2,694 research outputs found

    For Logs, For Traditional Purposes and For Food: Identification of Multiple-Use Plant Species of Northern Amazonia and an Assessment of Factors Associated with Their Distribution

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    This dissertation examines the multiplicity of uses associated with tree and palm species of the Rupununi, Southern Guyana and the factors associated with their distribution. As tropical forests continue to decline the most significant response has been to understand the implications for the carbon cycle, with the impacts on forest dwelling peoples and wildlife, inadequately addressed. Multiple-use plants, individual species which at their most critical level provide food for wildlife, non-timber forest products and are commercially logged, provide a suitable lens for appreciating additional ecosystem services that may be compromised as tropical forests decline. I completed a plant inventory in the Rupununi and drew on the traditional knowledge of Amerindians to define multiple-use plants, describe their multiplicity of uses, describe vegetation types and assess multiple-use species distribution relative to land tenure classes and herbivores. I found four classes of multiple-use plants: wildlife food and commercial timber; commercial timber and traditional uses; wildlife food and traditional uses; and, wildlife food, commercial timber and traditional uses, each representing a unique dimension of ecosystem services such plants provide. A map created with descriptions of vegetation from Amerindian hunters showed that multiple-use plants are distributed in forest types that are critical for Amerindian livelihood activities. Further, as policies towards the extraction or protection of plant species are dictated by land tenure holdings, my assessments showed that strategies aimed at sustaining ecosystem services provided by multiple-use plants must consider the ideals for resource management within tenure classes. As expected, the distribution of a key disperser of multiple-use plants fruits and seeds - spider monkeys (Ateles paniscus), was closely related to the distribution of their food sources. My results show that land-use change impacting multiple-use plants will have implications for wildlife, and as a consequence traditional activities of forest dwelling peoples

    Modeling multiple human operators in the supervisory control of heterogeneous unmanned vehicles

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    In the near future, large, complex, time-critical missions, such as disaster relief, will likely require multiple unmanned vehicle (UV) operators, each controlling multiple vehicles, to combine their efforts as a team. However, is the effort of the team equal to the sum of the operator's individual efforts? To help answer this question, a discrete event simulation model of a team of human operators, each performing supervisory control of multiple unmanned vehicles, was developed. The model consists of exogenous and internal inputs, operator servers, and a task allocation mechanism that disseminates events to the operators according to the team structure and state of the system. To generate the data necessary for model building and validation, an experimental test-bed was developed where teams of three operators controlled multiple UVs by using a simulated ground control station software interface. The team structure and interarrival time of exogenous events were both varied in a 2×2 full factorial design to gather data on the impact on system performance that occurs as a result of changing both exogenous and internal inputs. From the data that was gathered, the model was able to replicate the empirical results within a 95% confidence interval for all four treatments, however more empirical data is needed to build confidence in the model's predictive ability.United States. Office of Naval ResearchUnited States. Air Force Office of Scientific Researc

    Susans Career Dilemma At MGR, LLC

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    Professionals starting their first job after graduate school want to launch a successful career. Unfortunately, some of them soon find out that performing at a high level does not always guarantee rapid promotion or success in their organization. This is a story about Susan, a highly recruited attorney, who joined an established law firm in Washington, DC, and was slow to realize that managing her boss is a critical skill needed for her survival and prosperity. Carlos, her direct supervisor and advocate of a tough love approach to management, views the effective nurturance and mentoring of new employees as his means of entr into the ranks of senior partner. Carlos and Susan are on a collision course with a potential impact on both of their careers. Susan needed to decide at the end of the case what to do to strategically manage her career

    CPU-less robotics: distributed control of biomorphs

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    Traditional robotics revolves around the microprocessor. All well-known demonstrations of sensory guided motor control, such as jugglers and mobile robots, require at least one CPU. Recently, the availability of fast CPUs have made real-time sensory-motor control possible, however, problems with high power consumption and lack of autonomy still remain. In fact, the best examples of real-time robotics are usually tethered or require large batteries. We present a new paradigm for robotics control that uses no explicit CPU. We use computational sensors that are directly interfaced with adaptive actuation units. The units perform motor control and have learning capabilities. This architecture distributes computation over the entire body of the robot, in every sensor and actuator. Clearly, this is similar to biological sensory- motor systems. Some researchers have tried to model the latter in software, again using CPUs. We demonstrate this idea in with an adaptive locomotion controller chip. The locomotory controller for walking, running, swimming and flying animals is based on a Central Pattern Generator (CPG). CPGs are modeled as systems of coupled non-linear oscillators that control muscles responsible for movement. Here we describe an adaptive CPG model, implemented in a custom VLSI chip, which is used to control an under-actuated and asymmetric robotic leg

    What Promotes healing among the wrongfully convicted? Results from a qualitative study of exonerated persons in California

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    Background: Exonerees are individuals who have been wrongfully convicted of a crime. Later found innocent and released from prison, exonerees often spend decades incarcerated. While limited, research suggests that the unique trauma of wrongful conviction has profound adverse mental health implications which challenge reintegration, well-being and healing. In this study we examined exoneree perceptions of their mental health and coping mechanisms used to support healing. Methods: We conducted a qualitative study utilizing a phenomenological approach to examine shared coping and healing mechanisms among exonerees. Twelve California exonerees participated in semi-structured interviews describing their experiences with coping and healing due to wrongful conviction. Interviews were audio recorded and transcribed, transcripts were coded with a hybrid coding scheme utilizing a thematic analysis. Results: Overall findings underscore the lifelong trauma and subsequent adverse mental well-being among wrongfully convicted exonerees, framed in association with depression, anxiety, post-traumatic stress disorder (PTSD) and hypervigilance. Three areas emerged as valuable coping mechanisms for exonerees that support a pathway toward healing: 1) Peer support and building community with other exonerees through organized meetings (convenings and healing circles); 2) Community education to build community awareness through storytelling; and 3) Advocacy engagement in the wrongful conviction movement and criminal justice reform. Conclusions: Complementing comprehensive mental health services with opportunities for peer support, advocacy, and community education through storytelling may help exonerees regain lives lost to their wrongful convictions

    Lithium in the Intermediate-Age Open Cluster, NGC 3680

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    High-dispersion spectra centered on the Li 6708 A line have been obtained for 70 potential members of the open cluster NGC 3680, with an emphasis on stars in the turnoff region. A measurable Li abundance has been derived for 53 stars, 39 of which have radial velocities and proper motions consistent with cluster membership. After being transferred to common temperature and abundance scales, previous Li estimates have been combined to generate a sample of 49 members, 40 of which bracket the cluster Li-dip. Spectroscopic elemental analysis of 8 giants and 5 turnoff stars produces [Fe/H] = -0.17 +/- 0.07 (sd) and -0.07 +/- 0.02 (sd), respectively. We also report measurements of Ca, Si and Ni which are consistent with scaled-solar ratios within the errors. Adopting [Fe/H] = -0.08 (Sect. 3.6), Y^2 isochrone comparisons lead to an age of 1.75 +/- 0.10 Gyr and an apparent modulus of (m-M) = 10.30 +/- 0.15 for the cluster, placing the center of the Li-dip at 1.35 +/- 0.03 solar masses. Among the giants, 5 of 9 cluster members are now known to have measurable Li with A(Li) near 1.0. A combined sample of dwarfs in the Hyades and Praesepe is used to delineate the Li-dip profile at 0.7 Gyr and [Fe/H] = +0.15, establishing its center at 1.42 +/- 0.02 solar masses and noting the possible existence of secondary dip on its red boundary. When evolved to the typical age of the clusters NGC 752, IC 4651 and NGC 3680, the Hyades/Praesepe Li-dip profile reproduces the observed morphology of the combined Li-dip within the CMD's of the intermediate-age clusters while implying a metallicity dependence for the central mass of the Li-dip given by Mass = (1.38 +/-0.04) + (0.4 +/- 0.2)[Fe/H]. The implications of the similarity of the Li-dichotomy among giants in NGC 752 and IC 4651 and the disagreement with the pattern among NGC 3680 giants are discussed.Comment: Latex ms. is 56 pages, including 10 figures and 4 tables. Accepted for the Astronomical Journa

    WIYN Open Cluster Study. XXXIX. Abundances in NGC 6253 from HYDRA Spectroscopy of the Li 6708 A Region

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    High-dispersion spectra of 89 potential members of the old, super-metal-rich open cluster, NGC 6253, have been obtained with the HYDRA multi-object spectrograph. Based upon radial-velocity measurements alone, 47 stars at the turnoff of the cluster color-magnitude diagram (CMD) and 18 giants are identified as potential members. Five turnoff stars exhibit evidence of binarity while proper-motion data eliminates two of the dwarfs as members. The mean cluster radial velocity from probable single-star members is -29.4 +/- 1.3 km/sec (sd). A discussion of the current estimates for the cluster reddening, derived independently of potential issues with the BV cluster photometry, lead to an adopted reddening of E(B-V) = 0.22 +/- 0.04. From equivalent width analyses of 38 probable single-star members near the CMD turnoff, the weighted average abundances are found to be [Fe/H] = +0.43 +/- 0.01, [Ni/H] = +0.53 +/- 0.02 and [Si/H] = +0.43 (+0.03,-0.04), where the errors refer to the standard errors of the weighted mean. Weak evidence is found for a possible decline in metallicity with increasing luminosity among stars at the turnoff. We discuss the possibility that our turnoff stars have been affected by microscopic diffusion. For 15 probable single-star members among the giants, spectrum synthesis leads to abundances of +0.46 (+0.02,-0.03) for [Fe/H]. While less than half the age of NGC 6791, NGC 6253 is at least as metal-rich and, within the uncertainties, exhibits the same general abundance pattern as that typified by super-metal-rich dwarfs of the galactic bulge.Comment: 5 Tables, 9 figures, 45 page

    WIYN Open Cluster Study. LXIII. Abundance in the Super-Metal-Rich Open Cluster NGC 6253 from Hydra Sprectroscopy of the 7774 Ã… Oxygen Triplet Region

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    We present a spectroscopic abundance analysis of the old, super-metal-rich open cluster NGC 6253, with emphasis on its O abundance. High-dispersion, 7774 Å O i triplet region spectra of 47 stars were obtained using Hydra II on the CTIO Blanco 4 m. Radial velocity analysis confirms 39 stars consistent with single star membership, primarily at the turnoff. Thirty-six of these are included in our abundance analysis. Our differential analysis relative to the Sun yields primarily scaled-solar values, with weighted cluster averages of [O/H] = +0.440 ± 0.020, [Fe/H] = +0.445 ± 0.014, [Al/H] = +0.487 ± 0.020, [Si/H] = +0.504 ± 0.018, and [Ni/H] = +0.702 ± 0.018 (where the errors are σμ{{\sigma }_{\mu }}). We discuss possible origins for the three known super-metal-rich clusters based upon their abundance patterns, Galactic locations, and space motions. The abundance patterns of NGC 6253 are very similar to those of NGC 6791 and NGC 6583. With the possible exception of oxygen, the abundances of these clusters are all close to scaled-solar, and they are similar to patterns seen in metal-rich disk dwarfs and giants. However, they also seem to differ from those of metal-rich bulge stars. We demonstrate that NGC 6253 is unusually oxygen rich (in [O/H]) for its 3.3 Gyr age. While we find [O/Fe] to be scaled-solar for NGC 6253, the more recently reported values for NGC 6791 show a large variation, from values close to scaled-solar down to values at least a factor of two below scaled-solar. We discuss the possibility that the scaled-solar [O/Fe] abundances of NGC 6253 and NGC 6791 might reflect a flattening of the Galactic [O/Fe] versus [Fe/H] relationship. This possibility may be consistent with disk star abundance data, which show an apparent "floor" at [O/Fe] ∼−0.1\sim -0.1 for [Fe/H] >  0\gt \;0, and with chemical evolution model results, which may predict such a flattening due to a decrease in supernova Fe yields at super-solar-metallicities. Orbit solutions for NGC 6791 allow that it may have formed in the inner disk and was then kicked out, but the origins of the other two much younger clusters remain mysterious. We re-evaluate the age of NGC 6583 in view of the evidence that the cluster is super-metal-rich, and confirm a probable age less than 1 Gyr (best range: 500–900 Myr). We also argue that it is unlikely the cluster is more than 3 kpc away (best range: 2–3 kpc) if the apparent turnoff, main sequence, and giants are all cluster members
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