2,807 research outputs found
Direct and indirect effects of temperature and prey abundance on bald eagle reproductive dynamics
Understanding the mechanisms by which populations are regulated is critical for predicting the effects of large-scale perturbations. While discrete mortality events provide clear evidence of direct impacts, indirect pathways are more difficult to assess but may play important roles in population and ecosystem dynamics. Here, we use multi-state occupancy models to analyze a long-term dataset on nesting bald eagles in south-central Alaska with the goal of identifying both direct and indirect mechanisms influencing reproductive output in this apex predator. We found that the probabilities of both nest occupancy and success were higher in the portion of the study area where water turbidity was low, supporting the hypothesis that access to aquatic prey is a critical factor limiting the reproductive output of eagles in this system. As expected, nest success was also positively related to salmon abundance; however, the negative effect of spring warmth suggested that access to salmon resources is indirectly diminished in warm springs as a consequence of increased glacial melt. Together, these findings reveal complex interrelationships between a critical prey resource and large-scale weather and climate processes which likely alter the accessibility of resources rather than directly affecting resource abundance. While important for understanding bald eagle reproductive dynamics in this system specifically, our results have broader implications that suggest complex interrelationships among system components
Human observers differ in ability to perceive insect diversity
Human perception of biological variation is an important and understudied issue in the conservation and management of natural resources. Here, we took a novel approach by asking 1152 participants, primarily college biology students, to score examples of insect mimicry by the number of distinct kinds of animals they saw. Latent class analysis successfully separated participants based on their accuracy of perception as well as demographic information and opinions about biodiversity. Contrary to expectations, factors such as childhood experience (growing up in urban, suburban or rural areas) did not affect the ability to see biodiversity as much as political views (location on a spectrum from liberal to conservative) or the position that biodiversity is important for the health of the environment. We conclude that research into effective measures of biological education should consider the connection between personal views and perceptions of natural variation
Quantum nondemolition detection of a propagating microwave photon
The ability to nondestructively detect the presence of a single, traveling
photon has been a long-standing goal in optics, with applications in quantum
information and measurement. Realising such a detector is complicated by the
fact that photon-photon interactions are typically very weak. At microwave
frequencies, very strong effective photon-photon interactions in a waveguide
have recently been demonstrated. Here we show how this type of interaction can
be used to realize a quantum nondemolition measurement of a single propagating
microwave photon. The scheme we propose uses a chain of solid-state 3-level
systems (transmons), cascaded through circulators which suppress photon
backscattering. Our theoretical analysis shows that microwave-photon detection
with fidelity around 90% can be realized with existing technologies
Movement and Countermovement Dynamics Between the Religious Right and LGB Community Arising from Colorado’s Amendment 2
This sample of the case study of Equality Colorado will demonstrate how counter movements and litigation may limit and change how an organization surrounding a social movement acts. Colorado for Family Values helped pass Colorado’s Amendment 2 in 1992, which limited any present and future anti-discrimination legislation that would protect sexuality as a class. This ballot initiative passed by 53% of Colorado voters, and other states like Idaho and Oregon attempted to replicate this type of initiative. Amendment 2 challenged the LGB community and compelled the movement to collectively respond to the religious right with coalitions, pooled resources, and litigation. Equality Colorado, established in 1992, will exemplify how a social movement could respond to prejudicial legislation. One of Equality Colorado’s primary tactics was to reframe religion as inclusive of gay rights. It did not cede religion entirely to its opponents and attempted to delegitimize them by labeling them “radical right” as opposed to the more popular term “religious right” or “Christian Conservatives”. Additionally, Equality Colorado tried to compensate for the downsides of litigation by “translating” the legal terms to the general public and connecting litigators with the broader movement
Using Item Response Theory to Improve Locally-Constructed Multiple Choice Tests: Measuring Knowledge Gains and Curricular Effectiveness
Current science education reform efforts emphasize teaching K-12 science using hands-on, inquiry activities. For maximum learning and probability of implementation among inservice teachers, these strategies must be modeled in college science courses for preservice teachers. About a decade ago, Morehead State University revised their science content courses to follow an inquiry approach. As part of the courses’ assessment, a locally-made, diagnostic pre- and post-test was prepared. The main purpose of this “ex post facto” study was to demonstrate how concepts from Item Response Theory can be used to detect and remove psychometrically faulty items, and how the remaining items can be used by teachers to determine science learning gains in an inquiry-based physical science course that implemented two different curricula, “Physics and Everyday Thinking” and “Interactions in Physical Science”
In Situ Surface Voltage Measurements of Dielectrics Under Electron Beam Irradiation
New instrumentation has been developed for non-contact, in vacuo measurements of the electron beam-induced surface voltage as a function of time and position for non-conductive spacecraft materials in a simulated space environment. Used in conjunction with the capabilities of an existing ultrahigh vacuum electron emission analysis chamber, the new instrumentation facilitates measurements of charge accumulation, bulk resistivity, effects of charge depletion and accumulation on yield measurements, electron induced electrostatic breakdown potentials, radiation induced conductivity effects, and the radial dispersion of surface voltage. The novel system uses two movable capacitive sensor electrodes that can be swept across the sample to measure surface charge distributions on samples, using a non-contact method that does not dissipate sample charge. Design details, calibration and characterization measurements of the system are presented, for a surface voltage range from30 kV, voltage resolution \u3c1 \u3eV, and spatial resolutio
A Novel Educational Module to Teach Neural Circuits for College and High School Students: NGSS-Neurons, Genetics, and Selective Stimulations
This report introduces various approaches to target defined neural pathways for stimulation and to address the effect of particular neural circuits on behavior in a model animal, the fruit fly (Drosophila melanogaster). The objective of this novel educational module described can be used to explain and address principle concepts in neurobiology for high school and college level students. A goal of neurobiology is to show how neural circuit activity controls corresponding behavior in animals. The fruit fly model system provides powerful genetic tools, such as the UAS-Gal4 system, to manipulate expression of non-native proteins in various populations of defined neurons: glutamergic, serotonergic, GABAergic, and cholinergic. The exhibited behaviors in the examples we provide allows teachers and students to address questions from behaviors to details at a cellular level. We provided example sets of data, obtained in a research lab, as well as ideas on ways to present data for participants and instructors. The optogenetic tool, channelrhodpsin 2 (ChR2), is employed to increase the activity of each population of neurons in a spatiotemporal controlled manner in behaving larvae and adult flies. Various behavioral assays are used to observe the effect of a specific neuron population activation on crawling behavior in larvae and climbing behavior in adult flies. Participants using this module become acquainted with the actions of different neurotransmitters in the nervous system. A pre- and post- assessment survey on the content is provided for teachers, as templates, to address learning of content and concepts
In Situ Surface Voltage Measurements of Dielectrics Under Electron Beam Irradiation
New instrumentation has been developed for non- contact, in vacuo measurements of the electron beam-induced surface voltage as a function of time and position for non- conductive spacecraft materials in a simulated space environment. The novel compact system uses two movable capacitive sensor electrodes to measure surface charge distributions on samples, using a non-contact method that has little effect on charge dissipation from sample. Design details, calibration and characterization measurements of the system are presented, with \u3c1 V to \u3e30 kV surface voltage range, \u3c0.5 V voltage resolution, and \u3c1.5 mm spatial resolution. Used in conjunction with the capabilities of an existing ultrahigh vacuum electron emission test chamber, the new instrumentation facilitates measurements of charge accumulation, bulk resistivity, effects of charge depletion and accumulation on yield measurements, electron induced electrostatic breakdown potentials, radiation induced conductivity effects, and the radial dispersion of surface voltage.
Three types of measurements of surface voltage for polyimide (Kapton HNTM) serve to illustrate the research capabilities of the new system: (i) accumulation using a pulsed electron beam, while periodically measuring the surface voltage; (ii) post charging, as deposited charge dissipated to a grounded substrate; and (iii). the evolution of spatial profile resulting from an incident Gaussian beam. Theoretical models for sample charging and discharge are outlined to predict the time, temperature, and electric field dependence of the sample’s net surface voltage
STRATEGIC GEOGRAPHIC POSITIONING OF SEA LEVEL GAUGES TO AID IN EARLY DETECTION OF TSUNAMIS IN THE INTRA-AMERICAS SEA
The potential impact of past Caribbean tsunamis generated by earthquakes and/or massive submarine slides/slumps, as well as the tsunamigenic potential and population distribution within the Intra-Americas Sea (IAS) is examined to help define the optimal location for coastal sea level gauges intended to serve as elements of a regional tsunami warning system. The goal of this study is to identify the minimum number of sea level gauge locations to aid in tsunami detection and provide the most warning time to the largest number of people. We identified 12 initial, prioritized locations for coastal sea level gauge installation. Our study area approximately encompasses 7oN, 59oW to 36oN, 98oW. The results of this systematic approach to assess priority locations for coastal sea level gauges will assist in developing a tsunami warning system (TWS) for the IAS by the National Oceanic and Atmospheric Administration (NOAA) and the Regional Sub-Commission for the Caribbean and Adjacent Regions (IOCARIBE-GOOS)
A Candidate Young Massive Planet in Orbit around the Classical T Tauri Star CI Tau
The ~2 Myr old classical T Tauri star CI Tau shows periodic variability in
its radial velocity (RV) variations measured at infrared (IR) and optical
wavelengths. We find that these observations are consistent with a massive
planet in a ~9-day period orbit. These results are based on 71 IR RV
measurements of this system obtained over 5 years, and on 26 optical RV
measurements obtained over 9 years. CI Tau was also observed photometrically in
the optical on 34 nights over ~one month in 2012. The optical RV data alone are
inadequate to identify an orbital period, likely the result of star spot and
activity induced noise for this relatively small dataset. The infrared RV
measurements reveal significant periodicity at ~9 days. In addition, the full
set of optical and IR RV measurements taken together phase coherently and with
equal amplitudes to the ~9 day period. Periodic radial velocity signals can in
principle be produced by cool spots, hot spots, and reflection of the stellar
spectrum off the inner disk, in addition to resulting from a planetary
companion. We have considered each of these and find the planet hypothesis most
consistent with the data. The radial velocity amplitude yields an Msin(i) of
~8.1 M_Jup; in conjunction with a 1.3 mm continuum emission measurement of the
circumstellar disk inclination from the literature, we find a planet mass of
~11.3 M_Jup, assuming alignment of the planetary orbit with the disk.Comment: 61 pages, 13 figures, accepted for publication in The Astrophysical
Journa
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