590 research outputs found

    Gems: Objects of aesthetic beauty and scientific curiosity

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    This article does not have an abstract

    Heats of Formation of Solid Solutions of CsCl with CsBr

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    1008-100

    Robust scheduling practices in the U.S. airline industry: Costs, returns, and inefficiencies

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    Airlines use robust scheduling to mitigate the impact of unforeseeable disruptions on profits. We examine how effectively three common practices—flexibility to swap aircraft, flexibility to reassign gates, and scheduled aircraft downtime—accomplish this goal. We first estimate a multiple-input, multiple-outcome production frontier, which defines the attainable set of outcomes from given inputs. We then recover unobserved input costs and calculate how expenditure on inputs affects outcomes and revenues. We find that the per-dollar return from expenditure on gates, or more effective management of existing gate capacity, is three times larger than the per-dollar returns from other inputs. Next, we use the estimated trade-offs faced by carriers along the frontier to measure the value to carriers of reducing delays. Finally, we calculate the improvement in carriers’ outcomes and profits if their operational inefficiencies are eliminated. On average, we estimate that operational inefficiencies cost carriers about $1.7 billion in revenue annually

    Some illustrations of the optical behaviour of iridescent calcite

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    The paper reproduces illustrations of various optical effects displayed by twinning layers in iridescent calcite. Brief descriptive notes are appended

    Thermo-optic behaviour of silicon carbide

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    The infra-red absorption spectrum of potassium chlorate crystals: Part I

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    The infra-red transmission through the 001 face of a single crystal of potassium chlorate reveals, besides a broad absorption band in the range 9·2 μ to 12 μ , a second and narrower band with its maximum at 5·3 μ . The former band can be explained as due to the infra-red activity of the vibration frequencies ν1 (930 cm.-1) and ν2 (975 cm.-1) of the crystal also observed in the Raman effect, and their combinations with the low frequency lattice oscillations. The band at 5·3 μ may likewise be explained as due to the infra-red activity of the octaves of ν1 and ν2 and of their summational frequency

    Timely After-Sales Service and Technology Adoption: Evidence from the Off-Grid Solar Market in Uganda

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    Problem definition: Adoption and continued use of novel technologies has the potential to significantly accelerate social and economic development in emerging markets. In this paper, we examine to what extent timely after-sales service i.e., faster resolution of repair tasks impacts technology adoption. In particular, we empirically assess the impact of service wait times on the adoption of solar home systems by first-time users (i.e., adopters of the technology) in off-grid Uganda. Academic / Practical Relevance: Our study sheds light on a previously understudied driver of technology adoption - customers' post-purchase experience related to after-sales service. We also provide evidence on how negative word-of-mouth stemming from long service wait times hampers customer acquisition. Methodology: We address our research question using detailed customer-level sales and service data from a leading assembler and distributor of solar home systems in Uganda. We develop a fixed effects base specification and two instrumental variables specifications that leverage different sources of exogenous geo-spatial variation - in service task locations, weather and road quality. Results: We find that timely after-sales service experienced by existing customers is a strong driver of adoption by first-time users. A one week increase in average wait time for service decreases adoption by up to 32.4%. The relationship between wait times and adoptions is heterogeneous and depends on the types of pending service cases. We also find that the number of customers acquired through referrals from an existing customer depends on the referring customer's service wait time. This provides evidence of a strong word-of-mouth channel of information sharing. Managerial Implications: Our findings have direct implications for the customer acquisition strategies of technology firms and for technology investors in emerging markets. Our results are also relevant for policy makers who aim to harness technology to improve the socio-economic lives of people living in these regions. Importantly, we provide empirical evidence of a direct link between after-sales service and technology adoption, which is of relevance to managers outside of emerging markets as well

    Studies on soils. Part II. A microscopic study of the behaviour of the black cotton soil in salt solutions

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    On the polycrystalline forms of gypsum and their optical behaviour

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    The paper brings to notice the remarkable optical effects exhibited by a polycrystalline form of gypsum which is different from both alabaster and satin-spar in its structure. It is not a fibrous material but consists of fine rods orientated nearly parallel to the b-axis of gypsum and exhibits a ready cleavage along planes perpendicular to that axis. A source of light viewed through a plate of the material exhibits, in general, three concentric circles which are polarised in a characteristic fashion. The source itself appears as a luminous point on the second or middle circle. It is shown that these circles arise by reason of the reflection of light at the boundaries between the rod-like crystals composing the material, for which the name "fascicular gypsum" is accordingly proposed. A theoretical explanation of the phenomena is given and photographs of the same are reproduced. Observations on the optical behaviour of alabaster and of satin-spar are also reported
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