Environmental effects on Common Snipe winnowing and calling (activity)

Our objective was to clarify the effects of 10 identified variables on snipe activity (winnowing and calling) by demonstrating correlations between the variables and snipe activity. We monitored snipe at 2 study areas in southwestern Montana and northwestern Wyoming at all hours of the day and night during the 1996 and 1997 breeding seasons. We measured 10 variables at established points along transects that were situated through the middle of each study site (8 study sites total). A total of 1200 monitoring periods were conducted throughout the course of this study. Effects of each factor on snipe activity were considered by examining general trends in each factor's graphical representation. Our results identified 6 factors (season, time of day, lunar cycle, solar radiation, wind speed, and temperature) that are associated with snipe activity. Snipe were most active early in the breeding season during 2 twilight periods during the first and last quarters of the lunar cycle. Low solar radiation levels, wind speeds, and temperatures were also most ideal conditions for snipe activity. All 6 factors should be considered when attempting to detect, survey, or estimate snipe populations.     

The cranial endoskeleton of Tiktaalik roseae

Among the morphological changes that occurred during the 'fish-to-tetrapod' transition was a marked reorganization of the cranial endoskeleton. Details of this transition, including the sequence of character acquisition, have not been evident from the fossil record. Here we describe the braincase, palatoquadrate and branchial skeleton of Tiktaalik roseae, the Late Devonian sarcopterygian fish most closely related to tetrapods. Although retaining a primitive configuration in many respects, the cranial endoskeleton of T. roseae shares derived features with tetrapods such as a large basal articulation and a flat, horizontally oriented entopterygoid. Other features in T. roseae, like the short, straight hyomandibula, show morphology intermediate between the condition observed in more primitive fish and that observed in tetrapods. The combination of characters in T. roseae helps to resolve the relative timing of modifications in the cranial endoskeleton. The sequence of modifications suggests changes in head mobility and intracranial kinesis that have ramifications for the origin of vertebrate terrestriality.     

Increased sedimentation rates and grain sizes 2-4 Myr ago due to the influence of climate change on erosion rates

Around the globe, and in a variety of settings including active and inactive mountain belts, increases in sedimentation rates as well as in grain sizes of sediments were recorded at approximately 2-4 Myr ago, implying increased erosion rates. A change in climate represents the only process that is globally synchronous and can potentially account for the widespread increase in erosion and sedimentation, but no single process-like a lowering of sea levels or expanded glaciation-can explain increases in sedimentation in all environments, encompassing continental margins and interiors, and tropical as well as higher latitudes. We suggest that climate affected erosion mainly by the transition from a period of climate stability, in which landscapes had attained equilibrium configurations, to a time of frequent and abrupt changes in temperature, precipitation and vegetation, which prevented fluvial and glacial systems from establishing equilibrium states.     

Chromatin dynamics and the preservation of genetic information

The integrity of the genome is frequently challenged by double-strand breaks in the DNA. Defects in the cellular response to double-strand breaks are a major cause of cancer and other age-related pathologies; therefore, much effort has been directed at understanding the enzymatic mechanisms involved in recognizing, signalling and repairing double-strand breaks. Recent work indicates that chromatin - the fibres into which DNA is packaged with a proteinaceous structural polymer - has an important role in initiating, propagating and terminating this cellular response to DNA damage.     

Histones as tumour suppressor genes

No Abstract. .Received 4 March 2005; received after revision 7 April 2005; accepted 26 April 2005     

Municipal budget forecasting with multivariate ARMA models

In this paper multivariate ARMA models are applied to the problem of forecasting city budget variables. Unlike univariate time-series methods, multivariate models can use relationships among budget variables as well as relationships with economic and demographic indicators. Although available budget series are shorter than what is usually believed necessary for multivariate ARMA modelling, the forecasts seem to be of higher quality than those from univariate models.