bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some problems and solutions in density estimation from bearing tree data: a review and synthesis
Authors: Bouldin Jim 
Published: July 2008

AbstractAim  I detail several problems and solutions related to estimating pre‐settlement forest density from land surveyors’ bearing tree data. The data have a high value, so clarification of existing problems is needed in the development of a better theoretical framework in which to treat them. I focus on absolute density because it is the foundation for several other variables, e.g. basal area, timber volume and carbon content.Location  The issues raised are relevant to the vast area encompassed by rectangular land surveys, including the General Land Office survey area of the United States (roughly, Ohio and Florida to the Pacific coast and Alaska), as well as significant areas in the eastern United States, and possibly elsewhere.Methods  A literature review details the history and nature of density estimation from bearing tree data, and spatial simulations quantify the effects of certain identified problems on density estimates. The review focuses on methodological issues appearing in the ecological and biometrical literature.Results  Problems encountered in the literature and addressed here include: (1) aggregated tree spatial patterns and their effect on density using traditional estimators; (2) the mis‐designation of bearing tree labels in relation to definitions given in the estimators; (3) biases due to small sample size; and (4) surveyor‐induced biases. Simulations of aggregated tree populations having a 44‐fold density variation show that estimates ranging from 5 to 127 per cent of actual can result, depending on the estimator used, the scale at which it is calculated, and the error in tree distance rank assignments. The traditionally used estimator is accurate only when trees are spatially random throughout, and sample size is not small. More robust estimators exist that can accommodate a wider range of variation in spatial pattern, sampling design and sample size. One of these is discussed in detail.Main conclusions  Data users should pay much closer attention to critical aspects of bearing tree data and analytical methods, provide basic but necessary descriptive data, and more accurately represent the inherent range of possible errors of estimate. They can narrow this range of uncertainty by using the methods and considerations discussed here and in other recent work.
Step‐less models for regional environmental variation in Norway
Authors: Bakkestuen Vegar , Erikstad Lars , Halvorsen Rune 
Published: July 2008

AbstractAim  To assess the scale of variation for major environmental gradients in Norway. To obtain a step‐less model for this variation and to use this model to evaluate the extent to which the consensus expert classification of Norway into vegetation regions can be predicted from environmental variables. To discuss the potential of step‐less models for understanding natural variation at regional scales, for stratification and for predictive modelling of species distributions and land‐cover types.Location  The mainland of Norway.Methods  Fifty‐four climatic, topographical, hydrological and geological variables were recorded for grid cells with spatial resolution (grain size) of 1 × 1, 5 × 5 and 10 × 10 km, spanning the entire mainland of Norway. Principal components analyses (PCA) were used to summarize variation in three primary data matrices and three random subsets of these.Results  The first four principal components explained between 75% and 85% of the variation in the data sets. All PCAs revealed four consistent environmental gradients, in order of decreasing importance: (1) regional variation (gradient) from coast to inland and from oceanic/humid to continental areas; (2) regional variation from north to south and from high to low altitudes; (3) regional variation from north to south and from inland to coast, related to solar radiation; and (4) topographic (terrain relief) variation on finer scales than (1–3).The first two PCA axes corresponded to the two bioclimatic gradients used in expert classifications of Norway into biogeographical regions: vegetation sections (from highly oceanic to slightly continental) and vegetation zones (from nemoral to alpine).Main conclusions  Our PCA analyses substantiate the current view of bioclimatic regional vegetation variation in Norway, provide an explicit characterization of this variation in terms of climatic variables, and show that environmental variability can be reproduced as GIS layers in step‐less models. These models have the potential to become important tools for future predictive modelling within resource management, conservation planning and biogeographical (and other ecological) research.
Phylogenetic relationships of assimineid gastropods of the Death Valley–lower Colorado River region: relicts of a late Neogene marine incursion?
Authors: Hershler Robert , Liu Hsiu‐Ping 
Published: July 2008

AbstractAim  A small fauna of amphibious snails (genus Assiminea Fleming, 1828) living in association with highly mineralized springs in the Death Valley–lower Colorado River region (DVLCR) is thought to be a relict of the Bouse Embayment, a putative late Miocene–early Pliocene transgression of the ancestral Gulf of California along the lower Colorado River valley. We analysed the phylogenetic relationships of this fauna using mtDNA sequence data (1171 bp) to determine whether, as would be consistent with this hypothesis, it forms a substantially divergent unit sister to marine coastal congeners.Location  South‐western Great Basin and lower Colorado River region, USA.Methods  Two genes [mitochondrial cytochrome c oxidase subunit I (COI) and the mitochondrial 16S ribosomal RNA gene] were sequenced for 10 populations of DVLCR assimineas (Assiminea infimaBerry, 1947; Assiminea sp.). We also sequenced an undescribed population from a spring in the Colorado River delta; western North American Pacific Coastal Assiminea californica (Tryon, 1865); the three other congeners that live on the continent; and three Old World assimineids (outgroups). Phylogenies based on the combined data set were obtained using Bayesian methods, and divergence times were estimated using a COI molecular clock for related gastropods.Results  Composite haplotypes of the DVLCR assimineas, together with that observed in the Colorado River delta population, formed a weakly supported clade that was sister to a clade composed of populations of North American Pacific and Atlantic coastal species. The genetic distance between members of these two clades was 3.46 ± 0.47% for COI and 1.69 ± 0.38% for 16S. The former clade was composed of five subunits that differed from each other by 1.29–2.84% (COI) and 0.52–1.98% (16S) sequence divergence.Main conclusions  Application of the COI clock suggests that progenitors of the DVLCR fauna diverged from coastal ancestors 2.13–1.89 Ma (late Pliocene), several million years after the Bouse Embayment would have been terminated by the establishment of the lower (freshwater) Colorado River. This finding, together with shallow genetic structuring of several DVLCR lineages that are widely distributed across the topographically complex regional landscape, suggests that the Assiminea fauna of this inland area was more likely to have been founded by coastal colonists transported on water birds than through a direct connection with the sea.
Coralligenous habitat in the northern Adriatic Sea: an overview
Authors: Casellato Sandra , Stefanon Antonio 
Published: July 2008

AbstractThe rocky outcrops irregularly scattered in the sandy‐muddy sea bed of the Northern Adriatic, formed by a base rock and a superimposed concretion of vegetal and animal organisms, are considered an infralittoral coralligenous habitat, according to the most recent definition. In the last four decades, research has mainly concentrated on their geology because of the question of the origin of the base rock – very similar to beachrock – which has only recently been attributed to sedimentary cementation induced by methane seeps. Studies on their macrobenthic assemblages have also been published recently, but true comparisons among them are difficult because they mostly refer only to a few selected phyla or to short‐term observations. Very few papers deal with the whole of the animal and plant communities, including all taxonomic groups and the most important environmental variables. On the basis of the literature data concerning several outcrops in the Gulf of Venice, we suggest that the Adriatic reefs differ slightly from the classic deeper coralligenous assemblages around the Mediterranean coast because they have smaller concretions of algae builders. We also suggest that the Northern Adriatic coralligenous reefs are younger than the other reefs occurring in the Mediterranean Sea.
Plasma volume replacement with HES 130/0.42 obviates negative side effects of pneumoperitoneum in piglets
Authors: OSTHAUS WILHELM ALEXANDER , HUBER DIRK , BÄUMKER CHRISTOPH , WITT LARS , METZELDER MARTIN , KUEBLER JOCHEN , SÜMPELMANN ROBERT 
Published: July 2008

SummaryBackground:  Evidence‐based guidelines on optimal perioperative fluid management in infants have not been established. Recent randomized trials in major abdominal surgery in adults suggest that large volumes of fluid may increase morbidity and hospital stay. Our own clinical experience in infants undergoing laparoscopic surgery is different. So the aim of this study was to compare a crystalloid vs a plasma volume stabilizing fluid management regime during prolonged pneumoperitoneum (PP) in an experimental setting.Methods:  Fifteen German landrace piglets were randomized to one of the following treatment groups: control (no PP, 5 ml·kg−1·h−1 electrolyte solution); crystalloid (180 min of PP, 5 ml·kg−1·h−1 electrolyte solution); colloid (180 min of PP, single bolus of 5 ml·kg−1 followed by 5 ml·kg−1·h−1 hydroxyethyl starch 130/0.42/6:2). After decompression, monitoring was continued for a further 120 min. During the investigation, the hemodynamic situation including transpulmonary thermodilution and blood gases was monitored periodically.Results:  During the study, mean arterial pressure remained within the normal range in colloid‐treated animals and controls, but was significantly lower in crystalloid‐treated animals after decompression of PP. Cardiac output remained within the normal range in the colloid and control groups, but decreased in the crystalloid‐treated animals. In the crystalloid group, the lactate concentrations were higher and base excess was lower than in the colloid and control groups at 240 and 300 min (study end).Conclusion:  This study shows that the negative effects of prolonged PP on hemodynamics and acid–base balance can be obviated by a liberal plasma volume stabilization regimen with colloids.
An audit of intravenous fluid prescribing and plasma electrolyte monitoring; a comparison with guidelines from the National Patient Safety Agency
Authors: SNAITH ROSIE , PEUTRELL JANE , ELLIS DAVID 
Published: July 2008

SummaryObjectives:  To audit past practice of intravenous (i.v.) fluid prescribing and electrolyte monitoring, prior to the publication of guidelines by the National Patient Safety Agency (NPSA, Ref. NPSA/2007/22) in March 2007, highlighting areas of discrepancy, in a specialist children’s hospital.Methods:  We performed a retrospective case note review of 100 appendectomy patients between February 2004 and March 2007, recording; fluid type and volumes given as maintenance therapy, resuscitation boluses and nasogastric replacement; the frequency and timing of plasma electrolyte measurement; the relationship between plasma sodium [Na] concentration and i.v. fluid prescribed; and patient weight recordings.Results:  Ninety‐eight acute appendectomies and two interval elective appendectomies. Median age 10 years (interquartile range: 8–11.25). Before surgery, hypotonic maintenance fluid was prescribed for 94% patients. During surgery, maintenance fluid was predominantly isotonic. After surgery, hypotonic maintenance fluid was prescribed for 92% patients. All maintenance fluid volumes were appropriately calculated according to weight using the Holliday and Segar formula (Paediatrics, 19, 1957, 823). Fluid boluses were isotonic on 128/129 occasions and all accurately calculated according to weight. Nasogastric losses were replaced with 0.9% sodium chloride. No patient had daily plasma electrolyte measurements whilst administered i.v. fluid. Twenty‐seven patients had recorded hyponatremia ([Na] <135 mmol·l−1; 21 at presentation, six subsequently after admission). Hypotonic maintenance fluid was continued in 26/27 patients with hyponatremia. No patient had daily weight recorded.Conclusions:  Our practice of i.v. fluid prescribing and electrolyte monitoring in children, prior to the publication of guidelines by the NPSA in March 2007, did not fully meet the recommended standards.
A cohort evaluation of the pediatric ProSeal laryngeal mask airway in 100 children
Authors: KELLY FIONA , SALE STEVEN , BAYLEY GUY , COOK TIM , STODDART PETER , WHITE MICHELLE 
Published: July 2008

SummaryBackground:  The ProSeal® laryngeal mask airway (PLMA) has been available in pediatric sizes in the UK since 2007. Although several non‐UK studies have evaluated PLMAs in children, there are little published data regarding their use in this country. Having decided to introduce the pediatric PLMA into our practice, we chose to prospectively audit the first 100 uses as part of our clinical governance.Methods:  We studied children undergoing elective surgery who were considered suitable for a supraglottic airway. We recorded patient, surgical and insertion details, device performance data and complications. Patient management was not altered by inclusion in this audit.Results:  Twenty size 1.5, 55 size 2.0, 15 size 2.5 and 10 size 3.0 PLMAs were inserted in 100 consecutive children [median age 2 years (range 2 months to 10 years) and median weight 15 kg (range 4.9–60 kg)]. The overall first attempt success rate was 93% (size 1.5, 100%; size 2.0, 100%; size 2.5, 87%; size 3.0, 90%) and overall successful insertion rate was 99%. Median leak pressure was 25 cmH2O. Outright failure was seen in one patient; complications were seen in another six patients (partial airway obstruction in five patients and mild laryngospasm in one patient), all of whom were transient and none of whom required intubation. No episodes of regurgitation were recorded.Conclusions:  Even without prior experience and using nonconventional insertion, pediatric PLMAs (including size 1.5) can be easily inserted and provide an effective airway.
Do School Subsidies Promote Human Capital Investment among the Poor?*
Authors: Martinelli César , Parker Susan W. 
Published: July 2008

AbstractWe investigate the hypothesis that conditioning transfers to poor families on school attendance leads to a reallocation of household resources which enhances the human capital of the next generation, via the effect of the conditionality on the shadow price of human capital and (possibly) via the effect of the transfers on household bargaining. We introduce a model to study the effects of conditional transfers on intra‐household allocations, and provide suggestive evidence of the importance of price effects using data from a conditional transfer program in Mexico.
Interest Rate Risk Rewards in Stock Returns of Financial Corporations: Evidence from Germany
Authors: Czaja Marc‐Gregor , Scholz Hendrik , Wilkens Marco 
Published: July 2008

Abstract The interest rate sensitivity of stock returns of financial and non‐financial corporations is a well‐known phenomenon. However, only little is known about the part of total stock returns that is attributable to the compensation an investor receives for being exposed to interest rate risk when investing in equity securities. We pursue here a benchmark portfolio approach, constructing benchmark portfolios having the same interest rate risk exposure as a particular stock. By studying the time series of returns of these asset‐specific benchmarks, we find: i) Regardless of the industry considered, the interest rate risk benchmarks of German corporations have mostly earned a significantly positive reward. ii) Returns of interest rate risk benchmarks of financial institutions exceeded significantly those of non‐financial corporations. iii) An investor willing to bear nothing but the average interest rate risk of German financial institutions would have earned a mean return of about or even exceeding 70% of the corresponding total stock returns. iv) Returns of the interest rate risk benchmarks of the German insurance sector were significantly higher than those of German banks, which seems to contradict conventional market wisdom that insurances hedge interest rate risks.
Habitat suitability model for Polish wolves based on long‐term national census
Authors: Jędrzejewski W. , Jędrzejewska B. , Zawadzka B. , Borowik T. , Nowak S. , Mysłajek R. W. 
Published: July 2008

AbstractThe central‐European population of wolves Canis lupus has its western border of contiguous range in eastern Poland. Protected since 1998, Polish wolves began to expand towards the west. Based on large‐scale data on wolf abundance (2000–2006) and geographic information system (GIS) tools, we built a habitat suitability model (HSM) for the species in Poland. The best model, selected by the Akaike information criterion, of the resource selection function (RSF) by wolves included percentage cover of forests, meadows and marshes (positively correlated to wolf abundance) and road density (negatively correlated), and explained 53% of the total variation in the wolf abundance index in a 10 × 10 km cell grid. That RSF was then used to evaluate the whole country in terms of suitability for wolves. Potential wolf range appeared to consist of 24 patches of good habitat (predicted relative probability of wolf occurrence ≥30%), including six patches already occupied and 17 new ones. In total, habitat suitable for wolves covers at least 20–24% of Poland, compared with 16% of the country's area now occupied by the species. HSM was validated with historical data on wolf occurrence in 1950–2006. The areas selected by our model and those inhabited by wolves in at least one decade overlapped in 81–86%. Furthermore, the probability of wolf occurrence predicted by the model correlated positively with the number of decades the wolves were actually recorded in the area. Based on the empirical relationship between patch size and wolf numbers, we estimated that Poland could support a population of 1450–1540 wolves, two to three times larger than the current estimate. HSM needs to be supplemented with a GIS‐based connectivity analysis among patches, which in turn should be validated by molecular genetics studies on dispersing wolves. Because of broadly similar geographic conditions, the model may be applicable to eastern Germany, Belarus Republic and the Baltic States (Lithuania, Latvia, Estonia).
Assessing the impact of climate variation on survival in vertebrate populations
Authors: Grosbois V. , Gimenez O. , Gaillard J.‐M. , Pradel R. , Barbraud C. , Clobert J. , Møller A. P. , Weimerskirch H. 
Published: July 2008

AbstractThe impact of the ongoing rapid climate change on natural systems is a major issue for human societies. An important challenge for ecologists is to identify the climatic factors that drive temporal variation in demographic parameters, and, ultimately, the dynamics of natural populations. The analysis of long‐term monitoring data at the individual scale is often the only available approach to estimate reliably demographic parameters of vertebrate populations. We review statistical procedures used in these analyses to study links between climatic factors and survival variation in vertebrate populations.We evaluated the efficiency of various statistical procedures from an analysis of survival in a population of white stork,Ciconia ciconia, a simulation study and a critical review of 78 papers published in the ecological literature. We identified six potential methodological problems: (i) the use of statistical models that are not well‐suited to the analysis of long‐term monitoring data collected at the individual scale; (ii) low ratios of number of statistical units to number of candidate climatic covariates; (iii) collinearity among candidate climatic covariates; (iv) the use of statistics, to assess statistical support for climatic covariates effects, that deal poorly with unexplained variation in survival; (v) spurious detection of effects due to the co‐occurrence of trends in survival and the climatic covariate time series; and (vi) assessment of the magnitude of climatic effects on survival using measures that cannot be compared across case studies. The critical review of the ecological literature revealed that five of these six methodological problems were often poorly tackled. As a consequence we concluded that many of these studies generated hypotheses but only few provided solid evidence for impacts of climatic factors on survival or reliable measures of the magnitude of such impacts.We provide practical advice to solve efficiently most of the methodological problems identified. The only frequent issue that still lacks a straightforward solution was the low ratio of the number of statistical units to the number of candidate climatic covariates. In the perspective of increasing this ratio and therefore of producing more robust analyses of the links between climate and demography, we suggest leads to improve the procedures for designing field protocols and selecting a set of candidate climatic covariates. Finally, we present recent statistical methods with potential interest for assessing the impact of climatic factors on demographic parameters.
Role of KATP Channels in Cephalic Vasodilatation Induced by Calcitonin Gene‐Related Peptide, Nitric Oxide, and Transcranial Electrical Stimulation in the Rat
Authors: Gozalov Aydin , Jansen‐Olesen Inger , Klaerke Dan , Olesen Jes 
Published: July 2008

Objective.— The objective of this study was to explore the role of KATP channels in vasodilatation induced by calcitonin gene‐related peptide (CGRP), nitric oxide (NO), and transcranial electrical stimulation (TES) in intracranial arteries of rat.Background.— Dilatation of cerebral and dural arteries causes a throbbing, migraine‐like pain. Both CGRP and NO are potent vasodilators that can induce migraine. Their antagonists are effective in the treatment of migraine attacks. KATP channel openers cause headache in the majority of healthy subjects suggesting a role for KATP channels in migraine pathogenesis. We hypothesized that vasodilatation induced by CGRP and the NO donor glyceryltrinitrate (GTN) is mediated via KATP channels.Methods.— We examined the effects of the KATP channel inhibitor glibenclamide on dural and pial vasodilatation induced by CGRP, NO, and endogenously released CGRP by TES. A rat genuine closed cranial window model was used for in vivo studies and myograph baths for studying the effect in vitro. In the closed cranial window model the diameter of dural vessels was measured directly in anesthetized animals to investigate the vascular effects of infused CGRP, NO, and endogenous CGRP after electrical stimulation. Also diameter changes of pial arteries, mean arterial blood pressure and local cerebral blood flow by Laser Doppler flowmetry (LCBFFlux) were measured.Results.— CGRP, NO, and TES caused dilatation of the 2 arteries in vivo and in vitro. In anesthetized rats glibenclamide significantly attenuated CGRP induced dural and TES induced dural/pial artery dilatation (P = .001; P = .001; P = .005), but had no effect on dural/pial vasodilatation induced by GTN. In vitro glibenclamide failed to significantly inhibit CGRP‐ and GTN‐induced vasodilatation.Conclusions.— These results show that a KATP channel blocker in vivo but not in vitro inhibits CGRP, but not GTN‐induced dilatation of dural and pial arteries, a mechanism thought to be important in migraine.