527 research outputs found

    On the density matrix for the kink ground state of higher spin XXZ chain

    Full text link
    The exact expression for the density matrix of the kink ground state of higher spin XXZ chain is obtained

    Effect of CO2 enrichment on bacterial metabolism in an Arctic fjord

    Get PDF
    he anthropogenic increase of carbon dioxide (CO2) alters the seawater carbonate chemistry, with a decline of pH and an increase in the partial pressure of CO2 (pCO2). Although bacteria play a major role in carbon cycling, little is known about the impact of rising pCO2 on bacterial carbon metabolism, especially for natural bacterial communities. In this study, we investigated the effect of rising pCO2 on bacterial production (BP), bacterial respiration (BR) and bacterial carbon metabolism during a mesocosm experiment performed in Kongsfjorden (Svalbard) in 2010. Nine mesocosms with pCO2 levels ranging from ca. 180 to 1400 μatm were deployed in the fjord and monitored for 30 days. Generally BP gradually decreased in all mesocosms in an initial phase, showed a large (3.6-fold average) but temporary increase on day 10, and increased slightly after inorganic nutrient addition. Over the wide range of pCO2 investigated, the patterns in BP and growth rate of bulk and free-living communities were generally similar over time. However, BP of the bulk community significantly decreased with increasing pCO2 after nutrient addition (day 14). In addition, increasing pCO2 enhanced the leucine to thymidine (Leu : TdR) ratio at the end of experiment, suggesting that pCO2 may alter the growth balance of bacteria. Stepwise multiple regression analysis suggests that multiple factors, including pCO2, explained the changes of BP, growth rate and Leu : TdR ratio at the end of the experiment. In contrast to BP, no clear trend and effect of changes of pCO2 was observed for BR, bacterial carbon demand and bacterial growth efficiency. Overall, the results suggest that changes in pCO2 potentially influence bacterial production, growth rate and growth balance rather than the conversion of dissolved organic matter into CO2

    Production of individual marine organic aggregates using paramagnetic microspheres : a new tool for examining microbial associations with aggregates

    Get PDF
    We describe a new method to produce marine aggregates from natural organic material based on the sticking properties of transparent exopolymeric particles. Seawater samples were prescreened and ultrafiltered to concentrate the 30 kDa to 10 mu m size fraction. First, we produced small magnetizable aggregates by combining glass microfibers and paramagnetic 1-mu m beads with the organic matter present in the concentrated solution. The second step involved clustering the small aggregates into a single macro-aggregate, using a small ring-shaped magnet as an aggregation nucleus. Viral and bacterial densities, determined after dissolution of the newly formed aggregates with methanol, averaged 13.8 x 10(6) +/- 3.6 x 10(6) vir. agg.(-1) and 4.1 x 10(6) +/- 1.1 x10(6) bact. agg.(-1). Bacterial respiration and production measurements of single aggregates averaged 8.47 +/- 1.72 nmol O-2 agg.(-1) h(-1) and 1.54 +/- 0.45 ng C agg.(-1) h(-1), respectively. Particulate organic carbon and nitrogen content of the newly formed macro-aggregates averaged 31.92 +/- 2.67 mu g C agg.(-1) and 3.44 +/- 0.43 mu g N agg.(-1), respectively. This approach allows the concentration and isolation of the organic matter precursors that compose natural aggregates and provides a simple protocol for recombining those precursors into single newly formed macro-aggregates, which can then be easily manipulated for further investigation. This method is a new tool for investigations into the interactions between microorganisms and marine aggregates and their implications at the ecosystem level, but also into the interactions between aggregates and dissolved organic or inorganic substances

    Case Studies of Energy Information Systems and Related Technology: Operational Practices, Costs, and Benefits

    Get PDF
    Energy Information Systems (EIS), which can monitor and analyze building energy consumption and related data throughout the Internet, have been increasing in use over the last decade. Though EIS developers describe the capabilities, costs, and benefits of EIS, many of these descriptions are idealized and often insufficient for potential users to evaluate cost, benefit and operational usefulness. LBNL has conducted a series of case studies of existing EIS and related technology installations. This study explored the following questions: 1) How is the EIS used in day-to-day operation? 2) What are the costs and benefits of an EIS? 3) Where do the energy savings come from? This paper reviews the process of these technologies from installation through energy management practice. The study is based on interviews with operators and energy managers who use EIS. Analysis of energy data trended by EIS and utility bills was also conducted to measure the benefit. This paper explores common uses and findings to identify energy savings attributable to EIS, and discusses nonenergy benefits as well. This paper also addresses technologies related to EIS that have been demonstrated and evaluated by LBNL

    On the problem of calculation of correlation functions in the six-vertex model with domain wall boundary conditions

    Full text link
    The problem of calculation of correlation functions in the six-vertex model with domain wall boundary conditions is addressed by considering a particular nonlocal correlation function, called row configuration probability. This correlation function can be used as building block for computing various (both local and nonlocal) correlation functions in the model. The row configuration probability is calculated using the quantum inverse scattering method; the final result is given in terms of a multiple integral. The connection with the emptiness formation probability, another nonlocal correlation function which was computed elsewhere using similar methods, is also discussed.Comment: 15 pages, 2 figure

    Introduction to Commercial Building Control Strategies and Techniques for Demand Response -- Appendices

    Get PDF
    There are 3 appendices listed: (A) DR strategies for HVAC systems; (B) Summary of DR strategies; and (C) Case study of advanced demand response
    corecore