bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of Psychiatric Comorbidity on the In-Treatment Outcomes of Cocaine-Dependent Patients in Therapeutic Communities
Authors: González-Saiz Francisco , Vergara-Moragues Esperanza , Verdejo-García Antonio , Fernández-Calderón Fermín , Lozano Oscar M. 
Published: June 2013

Background This study aimed to explore the association between psychiatric comorbidity and treatment outcomes in therapeutic communities (TCs). Methods A prospective longitudinal descriptive design was used. A baseline psychopathological assessment was performed within the first 15 to 20 days of treatment in the TCs. The length of treatment stay was computed for each individual. The study was conducted in the region of Andalusia (Spain). The participants were 218 cocaine-dependent individuals. Psychopathological assessment was performed using the Psychiatric Research Interview for Substance and Mental Disorders (PRISM). The outcome measures were retention, defined as the time in TC treatment (number of days), and the patient's assessment upon leaving the TC. Results The number of psychopathological comorbidities present in the last year among the patients was high (57.8%) and was associated with a worse response to treatment ( P =.004). The patients with co-occurring psychiatric disorders had a decreased probability of remaining in the TCs compared with patients who only presented with substance use disorders (hazards ratio = 1.61). Conclusions Psychiatric comorbidity predicts cocaine-dependent individuals’ likelihood of remaining in residential treatment.
Prenatal Methamphetamine Exposure and Neonatal and Infant Neurobehavioral Outcome: Results from the IDEAL Study
Authors: Kiblawi Zeina N. , Smith Lynne M. , Diaz Sabrina D. , LaGasse Linda L. , Derauf Chris , Newman Elana , Shah Rizwan , Arria Amelia , Huestis Marilyn , Haning William , Strauss Arthur , DellaGrotta Sheri , Dansereau Lynne M. , Neal Charles , Lester Barry 
Published: June 2013

Background Methamphetamine (MA) use among pregnant women is an increasing problem in the United States. How MA use during pregnancy affects neonatal and infant neurobehavior is unknown. Methods: The Infant Development, Environment, and Lifestyle (IDEAL) study screened 34,833 subjects at 4 clinical centers. Of the subjects, 17,961 were eligible and 3705 were consented, among which 412 were enrolled for longitudinal follow-up. Exposed subjects were identified by self-report and/or gas chromatography/mass spectroscopy (GC/MS) confirmation of amphetamine and metabolites in meconium. Comparison subjects were matched (race, birth weight, maternal education, insurance), denied amphetamine use, and had a negative meconium screen. Both groups included prenatal alcohol, tobacco, and marijuana use, but excluded use of opiates, lysergic acid diethylamide, or phencyclidine. The Neonatal Intensive Care Unit (NICU) Network Neurobehavioral Scale (NNNS) was administered within the first 5 days of life and again at 1 month to 380 enrollees (185 exposed, 195 comparison). Analysis of variance (ANOVA) tested exposure effects on NNNS summary scores at birth and 1 month. General linear model (GLM) repeated-measures analysis assessed the effect of MA exposure over time on the NNNS scores with and without covariates. Results By 1 month of age, both groups demonstrated higher quality of movement ( P = .029), less lethargy ( P = .001), and fewer asymmetric reflexes ( P = .012), with no significant differences in NNNS scores between the exposed and comparison groups. Over the first month of life, arousal increased in exposed infants but decreased in comparison infants ( P = .031) and total stress was decreased in exposed infants, with no change in comparison infants ( P = .026). Conclusions Improvement in total stress and arousal were observed in MA-exposed newborns by 1 month of age relative to the newborn period.
Dominant bryophyte control over high‐latitude soil temperature fluctuations predicted by heat transfer traits, field moisture regime and laws of thermal insulation
Authors: Soudzilovskaia Nadejda A. , van Bodegom Peter M. , Cornelissen Johannes H.C. 
Published: June 2013

Summary

Bryophytes cover large territories in cold biomes, where they control soil temperature regime, and therefore permafrost, carbon and nutrient dynamics. The mechanisms of this control remain unclear.

We quantified the dependence of soil temperature fluctuations under bryophyte mats on the interplay of bryophyte heat conductance traits, mat thickness, density and moisture regimes.

For seventeen predominant bryophytes in six typical subarctic ecosystems, we assessed in situ soil temperature dynamics under bryophyte mats in comparison with bryophyte‐removal patches and per‐species mat field moisture. In a complimentary laboratory investigation, we studied how per‐species bryophyte thermal conductivity and volumetric heat capacity depend on mat density and moisture content. Subsequently, we tested whether heat transfer through bryophyte mats could be modelled as a function of mat thickness, thermal conductivity and volumetric heat capacity, the latter two being determined by mat density and field moisture content.

Laboratory assessment revealed that bryophyte thermal conductivity and volumetric heat capacity were independent of mat density, and depended linearly on mat moisture content, but the dependencies were not species‐specific. In the field, bryophytes reduced amplitudes of soil temperature fluctuations and freeze–thaw frequency during the growing season, but not mean soil temperature. These effects differed between species and between ecosystems, being strongest in Sphagnum fuscum‐dominated dry tundra, but were well explained by bryophyte mat thickness and field moisture content as affecting thermal conductivity and volumetric heat capacity.

We suggest that reduction in soil temperature amplitudes is a generic feature in (sub) arctic ecosystems and should be considered as an important mechanism of bryophyte control on carbon and nutrient turnover. Although heat transfer through bryophyte mats differs greatly among species and ecosystems, species differences are fully explained by differences in mat thickness and moisture content and generally comply with physical laws, without deviations due to biological processes. These results imply that in global vegetation models of carbon and nutrient cycling, the heat transfer through bryophyte mats can be modelled without taking into consideration bryophyte species composition, but considering bryophyte mat depth and moisture availability only. This will allow us to enhance modelling precision through an improved representation of the soil temperature regime.
The whole‐plant compensation point as a measure of juvenile tree light requirements
Authors: Lusk Christopher H. , Jorgensen Murray. A. 
Published: June 2013

Summary

Although ‘shade tolerance’ has featured prominently in the vocabulary of foresters and ecologists for a century, we have yet to agree on a standardized method for quantifying this elusive property. The ‘whole‐plant compensation point’, interpolated from stem growth measurements across a wide range of light environments, has been proposed as a simple, robust measure of species shade tolerance. Others have argued that shade tolerance is primarily a function of differential ability to survive periods of slow growth (‘suppression’), implying that measurements of survival are vital.

We measured growth of juveniles (500–1000 mm tall) of five evergreen trees over 12 months in a cool‐temperate rain forest in New Zealand, to determine whether whole‐plant compensation points predicted species differences in occupancy of understorey light environments, which were quantified using hemispherical photography.

The five species encompassed 3·5‐fold variation in whole‐plant compensation points. Compensation points of most species fell within the first quartile of the distribution of light environments occupied by juveniles; they were also correlated with low‐light mortality rates of juveniles, estimated from permanent plot data archived in the National Vegetation Survey Databank. Compensation points were also significantly positively correlated with height growth rates in high light, confirming the presence of the growth vs. shade tolerance trade‐off detected in many other forest tree assemblages.

Results show that, in temperate evergreen forests, the whole‐plant compensation point distinguishes reliably between species of differing shade tolerance. Excepting situations involving parameterization of demographic models, shade tolerance can therefore be assessed without survival measurements. However, estimating whole‐plant compensation points may prove more difficult in deciduous forests, where seasonal variation in understorey light transmission poses additional challenges.
Testing the predictions of energy allocation decisions in the evolution of life‐history trade‐offs
Authors: Skibiel Amy L. , Speakman John R. , Hood Wendy R. 
Published: June 2013

Summary

Allocating a greater amount of limited resources, such as energy, to current reproduction can reduce the amount of energy available for somatic maintenance and can ultimately impair future breeding success or maternal survival (i.e. cost of reproduction hypothesis). Although there is some support for the cost of reproduction hypothesis in birds, few empirical studies of mammals have demonstrated a trade‐off between current and future reproduction. More importantly, most studies testing ultimate costs have neglected to confirm that the proximate costs of reproduction are high.

We experimentally manipulated litter size in a wild population of Columbian ground squirrels for 2 years to examine both the proximate energetic and ultimate fitness (i.e. survival and breeding) costs of reproduction. We predicted that females raising augmented litters would have the highest rates of daily energy expenditure and as a result would experience lower survival rates or future fecundity.

Females raising augmented litters weaned more pups, had the highest litter masses at weaning, and had field metabolic rates that were almost 1·5 times greater than females raising control or reduced litters. Contrary to our prediction, there were no negative impacts of greater maternal investment and higher energy expenditure on the probability of maternal survival or future reproduction.

Pups from augmented litters grew more slowly during the lactation period were smaller at weaning and had a lower probability of survival over‐winter. Thus, although females were capable of raising more young than they gave birth to without short‐term costs of reduced survival or fecundity, our observations suggest that limitations to litter size are not due to a trade‐off in the allocation of energy, but rather due to the reduced survival of offspring from larger litters.

Examining the proximate mechanisms hypothesized to underlie life‐history trade‐offs can be challenging but is critical for a comprehensive understanding of the evolution of life histories.
Defensive symbiosis in the real world – advancing ecological studies of heritable, protective bacteria in aphids and beyond
Authors: Oliver Kerry M. , Smith Andrew H. , Russell Jacob A. 
Published: June 2013

Summary

Symbiotic microbes have become increasingly recognized to mediate interactions between natural enemies and their hosts. The ecologies of these symbioses, however, are poorly understood in many systems, and a predictive framework is needed to guide future studies. To achieve this, we focus on heritable, defensive microbes of insects. Our review of laboratory‐based studies identifies diverse bacterial species that have independently evolved to protect a range of insects against parasitoids, parasites, predators and pathogens. Although defensive mechanisms are typically unknown, some involve toxins or the upregulation of host immunity.

Despite substantial benefits of infection in the presence of natural enemies, the protective symbionts of insects are often found at intermediate levels in natural populations. Using a host‐centred population genetics approach made possible by the host restriction and cytoplasmic inheritance of these microbes, we propose that balancing selection plays a major role in symbiont maintenance, with protective benefits in the presence of enemies and infection costs in their absence. Other mediating factors are likely to be important, including temperature, superinfections and transmission dynamics.

While few studies have provided evidence for defence in the field, several studies have shown symbiont infection frequencies to be dynamic, varying across temporal and spatial gradients and food–plant associations. Newly presented data from our pea aphid research reveal that temporal shifts in defensive symbiont prevalence can be quite rapid, with Hamiltonella defensa showing 10–20% shifts around a seasonal average of c. 50%. Such findings contrast with more unidirectional changes seen in laboratory population cages, suggesting temporal changes in the costs and benefits of symbionts in the field.

To frame future research on defensive symbiont ecology, we briefly consider a range of studies needed to test laboratory‐ and field‐derived predictions on defensive symbiosis. Included are investigations of defensive mechanisms, symbiont‐driven co‐evolution and community‐level effects. We also consider the need for more thorough and highly resolved molecular diagnostics of natural infections, laboratory studies on functional differences between symbiont strains and species and studies on the relative costs and benefits of defenders in nature.

The emerging theme of symbiont‐mediated defence across eukaryotes suggests that knowledge of the functional mechanisms behind protection and natural symbiont dynamics could be key to understanding many of the world's antagonistic species interactions. Thus, the development of insects as a model for such studies holds promise for these organisms and beyond.
Trophic cascades: linking ungulates to shrub‐dependent birds and butterflies
Authors: J. Teichman Kristine , E. Nielsen Scott , Roland Jens 
Published: June 2013

Summary

Studies demonstrating trophic cascades through the loss of top‐down regulatory processes in productive and biologically diverse terrestrial ecosystems are limited.

Elk Island National Park, Alberta and surrounding protected areas have a wide range of ungulate density due to the functional loss of top predators, management for high ungulate numbers and variable hunting pressure. This provides an ideal setting for studying the effects of hyper‐abundant ungulates on vegetation and shrub‐dependent bird and butterfly species.

To examine the cascading effects of high ungulate density, we quantified vegetation characteristics and abundances of yellow warbler Dendroica petechia and Canadian tiger swallowtail Papilio canadensis under different ungulate density in and around Elk Island National Park.

Using Structural Equation Models we found that ungulate density was inversely related to shrub cover, whereas shrub cover was positively related to yellow warbler abundance. In addition, chokecherry Prunus virginiana abundance was inversely related to browse impact but positively related to P. canadensis abundance.

These results demonstrate a cascade resulting from hyper‐abundant ungulates on yellow warblers and Canadian tiger swallowtails through reductions in shrub cover and larval host plant density. The combined effect of the functional loss of top predators and management strategies that maintain high ungulate numbers can decouple top‐down regulation of productive temperate ecosystems.
The riddle of the sands: how population dynamics explains causes of high bivalve mortality
Authors: Callaway Ruth , Burdon Daryl , Deasey Anna , Mazik Krysia , Elliott Michael 
Published: June 2013

Summary

Large‐scale bivalve mortalities in estuarine and coastal habitats are a major environmental and economic concern. They may have obvious causes such as extremely cold winter temperatures, but in the absence of an apparent chain of cause and effect, a rigorous, objective approach is needed to define a probable set of factors responsible for such mortalities. This study interrogates recurrent mortalities of the cockle Cerastoderma edule L. in the Burry Inlet (South Wales, UK), where the causes of the observed die‐offs were obscure.

Spatial and temporal patterns in cockle population dynamics were analysed to determine whether mortalities were episodic or continuous, and related to cockle density. Laboratory survival experiments complemented the field studies to indicate the fitness of the cockles. The population dynamics of other species were studied to test for environmental disturbances affecting the entire benthic community.

High cockle mortalities occurred throughout the estuary in a specific cohort, namely 1‐year‐old cockles after their first winter. The mortalities did not appear to be episodic, but happened over the spring to early summer months. Cockle densities played a minor role in the decline.

The laboratory experiments showed that cockles from the Burry Inlet had higher survival rates than those collected from other areas at early life stages (0‐year class). However, by the time they reached the end of their first year (1‐year class), their survival rates declined significantly. Results suggested a physiological weakness in the cohort after the first winter.

Other benthic species did not suffer unusual mortalities.

Synthesis and applications. We emphasize that (i) interrogating patterns in population dynamics allows us to limit the number of likely causes of high bivalve mortality and generate more specific hypotheses; (ii) extending studies to other benthic species indicates the likelihood of environmental problems that affect the entire ecosystem; (iii) joined‐up field and laboratory studies suggested that probable causes of cockle mortality were primarily species‐, or even cohort‐specific, biological factors; and (iv) well‐designed monitoring systems will indicate the population dynamics of the target species on spatio‐temporal scales suitable for assessing shifts in the populations, such as unexpected extirpation.
FORUM: Sustaining ecosystem functions in a changing world: a call for an integrated approach
Authors: Tomimatsu Hiroshi , Sasaki Takehiro , Kurokawa Hiroko , Bridle Jon R. , Fontaine Colin , Kitano Jun , Stouffer Daniel B. , Vellend Mark , Bezemer T. Martijn , Fukami Tadashi , Hadly Elizabeth A. , van der Heijden Marcel G.A. , Kawata Masakado , Kéfi Sonia , Kraft Nathan J.B. , McCann Kevin S. , Mumby Peter J. , Nakashizuka Tohru , Petchey Owen L. , Romanuk Tamara N. , Suding Katharine N. , Takimoto Gaku , Urabe Jotaro , Yachi Shigeo 
Published: June 2013

Summary

With ever‐increasing human pressure on ecosystems, it is critically important to predict how ecosystem functions will respond to such human‐induced perturbations. We define perturbations as either changes to abiotic environment (e.g. eutrophication, climate change) that indirectly affects biota, or direct changes to biota (e.g. species introductions). While two lines of research in ecology, biodiversity–ecosystem function (BDEF) and ecological resilience (ER) research, have addressed this issue, both fields of research have nontrivial shortcomings in their abilities to address a wide range of realistic scenarios.

We outline how an integrated research framework may foster a deeper understanding of the functional consequences of perturbations via simultaneous application of (i) process‐based mechanistic predictions using trait‐based approaches and (ii) detection of empirical patterns of functional changes along real perturbation gradients. In this context, the complexities of ecological interactions and evolutionary perspectives should be integrated into future research.

Synthesis and applications. Management of human‐impacted ecosystems can be guided most directly by understanding the response of ecosystem functions to controllable perturbations. In particular, we need to characterize the form of a wide range of perturbation–function relationships and to draw connections between those patterns and the underlying ecological processes. We anticipate that the integrated perspectives will also be helpful for managers to derive practical implications for management from academic literature.
A slippery slope: logging alters mass–abundance scaling in ecological communities
Authors: Srinivasan Umesh 
Published: June 2013

Summary

Natural ecosystems face ever‐increasing anthropogenic threats from activities such as logging. It is therefore important to: (i) understand anthropogenic impacts on key community characteristics with implications for community structure and function and (ii) identify metrics with mechanistic underpinnings, providing a more functional understanding of anthropogenic impacts on biodiversity. Mass–abundance scaling is the most fundamental property of ecological communities, with implications on energy and resource partitioning and on how species and population traits translate to community structure and function.

In habitat patches representing a continuum of logging intensity, I examined the impact of logging on mass–abundance scaling in understorey bird species using mist netting and bird ringing. I used regression quantiles to estimate the slope and intercept of upper bound of the polygonal local‐scale mass–abundance relationship.

I show that this slope becomes more negative (and the intercept higher) as logging intensity increases. Logging might therefore significantly alter resource and energy partitioning among species in natural communities.

The mechanism underlying this pattern is likely to be an interaction between resource depletion, body size and density compensation. Larger species face more severe resource shortages from depleted resource availability and are expected to decline in abundance following logging, leading to more negative mass–abundance scaling. Density compensation by smaller species following large species decline can ‘push up’ the intercept of the mass–abundance relationship. This might result in both steeper slopes and higher intercepts in logged habitats.

Synthesis and applications. This study shows for the first time that anthropogenic habitat change can alter fundamental community properties such as mass–abundance scaling and that this property of ecological communities was better at detecting logging impacts than other standard community measures. Identifying key metrics that provide a functional understanding of anthropogenic impacts on biodiversity is a crucial need, for both the assessment of these impacts and the continued monitoring of habitat change. This study highlights the need to supplement commonly used community descriptions with more mechanistic measures of human impacts on biodiversity.