bluuebunny/crossref_metadata_2025_split huggingface dataset:
Larval diet of the frog Alsodes gargola (Leptodactylidae: Telmatobiinae) and some ecological considerations on its role in alpine and mountain aquatic environments in Patagonia
Authors: Baffico Gustavo , Úbeda Carmen 
Published: May 2006

AbstractAlsodes gargola is an endemic species from northwest Patagonia, Argentina. Its tadpoles inhabit oligotrophic high altitude lakes and mountain streams from their sources. Tadpole diet is an important yet still unknown feature of its biology. This study analyzes alimentary tract content from A. gargola tadpoles collected from several of the species' typical habitats. For each group of items eaten, frequency of occurrence and its importance in the diet according to biovolume was calculated. Tadpole feeding behavior was also observed. The most common items were periphyton and plant material. The predominant algae were diatoms (typically periphytic), chlorophytes (periphytic and some planktonic) and a few cyanobacteria. Planktonic components were found in low proportion in all samples. The animal component (mainly from periphyton) was represented by ciliates, flagellates and amoebae, and varied according to the habitats, as did vascular plant fragments. There was a wide size range of ingested particles (from 10 to 400 μm) and a wide variety of components, according to the features of each habitat. These results suggest that tadpole of A. gargola are grazers of the periphytic community and detritus gatherers. The larval diet matches the tadpole's morphological and structural adaptations to a lotic-benthic habitat (depressed body, ventral subterminal oral disc capable of adherence, dorsal eyes, low, subparallel fins) and direct observation of behavior in natural environments (slow-swimming bottom-dwelling tadpoles in still water or streams with slow-flowing microhabitats). We discuss the ecological role of slow-developing tadpoles (regulation of periphyton development), which attain large biomass in their particular ecosystems, where they are the only aquatic vertebrates.
Habits hidden underground: a review on the reproduction of the Amphisbaenia with notes on four neotropical species
Authors: Andrade Denis , Nascimento Luciana , Abe Augusto 
Published: May 2006

AbstractWe review the information currently available on the reproduction of the Amphisbaenia and provide original data on the reproductive biology of four Neotropical species: Amphisbaena alba; A. mertensi; Cercolophia roberti, and Leposternon infraorbitale. In total, we compiled data for 22 species: 17 Amphisbaenidae, 1 Rhineuridae, 3 Bipedidae, and 1 Trogonophidae. The majority of the species were oviparous with the exceptions of Loveridgea ionidesii, Monopeltis anchietae, M. capensis, and Trogonophis wiegmanni. Viviparity was interpreted as a derived trait that evolved independently for at least 3 times within the Amphisbaenia. In most species, reproduction is synchronized with the hot and rainy season and seems to vary with latitude. Although Amphisbaenia eggs have been found in ant nests, it remains disputable whether this is an obligatory or even a preferable location for egg-laying. Incubation time in A. mertensii lasts 59 days and this is the first report encompassing egg-laying to hatching for any Amphisbaenia species. Nonetheless, a two months incubation period seems to be the common rule for oviparous Amphisbaenia. The general pattern of reproductive output in Amphisbaenia is characterized by a low number of eggs/embryos per clutch whose individual size is comparatively large in relation to adult body size. Eggs are markedly elongated on the long axis and arranged in-line within the abdominal cavity possibly to prevent/diminish biomechanic drawbacks of egg bearing. Hatchlings of A. mertensi possess an egg-tooth implanted at the upper jaw, exhibit positive geotropism, and display defensive behaviors known to be present in adults. Our review shows that our current knowledge of Amphisbaenia reproduction is fragmentary, often based on the examination of small samples, and heavily dependent on the publication of anedoctal observations. Future publications on this subject are encouraged.
A Lightweight Observation System for Atmospheric Carbon Dioxide Concentration Using a Small Unmanned Aerial Vehicle
Authors: Watai T. , Machida T. , Ishizaki N. , Inoue G. 
Published: May 2006

Abstract
To make the investigation of the temporal and spatial variations of atmospheric CO2 in and above the planetary boundary layer more flexible and economical, a lightweight observation system using a small unmanned aerial vehicle has been developed whose flight path is preset using GPS. The total weight of the CO2 measurement device carried inside the vehicle is about 3.5 kg. The device is equipped with both flow and pressure controllers and can be used to measure atmospheric CO2 from the ground surface to a maximum altitude of about 3000 m. The response time of the instrument is about 20 s, with a precision of about ±0.26 ppm. The observation system is easy to handle and can be easily and quickly deployed at a site to make frequent measurements in and above the boundary layer. Compared to the deployment of a piloted aircraft the system shows distinctive advantages, in addition to being more affordable. To test the system, preliminary measurements over a boreal forest area in Japan in the summer of 2000 have been conducted. The results indicate that the unmanned aerial vehicle measurement system provides an affordable platform that can be used to obtain quantitative understanding of the temporal and vertical variations of atmospheric CO2 in and above the planetary boundary layer.
Assimilation of Ice Concentration in an Ice–Ocean Model
Authors: Lindsay R. W. , Zhang J. 
Published: May 2006

Abstract
Ice concentration is a critical parameter of the polar marine environment because of the large effect sea ice has on the surface albedo and heat exchange between the atmosphere and the ocean. Simulations of the energy exchange processes in models would benefit if the ice concentration were represented more accurately. Reanalysis simulations that use historical wind and temperature fields may develop erroneous ice concentration estimates; these can be corrected by using observed ice concentration fields. The ice concentration assimilation presented here is a new method based on nudging the model ice concentration toward the observed concentration in a manner that emphasizes the ice extent and minimizes the effect of observational errors in the interior of the pack. The nudging weight is a nonlinear function of the difference between the model and the observed ice concentration. The simulated ice extent is improved with the assimilation of ice concentration but is not identical to the observed extent. The simulated ice draft is compared to that measured by upward-looking sonars on submarines and moorings. Significant improvements in the ice draft comparisons are obtained with assimilation of ice concentration alone and even more with assimilation of both ice concentration and ice velocity observations.
Calibration Technique for Polarization-Sensitive Lidars
Authors: Alvarez J. M. , Vaughan M. A. , Hostetler C. A. , Hunt W. H. , Winker D. M. 
Published: May 2006

AbstractPolarization-sensitive lidars have proven to be highly effective in discriminating between spherical and nonspherical particles in the atmosphere. These lidars use a linearly polarized laser and are equipped with a receiver that can separately measure the components of the return signal polarized parallel and perpendicular to the outgoing beam. In this work a technique for calibrating polarization-sensitive lidars is described that was originally developed at NASA's Langley Research Center (LaRC) and has been used continually over the past 15 yr. The procedure uses a rotatable half-wave plate inserted into the optical path of the lidar receiver to introduce controlled amounts of polarization cross talk into a sequence of atmospheric backscatter measurements. Solving the resulting system of nonlinear equations generates the system calibration constants (gain ratio and offset angle) required for deriving calibrated measurements of depolarization ratio from the lidar signals. In addition, this procedure also determines the mean depolarization ratio within the region of the atmosphere that is analyzed. Simulations and error propagation studies show the method to be both reliable and well behaved. Operational details of the technique are illustrated using measurements obtained as part of LaRC's participation in the First International Satellite Cloud Climatology Project Regional Experiment.
Comparison of Collocated Automated (NCECONet) and Manual (COOP) Climate Observations in North Carolina
Authors: Holder Christopher , Boyles Ryan , Syed Ameenulla , Niyogi Dev , Raman Sethu 
Published: May 2006

Abstract
The National Weather Service's Cooperative Observer Program (COOP) is a valuable climate data resource that provides manually observed information on temperature and precipitation across the nation. These data are part of the climate dataset and continue to be used in evaluating weather and climate models. Increasingly, weather and climate information is also available from automated weather stations. A comparison between these two observing methods is performed in North Carolina, where 13 of these stations are collocated. Results indicate that, without correcting the data for differing observation times, daily temperature observations are generally in good agreement (0.96 Pearson product–moment correlation for minimum temperature, 0.89 for maximum temperature). Daily rainfall values recorded by the two different systems correlate poorly (0.44), but the correlations are improved (to 0.91) when corrections are made for the differences in observation times between the COOP and automated stations. Daily rainfall correlations especially improve with rainfall amounts less than 50 mm day−1. Temperature and rainfall have high correlation (nearly 1.00 for maximum and minimum temperatures, 0.97 for rainfall) when monthly averages are used. Differences of the data between the two platforms consistently indicate that COOP instruments may be recording warmer maximum temperatures, cooler minimum temperatures, and larger amounts of rainfall, especially with higher rainfall rates. Root-mean-square errors are reduced by up to 71% with the day-shift and hourly corrections.
This study shows that COOP and automated data [such as from the North Carolina Environment and Climate Observing Network (NCECONet)] can, with simple corrections, be used in conjunction for various climate analysis applications such as climate change and site-to-site comparisons. This allows a higher spatial density of data and a larger density of environmental parameters, thus potentially improving the accuracy of the data that are relayed to the public and used in climate studies.
Forward-in-Time-/Backward-in-Time-Trajectory (FITT/BITT) Modeling of Particles and Organisms in the Coastal Ocean*
Authors: Batchelder Harold P. 
Published: May 2006

AbstractLagrangian particle-tracking models (LPTMs) were used to identify sources, destinations, and transport pathways of particles (plankton). The LPTM simulations were forced using stored fields from the Spectral Element Ocean Model simulation for a coastal upwelling system having idealized geometry, bathymetry, and simple wind forcing. Forward-in-time-trajectory (FITT) simulations are common in ocean science, although they often do not include diffusion. Results from LPTM comparisons with and without diffusion suggest that ignoring diffusion can lead to incorrect identification of source or destination regions. FITT is efficient for identifying destinations from known sources, but inefficient for identifying sources from known destinations (or receptors). Backward-in-time-trajectory (BITT) modeling from known destinations efficiently identifies sources, or particle positions, at earlier times. Although advection and some biological processes (e.g., growth) are reversible and amenable to BITT simulations, other processes, such as physical diffusion, reproduction, and mortality, are not time reversible. The reliability of BITT-derived estimates of prior particle positions was evaluated using a BITT followed by a FITT coupled approach. The results suggest that BITT approaches are valuable in identifying probability densities of prior positions. Such information is particularly useful in the ocean sciences where many of the interesting questions concern where particles (e.g., plankton, meroplankton) have been (or came from) rather than where they are headed (identifying the destination). BITT simulations provide a computationally efficient technique to examine these questions.
Retrieving Cloud Characteristics from Ground-Based Daytime Color All-Sky Images
Authors: Long C. N. , Sabburg J. M. , Calbó J. , Pagès D. 
Published: May 2006

Abstract
A discussion is presented of daytime sky imaging and techniques that may be applied to the analysis of full-color sky images to infer cloud macrophysical properties. Descriptions of two different types of sky-imaging systems developed by the authors are presented, one of which has been developed into a commercially available instrument. Retrievals of fractional sky cover from automated processing methods are compared to human retrievals, both from direct observations and visual analyses of sky images. Although some uncertainty exists in fractional sky cover retrievals from sky images, this uncertainty is no greater than that attached to human observations for the commercially available sky-imager retrievals. Thus, the application of automatic digital image processing techniques on sky images is a useful method to complement, or even replace, traditional human observations of sky cover and, potentially, cloud type. Additionally, the possibilities for inferring other cloud parameters such as cloud brokenness and solar obstruction further enhance the usefulness of sky imagers.
Validation of the AATSR Meteo Product Sea Surface Temperature
Authors: O'Carroll A. G. , Watts J. G. , Horrocks L. A. , Saunders R. W. , Rayner N. A. 
Published: May 2006

AbstractThe Advanced Along Track Scanning Radiometer (AATSR) Sea Surface Temperature (SST) Meteo product, a fast-delivery level-2 product at 10 arc min spatial resolution, has been available from the European Space Agency (ESA) since 19 August 2002. Validation has been performed on these data at the Met Office on a daily basis, with a 2-day lag from data receipt. Meteo product skin SSTs have been compared with point measurements of buoy SST, a 1° climate SST analysis field compiled from in situ measurements and Advanced Very High Resolution Radiometer (AVHRR) SSTs, and a 5° latitude–longitude 5-day averaged in situ dataset. Comparisons of the AATSR Meteo product against Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) SSTs are also presented. These validation results have confirmed the AATSR Meteo product skin SST to be within ±0.3 K of in situ data.Comparisons of the AATSR skin SSTs against buoy SSTs, from 19 August 2002 to 20 August 2003, give a mean difference (AATSR – buoy) of 0.04 K (standard deviation = 0.28 K) during nighttime, and a mean difference of 0.02 K (standard deviation = 0.39 K) during the day. Analyses of the buoy matchups have shown that there is no cool skin effect observed in the nighttime observations, implying that the three-channel AATSR product skin SST may be 0.1–0.2 K too warm. Comparisons with TMI SSTs confirm that the lower-latitude SSTs are not significantly affected by residual cloud contamination.
An Improvement to the High-Spectral-Resolution CO2-Slicing Cloud-Top Altitude Retrieval
Authors: Holz Robert E. , Ackerman Steve , Antonelli Paolo , Nagle Fred , Knuteson Robert O. , McGill Matthew , Hlavka Dennis L. , Hart William D. 
Published: May 2006

AbstractAn improvement to high-spectral-resolution infrared cloud-top altitude retrievals is compared to existing retrieval methods and cloud lidar measurements. The new method, CO2 sorting, determines optimal channel pairs to which the CO2 slicing retrieval will be applied. The new retrieval is applied to aircraft Scanning High-Resolution Interferometer Sounder (S-HIS) measurements. The results are compared to existing passive retrieval methods and coincident Cloud Physics Lidar (CPL) measurements. It is demonstrated that when CO2 sorting is used to select channel pairs for CO2 slicing there is an improvement in the retrieved cloud heights when compared to the CPL for the optically thin clouds (total optical depths less than 1.0). For geometrically thick but tenuous clouds, the infrared retrieved cloud tops underestimated the cloud height, when compared to those of the CPL, by greater than 2.5 km. For these cases the cloud heights retrieved by the S-HIS correlated closely with the level at which the CPL-integrated cloud optical depth was approximately 1.0.
High interleukin-10 production is associated with low antibody response to influenza vaccination in the elderly
Authors: Corsini Emanuela , Vismara Luigi , Lucchi Laura , Viviani Barbara , Govoni Stefano , Galli Corrado L , Marinovich Marina , Racchi Marco 
Published: May 2006

Abstract
The present study was designed to determine the correlation among dehydroepiandrosterone (DHEA), cortisol plasma levels, and immune functionality at the time of vaccination with antibody response to influenza vaccination in young and old, healthy volunteers. Fifty-two elderly subjects, ages 63–85 years, and 14 young subjects, ages 26–41 years, entered the study. Plasma levels of DHEA and cortisol and in vitro cytokine production in response to lipopolysaccharide (LPS) and phytohaemagglutinin (PHA) by peripheral blood leukocytes were assessed at the time of vaccination, and antibody titer was measured before and 18 days after influenza virus vaccination. Elderly subjects were characterized by an increase in the cortisol:DHEA ratio, mainly as a result of a decrease in DHEA. A decrease in LPS-induced tumor necrosis factor α (TNF-α), increased PHA-induced interleukin-10 (IL-10) release, and similar PHA-induced interferon-γ production were observed in elderly subjects compared with young volunteers. Lower antibody titer to influenza A virus was observed in elderly individuals, and the seroconversion factor was found to be correlated inversely with IL-10 production and correlated directly with TNF-α production and to a lesser extent, with the plasma level of DHEA. These results suggest that altered cytokine production in elderly subjects at the moment of vaccination can be predictive of a low response to influenza vaccination and warrant the study of strategies to improve protection afforded by the use of vaccines.
Data and safety monitoring in social behavioral intervention trials: the REACH II experience
Authors: Czaja Sara J , Schulz Richard , Belle Steven H , Burgio Louis D , Armstrong Nell , Gitlin Laura N , Coon David W , Martindale-Adams Jennifer , Klinger Julie , Stahl Sidney M 
Published: May 2006

Background Psychosocial and behavioral interventions trials targeting a broad range of complex social and behavioral problems such as smoking, obesity and family caregiving have proliferated in the past 30 years. At the same time the use of Data and Safety Monitoring Boards (DSMBs) to monitor the progress and quality of intervention trials and the safety of study participants has increased substantially. Most of the existing literature and guidelines for safety monitoring and reporting of adverse events focuses on medical interventions. Consequently, there is little guidance for investigators conducting social and behavior trials. Purpose This paper summarizes how issues associated with safety monitoring and adverse event reporting were handled in the Resources for Enhancing Alzheimer's Caregiver Health (REACH II) program, a multi-site randomized clinical trial, funded by the National Institutes on Aging (NIA) and the National Institutes of Nursing Research (NINR), that tested the efficacy of a multicomponent social/behavioral intervention for caregivers of persons with Alzheimer's disease. Methods A task force was formed to define adverse events for the trial and protocols for reporting and resolving events that occurred. The task force conducted a review of existing polices and protocols for data and safety monitoring and adverse event reporting and identified potential risks particular to the study population. An informal survey regarding data and safety monitoring procedures with investigators on psychosocial intervention trials was also conducted. Results Two categories of events were defined for both caregivers and patients; adverse events and safety alerts. A distinction was also made between events detected at baseline assessment and those detected post-randomization. Standardized protocols were also developed for the reporting and resolution of events that occurred and training of study personnel. Results from the informal survey indicated wide variability in practices for data safety and monitoring across psychosocial intervention trials. Conclusions Overall, the REACH II experience demonstrates that existing guidelines regarding safety monitoring and adverse event reporting pose unique challenges for social/behavioral intervention trials. Challenges encountered in the REACH II program included defining and classifying adverse events, defining “resolution” of adverse events and attributing causes for events that occurred. These challenges are highlighted and recommendations for addressing them in future studies are discussed.
The feasibility of clinical endpoint trials in HIV infection in the highly active antiretroviral treatment (HAART) era
Authors: Mocroft A , Neaton J , Bebchuk J , Staszewski S , Antunes F , Knysz B , Law M , Phillips A N , Lundgren J D 
Published: May 2006

Background Planning clinical-endpoint trials in patients with HIV remain difficult as long-term follow-up of many patients is required. Cohort studies of patients with HIV can provide key estimates of the likely disease progression, required sample size and follow-up. Objectives To verify the assumptions used in designing ESPRIT, a large randomized clinical trial assessing the clinical benefit of interleukin-2 treatment in patients with HIV infection, to use EuroSIDA to mimic the inclusion criterion of ESPRIT in order to compare the observed event rate in ESPRIT with the projected rate in EuroSIDA, and to project the required length of ESPRIT. Methods Patients in EuroSIDA who satisfied the ESPRIT recruitment criteria were selected. Patients were followed from baseline to new AIDS or death. Results The incidence of clinical progression in the selected EuroSIDA patients ( N - 4482) was 1.5 per 100 PYFU (95% CI 1.3–1.7), and did not increase with increasing time from baseline, contrary to what was assumed in the design of the ESPRIT trial. In ESPRIT (N - 4150), for which the comparative data remain blinded, the incidence was 1.1 per 100 PYFU (95% CI 0.9–1.3), with no increase over time. The average follow-up required to complete ESPRIT and accrue the 320 events required by protocol would be seven years, 10 months using the projected rates from the EuroSIDA study, and seven years, 11 months if the observed event rate in ESPRIT continued unchanged. Limitations Differences between patients recruited to observational studies or clinical trials cannot always be adjusted for. Conclusions Event rates in EuroSIDA were similar in the first two years to those used in the design of ESPRIT, but did not increase over time, leading to an increase in the expected duration of ESPRIT. Clinical endpoint trials in HIV infection remain feasible, and large cohort studies are critical to the planning and ongoing assessment of design assumptions in such trials. The underlying assumptions of the clinical trial should be re-examined to ensure the original trial assumptions remain valid.