Proximate and Ultimate Causation of Egg Size and the "Third-Chick Disadvantage" in the Western Gull

This is the publisher's version, also available electronically from http://www.jstor.org/stable/4087093?seq=1#page_scan_tab_contents.No abstract is available for this item

Patterns of Aggression in Gulls: Asymmetries and Tactics in Different Social Categories

During contests in Western Gulls, Larus occidentalis, we examined patterns of aggression in relation to sex, age class, and territorial status. Data were collected on agonistic contests during parts of three reproductive seasons on Southeast Farallon Island. This colony has dense nesting territories and appears to be near saturation, making breeding space a limiting and valuable resource. Established, territory-holding male gulls were able to defeat nearly all opponents. The exceptions were a few unestablished adult males early in the reproductive period that appeared to be equal, or superior to, established males in fighting ability and persistence. Established females were able to defend their territories against territory-holding neighbors, immature gulls, and adult female intruders, but often were forced to retreat by unestablished male intruders. Both immature and unestablished adult intruders more readily challenged an established female than an established male. The value of breeding territories, the primary contested resource, appeared to increase throughout the reproductive period as established birds became increasingly inclined to escalate encounters after eggs were laid, and even more inclined to escalate after chicks appeared. In contrast, unestablished adults became less common and, when present, less inclined to escalate as the season progressed

Hybridization and Male Parental Investment in Birds

Hybridization within genera occurs more frequently in avian families and subfamilies where there is considerable male parental investment, less frequently in families with moderate levels of male parental investment, and rarely in lineages where males contribute only genetic material to their offspring. In addition, genera that show considerable male parental investment are typically less speciose than genera where there is reduced male parental investment. Species showing high levels of male parental investment, however, typically have more subspecies, indicating that local adaptation evolves in these groups, but reproductive isolation does not evolve. Some hybrid matings appear to involve females of one species showing an apparent preference for mating with larger or dominant males, even if these males are heterospecific (e.g., black and mallard ducks). Similar patterns occur in fishes, amphibians, and mammals, the other three vertebrate lineages that show extensive parental care. Hybridization in birds may be an evolutionary mechanism that allows increased genetic diversity and adaptability under changing environmental conditions, particularly environments disturbed by humans. It is also possible that new forms (incipient species) may arise through hybridization that are better adapted to disturbed environments than either parental species

Overtourism: A literature review to assess implications and future perspectives

Overtourism is an emerging concept facing the world's main tourist destinations. The growth that tourism has undergone in recent decades is of two different types. On the one hand, the development of new technologies and the creation of low-cost airline carriers have increased tourism levels, leading to growth even in emerging economies. On the other hand, uncontrolled demand alongside a concentration of tourism in particular destinations impact negatively both territories and local communities. The problems caused in some destinations by the increasing, ongoing growth in tourism have created the issue of "overtourism," which is assuming an increasing significance in the literature. This paper contributes to the literature by providing an exploratory study with which to better understand the origins of overtourism, its implications, and predicted future perspectives in respect to the issue. Examination of the new evidence presented here contributes to the expanding knowledge of particular problems of tourism development

3D FEM and DEM Analyses of Underground Openings in Competent Rock Masses

The paper is aimed at comparing the results of numerical analyses of underground openings in competent rock masses like the Carrara Marble (Italy) by considering a real and well documented case study. More specifically, 3D FEM and DEM analyses were carried out on a rock-mass model interested by two faults and three sets of discontinuities. The geometrical model is representative of deep underground openings where spalling-cracks and rock bursts can occur. PLAXIS 3D and 3DEC were used for the analyses. Intact rock and rock mass characterization of Carrara Marble was inferred from available technical literature. The analysis results were compared in terms of principal stresses and displacements in a number of monitoring points around the opening. The main practical interest is to find out a reliable approach for evaluating the stability of very large openings in a competent rock mass like Carrara marble. For such a purpose, a number of available in-situ stress measurements were used

Intermittency in the large N-limit of a spherical shell model for turbulence

A spherical shell model for turbulence, obtained by coupling $N$ replicas of the Gledzer, Okhitani and Yamada shell model, is considered. Conservation of energy and of an helicity-like invariant is imposed in the inviscid limit. In the $N \to \infty$ limit this model is analytically soluble and is remarkably similar to the random coupling model version of shell dynamics. We have studied numerically the convergence of the scaling exponents toward the value predicted by Kolmogorov theory (K41). We have found that the rate of convergence to the K41 solution is linear in 1/N. The restoring of Kolmogorov law has been related to the behaviour of the probability distribution functions of the instantaneous scaling exponent.Comment: 10 pages, Latex, 3 Postscript figures, to be published on Europhys. Let

Human Apolipoprotein B Transgenic Mice Generated with 207- and 145-Kilobase Pair Bacterial Artificial Chromosomes. Evidence that a distant 5'-element confers appropriate transgene expression in the intestine

We reported previously that ~80-kilobase pair (kb) P1 bacteriophage clones spanning either the human or mouse apoB gene (clones p158 and p649, respectively) confer apoB expression in the liver of transgenic mice, but not in the intestine. We hypothesized that the absence of intestinal expression was due to the fact that these clones lacked a distant DNA element controlling intestinal expression. To test this possibility, transgenic mice were generated with 145- and 207-kb bacterial artificial chromosomes (BACs) that contained the human apoB gene and more extensive 5'- and 3'-flanking sequences. RNase protection, in situ hybridization, immunohistochemical, and genetic complementation studies revealed that the BAC transgenic mice manifested appropriate apoB gene expression in both the intestine and the liver, indicating that both BACs contained the distant intestinal element. To determine whether the regulatory element was located 5' or 3' to the apoB gene, transgenic mice were generated by co-microinjecting embryos with p158 and either the 5'- or 3'-sequences from the 145-kb BAC. Analysis of these mice indicated that the apoB gene's intestinal element is located 5' to the structural gene. Cumulatively, the transgenic mouse studies suggest that the intestinal element is located between -33 and -70 kb 5' to the apoB gene

FLARE: A Framework for the Finite Element Simulation of Electromagnetic Interference on Buried Metallic Pipelines

The functionality of buried metallic pipelines can be compromised by the electrical lines that share the same right-of-way. Given the considerable size of shared corridors, computer simulation is an important tool for performing risk assessment and mitigation design. In this work, we introduce an open-source computational framework for the analysis of electromagnetic interference on large earth-return structures. The developed framework is based on FLARE-an efficient finite element solver developed by the authors in MATLAB((R)). FLARE includes solvers for problems involving static electric and magnetic fields, and DC and time-harmonic AC currents. Quasi-magnetostatic transient problems can be studied through time-marching or-for linear problems-with an efficient inverse-Laplace approach. In this work, we succinctly describe the optimization of time-critical operations in FLARE, as well as the implementation of a transient solver with automatic time-stepping. We validate the numerical results obtained with FLARE via a comparison with the commercial software COMSOL Multiphysics((R)). We then use the validated time-marching analysis results to test the accuracy and efficiency of three numerical inverse-Laplace algorithms. The test problem considered is the assessment of the inductive coupling between a 500 kV transmission line and a metallic pipeline buried in the soil

Esthesioneuroblastoma is not a member of the primitive peripheral neuroectodermal tumour-Ewing’s group

Esthesioneuroblastoma (ENB) is a rare, site-specific, locally aggressive neuronal malignancy so far thought to belong to primitive peripheral neuroectodermal tumour-Ewing's tumour (pPNETs-ETs). Its anatomical location, in addition to morphologic, immunophenotypic and ultrastructural features, suggests its origin in the neuronal or neuroendocrine cells of the olfactory epithelium. However, the cytogenetic and molecular data currently available appear controversial on the presence of the typical translocation t(11;22)(q24;q12) and of trisomy 8, chromosomal changes that characterize the tumours belonging to the pPNETs-ETs. Herein we have analysed five ENB tumour specimens for trisomy 8 by fluorescence in situ hybridization (FISH), for the presence of EWS gene rearrangements by FISH, reverse transcription polymerase chain reaction and Southern blot analyses, as well as for the expression of the Ewing sarcoma-associated MIC2 antigen by immunohistochemistry. Neither EWS/FLI-I, EWS/ERG and EWS/FEV fusion genes nor MIC2 expression were found in any tumour, whereas trisomy 8 was found in one case only. Moreover, DNA from three cases analysed by Southern blot did not show EWS gene rearrangements. Our results support the evidence that ENB is not a member of the pPNETs-ETs. © 1999 Cancer Research Campaig