Correlation of stress-wave-emission characteristics with fracture in aluminum alloys, 1 September - 1 December 1969

Cryogenic testing of aluminum alloy specimens for fracture toughness and stress wave dat

Stress-wave analysis technique study on thick-walled type A302B steel pressure vessels, July 1968 - July 1969

Stress wave analysis and crack opening displacement to monitor subcritical crack growth for grade B alloy steel pressure vessel

Monitoring of crack growth in Ti-Al-4v alloy by the stress wave analysis technique

Stress wave analysis techniques for monitoring crack growth in Ti-6Al-4V alloy pressure vessel wall

Winter Habitat Associations of Blackbirds and Starlings Wintering in the South-Central United States

Birds can cause extensive crop damage in the United States. In some regions, depredating species comprise a substantial portion of the total avian population, emphasizing their importance both economically and ecologically. We used the National Audubon Society Christmas Bird Count data from the south-central United States and mixed-effects models to identify habitat factors associated with population trend and abundance for 5 species: red-winged blackbird (Agelaius phoeniceus), common grackle (Quiscalus quiscula), rusty blackbird (Euphagus carolinus), Brewer’s blackbird (Euphagus cyanocephalus), and European starling (Sturnus vulgaris). Overall, we found positive associations between bird abundance and agricultural land-cover for all species. Relationships between abundance and other land-cover types were species-specific, often with contrasting relationships among species. Likewise, we found no consistent patterns among abundance and climate. Of the 5 species, only red-winged blackbirds had a significant population trend in our study area, increasing annually by 2.4%. There was marginal evidence to suggest population increases for rusty blackbirds, whereas all other species showed no trend in population size within our study area. Our study provides managers who are interested in limiting crop damage in the south-central United States with novel information on habitat associations in the region that could be used to improve management and control action

Notes

Notes by Francis W. Brown, Thomas E. Coughlan, John M. Crimmins, Thomas Gately, Thos. L. McKevitt, and Francis M. Marley

Characteristics of Non-Fatal Attacks by Black Bears: Conterminous United States, 2000–2017

Attacks on humans by bears (Ursus spp.) have increased in recent decades, as both human and bear populations have increased. To help mitigate the risk of future attacks, it is important to understand the circumstances in past attacks. Information and analyses exist regarding fatal attacks by both American black bears (Ursus americanus) and brown bears (U. arctos) as well as non-fatal attacks by brown bears. No similarly thorough analyses on non-fatal attacks by black bears are available. Our study addressed this information gap by analyzing all (n = 210) agency-confirmed, non-fatal attacks by black bears in the 48 conterminous United States during 2000 to 2017. Most attacks were defensive (52%), while 15% were predatory and 33% were food-motivated. Of defensive attacks, 85% were by female bears, and 91% of those females had young. Of predatory attacks, 95% were by male bears, and of food-motivated attacks, 80% were by male bears. Forty percent of defensive attacks by female bears involved dogs (Canis lupus familiaris). Sixty-four percent had an attractant present during the attack and 74% indicated there were reports of property damage by bears or of bears getting a food-reward in the area prior to the attack. A classification and regression tree model show the highest proportion of severe attacks were among a female victim who was with a dog and who fought back during an attack. When compared with previous studies of fatal attacks by black bears, which are typically predatory attacks by male bears, our results illustrate clear differences between fatal and non-fatal attacks. Our study also lends evidence to the hypothesis that dogs can trigger defensive attacks by black bears. These results have implications for risk assessment, attack mitigation, and how we advise the public to respond to an attacking bear

A new approach to generating research-quality data through citizen science: The USA National Phenology Monitoring System

Phenology is one of the most sensitive biological responses to climate change, and recent changes in phenology have the potential to shake up ecosystems. In some cases, it appears they already are. Thus, for ecological reasons it is critical that we improve our understanding of species’ phenologies and how these phenologies are responding to recent, rapid climate change. Phenological events like flowering and bird migrations are easy to observe, culturally important, and, at a fundamental level, naturally inspire human curiosity— thus providing an excellent opportunity to engage citizen scientists. The USA National Phenology Network has recently initiated a national effort to encourage people at different levels of expertise—from backyard naturalists to professional scientists—to observe phenological events and contribute to a national database that will be used to greatly improve our understanding of spatio-temporal variation in phenology and associated phenological responses to climate change.

Traditional phenological observation protocols identify specific dates at which individual phenological events are observed. The scientific usefulness of long-term phenological observations could be improved with a more carefully structured protocol. At the USA-NPN we have developed a new approach that directs observers to record each day that they observe an individual plant, and to assess and report the state of specific life stages (or phenophases) as occurring or not occurring on that plant for each observation date. Evaluation is phrased in terms of simple, easy-to-understand, questions (e.g. “Do you see open flowers?”), which makes it very appropriate for a citizen science audience. From this method, a rich dataset of phenological metrics can be extracted, including the duration of a phenophase (e.g. open flowers), the beginning and end points of a phenophase (e.g. traditional phenological events such as first flower and last flower), multiple distinct occurrences of phenophases within a single growing season (e.g multiple flowering events, common in drought-prone regions), as well as quantification of sampling frequency and observational uncertainties. These features greatly enhance the utility of the resulting data for statistical analyses addressing questions such as how phenological events vary in time and space, and in response to global change. This new protocol is an important step forward, and its widespread adoption will increase the scientific value of data collected by citizen scientists.
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A Highly Convergent Approach toward (−)-Brevenal

Progress toward a highly convergent, asymmetric synthesis of brevenal is reported. Construction of the AB-ring and E-ring cyclic ether fragments was achieved through asymmetric alkylation/ring-closing metathesis strategies. A Horner-Wadsworth-Emmons olefination was used in a key bond-forming step to couple the advanced cyclic fragments and enable rapid access to the AB-E ring system