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Selected AbstractsInterpreting temporal variation in omnivore foraging ecology via stable isotope modellingFUNCTIONAL ECOLOGY, Issue 4 2009Carolyn M. Kurle Summary 1The use of stable carbon (C) and nitrogen (N) isotopes (,15N and ,13C, respectively) to delineate trophic patterns in wild animals is common in ecology. Their utility as a tool for interpreting temporal change in diet due to seasonality, migration, climate change or species invasion depends upon an understanding of the rates at which stable isotopes incorporate from diet into animal tissues. To best determine the foraging habits of invasive rats on island ecosystems and to illuminate the interpretation of wild omnivore diets in general, I investigated isotope incorporation rates of C and N in fur, liver, kidney, muscle, serum and red blood cells (RBC) from captive rats raised on a diet with low ,15N and ,13C values and switched to a diet with higher ,15N and ,13C values. 2I used the reaction progress variable method (RPVM), a linear fitting procedure, to estimate whether a single or multiple compartment model best described isotope turnover in each tissue. Small sample Akaike Information criterion (AICc) model comparison analysis indicated that 1 compartment nonlinear models best described isotope incorporation rates for liver, RBC, muscle, and fur, whereas 2 compartment nonlinear models were best for serum and kidney. 3I compared isotope incorporation rates using the RPVM versus nonlinear models. There were no differences in estimated isotope retention times between the model types for serum and kidney (except for N turnover in kidney from females). Isotope incorporation took longer when estimated using the nonlinear models for RBC, muscle, and fur, but was shorter for liver tissue. 4There were no statistical differences between sexes in the isotope incorporation rates. I also found that N and C isotope incorporation rates were decoupled for liver, with C incorporating into liver tissue faster than N. 5The data demonstrate the utility of analysing isotope ratios of multiple tissues from a single animal when estimating temporal variation in mammalian foraging ecology. [source] Psychosocial effects in long-term head and neck cancer survivorsHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 4 2005Richard L. Holloway PhD Abstract Background. To identify and rate the importance of several psychosocial and physiologic influences on quality of life (QOL) among a cohort of 5-year head and neck cancer survivors, we conducted a cross-sectional study of a convenience sample that used both questionnaires and physiologic evaluations. Methods. QOL was assessed by the Functional Assessment of Cancer Therapy (FACT) and the FACT Head and Neck additional concerns (FACT-H&N) questionnaires. Psychosocial characteristics (or risk factors) potentially influencing QOL were measured by the Millon Behavioral Health Inventory (MBHI) and the Social Support Questionnaire (SSQSR). Physiologic risk factors were measured in examinations that included shoulder and neck range of motion, whole and stimulated saliva measurements, and oropharyngeal swallowing efficiency. We evaluated the association of selected QOL measures with three groups of potential risk factors: psychosocial factors, consisting of selected MBHI and SSQSR scales; physiologic factors, consisting of selected physical ability measures; and a combination of psychosocial/physiologic factors. Results. The entire study population of 105 subjects completed the FACT and FACT-H&N questionnaires; 86 of these completed the physiologic tests as well. Combined psychosocial/physiologic models best predicted all QOL measures considered. Psychosocial models alone, compared with physiologic models alone, better predicted FACT physical and social/family well-being measures. Physiologic models alone, compared with psychosocial models alone, better predicted FACT-H&N additional concerns measures. Premorbid pessimism (MBHI) was consistently the best predictor of QOL measures. Conclusions. Both psychosocial and physiologic factors influence QOL in patients with head and neck cancer, but many QOL measures are most strongly influenced by psychosocial considerations. Physicians and surgeons caring for long-term head and neck cancer survivors should be cognizant of the importance of psychosocial risk factors in the QOL of their patients. © 2005 Wiley Periodicals, Inc. Head Neck27: XXX,XXX, 2005 [source] Modelling of air drying of fresh and blanched sweet potato slicesINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2010Kolawole O. Falade Summary Effects of blanching, drying temperatures (50,80 °C) and thickness (5, 10 and 15 mm) on drying characteristics of sweet potato slices were investigated. Lewis, Henderson and Pabis, Modified Page and Page models were tested with the drying patterns. Page and Modified Page models best described the drying curves. Moisture ratio vs. drying time profiles of the models showed high correlation coefficient (R2 = 0.9864,0.9967), and low root mean squared error (RMSE = 0.0018,0.0130) and chi-squared (,2 = 3.446 × 10,6,1.03 × 10,2). Drying of sweet potato was predominantly in the falling rate period. The temperature dependence of the diffusion coefficient (Deff) was described by Arrhenius relationship. Deff increased with increasing thickness and air temperature. Deff of fresh and blanched sweet potato slices varied between 6.36 × 10,11,1.78 × 10,9 and 1.25 × 10,10,9.75 × 10,9 m2 s,1, respectively. Activation energy for moisture diffusion of the slices ranged between 11.1 and 30.4 kJ mol,1. [source] Mathematical modeling of appendicular bone growth in glaucous-winged gullsJOURNAL OF MORPHOLOGY, Issue 1 2009James L. Hayward Abstract Development of locomotor activity is crucial in tetrapods. In birds, this development leads to different functions for hindlimbs and forelimbs. The emergence of walking and flying as very different complex behavior patterns only weeks after hatching provides an interesting case study in animal development. We measured the diaphyseal lengths and midshaft diameters of three wing bones (humerus, ulna, and carpometacarpus) and three leg bones (femur, tibiotarsus, and tarsometatarsus) of 79 juvenile (ages 0,42 days) and 13 adult glaucous-winged gulls (Larus glaucescens), a semiprecocial species. From a suite of nine alternative mathematical models, we used information-theoretic criteria to determine the best model(s) for length and diameter of each bone as a function of age; that is, we determined the model(s) that obtained the best tradeoff between the minimized sum of squared residuals and the number of parameters used to fit the model. The Janoschek and Holling III models best described bone growth, with at least one of these models yielding an R2 , 0.94 for every dimension except tarsometatarsus diameter (R2 = 0.87). We used the best growth models to construct accurate allometric comparisons of the bones. Early maximal absolute growth rates characterize the humerus, femur, and tarsometatarsus, bones that assume adult-type support functions relatively early during juvenile development. Leg bone lengths exhibit more rapid but less sustained relative growth than wing bone lengths. Wing bone diameters are initially smaller than leg bone diameters, although this relationship is reversed by fledging. Wing bones and the femur approach adult length by fledging but continue to increase in diameter past fledging; the tibiotarsus and tarsometatarsus approach both adult length and diameter by fledging. In short, the pattern of bone growth in this semiprecocial species reflects the changing behavioral needs of the developing organism. J. Morphol., 2009. © 2008 Wiley-Liss, Inc. [source] An evaluation of mathematical models for predicting skin permeabilityJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2008Guoping Lian Abstract A number of mathematical models have been proposed for predicting skin permeability, mostly empirical and very few are deterministic. Early empirical models use simple lipophilicity parameters. The recent trend is to use more complicated molecular structure descriptors. There has been much debate on which models best predict skin permeability. This article evaluates various mathematical models using a comprehensive experimental dataset of skin permeability for 124 chemical compounds compiled from various sources. Of the seven models compared, the deterministic model of Mitragotri gives the best prediction. The simple quantitative structure permeability relationships (QSPR) model of Potts and Guy gives the second best prediction. The two models have many features in common. Both assume the lipid matrix as the pathway of transdermal permeation. Both use octanol,water partition coefficient and molecular size. Even the mathematical formulae are similar. All other empirical QSPR models that use more complicated molecular structure descriptors fail to provide satisfactory prediction. The molecular structure descriptors in the more complicated QSPR models are empirically related to skin permeation. The mechanism on how these descriptors affect transdermal permeation is not clear. Mathematically it is an ill-defined approach to use many colinearly related parameters rather than fewer independent parameters in multi-linear regression. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:584,598, 2008 [source] Using phylochronology to reveal cryptic population histories: review and synthesis of 29 ancient DNA studiesMOLECULAR ECOLOGY, Issue 7 2009UMA RAMAKRISHNAN Abstract The evolutionary history of a population involves changes in size, movements and selection pressures through time. Reconstruction of population history based on modern genetic data tends to be averaged over time or to be biased by generally reflecting only recent or extreme events, leaving many population historic processes undetected. Temporal genetic data present opportunities to reveal more complex population histories and provide important insights into what processes have influenced modern genetic diversity. Here we provide a synopsis of methods available for the analysis of ancient genetic data. We review 29 ancient DNA studies, summarizing the analytical methods and general conclusions for each study. Using the serial coalescent and a model-testing approach, we then re-analyse data from two species represented by these data sets in a common interpretive framework. Our analyses show that phylochronologic data can reveal more about population history than modern data alone, thus revealing ,cryptic' population processes, and enable us to determine whether simple or complex models best explain the data. Our re-analyses point to the need for novel methods that consider gene flow, multiple populations and population size in reconstruction of population history. We conclude that population genetic samples over large temporal and geographical scales, when analysed using more complex models and the serial coalescent, are critical to understand past population dynamics and provide important tools for reconstructing the evolutionary process. [source] | |||||||||||||