Spreading and shortest paths in systems with sparse long-range connections

Spreading according to simple rules (e.g. of fire or diseases), and shortest-path distances are studied on d-dimensional systems with a small density p per site of long-range connections (``Small-World'' lattices). The volume V(t) covered by the spreading quantity on an infinite system is exactly calculated in all dimensions. We find that V(t) grows initially as t^d/d for t>t^*$, generalizing a previous result in one dimension. Using the properties of V(t), the average shortest-path distance \ell(r) can be calculated as a function of Euclidean distance r. It is found that \ell(r) = r for r<r_c=(2p \Gamma_d (d-1)!)^{-1/d} log(2p \Gamma_d L^d), and \ell(r) = r_c for r>r_c. The characteristic length r_c, which governs the behavior of shortest-path lengths, diverges with system size for all p>0. Therefore the mean separation s \sim p^{-1/d} between shortcut-ends is not a relevant internal length-scale for shortest-path lengths. We notice however that the globally averaged shortest-path length, divided by L, is a function of L/s only.Comment: 4 pages, 1 eps fig. Uses psfi

Non-nequilibrium model on Apollonian networks

We investigate the Majority-Vote Model with two states ($-1,+1$) and a noise $q$ on Apollonian networks. The main result found here is the presence of the phase transition as a function of the noise parameter $q$. We also studies de effect of redirecting a fraction $p$ of the links of the network. By means of Monte Carlo simulations, we obtained the exponent ratio $\gamma/\nu$, $\beta/\nu$, and $1/\nu$ for several values of rewiring probability $p$. The critical noise was determined $q_{c}$ and $U^{*}$ also was calculated. The effective dimensionality of the system was observed to be independent on $p$, and the value $D_{eff} \approx1.0$ is observed for these networks. Previous results on the Ising model in Apollonian Networks have reported no presence of a phase transition. Therefore, the results present here demonstrate that the Majority-Vote Model belongs to a different universality class as the equilibrium Ising Model on Apollonian Network.Comment: 5 pages, 5 figure

An Investigation of Whimbrel Stopover and Migration Ecology on the Eastern Shore of Virginia

1) To determine spatial use and activity budgets of whimbrels during spring and fall migration including foraging rates, the influence of tide cycle on activities, the location of roosting sites, and opportunistic resighting of any previously tagged whimbrels in Virginia. 2) Conduct ongoing “Whimbrel Watch” program at Box Tree Creek, Virginia

An Assessment of the Bald Eagle and Great Blue Heron Breeding Populations along High Rock, Tuckertown, Narrows, and Falls Reservoirs in Central North Carolina: 2012 Breeding Season

Intro and Objectives: Historically, the Bald Eagle was a common breeding species along major river systems, lakes and coastal areas throughout much of North America. The widespread use of persistent pesticides for crop management in the region resulted in dramatic declines over a 30-40 year period. By the late 1960s, most breeding populations had been decimated by eggshell thinning and associated low productivity. Concern for these populations prompted the elevation of the Bald Eagle to endangered status and led to a national effort to restore historic populations. Since the nationwide ban on many persistent pesticides in 1972, many populations have experienced gradual recoveries in productivity and total numbers. The state of North Carolina has seen an increase from no breeding pairs in the late 1960s to approximately 136 pairs as of 2008. Work conducted by The Center for Conservation Biology in 1995 and 1996 at Alcoa Power Generating Inc.’s (APGI) Yadkin Project (FERC #2197) identified areas of consistent use by eagles in inland areas of North Carolina and suggested that nesting activity should be anticipated in the Yadkin-Pee Dee River basin. A survey of this system in 2001 provided confirmation of these suggestions. Since that survey annual efforts to monitor this population have continued. Results of the 2012 survey follow (a summary of all eagle nesting activity since 2001 is provided at the end of this report). Objectives The objectives of the eagle survey on Yadkin Project reservoirs were 1) to document the status, distribution and productivity of nesting pairs in association with the Yadkin reservoirs and associated river corridors and 2) to increase our understanding of Bald Eagle natural history in interior regions of North Carolina. A third objective was to determine the status and distribution of breeding Great Blue Herons along the system of reservoirs

Inverted Echo Sounder (IES) Instrument Report

The Inverted Echo Sounder (IES) is an ocean-bottom moored instrument which accurately measures the time required for an acoustic pulse to travel from the sea floor to the ocean surface and back. The round-trip acoustic travel time varies in response to changes in the mean temperature profile of the water column above the instrument, as well as changes in water depth. The instrument is used as a sensitive indicator of changes in the main thermocline depth caused by synoptic-scale eddies or the shifting path of an ocean current. The IES is small (17 -diameter glass sphere) and self-contained, with its own acoustic release, relocation and recovery system. Its battery capacity and digital tape recorder (data capacity 107 bits) allow it to be deployed for up to 18 months. It can operate in water depths of up to 6700 m and requires only an anchor as mooring equipment. Microprocessor-based electronics allow programmable data formatting and sampling cycles. Additional data channels for pressure, temperature, and ambient noise are optional. The system has undergone extensive development and field testing, resulting in a reliable, cost-effective means to study temporal variability in large-scale features of the temperature field of the oceans

Surveys and Habitat Use of the Whimbrel (Numenius phaeopus) During Fall Migration Along the Acadian Peninsula of New Brunswick, Canada, 2014

The whimbrel (Numenius phaeopus) is a large, highly migratory shorebird that breeds in arctic and sub-arctic latitudes and winters in the tropics. The North American race (N.p. hudsonicus) includes three disjunct breeding populations, all of which winter primarily in Central and South America. The two rufiventris populations breed in Alaska and the Northwest Territories of Canada (Engelmoer and Roselaar 1998). These western whimbrels primarily use different migration routes and wintering grounds and are most likely genetically segregated populations (CCB/CWS unpublished tracking data). The hudsonicus population breeds in the Hudson Bay Lowlands along the James and Hudson Bays (Jehl and Smith 1970, Skeel and Mallory 1996). The populations of whimbrels utilizing the Atlantic Coast and northeast South America have declined by up to 50% in recent decades (Watts and Truitt 2011, and RIG Morrison et al., unpublished data, from Andres et al. 2012) and both the hudsonicus and Northwest Territories rufiventris populations are of conservation concern (Morrison 2006, Bart et al. 2007, Watts and Truitt 2011). In an effort to better understand the population size and habitat use of whimbrels utilizing the Acadian peninsula during fall migration, we designed aerial and ground based surveys to accomplish this goal. We detected 339 whimbrels during the first aerial survey and 615 during the second survey. Whimbrels were distributed along the peninsula from Brantville to Miscou Island, though concentrations of whimbrels were higher near Miscou Island. Of the 954 whimbrels detected on aerial surveys, 908 (95%) were observed in harvest stage fields, 5 ( \u3c 1 %) in development stage fields, 7 ( \u3c 1%) flushed from unknown stage fields, and 34 (3.5%) from coastal beaches or barrier islands. We surveyed 103 ground transects twice each during the field season. We surveyed a total length of 58.5 km of transects within the five geographic areas (Brantville, Lord and Foy, Val-Doucet, Tracadie-Sheila, and Pigeon Hill/Lameque Island). We surveyed approximately 1,448 hectares of blueberry fields, with 773ha in active blueberry production, 653ha in growth stage, and 32ha in development. A total of 690 whimbrels were detected in the two survey rounds, with majority of detections in harvest stage fields (N = 637, 92%), and 53 detections (8%) in either growth or development stage. A total of 565 (82%) whimbrels detected during survey round 1, and 125 (18%) during survey round 2. The Acadian Peninsula of New Brunswick, Canada appears to support a significant portion of the total whimbrel population that uses Atlantic Canada in fall migration. Over 99% of all whimbrels detected during the aerial, ground, and evening roost surveys originated from blueberry fields, suggesting that tidal influences on behavior are negligible. Warden pressure on the whimbrels in the blueberry fields is quite high and needs to be addressed

Frequency and Distribution of Birds within Forested Wetlands – Breeding and Wintering Seasons

The life histories of approximately 350 bird species bring them to the Virginia portion of the Mid-Atlantic Coastal Plain, with nearly 180 species breeding within this region. The Mid-Atlantic Coastal Plain is the northern limit for many “southern” species, and the southern range limit for many “northern” species (Watts 1999). Many species of high conservation concern occupy Coastal Plain forested wetlands and adjacent marsh habitats (Watts 1999, Virginia Dept. of Game and Inland Fisheries 2005, North American Bird Conservation Initiative 2016). Recent declines in songbird populations have led to an increase in management and conservation efforts (Robinson et al. 1987, Suarez et al. 1997, Hunter et al. 2001, Lanham et al 2002, Sauer et al. 2013). The Center for Conservation Biology surveyed a total of 10 study sites three times during the summer of 2016 and the winter season of 2016-2017. These counts, consisting of area search and unlimited radius point count techniques, were used to measure frequency, occurrence, and species richness within select habitat patches in breeding and wintering habitats. . Habitats sampled during the two seasons include forested wetlands (from the headwaters of the wetland to the transition zone, characterized in general by mature hardwood forest), transition zone wetlands (from forested wetland edge to the edge of open marsh habitat, characterized by dense shrubby fringing habitat and an understory of freshwater marsh plants), and upland edge habitats along both headwater and transition wetlands (characterized by drier habitat dominated by pine and oak species). Aerial insectivores were recorded as utilizing the habitat that they were foraging over, while flyover species were simply recorded for presence/absence and not associated with habitat type. A total of 1,036 detections of 72 bird species were made during the breeding and wintering surveys, comprised of 29 neotropical migrant species, 24 temperate migrant species, and 18 non-migratory (resident) species. During the breeding season, a total of 626 birds of 49 species were detected, comprised of 25 neotropical species, 15 resident species, and 9 temperate migrant species. During the winter season, a total of 410 birds of 45 species were detected, comprised of 23 resident species, 17 temperate migrants, and 4 neotropical migrants. Three rounds of playback surveys were used to target the presence or absence of clapper rails during the 2016 breeding season. No clapper rails were detected within the study sites. The species observed during both seasons are typical of those found within the forested wetland habitats of coastal Virginia in the Mid-Atlantic region in both breeding and wintering seasons

Instability of scale-free networks under node-breaking avalanches

The instability introduced in a large scale-free network by the triggering of node-breaking avalanches is analyzed using the fiber-bundle model as conceptual framework. We found, by measuring the size of the giant component, the avalanche size distribution and other quantities, the existence of an abrupt transition. This test of strength for complex networks like Internet is more stringent than others recently considered like the random removal of nodes, analyzed within the framework of percolation theory. Finally, we discuss the possible implications of our results and their relevance in forecasting cascading failures in scale-free networks.Comment: 4 pages, 4 figures, final version to be published in Europhys. Let

STEPS - an approach for human mobility modeling

In this paper we introduce Spatio-TEmporal Parametric Stepping (STEPS) - a simple parametric mobility model which can cover a large spectrum of human mobility patterns. STEPS makes abstraction of spatio-temporal preferences in human mobility by using a power law to rule the nodes movement. Nodes in STEPS have preferential attachment to favorite locations where they spend most of their time. Via simulations, we show that STEPS is able, not only to express the peer to peer properties such as inter-ontact/contact time and to reflect accurately realistic routing performance, but also to express the structural properties of the underlying interaction graph such as small-world phenomenon. Moreover, STEPS is easy to implement, exible to configure and also theoretically tractable

Chaos in Small-World Networks

A nonlinear small-world network model has been presented to investigate the effect of nonlinear interaction and time delay on the dynamic properties of small-world networks. Both numerical simulations and analytical analysis for networks with time delay and nonlinear interaction show chaotic features in the system response when nonlinear interaction is strong enough or the length scale is large enough. In addition, the small-world system may behave very differently on different scales. Time-delay parameter also has a very strong effect on properties such as the critical length and response time of small-world networks