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This paper studies intertemporal price discrimination (IPD) with complementary products in the context of e-readers and e-books. Using individual-level data (2008–2012), I estimate a dynamic demand model for e-reader adoption and subsequent book quantity, reading format, and retailer choices in several book genres. I use the estimates to simulate a monopolist’s optimal dynamic pricing strategies when facing forward-looking consumers. The results illustrate how skimming/penetration pricing incentives for e-readers and harvesting/investing incentives for e-books interact in this novel setting. The optimal joint IPD strategy is skimming for e-readers and investing for e-books. Counterfactual results suggest that combining IPD with complementary product pricing improves firm profitability because it attenuates the limitations of each pricing approach. In a single-product IPD setting, firms’ pricing power is limited when consumers anticipate future price changes and delay purchases. Adding complementary products offers firms two pricing instruments; opposite price trajectories provide conflicting incentives for consumers, limiting intertemporal arbitrage. In a static complementary product setting, firms’ pricing power is limited when the relative elasticity between the two products is heterogeneous and conflicting among consumers. Adding IPD sorts heterogeneous consumers into different periods and reduces the need to balance across consumer types. This paper was accepted by Matthew Shum, marketing.

Urban agriculture has significant potential to address food security and nutritional challenges in cities. However, water access for urban food production poses a major challenge in the face of climate change and growing global freshwater scarcity, particularly in arid and semi‐arid areas. To support sustainable urban food production, this study focuses on a hybrid urban water system that integrates two important alternative water resources: a decentralized system of rainwater harvesting (RWH) and a centralized reclaimed water system. A new spatial optimization model is developed to identify the best investment strategy for deploying these two alternative water infrastructures to expand urban food production. The model is applied to the case study in Tucson, Arizona, a semi‐arid city in U.S. Southwest, to address food deserts in the region. Results show that 72%–96% of the investment is allocated to rainwater tanks deployment across all investment scenarios, with the proportion of investment in rainwater harvesting increasing as total investment rises. However, rainwater contributes only about 18%–27% of the total food production. The results of our case study indicate that expanding the reclaimed water network is more effective for urban food production and is also more cost‐efficient compared to implementing rainwater tanks. The new model can be applied to other regions, taking into account factors such as crop types, climate, soil conditions, infrastructure configurations, costs, and other site‐specific variables. The study provides valuable insights for planning urban water systems that incorporate alternative water sources under different investment scenarios. Key Points A hybrid urban water system involving decentralized system of rainwater harvesting and centralized system of reclaimed water is optimized A new spatial optimization model is developed for optimally deploying two alternative water infrastructures to expand urban food production Expanding reclaimed water network is more cost efficient than applying rainwater harvesting for food production in a semi‐arid city, Tucson

In this research, a comprehensive survey of water resources management and sustainability was conducted over the Western desert of Iraq. A modeling was performed using both remote sensing and numerical analytical tools. Field measurements of hydrological and hydrogeological variables were used to assess surface and groundwater resources. The watershed modeling system was used to identify the existing ponds in the region and to determine their topographical and geometric characteristics based on the digital elevation models. In this study, an annual water harvesting rate was determined for each basin of the studied area, and the annual rate of all the ponds was about 8000 m3/km2. New prominent areas were identified in the field of water harvesting in which water can be exploited for various agricultural uses and the establishment of communities. The second part of water resources is groundwater resources where the amount of renewable and non-renewable groundwater in the region was estimated at more than 30 billion cubic meters. The maps obtained from the Geological Survey were used to identify important groundwater aquifers in the region and to prepare a table of promising areas for investment in future strategic projects. A group of preferred areas was identified as part of the medium-term investment plan for different uses and for safe extraction of groundwater around the province at an approximate annual rate of a billion cubic meter which is equal to the annual recharge rate of groundwater.

Rainwater harvesting (RWH) systems are effective in alleviating water supply shortages, while green roofs (GRs) can contribute to stormwater management, air quality improvement, thermal regulation of buildings, and biodiversity support. Despite their individual benefits, both systems are not frequently combined. This paper investigates the potential for integrating these systems through a hydrologic modeling and optimization approach, using a case study in Paris, France. The study utilized a Conceptual Interflow model (CI-model) coupled with a Water Balance (WB) model to describe the rainfall-runoff relationship of integrated green roof and rainwater harvesting (GR-RWH) systems. An NSGA-II optimization was then applied to the CI-WB model to determine the optimal tank sizing of GR-RWH systems for meeting different water demands. The results show that GR-RWH systems have water reliability (WR) values similar to those of traditional RWH systems without GR, albeit with larger tank volumes. For new buildings in Paris, a GR-RWH system with approximately 25 to 75% GR coverage meets rainwater utilization needs with low investment while also providing the added benefits of GRs.

Long-term selective fishing pressure often leads to miniaturization, smaller size, and early sexual maturity in many commercial fish species. To adapt, these species increase energy allocations toward maturation and reproduction, which can reduce population productivity and recruitment. However, how different fishing pressures affect reproductive investment and energy allocation between growth and reproduction remains unclear. In this study, we designed three size-selective harvesting strategies—large, random, and small harvests—to examine their effects on the growth and reproductive investment of marine medaka (Oryzias melastigma). We analyzed changes in length, weight, and gonad weight across different harvest times. Results showed that the “large harvest” group allocated more energy to reproduction, leading to miniaturization and earlier maturation, while the “small harvest” group focused more on growth, resulting in larger fish at the same age. This study provides experimental evidence on how size-selective harvesting alters reproductive investment in fish populations, offering valuable insights for the sustainable exploitation of fishery resources.

This paper assesses the impact of pollution on worker productivity by relating exogenous daily variations in ozone with productivity of agricultural workers as recorded under piece rate contracts. We find robust evidence that ozone levels well below federal air quality standards have a significant impact on productivity. These results suggest that, in contrast to common characterizations of environmental protection as a tax on producers, environmental protection can also be viewed as an investment in human capital, and thus a tool for promoting economic growth.

European short-rotation poplar plantations are harvested at 5–8 year rotations and produce relatively small stems (0.05–0.10 m3), which represent a major challenge when designing a cost-effective harvesting chain. Until now, the challenge has been met through whole-tree chipping, which allows mass-handling all through the harvesting chain. However, the production of higher value logs for the panel industry requires devising different solutions. This study presents a fully mechanized low-investment system using an excavator-based feller-buncher shear, a grapple skidder obtained from the conversion of a common farm tractor and an excavator-mounted grapple saw adapted to work as a makeshift slasher. The system was tested in Northwestern Italy, achieving high productivity (between 14 and 20 t fresh weight per scheduled machine hour) and low harvesting cost (between 9 and 14 € t−1 fresh weight). However, crosscutting quality needs further improvement, because almost 50% of the logs did not meet factory specifications. Solutions to solve this issue are proposed. The tested system is suitable for local small-scale operators because it can be acquired with a reasonable capital investment (400,000 €) and it is versatile enough for use in a number of alternative jobs, when the coppice harvesting season is over.

A novel harvesting interface for multiple piezoelectric transducers (PZTs) is proposed for high-voltage energy harvesting. Pre-biasing a PZT prior to its mechanical deformation increases its damping force, resulting in higher energy extraction. Unlike the conventional harvesters where a PZT-generated output is assumed to be continuous sinusoidal and output polarity is assumed to be alternating every cycle, PZT-generated output from human motion is expected to be random. Therefore, in the proposed approach, energy is invested to the PZT only when PZT deformation is detected. Upon the motion detection, energy stored at a storage capacitor (CSTOR) from earlier energy harvesting cycle is invested to pre-bias PZT, enhancing energy extraction. The harvested energy is transferred to back CSTOR for energy investment on the next cycle and then excess energy is transferred to the battery. In addition, partial electric charge extraction (PECE) is adapted to extract a partial amount of charges from the PZT every time its voltage approaches the process limit of 40 V. Simulations with 0.35 µm BCD process show 7.61× (with PECE only) and 8.38× (with PECE and energy investment) improvement compared to the conventional rectifier-based harvesting scheme Proposed harvesting interface successfully harvests energy from excitations with open-circuit voltages up to 100 V.

The article examines the current trends in the investment activity of hop farming in the main hop-producing countries. The structure of investments in fixed assets of the industry in large specialized farms in the USA (Washington State University methodology), in small farms in the USA (joint methodology of the University of Michigan and Vermont), in average farms in Europe (SIMAHOP methodology of the Slovenian Institute of Hop Research and Brewing) and in farms of the Chuvash Republic — the main hop-producing region of Russia (model CCU of the Czech Republic “Agro-Innovations”). According to the results of the study, it was revealed that the hop growers bear the greatest investment costs at the initial stage — during the construction of the hop frames and the laying of hops. Capital investments at this point account for 50-60% of all long-term investments. On average, 15% to 19% of investments are invested in the purchase of specialized machinery and equipment. From 20% to 30% is occupied by investment costs for hop harvesting points.

Global urbanization and increasing water demand make efficient water resource management crucial. This study employs Multi-Criteria Decision Making (MCDM) to evaluate smart city water management strategies. We use representative criteria, employ objective judgment, assign weights through the Analytic Hierarchy Process (AHP), and score strategies based on meeting these criteria. We find that the “Effectiveness and Risk Management” criterion carries the highest weight (15.28%), underscoring its pivotal role in strategy evaluation and robustness. Medium-weight criteria include “Resource Efficiency, Equity, and Social Considerations” (10.44%), “Integration with Existing Systems, Technological Feasibility, and Ease of Implementation” (10.10%), and “Environmental Impact” (9.84%) for ecological mitigation. “Community Engagement and Public Acceptance” (9.79%) recognizes involvement, while “Scalability and Adaptability” (9.35%) addresses changing conditions. “Return on Investment” (9.07%) and “Regulatory and Policy Alignment” (8.8%) balance financial and governance concerns. Two low-weight criteria, “Data Reliability” (8.78%) and “Long-Term Sustainability” (8.55%), stress data accuracy and sustainability. Highly weighted strategies like “Smart Metering and Monitoring, Demand Management, Behavior Change” and “Smart Irrigation Systems” are particularly effective in improving water management in smart cities. However, medium-weighted (e.g., “Educational Campaigns and Public Awareness”, “Policy and Regulation”, “Rainwater Harvesting”, “Offshore Floating Photovoltaic Systems”, “Collaboration and Partnerships”, “Graywater Recycling and Reuse”, and “Distributed Water Infrastructure”) and low-weighted (e.g., “Water Desalination”) strategies also contribute and can be combined with higher-ranked ones to create customized water management approaches for each smart city’s unique context. This research is significant because it addresses urban water resource management complexity, offers a multi-criteria approach to enhance traditional single-focused methods, evaluates water strategies in smart cities comprehensively, and provides a criteria-weight-based resource allocation framework for sustainable decisions, boosting smart city resilience. Note that results may vary based on specific smart city needs and constraints. Future studies could explore factors like climate change on water management in smart cities and consider alternative MCDM methods like TOPSIS or ELECTRE for strategy evaluation.