Foray search: An effective systematic dispersal strategy in fragmented landscapes

In the absence of evidence to the contrary, population models generally assume that the dispersal trajectories of animals are random, but systematic dispersal could be more efficient at detecting new habitat and may therefore constitute a more realistic assumption. Here, we investigate, by means of simulations, the properties of a potentially widespread systematic dispersal strategy termed "foray search." Foray search was more efficient in detecting suitable habitat than was random dispersal in most landscapes and was less subject to energetic constraints. However, it also resulted in considerably shorter net dispersed distances and higher mortality per net dispersed distance than did random dispersal, and it would therefore be likely to lead to lower dispersal rates toward the margins of population networks. Consequently, the use of foray search by dispersers could crucially affect the extinction-colonization balance of metapopulations and the evolution of dispersal rates. We conclude that population models need to take the dispersal trajectories of individuals into account in order to make reliable predictions

SEARCH: Spatially Explicit Animal Response to Composition of Habitat.

Complex decisions dramatically affect animal dispersal and space use. Dispersing individuals respond to a combination of fine-scale environmental stimuli and internal attributes. Individual-based modeling offers a valuable approach for the investigation of such interactions because it combines the heterogeneity of animal behaviors with spatial detail. Most individual-based models (IBMs), however, vastly oversimplify animal behavior and such behavioral minimalism diminishes the value of these models. We present program SEARCH (Spatially Explicit Animal Response to Composition of Habitat), a spatially explicit, individual-based, population model of animal dispersal through realistic landscapes. SEARCH uses values in Geographic Information System (GIS) maps to apply rules that animals follow during dispersal, thus allowing virtual animals to respond to fine-scale features of the landscape and maintain a detailed memory of areas sensed during movement. SEARCH also incorporates temporally dynamic landscapes so that the environment to which virtual animals respond can change during the course of a simulation. Animals in SEARCH are behaviorally dynamic and able to respond to stimuli based upon their individual experiences. Therefore, SEARCH is able to model behavioral traits of dispersing animals at fine scales and with many dynamic aspects. Such added complexity allows investigation of unique ecological questions. To illustrate SEARCH\u27s capabilities, we simulated case studies using three mammals. We examined the impact of seasonally variable food resources on the weight distribution of dispersing raccoons (Procyon lotor), the effect of temporally dynamic mortality pressure in combination with various levels of behavioral responsiveness in eastern chipmunks (Tamias striatus), and the impact of behavioral plasticity and home range selection on disperser mortality and weight change in virtual American martens (Martes americana). These simulations highlight the relevance of SEARCH for a variety of applications and illustrate benefits it can provide for conservation planning

An integrated assessment of the potential impacts of climate change on Indiana forests

Forests provide myriad ecosystem services, many of which are vital to local and regional economies. Consequently, there is a need to better understand how predicted changes in climate will impact forests dynamics and the implications of such changes for society as a whole. Here we focus on the impacts of climate change on Indiana forests, which are representative of many secondary growth broadleaved forests in the greater Midwest region in terms of their land use history and current composition. We find that predicted changes in climate for the state – warmer and wetter winters/springs and hotter and potentially drier summers – will dramatically shape forest communities, resulting in new assemblages of trees and wildlife that differ from forest communities of the past or present. Overall, suitable habitat is expected to decline for 17-29 percent of tree species and increase for 43-52 percent of tree species in the state, depending on the region and climate scenario. Such changes have important consequences for wildlife that depend on certain tree species or have ranges with strong sensitivities to climate. Additionally, these changes will have potential economic impacts on Indiana industries that depend on forest resources and products (both timber and non-timber). Finally, we offer some practical suggestions on how management may minimize the extent of climate-induced ecological impacts, and highlight a case study from a tree planting initiative currently underway in the Patoka River National Wildlife Refuge and Management Area

Indiana\u27s Future Forests: A Report from the Indiana Climate Change Impacts Assessment

Over the next century, rising temperatures and changing precipitation patterns across the Midwest will likely have profound consequences for Indiana’s forests. Such changes include shifts in the distributions and abundances of trees, understory plants and wildlife, as well as changes to the environmental, economic and cultural benefits these forests provide. This report from the Indiana Climate Change Impacts Assessment (IN CCIA) examines the direct and indirect impacts that climate change is expected to have on Indiana’s forests. The report specifically addresses forest regeneration, forest composition, tree growth and harvest, wildlife habitat and forest products

Exceptionally Slow Rise in Differential Reflectivity Spectra of Excitons in GaN: Effect of Excitation-induced Dephasing

Femtosecond pump-probe (PP) differential reflectivity spectroscopy (DRS) and four-wave mixing (FWM) experiments were performed simultaneously to study the initial temporal dynamics of the exciton line-shapes in GaN epilayers. Beats between the A-B excitons were found \textit{only for positive time delay} in both PP and FWM experiments. The rise time at negative time delay for the differential reflection spectra was much slower than the FWM signal or PP differential transmission spectroscopy (DTS) at the exciton resonance. A numerical solution of a six band semiconductor Bloch equation model including nonlinearities at the Hartree-Fock level shows that this slow rise in the DRS results from excitation induced dephasing (EID), that is, the strong density dependence of the dephasing time which changes with the laser excitation energy.Comment: 8 figure

Improving the forecast for biodiversity under climate change

Acknowledgments: This paper originates from the “Ecological Interactions and Range Evolution Under Environmental Change” and “RangeShifter” working groups, supported by the Synthesis Centre of the German Centre for Integrative Biodiversity Research (DFG-FZT-118), DIVERSITAS, and its core projects bioDISCOVERY and bioGENESIS. Supported by the Canada Research Chair, Natural Sciences and Engineering Research Council of Canada, and Quebec Centre for Biodiversity Science (A.G.); the University of Florida Foundation (R.D.H.); KU Leuven Research Fund grant PF/2010/07, ERA-Net BiodivERsA TIPPINGPOND, and Belspo IAP SPEEDY (L.D.M.); European Union Biodiversity Observation Network grant EU-BON-FP7-308454 (J.-B.M. and G.P.); KU Leuven Research Fund (J.P.); and NSF grants DEB-1119877 and PLR-1417754 and the McDonnell Foundation (M.C.U.).Peer reviewedPostprin

Effect Of Nucleation Time With TMAl Preflow Assistance On Reducing Dislocation Density Of Aln Layer For

AlGaN-based UVC LEDs have now received numerous attentions due to their ability to eliminate coronaviruses which cause COVID-19 disease. It is therefore essential to improve the efficiency of the LEDs to make them compatible for large scale applications. One of the major challenges to improve the efficiency is to reduce the dislocation density in AlN layer; the base layer for the LEDs, to be below 109 cm-2. Thus far, many works have been proposed to reduce the dislocation in the AlN layer. However, by properly adjusting the AlN nucleation time in the growth of the AlN layer, the dislocation can be reduced. The effect might be more significant with TMAl preflow assistance, which is applied after the growth of the nucleation. In this work, we will present the effect of the nucleation time with the assistance of TMAl preflow on reducing the dislocation density in the overgrown AlN layer. With 60 seconds of nucleation, the density of the dislocation in the AlN layer can be as low as 9.0 x 108 cm-2. In addition. the role of the TMAl preflow assistance will be justified. The AlN layer was subsequently used to grow a 255 nm UVC LED. The diode characteristic and CL emission of the LED will be discussed towards the endof the presentation

Effect Of Nucleation Time With Tmal Preflow Assistance On Reducing Dislocation Density Of Aln Layer For AlGaN-Based UVC LED

AlGaN-based UVC LEDs have now received numerous attentions due to their ability to eliminate coronaviruses which cause COVID-19 disease. It is therefore essential to improve the efficiency of the LEDs to make them compatible for large scale applications. One of the major challenges to improve the efficiency is to reduce the dislocation density in AlN layer; the base layer for the LEDs, to be below 109 cm-2 . Thus far, many works have been proposed to reduce the dislocation in the AlN layer. However, by properly adjusting the AlN nucleation time in the growth of the AlN layer, the dislocation can be reduced. The effect might be more significant with TMAl preflow assistance, which is applied after the growth of the nucleation. In this work, we will present the effect of the nucleation time with the assistance of TMAl preflow on reducing the dislocation density in the overgrown AlN layer. With 60 seconds of nucleation, the density of the dislocation in the AlN layer can be as low as 9.0 x 108 cm-2 . In addition. the role of the TMAl preflow assistance will be justified. The AlN layer was subsequently used to grow a 255 nm UVC LED. The diode characteristic and CL emission of the LED will be discussed towards the end of the presentation

Macroscopic superposition states of ultracold bosons in a double-well potential

We present a thorough description of the physical regimes for ultracold bosons in double wells, with special attention paid to macroscopic superpositions (MSs). We use a generalization of the Lipkin-Meshkov-Glick Hamiltonian of up to eight single particle modes to study these MSs, solving the Hamiltonian with a combination of numerical exact diagonalization and high-order perturbation theory. The MS is between left and right potential wells; the extreme case with all atoms simultaneously located in both wells and in only two modes is the famous NOON state, but our approach encompasses much more general MSs. Use of more single particle modes brings dimensionality into the problem, allows us to set hard limits on the use of the original two-mode LMG model commonly treated in the literature, and also introduces a new mixed Josephson-Fock regime. Higher modes introduce angular degrees of freedom and MS states with different angular properties.Comment: 15 pages, 8 figures, 1 table. Mini-review prepared for the special issue of Frontiers of Physics "Recent Progresses on Quantum Dynamics of Ultracold Atoms and Future Quantum Technologies", edited by Profs. Lee, Ueda, and Drummon

Decreased expression of breast cancer resistance protein in the duodenum in patients with obstructive cholestasis

Background/Aims: The expression of transporters involved in bile acid homeostasis is differentially regulated during obstructive cholestasis. Since the drug efflux transporter breast cancer resistance protein (BCRP) is known to transport bile acids, we investigated whether duodenal BCRP expression could be altered during cholestasis. Methods: Using real-time RT-PCR analysis we determined mRNA expression levels in duodenal tissue of 19 cholestatic patients. Expression levels were compared to 14 healthy subjects. BCRP protein staining was determined in biopsies of 6 cholestatic and 6 healthy subjects by immunohistochemistry. Results: We found that in patients with obstructive cholestasis mean duodenal BCRP mRNA levels were significantly reduced to 53% and mean protein staining was reduced to 57%. Conclusions: BCRP, a transporter for bile acids and numerous drugs, appears to be down-regulated in the human duodenum during cholestasis. The clinical impact of these results has to be investigated in further studies. Copyright (c) 2006 S. Karger AG, Basel