Different Datasets (different + dataset)

Distribution by Scientific Domains

Selected Abstracts

Annual Rainfall and Seasonality Predict Pan-tropical Patterns of Liana Density and Basal Area

BIOTROPICA, Issue 3 2010
Saara J. DeWalt
ABSTRACT We test the hypotheses proposed by Gentry and Schnitzer that liana density and basal area in tropical forests vary negatively with mean annual precipitation (MAP) and positively with seasonality. Previous studies correlating liana abundance with these climatic variables have produced conflicting results, warranting a new analysis of drivers of liana abundance based on a different dataset. We compiled a pan-tropical dataset containing 28,953 lianas (,2.5 cm diam.) from studies conducted at 13 Neotropical and 11 Paleotropical dry to wet lowland tropical forests. The ranges in MAP and dry season length (DSL) (number of months with mean rainfall <100 mm) represented by these datasets were 860,7250 mm/yr and 0,7 mo, respectively. Pan-tropically, liana density and basal area decreased significantly with increasing annual rainfall and increased with increasing DSL, supporting the hypotheses of Gentry and Schnitzer. Our results suggest that much of the variation in liana density and basal area in the tropics can be accounted for by the relatively simple metrics of MAP and DSL. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp [source]

Heroin users in Australia: population trends

C. YALÇIN KAYA Senior Lecturer
Abstract The aim of this paper is to identify certain important population trends among heroin users in Australia for the period 1971 , 97, such as: population growth, initiation, i.e. the number who were initiated to heroin in a given year, and quitting, i.e. the number that quit using heroin. For this purpose, we summarize and extract relevant characteristics from data from National Drug Strategy Household Survey (NDSHS 1998) conducted in Australia in 1998. We devise a systematic procedure to estimate historical trends from questions concerning past events. It is observed from our findings that the size of the heroin user population in Australia is in a sharp increase, especially from the early 1980s onwards. The general trend obtained for the period 1971 , 97 is strikingly similar to that obtained by Hall et al. (2000) for the dependent heroin user population in Australia, even though their study was based on different datasets and a different methodology. In our reconstruction of the time history we also detect a levelling-off prior to 1990. Initiation is also observed to be on a sharp increase. The latter trend is accompanied by a similar trend of quitting, perhaps indicating a relatively short heroin use career. A sharp decrease in both initiation and quitting is observed after 1990. In conclusion, in the case of the trend in the population of heroin users a high rate of growth has been identified that is consistent with the existing literature. In the process, we demonstrated that even a static survey such as NDSHS 1998 can, sometimes, be used to extract historical (dynamic) trends of certain important variables. [source]

Semantic confusion regarding the development of multisensory integration: a practical solution

Barry E. Stein
Abstract There is now a good deal of data from neurophysiological studies in animals and behavioral studies in human infants regarding the development of multisensory processing capabilities. Although the conclusions drawn from these different datasets sometimes appear to conflict, many of the differences are due to the use of different terms to mean the same thing and, more problematic, the use of similar terms to mean different things. Semantic issues are pervasive in the field and complicate communication among groups using different methods to study similar issues. Achieving clarity of communication among different investigative groups is essential for each to make full use of the findings of others, and an important step in this direction is to identify areas of semantic confusion. In this way investigators can be encouraged to use terms whose meaning and underlying assumptions are unambiguous because they are commonly accepted. Although this issue is of obvious importance to the large and very rapidly growing number of researchers working on multisensory processes, it is perhaps even more important to the non-cognoscenti. Those who wish to benefit from the scholarship in this field but are unfamiliar with the issues identified here are most likely to be confused by semantic inconsistencies. The current discussion attempts to document some of the more problematic of these, begin a discussion about the nature of the confusion and suggest some possible solutions. [source]

Debating the greening vs. browning of the North American boreal forest: differences between satellite datasets

Abstract A number of remote sensing studies have evaluated the temporal trends of the normalized difference vegetation index (NDVI or vegetation greenness) in the North American boreal forest during the last two decades, often getting quite different results. To examine the effect that the use of different datasets might be having on the estimated trends, we compared the temporal trends of recently burned and unburned sites of boreal forest in central Canada calculated from two datasets: the Global Inventory, Monitoring, and Modeling Studies (GIMMS), which is the most commonly used 8 km dataset, and a new 1 km dataset developed by the Canadian Centre for Remote Sensing (CCRS). We compared the NDVI trends of both datasets along a fire severity gradient in order to evaluate the variance in regeneration rates. Temporal trends were calculated using the seasonal Mann,Kendall trend test, a rank-based, nonparametric test, which is robust against seasonality, nonnormality, heteroscedasticity, missing values, and serial dependence. The results showed contrasting NDVI trends between the CCRS and the GIMMS datasets. The CCRS dataset showed NDVI increases in all recently burned sites and in 50% of the unburned sites. Surprisingly, the GIMMS dataset did not capture the NDVI recovery in most burned sites and even showed NDVI declines in some burned sites one decade after fire. Between 50% and 75% of GIMMS pixels showed NDVI decreases in the unburned forest compared with <1% of CCRS pixels. Being the most broadly used dataset for monitoring ecosystem and carbon balance changes, the bias towards negative trends in the GIMMS dataset in the North American boreal forest has broad implications for the evaluation of vegetation and carbon dynamics in this region and globally. [source]

Global change and carnivore body size: data are stasis

GLOBAL ECOLOGY, Issue 2 2009
Shai Meiri
ABSTRACT Aim, Global warming and other anthropogenic changes to the environment affect many aspects of biology and have often been invoked as causing body size changes in vertebrates. Here we examine a diverse set of carnivore populations in search of patterns in body size change that could reflect global warming (in accord with Bergmann's rule). Location, Global. Methods, We used > 4400 specimens representing 22 carnivore species in 52 populations collected over the last few decades to examine whether size changed with collection date when geography and sex are accounted for. We then examined several factors related to global warming, body mass, diet, and the attributes of the different datasets, to see whether they affect the standardized slope (,) of the size versus time regression. Results, Six of 52 populations we examined show a significant effect of year of collection on body size at the 0.05 probability level. The response of size to global warming does not reflect spatial patterns of size variation, nor do diet or body mass affect tendency of populations to change in body size. Size changes are no more pronounced in populations that have been sampled more recently. However, change, where it occurs, is rapid. Main conclusions, There may be a tendency in the literature to report only cases where recent changes are prevalent. Although in our data only a minority of populations show body size changes, we may see changes accelerating in the future in response to more drastic climatic changes and other anthropogenic changes. [source]

Partial least squares path modelling for relations between baseline factors and treatment outcomes in periodontal regeneration

Yu-Kang Tu
Abstract Background: Some clinical outcome variables in periodontal research are mathematically coupled, and it is not feasible to include all the mathematically coupled variables in an ordinary least squares (OLS) regression analysis. The simplest solution to this problem is to drop at least one of the mathematically coupled variables. However, this solution is not satisfactory when the mathematically coupled variables have distinctive clinical implications. Material and Methods: Partial least squares (PLS) methods were used to analyse data from a study on guided tissue regeneration. Relationships between characteristics of baseline lesions and treatment outcomes after 1 year were analysed using PLS, and the results were compared with those from OLS regression. Results: PLS analysis suggested that there were multiple dimensions in the characteristics of baseline lesion: vertical dimension was positively associated with probing pocket depth (PPD) reduction and clinical attachment level (CAL) gain, whilst horizontal dimension was negatively associated with the outcome. Baseline gingival recession had a negative association with PPD reduction but a small positive one with CAL gain. Conclusion: PLS analysis provides new insights into the relationships between baseline characteristics of infrabony defects and periodontal treatment outcomes. The hypothesis of multiple dimensions in baseline lesions needs to be validated by further analysis of different datasets. [source]

Combining inflation density forecasts

Christian Kascha
Abstract In this paper, we empirically evaluate competing approaches for combining inflation density forecasts in terms of Kullback,Leibler divergence. In particular, we apply a similar suite of models to four different datasets and aim at identifying combination methods that perform well throughout different series and variations of the model suite. We pool individual densities using linear and logarithmic combination methods. The suite consists of linear forecasting models with moving estimation windows to account for structural change. We find that combining densities is a much better strategy than selecting a particular model ex ante. While combinations do not always perform better than the best individual model, combinations always yield accurate forecasts and, as we show analytically, provide insurance against selecting inappropriate models. Logarithmic combinations can be advantageous, in particular if symmetric densities are preferred. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Taxonomic sufficiency in two case studies: where does it work better?

Tiziano Bacci
Abstract In marine macrobenthos studies the identification of organisms at species level is the best entry to ecological and biological information about the animals. An accurate identification requires excellent conservation of the organisms, reliable fauna description, experts and lengthy work in the laboratory. The aim of this work is to test taxonomic sufficiency (TS) in two deliberately selected different case studies to understand whether and how the taxonomic complexity of a benthic assemblage influences the results of TS and where it works better. The first benthic settlement was collected in an area characterized by homogeneous depth and grain size composition (case study A) around an off-shore gas platform, while the second one was collected along a coast-wide transect in an area with human pressure limited to fishing activities (case study B). Univariate and multivariate statistical analysis was used to assess differences in the taxonomic structure of benthic assemblages and to test TS on the two different datasets. TS seems to work in both sites, from species to higher taxonomic levels, and the family taxonomic level appears the best compromise for taxonomic resolution when an accurate identification is not achievable. The application of TS does not indicate a significant difference between the two datasets and appears therefore to be a valid instrument to analyse and describe the structure of benthic settlements in the case of taxonomically complex communities. [source]

Latest news and product developments

PRESCRIBER, Issue 20 2007
Article first published online: 26 NOV 200
GPs and pharmacists to work more closely Closer working between GPs and community and primary-care pharmacists ,could further improve prescribing quality and therapeutic outcomes for patients', according to a report by the London School of Pharmacy and Alliance Boots. The report suggests that the expansion of primary-care centres and the increasing complexity of care they offer mean that community pharmacists will increasingly need to take on some GP roles. It foresees an increase in shared premises and calls for closer interdisciplinary working between GPs, pharmacists and nurses. Variation in PCT commissioning of enhanced services from pharmacies has resulted in ,a fragmented system of postcode pharmaceutical care rationing'. Full read-write access to patients' records will be essential if the benefits of electronic prescribing are to be realised. How pharmacists can support commissioners The NHS Alliance and Primary Care Pharmacists' Association have published a guide for practice-based commissioners on making the most of primary-care pharmacists. Prescribing Support and Prescribing Advice for Practice Based Commissioners , A Guide for Commissioning Groups and GPs illustrates how pharmacists can support commissioners at all levels of medicines use. Copies are free to NHS Alliance members and cost £10 for others. Directory website aids diabetes management The National Diabetes Support Team is developing a website that brings together different datasets and tools for diabetes management. The Diabetes Data Directory (www.yhpho.org.uk/diabetesdatadirectory/introddd.asp) summarises what other online databases can provide and lists the tools that can be used to answer specific questions. The first edition is now online, providing direct links to the appropriate sites. Flu vaccine efficacy in older people challenged US reviewers have questioned the effectiveness of flu vaccine in older people (Lancet Infect Dis online: 24 September; doi: 10.1016/ S1473-3099(07)70236-0). They were unable to confirm a reduction in flu mortality since 1980, concluding that biased patient selection and nonspecific end-points such as all-cause mortality may have exaggerated the benefits of vaccination in clinical trials. The Department of Health is encouraging younger people in at-risk groups to be vaccinated against flu this winter; last year, 58 per cent of under-65s at risk were not vaccinated. OC cervical cancer risk probably overestimated Recent evidence that oral contraceptives may be associated with a small increase in the incidence of cervical cancer probably overestimates the risk, says the Clinical Effectiveness Unit of the Faculty of Family Planning and Reproductive Health Care (www.ffprhc.org.uk). A recent study in the BMJ reported a 12 per cent reduced overall risk of cancer associated with oral contraceptives but an increased risk of cervical cancer of 38 per 100 000 woman-years after at least eight years' use. The FFPRHC says this study was conducted before the UK cervical screening programme was established, and at a time when the average Inhaled insulin ,unlikely to be cost effective' Inhaled insulin (Exubera) is safe and effective but costs so much more than injected insulin that it is unlikely to be cost effective, according to a new Health Technology Assessment (2007;11:No.33.www.hta.nhsweb.nhs.uk). The review included nine trials (seven of Exubera), in which the only significant difference between inhaled and injected soluble insulin was in patient preference. However, most of the trials used syringes for insulin injection rather than pens. The extra cost of inhaled insulin is put at between £600 and £1000 per year. New topics for NICE The Secretary of State for Health has referred the novel antihypertensive aliskiren (Rasilez) for appraisal by NICE; aliskiren is the first direct renin inhibitor to be introduced. Other referrals to NICE include five clinical guidelines (multiple pregnancy, transient loss of consciousness, lower UTI in men, post-ITU rehabilitation and colorectal and anal cancer). Topics for technology appraisals include cetuximab (Erbitux) for colorectal and head and neck cancers. QOF statistics for 06/07 GPs in England averaged 96.3 per cent of the maximum points available for the clinical domain of the Quality and Outcomes Framework in 2006/07 compared with 97.1 per cent previously, official statistics show. Mean practice scores for most clinical areas were in the mid-90 per cent range, but highest for obesity (100 per cent) and lowest for depression (81 per cent), palliative care (90 per cent), mental health and epilepsy (<95 per cent). NICE consulting on type 2 diabetes guideline NICE is consulting on its draft clinical guideline for the management of type 2 diabetes. Comments should be submitted online by 22 November; publication is scheduled for April 2008. The drug of first choice for glycaemic control is metformin, which should be considered even for patients who are not overweight; a sulphonylurea is an alternative or adjunctive agent if glycaemic control is not achieved with metformin alone. If these regimens fail, a glitazone may be added. Exenatide (Byetta) is recommended only for obese patients for whom other oral treatments have failed. The guidance will update and replace clinical guidelines E, F, G and H, and technology appraisals 53, 60 and 63. Glitazones increase risk of HF but not CV death A new meta-analysis , this time of seven trials involving a total of 20 191 patients with type 2 diabetes or impaired glucose tolerance treated with a glitazone , has concluded that these agents are associated with an increased risk of heart failure but not cardiovascular death (Lancet 2007;370:1129,36). Compared with comparator drugs, glitazones were associated with an increased risk of congestive heart failure (2.3 vs 1.4 per cent; relative risk, RR, 1.72; number needed to harm over 30 months, 107). There was no heterogeneity between studies, showing that this is a class effect. However, the risk of cardiovascular death was not increased for either rosiglitazone (Avandia) or pioglitazone (Actos). Copyright © 2007 Wiley Interface Ltd [source]

Comparing mass-consistent atmospheric moisture budgets on an irregular grid: An Arctic example

M. Göber
Abstract We present a method to minimize the effects of different resolution and mass imbalance when comparing atmospheric energy and water budgets from different datasets. Sizeable differences between re-analysis- and radiosonde-based atmospheric budgets had been found in earlier studies and it had been suspected that the different resolutions of the datasets strongly contributes to these discrepancies. Furthermore, most studies so far had used mass-imbalanced wind fields, which can lead to serious errors. We balance the wind field by using a variational modification algorithm combined with a finite-element discretization which allows the use of data on a grid defined by the radiosonde network. This method permits the computation of flux divergences in integral form and gives a consistent numerical method to get a mass-balanced wind field with minimum modifications. Applying this method to Arctic radiosonde and re-analysis data on the same grid leads to a better agreement with respect to the horizontal distribution and the mean annual cycle of the moisture flux convergence. The constraint of mass balance on the wind field leads to a greatly reduced and more realistic variability in space and time. However, a systematic difference of about 20% remains between the estimate based on a re-analysis dataset sampled only on the coarse grid of the radiosonde network and an estimate based on the use of the full, fine grid of the re-analysis. These systematic differences can be significantly reduced by creating a simulated radiosonde dataset from the re-analysis with doubled resolution. We undertake an extensive analysis of the uncertainty of the estimates originating from the choices made in the specification of the algorithm. Based solely on radiosonde data, which are likely to result in a low bias, we estimate the net water gain of the Arctic atmosphere as 164 ± 10 mm yr,1 (0.45 ± 0.03 mm d,1) for 1979,93. Copyright © 2003 Royal Meteorological Society. [source]

The role of integrated geophysical survey methods in the assessment of archaeological landscapes: the case of Portus

Simon Keay
Abstract The regular application of geophysical, geochemical and topographical survey techniques to evaluate archaeological sites is well established as a method for locating, defining and mapping buried archaeological materials. However, it is not always feasible to apply a range of different methods over a particular site or landscape due to constraints in time or funding. This paper addresses the integrated application of a variety of survey techniques over different sites and landscapes in Italy and elsewhere, focusing on the recent results from the ongoing survey and excavations at Portus, the port of Imperial Rome. An integration of methods, including magnetometry, resistance survey, ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) has been used at the site to fulfil a number of different research objectives. Results of the magnetometer survey have successfully recorded the nature and extent of archaeological material over an area of 220,ha, allowing a plan of the port and related structures to be produced and variations in archaeological potential across the entire landscape to be assessed. The integration of several techniques in one area of the site between the Porto di Claudio and the Porto di Traiano has mapped the structural remains of this area of the port prior to and during investigation of the zone through excavation. Current work on the geophysical survey data, using different software programs for the processing of survey data and merging different datasets using geographical information system packages, has allowed the results of the work to be visualized and presented to archaeologists in a comprehensive and unambiguous fashion, facilitating the future management and preservation of the site. In addition ongoing research is using different statistical and visual methods of integration to refine the archaeological interpretation of the study area. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Data linkage using probabilistic decision rules: A primer,

Craig Alan Mason
Abstract Electronic data linkage is increasingly being used by researchers and health professionals in the birth defects field as a tool for enhancing both research and service/care. However, in many cases, a common pre-existing ID number does not exist across different datasets, and common identifiers, such as names or dates of birth, which could be used to match records, may be known to contain errors or even legitimate differences over time. In such situations, probabilistic matching, which does not require that all identifying fields exactly agree in order for one to conclude that two records belong to the same individual, can be a valuable tool for improving data linkage. However, probabilistic matching is computationally complex and demanding, and not well understood by many who may wish to apply it in their work. Therefore, the purpose of this article is to provide an overview of one approach to probabilistic matching, including the step-by-step procedures involved in the calculation of indices corresponding to the likelihood that two records are a correct match. In addition, the use of multiple iterative protocols, in which several different matching strategies are used in order to maximize the number of linked records, is discussed. Finally, issues related to deduplication and verification of internal-consistency in the linked data set are also reviewed. Birth Defects Research (Part A), 2008. © 2008 Wiley-Liss, Inc. [source]


Shady Shehata
Most of text categorization techniques are based on word and/or phrase analysis of the text. Statistical analysis of a term frequency captures the importance of the term within a document only. However, two terms can have the same frequency in there documents, but one term contributes more to the meaning of its sentences than the other term. Thus, the underlying model should identify terms that capture the semantics of text. In this case, the model can capture terms that present the concepts of the sentence, which leads to discovering the topic of the document. A new concept-based model that analyzes terms on the sentence, document, and corpus levels rather than the traditional analysis of document only is introduced. The concept-based model can effectively discriminate between nonimportant terms with respect to sentence semantics and terms which hold the concepts that represent the sentence meaning. A set of experiments using the proposed concept-based model on different datasets in text categorization is conducted in comparison with the traditional models. The results demonstrate the substantial enhancement of the categorization quality using the sentence-based, document-based and corpus-based concept analysis. [source]