Total Reservoir Research Articles

Biomass assessment of microbial surface communities by means of hyperspectral remote sensing data

Dryland vegetation developed morphological and physiological strategies to cope with drought. However, as aridity increases, vascular plant coverage gets sparse and microbially-dominated surface communities (MSC), comprising cyanobacteria, algae, lichens and bryophytes together with heterotropic bacteria, archaea and fungi, gain relevance. Nevertheless, the relevance of MSC net primary productivity has only rarely been considered in ecosystem scale studies, and detailed information on their contribution to the total photosynthetic biomass reservoir is largely missing.In this study, we mapped the spatial distribution of two different MSC (biological soil crusts and quartz fields hosting hypolithic crusts) at two different sites within the South African Succulent Karoo (Soebatsfontein and Knersvlakte). Then we characterized both types of MSC in terms of chlorophyll content, and combining these data with the biocrust and quartz field maps, we estimated total biomass values of MSCs and their spatial patterns within the two different ecosystems. Our results revealed that MSC are important vegetation components of the South African Karoo biome, revealing clear differences between the two sites. At Soebatsfontein, MSC occurred as biological soil crusts (biocrusts), which covered about one third of the landscape reaching an overall biomass value of ~480gha−1 of chlorophyll a+b at the landscape scale. In the Knersvlakte, which is characterized by harsher environmental conditions (i.e. higher solar radiation and potential evapotranspiration), MSC occurred as biocrusts, but also formed hypolithic crusts growing on the lower soil-immersed parts of translucent quartz pebbles. Whereas chlorophyll concentrations of biocrusts and hypolithic crusts where insignificantly lower in the Knersvlakte, the overall MSC biomass reservoir was by far larger with ~780gha−1 of chlorophyll a+b. Thus, the complementary microbially-dominated surface communities promoted biomass formation within the environmentally harsh Knersvlakte ecosystem.

Assessment of dam effects on streams and fish assemblages of the conterminous USA

Despite the prevalence of damming as a global disturbance to river habitats, detailed reach-based assessments of the ecological effects of dams are lacking, particularly across large spatial extents. Using data from nearly 50,000 large dams, we assessed stream network fragmentation and flow alteration by large dams for streams of the conterminous USA. We developed 21 dam metrics characterizing a diversity of dam influences operating at both localized (e.g., distances-to-dams) and landscape scales (e.g., cumulative reservoir storage throughout stream networks) for every stream reach in the study region. We further evaluated how dams have affected stream fish assemblages within large ecoregions using more than 37,000 stream fish samples. Streams have been severely fragmented by large dams, with the number of stream segments increasing by 801% compared to free-flowing streams in the absence of dams and a staggering 79% of stream length is disconnected from their outlet (i.e., oceans and Great Lakes). Flow alteration metrics demonstrate a landscape-scale disturbance of dams, resulting in total upstream reservoir storage volumes exceeding estimated annual discharge volumes of many of the nation’s largest rivers. Further, we show large-scale changes in fish assemblages with dams. Species adapted to lentic habitats increase with dams across the conterminous USA, while rheophils, lithophils, and intolerant fishes decrease with dams. Overall, fragmentation and flow alteration by dams have affected fish assemblages as much or more than other anthropogenic stressors, with dam effects generally increasing with stream size. Dam-induced stream fragmentation and flow alteration are critical natural resource issues. This study emphasizes the importance of considering dams as a landscape-scale disturbance to river habitats along with the need to assess differential effects that dams may have on river habitats and the fishes they support. Together, these insights are essential for more effective conservation of stream resources and biotic communities globally.

Can research at the end of life be a useful tool to advance HIV cure?

OPINION Can research at the end of life be a useful tool to advance HIV cure? Sara Gianella a , Jeff Taylor b , Timothy R. Brown c , Andy Kaytes b , Cristian L. Achim a , David J. Moore a , Susan J. Little a , Ronald J. Ellis a and Davey M. Smith a,d AIDS 2017, 31:1–4 Keywords: end of life, eradication, HIV cure, last gift, legacy, peri-mortem research model, research Modern antiretroviral therapy (ART) has saved millions of years of life [1], but it cannot eradicate latently infected cells [2,3]. The replication-competent provirus that remains during ART represents the major barrier to curing HIV [4]. Most of this latent reservoir resides in solid tissues and not in circulating blood, and we have yet to fully define the sanctuary sites of HIV persistence [5]. Timothy Ray Brown (known by many as the ‘Berlin Patient’) may be the closest to an HIV cure after being treated with an allogeneic hematopoietic stem cell transplant from a donor who was homozygous for the CCR5D32 deletion [6]. Unfortunately, this remarkable success has not been reproduced, and robust viral replication resumes almost universally following treat- ment interruption [7–9]. Even if strategies currently in development succeed in purging HIV from circulating CD4 þ T cells, residual virus can remain in the central nervous system (CNS), gut-associated lymphoid tissue (GALT), genital tract, adipose tissue, and others [9–12]. Thus, cure efforts must tackle the eradication of HIV reservoirs in anatomic compartments and sanctuaries throughout the body. The earliest stages of HIV infection are characterized by high levels of viral replication and little immune response [13,14]. This window of uncontrolled replication allows the virus to seed reservoirs throughout the body, as early as within 2 weeks of HIV infection [15], and to persist indefinitely throughout the lifespan of HIV-infected individuals [10]. These proviral reservoirs continue to expand and diversify until viral replication is successfully suppressed with ART. Despite extensive investigations, we still do not fully understand the dynamics of the total body HIV reservoir and how sub-reservoirs in various compart- ments relate to one another. For example, it remains unclear what factors govern the size and the activity of replication-competent HIV DNA in the CNS compared to the genital tract and blood. Most studies that have explored nonblood reservoirs among persons living with HIV infection have been limited to small samples of cerebrospinal fluid (CSF), genital secretion, gut, and shallow lymph nodes [10,16]. Studies using macaque models with simian immunodeficiency viruses (SIVs) have been enlightening for reservoirs in different tissues [17–23], but while SIV shares a high degree of structural and sequence identity to HIV, studies of SIV will not suffice to test eradication strategies for humans. For example, the Merck adenovirus type 5 (Ad5) trivalent HIV-1 vaccine trial (STEP trial) did not show efficacy in preventing HIV infection or slowing disease progression [24], despite promising results in various macaques’ trials [25–27]. As the field tackles the ambitious goal of eradicating HIV from the human body, we will need to test the effectiveness of cure interventions in living persons. a University of California, San Diego, La Jolla, b Community Advisory Board (CAB) AntiViral Research Center (AVRC), c Las Vegas, Nevada, and d Veterans Affairs San Diego Healthcare System, San Diego, California, USA. Correspondence to Sara Gianella, University of California San Diego, 9500 Gilman Drive, MC 0679, La Jolla, CA 92093-0679, USA. Tel: +1 858 642 1620; fax: +1 858 552 7445; e-mail: gianella@ucsd.edu Received: 18 August 2016; revised: 23 September 2016; accepted: 27 September 2016. DOI:10.1097/QAD.0000000000001300 ISSN 0269-9370 Copyright Q 2016 Wolters Kluwer Health, Inc. All rights reserved. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.

Stability and bifurcation analysis of Japanese encephalitis model with/without effects of some control parameters

In this paper, a mathematical model on transmission of Japanese Encephalitis disease has been developed considering some control parameters and time-dependent environmental-carrying capacity. Here, the total vector population is divided into two subpopulations such as susceptible mosquito and infected mosquito. Here also, total reservoir population (i.e., the population in which the encephalitis virus grows) such as pig, horse, etc., has been considered which is divided into three subpopulations such as susceptible reservoir, infected reservoir and recovered reservoir. Total human population is also divided into three subpopulations such as susceptible human, infected human and recovered human. The dynamical behaviors of the system have been investigated. Here, the basic reproduction number associated with the system has been analyzed with respect to control parameters both theoretically and numerically. The biological feasible equilibria and their stability properties have been discussed and the existence condition of the disease has been illustrated numerically. For a certain set of parametric values, effectiveness of control parameters of our proposed model has been checked numerically. At last, Hopf bifurcations have been made numerically without considering control parameters for the case of constant environmental-carrying capacity of mosquito.

Volatiles and the tempo of flood basalt magmatism

Individual flood basalt lavas often exceed 103 km3 in volume, and many such lavas erupt during emplacement of flood basalt provinces. The large volume of individual flood basalt lavas implies correspondingly large magma reservoirs within or at the base of the crust. To erupt, some fraction of this magma must become buoyant and overpressure must be sufficient to encourage failure and dike propagation. The overpressure associated with a new injection of magma is inversely proportional to the total reservoir volume, and as a large magma body heats the surrounding rocks thermally activated creep will relax isotropic overpressure more rapidly. Here, we examine the viability of buoyancy overpressure as a trigger for continental flood basalt eruptions. We employ a new one-dimensional model that combines volatile exsolution, bubble growth and rise, assimilation, and permeable fluid escape from Moho-depth and crustal chambers. We investigate the temporal evolution of degassing and the eruptibility of magmas using the Siberian Traps flood basalts as a test case. We suggest that the volatile inventory set during mantle melting and redistributed via bubble motion controls ascent of magma into and through the crust, thereby regulating the tempo of flood basalt magmatism. Volatile-rich melts from low degrees of partial melting of the mantle are buoyant and erupt to the surface with little staging or crustal interaction. Melts with moderate volatile budgets accumulate in large, mostly molten magma chambers at the Moho or in the lower crust. These large magma bodies may remain buoyant and poised to erupt—triggered by volatile-rich recharge or external stresses—for ∼106 yr. If and when such chambers fail, enormous volumes of magma can ascend into the upper crust, staging at shallow levels and initiating substantial assimilation that contributes to pulses of large-volume flood basalt eruption. Our model further predicts that the Siberian Traps may have released 1019–1020 g of CO2 during a number of brief (∼104 yr) pulses, providing a plausible trigger for warming and ocean acidification during the end-Permian mass extinction. The assimilation of carbon-rich crustal rocks strongly enhances both flood basalt eruptibility and CO2 release, and the tempo of eruptions influences the environmental effects of CO2, SO2, and halogen degassing. The eruptive dynamics of flood basalts are thus inextricably linked with their environmental consequences.

Investigation of the Main Factors During Shale-gas Production Using Grey Relational Analysis

Shale gas is one of the primary types of unconventional reservoirs to be exploited in search for long-lasting resources. Production from shale gas reservoirs requires horizontal drilling with hydraulic fracturing to achieve the most economic production. However, plenty of parameters (e.g., fracture conductivity, fracture spacing, half-length, matrix permeability, and porosity,etc) have high uncertainty that may cause unexpected high cost. Therefore, to develop an efficient and practical method for quantifying uncertainty and optimizing shale-gas production is highly desirable. This paper focuses on analyzing the main factors during gas production, including petro-physical parameters, hydraulic fracture parameters, and work conditions on shale-gas production performances. Firstly, numerous key parameters of shale-gas production from the fourteen best-known shale gas reservoirs in the United States are selected through the correlation analysis. Secondly, a grey relational grade method is used to quantitatively estimate the potential of developing target shale gas reservoirs as well as the impact ranking of these factors. Analyses on production data of many shale-gas reservoirs indicate that the recovery efficiencies are highly correlated with the major parameters predicted by the new method. Among all main factors, the impact ranking of major factors, from more important to less important, is matrix permeability, fracture conductivity, fracture density of hydraulic fracturing, reservoir pressure, total organic content (TOC), fracture half-length, adsorbed gas, reservoir thickness, reservoir depth, and clay content. This work can provide significant insights into quantifying the evaluation of the development potential of shale gas reservoirs, the influence degree of main factors, and optimization of shale gas production.

Accretion onto Pre-Main-Sequence Stars

Accretion through circumstellar disks plays an important role in star formation and in establishing the properties of the regions in which planets form and migrate. The mechanisms by which protostellar and protoplanetary disks accrete onto low-mass stars are not clear; angular momentum transport by magnetic fields is thought to be involved, but the low-ionization conditions in major regions of protoplanetary disks lead to a variety of complex nonideal magnetohydrodynamic effects whose implications are not fully understood. Accretion in pre-main-sequence stars of masses ≲1M⊙ (and in at least some 2–3-M⊙ systems) is generally funneled by the stellar magnetic field, which disrupts the disk at scales typically of order a few stellar radii. Matter moving at near free-fall velocities shocks at the stellar surface; the resulting accretion luminosities from the dissipation of kinetic energy indicate that mass addition during the T Tauri phase over the typical disk lifetime ∼3 Myr is modest in terms of stellar evolution, but is comparable to total disk reservoirs as estimated from millimeter-wave dust emission (∼10−2 M⊙). Pre-main-sequence accretion is not steady, encompassing timescales ranging from approximately hours to a century, with longer-timescale variations tending to be the largest. Accretion during the protostellar phase—while the protostellar envelope is still falling onto the disk—is much less well understood, mostly because the properties of the central obscured protostar are difficult to estimate. Kinematic measurements of protostellar masses with new interfometric facilities should improve estimates of accretion rates during the earliest phases of star formation.

Effect of sporadic destratification, seasonal overturn, and artificial mixing on CH<sub>4</sub> emissions from a subtropical hydroelectric reservoir

Abstract. Inland waters in general and freshwater reservoirs specifically are recognized as a source of CH4 into the atmosphere. Although the diffusion at the air–water interface is the most studied pathway, its spatial and temporal variations are poorly documented. We measured temperature and O2 and CH4 concentrations every 2 weeks for 3.5 years at nine stations in a subtropical monomictic reservoir which was flooded in 2008 (Nam Theun 2 Reservoir, Lao PDR). Based on these results, we quantified CH4 storage in the water column and diffusive fluxes from June 2009 to December 2012. We compared diffusive emissions with ebullition from Deshmukh et al. (2014) and aerobic methane oxidation and downstream emissions from Deshmukh et al. (2016). In this monomictic reservoir, the seasonal variations of CH4 concentration and storage were highly dependent on the thermal stratification. Hypolimnic CH4 concentration and CH4 storage reached their maximum in the warm dry season (WD) when the reservoir was stratified. Concentration and storage decreased during the warm wet (WW) season and reached its minimum after the reservoir overturned in the cool dry (CD) season. The sharp decreases in CH4 storage were concomitant with extreme diffusive fluxes (up to 200 mmol m−2 d−1). These sporadic emissions occurred mostly in the inflow region in the WW season and during overturn in the CD season in the area of the reservoir that has the highest CH4 storage. Although they corresponded to less than 10 % of the observations, these extreme CH4 emissions (> 5 mmol m−2 d−1) contributed up to 50 % of total annual emissions by diffusion. During the transition between the WD and WW seasons, a new emission hotspot was identified upstream of the water intake where diffusive fluxes peaked at 600 mmol m−2 d−1 in 2010 down to 200 mmol m−2 d−1 in 2012. The hotspot was attributed to the mixing induced by the water intakes (artificial mixing). Emissions from this area contributed 15–25 % to total annual emissions, although they occur in a surface area representative of less than 1 % of the total reservoir surface. We highly recommend measurements of diffusive fluxes around water intakes in order to evaluate whether such results can be generalized.

The impact of sedimentary coatings on the diagenetic Nd flux

Because ocean circulation impacts global heat transport, understanding the relationship between deep ocean circulation and climate is important for predicting the ocean's role in climate change. A common approach to reconstruct ocean circulation patterns employs the neodymium isotope compositions of authigenic phases recovered from marine sediments. In this approach, mild chemical extractions of these phases is thought to yield information regarding the εNd of the bottom waters that are in contact with the underlying sediment package. However, recent pore fluid studies present evidence for neodymium cycling within the upper portions of the marine sediment package that drives a significant benthic flux of neodymium to the ocean. This internal sedimentary cycling has the potential to obfuscate any relationship between the neodymium signature recovered from the authigenic coating and the overlying neodymium signature of the seawater. For this manuscript, we present sedimentary leach results from three sites on the Oregon margin in the northeast Pacific Ocean. Our goal is to examine the potential mechanisms controlling the exchange of Nd between the sedimentary package and the overlying water column, as well as the relationship between the εNd composition of authigenic sedimentary coatings and that of the pore fluid. In our comparison of the neodymium concentrations and isotope compositions from the total sediment, sediment leachates, and pore fluid we find that the leachable components account for about half of the total solid-phase Nd, therefore representing a significant reservoir of reactive Nd within the sediment package. Based on these and other data, we propose that sediment diagenesis determines the εNd of the pore fluid, which in turn controls the εNd of the bottom water. Consistent with this notion, despite having 1 to 2 orders of magnitude greater Nd concentration than the bottom water, the pore fluid is still <0.001% of the total Nd reservoir in the upper sediment column. Therefore, the pore fluid reservoir is too small to maintain a unique signature, and instead must be controlled by the larger reservoir of Nd in the reactive coatings. In addition, to achieve mass balance, we find it necessary to invoke a cryptic radiogenic (εNd of +10) trace mineral source of neodymium within the upper sediment column at our sites. When present, this cryptic trace metal results in more radiogenic pore fluid.

Logging identification and characteristic analysis of the lacustrine organic-rich shale lithofacies: A case study from the Es3L shale in the Jiyang Depression, Bohai Bay Basin, Eastern China

The Es3L (lower sub-member of the third member of the Eocene Shahejie Formation) shale of Jiyang depression was a set of relatively thick and widely deposited lacustrine sediments with high organic richness and medium thermal maturation (0.7%≤Ro≤1.1%), which rapidly emerges an important and target shale-oil play in Eastern China. An important component for shale-oil reservoir evaluation is lithofacies that affect hydraulic fracture stimulation and constrain significant organic-matter and oil concentration. Based on core and thin section observation, X-ray diffraction and comparative analysis of well logging data, we can define the types of shale lithofacies in the Es3L and determine log response characteristics of each lithofacies to show effective methods for identifying or predicting the lithofacies from conventional well logs. Organic richness, porosity and permeability measurements and the analysis of scanning electron microscope (SEM) images were used to study the impact of lithofacies on total organic carbon (TOC), reservoirs properties and oil content. The Es3L shale is rich in carbonate minerals (most >50%). According to the mineral composition, sedimentary structure and genesis, the lithofacies can be divided into 5 types and 2 sub-categories: marl (including massive and bedded), calcareous shale (including massive and bedded), laminated bindstone, massive silty mudstone and argillaceous shale. By the analysis of log response characteristics of lithofacies from 17 wells, 8 sensitive logging curves (e.g., density (DEN), acoustic times (AC) and resistance (Rt)) were optimized to construct logging recognition models and conduct cross plots to qualitatively identify lithofacies. On this basis, using the Fisher Discrimination Analysis and Naïve Bayes Classification Function, 5 types of shale lithofacies were quantitatively identified and predicted. Combined with the identification of shale beddings from Formation MicroScanner Imaging (FMI), the 7 sub-categories of shale lithofacies can be further recognized. The statistics of lithofacies indicate that bedded marl and calcareous shale are the dominant lithofacies in the Es3L. TOC content has the wide variation between different lithofacies (0.06–12%). The argillaceous shale has the high TOC content, followed by calcareous shale and bindstone. TOC is positively correlated to clay and pyrite content, and negatively correlated to quartz. The measurements of reservoir properties indicate that bindstone and calcareous shale have high porosity (>7.0%) and good permeability. A general positive relationship between porosity and TOC, quartz or carbonate minerals indicates that organic matter (OM), recrystallized intercrystal and interparticle pores in BSE images can improve the porosity. Additionally, the oil accumulation index (OAI) of bindstone, calcareous shale and argillaceous shale is high. Considered reservoir properties and fracability, the laminated bindstone and bedded calcareous shale in the medium-low section of Es3L are the most advantageous lithofacies for shale-oil exploration and exploitation in this area.

Effects of disturbed landforms on the soil water retention function during urbanization process in the Three Gorges Reservoir Region, China

Decreases in the water retention function of various artificial disturbed landform units (DLUs) caused by urbanization activities, compared to original landform units (OLUs), are the main factor that causes urban water and soil loss and the aggravation of urban floods under certain rainfall conditions and specially designed drainage network capabilities. Field investigations, laboratorial analyses of soil physical properties and analytic hierarchy process (AHP) composite methods were performed to comprehensively analyse the effects of various DLUs on the water retention function of OLUs. The results indicated as the following: (і) The >5mm particle content (>54%) for various DLUs was higher than that for OLUs (lower than 3%); the natural repose angles of soil-rock mixtures (32–37°) and soil bulk density (1.41–1.74g/cm3) in the DLUs were all higher than those in the OLUs (30–31°, 1.18–1.14g/cm3); and the uniformity coefficients and curvature coefficients were 10.00–80.00 and 3.24–5.70 in the DLUs and 6.00–75.00 and 0.17–2.50 in the OLUs, respectively. (ii) The soil steady state infiltration rate in the DLUs decreased from disturbed soil accumulation with 2months (DSA2m, 15.00mm/min) to disturbed soil accumulation with 2years (DSA2a, 5.63mm/min), disturbed soil accumulation with 4years (DSA4a, 3.82mm/min), the slope greening belt (SGB, 1.24mm/min), and construction roads (CR, 0.51mm/min). The conversion from forests to DSA2m had the greatest impact on the soil infiltration capacity and soil storage capacity, while the conversion to CR had the lowest impact. (iii) The total reservoir storage in the DLUs' soil was ordered as follows: DSA4a>SGB>DSA2a>DSA2m>CR. The conversion process from grass to CR exerted the greatest impact on storing water and regulating the overland flow. (iv) The water retention functions in the DLUs were all weaker than those in the OLUs: DSA2m was the weakest (0.287), while paddy fields were the strongest (0.668). Thus, the occupied areas of urban water surfaces (e.g., lakes, rivers and ponds), forests and grassland and their spatial distribution during urbanization must be carefully considered. These results could help to understand the ecological service functions of urban soil and water conservation, provide relevant knowledge to landscape rehabilitation, alleviate urban floods during urban development and recover the functions of soil and water conservation ecological services in project areas during the urbanization construction process.

Soil water reservoir properties and influencing factors of typical newly-established green belts of Shanghai Chenshan Botanical Garden, China.

The effects of different vegetation types, compaction ways and soil basic physico-chemical properties on soil water reservoir in the typical newly-established green belts of Shanghai Chenshan Botanical Garden were studied. The results showed that the total reservoir capacity, detention capacity and effective storage for the Botanical Garden were lower than those of natural forests. However, the dead storage was very high accounting for 60.6% of the total reservoir capacity, resulting in reduced flood storage and drainage capacity for the greens. The total reservoir capacity and detention capacity of different vegetation types were in order of brush land> tree land> grassland> bamboo land> bare land. The effective storages of the brush land and the tree land were relatively high, whereas those of the bare land and the bamboo land were lower. The ratios of the dead storage over the total re-servoir capacity in the bare land and the bamboo land were relatively high with the values 65.5% and 67.6%, respectively. The total reservoir capacity, detention capacity and effective storage of the brush land were significantly different from those of the bare land. The vegetation significantly improved the water storage and retention capacity for the soil, while the compaction by large machinery and man-caused trampling reduced the total reservoir capacity, detention capacity and effective storage of soils. The water reservoir properties were influenced by soil bulk density, saturated hydraulic conductivity, capillary porosity, non-capillary porosity, total porosity, clay and organic matter contents. Therefore, improving the soil physico-chemical properties might increase the soil reservoir capacity of the urban green belt effectively.

Upscaling and simulation of composite gas reservoirs with thin-interbedded shale and tight sandstone

This paper focused on the reservoir simulation of composite gas reservoirs with interbedded shale and tight sandstone. The mentioned simulation confronts a series of problems such as computational inefficiency and serious convergence issues due to the numerous extremely thin layers in such reservoirs. Although various upscaling methods can solve these problems, they only reflect the average flow. Thus, we present an improved upscaling and simulation method. Firstly, we regard two types of rocks as dual porous media to replace single porous media used in traditional methods. Secondly, hydraulic fracturing is considered by modeling the primary fractures as discrete fractures and idealizing the secondary fractures as continuous. As such, the total reservoir is classified into three regions: (1) the triple porosity region, which contains pores of the two rocks and the secondary fractures; (2) the dual porosity region, which contains pores of the two rocks; and (3) the discrete fracture region, which indicates the primary fracture. Thirdly, the formulas for the transfer term between any two types of porosities are derived. The derived formulas are similar to but different from the existing formula. Furthermore, the upscaling methods for porosity and permeability are presented. Notably, our method can avert the challenge of upscaling the parametric curves of different rocks, e.g., capillary pressure, relative permeability, and gas adsorption–desorption. Finally, we use a real gas reservoir as an example to assess three schemes, i.e., fine grid-cells with singular porosity (FGSP), coarse grid-cells with singular porosity (CGSP), and coarse grid-cells with dual porosity (CGDP). Consequently, the CGDP results are much closer to those of FGSP, with just 1/25 grid cells and shorter computing time, unlike CGSP, which is not capable of reflecting the flow differences between the shale and siltstone. Therefore, we conclude that our method can not only improve the computing efficiency but can also guarantee accuracy.

In situ imaging reveals the biomass of giant protists in the global ocean.

Planktonic organisms play crucial roles in oceanic food webs and global biogeochemical cycles. Most of our knowledge about the ecological impact of large zooplankton stems from research on abundant and robust crustaceans, and in particular copepods. A number of the other organisms that comprise planktonic communities are fragile, and therefore hard to sample and quantify, meaning that their abundances and effects on oceanic ecosystems are poorly understood. Here, using data from a worldwide in situ imaging survey of plankton larger than 600 μm, we show that a substantial part of the biomass of this size fraction consists of giant protists belonging to the Rhizaria, a super-group of mostly fragile unicellular marine organisms that includes the taxa Phaeodaria and Radiolaria (for example, orders Collodaria and Acantharia). Globally, we estimate that rhizarians in the top 200 m of world oceans represent a standing stock of 0.089 Pg carbon, equivalent to 5.2% of the total oceanic biota carbon reservoir. In the vast oligotrophic intertropical open oceans, rhizarian biomass is estimated to be equivalent to that of all other mesozooplankton (plankton in the size range 0.2-20 mm). The photosymbiotic association of many rhizarians with microalgae may be an important factor in explaining their distribution. The previously overlooked importance of these giant protists across the widest ecosystem on the planet changes our understanding of marine planktonic ecosystems.

The rise of Rhizaria

Large amoeba-like organisms known as Rhizaria have often been overlooked in studies of ocean biology and biogeochemistry. Underwater imaging and ecological network analyses are revealing their roles. See Article p.465 & Letter p.504 Ocean ecosystems are inhabited by planktonic organisms spanning a wide size range, with large zooplankton feeding on smaller species and thereby contributing to the marine food web and carbon cycling. However, our understanding of the role and contribution of fragile and large zooplankton to the marine ecosystem is limited. Using data collected by an in situ imaging system during the Tara Oceans global survey, Tristan Biard et al. quantified the respective contributions of Rhizaria (a broad phylogenetic group of marine protists) and other zooplankton larger than 600 μm, finding that they represent a much larger biomass than previously appreciated, contributing up to 5.2% of the total oceanic biota carbon reservoir. These findings highlight the important contribution of Rhizaria to plankton biomass, primary productivity and other biogeochemical processes in the oceans.

Sandstone injectivity and salt stability of cellulose nanocrystals (CNC) dispersions—Premises for use of CNC in enhanced oil recovery

Reservoir production is frequently supported by using flooding fluids, often seawater. The efficiency is affected by various factors, such as the wettability of the reservoir rock and the mobility ratio between reservoir oil and injected fluid phase. These factors again influence sweep efficiency, which is the fraction of the total reservoir oil volume in contact with injected fluid during oil recovery. Addition of nanoparticles can affect the sweep efficiency on a macroscopic level by increasing the volume of petroleum in contact with the flooding fluid. Presented here are core-flooding studies performed using cellulose nanocrystals (CNC) of different concentrations in low-saline water. The studies were performed to investigate the injectivity of CNC into a high-permeable sandstone core, and to observe the effects addition of electrolytes had on the rheological properties of a low concentration dispersion of CNC. Zeta- potential and shear viscosity of dilute dispersions containing CNC was investigated under increasing electrolyte concentration. The flooding experiments show that the CNC has good injectivity in sandstone for all concentrations used, and the viscosity measurements performed on the effluent prove that the particles are able to travel through the core. Being sufficiently small for injection into sandstone and showing good colloidal stability at low salinities, CNC particles have the premises necessary to function properly as a flooding additive for enhanced oil recovery (EOR) in sandstone reservoirs.

DIFFUSE CORONAE IN COSMOLOGICAL SIMULATIONS OF MILKY WAY-SIZED GALAXIES

ABSTRACT We investigate the properties of halo gas using three cosmological “zoom-in” simulations of realistic Milky Way-galaxy analogs with varying sub-grid physics. In all three cases, the mass of hot (T &gt; 106 K) halo gas is ∼1% of the host's virial mass. The X-ray luminosity of two of the runs is consistent with observations of the Milky Way, while the third simulation is X-ray bright and resembles more closely a very massive, star-forming spiral. Hot halos extend to 140 kpc from the galactic center and are surrounded by a bubble of warm-hot ( T = 10 5 &minus; 10 6 ?> K) gas that extends to the virial radius. Simulated halos agree well outside 20–30 kpc with the β-model of Miller &amp; Bregman based on O vii absorption and O viii emission measurements. Warm-hot and hot gas contribute up to 80% of the total gas reservoir, and contain nearly the same amount of baryons as the stellar component. The mass of warm-hot and hot components falls into the range estimated for L &ast; ?> galaxies. With key observational constraints on the density of the Milky Way corona being satisfied, we show that concealing of the ubiquitous warm-hot baryons, along with the ejection of just 20%–30% of the diffuse gas out of the potential wells by supernova-driven outflows, can solve the “missing baryon problem.” The recovered baryon fraction within 3 virial radii is 90% of the universal value. With a characteristic density of ∼10−4 cm−3 at 50–80 kpc, diffuse coronae meet the requirement for fast and complete ram-pressure stripping of the gas reservoirs in dwarf galaxy satellites.

Identifying indicators and quantifying large-scale effects of dams on fishes

Although localized effects of individual dams on stream fish assemblages have been relatively well-studied, less is known about the effects of multiple dams within a stream network on fishes and the patterns that emerge when the combined effects of individual and multiple dams are viewed across entire river basins, ecoregions, and states. This study evaluated multiple stream network fragmentation metrics representing localized (e.g., distance-to-dams) and cumulative (e.g., total upstream reservoir storage) dam influences on streams in Michigan, Wisconsin, and Minnesota, developing an approach for identifying suitable fish indicators of dam effects. We used change point and correlation analyses to determine associations of stream fish catch per unit effort and various stream network fragmentation metrics with data from more than 2000 fish survey sites stratified by stream size, thermal regime, and ecoregion. Of the identified indicator species, predominantly warmwater, large river, and/or lentic species were positively associated with stream network fragmentation, whereas cold and coolwater lotic species were negatively associated with fragmentation. These results suggest a combination of downstream thermal effects and upstream influences from impoundments generated by dams. Variance partitioning analyses based on identified indicator species revealed greater upstream-dominated dam influences in headwaters than mid-sized streams, and a greater relative influence of dams vs. other non-dam anthropogenic influences in cold streams than warm streams. Overall, a combination of localized and cumulative fragmentation metrics, as well as upstream and downstream-oriented measures, were influential in indicator species responses, emphasizing the importance of selecting a diversity of fragmentation metrics when assessing effects of dams on stream fishes. Understanding multiple dam influences on stream fishes, including localized effects from individual dams and cumulative effects from all dams within a river basin, would provide useful information for a variety of management activities, including dam operation and dam removal prioritization. Dams significantly affect conservation and management options for stream fishes, with identification of multi-scale dam influences on fishes being critical to restoration and maintenance of aquatic biodiversity throughout the world.

Cyclic ultracapacitor for fast-charging and scalable energy storage system

ESSs (Energy storage systems) for large-scale grid systems and next generation secondary battery systems require an ideal device that satisfies diverse properties such as a high energy density, high power density, low cost, and safe and reliable performance. In this study, we present a CUCap (cyclic ultracapacitor), which is comprised of two reservoirs and one flat flow capacitor cell with a cyclic continuous flow mode and independently tunable power rating and energy capacity. CUCap provides fast-charging and high capacity technology with a simple and practical design for high density and large-scale energy storage systems. The best performance appeared in slurry ratio (electrode to electrolyte) 1 to 7 with the total reservoir volume of 150 mL and the flow rate 300 ml/min, resulting in volumetric energy density, specific capacitance, and discharge time of 7.7 Wh L−1, 14.2 F ml−1, 100 min, respectively. Moreover, the slurry electrode of the CUCap cell had a maximum current density around 260 mA cm−2 which could possibly result in a fast-charging CUCap system.

Effect of urbanisation on the water retention function in the Three Gorges Reservoir Area, China

Urbanisation activities can greatly alter original landform unit shapes and reduce their water retention function, which is the major reason for serious artificial water and soil losses and widespread urban waterlogging. Taking original landform units (OLU) as a control, this work aimed to reveal the extent to which disturbed landform units (DLU) reduce the water retention function in a special building construction area. Field investigations and physical and chemical laboratory analyses were performed to analyse soil physical characteristics including the soil porosity, soil usable storage and soil stable infiltration rate. The coordinate composite method was used to evaluate the effects of urbanisation on the water retention function of the original landform during the urbanisation construction process. The soil bulk densities in the various DLU were greater than in the OLU, showing the following order: construction road (CR)>1a slope greening belt (SGB)>1a disturbed soil accumulation (DSA1)>2a disturbed soil accumulation (DSA2)>3a disturbed soil accumulation (DSA3). The soil total reservoir storage and usable storage in the different DLU were lower than in the OLU, with usable storage showing the order DSA3>DSA2>DSA1>SGB>CR, which presented decreases of 12.3%, 16.8%, 22.7%, 28.2% and 33.3%, respectively, compared with sloping land. The soil stable infiltration rate presented the order DSA3 (2.89mm/min)>SGB (2.65mm/min)>DSA2 (1.89mm/min)>DSA1 (1.64mm/min)>CR (0.45mm/min), while the soil initial infiltration showed the order DSA1>DSA3>SGB>DSA2>CR. The overall water retention function of the different landform units varied in the following order: native forest land>fruit forest land>Abandoned land>sloping land>DSA3>SGB>DSA2>CR>DSA1, with DSA1 causing the greatest harm to the water retention function of the OLU. In order to avoid causing serious soil and water losses and urban waterlogging, building construction projects should attempt to avoid strongly disturbing, occupying and destroying natural rainfall-flood regulation systems, especially for native forest land. Since soil characteristics are crucial for vegetation, these results could provide relevant knowledge to landscape rehabilitation and recovering the function of soil and water conservation ecological services in project areas during the urbanisation construction process.