367 research outputs found
Fine-scale movements and behaviors of coyotes (Canis latrans) during their reproductive period
In canids, resident breeders hold territories but require different resources than transient individuals (i.e., dispersers), which may result in differential use of space, land cover, and food by residents and transients. In the southeastern United States, coyote (Canis latrans) reproduction occurs during spring and is energetically demanding for residents, but transients do not reproduce and therefore can exhibit feeding behaviors with lower energetic rewards. Hence, how coyotes behave in their environment likely differs between resident and transient coyotes. We captured and monitored 36 coyotes in Georgia during 2018ā2019 and used data from 11 resident breeders, 12 predispersing residents (i.e., offspring of resident breeders), and 11 transients to determine space use, movements, and relationships between these behaviors and landcover characteristics. Average home range size for resident breeders and predispersing offspring was 20.7 Ā± 2.5 kmĀ² and 50.7 Ā± 10.0 kmĀ², respectively. Average size of transient ranges was 241.4 Ā± 114.5 kmĀ². Daily distance moved was 6.3 Ā± 3.0 km for resident males, 5.5 Ā± 2.7 km for resident females, and 6.9 Ā± 4.2 km for transients. We estimated first-passage time values to assess the scale at which coyotes respond to their environment, and used behavioral change-point analysis to determine that coyotes exhibited three behavioral states. We found notable differences between resident and transient coyotes in regard to how landcover characteristics influenced their behavioral states. Resident coyotes tended to select for areas with denser vegetation while resting and foraging, but for areas with less dense vegetation and canopy cover when walking. Transient coyotes selected areas closer to roads and with lower canopy cover while resting, but for areas farther from roads when foraging and walking. Our findings suggest that behaviors of both resident and transient coyotes are influenced by varying landcover characteristics, which could have implications for prey
Acquiring Articles through Unmediated, User-Initiated Pay-Per-View Transactions: An Assessment of Current Practices
Depressed economic times often lead libraries to consider new practices, including alternatives to the traditional subscription model. This column discusses a pay-per-view (PPV) model for acquiring journal articles whereby a library creates an account with a content provider through which authenticated users can purchase articles at the libraryĆ¢ā¬ā¢s expense. To gain insight into the current use of this model, the paper draws on both a literature review and the results of a survey assessing the practices of academic libraries with experience acquiring articles through unmediated, user-initiated pay-per-view transactions. The future of the PPV model as well as issues and challenges that it raises are also considered
Fractal geometry of spin-glass models
Stability and diversity are two key properties that living entities share
with spin glasses, where they are manifested through the breaking of the phase
space into many valleys or local minima connected by saddle points. The
topology of the phase space can be conveniently condensed into a tree
structure, akin to the biological phylogenetic trees, whose tips are the local
minima and internal nodes are the lowest-energy saddles connecting those
minima. For the infinite-range Ising spin glass with p-spin interactions, we
show that the average size-frequency distribution of saddles obeys a power law
, where w=w(s) is the number of minima that can be
connected through saddle s, and D is the fractal dimension of the phase space
Dietary Docosahexaenoic Acid Reduces Oscillatory Wall Shear Stress, Atherosclerosis, and Hypertension, Most Likely Mediated via an ILā1āMediated Mechanism
Background: Hypertension is a complex condition and a common cardiovascular risk factor. Dietary docosahexaenoic acid (DHA) modulates atherosclerosis and hypertension, possibly via an inflammatory mechanism. ILā1 (interleukin 1) has an established role in atherosclerosis and inflammation, although whether ILā1 inhibition modulates blood pressure is unclear.
Methods and Results: Male apoEā/ā (apolipoprotein Eānull) mice were fed either a high fat diet or a high fat diet plus DHA (300 mg/kg per day) for 12 weeks. Blood pressure and cardiac function were assessed, and effects of DHA on wall shear stress and atherosclerosis were determined. DHA supplementation improved left ventricular function, reduced wall shear stress and oscillatory shear at ostia in the descending aorta, and significantly lowered blood pressure compared with controls (119.5Ā±7 versus 159.7Ā±3 mm Hg, P<0.001, n=4 per group). Analysis of atheroma following DHA feeding in mice demonstrated a 4āfold reduction in lesion burden in distal aortas and in brachiocephalic arteries (P<0.001, n=12 per group). In addition, DHA treatment selectively decreased plaque endothelial ILā1Ī² (P<0.01).
Conclusions: Our findings revealed that raised blood pressure can be reduced by inhibiting ILā1 indirectly by administration of DHA in the diet through a mechanism that involves a reduction in wall shear stress and local expression of the proinflammatory cytokine ILā1Ī²
Fresh Surgical Specimens Yield Breast Stem/Progenitor Cells and Reveal Their Oncogenic Abnormalities
External sources of clean technology: evidence from the clean development mechanism
New technology is fundamental to sustainable development. However, inventors from industrialized countries often refuse technology transfer because they worry about reverse-engineering. When can clean technology transfer succeed? We develop a formal model of the political economy of NorthāSouth technology transfer. According to the model, technology transfer is possible if (1) the technology in focus has limited global commercial potential or (2) the host developing country does not have the capacity to absorb new technologies for commercial use. If both conditions fail, inventors from industrialized countries worry about the adverse competitiveness effects of reverse-engineering, so technology transfer fails. Data analysis of technology transfer in 4,894 projects implemented under the Kyoto Protocolās Clean Development Mechanism during the 2004ā2010 period provides evidence in support of the model
- ā¦