1,825 research outputs found

    Functorial properties of Putnam's homology theory for Smale spaces

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    We investigate functorial properties of Putnam's homology theory for Smale spaces. Our analysis shows that the addition of a conjugacy condition is necessary to ensure functoriality. Several examples are discussed that elucidate the need for our additional hypotheses. Our second main result is a natural generalization of Putnam's Pullback Lemma from shifts of finite type to non-wandering Smale spaces.Comment: Updated to agree with published versio

    High temperature radiator materials for applications in the low Earth orbital environment

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    Radiators must be constructed of materials which have high emittance in order to efficiently radiate heat from high temperature space power systems. In addition, if these radiators are to be used for applications in the low Earth orbital environment, they must not be detrimentally affected by exposure to atomic oxygen. Four materials selected as candidate radiator materials (304 stainless steel, copper, titanium-6% aluminum-4% vanadium (Ti-6%Al-4%V), and niobium-1% zirconium (Nb-1%Zr)) were surface modified by acid etching, heat treating, abrading, sputter texturing, electrochemical etching, and combinations of the above in order to improve their emittance. Combination treatment techniques with heat treating as the second treatment provided about a factor of two improvement in emittance for 304 stainless steel, Ti-6%Al-4%V, and Nb-1%Zr. A factor of three improvement in emittance occurred for discharge chamber sputter textured copper. Exposure to atomic oxygen in an RF plasma asher did not significantly change the emittance of those samples that had been heat treated as part of their texturing process. An evaluation of oxygen penetration is needed to understand how oxidation affects the mechanical properties of these materials when heat treated

    Effect of Urbanization on the Adoption of Environmental Management Systems in Canadian Agriculture

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    This study examines the extent to which farming practices have adjusted to the presence of urbanization in Canada. In particular, we compare the adoption rates for environmental management systems (EMSs) by farmers close to urbanized areas versus those in more rural, isolated regions. Using information from a national survey of 16,053 farmers, eight EMSs are considered. We find that farmers operating close to the urban milieu demonstrate strategic behavior by selecting more environmentally-friendly farm management practices to overcome social and regulatory pressures from such communities compared to those farmers that operate in rural communities.Farm Management,

    Touch Versus Tech: When Technology Functions as a Barrier or a Benefit to Service Encounters

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    Interpersonal exchanges between customers and frontline service employees increasingly involve the use of technology, such as point-of-sale terminals, tablets, and kiosks. The present research draws on role and script theories to demonstrate that customer reactions to technology-infused service exchanges depend on the presence of employee rapport. When rapport is present during the exchange, the use of technology functions as an interpersonal barrier preventing the customer from responding in kind to employee rapport-building efforts, thereby decreasing service encounter evaluations. However, during service encounters in which employees are not engaging in rapport building, technology functions as an interpersonal barrier, enabling customers to retreat from the relatively unpleasant service interaction, thereby increasing service encounter evaluations. Two analyses using J.D. Power Guest Satisfaction Index data support the barrier and beneficial effects of technology use during service encounters with and without rapport, respectively. A follow-up experiment replicates this data pattern and identifies psychological discomfort as a key process that governs the effect. For managers, the results demonstrate the inherent incompatibility of initiatives designed to encourage employee–customer rapport with those that introduce technology into frontline service exchanges

    Securing the Internet of Healthcare

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    Cybersecurity, which includes the security of information technology (IT), is critical to ensuring that society trusts, and therefore can benefit from, modern technology. Problematically, though, rarely a day goes by without a news story related to how critical data has been exposed, exfiltrated, or otherwise inappropriately used or accessed as a result of supply chain vulnerabilities. From the Russian government’s campaign to influence the 2016 U.S. presidential election to the September 2017 Equifax breach of more than 140 million Americans’ credit reports, cyber risk has become a topic of conversation in boardrooms and the White House, on Wall Street and main street. But these discussions often miss the problems replete in the expansive supply chains on which many of these products and services we depend on are built; this is particularly true in the medical device context. The problem recently made national news with the voluntary recall of more than 400,000 pacemakers that were found to be vulnerable to hackers, necessitating a firmware update. This Article explores the myriad vulnerabilities in the supply chain for medical devices, investigates existing FDA cybersecurity and privacy regulations to identify any potential governance gaps, and suggests a path forward to boost cybersecurity due diligence for manufacturers by making use of new approaches and technologies, including blockchain

    Population and Harvest Trends of Big Game and Small Game Species

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    This technical document supports the Forest Service’s requirement to assess the status of renewable natural resources as mandated by the Forest and Rangeland Renewable Resources Planning Act of 1974 (RPA). It updates past reports on national and regional trends in population and harvest estimates for species classified as big game and small game. The trends reported here were derived from State Wildlife Agency biologists and supplemented with data from the North American Breeding Bird Survey for those bird species that are commonly sought by upland game hunters. Big game populations and harvests have generally increased over the 1975-2000 period. Small game populations and harvests, particularly those associated with grassland and agricultural systems, show strong patterns of decline. However, population and harvest trends for both groups need to be interpreted with caution because: (1) not all state agencies reported both population and harvest statistics for all species that are commonly sought by recreational hunters, and (2) there were cases of inconsistent reporting at the species level within RPA reporting regions that necessitated aggregating across species. The trends documented here are consistent with trends documented in past RPA reports completed in 1989 and 1999, although those data were also qualified by the same interpretational caveats that apply to the current report. Trends observed generally among big game species were encouraging, but the continual decline in small game populations and harvest remains an important wildlife resource management issue. Until population and harvest monitoring is improved among institutions that share the stewardship responsibility for recreationally important wildlife, national and regional trends will have to be interpreted carefully

    Reading Instruction for Children who use AAC: Considerations in the Pursuit of Generalizable Results

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    Our purpose was to review evidence-based literacy instruction for children with severe speech impairment (SSI) who communicate with AAC. This review focuses on three issues important to researchers in this area: participant heterogeneity, assessment and instruction, and research design. We found 8 articles that reported attempts to teach phonological awareness and individual-word reading to a total of 26 children with SSI who used AAC. We evaluated these studies based on reporting of participant characteristics, assessment and instruction modifications, and the strength of research designs. We conclude by highlighting the need for standard assessments that can be used across studies, discussing strategies for facilitating metaanalyses, and suggesting the creation of an online database for researchers to share results on literacy instruction for this population

    Population and Harvest Trends of Big Game and Small Game Species

    Get PDF
    This technical document supports the Forest Service’s requirement to assess the status of renewable natural resources as mandated by the Forest and Rangeland Renewable Resources Planning Act of 1974 (RPA). It updates past reports on national and regional trends in population and harvest estimates for species classified as big game and small game. The trends reported here were derived from State Wildlife Agency biologists and supplemented with data from the North American Breeding Bird Survey for those bird species that are commonly sought by upland game hunters. Big game populations and harvests have generally increased over the 1975-2000 period. Small game populations and harvests, particularly those associated with grassland and agricultural systems, show strong patterns of decline. However, population and harvest trends for both groups need to be interpreted with caution because: (1) not all state agencies reported both population and harvest statistics for all species that are commonly sought by recreational hunters, and (2) there were cases of inconsistent reporting at the species level within RPA reporting regions that necessitated aggregating across species. The trends documented here are consistent with trends documented in past RPA reports completed in 1989 and 1999, although those data were also qualified by the same interpretational caveats that apply to the current report. Trends observed generally among big game species were encouraging, but the continual decline in small game populations and harvest remains an important wildlife resource management issue. Until population and harvest monitoring is improved among institutions that share the stewardship responsibility for recreationally important wildlife, national and regional trends will have to be interpreted carefully
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