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  1. Consumer-mediated movement can couple food webs in distinct habitats and facilitate energy flow between them. In New England saltmarshes, mummichogs (Fundulus heteroclitus) connect the vegetated marsh and creek food webs by opportunistically foraging on the invertebrate communities of the marsh surface when access is permitted by tidal flooding and marsh-edge geomorphology. Via their movements, mummichog represent a critical food web node, as they can potentially transport energy from the marsh surface food web to creek food web and exert top-down control on the communities of the vegetated marsh surface. Here, I use gut content analysis, calorimetric analysis, and field surveysmore »to demonstrate that access to the marsh surface (afforded by marsh-edge geomorphology) impacts the trophic relay of marsh production to creek food webs. Fish populations in creeks with greater connectivity had a higher total biomass of terrestrial invertebrates in their guts. However, bomb calorimetry showed no difference in the average caloric content of mummichog individuals from creeks with different creek edge geomorphology. Access also did not impact mummichog distribution across the marsh platform and exhibited no evidence of top-down control on their invertebrate prey. Thus, mummichogs function as initial nodes in the trophic relay, unidirectionally moving energy from the vegetated marsh to the creek food web. Reduced marsh surface access via altered marsh-edge geomorphology results in a 50 % to 66 % reduction in total energy available to aquatic predators via this route. Estuarine systems are intimately connected to coastal and offshore systems via consumer mediated flows of energy; thus, disruptions to the trophic relay from the marsh surface at the tidal creek scale can have far reaching impacts on secondary productivity in multiple disparate systems and must be accounted for in considerations of impacts to future food-web function.« less
  2. Presentation by OSC Sys Admins at the ACM SIGHPC SYSPROS Symposium held in conjunction with the PEARC19 conference
  3. Abstract Context Most protected areas are managed based on objectives related to scientific ecological knowledge of species and ecosystems. However, a core principle of sustainability science is that understanding and including local ecological knowledge, perceptions of ecosystem service provision and landscape vulnerability will improve sustainability and resilience of social-ecological systems. Here, we take up these assumptions in the context of protected areas to provide insight on the effectiveness of nature protection goals, particularly in highly human-influenced landscapes. Objectives We examined how residents’ ecological knowledge systems, comprised of both local and scientific, mediated the relationship between their characteristics and a setmore »of variables that represented perceptions of ecosystem services, landscape change, human-nature relationships, and impacts. Methods We administered a face-to-face survey to local residents in the Sierra de Guadarrama protected areas, Spain. We used bi- and multi-variate analysis, including partial least squares path modeling to test our hypotheses. Results Ecological knowledge systems were highly correlated and were instrumental in predicting perceptions of water-related ecosystem services, landscape change, increasing outdoors activities, and human-nature relationships. Engagement with nature, socio-demographics, trip characteristics, and a rural–urban gradient explained a high degree of variation in ecological knowledge. Bundles of perceived ecosystem services and impacts, in relation to ecological knowledge, emerged as social representation on how residents relate to, understand, and perceive landscapes. Conclusions Our findings provide insight into the interactions between ecological knowledge systems and their role in shaping perceptions of local communities about protected areas. These results are expected to inform protected area management and landscape sustainability.« less
  4. Project update from the Open OnDemand User Group meeting held at the PEARC 19 conference
  5. Abstract Quantum chromodynamics, the theory of the strong force, describes interactions of coloured quarks and gluons and the formation of hadronic matter. Conventional hadronic matter consists of baryons and mesons made of three quarks and quark-antiquark pairs, respectively. Particles with an alternative quark content are known as exotic states. Here a study is reported of an exotic narrow state in the D 0 D 0 π + mass spectrum just below the D *+ D 0 mass threshold produced in proton-proton collisions collected with the LHCb detector at the Large Hadron Collider. The state is consistent with the ground isoscalarmore »$${{{{{{\rm{T}}}}}}}_{{{{{{\rm{c}}}}}}{{{{{\rm{c}}}}}}}^{+}$$ T c c + tetraquark with a quark content of $${{{{{\rm{c}}}}}}{{{{{\rm{c}}}}}}\overline{{{{{{\rm{u}}}}}}}\overline{{{{{{\rm{d}}}}}}}$$ c c u ¯ d ¯ and spin-parity quantum numbers J P  = 1 + . Study of the DD mass spectra disfavours interpretation of the resonance as the isovector state. The decay structure via intermediate off-shell D *+ mesons is consistent with the observed D 0 π + mass distribution. To analyse the mass of the resonance and its coupling to the D * D system, a dedicated model is developed under the assumption of an isoscalar axial-vector $${{{{{{\rm{T}}}}}}}_{{{{{{\rm{c}}}}}}{{{{{\rm{c}}}}}}}^{+}$$ T c c + state decaying to the D * D channel. Using this model, resonance parameters including the pole position, scattering length, effective range and compositeness are determined to reveal important information about the nature of the $${{{{{{\rm{T}}}}}}}_{{{{{{\rm{c}}}}}}{{{{{\rm{c}}}}}}}^{+}$$ T c c + state. In addition, an unexpected dependence of the production rate on track multiplicity is observed.« less
    Free, publicly-accessible full text available December 1, 2023
  6. This paper reports on the first phase of research on a scholarship program VTAB (Vertical Transfers’ Access to the Baccalaureate) funded by a five-year grant from the National Science Foundation (NSF) that focuses on students who transfer at the 3rd year level from 2-year schools to the engineering and engineering technology BS programs at our university [1]. The goals of the program are: (i) to expand and diversify the engineering/technology workforce of the future, (ii) to develop linkages and articulations with 2-year schools and their S-STEM programs, (iii) to recruit, retain, and graduate 78 low-income students, and place them inmore »industry or graduate schools, (iv) to generate knowledge about the program elements that can help other universities, and (v) to serve as a model for other universities to provide vertical transfer students access to the baccalaureate degree.« less
  7. Poster on using R Shiny Apps within Open OnDemand presented at the PEARC 19 conference
  8. Given the highly empirical nature of research in cloud computing, networked systems, and related fields, testbeds play an important role in the research ecosystem. In this paper, we cover one such facility, CloudLab, which supports systems research by providing raw access to programmable hardware, enabling research at large scales, and creating as hared platform for repeatable research.We present our experiences designing CloudLab and operating it for four years, serving nearly 4,000 users who have run over 79,000 experiments on 2,250 servers, switches, and other pieces of datacenter equipment. From this experience,we draw lessons organized around two themes. The first setmore »comes from analysis of data regarding the use of CloudLab:how users interact with it, what they use it for, and the implications for facility design and operation. Our second set of lessons comes from looking at the ways that algorithms used“under the hood,” such as resource allocation, have important—and sometimes unexpected—effects on user experience and behavior. These lessons can be of value to the designers and operators of IaaS facilities in general, systems testbeds in particular, and users who have a stake in understanding how these systems are built.« less
  9. Abstract Conventional, hadronic matter consists of baryons and mesons made of three quarks and a quark–antiquark pair, respectively 1,2 . Here, we report the observation of a hadronic state containing four quarks in the Large Hadron Collider beauty experiment. This so-called tetraquark contains two charm quarks, a $$\overline{{{{{u}}}}}$$ u ¯ and a $$\overline{{{{{d}}}}}$$ d ¯ quark. This exotic state has a mass of approximately 3,875 MeV and manifests as a narrow peak in the mass spectrum of D 0 D 0 π + mesons just below the D *+ D 0 mass threshold. The near-threshold mass together with the narrow widthmore »reveals the resonance nature of the state.« less
    Free, publicly-accessible full text available July 1, 2023