The Use of Spider Silk in the Nests of Small Birds, With Particular Reference to the Chaffinch (Fringilla coelebs)

A very wide range of smaller passerine birds employ silk, from spiders and other arthropods, as a nesting material. The nest is an important feature of bird breeding behaviour, success being dependent in part upon the structure of the nest and the timing of construction of the nest. Spiders can spin many different types of silk, with varying properties, but all spider silks are remarkably strong and extensible. In addition, web silk is adhesive and represents a renewable resource. This study has shown that the chaffinch uses spider web and cocoon silk. Cocoon silk attaches lichen to the outside of the nest, and holds together the moss structure. Web silk is used in more general roles, and usually to a lesser extent; it appears to be an all purpose bonding material, attaching a range of materials to the outside of the nest, and binding together other structural materials. Web silk is also used to attach the nest to the twigs of the bush or tree in which it is built. Using scanning electron microscopy, it has not been possible to identify with any certainty the spider families which spin the cocoon silk used, but all web silk found in chaffinch nests appears to belong to the family Amaurobiidae. These webs are spun flat against rough tree bark and on fences etc. , and trap insects by entangling them in extremely fine fibrils. The amount of this silk present at Garscube Estate, on the edge of Glasgow, starts to rise just before the onset of chaffinch nest building. It is proposed that nest-building is not restricted in location by the availability of this common silk-type, but the birds may be prevented from building earlier in the season by a lack of these webs in the environment. However, the use of silk appears to enable them to breed in areas where the sites and materials available for nest-building are not ideal. It may be possible to generalise these findings for the chaffinch to other temperate, and tropical, passerines that employ silk as a nesting material. Compared with chaffinch nests, the extent of silk usage can be far greater, and the number of functions it fulfils far wider, in nests of other birds. The birds may consequently find themselves more restricted in time and place of breeding where the types of silk needed are not in abundance

Long-term Benefits of GM crops: Potential for Diabrotica Suppression in Europe using Bt Maize

Transgenic crops producing insecticidal proteins from _Bacillus thuringiensis_ (Bt) have been widely adopted since 1996 in the United States of America to combat important pests of maize and cotton. There is growing evidence that several target pest populations have been dramatically reduced in areas where the Bt crops have been most intensively adopted over multiple years. The evidence is most dramatic for nonmigratory monophagous and oligophagous species that show high mortality on Bt crops, such as European corn borer (_Ostrinia nubilalis_), and tobacco budworm (_Heliothis virescens_). Bt cotton is currently being used in the southwestern USA as part of an area-wide eradication program for pink bollworm (_Pectinophora gossypiella_). Single, stacked, and pyramided Bt maize lines producing coleopteran-active insecticidal proteins have been shown in some cases to cause >99% mortality of western corn rootworm (_Diabrotica virgifera virgifera_) larvae every year. Simulation models suggest that long-term area-wide cultivation of these Bt corn lines can lead to dramatic population reduction, and even local extinction, of corn rootworms. An eradication program for this economically important pest, based around Bt maize and incorporating a combination of other tools, would benefit European agriculture and the environment. Post-commercial monitoring programs should be designed to investigate long-term benefits to agricultural production systems that can be reasonably expected from the widespread cultivation of Bt crops in Europe

A comparison of incompressible limits for resistive plasmas

The constraint of incompressibility is often used to simplify the magnetohydrodynamic (MHD) description of linearized plasma dynamics because it does not affect the ideal MHD marginal stability point. In this paper two methods for introducing incompressibility are compared in a cylindrical plasma model: In the first method, the limit $\gamma \to \infty$ is taken, where $\gamma$ is the ratio of specific heats; in the second, an anisotropic mass tensor $\mathbf{\rho}$ is used, with the component parallel to the magnetic field taken to vanish, $\rho_{\parallel} \to 0$. Use of resistive MHD reveals the nature of these two limits because the Alfv\'en and slow magnetosonic continua of ideal MHD are converted to point spectra and moved into the complex plane. Both limits profoundly change the slow-magnetosonic spectrum, but only the second limit faithfully reproduces the resistive Alfv\'en spectrum and its wavemodes. In ideal MHD, the slow magnetosonic continuum degenerates to the Alfv\'en continuum in the first method, while it is moved to infinity by the second. The degeneracy in the first is broken by finite resistivity. For numerical and semi-analytical study of these models, we choose plasma equilibria which cast light on puzzling aspects of results found in earlier literature.Comment: 14 pages, 10 figure

New Radiocarbon-Dated Vertebrate Fossils from Herschel Island: Implications for the Palaeoenvironments and Glacial Chronology of the Beaufort Sea Coastlands

Palaeontological research on Herschel Island, Yukon, has yielded a diverse collection of Quaternary marine and terrestrial vertebrate fossils. The terrestrial faunal remains, which have largely been collected as allochthonous beach debris at Pauline Cove, are dominated by Yukon horse (Equus sp.), with fewer specimens of steppe bison (Bison priscus), proboscideans (Mammuthus primigenius and a single Mammut americanum specimen), and other large and medium-sized mammals. This pattern of a horse-dominated Late Pleistocene fauna is consistent with those from the North Slope of Alaska and further demonstrates that conditions in northernmost Beringia were more arid than those in interior areas such as Fairbanks or the Klondike. This paper presents new AMS radiocarbon dates on terrestrial vertebrate fossils and peat from the island that span the range from greater than 53 000 to modern 14C yr BP. When considered with other data from the region, our new radiocarbon-dated fauna cannot adequately resolve whether the Herschel Island ice-thrust ridge was formed during the Early Wisconsinan or the Late Wisconsinan advance of the Laurentide Ice Sheet over the Yukon Coastal Plain.Des fouilles paléontologiques réalisées sur l’île Herschel, au Yukon, ont permis de prélever une collection variée de fossiles marins et de fossiles vertébrés terrestres du quaternaire. Les restes de faune terrestre, qui ont surtout été ramassés sous la forme de débris de plage allochtones à Pauline Cove, prennent la forme de restes de chevaux du Yukon en prédominance (Equus sp.), parsemés de quelques spécimens de bisons priscus (Bison priscus), de proboscidiens (Mammuthus primigenius et d’un seul spécimen de Mammut americanum), ainsi que d’autres mammifères de taille moyenne et de grande taille. La prédominance de faune du type cheval du Pléistocène tardif correspond à celle enregistrée sur le versant nord de l’Alaska et montre encore une fois que les conditions qui régnaient dans la partie la plus au nord de la Béringie étaient plus arides que les conditions qui prévalaient dans les régions de l’intérieur, comme à Fairbanks ou au Klondike. Dans ce document, nous présentons de nouvelles dates établies par le radiocarbone SMAquant aux fossiles de vertébrés terrestres et à la tourbe de l’île, dates allant de plus de 53 000 14C années BP à l’ère moderne. Lorsque ces données sont considérées à la lumière d’autres données de la région, la nouvelle faune datée par le radiocarbone ne nous permet pas de déterminer adéquatement si la dorsale découlant de la poussée des glaces de l’île Herschel a été formée pendant la progression du Wisconsinien précoce ou du Wisconsinien tardif de la nappe glaciaire laurentienne sur la plaine côtière du Yukon

Adjusted estimates for time-to-event endpoints.

In the analysis of retrospective data or when interpreting results from a single-arm phase II clinical trial relative to historical data, it is often of interest to show plots summarizing time-to-event outcomes comparing treatment groups. If the groups being compared are imbalanced with respect to factors known to influence outcome, these plots can be misleading and seemingly incompatible with results obtained from a regression model that accounts for these imbalances. We consider ways in which covariate information can be used to obtain adjusted curves for time-to-event outcomes. We first review a common model-based method and then suggest another model-based approach that is not as reliant on model assumptions. Finally, an approach that is partially model free is suggested. Each method is applied to an example from hematopoietic cell transplantation

Searching of gapped repeats and subrepetitions in a word

A gapped repeat is a factor of the form $uvu$ where $u$ and $v$ are nonempty words. The period of the gapped repeat is defined as $|u|+|v|$. The gapped repeat is maximal if it cannot be extended to the left or to the right by at least one letter with preserving its period. The gapped repeat is called $\alpha$-gapped if its period is not greater than $\alpha |v|$. A $\delta$-subrepetition is a factor which exponent is less than 2 but is not less than $1+\delta$ (the exponent of the factor is the quotient of the length and the minimal period of the factor). The $\delta$-subrepetition is maximal if it cannot be extended to the left or to the right by at least one letter with preserving its minimal period. We reveal a close relation between maximal gapped repeats and maximal subrepetitions. Moreover, we show that in a word of length $n$ the number of maximal $\alpha$-gapped repeats is bounded by $O(\alpha^2n)$ and the number of maximal $\delta$-subrepetitions is bounded by $O(n/\delta^2)$. Using the obtained upper bounds, we propose algorithms for finding all maximal $\alpha$-gapped repeats and all maximal $\delta$-subrepetitions in a word of length $n$. The algorithm for finding all maximal $\alpha$-gapped repeats has $O(\alpha^2n)$ time complexity for the case of constant alphabet size and $O(n\log n + \alpha^2n)$ time complexity for the general case. For finding all maximal $\delta$-subrepetitions we propose two algorithms. The first algorithm has $O(\frac{n\log\log n}{\delta^2})$ time complexity for the case of constant alphabet size and $O(n\log n +\frac{n\log\log n}{\delta^2})$ time complexity for the general case. The second algorithm has $O(n\log n+\frac{n}{\delta^2}\log \frac{1}{\delta})$ expected time complexity

Estimativa do nível crítico de cobre para a soja, em solos do cerrado brasileiro.

A prática da monocultura de soja no Brasil, com o passar do tempo, pode diminuir o teor de matéria orgânica dos solos, sendo esse problema mais sério em solos arenosos. Isso tem aumentado a deficiência de certos micronutrientes, em especial o cobre (Cu). Além disso, a aplicação de adubos, muitas vezes em demasia e sem critério técnico, pode provocar problemas nutricionais de toxicidade ou deficiência desse micronutriente. Com a expansão da soja nas regiões de solos de Cerrado, passou-se para o cultivo em solos de textura média a arenosa, com teores de argila inferiores a 200 g.kg-1, CTC baixa e, originalmente, com baixo teor de Cu. Foram instalados experimentos, com a cultura da soja, em três solos do Cerrado: Latossolo Vermelho Amarelo (LVA) com 260 g.kg-1 de argila, no município de Tasso Fragoso, Latossolo Vermelho (LV) com 450 g.kg-1 de argila, no município de São Raimundo das Mangabeiras, ambos no sul do Estado do Maranhão e em Latossolo Vermelho (LV) com 550 g.kg-1 de argila, no município de Pedra Preta, sudeste do Estado do Mato Grosso, com seis doses de Cu (0; 1,25; 2,5; 5,0; 10 e 20 kg/ha), da fonte sulfato de cobre (30% de Cu) e seis níveis de saturação de bases (V%=30, 40, 50, 60, 70 e 80), com quatro repetições. Os valores estimados, acima dos quais não é esperada resposta à aplicação de cobre, são de 0,74 mg.dm-3 e 0,34 mg.dm-3 de Cu2+, pelos métodos Mehlich e DTPA, respectivamente. Portanto, as faixas de Cu no solo em mg.dm-3, para interpretação dos níveis do nutriente no solo são: para o Método Mehlich-1; Baixo 0,74. Para o Método DTPA; Baixo 0,34

The management of subjective quality of life by short-stay hospital patients: An exploratory study

BACKGROUND: This study tested the homeostatic model of subjective quality of life in a group of 47 short stay patients as they progressed through the stages of hospitalization for surgery. METHOD: Participants completed a questionnaire measuring subjective quality of life, positive and negative affect, self-esteem, optimism and cognitive flexibility, the day prior to admission (T1), two days post-operation (T2) and one week after discharge (T3). Neuroticism and Extroversion were measured at Time 1. RESULTS: All variables remained stable across the three times, apart from positive affect, which dropped significantly post-operation but returned to its previous level post discharge. CONCLUSION: Although the homeostatic model of subjective quality of life was supported at Time 1, the analyses raise doubts about the stability of personality. This finding is consistent with recent discussions of personality

Global response of clear-air turbulence to climate change

Clear-air turbulence (CAT) is one of the largest causes of weather-related aviation incidents. Here we use climate model simulations to study the impact that climate change could have on global CAT by the period 2050–2080. We extend previous work by analyzing eight geographic regions, two flight levels, five turbulence strength categories, and four seasons. We find large relative increases in CAT, especially in the midlatitudes in both hemispheres, with some regions experiencing several hundred per cent more turbulence. The busiest international airspace experiences the largest increases, with the volume of severe CAT approximately doubling over North America, the North Pacific, and Europe. Over the North Atlantic, severe CAT in future becomes as common as moderate CAT historically. These results highlight the increasing need to improve operational CAT forecasts and to use them effectively in flight planning, to limit discomfort and injuries among passengers and crew

Linking tree growth rate, damage repair, and susceptibility to a genus-specific pest infestation

Pest preference and subsequent susceptibility of a host individual is likely related to previous growth patterns in that host. Emerald ash borer (Agrilus planipennis Fairmaire) is a pestiferous beetle introduced to North America from Asia. While all species of ash are susceptible to attack, some individual trees appear to survive infestation. We selected ash trees in southeastern Michigan, collected cores and categorized trees as high tolerance to emerald ash borer attack (high overall health, low crown dieback), low tolerance (low overall health, high crown dieback) and intermediate tolerance (in-between the other categories). We artificially wounded trees and measured wound closure after 3 years. Ring width indices were not correlated between high and low tolerance trees. Regression slopes comparing growth and years were significantly different between the three tolerance categories, with high tolerance trees having the steepest slope. Wound closure was greatest in high tolerance trees. High tolerance trees demonstrating more rapid (steeper regression slope), consistent (lower variance), and effective (greater wound closure) growth. Those vigorously growing trees likely had more capacity to repair damage caused by emerald ash borer, leading to healthier trees in our categorization. Linking previous host growth patterns to health may have implications related to identifying individual trees potentially tolerant to attack