A Quantum Internet Architecture

Entangled quantum communication is advancing rapidly, with laboratory and metropolitan testbeds under development, but to date there is no unifying Quantum Internet architecture. We propose a Quantum Internet architecture centered around the Quantum Recursive Network Architecture (QRNA), using RuleSet-based connections established using a two-pass connection setup. Scalability and internetworking (for both technological and administrative boundaries) are achieved using recursion in naming and connection control. In the near term, this architecture will support end-to-end, two-party entanglement on minimal hardware, and it will extend smoothly to multi-party entanglement and the use of quantum error correction on advanced hardware in the future. For a network internal gateway protocol, we recommend (but do not require) qDijkstra with seconds per Bell pair as link cost for routing; the external gateway protocol is designed to build recursively. The strength of our architecture is shown by assessing extensibility and demonstrating how robust protocol operation can be confirmed using the RuleSet paradigm.Comment: 17 pages, 7 numbered figure

QuISP: a Quantum Internet Simulation Package

We present an event-driven simulation package called QuISP for large-scale quantum networks built on top of the OMNeT++ discrete event simulation framework. Although the behavior of quantum networking devices have been revealed by recent research, it is still an open question how they will work in networks of a practical size. QuISP is designed to simulate large-scale quantum networks to investigate their behavior under realistic, noisy and heterogeneous configurations. The protocol architecture we propose enables studies of different choices for error management and other key decisions. Our confidence in the simulator is supported by comparing its output to analytic results for a small network. A key reason for simulation is to look for emergent behavior when large numbers of individually characterized devices are combined. QuISP can handle thousands of qubits in dozens of nodes on a laptop computer, preparing for full Quantum Internet simulation. This simulator promotes the development of protocols for larger and more complex quantum networks.Comment: 17 pages, 12 figure

Research priorities for freshwater mussel conservation assessment

Freshwater mussels are declining globally, and effective conservation requires prioritizing research and actions to identify and mitigate threats impacting mussel species. Conservation priorities vary widely, ranging from preventing imminent extinction to maintaining abundant populations. Here, we develop a portfolio of priority research topics for freshwater mussel conservation assessment. To address these topics, we group research priorities into two categories: intrinsic or extrinsic factors. Intrinsic factors are indicators of organismal or population status, while extrinsic factors encompass environmental variables and threats. An understanding of intrinsic factors is useful in monitoring, and of extrinsic factors are important to understand ongoing and potential impacts on conservation status. This dual approach can guide conservation status assessments prior to the establishment of priority species and implementation of conservation management actions.NF-R was supported by a post-doctoral fellowship (Xunta de Galicia Plan I2C 2017-2020, 09.40.561B.444.0) from the government of the autonomous community of Galicia. BY was supported by the Ministry of Science and Higher Education (no. 0409-2016-0022). DLS was supported by the G. E. Hutchinson Chair at the Cary Institute of Ecosystem Studies. AO was supported by the Russian Foundation for Basic Research (no. 17-44-290016). SV was funded by European Investment Funds by FEDER/COMPETE/POCI- Operacional Competitiveness and Internacionalization Programme, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT-Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013. NF-R is very grateful to the University of Oklahoma Biological Survey for providing space to work in the U.S. and especially to Vaughn Lab members. Authors are very grateful to Akimasa Hattori, Allan K. Smith, Andrew Roberts, Daniel Graf, David Stagliano, David T. Zanatta, Dirk Van Damme, Ekaterina Konopleva, Emilie Blevins, Ethan Nedeau, Frankie Thielen, Gregory Cope, Heinrich Vicentini, Hugh Jones, Htilya Sereflisan, Ilya Vikhrev, John Pfeiffer, Karen Mock, Mary Seddon, Katharina Stockl, Katarzyna Zajac, Kengo Ito, Marie Capoulade, Marko Kangas, Michael Lange, Mike Davis, Pirkko-Liisa Luhta, Sarina Jepsen, Somsak Panha, Stephen McMurray, G. Thomas Watters, Wendell R. Haag, and Yoko Inui for their valuable contribution in the initial selection and description of extrinsic and intrinsic factors. We also wish to thank Dr. Amanda Bates, Chase Smith, and two anonymous reviewers for comments on earlier drafts of this manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government

The significance of meandering channel to habitat diversity and fish assemblage: a case study in the Shibetsu River, northern Japan

This study examined the structure and function of habitats for fish, the contribution to fish populations, and the effects of channel modification on habitats and fish populations in the lowland meandering Shibetsu River, northern Japan. Electrofishing and environmental measurements were conducted in bank areas of habitats constituting natural meandering and modified reaches. All types of habitats in a meandering reach highly contributed to the fish population(s). In particular, the contributions of lateral and wood habitats to fish populations were generally high, despite the low spatial extent of these habitats. The modified reach was simplified and had fewer types of habitats with uniform currents, and there was a low abundance of most fish within these habitats. Abundance of each fish group (taxa) was negatively affected by the changes in the habitats and/or channel shortening (i.e., decrease in the absolute abundance of habitat) due to river modification, which was implemented during 1950-1978. This study suggests that the recovery of all the habitat types is important in meander restoration and that the changes in habitat types and abundance should be examined in monitoring meander restoration and channel shortening

Time Series Changes in Fish Assemblages and Habitat Structures Caused by Partial Check Dam Removal

Despite a steep increase in dam removal projects, there are few studies on the biophysical responses to dam removal. In this study, we evaluated the short-term (1.5 years) and long-term (5.5 years) effects of partial check dam removal on fish assemblages and their habitats. First, the habitat preferences of fish were examined at a channel unit scale: pools, rapids, and side channels satisfied the seasonal habitat requirements of the fish assemblages. Partial check dam removal increased the abundance of these habitats and diversified the habitat structures owing to the sediment release from the dam; in contrast, the bedrock distinctly decreased 1.5 years after dam removal. However, 5.5 years after dam removal, the bedrock proportion increased, and the habitat structures were simplified again owing to the re-transportation of sediments. Similar temporal changes were also determined through a reach-scale analysis with a change in the bed materials. Anadromous Oncorhynchus masou began to spawn and recolonize in the upstream section of the dam after the dam removal, causing similar assemblage compositions between the downstream and upstream sections. The abundance of Salvelinus malma and Noemacheilus barbatulus toni in the upstream reaches decreased over time after the dam removal. The temporal changes in the biophysical responses suggest that long-term monitoring is indispensable for the reliable evaluation of dam removal effects

Impacts of Flood Disturbance on the Dynamics of Basin-Scale Swimming Fish Migration in Mountainous Streams

This study investigated the response of sweetfish (Plecoglossus altivelis), a species that migrates dynamically throughout a river basin, to two flood events during the summer of 2020 in the Nagara River, located in the central region of Japan. By combining multiple environmental DNA (eDNA) surveys and hydrological modeling, the spatiotemporal distribution of P. altivelis throughout a mountainous river basin was captured and analyzed. The eDNA concentrations at 42 sites in the Nagara River Basin were analyzed five times from August to early October 2020. In addition, Rainfall–Runoff–Inundation model calculations were performed using 1-km resolution precipitation data as input values to analyze the magnitude of the flood disturbance at the eDNA sites. The daily specific discharge Qs (m3/s/km2) was employed as an index of the flood magnitude. The calculation period included Flood Events 1 and 2 with 52 and 38 days of precipitation reaching 1923 and 528 mm, respectively. The results of the eDNA analysis showed that, immediately after Flood Event 1, the spatial distribution of P. altivelis was unevenly distributed in the upper reaches of the Nagara River and some of its tributaries. Subsequently, the distribution expanded to the entire mainstem. The distribution of the maximum daily specific discharge suggested that the river segments with high eDNA concentrations of P. altivelis immediately after the high-magnitude flood event were those with a relatively low intensity of flood disturbance compared with those in the other connected river segments and tributaries. The results of this study indicate that the resilience of riverine communities to extreme floods is supported by the continuity and connectivity between the mainstem and its tributaries in mountainous river basins

Impacts of Flood Disturbance on the Dynamics of Basin-Scale Swimming Fish Migration in Mountainous Streams

This study investigated the response of sweetfish (Plecoglossus altivelis), a species that migrates dynamically throughout a river basin, to two flood events during the summer of 2020 in the Nagara River, located in the central region of Japan. By combining multiple environmental DNA (eDNA) surveys and hydrological modeling, the spatiotemporal distribution of P. altivelis throughout a mountainous river basin was captured and analyzed. The eDNA concentrations at 42 sites in the Nagara River Basin were analyzed five times from August to early October 2020. In addition, Rainfall–Runoff–Inundation model calculations were performed using 1-km resolution precipitation data as input values to analyze the magnitude of the flood disturbance at the eDNA sites. The daily specific discharge Qs (m3/s/km2) was employed as an index of the flood magnitude. The calculation period included Flood Events 1 and 2 with 52 and 38 days of precipitation reaching 1923 and 528 mm, respectively. The results of the eDNA analysis showed that, immediately after Flood Event 1, the spatial distribution of P. altivelis was unevenly distributed in the upper reaches of the Nagara River and some of its tributaries. Subsequently, the distribution expanded to the entire mainstem. The distribution of the maximum daily specific discharge suggested that the river segments with high eDNA concentrations of P. altivelis immediately after the high-magnitude flood event were those with a relatively low intensity of flood disturbance compared with those in the other connected river segments and tributaries. The results of this study indicate that the resilience of riverine communities to extreme floods is supported by the continuity and connectivity between the mainstem and its tributaries in mountainous river basins

Combining energetic profitability and cover effects to evaluate salmonid habitat quality

Recent studies have demonstrated that the energetic profitability (net energy intake potential; NEI potential) of a habitat, which is calculated as the gross energy gain from foraging minus the energy expenditure from swimming at a focal point, may be a useful tool for predicting the salmonid biomass. The effectiveness of the NEI potential should be tested in various systems. Even if the NEI potential is validated, its predictive accuracy and transferability could be limited if the cover habitat, which is known to be an important factor for determining salmonid abundance, is not considered. We tested whether the NEI potential is effective for predicting the salmonid biomass even in a stream with abundant cover and whether combining the NEI potential and cover effects can improve the predictability of fish biomass using a generalized linear model. Our results demonstrated that the NEI potential could generally predict the fish biomass (percent deviance explained = 79.9 %), and the model that incorporated both the NEI potential and the cover ratio improved the predictive accuracy (percent deviance explained = 88.5 %). These results suggest that energetic profitability can be an effective indicator for assessing habitat quality and is relatively transferable to other systems. Furthermore, when cover effects are considered, the habitat quality is more accurately represented; thus, combining the energetic profitability and the cover effects might improve the transferability of the assessment across habitats