699 research outputs found

    Determinants of Land Use in the Densely Populated Kigezi Highlands of Southwestern Uganda

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    We use a multinominal logit model to examine the determinants of plot abandonment (unintentional fallows) and long fallows (intentional fallows) in order to propose policy interventions that lead to optimal and sustainable management of land use systems in Kigezi highlands. Household factors such as age, and post primary education positively influenced farmers' decision to abandon plots. Therefore, more fallows and abandoned terraces were common with older farmers compared to younger ones. However, farm size and household type had no significant influence on abandonment of plots. Plot variables such as slope and plot distance had the expected positive signs while soil fertility had a significant negative sign as predicted. Two types of interventions are recommended. Those aimed at highly cultivable, moderate slopes and those aimed at uncultivable and fragile areas. For the former, the probability of adoption and intensity of use of appropriate agrobased interventions is likely to be very high. The latter require specific interventions that are profitable and yet allowing farmers to keep the land under cover for a very long time. Furthermore, we recommend incentives aimed at minimizing distances to plot fields.abandoned terraces, Land use, Kigezi Highlands, multinominal logit, Land Economics/Use,

    Computational experimentation to understand C2 for Teams of Autonomous Systems and People

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    The technological capabilities of autonomous systems (AS) continue to accelerate. Although AS are replacing people in many skilled mission domains and demanding environmental circumstances, people and machines have complementary capabilities, and integrated performance by AS and people working together can be superior to that of either AS or people working alone. We refer to this increasingly important phenomenon as Teams of Autonomous Systems and People (TASP), and we identify a plethora of open, command and control (C2) research, policy and decision making questions. Computational experimentation offers unmatched yet largely unexplored potential to address C2 questions along these lines. The central problem is, this kind of C2 organization experimentation capability has yet to be developed and demonstrated in the TASP domain. This is where our ongoing research project begins to make an important contribution. In this article, we motivate and introduce such TASP research, and we provide an overview of the computational environment used to experiment on TASP C2 organizations and phenomena. We summarize in turn the research method. Key results follow, and we conclude then by summarizing our agenda for continued research along these lines.Consortium for Robotics and Unmanned Systems Education and Research (CRUSER)Consortium for Robotics and Unmanned Systems Education and Research (CRUSER)Approved for public release; distribution is unlimited

    Development of a high temperature battery final report

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    Development of battery with lithium-magnesium alloy anode, molten cuprous chloride cathode, and zeolite separator cells and cupric oxide cathode and porous glass separator cell

    Curriculum Materials for Elementary Reading: Shackles and Scaffolds for Four Beginning Teachers

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    The purpose of this longitudinal study was to learn how beginning elementary teachers understood and used curriculum materials for teaching reading, and how, in turn, these materials shaped teachers\u27 instruction. We followed 4 teachers who worked in markedly different school situations and were provided a variety of curriculum materials, ranging from scripted reading programs to supplemental materials without teaching guides. Data were gathered through classroom observations, interviews, and curriculum artifacts over the teachers\u27 first 3 years on the job. Our analysis suggested that curriculum materials interacted with teachers\u27 knowledge of reading and reading instruction, and with the contexts in which they worked. As a result, curriculum materials both fostered and inhibited teachers\u27 on-the-job learning. We found that the 2 teachers with weak knowledge or more restrictive materials and environments learned the least and were least able to adapt instruction to meet the needs of their students. The 2 teachers with stronger knowledge, access to multiple materials, and support for decision making regarding materials and instructional strategies learned the most and were most able to adapt instruction. Furthermore, early experiences with specific curriculum materials had effects 2 years later on these teachers\u27 instructional practices. Implications for curriculum mandates, material selection, and professional development are discussed

    Disparities in access to musculoskeletal care: Narrowing the gap: AOA critical issues symposium

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    The current health-care system in the United States has numerous barriers to quality, accessible, and affordable musculoskeletal care for multiple subgroups of our population. These hurdles include complex cultural, educational, and socioeconomic factors. Tertiary referral centers provide a disproportionately large amount of the care for the uninsured and underinsured members of our society. These gaps in access to care for certain subgroups lead to inappropriate emergency room usage, lengthy hospitalizations, increased administrative load, lost productivity, and avoidable complications and/or deaths, which all represent a needless burden on our health-care system. Through advocacy, policy changes, workforce diversification, and practice changes, orthopaedic surgeons have a responsibility to seek solutions to improve access to quality and affordable musculoskeletal care for the communities that they serve

    Going higher in the First-order Quantifier Alternation Hierarchy on Words

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    We investigate the quantifier alternation hierarchy in first-order logic on finite words. Levels in this hierarchy are defined by counting the number of quantifier alternations in formulas. We prove that one can decide membership of a regular language to the levels BΣ2\mathcal{B}\Sigma_2 (boolean combination of formulas having only 1 alternation) and Σ3\Sigma_3 (formulas having only 2 alternations beginning with an existential block). Our proof works by considering a deeper problem, called separation, which, once solved for lower levels, allows us to solve membership for higher levels

    Mitochondrial genome of Geomydoecus aurei, a pocket-gopher louse

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    Parasitic lice demonstrate an unusual array of mitochondrial genome architectures and gene arrangements. We characterized the mitochondrial genome of Geomydoecus aurei, a chewing louse (Phthiraptera: Trichodectidae) found on pocket gophers (Rodentia: Geomyidae) using reads from both Illumina and Oxford Nanopore sequencing coupled with PCR, cloning, and Sanger sequencing to verify structure and arrangement for each chromosome. The genome consisted of 12 circular mitochondrial chromosomes ranging in size from 1,318 to 2,088 nucleotides (nt). Total genome size was 19,015 nt. All 37 genes typical of metazoans (2 rRNA genes, 22 tRNA genes, and 13 protein-coding genes) were present. An average of 26% of each chromosome was composed of non-gene sequences. Within the nongene region of each chromosome, there was a 79-nt nucleotide sequence that was identical among chromosomes and a conserved sequence with secondary structure that was always followed by a poly-T region. We hypothesize that these regions may be important in the initiation of transcription and DNA replication, respectively. The G. aurei genome shares 8 derived gene clusters with other chewing lice of mammals, but in G. aurei, genes on several chromosomes are not contiguous

    Rupture by damage accumulation in rocks

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    The deformation of rocks is associated with microcracks nucleation and propagation, i.e. damage. The accumulation of damage and its spatial localization lead to the creation of a macroscale discontinuity, so-called "fault" in geological terms, and to the failure of the material, i.e. a dramatic decrease of the mechanical properties as strength and modulus. The damage process can be studied both statically by direct observation of thin sections and dynamically by recording acoustic waves emitted by crack propagation (acoustic emission). Here we first review such observations concerning geological objects over scales ranging from the laboratory sample scale (dm) to seismically active faults (km), including cliffs and rock masses (Dm, hm). These observations reveal complex patterns in both space (fractal properties of damage structures as roughness and gouge), time (clustering, particular trends when the failure approaches) and energy domains (power-law distributions of energy release bursts). We use a numerical model based on progressive damage within an elastic interaction framework which allows us to simulate these observations. This study shows that the failure in rocks can be the result of damage accumulation
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