Gems: Objects of aesthetic beauty and scientific curiosity

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Heats of Formation of Solid Solutions of CsCl with CsBr

1008-100

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

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

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

This article does not have an abstract

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

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

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

The Digital Lives of the Poor: Entertainment Traps and Information Isolation

Smartphones have enabled the delivery of life-improving information services to base-of-the-pyramid (BOP) consumers. However, little is known about how the poor interact with the digital world. Through a novel app we developed to investigate real-time smartphone usage, we identify an unnoticed barrier to digital information access by the poor—data shortages. By analyzing over 9.4 million minutes of smartphone usage data from 929 residents of a Mumbai settlement, we find that entertainment consumes 61% of their phone time. Our data reveal that under universally adopted monthly data plans, low-income individuals binge on YouTube and social media, resulting in data shortages and information isolation in the late-plan period. We offer a practical operational solution to this problem—shorter data-replenishment cycles—which serve as a commitment device to curb binge usage. We randomly assign participants to a “capped plan”—with daily data usage caps—or a standard (monthly) plan. Assignment to the capped plan increases late-plan access of invites to health camps sent via WhatsApp, increases attendance at these in-person camps by 27%, and reduces social media binge usage. Most participants (particularly those with low self-control and high fear of missing out) prefer the capped plan, even when costlier—clearly signaling demand. Because capped plans are inherently cheaper to provide, offering them could enable providers to increase BOP customer value and expand access. Our results suggest an opportunity to amplify the impact of life-improving services targeted at the poor by leveraging users’ interactions with smartphone technology

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

This article does not have an abstract