bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous Dielectric and Fourier Transform near Infrared Spectroscopy to Monitor a Polyepoxy Curing Process
Authors: Durand Alexandra , Hassi Laïla , Lachenal Gilbert , Stevenson Isabelle , Seytre Gérard , Boiteux Gisèle
Published: May 2009

In this paper, a laboratory-made system which allows the coupling of dielectric analysis and Fourier transform near infrared spectroscopy (FT-NIR) to follow the cure of polyepoxy reactive systems is presented. The dielectric measurements were obtained using an interdigitated electrode. In situ monitoring of the extent of the reaction was carried out from room temperature up to 160°C using fibre-optic FT-NIR spectroscopy. The appliance for simultaneous measurement is described and the advantages and limitations are briefly discussed. Dielectric analysis and near infrared spectroscopy are complementary since the former can detect the vitrification phenomenon and the latter can give access to the extent of the reaction. When combined, the two spectroscopies can detect indirectly, after calibration, the extent of a reaction from the electric degree of transformation and vice versa with the help of chemometrics.
Ability of near Infrared Spectroscopy to Predict Pork Technological Traits
Authors: Čandek-Potokar M. , Prevolnik M. , Škrlep M.
Published: May 2009

The predictive ability of near infrared spectroscopy was studied for some fresh meat quality traits: pH24, colour parameters (L*, a* and b*) and drip loss (measured after 24 and 48 hours). The material used in this study involved 296 pig longissimus dorsi muscle samples originating from various hybrids of different carcass weight, two abattoirs and five series of slaughter. Samples were scanned both intact and minced over the wavelength range 400–2500 nm using an NIRSystems model 6500 spectrophotometer. Modified partial least squares (PLS) was used to develop models and to obtain calibration statistics: coefficient of determination of calibration and cross-validation ( R2 CV) and standard error of calibration and cross-validation ( SECV). The predictive ability of near infrared (NIR) spectroscopy was additionally tested on an independent set of samples and prediction statistics calculated. Best calibrations were obtained on intact meat samples using the spectral range 400–1100 nm. For these models, the R2 CV values were in the range of 0.54–0.79 and SECV values were 0.10 for pH24, 2.4 for L*, 0.8 for a*, 0.9 for b*, 1.6% for drip24 and 2.1% for drip48. Within-sample standard deviation (repeatability) of reference measurements was 0.05 for pH24, 3.1 for L*, 1.0 for a*, 0.9 for b*, 1.1% for drip24 and 1.3% for drip48, indicating limitations in NIR spectroscopy's predictive ability due to the precision of reference methods used for calibration. Prediction errors obtained on the validation set (0.08 for pH24, 2.0 for L*, 0.8 for a*, 0.7 for b*, 1.4% for drip24 and 1.7% for drip48) were in agreement with cross-validation results. Similar model performance was found for driploss prediction (PLS regression) based on spectral information or on a combination of pH24, L*, a*, b*.
Multi-Product Calibration Models of near Infrared Spectra of Foods
Authors: Micklander Elisabeth , Kjeldahl Karin , Egebo Max , Nørgaard Lars
Published: May 2009

Maintenance of multivariate calibration models can be laborious when using near infrared (NIR) for quantitative analysis, thus to save time on updates of the multivariate calibration models it is worthwhile to investigate if multi-product models for the content of a given constituent in many different foods can be developed. In this study eight different food products with known fat content (%) were analysed with NIR spectroscopy in the range from 850 to 1048 nm and the predictive performance of calibration models developed on each product was compared with multi-product calibration models including all eight food products. Different pre-processing techniques (multiplicative scatter correction, first and second order derivatives, extended inverted signal correction, standard normal variate transformation and second derivative combined with multiplicative scatter correction) and five linear and non-linear calibration models (partial least squares regression, neural networks and three local regression techniques) were evaluated. Also, simple single-spectral match was tested. In total, 4382 samples were analysed covering all eight products and a fat content range of 0.03 to 86.25%. Two thirds of the samples were used for model development and one third of the samples were used for independent test set validation. Not unexpectedly, the results showed that multi-product models generally result in less accurate and precise predictions than one-product models. Of the calibration methods tested, the local regression models gave the smallest range-relative root mean square error of prediction for multi-product models. Multi-product models also worked well using neural networks, whereas partial least squares regression could not handle the non-linear trend in data. Both neural network and local regression models were found to be suitable methods for substituting several one-product models with one multi-product model. The relative prediction errors for the best local regression model were in the range 2.2 to 4.4% for the eight products. Predictions based on using the fat content of the sample in the calibration set with the most similar spectrum (smallest Euclidian distance) to the test sample as the predicted value were inferior to the neural network and local regression methods, but worked surprisingly well.
Effects of Spectral Resolution on the Determination of Glucose in a Simulated Biological Matrix by Fourier Transform near Infrared Spectrometry
Authors: Kramer Kirsten E. , Small Gary W.
Published: May 2009

The effects of spectral resolution on the performance of partial least-squares (PLS) calibration models were studied in the context of an analysis for physiological levels of glucose by Fourier transform near infrared (NIR) spectrometry in the combination region of 5000 to 4000 cm−1. Employing a simulated biological matrix of varying levels of triacetin and bovine serum albumin in phosphate buffer, two spectral data sets were evaluated. Single-sided interferograms consisting of 16,384 points collected over a 15,801 cm−1 bandwidth were Fourier processed to yield spectra with a nominal 2 cm−1 point spacing. These interferograms were then progressively truncated before Fourier processing to form sets of spectra with reduced resolution. The lower-resolution spectra were also computed with varying levels of zero-filling to evaluate the effects of spectral dimensionality on the PLS models. Across the levels of resolution and zero-filling, 21 parallel groups of spectra were computed with each of the two data sets. Calibration studies were then performed with spectra in absorbance units. Predictive models for glucose were optimised in terms of spectral range, the number of PLS latent variables and the parameters of a pre-processing Fourier filter. Models were evaluated for their performance in both short-term and long-term predictions. Through this research, it was found that models based on spectra with a nominal resolution of 16 cm−1 performed as well as those computed with higher-resolution spectra. Over the range of 1–20 mM glucose, these models achieved values of the standard error of prediction ( SEP) in the range of 0.5 mM for short-term predictions and 0.8 mM for predictions with spectra collected more than 200 days after the calibration data. These results are significant because they help to define the required instrumental characteristics of a potential dedicated NIR glucose sensor.
Prognostic Value of Cerebral near Infrared Spectroscopy and Cerebral Blood Flow Velocity for Developing Acute Mountain Sickness at High Altitudes
Authors: Litscher Gerhard , Hadolt Irmgard , Ausserer Harald , Feddersen Berend
Published: May 2009

Using near infrared (NIR) spectroscopy and transcranial Doppler sonography (TCD), we investigated the effects of high altitude in a group of 17 healthy volunteers (mean age ± standard deviation: 46.1 ± 13.1 years) during a common trekking tour in the Nepal Himalayas, lasting 22 days (2850 m to 5600 m). Values of regional cerebral oxygen saturation (rSO2) obtained by an INVOS 5100 system significantly decreased ( p < 0.001) compared to baseline (130 m) at an altitude of 4450 m. Mean blood flow velocity (v m) in the middle cerebral artery measured by a portable Smart Dop equipment significantly increased ( p < 0.05) compared to baseline (130 m) also at an altitude of 4450 m. The results showed further that all three subjects who developed acute mountain sickness (AMS) and who were not able to continue the trek up to 5050 m, had rSO2 or v m values out of the normal range at baseline measurements 130 m above sea level 53 days before starting the tour. Simultaneous measurement of cerebral rSO2 and v m parameters could be able to enhance the prognostic accuracy for the development of AMS in the mountain trekking population.
Determination of Total Carbon and Nitrogen Content in a Range of Tropical Soils Using near Infrared Spectroscopy: Influence of Replication and Sample Grinding and Drying
Authors: Barthès Bernard G. , Brunet Didier , Ferrer Henri , Chotte Jean-Luc , Feller Christian
Published: May 2009

Near infrared (NIR) reflectance spectroscopy has been receiving increased attention for the rapid and inexpensive determination of soil properties and of total carbon (Ct) and nitrogen content (Nt) in particular. However, methodological aspects such as sample grinding and drying or replication have not been addressed extensively. The objectives of the paper were, thus, to assess how NIR predictions of Ct and Nt were affected by sample grinding (2 mm sieving vs. 0.2 mm grinding), drying (air-drying vs oven-drying at 40°C during 24 h) and replication (use of one to six sub-samples to determine average spectra). This was performed on a range of tropical soils that differed widely in mineralogy (low and high activity clay soils, allophanic soils) and texture (sandy to clayey). The accuracy of the NIR predictions of Ct and Nt was higher with oven-dried compared to air-dried samples and, more markedly, with 0.2 mm ground compared to 2 mm sieved samples. Replication had a positive effect on NIR predictions when 2 mm sieved samples were used, especially for air-dried samples, but this effect was not clear with 0.2 mm ground samples. Thus, the most accurate predictions of Ct and Nt were obtained with oven-dried finely ground samples, with limited response to sample replication. Accurate predictions were, however, also obtained with four replicates on oven-dried 2 mm sieved samples. Acceptable and less tedious results could, thus, be achieved when replacing fine grinding by replication. Even with this procedure, the r2 between predicted (NIR) and measured (reference) values was 0.9 and the ratio of standard error of prediction to mean ( CV%) was 20% which can be considered satisfactory for the heterogeneous sample set under study.
American Economic Journal: Microeconomics
Authors: Postlewaite Andrew
Published: May 2009

AEJ Micro publishes papers focusing on microeconomic theory, industrial organization, and the microeconomic aspects of international trade, political economy, and finance. The journal will publish theoretical work as well as both empirical and experimental work with a theoretical framework.
Initiating antiretroviral treatment in a resource-constrained setting: does clinical staging effectively identify patients in need?
Authors: Torpey K , Lartey M , Amenyah R , Addo N A , Obeng-Baah J , Rahman Y , Suzuki C , Mukadi Y D , Colebunders R
Published: May 2009

In industrialized countries, the initiation of antiretroviral therapy (ART) is based on virological, immunological and clinical markers. The objective of this study was to identify treatment gaps when ART initiation is based on clinical staging alone. The method employed was a retrospective study of 5784 patients enrolled in an HIV treatment programme in two urban and two rural sites in Ghana. Of the patients, 29.5% were in clinical Stages I and II and had a CD4+ T-lymphocyte count less than 200 cells/mm3. Significantly more patients in clinical Stage I from urban sites (37.0%) had a CD4+ T-lymphocyte count less than 200 cells/mm3 as compared with patients from rural sites (23.8%) ( P value <0.05). In addition, more men (39.9%) in clinical Stage I had a CD4+ T-lymphocyte count less than 200 cells/mm3 when compared with women (27.4%) ( P value <0.05). In conclusion, clinical staging cannot identify a relatively large number of patients who need ART. A wider availability of CD4+ T-lymphocyte count testing will optimize the identification of patients eligible for ART.
Drug resistance in the Chinese National Pediatric Highly Active Antiretroviral Therapy Cohort: implications for paediatric treatment in the developing world
Authors: Zhang F , Haberer J , Wei H , Wang N , Chu A , Zhao Y , Zhao H
Published: May 2009

China's National Pediatric ART Program began in 2005, in which 32 ART-experienced and 51 antiretroviral therapy (ART)-naïve children received paediatric formulations of (zidovudine or stavudine) plus lamivudine plus (nevirapine or efavirenz). Reverse transcriptase sequencing and analysis was performed on plasma samples with >1000 HIV copies/mL after one year of treatment. Thirty-four samples were sequenced. Nearly all patients had nucleoside reverse transcriptase inhibitor and non-nucleoside reverse transcriptase inhibitor mutations. High/intermediate resistance was found to lamivudine/emtricitabine in 31 patients; to didanosine, abacavir, stavudine and zidovudine in 18 patients; and to tenofovir in 11 patients. All had high-level resistance to nevirapine; all but one had high/intermediate-level resistance to efavirenz. Viral load was the only cohort characteristic significantly associated with developing resistance. Resistance to zidovudine, stavudine and tenofovir was more common in ART-experienced versus ART-naïve patients ( P = 0.02–0.05). Drug resistance is high in this cohort. Second-line therapy will require additional ART strategies and options, which are currently unavailable in most developing settings.
Persistent genital arousal disorder: a review of the literature and recommendations for management
Authors: Goldmeier D , Mears A , Hiller J , Crowley T
Published: May 2009

Persistent genital arousal disorder is a newly recognized condition that is poorly understood. There is a paucity of research in this area and there are concerns as to the validity of the results of what little research there has been. This article aims to draw together current literature on this topic and provide readers with guidance on the management of this condition. This includes a working definition, an exploration of possible aetiologies within the confines of current knowledge, practical advice regarding assessment, management and auditable outcomes of practice.
Constraints on natural altruism
Authors: Wynn Karen
Published: May 2009

This article is a commentary on ‘The roots of human altruism’ (Warneken & Tomasello, 2009).
In situ Measures of Head Impact Acceleration in NCAA Division I Men’s Ice Hockey: Implications for ASTM F1045 and Other Ice Hockey Helmet Standards
Authors: Gwin Joseph T. , Chu Jeffery J. , McAllister Thomas A. , Greenwald Richard M.
Published: May 2009

A pilot study was performed to measure head impact accelerations in collegiate men’s ice hockey during the 2005–2007 seasons using helmets instrumented with Head Impact Telemetry System technology to monitor and record linear head accelerations and impact locations in situ. The objectives of this study were (1) to quantify the relationship between resultant peak linear head acceleration and impact location for in situ head impacts in collegiate men’s ice hockey, (2) to quantify the frequency and severity of impacts to the facemask, and (3) to determine if in situ impacts occurred such that the peak resultant linear head acceleration was higher than the peak resultant linear headform acceleration from a 40-in. linear drop (as in ASTM F1045–99) on the same helmet at a similar impact location. Voluntary participants (n=5 and 7 for years 1 and 2, respectively) wore instrumented helmets which monitored head impact accelerations sustained by each player during all games and practices. Head impact data were grouped by impact location into five bins representing top, back, side, forehead, and facemask. Forehead impacts represented impacts to the helmet shell as distinguished from facemask impacts. Additionally, a sample instrumented helmet was impacted in the laboratory at forehead, side, rear, and top impact locations (40-in. drop, three trials per location, test setup as specified in ASTM F1045-99). The mean peak resultant linear headform acceleration for each impact location was determined for analysis. Of the 4,393 recorded head impacts, 33.2 % were to the back of the helmet. This percentage increased to 59.2 % for impacts above 70 g. Facemask impacts accounted for 12.2 % of all impacts but only 2.4 % of impacts above 70 g. Over two seasons, five in situ impacts occurred such that the peak resultant linear head acceleration was greater than the mean peak resultant linear headform acceleration for a corresponding impact location in the laboratory. This study found that the most common impact location in ice hockey, particularly for impacts with higher peak linear accelerations, was the back of the head and demonstrated that facemask impacts were typically of a lower magnitude. The five impacts or ∼0.4 per player/season that exceeded the peak linear acceleration associated with 40-in. laboratory drops suggested that the impact energy specified in ASTM F1045 may not reflect the highest energy impacts seen in situ.
Atomic pair distribution function analysis of materials containing crystalline and amorphous phases
Authors: Proffen Thomas , Page Katharine L. , McLain Sylvia E. , Clausen Bjorn , Darling Timothy W. , TenCate James A. , Lee Seung-Yub , Ustundag Ersan
Published: May 2009

The atomic pair distribution function (PDF) approach has been used to study the local structure of liquids, glasses and disordered crystalline materials. In this paper, we demonstrate the use of the PDF method to investigate systems containing a crystalline and an amorphous structural phase. We present two examples: Bulk metallic glass with crystalline reinforcements and Fontainebleau sandstone, where an unexpected glassy phase was discovered. In this paper we also discuss the refinement methods used in detail.
Determination of phonon dispersion relations by X-ray thermal diffuse scattering
Authors: Xu Ruqing , Chiang Tai C.
Published: May 2009

Thermal diffuse scattering (TDS) of X-rays from crystals contains information on phonons. This paper reviews the general theory of TDS and some recent experiments aimed at further developing TDS into a useful and efficient method for studying phonon dispersion relations.
Modelling disorder in 3,3′-dimethoxybenzil, C16H14O4
Authors: Goossens Darren J. , Welberry T. Richard , Heerdegen Aidan P. , Edwards Alison J.
Published: May 2009

This work is part of an extended study of benzil (C14H10O2) and some of its derivatives which aims to understand the role of molecular flexibility in crystal packing and polymorphism. Significant steps have been made in modelling the structured thermal diffuse scattering from 3,3′-dimethoxybenzil, C16H14O4. It appears that the structure can be considered as a stack of layers of molecules in which interactions are strongest within the layers. The layers interact weakly along the a direction but more strongly along c, so shearing of the planes relative to each other is energetically likely. The molecule must be treated as flexible for a good model to be found.
Diffuse scattering in the layered perovskites
Authors: Campbell Branton J.
Published: May 2009

Single-crystal X-ray and neutron diffuse scattering techniques have been used to probe a variety of short-range displacive and magnetic orderings in the layered transition-metal perovskites which arise due to the intimate coupling of their structural, electronic and magnetic degrees of freedom. The present work reviews recent analyses that have successfully modeled short-range intralayer and/or interlayer correlations in these materials leading to useful physical insights, and describes the methods employed within a general formulation of the disordered structure function.
The Functional Transfer of Genes From the Mitochondria to the Nucleus: The Effects of Selection, Mutation, Population Size and Rate of Self-Fertilization
Authors: Brandvain Yaniv , Wade Michael J
Published: May 2009

The transfer of mitochondrial genes to the nucleus is a recurrent and consistent feature of eukaryotic genome evolution. Although many theories have been proposed to explain such transfers, little relevant data exist. The observation that clonal and self-fertilizing plants transfer more mitochondrial genes to their nuclei than do outcrossing plants contradicts predictions of major theories based on nuclear recombination and leaves a gap in our conceptual understanding how the observed pattern of gene transfer could arise. Here, with a series of deterministic and stochastic simulations, we show how epistatic selection and relative mutation rates of mitochondrial and nuclear genes influence mitochondrial-to-nuclear gene transfer. Specifically, we show that when there is a benefit to having a mitochondrial gene present in the nucleus, but absent in the mitochondria, self-fertilization dramatically increases both the rate and the probability of gene transfer. However, absent such a benefit, when mitochondrial mutation rates exceed those of the nucleus, self-fertilization decreases the rate and probability of transfer. This latter effect, however, is much weaker than the former. Our results are relevant to understanding the probabilities of fixation when loci in different genomes interact.
One- and Two-Locus Population Models With Differential Viability Between Sexes: Parallels Between Haploid Parental Selection and Genomic Imprinting
Authors: Yanchukov Alexey
Published: May 2009

A model of genomic imprinting with complete inactivation of the imprinted allele is shown to be formally equivalent to the haploid model of parental selection. When single-locus dynamics are considered, an internal equilibrium is possible only if selection acts in the opposite directions in males and females. I study a two-locus version of the latter model, in which maternal and paternal effects are attributed to the single alleles at two different loci. A necessary condition for the allele frequency equilibria to remain on the linkage equilibrium surface is the multiplicative interaction between maternal and paternal fitness parameters. In this case the equilibrium dynamics are independent at both loci and results from the single-locus model apply. When fitness parameters are additive, analytic treatment was not possible but numerical simulations revealed that stable polymorphism characterized by association between loci is possible only in several special cases in which maternal and paternal fitness contributions are precisely balanced. As in the single-locus case, antagonistic selection in males and females is a necessary condition for the maintenance of polymorphism. I also show that the above two-locus results of the parental selection model are very sensitive to the inclusion of weak directional selection on the individual's own genotypes.
Evolution of Neo-Sex Chromosomes inSilene diclinis
Authors: Howell Elaine C , Armstrong Susan J , Filatov Dmitry A
Published: May 2009

A small cluster of dioecious species in the plant genus Silene has evolved chromosomal sex determination and sex chromosomes relatively recently, within the last 10 million years (MY). Five dioecious Silene species (section Elisanthe) are very closely related (1–2 MY of divergence) and it was previously thought that all five have similar sex chromosomes. Here we demonstrate that in one of these species, Silene diclinis, the sex chromosomes have been significantly rearranged, resulting in the formation of neo-sex chromosomes. Fluorescence in situ hybridization with genic and repetitive probes revealed that in S. diclinis a reciprocal translocation has occurred between the ancestral Y chromosome and an autosome, resulting in chromosomes designated Y1 and Y2. Both Y1 and Y2 chromosomes are male specific. Y1 pairs with the X chromosome and with the autosome (the neo-X), which cosegregates with X. Y2 pairs only with the neo-X, forming a chain X-Y1-neo-X-Y2 in male meiosis. Despite very recent formation of the neo-sex chromosomes in S. diclinis, they are present in all surveyed individuals throughout the species range. Evolution of neo-sex chromosomes may be the cause of partial reproductive isolation of this species and could have been the isolating mechanism that drove speciation of S. diclinis.
The Role of Environmental Factors in Determining Early Survival and Invasion Success of Exotic Brown Trout
Authors: Wood Jeremiah , Budy Phaedra
Published: May 2009

Due to significant threats to native species posed by nonnative fishes, it is important to understand how species life history strategies interact with environmental conditions to explain the outcome of nonnative fish invasions. Brown troutSalmo truttaare prolific invaders but often exhibit upstream distributional limits in streams of the intermountain western United States. We used redd counts, embryo survival experiments, and temperature modeling to identify limits to brown trout invasion. Brown trout spawned later than previously reported and established spawning areas in high‐elevation stream reaches (1,983‐m elevation), where adult recruitment is typically very low. While embryo survival was lower in high‐elevation, cooler‐water areas, these harsh overwinter conditions did not necessarily preclude hatching success (≥36%). However, model predictions based on winter temperature data indicate that during most years, brown trout fry probably would fail to emerge from the gravel before the onset of peak spring flooding in these high‐elevation reaches, suggesting that high spring flows could limit invasion success. A better understanding of mechanistic limits to invasion success across multiple life stages is crucial to predicting the future expansion of exotic fish species.
Effects of Electroshock on Cyprinid Embryos: Implications for Threatened and Endangered Fishes
Authors: Bohl Russell J. , Henry Theodore B. , Strange Richard J. , Rakes Patrick L.
Published: May 2009

The purpose of this study was to evaluate the effects of electroshock on survival to hatching in embryos of Cyprinidae, which includes numerous fish species designated as threatened or endangered under the U.S. Endangered Species Act. Embryos of three cyprinids were exposed for 20 s to a homogeneous electric field (DC or 60‐Hz pulsed DC [PDC], 3‐ms pulse width) at voltage gradients similar to those used during electrofishing. Exposure occurred only once and was at a specific stage of development. Zebrafish Danio rerio were electroshocked at numerous stages of embryonic development, and the most sensitive developmental stage was determined and used to guide subsequent experiments. Embryos of two minnows native to the southeast United States, the spotfin chub Erimonax monachus and whitetail shiner Cyprinella galactura, were exposed to a range of DC (3‐15 V/cm) and 60‐Hz PDC (8‐15 V/cm) voltage gradients, and survival to hatching was evaluated. Additionally, the potential for electrofishing to induce premature hatching in late‐stage cyprinid embryos was investigated by exposing eyed spotfin chub embryos to 8‐V/cm DC electroshock. Embryos were most vulnerable to electroshock‐induced mortality early in development, particularly near epiboly, and DC was more harmful than 60‐Hz PDC. At older developmental stages, embryos were less vulnerable to electroshock‐induced mortality, although premature hatching was induced in some older developmental stages of electroshocked spotfin chub embryos. Whitetail shiner embryos were more vulnerable (lethal voltage gradient predicted to induce 50% mortality [LV50], 5 V/cm) to electroshock‐induced mortality than were spotfin chub embryos (LV50, 6 V/cm). Results indicate that cyprinid embryos can be killed by DC electroshock at electric field intensities commonly generated by electrofishing equipment, and electrofishing near spawning grounds of threatened or endangered cyprinids should be avoided when embryos are present.
Finite-element modelling of laterally loaded piles in clay
Authors: Ahmadi M. M. , Ahmari S.
Published: May 2009

A three-dimensional finite-element procedure is used to analyse laterally loaded piles in clay. A strain-hardening von Mises constitutive law is used in the analyses. Two field-measured full-scale case studies, one in soft clay and the other one in stiff clay, are investigated by the constructed finite-element model. In order to study soil anisotropy and soil mass secondary structure, the real shear strength and elastic modulus are back-calculated by fitting the pile head load–deflection curve to the field results. Comparing back-calculated shear strength values with the measured ones indicates high anisotropy effect in stiff clay. In order to verify the model validity, the maximum occurred moment and moment distribution are compared with the field results. The comparison shows satisfactory correspondence. Finally, the p–y curves are extracted from the finite-element model and compared with the two p–y sets proposed by Matlock and Wu et al. The comparison shows good agreement with hyperbolic curves for the initial portion and with those proposed by Matlock for the ultimate portion.
Species richness and occupancy estimation in communities subject to temporary emigration
Authors: Kéry Marc , Royle J. Andrew , Plattner Matthias , Dorazio Robert M.
Published: May 2009

Species richness is the most common biodiversity metric, although typically some species remain unobserved. Therefore, estimates of species richness and related quantities should account for imperfect detectability. Community dynamics can often be represented as superposition of species‐specific phenologies (e.g., in taxa with well‐defined flight [insects], activity [rodents], or vegetation periods [plants]). We develop a model for such predictably open communities wherein species richness is expressed as the sum over observed and unobserved species of estimated species‐specific and site‐specific occurrence indicators and where seasonal occurrence is modeled as a species‐specific function of time. Our model is a multispecies extension of a multistate model with one unobservable state and represents a parsimonious way of dealing with a widespread form of “temporary emigration.” For illustration we use Swiss butterfly monitoring data collected under a robust design (RD); species were recorded on 13 transects during two secondary periods within ≤7 primary sampling periods. We compare estimates with those under a variation of the model applied to standard data, where secondary samples are pooled. The latter model yielded unrealistically high estimates of total community size of 274 species. In contrast, estimates were similar under models applied to RD data with constant (122) or seasonally varying (126) detectability for each species, but the former was more parsimonious and therefore used for inference. Per transect, 6–44 (mean 21.1) species were detected. Species richness estimates averaged 29.3; therefore only 71% (range 32–92%) of all species present were ever detected. In any primary period, 0.4–5.6 species present were overlooked. Detectability varied by species and averaged 0.88 per primary sampling period. Our modeling framework is extremely flexible; extensions such as covariates for the occurrence or detectability of individual species are easy. It should be useful for communities with a predictable form of temporary emigration where rigorous estimation of community metrics has proved challenging so far.
Arbuscular mycorrhizal fungi ameliorate temperature stress in thermophilic plants
Authors: Bunn Rebecca , Lekberg Ylva , Zabinski Catherine
Published: May 2009

Biotic interactions can affect the distribution of species across environmental gradients, and as air and soil temperatures increase, plant community response may depend on interactions with symbionts. We measured the effect of elevated soil temperatures on mycorrhizal function and on the response of both plant and fungal symbionts, using fungal inoculum isolated from either high‐temperature thermal or nonthermal grassland soils. Our source for thermal soils was Yellowstone National Park, USA, where plants experience rooting zone temperatures of 45°C or more. In the greenhouse, we grew three plant species (Dichanthelium lanuginosum, Agrostis scabra, and Mimulus guttatus) with three arbuscular mycorrhizal fungal (AMF) treatments (no AMF, nonthermal AMF, thermal AMF) and two soil temperatures (ambient, elevated). Biomass of the facultative thermal plants Agrostis scabra and Mimulus guttatus decreased by 50% in elevated‐temperature soils, and AMF had no effect on measured plant traits. In contrast, the biomass and total root length of the obligate thermal plant Dichanthelium lanuginosum were greater at elevated soil temperatures, but only when mycorrhizal. Both mycorrhizal colonization levels and length of extraradical hyphae (ERH) increased with soil temperature across all host species. The source of the AMF inoculum, on the other hand, did not affect colonization level, ERH length, host plant biomass, or flowering for all host species in either temperature treatment, suggesting that AMF from thermal soils are not specifically adapted to higher temperatures. In the field we collected soil cores to measure in situ depth distributions of D. lanuginosum roots and ERH, and to determine which AMF species were active in plants growing in thermal soils. Roots were limited to soils with an average temperature ≤30°C, while ERH existed in the hottest soils we sampled, averaging 35°C. Molecular analyses of roots indicated that thermal AMF communities were composed of both generalist and possibly unique fungal species. The increase in host plant allocation to AMF, apparent lack of temperature adaptation by AMF, and differential host response to AMF suggest that AMF could be significant drivers of plant community response to increased soil temperature associated with global change.
The use of sighting records to infer species extinctions: an evaluation of different methods
Authors: Rivadeneira Marcelo M. , Hunt Gene , Roy Kaustuv
Published: May 2009

In the absence of long‐term monitoring data, inferences about extinctions of species and populations are generally based on past observations about the presence of a particular species at specified places and times (sightings). Several methods have been developed to estimate the probability and timing of extinctions from records of such sightings, but they differ in their computational complexity and assumptions about the nature of the sighting record. Here we use simulations to evaluate the performance of seven methods proposed to estimate the upper confidence limit on extinction times under different extinction and sampling scenarios. Our results show that the ability of existing methods to correctly estimate the timing of extinctions varies with the type of extinction (sudden vs. gradual) and the nature of sampling effort over time. When the probability of sampling a species declines over time, many of the methods perform poorly. On the other hand, the simulation results also suggest that as long as the choice of the method is determined by the nature of the underlying sighting data, existing methods should provide reliable inferences about the timing of past extinctions.
Environmental variation in ecological communities and inferences from single‐species data
Authors: Abbott Karen C. , Ripa Jörgen , Ives Anthony R.
Published: May 2009

Data are often collected for a single species within an ecological community, so quantitative tools for drawing inferences about the unobserved portions of the community from single‐species data are valuable. In this paper, we present and examine a method for estimating community dimension (the number of strongly interacting species or groups) from time series data on a single species. The dynamics of one species can be strongly affected by environmental stochasticity acting not only on itself, but also on other species with which it interacts. By fully accounting for the effects of stochasticity on populations embedded in a community, our approach gives better estimates of community dimension than commonly used methods. Using a combination of time series data and simulations, we show that failing to properly account for stochasticity when attempting to relate population dynamics to attributes of the community can give misleading information about community dimension.
Locally adapted social parasite affects density, social structure, and life history of its ant hosts
Authors: Foitzik Susanne , Achenbach Alexandra , Brandt Miriam
Published: May 2009

Selection and adaptation are important processes in the coevolution between parasites and their hosts. The slave‐making antProtomognathus americanus, an obligate ant social parasite, has previously been shown to evolve morphological, behavioral, and chemical adaptations in the coevolutionary arms race with itsTemnothoraxhosts. Yet empirical studies have given variable results on the strength of the selection pressure this parasite exerts on its host populations. In this study, we directly investigated the pressure exerted byP. americanusand the reactions of the main host species,T. longispinosus,in two ant communities by manipulating parasite density in the field over several years. In addition, a cross‐fostering design with the exchange of parasites between host populations allowed us to investigate local adaptation of parasite or host. We demonstrate a severe impact of the social parasite on the two host populations in West Virginia and New York, but also variation in host reactions between sites, as expected by the geographic mosaic theory of coevolution. Host density decreased at the West Virginia site with the presence of local slave‐makers, whereas at the ecologically favorable New York site, density was unaffected. Nevertheless, social organization, colony size, and investment patterns of these host colonies at this site changed in response to our parasite manipulation. The release ofP. americanuscolonies led to a reduction in the number of resident queens and workers, an increase in intranest relatedness, and lower productivity, but also a higher investment in reproductives. In West Virginia, colony demography did not change, but raiding activity by New York slave‐makers caused different investment patterns of host colonies. In addition, the cross‐fostering element revealed local adaptation of the parasiteP. americanus: slave‐making colonies fared better in their sympatric host population, as they contained more slave‐making ant workers and slaves at the end of our 27‐month experiment.
Prairie forb response to timing of vole herbivory
Authors: Sullivan Amy T. , Howe Henry F.
Published: May 2009

The timing of herbivory can be an important factor in the strength and direction of plant response to herbivore damage. To determine the effect of vole herbivory timing within a growing season on tallgrass prairie forbs, we used individual plant enclosures to limit vole access to three species, Desmanthus illinoensis, Echinacea purpurea, and Heliopsis helianthoides, in an experimental restoration in northern Illinois, USA. As part of a long‐term experiment, we implemented five vole access treatments in 2003: (1) vole access for the entire growing season, (2) early‐season access, (3) mid‐season access, (4) late‐season access, and (5) no vole access. We protected all plants from herbivory in the following growing season (2004) to test whether the effects of herbivory in one growing season carried over to the next. We also tested how restoration planting design, including seeding time (June or December) and density (35 or 350 seeds/m2 of each species) affected patterns of herbivory and plant recovery.

Vole access for the entire growing season was most detrimental for the growth and reproduction of all three species. In contrast, vole access for a portion of the growing season had different effects on the three species: Desmanthus growth and reproduction was negatively affected by early‐season access, Echinacea reproductive output was reduced by late‐season access, and Heliopsis was not affected by early‐, mid‐, or late‐season vole access. Negative effects of continual vole access carried over to the following growing season for Desmanthus and Heliopsis, but not for Echinacea. Effects of herbivory did not carry over to the next season for Echinacea and Heliopsis when plants were accessible to voles for only part of the growing season. In contrast, Desmanthus plants exposed to early‐season herbivory in one year continued to produce fewer seeds per plant after being protected from vole herbivory for a growing season.

Planting density and planting season had mixed effects. Echinacea and Desmanthus were larger in plots planted in June, showing that restoration design continued to affect plant population dynamics seven years after seeding. However, there was no interaction between plant response to vole herbivory and restoration design.
Summer dietary nitrogen availability as a potential bottom‐up constraint on moose in south‐central Alaska
Authors: McArt Scott H. , Spalinger Donald E. , Collins William B. , Schoen Erik R. , Stevenson Timothy , Bucho Michele
Published: May 2009

Recent studies suggest that the growth and fecundity of northern ungulates may be coupled to their summer nutrition. Here, we compare summer dietary nitrogen availability of the five major browse plants (comprising ∼79% of the diet) of moose (Alces alces) in Denali National Park and Nelchina Basin, Alaska, USA. In recent years the productivity of Denali moose has been significantly higher than that of Nelchina moose, prompting this comparison. We examined the phenological progression of leaf nitrogen concentration, tannin–protein precipitation capacity, and digestible protein over three summers in both regions. We then modeled the potential nutritional consequences for a cow moose consuming representative diets on each range, predicting both net protein intake (NPI) and lean body mass accumulation each year. We found that leaf nitrogen and digestible protein decreased, while tannin–protein precipitation capacity increased throughout the summer for all forages. There was 23% more digestible protein in Denali leaves than Nelchina leaves on average, and this difference was significant in all three years. Tannins accounted for a large (mean = 46%) reduction in protein availability, suggesting a key role of these secondary compounds in the nitrogen balance of moose in these regions. Finally, our NPI model predicted that Denali cows were in positive protein balance 17 days longer than Nelchina cows and accumulated 18 kg more lean body mass over the summer, on average. We conclude that summer dietary nitrogen availability may act as a nutritional constraint on moose and suggest that more emphasis be placed on elucidating its role in population dynamics and conservation of northern ungulates.
An Examination of the Effects of Auditor Rank on Pre-Negotiation Judgments
Authors: Trotman Ken T. , Wright Arnold M. , Wright Sally
Published: May 2009

SUMMARY: Auditors often encounter contentious accounting and reporting issues that require resolution with the client. The purpose of the current study is to examine the impact of auditor rank on pre-negotiation judgments. To address these issues, 25 managers and 18 partners examine a rich experimental case in which they are asked to consider their position and that of the client on a difficult inventory write-down situation. The results indicate that partners take a harder stand than managers in calling for a higher initial proposed write-down, minimum write-down, and expected write-down. Also, partners' estimates of the maximum write-down the client is willing to accept are greater than managers' estimates. Finally, partners indicated a smaller difference between their initial write-down and the estimated amount that would be recorded, as well as a larger difference between the estimated amount that would be recorded and the minimum acceptable write-down, than did managers. Contrary to expectations, there were no differences in the level of persuasion knowledge between partners and managers.
The Revised Model Tax Curriculum
Authors: Dennis-Escoffier Shirley , Kern Beth B. , Rhoades-Catanach Shelley C.
Published: May 2009

ABSTRACT: The American Institute of Certified Public Accountants (AICPA) first developed the Model Tax Curriculum (MTC) in 1996 and modified it in 1999. Subsequent changes in the accounting profession and education caused a reexamination of the MTC resulting in a complete revision in 2007. The revised MTC is learning outcome-based and views the accounting curriculum in its entirety. The revised MTC includes a detailed matrix relating its proposed learning outcomes to the AICPA core competencies and tax technical topics commonly included in tax curricula. The matrix offers accounting faculty one example of an approach to be used in achieving the MTC learning outcomes. This approach can serve as a useful starting point to faculty in formulating and documenting their own approaches to developing student competencies that achieve the revised MTC learning objectives. This paper details the development of the MTC and provides an overview of the revised MTC. It also offers pedagogical suggestions helpful for implementing the MTC.
Performance Analysis of the SIFT Operator for Automatic Feature Extraction and Matching in Photogrammetric Applications
Authors: Lingua Andrea , Marenchino Davide , Nex Francesco
Published: May 2009

In the photogrammetry field, interest in region detectors, which are widely used in Computer Vision, is quickly increasing due to the availability of new techniques. Images acquired by Mobile Mapping Technology, Oblique Photogrammetric Cameras or Unmanned Aerial Vehicles do not observe normal acquisition conditions. Feature extraction and matching techniques, which are traditionally used in photogrammetry, are usually inefficient for these applications as they are unable to provide reliable results under extreme geometrical conditions (convergent taking geometry, strong affine transformations, etc.) and for bad-textured images. A performance analysis of the SIFT technique in aerial and close-range photogrammetric applications is presented in this paper. The goal is to establish the suitability of the SIFT technique for automatic tie point extraction and approximate DSM (Digital Surface Model) generation. First, the performances of the SIFT operator have been compared with those provided by feature extraction and matching techniques used in photogrammetry. All these techniques have been implemented by the authors and validated on aerial and terrestrial images. Moreover, an auto-adaptive version of the SIFT operator has been developed, in order to improve the performances of the SIFT detector in relation to the texture of the images. The Auto-Adaptive SIFT operator (A2 SIFT) has been validated on several aerial images, with particular attention to large scale aerial images acquired using mini-UAV systems.