heat and water vapour over a freely evaporating surface. Over the range 0.02 0.2, φH was found to vary as |z/L|−1/2. Insufficient data limited the value of the corresponding analysis for φW Excellent agreement was found between the φH and φW data, and φ-curves assessed from a previous shape-function analysis (Swinbank and Dyer 1967). The empirical relation φ = (1–15 z/L)−0·55 agrees with the experimental values of φH and φW over the whole of the |z/L| range to within a few per cent, thus permitting numerical evaluation of φ.