Negative ion electrospray mass spectra of caerulein peptides: an aid to structural determination

MS/MS data derived from the [M-H](-) ions of desulfated caerulein peptides provide (i) sequencing information from a combination of alpha, beta and gamma backbone cleavages, and (ii) identification of specific amino acid side chains by side-chain cleavages [e.g. Ser (-CH2O), Thr (-CH3CHO) and Asp (-H2O)] (fragmentations having no counterparts in positive ion spectra). In addition, delta and/or gamma backbone cleavage ions from Asp residues identify the position of these residues in the peptide. In contrast, neither delta nor gamma cleavage ions are observed from either the Gln2 residue nor from Phe residues. Full structural information can be obtained from a consideration of the positive and negative ion MS/MS data in concert. Copyright (C) 2002 John Wiley Sons, Ltd.

Monitoring green turtles (Chelonia mydas) at a coastal foraging area in Baja California, Mexico: multiple indices to describe population status

From June 1995 to August 2002 we assessed green turtle (Chelonia mydas) population structure and survival, and identified human impact, at Bahia de los Angeles, a large bay that was once the site of the greatest sea turtle harvest rates in the Gulf of California, Mexico. Turtles were captured live with entanglement nets and mortality was quantified through stranding surveys and flipper tag recoveries. A total of 14,820 netting hours (617.5 d) resulted in 255 captures of 200 green turtles. Straight-carapace length and mass ranged from 46.0-100.0 cm (mean = 74.3 +/- 0.7 cm) and 14.5-145.0 kg (mean = 61.5 +/- 1.7 kg), respectively. The size-frequency distribution remained stable during all years and among all capture locations. Anthropogenic-derived injuries ranging from missing flippers to boat propeller scars were present in 4% of captured turtles. Remains of 18 turtles were found at dumpsites, nine stranded turtles were encountered in the study area, and flipper tags from seven turtles were recovered. Survival was estimated at 0.58 for juveniles and 0.97 for adults using a joint live-recapture and dead-recovery model (Burnham model). Low survival among juveniles, declining annual catch per unit effort, and the presence of butchered carcasses indicated human activities continue to impact green turtles at this foraging area.

A theoretical exploration of catchment-scale sediment delivery

This paper proposes a theoretical explanation of the variations of the sediment delivery ratio (SDR) versus catchment area relationships and the complex patterns in the behavior of sediment transfer processes at catchment scale. Taking into account the effects of erosion source types, deposition, and hydrological controls, we propose a simple conceptual model that consists of two linear stores arranged in series: a hillslope store that addresses transport to the nearest streams and a channel store that addresses sediment routing in the channel network. The model identifies four dimensionless scaling factors, which enable us to analyze a variety of effects on SDR estimation, including (1) interacting processes of erosion sources and deposition, (2) different temporal averaging windows, and (3) catchment runoff response. We show that the interactions between storm duration and hillslope/channel travel times are the major controls of peak-value-based sediment delivery and its spatial variations. The interplay between depositional timescales and the travel/residence times determines the spatial variations of total-volume-based SDR. In practical terms this parsimonious, minimal complexity model could provide a sound physical basis for diagnosing catchment to catchment variability of sediment transport if the proposed scaling factors can be quantified using climatic and catchment properties.

Why children and adults sometimes (but not always) compute implicatures

Noveck (2001) argued that children even as old as 11 do not reliably endorse a scalar interpretation of weak scalar terms (some, might, or) (cf. Braine & Rumain, 1981; Smith, 1980). More recent studies suggest, however, that children's apparent failures may depend on the experimental demands (Papafragou & Musolino, 2003). Although previous studies involved children of different ages as well as different tasks, and are thus not directly comparable, nevertheless a common finding is that children do not seem to derive scalar implicatures to the same extent as adults do. The present article describes a series of experiments that were conducted with Italian speaking subjects (children and adults), focusing mainly on the scalar term some. Our goal was to carefully examine the specific conditions that allow the computation of implicatures by children. In so doing, we demonstrate that children as young as 7 (the youngest age of the children who participated in the Noveck study) are able to compute implicatures in experimental conditions that properly satisfy certain contextual prerequisites for deriving such implicatures. We also present further results that have general consequences for the research methodology employed in this area of study. Our research indicates that certain tasks mask children's understanding of scalar terms, not only including the task used by Noveck, but also tasks that employ certain explicit instructions, such as the training task used by Papafragou & Musolino (2003). Our findings indicate further that, although explicit training apparently improves children's ability to draw implicatures, children nevertheless fail to achieve adult levels of performance for most scalar terms even in such tasks, and that the effects of instruction do not last beyond the training session itself for most children. Another relevant finding of the present study is that some of the manipulations of the experimental context have an effect on all subjects, whereas others produce effects on just a subset of children. Individual differences of this kind may have been concealed in previous research because performance by individual subjects was not reported. Our general conclusions are that even young children (7-year olds) have the prerequisites for deriving scalar implicatures, although these abilities are revealed only when the conversational background is natural.

Relationship between work performance and personality traits in Hong Kong organizational settings

Four hundred and thirty-seven employees from four Hong Kong organizations completed the Traditional Chinese versions of the Fifteen Factor Personality Questionnaire Plus (15FQ+) and the Cross-Cultural Personality Assessment Inventory (CPAI-2) (indigenous scales) and provided objective and memory-based recent performance appraisal scores. A number of significant bivariate correlations were found between personality and performance scores. Hierarchical multiple regression analyses revealed that a number of the scales from the 15FQ+ contributed to significantly predicting four of the performance competency dimensions, but that the CPAI-2 indigenous scales contributed no incremental validity in performance prediction over and above the 15FQ+. Results are discussed in the light of previous research and a call made for continued research to further develop and increase the reliability of the Chinese instruments used in the study and to enable generalization of the findings with confidence.