bluuebunny/crossref_metadata_2025_split huggingface dataset:
Does conservation planning matter in a dynamic and uncertain world?
Authors: Meir Eli , Andelman Sandy , Possingham Hugh P. 
Published: July 2004

AbstractLoss of biodiversity is one of the world's overriding environmental challenges. Reducing those losses by creating reserve networks is a cornerstone of global conservation and resource management. Historically, assembly of reserve networks has beenad hoc, but recently the focus has shifted to identifying optimal reserve networks. We show that while comprehensive reserve network design is best when the entire network can be implemented immediately, when conservation investments must be staged over years, such solutions actually may be sub‐optimal in the context of biodiversity loss and uncertainty. Simple decision rules, such as protecting the available site with the highest irreplaceability or with the highest species richness, may be more effective when implementation occurs over many years.
Minimizing the cost of environmental management decisions by optimizing statistical thresholds
Authors: Field Scott A. , Tyre Andrew J. , Jonzén Niclas , Rhodes Jonathan R. , Possingham Hugh P. 
Published: July 2004

AbstractEnvironmental management decisions are prone to expensive mistakes if they are triggered by hypothesis tests using the conventional Type I error rate (α) of 0.05. We derive optimal α‐levels for decision‐making by minimizing a cost function that specifies the overall cost of monitoring and management. When managing an economically valuable koala population, it shows that a decision based on α = 0.05 carries an expected cost over $5 million greater than the optimal decision. For a species of such value, there is never any benefit in guarding against the spurious detection of declines and therefore management should proceed directly to recovery action. This result holds in most circumstances where the species’ value substantially exceeds its recovery costs. For species of lower economic value, we show that the conventional α‐level of 0.05 rarely approximates the optimal decision‐making threshold. This analysis supports calls for reversing the statistical ‘burden of proof’ in environmental decision‐making when the cost of Type II errors is relatively high.
Diversity and composition of tropical soil nitrifiers across a plant diversity gradient and among land‐use types
Authors: Carney Karen M. , Matson Pamela A. , Bohannan Brendan J. M. 
Published: July 2004

AbstractAmmonia‐oxidizing bacteria (AOB) perform the rate‐limiting step of nitrification, a key ecosystem process that in part determines the fate of nitrogen in ecosystems. However, little is known about the factors that determine soil AOB diversity or composition, especially in tropical systems. Using a set of study systems in Costa Rica, we examined whether plant diversity or land‐use influenced AOB diversity or composition and whether AOB diversity or composition were associated with nitrification rates. We characterized the molecular diversity and composition of AOB via polymerase chain reaction amplification, cloning, and sequencing of 16S rDNA. We found that AOB diversity or composition did not change significantly across plant diversity treatments. In contrast, AOB differed among land‐use types in some measures of diversity and in composition, and differences in AOB composition among land‐use types were correlated with potential rates of nitrification. Our results suggest that anthropogenic changes of ecosystems can alter microbial communities in ways that may affect the processes they mediate.
Species–energy relationships and habitat complexity in bird communities
Authors: Hurlbert Allen H. 
Published: July 2004

AbstractSpecies–energy theory is a commonly invoked theory predicting a positive relationship between species richness and available energy. The More Individuals Hypothesis (MIH) attempts to explain this pattern, and assumes that areas with greater food resources support more individuals, and that communities with more individuals include more species. Using a large dataset for North American birds, I tested these predictions of the MIH, and also examined the effect of habitat complexity on community structure. I found qualitative support for the relationships predicted by the MIH, however, the MIH alone was inadequate for fully explaining richness patterns. Communities in more productive sites had more individuals, but they also had more even relative abundance distributions such that a given number of individuals yielded a greater number of species. Richness and evenness were also higher in structurally complex forests compared to structurally more simple grasslands when controlling for available energy.
Effect of trap design, trap size and pheromone dose on male capture of two pine bast scales species (Hemiptera: Matsucoccidae): implications for monitoring and mass‐trapping
Authors: Branco M. , Jactel H. , Silva E. B. , Binazzi A. , Mendel Z. 
Published: July 2004

Abstract 1 The effects of pheromone dose, trap size and trap design on the capture of maleMatsucoccus feytaudiwere studied in maritime pine forests of Portugal, France and Italy, andMatsucoccus josephiin Aleppo pine stands of Israel.2 Males of both species respond to racemic mixtures of the respective sex pheromone at a dosage as low as 25 µg. However, for low population densities ofM. feytaudi, a 50 µg dosage was needed to guarantee male catches significantly different from the control trap.3 Male capture increased with increasing dosage up to a threshold level for both species. Overdose repellence was not observed even with baits containing 1600 and 2200 µg of the pheromone ofM. josephiandM. feytaudi, respectively.4 ForM. feytaudi, a higher dose–response was observed at medium population densities, whereas lesser captures were registered at low and high population densities, suggesting female competition in the latter case.5 Catches ofM. feytaudimales were not affected by trap design, whereasM. josephimales were caught in significantly greater numbers in delta traps. Large traps caught significantly more males of both species.6 The relative higher male catches in the marginal zone of the sticky traps is probably related to males landing behaviour in the vicinity of the pheromone source.7 The shape and size of the trap did not affect the bias of the estimates of male catches. However, the plate traps provided higher precision. Both bias and precision improved with increasing dose.
Interactions between the stem‐mining weevils Ceutorhynchus napi Gyll. and Ceutorhynchus pallidactylus (Marsh.) (Coleoptera: Curculionidae) in oilseed rape
Authors: Dechert Georg , Ulber Bernd 
Published: July 2004

Abstract  1 The rape stem weevil Ceutorhynchus napi Gyll. and the cabbage stem weevil Ceutorhynchus pallidactylus (Marsh.) share the same habitat and food resource within the stems of oilseed rape, Brassica napus L. var. oleifera. Interactions occurring between these two sympatric species on this host were studied under both field and laboratory conditions.2 The oviposition preference of C. pallidactylus and the within‐plant distribution of eggs and larvae were examined in field plots of oilseed rape. Female C. pallidactylus tended to lay their eggs in plants already infested by eggs and larvae of C. napi rather than in uninfested plants. The within‐plant distribution of the egg batches of C. pallidactylus did not differ significantly between uninfested plants and those preinfested by C. napi. Ovipositing females of C. napi and C. pallidactylus generally showed a significant preference for plants with larger stem diameter.3 Laboratory choice tests provided further evidence for the oviposition preference of C. pallidactylus. Females laid significantly more eggs in leaves of plants that had been previously infested by C. napi than in leaves of previously uninfested plants.4 Larvae of C. pallidactylus showed a significant shift of their feeding niche towards the stem base when feeding in individual plants attacked by both species. This possibly indicates ressource partitioning between C. pallidactylus and C. napi. The within‐plant distribution of C. napi larvae was not affected by the simultaneous attack of C. pallidactylus.5 The size of the head capsule of full‐grown larvae of C. napi and C. pallidactylus was not significantly correlated with the diameter of the stem of their host plant or with the number of conspecific larvae within individual plants.
Oral toxicity and impact on fecundity of three insecticidal proteins on the gregarious ectoparasitoid Eulophus pennicornis (Hymenoptera: Eulophidae)
Authors: Bell H. A. , Kirkbride‐Smith A. E. , Marris G. C. , Edwards J. P. , Gatehouse A. M. R. 
Published: July 2004

Abstract  1 The effects of three insecticidal transgene proteins on selected life parameters of the ectoparasitoid Eulophus pennicornis were investigated.2 When incorporated into the diet of the adult wasp, the lectins GNA (snowdrop lectin) and Con A (jackbean lectin) significantly reduced longevity at doses of 0.1% w/v and above. At a dose rate of 0.1% w/v, GNA and Con A reduced mean longevity to approximately 13 and 10 days, respectively, compared with average control lifespans of approximately 20 days. The trypsin inhibitor from cowpeas, CpTI, had no marked effect on longevity.3 Both lectins reduced reproductive fitness of parasitoids when dosed before exposure to hosts. The 1.0% dose reduced fecundity by over 35% for GNA and 70% for Con A. Although reduced fecundity may have been a function of shorter lifespans, smaller egg loads in female wasps provided evidence to suggest that higher lectin doses may have interfered with egg maturation processes.4 Both lectins were readily detected in whole body extracts of the parasitoid and were seen to persist within their bodies for at least 24 h after cessation of feeding on lectin‐containing diets.5 The results would indicate that the ingestion of the lectins, either through host feeding or through the consumption of nectar, may pose a hazard to parasitic wasps if present at sufficiently high concentrations.
A Conditional Approach for Multivariate Extreme Values (with Discussion)
Authors: Heffernan Janet E. , Tawn Jonathan A. 
Published: July 2004

SummaryMultivariate extreme value theory and methods concern the characterization, estimation and extrapolation of the joint tail of the distribution of a d-dimensional random variable. Existing approaches are based on limiting arguments in which all components of the variable become large at the same rate. This limit approach is inappropriate when the extreme values of all the variables are unlikely to occur together or when interest is in regions of the support of the joint distribution where only a subset of components is extreme. In practice this restricts existing methods to applications where d is typically 2 or 3. Under an assumption about the asymptotic form of the joint distribution of a d-dimensional random variable conditional on its having an extreme component, we develop an entirely new semiparametric approach which overcomes these existing restrictions and can be applied to problems of any dimension. We demonstrate the performance of our approach and its advantages over existing methods by using theoretical examples and simulation studies. The approach is used to analyse air pollution data and reveals complex extremal dependence behaviour that is consistent with scientific understanding of the process. We find that the dependence structure exhibits marked seasonality, with ex- tremal dependence between some pollutants being significantly greater than the dependence at non-extreme levels.
Markov Chain Monte Carlo Methods for High Dimensional Inversion in Remote Sensing
Authors: Haario H. , Laine M. , Lehtinen M. , Saksman E. , Tamminen J. 
Published: July 2004

SummaryWe discuss the inversion of the gas profiles (ozone, NO3, NO2, aerosols and neutral density) in the upper atmosphere from the spectral occultation measurements. The data are produced by the ‘Global ozone monitoring of occultation of stars’ instrument on board the Envisat satellite that was launched in March 2002. The instrument measures the attenuation of light spectra at various horizontal paths from about 100 km down to 10–20 km. The new feature is that these data allow the inversion of the gas concentration height profiles. A short introduction is given to the present operational data management procedure with examples of the first real data inversion. Several solution options for a more comprehensive statistical inversion are presented. A direct inversion leads to a non-linear model with hundreds of parameters to be estimated. The problem is solved with an adaptive single-step Markov chain Monte Carlo algorithm. Another approach is to divide the problem into several non-linear smaller dimensional problems, to run parallel adaptive Markov chain Monte Carlo chains for them and to solve the gas profiles in repetitive linear steps. The effect of grid size is discussed, and we present how the prior regularization takes the grid size into account in a way that effectively leads to a grid-independent inversion.
Bayesian Analysis of the Scatterometer Wind Retrieval Inverse Problem: Some New Approaches
Authors: Cornford Dan , Csató Lehel , Evans David J. , Opper Manfred 
Published: July 2004

SummaryThe retrieval of wind vectors from satellite scatterometer observations is a non-linear inverse problem. A common approach to solving inverse problems is to adopt a Bayesian framework and to infer the posterior distribution of the parameters of interest given the observations by using a likelihood model relating the observations to the parameters, and a prior distribution over the parameters. We show how Gaussian process priors can be used efficiently with a variety of likelihood models, using local forward (observation) models and direct inverse models for the scatterometer. We present an enhanced Markov chain Monte Carlo method to sample from the resulting multimodal posterior distribution. We go on to show how the computational complexity of the inference can be controlled by using a sparse, sequential Bayes algorithm for estimation with Gaussian processes. This helps to overcome the most serious barrier to the use of probabilistic, Gaussian process methods in remote sensing inverse problems, which is the prohibitively large size of the data sets. We contrast the sampling results with the approximations that are found by using the sparse, sequential Bayes algorithm.
Probabilistic Sensitivity Analysis of Complex Models: A Bayesian Approach
Authors: Oakley Jeremy E. , O'Hagan Anthony 
Published: July 2004

SummaryIn many areas of science and technology, mathematical models are built to simulate complex real world phenomena. Such models are typically implemented in large computer programs and are also very complex, such that the way that the model responds to changes in its inputs is not transparent. Sensitivity analysis is concerned with understanding how changes in the model inputs influence the outputs. This may be motivated simply by a wish to understand the implications of a complex model but often arises because there is uncertainty about the true values of the inputs that should be used for a particular application. A broad range of measures have been advocated in the literature to quantify and describe the sensitivity of a model's output to variation in its inputs. In practice the most commonly used measures are those that are based on formulating uncertainty in the model inputs by a joint probability distribution and then analysing the induced uncertainty in outputs, an approach which is known as probabilistic sensitivity analysis. We present a Bayesian framework which unifies the various tools of prob- abilistic sensitivity analysis. The Bayesian approach is computationally highly efficient. It allows effective sensitivity analysis to be achieved by using far smaller numbers of model runs than standard Monte Carlo methods. Furthermore, all measures of interest may be computed from a single set of runs.
Exact Filtering for Partially Observed Continuous Time Models
Authors: Fearnhead Paul , Meligkotsidou Loukia 
Published: July 2004

SummaryThe forward–backward algorithm is an exact filtering algorithm which can efficiently calculate likelihoods, and which can be used to simulate from posterior distributions. Using a simple result which relates gamma random variables with different rates, we show how the forward–backward algorithm can be used to calculate the distribution of a sum of gamma random variables, and to simulate from their joint distribution given their sum. One application is to calculating the density of the time of a specific event in a Markov process, as this time is the sum of exponentially distributed interevent times. This enables us to apply the forward–backward algorithm to a range of new problems. We demonstrate our method on three problems: calculating likelihoods and simulating allele frequencies under a non-neutral population genetic model, analysing a stochastic epidemic model and simulating speciation times in phylogenetics.
A Nonparametric Test to Compare Survival Distributions with Covariate Adjustment
Authors: Heller Glenn , Venkatraman E. S. 
Published: July 2004

SummaryThe analysis of covariance is a technique that is used to improve the power of a k-sample test by adjusting for concomitant variables. If the end point is the time of survival, and some observations are right censored, the score statistic from the Cox proportional hazards model is the method that is most commonly used to test the equality of conditional hazard functions. In many situations, however, the proportional hazards model assumptions are not satisfied. Specifically, the relative risk function is not time invariant or represented as a log-linear function of the covariates. We propose an asymptotically valid k-sample test statistic to compare conditional hazard functions which does not require the assumption of proportional hazards, a parametric specification of the relative risk function or randomization of group assignment. Simulation results indicate that the performance of this statistic is satisfactory. The methodology is demonstrated on a data set in prostate cancer.
How long should urinary bladder catheterisation be continued after vaginal prolapse surgery?
Authors: Hakvoort R.A. , Elberink R. , Vollebregt A. , Van der Ploeg T. , Emanuel M.H. 
Published: July 2004

Objective  To determine whether prolonged urinary bladder catheterisation after vaginal prolapse surgery is advantageous.Design  Randomised controlled trial.Setting  A large training hospital in the Netherlands.Population  Patients undergoing anterior colporrhaphy.Methods  One hundred patients were included. Patients were randomised into two groups. In one group (n= 50), a transurethral catheter was in place for four days post‐operatively and removed on the fifth post‐operative day. In the other group (n= 50), catheterisation was not prolonged and the catheter was removed the morning after surgery. Residual volumes after removal of the catheter were measured by ultrasound scanning. Where residual volumes of >200 mL were found the patient was recatheterised for three more days. Urinary cultures were taken before removal of the catheter. Six patients were excluded: four in the standard prolonged catheterisation group and two in the not prolonged catheterisation group.Main outcome measures  Need for recatheterisation, urinary tract infection, mean duration of catheterisation and hospital stay.Results  Residual volumes exceeding 200 mL and need for recatheterisation occurred in 9% in the standard prolonged catheterisation group versus 40% of patients in the not prolonged catheterisation group (OR 0.15, 95% CI 0.045–0.47). Positive urine cultures were found in 40% of cases in the standard prolonged catheterisation group compared with 4% in the not prolonged catheterisation group (OR 15, 95% CI 3.2–68.6). Mean duration of catheterisation was 5.3 days in the standard prolonged catheterisation group and 2.3 days in the not prolonged catheterisation group (P < 0.001). Mean duration of hospitalisation was 7 days in the standard prolonged catheterisation group and 5.7 days in the not prolonged group (P < 0.001).Conclusion  The disadvantages of prolonged catheterisation outweigh the advantages, therefore, removal of the catheter on the morning after surgery may be preferable and longer term catheterisation should only be undertaken where there are specific indications.
Thrombophilia and stillbirth: possible connection by intrauterine growth restriction
Authors: Weiner Zeev , Beck‐Fruchter Ronit , Weiss Amir , Hujirat Yasir , Shalev Eliezer , Shalev Stavit A. 
Published: July 2004

Objective  To define the association between thrombophilia and unexplained stillbirth.Design  A case–control study.Setting  Obstetric department in a university affiliated hospital (Ha'Emek Medical Center, Afula).Population  A total of 53 women who delivered stillborns between March 1998 and June 2002 and 59 women with unremarkable obstetric history who delivered at the same period.Methods  Presence of genetic and acquired markers of thrombophilia was investigated.Main outcome measure  Presence or absence of thrombophilia.Results  Thrombophilia was found in 34% of the women who delivered stillborns and in 20% of the 59 women with normal pregnancies (non‐significant). However, significantly higher prevalence of thrombophilia (73%) was found in women who delivered small for gestational age stillborns compared with women who delivered normal birthweight stillborns (73%vs 18.4%, P < 0.0001).Conclusions  There is no association between thrombophilia and stillbirth, overall. However, there is a clear association between thrombophilia and stillbirth of extremely growth restricted infants.
Preterm birth and maternal country of birth in a French district with a multiethnic population
Authors: Zeitlin J. , Bucourt M. , Rivera L. , Topuz B. , Papiernik E. 
Published: July 2004

Objectives  This analysis explores the association between preterm birth and maternal country of birth in a French district with a multiethnic population.Design  Prospective observational study.Setting  District of Seine‐Saint‐Denis in FrancePopulation  48,746 singleton live births from a population‐based birth register between October 1998 and December 2000.Methods  We compare preterm birth rates by mother's country of birth controlling for demograhic and obstetric factors as well as insurance coverage and timing of initiation of antenatal care.Main outcome measures  Overall preterm birth rates and preterm birth rates by timing of delivery (<33 weeks versus 33–36 weeks of gestation), mode of onset (spontaneous or indicated preterm birth) and the presence of hypertension in pregnancy.Results  Women born in Northern Africa, Southern Europe and South/East Asia did not have higher preterm birth rates than women born in continental France. Rates were significantly higher for women born in the overseas French districts in the Caribbean and Indian Ocean and Sub‐Saharan Africa. Excess risk was greatest for early preterm births, medically indicated births and preterm births associated with hypertension.Conclusions  Patterns of preterm birth with relation to timing, mode of onset and medical complications among of Afro‐Caribbean origin should be confirmed in future research.