Epsilon-Near-Zero Al-Doped ZnO for Ultrafast Switching at Telecom Wavelengths: Outpacing the Traditional Amplitude-Bandwidth Trade-Off

Transparent conducting oxides have recently gained great attention as CMOS-compatible materials for applications in nanophotonics due to their low optical loss, metal-like behavior, versatile/tailorable optical properties, and established fabrication procedures. In particular, aluminum doped zinc oxide (AZO) is very attractive because its dielectric permittivity can be engineered over a broad range in the near infrared and infrared. However, despite all these beneficial features, the slow (> 100 ps) electron-hole recombination time typical of these compounds still represents a fundamental limitation impeding ultrafast optical modulation. Here we report the first epsilon-near-zero AZO thin films which simultaneously exhibit ultra-fast carrier dynamics (excitation and recombination time below 1 ps) and an outstanding reflectance modulation up to 40% for very low pump fluence levels (< 4 mJ/cm2) at the telecom wavelength of 1.3 {\mu}m. The unique properties of the demonstrated AZO thin films are the result of a low temperature fabrication procedure promoting oxygen vacancies and an ultra-high carrier concentration. As a proof-of-concept, an all-optical AZO-based plasmonic modulator achieving 3 dB modulation in 7.5 {\mu}m and operating at THz frequencies is numerically demonstrated. Our results overcome the traditional "modulation depth vs. speed" trade-off by at least an order of magnitude, placing AZO among the most promising compounds for tunable/switchable nanophotonics.Comment: 14 pages, 9 figures, 1 tabl

Theory of sound attenuation in glasses: The role of thermal vibrations

Sound attenuation and internal friction coefficients are calculated for a realistic model of amorphous silicon. It is found that, contrary to previous views, thermal vibrations can induce sound attenuation at ultrasonic and hypersonic frequencies that is of the same order or even larger than in crystals. The reason is the internal-strain induced anomalously large Gr\"uneisen parameters of the low-frequency resonant modes.Comment: 8 pages, 3 figures; to appear in PR

Scavenger community response to the removal of a dominant scavenger

The alteration of scavenging communities can reduce basic ecosystem services and increase risks to human and wildlife health. Recent work demonstrated that scavenging communities in agricultural landscapes are extremely efficient: superabundant mesopredators sequestered system energy by dominating scavenging activity. To explore how the disturbance of these communities affects the stability of carrion removal as an ecosystem function, we experimentally manipulated a scavenging community within an agricultural landscape by reducing the abundance of the dominant scavenger, raccoons Procyon lotor. We then monitored the fates of 676 mouse Mus musculus carcasses placed in 13 control and 13 removal woodlots from June 2007 – May 2008. The diversity of vertebrate scavengers did not change between control and removal woodlots and scavenging by invertebrates was unaffected by our experiment. Although Virginia opossums Didelphis virginiana and other scavengers exhibited a functional response when raccoons were reduced in abundance, the increases did not change the proportional allocation of carcasses among scavengers. Finally, the reduced abundance of a major scavenger affected system efficiency. More carcasses remained un-scavenged at the end of trials in removal woodlots than in control woodlots. This experiment demonstrates the vulnerability of a critical ecosystem service, carrion removal, to perturbations of the scavenging community and serves to highlight the method by which scavenger communities may respond to perturbations

Scavenger removal of bird carcasses at simulated wind turbines: Does carcass type matter?

Wind energy development can negatively impact bird populations due to bird–turbine collisions. To accurately estimate bird mortality at wind farms, the number of dead birds found under turbines is commonly corrected for carcass removal by scavengers, which is quantified by measuring persistence of experimental carcasses through time. These studies often use domestic birds as surrogates because carcasses of wild birds (e.g., raptors) are difficult to obtain. We assessed scavenger removal of carcasses from five bird species at simulated turbines to determine whether domestic surrogates are scavenged at a different rate than raptors, species of interest for wind turbine mortality. The percentage of carcasses scavenged during 14-d rounds ranged from 34.6% for American kestrels (Falco sparverius) to 65.4% for chickens (Gallus gallus), and the percentage of carcasses completely removed ranged from 13.5% for red-tailed hawks (Buteo jamaicensis) to 67.3% for northern bobwhites (Colinus virginianus). Carcass type (i.e., species) was the only predictor included in the best-fit logistic regression model of complete carcass removal, and a survival analysis indicated carcass type influenced elapsed time to scavenging events. Our results suggest the use of surrogate species to quantify carcass removal at wind turbines could lead to inaccurate mortality estimates

Roads do not increase carrion use by a vertebrate scavenging community

Wildlife-vehicle collisions introduce a considerable amount of carrion into the environment, but scavenger use of this resource has not been extensively investigated. Scavengers may use roads for reliable foraging opportunities, but might also use roads for other purposes and encounter carrion opportunistically. We examined scavenging of carrion along linear features by placing 52 rabbit carcasses in each of three treatments in forested habitat during winter (Dec 2016-Mar 2017) in South Carolina, USA: roads, power line clearings (linear feature with fewer carcasses than roads due to lack of road kill), and forest interior. We used motion-activated cameras to compare arrival times and presence of vertebrate scavengers among treatments. There was no difference in proportion of carcasses scavenged or scavenger arrival time across treatments. No species arrived at roads quicker than other treatments. Turkey vultures (Cathartes aura) and coyotes (Canis latrans) scavenged equally across treatments, whereas gray foxes (Urocyon cinereoargenteus) scavenged along roads and power lines, but not in forests. We suggest that scavenger use of carrion near roads at this location during winter relates to factors other than carrion availability. Because some scavengers readily consumed carrion on roads, this resource has the potential to influence the ecology of these species

Quantum Origins of Molecular Recognition and Olfaction in Drosophila

The standard model for molecular recognition of an odorant is that receptor sites discriminate by molecular geometry as evidenced that two chiral molecules may smell very differently. However, recent studies of isotopically labeled olfactants indicate that there may be a molecular vibration-sensing component to olfactory reception, specifically in the spectral region around 2300 cm$^{-1}$. Here we present a donor-bridge-acceptor model for olfaction which attempts to explain this effect. Our model, based upon accurate quantum chemical calculations of the olfactant (bridge) in its neutral and ionized states, posits that internal modes of the olfactant are excited impulsively during hole transfer from a donor to acceptor site on the receptor, specifically those modes that are resonant with the tunneling gap. By projecting the impulsive force onto the internal modes, we can determine which modes are excited at a given value of the donor-acceptor tunneling gap. Only those modes resonant with the tunneling gap and are impulsively excited will give a significant contribution to the inelastic transfer rate. Using acetophenone as a test case, our model and experiments on D. melanogaster suggest that isotopomers of a given olfactant give rise to different odorant qualities. These results support the notion that inelastic scattering effects play a role in discriminating between isotopomers, but that this is not a general spectroscopic effectComment: 7 pages, 3 figure

Migratory Flyways May Affect Population Structure in Double‐Crested Cormorants

Double‐crested cormorants (Phalacrocorax auritus) recovered from a demographic bottleneck so well that they are now considered a nuisance species at breeding and wintering grounds across the United States and Canada. Management of this species could be improved by refining genetic population boundaries and assigning individuals to their natal population. Further, recent radio‐telemetry data suggest the existence of Interior and Atlantic migratory flyways, which could reduce gene flow and result in substantial genetic isolation. In this study, we used 1,784 individuals collected across the eastern United States, a large panel of microsatellite markers developed for this species, and individuals banded as chicks and recaptured as adults to explore the effects of migratory flyways on population structure, quantify the genetic effects of demographic bottlenecks, and determine whether individuals could be assigned to their natal population based on genotype. We found evidence for genetic population division only along migratory flyways, no evidence of genetic bottlenecks, and mixed effectiveness of assignment tests. Our population structure findings suggest that gene flow is high across large scales; for example, individuals from New York, Minnesota, and Alabama are all in panmixia. We also found that traditional subspecies ranges may not be valid because \u3e1 subspecies was present in single genetic populations. The lack of evidence for genetic bottlenecks also likely underscores the vagility of this species, suggesting that even during demographic bottlenecks, populations were not isolated from allelic exchange. Finally, the failure of assignment tests to consistently perform is likely due in part to imperfect a priori sampling of Atlantic and Interior chicks and the high vagility of adults. We conclude that the demographic bottleneck is not likely to have reduced genetic diversity, and that assignment tests remain unreliable for this species. We recommend double-crested cormorants be managed by flyway. Further development of genomic resources in this species could improve population subdivision resolution, improve assignment tests, and reveal further information on demographic histories

From 'River Cottage' to 'Chicken Run': Hugh Fearnley-Whttingstall and the class politics of ethical consumption

Lifestyle television provides a key site through which to explore the dilemmas of ethical consumption, as the genre shifts to consider the ethics of different consumption practices and taste cultures. UK television cook Hugh Fearnley-Whittingstall's TV programmes offer fertile ground not only for thinking about television personalities as lifestyle experts and moral entrepreneurs, but also for thinking about how the meanings and uses of their television image are inflected by genre. In this article we explore how the shift from the lifestyled downshifting narrative of the River Cottage series to the 'campaigning culinary documentary' Hugh's Chicken Run exposes issues of celebrity, class and ethics. While both series are concerned with ethical consumption, they work in different ways to reveal a distinction between 'ethical' and 'unethical' consumption practices and positions - positions that are inevitably classed

Mitigation Translocation of Red-Tailed Hawks to Reduce Raptor–Aircraft Collisions

Translocation of problematic individual animals is commonly used to reduce human–wildlife conflicts, especially to reduce the presence or abundance of raptors within airport environments, where they pose a risk to safe aircraft operations. Although this method has strong public support, there have been no scientific evaluations of its efficacy or to determine which factors might influence the return of translocated birds to the airport. We conducted a study to determine which biological and logistical factors might influence the return of red-tailed hawks (Buteo jamaicensis) translocated from Chicago’s O’Hare International Airport (ORD) during 2010–2013. We live-captured and translocated red-tailed hawks various distances from the ORD airfield and monitored for returning birds. We found the odds of hawk return increased by 2.36 (95% CI=0.99–5.70) times for older birds (\u3e1 yr of age) relative to younger birds (≤1yr of age). Odds of hawk return went up 4.10 (95% CI=0.75–22.2) times when translocations were conducted during the breeding season relative to the non-breeding season. The odds of hawk return increased 11.94 (95% CI=3.29–43.38) times for each subsequent translocation event involving the same hawk. The cost of 1 translocation event to the release sites that were 81, 121, 181, and 204 km from ORD was $213,$284, $362, and$426, respectively. Management programs that use release sites 80 km from the airport minimize translocation events to include only younger birds during the non-breeding season, and undertake only 1 translocation event for an individual hawk would increase program efficacy and greatly reduce program implementation costs. The decision matrix regarding the use of a raptor trapping and translocation program involves a variety of biological, logistical, economic, and sociopolitical variables. This study represents an important first step in providing a scientific foundation for informing such management decisions

Reducing Impacts of Double-crested Cormorants to Natural Resources in Central New York: A Review of a Collaborative Research, Management, and Monitoring Program

Double-crested Cormorants (Phalacrocorax auritus) have used central New York waters for breeding and stopover habitats during migration since 1984. In response to public concern over Oneida Lake, the United States Department of Agriculture Wildlife Services and the New York State Department of Environmental Conservation initiated an integrated research, management and monitoring program aimed at mitigating cormorant impacts to fisheries and other natural resources in 1998. The history of this program was reviewed and efforts to reduce negative impacts of the Double-crested Cormorant population in central New York described. Management was successful, as demonstrated by a substantial decrease in cormorant use of Oneida Lake during spring, summer and fall seasons, and the apparent recovery of certain sportfish populations. Research identified cormorant movement patterns within and among water bodies and documented cormorant responses to hazing and other management techniques. The cormorant management program in central New York was intended to keep cormorant use of Oneida Lake at a level that prevents unsustainable impacts to fisheries populations