Flexible Pool Research Articles

Capturing the Benefits of Autonomous Vehicles in Ride Hailing: The Role of Market Configuration

We develop an economic model of autonomous vehicle (AV) ride-hailing markets, in which uncertain aggregate demand is served with a combination of a fixed fleet of AVs and a flexible pool of human drivers (HVs). Dispatch efficiencies increase with scale because of density effects. We analyze market outcomes in this setting under four market configurations, defined by two dispatch platform structures (common platform versus independent platforms) and two levels of supply competition (monopoly AV versus competitive AV). A key result of our analysis is that the lower cost of AVs does not necessarily translate into lower prices; the price impact of AVs is ambiguous and depends critically on both the dispatch platform structure and the level of AV supply competition. In the extreme case, we show that if AVs and HVs operate on independent dispatch platforms, there is a monopoly AV supplier, and labor supply elasticity is sufficiently high, then prices are even higher than in a pure-HV market. Indeed, to guarantee consistently lower prices (relative to a pure HV market) in all scenarios and under all supply and density elasticities, a common dispatch platform between AVs and HVs is required. Furthermore, competitive AVs lead to lower prices than monopoly AVs in every such scenario. Our results illustrate the critical role that market configuration plays in realizing potential welfare gains from AVs. This paper was accepted by Omar Besbes, revenue management and market analytics. Supplemental Material: The online appendix and data files are available at https://doi.org/10.1287/mnsc.2020.03112 .

Neuromesodermal Progenitors: A Basis for Robust Axial Patterning in Development and Evolution.

During early development the vertebrate embryo elongates through a combination of tissue shape change, growth and progenitor cell expansion across multiple regions of the body axis. How these events are coordinated across the length of the embryo to generate a well-proportioned body axis is unknown. Understanding the multi-tissue interplay of morphogenesis, growth and cell fate specification is essential for us to gain a complete understanding how diverse body plans have evolved in a robust manner. Within the posterior region of the embryo, a population of bipotent neuromesodermal progenitors generate both spinal cord and paraxial mesoderm derivatives during the elongation of the vertebrate body. Here we summarize recent data comparing neuromesodermal lineage and their underlying gene-regulatory networks between species and through development. We find that the common characteristic underlying this population is a competence to generate posterior neural and paraxial mesoderm cells, with a conserved Wnt/FGF and Sox2/T/Tbx6 regulatory network. We propose the hypothesis that by maintaining a population of multi-germ layer competent progenitors at the posterior aspect of the embryo, a flexible pool of progenitors is maintained whose contribution to the elongating body axis varies as a consequence of the relative growth rates occurring within anterior and posterior regions of the body axis. We discuss how this capacity for variation in the proportions and rates of NM specification might have been important allowing for alterations in the timing of embryo growth during evolution.

Service Quality in the Gig Economy: Empirical Evidence about Driving Quality at Uber

Online marketplaces have adopted new mechanisms for quality control that can accommodate a flexible pool of providers, with unclear effects on overall service quality. We focus on ride-hailing: pre-screening, which prevailed in taxi markets, has been diminished in favor of automated quality measurement, incentives, and nudges. Using telemetry data, an objective measure of quality, we show that UberX drivers perform better than UberTaxi drivers. We then explore whether the difference is driven by incentives, nudges, and information. Drivers respond to user preferences and to nudges, such as notifications due to low ratings. Informing drivers about their past behavior improves quality, especially for low-performing drivers.

Identifying Flexible Pool Pumps Suitable for Distributed Demand Response Schemes

Demand response will be an important tool as non-dispatchable generation is added to the grid. Swimming pool filtration pumps are a promising appliance for the grid operator to control because, unlike air conditioners, their time of operation can be shifted by a day without affecting their primary role. Although many customers set and forget the timer settings, this paper studies smart meter data and demonstrates that many change the settings frequently. A “care index” is proposed that quantifies how much a customer appears to care about the precise timing of pump operation, which indicates how willing they are likely to be to relinquish control to the grid operator.

Establishment of flexible nurses pool for disaster assistance and its application in Jiuzhaigou earthquake

Objective To explore the application effects of the flexible nurses pool for disaster assistance in disaster assistance. Methods A hospital flexible nurses pool for disaster assistance was constructed: the disaster assistance members based on nurses of emergency department were selected as the first echelon; the disaster nursing reserves composed of new undergraduate nurses were trained in rotation for three years as the second echelon; students of the ability promotion class consisted of excellent backbone nurses were in the third echelon; the second line nurses on duty of all wards were selected as the fourth echelon. Nursing department transferred nurses of the pool to attend to rescue according to different demands in rescue when earthquake occurred to Jiuzhaigou. Results After earthquake occurred to Jiuzhaigou, the hospital dispatched four batches health care providers, a total of 17 people (three members from the first echelon and three members from the second echelon) , to go to disaster area and to involve in first line rescue in line with different task demands. Until the wounded were admitted to wards, there were 74 person-time based on nurses from flexible pool and emergency department participated in receiving and transferring patients in hospital. The flexible pool nurses successfully completed the rescue mission in Jiuzhaigou. Conclusions The flexible nurses pool for disaster assistance can effectively shorten the time of fight-flight reaction and treatment of the wounded in emergency rescue, promote high-efficiency operation of the disaster relief system in hospital. It is the important power of hospital for rescue. Key words: Earthquakes; Flexible nurses pool; Human resources; Disaster reserves

Life history and eco‐evolutionary dynamics in light of the gut microbiota

The recent emergence of powerful genomic tools, such as high‐throughput genomics, transcriptomics and metabolomics, combined with the study of gnotobiotic animals, have revealed overwhelming impacts of gut microbiota on the host phenotype. In addition to provide their host with metabolic functions that are not encoded in its own genome, evidence is accumulating that gut symbionts affect host traits previously thought to be solely under host genetic control, such as development and behavior. Metagenomics and metatranscriptomics studies further revealed that gut microbial communities can rapidly respond to changes in host diet or environmental conditions through changes in their structural and functional profiles, thus representing an important source of metabolic flexibility and phenotypic plasticity for the host. Hence, gut microbes appear to be an important factor affecting host ecology and evolution which is, however, not accounted for in life‐history theory, or in classic population genetics, ecological and eco‐evolutionary models. In this forum, we shed new light on life history and eco‐evolutionary dynamics by viewing these processes through the lens of host– microbiota interactions. We follow a three‐level approach. First, current knowledge on the role of gut microbiota in host physiology and behavior points out that gut symbionts can be a crucial medium of life‐history strategies. Second, the particularity of the microbiota is based on its multilayered structure, composed of both a core microbiota, under host genetic and immune control, and a flexible pool of microbes modulated by the environment, which differ in constraints on their maintenance and in their contribution to host adaptation. Finally, gut symbionts can drive the ecological and evolutionary dynamics of their host through effects on individual, population, community and ecosystem levels. In conclusion, we highlight some future perspectives for integrative studies to test hypotheses on life history and eco‐evolutionary dynamics in light of the gut microbiota.

Enabling Integrated Health and Care

Enabling Integrated Health and Care

Using Cognitive Mapping and Qualitative System Dynamics to Support Decision Making in Intellectual Disability Care

AbstractProvider organizations specializing in supporting people with intellectual disabilities (ID) are under pressure because of public policy reforms, changes in society, and increased customer expectations. The combination of all these factors makes long‐term decision making a challenge for the managers of such organizations. The majority of research examining decision making in ID service organizations has commonly studied the issue from the perspective of healthcare providers. The authors contend that the degree of success of ID support providers depends on their ability to appreciate the views and interests of service receivers and frontline workers, the most important components in the system. Having a comprehensive picture of key stakeholders' overall perspectives on problem situations can enhance managers' understanding of the behavior of a complex system they manage. The authors suggest that the combination of qualitative system dynamics modeling and cognitive mapping techniques can facilitate collaborative representation of the stakeholders' views in a way that can support decision making in complex healthcare systems. The authors illustrate the application of this combined method through a case study in one ID supports provider in the Netherlands and demonstrated the possibilities of using structured stakeholders' perspectives related to flexible pool schedule shifts, one of the key resource allocation dilemmas in the organization, for organizational decision making.

Coupling of dietary phosphorus and growth across diverse fish taxa: a meta‐analysis of experimental aquaculture studies

Imbalances in phosphorus (P) intake relative to demand negatively affect animal growth, but their consequences are less understood for vertebrates, in which bone represents a significant and potentially flexible pool of P. Flexibility in body‐P content could buffer vertebrates from the effects of imbalances between P intake and demand, reducing the likelihood of a sharp stoichiometric “knife‐edge” in the relationship between growth rate and diet‐P level. We conducted a meta‐analysis of published aquaculture experiments that tested effects of diet %P on fish growth rate (49 studies, 28 species) and body‐P content (27 of the studies in the main data set, 20 species). Our meta‐analysis revealed significant P limitation of growth, as well as significant negative effects of excess P on growth rate. Diet‐P thresholds for these effects occurred at ecologically relevant levels (optimal diet‐P of 1.2% ± 0.45%, mean ± SD, under experimental conditions of high ration). Finally, the analysis also suggested a pattern of relatively shallow relationships between growth rate and diet‐P level, coupled with surprisingly flexible body‐P content in fishes. This result is consistent with fish using flexible body‐P content (presumably mediated through bone P) to buffer imbalances between P intake and demand. Together, our results provide evidence for a relatively “dull” stoichiometric “knife‐edge” in fishes, driven in part by flexible body‐P content.

Flexible pooling in gene expression profiles: design and statistical modeling of experiments for unbiased contrasts

Pooling is an important resource in microarray gene expression experiments. Due to restrictions imposed by the statistical analysis it is widespread practice to employ a fixed pool size over the whole experiment. But this limits the efficient use of experimental material. In this paper we propose a design with flexible pool sizes for mRNA pooling which includes varying numbers of experimental units per pool. Enforcing balance between the pool sizes of every treatment level, we show the unbiasedness of the generalized least squares estimator of a contrast testing for differences in gene expression between treatments. In order to model the variability of pooled observations we include random biological effects as well as a special kind of technical error (random effect for mixtures), induced by inaccuracies in blending aliquots of mRNA from different individuals into common pools. Results for one-color arrays are also extended to two-color arrays.

An analysis of diet quality, how it controls fatty acid profiles, isotope signatures and stoichiometry in the malaria mosquito Anopheles arabiensis.

BackgroundKnowing the underlying mechanisms of mosquito ecology will ensure effective vector management and contribute to the overall goal of malaria control. Mosquito populations show a high degree of population plasticity in response to environmental variability. However, the principle factors controlling population size and fecundity are for the most part unknown. Larval habitat and diet play a crucial role in subsequent mosquito fitness. Developing the most competitive insects for sterile insect technique programmes requires a “production” orientated perspective, to deduce the most effective larval diet formulation; the information gained from this process offers us some insight into the mechanisms and processes taking place in natural native mosquito habitats.Methodology/Principal FindingsFatty acid profiles and de-novo or direct assimilation pathways, of whole-individual mosquitoes reared on a range of larval diets were determined using pyrolysis gas chromatograph/mass spectrometry. We used elemental analysis and isotope ratio mass spectrometry to measure individual-whole-body carbon, nitrogen and phosphorous values and to assess the impact of dietary quality on subsequent population stoichiometry, size, quality and isotopic signature. Diet had the greatest impact on fatty acid (FA) profiles of the mosquitoes, which exhibited a high degree of dietary routing, characteristic of generalist feeders. De-novo synthesis of a number of important FAs was observed. Mosquito C:N stoichiometry was fixed in the teneral stage. Dietary N content had significant influence on mosquito size, and P was shown to be a flexible pool which limited overall population size.Conclusions/SignificanceDirect routing of FAs was evident but there was ubiquitous de-novo synthesis suggesting mosquito larvae are competent generalist feeders capable of survival on diet with varying characteristics. It was concluded that nitrogen availability in the larval diet controlled teneral mosquito size and that teneral CN ratio is a sex- and species-specific fixed parameter. This finding has significant implications for overall mosquito competitiveness and environmental management.

Converged Infrastructure: Addressing the Efficiency Challenge

Vendors are combining computing, storage, and networking systems into one integrated IT infrastructure, promising more efficiency and flexibility than traditional silo-based approaches. There are three things that datacenter and cloud-system operators most look for in their technology: efficiency, efficiency, and efficiency. Many companies work with large amounts of bursty data, which places growing demands on their computing, storage, and networking infrastructures, which adds complexity and cost to their operations. Vendors are taking a radical approach by releasing product packages that offer customers a converged infrastructure, with a preconfigured, scalable pool of computing, storage, and networking resources run by a centralized management tool. The rise of cloud computing- which requires a flexible pool of resources-is a major force driving demand for and development of converged-infrastructure systems. However, the new approach may not appeal to all users and must still overcome several obstacles before being widely adopted.

Patterns and architecture of genomic islands in marine bacteria

BackgroundGenomic Islands (GIs) have key roles since they modulate the structure and size of bacterial genomes displaying a diverse set of laterally transferred genes. Despite their importance, GIs in marine bacterial genomes have not been explored systematically to uncover possible trends and to analyze their putative ecological significance.ResultsWe carried out a comprehensive analysis of GIs in 70 selected marine bacterial genomes detected with IslandViewer to explore the distribution, patterns and functional gene content in these genomic regions. We detected 438 GIs containing a total of 8152 genes. GI number per genome was strongly and positively correlated with the total GI size. In 50% of the genomes analyzed the GIs accounted for approximately 3% of the genome length, with a maximum of 12%. Interestingly, we found transposases particularly enriched within Alphaproteobacteria GIs, and site-specific recombinases in Gammaproteobacteria GIs. We described specific Homologous Recombination GIs (HR-GIs) in several genera of marine Bacteroidetes and in Shewanella strains among others. In these HR-GIs, we recurrently found conserved genes such as the β-subunit of DNA-directed RNA polymerase, regulatory sigma factors, the elongation factor Tu and ribosomal protein genes typically associated with the core genome.ConclusionsOur results indicate that horizontal gene transfer mediated by phages, plasmids and other mobile genetic elements, and HR by site-specific recombinases play important roles in the mobility of clusters of genes between taxa and within closely related genomes, modulating the flexible pool of the genome. Our findings suggest that GIs may increase bacterial fitness under environmental changing conditions by acquiring novel foreign genes and/or modifying gene transcription and/or transduction.

A resource shared is a resource not wasted — flexible resourcing!

Many projects have to cope with changes in demands and scope throughout their lifecycle. This particularly applies in the pharmaceutical industry due to the very nature of clinical trial data reporting. How often do we hear the phrase, 'the goal posts have moved' and with this, peaks and troughs accordingly. Add in other projects going through similar scenarios, competing for the same resources, and we end up with many disgruntled Lead Programmers! A solution employed by Roche is a resourcing model that mitigates the issues that arise from the described scenarios, adopting a resource model that utilizes core and flexible resources in different manners. There are many benefits from centralising a flexible pool of resources while having core resources continually assigned on the project.

Integrating children's health services: evaluation of a national demonstration project.

Increasingly, the public and private sectors are turning to "service integration" efforts to reduce, if not eliminate, barriers to needed care created by categorical programs. In 1991, the Robert Wood Johnson Foundation established a new national demonstration project, called the Child Health Initiative, intended to test the feasibility of developing mechanisms at the community level to coordinate the delivery of health services and to pay for those services through a flexible pool of previously categorical funds. This article presents the findings of an independent evaluation of the Child Health Initiative. The evaluation utilized a combination of qualitative methods to assess and describe the experiences of the communities as they developed and implemented integrated health services. It used a repeated measures design involving two site visits and interim telephone interviews, as well as review of documents. Overall, the demonstration project achieved mixed success. Both care coordination and the production of community health report cards were found to be achievable within the relatively short life of the foundation grant. However, many sites experienced significant delays in the production of report cards and implementing care coordination plans because the sites largely did not benefit from the successful models already in existence. Little clear progress was made in implementing the decategorization component of the project. Sites experienced difficulties due to lack of previous experience with this new undertaking, the inability to secure active cooperation from local, state, and federal agencies, the relatively short duration of the project, and other factors. A number of lessons were learned from this project that may be useful in future decategorization experiments, including (1) a clear understanding of the concept and its applications among all parties is essential, (2) high-level political commitments to the effort are needed between all levels of government, (3) adequate technical assistance should be provided to surmount technical considerations in establishing a workable approach to decategorization, and (4) decategorization and service integration efforts should focus on both the health and social sectors.

Decategorizing health services: interim findings from the Robert Wood Johnson Foundation's Child Health Initiative.

Although results from the evaluation are preliminary thus far, certain tentative conclusions can be reached. First, both care coordination on a small scale and the production of community health report cards are achievable within the relatively short life of a foundation grant. Moreover, both efforts can result in tangible improvements for children and their families. Report cards associated with the initiative have made children's issues more prominent and appear to have led many community leaders to focus greater attention on children's needs. Likewise, many of the care coordination systems developed under the initiative have produced real change for children and their families by guiding them to needed health care and other services. It is important, however, to keep these accomplishments in perspective. While of significant benefit to demonstration communities, the monitoring and care coordination components of this initiative are not unique. A large number of communities have adopted monitoring and reporting programs in recent years. Similarly, care coordination efforts are well established in many communities. What is unique about the RWJF initiative is its attempt at decategorization, and much less progress has been demonstrated for this component. The less-than-hoped-for progress in implementing decategorization at the original sites appears to be the product of a number of interrelated factors. These include an absence of existing models and appropriate technical assistance; political difficulties in gaining cooperation from multiple local agencies involved in service provision; limited progress in establishing needed connections with the state and federal agencies that have authority over categorical programs; and difficulties in implementing major programatic changes when the health care system itself is undergoing rapid change. In combination, these barriers have proven to be largely insurmountable for the originally funded sites, although it is too early in the project to determine which of these factors is predominantly responsible for the lack of success. Whether the newer sites can learn from the experience of the first group and adapt strategies to overcome the multiple hurdles involved remains to be seen. Decategorization is a tool that has the potential to rationalize a fragmented service system by facilitating the coordination of services, especially for children and families with multiple needs. The need for decategorization of funds will not disappear, even if the federal government chooses to combine more of its grant programs to the states into block grants.(ABSTRACT TRUNCATED AT 400 WORDS)

Structuring of a postspring phytoplankton community by manipulation of trophic interactions

To study the effects of grazing on a natural post-spring phytoplankton community a land-based mesocosm experiment was performed during late 1988 (7–18 June). 300-1 polyethylene cylinders, immersed in a flexible pool for temperature regulation, were filled with a plankton community filtered through a 90-μm nylon net. In duplicate cylinders, the ambient copepod concentration (mainly an Acartia sp.), five times the ambient concentration, ambient concentration + medusae of the scyphozoan Aurelia aurita (L.) and ambient concentration + mussels ( Mytilus edulis L.) were added. Nutrients were added throughout the experimental period to keep the concentrations at 5 μM nitrate, 0.5 μM phosphate and 10 μM silica. Chl a, nutrients and densities of phytoplankton, ciliates and copepods were measured throughout the experiment. We observed that the diatoms remaining from the spring bloom could, with small additions of nutrients, outgrow their grazers. Only a small reduction in copepod grazing pressure through medusae predation on copepods was required for an even stronger growth and dominance by diatoms. This pattern of development could be broken by an increase in Acartia sp. biomass. An initial addition of five times the natural concentration of Acartia sp. led to a rapid growth of monads, < 3 μm, which constituted almost 100% of the biomass after 3 days. When Acartia sp. decreased in biomass, diatoms and cryptomonads became dominant. As the small naked ciliate Urotricha sp. had already been eliminated by the initially abundant copepods in the cylinders where the copepod concentration was five times the ambient concentration, there were few grazers left to make use of the ample food supply. Urotricha sp. could possibly control the < 3-μm monads if not or only moderately predated by Acartia sp., indicated by the lower increase in monad biomass in the cylinders where mussels or medusae were added. M. edulis was capable of grazing down all phytoplankton species to very low densities, except monads < 3 μm, in spite of nutrient additions, indicating a possible nonspecies-selective control of phytoplankton abudance by benthic filter-feeders in eutrophicated areas.

Analytical method for solving fluid-structure interactions in BWR pressure suppression pool

An analytical method is developed for solving the fluid-structure interactions (FSI) associated with hydraulic transients in the BWR pressure suppression pool during a hypothetical loss-of-coolant accident. The present method assumes inviscid and infinitesimal motion of pool water for which the governing fluid-dynamic equation reduces to a linear wave equation with inhomogeneous boundary conditions of flexible pool boundaries. The present method is applied to quantitative evaluation of the FSI effect on test data obtained from a large scale pressure suppression test which was performed to investigate the pressure oscillations in the pool induced by unstationary steam condensation.