Analysis of multiple aspects of a repeated signal: power and rate of rapping during shell fights in hermit crabs

Repeated activities used by animals during contests are assumed to act as signals advertising the quality of the sender. However, their exact functions are not well understood and observations fit only a limited set of the predictions made by models of signaling systems. Experimental studies of contest behavior tend to focus on analysis of the rate of signaling, but individual performances may also vary in magnitude. Both of these features can vary between outcomes and within contests. We examined changes in the rate and power of shell rapping during shell fights in hermit crabs. We show that both rate and power decline during the course of the encounter and that the duration of pauses between bouts of shell rapping increases with an index of the total effort put into each bout. This supports the idea that the vigor of shell rapping is regulated by fatigue and could therefore act as a signal of stamina. By examining different interacting components of this complex activity, we gain greater insight into its function than would be achieved by investigating a single aspect in isolation.

Electron-impact excitation of Cr II A theoretical calculation of collision and effective collision strengths for forbidden transitions

Context. Absorption or emission lines of Cr II are observed in a wide variety of astrophysical spectra and accurate atomic data are urgently needed to interpret these lines. Many of these data are impossible to measure experimentally and a full theoretical treatment is the only means by which these data can be obtained.

Aims. In this paper, we present collision strengths and effective collision strengths for electron-impact excitation of Cr II for forbidden transitions among the lowest-lying 74 fine-structure levels. Effective collision strengths have been computed for 18 individual electron temperatures of astrophysical importance, ranging from 2000-100 000 K.

Methods. The parallel suite of R-matrix packages, RMATRX II, which has recently been extended to allow for the inclusion of relativistic effects, has been used in the present work to compute the collision strengths and effective collision strengths for electron-impact excitation of Cr II. We concentrate in this publication on low-lying forbidden lines among the lowest 74 jj fine-structure levels with configurations 3d(5) and 3d(4)4s, although atomic data has been evaluated for all 39 060 transitions among the 280 jj levels of configurations 3d(5), 3d(4)4s and 3d(4)4p. This work constitutes the largest evaluation ever performed for this ion involving 1932 coupled channels.

Results. Collision and effective collision strengths are presented for all transitions among the lowest 74 J pi states of Cr II and comparisons made with the work of Bautista et al. (2009). While the effective collision strengths agree well for some transitions, significant discrepancies exist for others. We believe that the present atomic data represents the most accurate, most sophisticated and most complete data set for electron-impact excitation of Cr II and we would recommend them to astrophysicists and plasma physicists in their application work. We would expect that the effective collision strengths presented for the important low-lying forbidden lines are accurate to within 15%.

Modelling the effect of water immersion thermal processing on polyacetylene levels and instrumental colour of carrot disks

C₁₇ polyacetylenes are a group of bioactive compounds present in carrots which have recently gained scientific attention due to their cytotoxicity against cancer cells. In common with many bioactive compounds, their levels may be influenced by thermal processes, such as boiling or water immersion. This study investigated the effect of a number of water immersion time/temperature combinations on concentrations of these compounds and attempted to model the changes. Carrot samples were thermally treated by heating in water at temperatures from 50–100 °C and holding times of 2–60 min. Following heating, levels of falcarinol (FaOH), falcarindiol (FaDOH), falcarindiol-3-acetate (FaDOAc) and Hunter colour parameters (L^*, a^*, b^*) were determined. FaOH, FaDOH, FaDOAc levels were significantly reduced at lower temperatures (50–60 °C). In contrast, samples heated at temperatures from 70–100 °C exhibited higher levels of polyacetylenes (p < 0.05) than did raw unprocessed samples. Regression modelling was used to model the effects of temperature and holding time on the levels of the variables measured. Temperature treatment and holding time were found to significantly affect the polyacetylene content of carrot disks. Predicted models were found to be significant (p < 0.05) with high coefficients of determination (R²).

Tumor Risks and Genotype-Phenotype-Proteotype Analysis in 358 Patients With Germline Mutations in SDHB and SDHD

Succinate dehydrogenase B (SDHB) and D (SDHD) subunit gene mutations predispose to adrenal and extraadrenal pheochromocytomas, head and neck paragangliomas (HNPGL), and other tumor types. We report tumor risks in 358 patients with SDHB (n = 295) and SDHD (n = 63) mutations. Risks of HNPGL and pheochromocytoma in SDHB mutation carriers were 29% and 52%, respectively, at age 60 years and 71% and 29%, respectively, in SDHD mutation carriers. Risks of malignant pheochromocytoma and renal tumors (14% at age 70 years) were higher in SDHB mutation carriers; 55 different mutations (including a novel recurrent exon 1 deletion) were identified. No clear genotype-phenotype correlations were detected for SDHB mutations. However, SDHD mutations predicted to result in loss of expression or a truncated or unstable protein were associated with a significantly increased risk of pheochromocytoma compared to missense mutations that were not predicted to impair protein stability (most such cases had the common p.Pro81Leu mutation). Analysis of the largest cohort of SDHB/D mutation carriers has enhanced estimates of penetrance and tumor risk and supports in silicon protein structure prediction analysis for functional assessment of mutations. The differing effect of the SDHD p.Pro81Leu on HNPGL and pheochromocytoma, risks suggests differing mechanisms of tumorigenesis in SDH-associated HNPGL and pheochromocytoma. Hum Mutat 31:41-51, 2010. (C) 2009 Wiley-Liss, Inc.

Alcohol and the affluence paradox: A secondary analysis exploring the health disparities surrounding adolescent alcohol use and alcohol related harm in adulthood

Several studies have shown social differences in alcohol consumption, and social inequalities of harm related to alcohol use and abuse. However, relationships between the position in the socio-economic spectrum, alcohol use, and alcohol-related health problems are not clear cut. While there is some evidence of social gradients or associations between indicators of deprivation and some adolescence outcomes (e.g. externalising behaviour), the evidence regarding associations between socio-economic status and alcohol-related problems in adolescence is more conflicting. A major problem in studying socio-economic inequalities in adolescent health is related to the paucity of measures of socio-economic status in adolescence that are both conceptually and methodologically sound.
The aims of this study were to investigate socio-economic differences in pathways from onset to establishment of drinking patterns in adolescence, assess the consequences of these pathways in terms of alcohol related harm, and to consider the causal mechanisms that may contribute to socio-economic differences in drinking pathways and outcomes

Energy levels, radiative rates and electron impact excitation rates for transitions in Si XII, Si XIII and Si XIV

In this paper, we report calculations of energy levels, radiative rates and electron impact excitation rates for transitions in Li-like Si XII, He-like Si XIII and H-like Si XIV. The grasp (general-purpose relativistic atomic structure package) is adopted for calculating energy levels and radiative rates, while for determining the collision strengths and subsequently the excitation rates, the Dirac atomic R-matrix code (darc) is used. Oscillator strengths, radiative rates and line strengths are reported for all E1, E2, M1 and M2 transitions among the lowest 24 levels of Si XII, 49 levels of Si XIII and 25 levels of Si XIV, belonging to the n≤5 configurations. Collision strengths have been averaged over a Maxwellian electron velocity distribution and the effective collision strengths so obtained are reported over a wide temperature range below 107 K. Comparisons have been made with similar data obtained from the flexible atomic code (fac) to highlight the importance of resonances, included in calculations from darc, in the determination of effective collision strengths. Discrepancies between the collision strengths from darc and fac, particularly for weak transitions and at low energies, are also discussed. Additionally, lifetimes are listed for all calculated levels of the above three ions, although no measurements are available with which to compare.