1,021 research outputs found

    Scalable Multifunctional Ultra-thin Graphite Sponge: Free-standing, Superporous, Superhydrophobic, Oleophilic Architecture with Ferromagnetic Properties for Environmental Cleaning.

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    Water decontamination and oil/water separation are principal motives in the surge to develop novel means for sustainability. In this prospect, supplying clean water for the ecosystems is as important as the recovery of the oil spills since the supplies are scarce. Inspired to design an engineering material which not only serves this purpose, but can also be altered for other applications to preserve natural resources, a facile template-free process is suggested to fabricate a superporous, superhydrophobic ultra-thin graphite sponge. Moreover, the process is designed to be inexpensive and scalable. The fabricated sponge can be used to clean up different types of oil, organic solvents, toxic and corrosive contaminants. This versatile microstructure can retain its functionality even when pulverized. The sponge is applicable for targeted sorption and collection due to its ferromagnetic properties. We hope that such a cost-effective process can be embraced and implemented widely

    1RXS J180408.9-342058: an ultra compact X-ray binary candidate with a transient jet

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    We present a detailed NIR/optical/UV study of the transient low mass X-ray binary 1RXS J180408.9-342058 performed during its 2015 outburst, aimed at determining the nature of its companion star. We obtained three optical spectra at the 2.1 m San Pedro Martir Observatory telescope (Mexico). We performed optical and NIR photometric observations with both the REM telescope and the New Technology Telescope (NTT) in La Silla. We obtained optical and UV observations from the Swift archive. Finally, we performed optical polarimetry of the source by using the EFOSC2 instrument mounted on the NTT. The optical spectrum of the source is almost featureless since the hydrogen and He I emissions lines, typically observed in LMXBs, are not detected. Similarly, carbon and oxygen lines are neither observed. We marginally detect the He II 4686 AA emission line, suggesting the presence of helium in the accretion disc. No significant optical polarisation level was observed. The lack of hydrogen and He I emission lines in the spectrum implies that the companion is likely not a main sequence star. Driven by the tentative detection of the He II 4686 AA emission line, we suggest that the system could harbour a helium white dwarf. If this is the case, 1RXS J180408.9-342058 would be an ultra-compact X-ray binary. By combining an estimate of the mass accretion rate together with evolutionary tracks for a He white dwarf, we obtain a tentative orbital period of ~ 40 min. On the other hand, we also built the NIR-optical-UV spectral energy distribution (SED) of the source at two different epochs. One SED was gathered when the source was in the soft X-ray state, and it is consistent with the presence of a single thermal component. The second SED, obtained when the source was in the hard X-ray state, shows a thermal component together with a tail in the NIR, likely indicating the presence of a (transient) jet.Comment: 8 pages, 5 figures, 4 tables. Accepted for publication in Astronomy & Astrophysics (Section 7

    A radiating dyon solution

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    We give a non-static exact solution of the Einstein-Maxwell equations (with null fluid), which is a non-static magnetic charge generalization to the Bonnor-Vaidya solution and describes the gravitational and electromagnetic fields of a nonrotating massive radiating dyon. In addition, using the energy-momentum pseudotensors of Einstein and Landau and Lifshitz we obtain the energy, momentum, and power output of the radiating dyon and find that both prescriptions give the same result.Comment: 9 pages, LaTe

    Origin of Silicic Volcanic Rocks in Central Costa Rica: A Study of a Chemically Variable Ash-Flow Sheet in the TiribĂ­ Tuff

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    Chemical heterogeneities of pumice clasts in an ash-flow sheet can be used to determine processes that occur in the magma chamber because they represent samples of magma that were erupted at the same time. The dominant ash-flow sheet in the Tiribí Tuff contains pumice clasts that range in composition from 55.1 to 69.2 wt% SiO2. It covers about 820 km2 and has a volume of about 25 km3 dense-rock equivalent (DRE). Based on pumice clast compositions, the sheet can be divided into three distinct chemical groupings: a low-silica group (55.1–65.6 wt% SiO2), a silicic group (66.2–69.2 wt% SiO2), and a mingled group (58.6–67.7 wt% SiO2; all compositions calculated 100% anhydrous). Major and trace element modeling indicates that the low-silica magma represents a mantle melt that has undergone fractional crystallization, creating a continuous range of silica content from 55.1–65.6 wt% SiO2. Eu/Eu*, MREE, and HREE differences between the two groups are not consistent with crystal fractionation of the low-silica magma to produce the silicic magma. The low-silica group and the silicic group represent two distinct magmas, which did not evolve in the same magma chamber. We suggest that the silicic melts resulted from partial melting of relatively hot, evolved calc-alkaline rocks that were previously emplaced and ponded at the base of an over-thickened basaltic crust. The mingled group represents mingling of the two magmas shortly before eruption. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00445-001-0188-8

    Smallholder Dairy Farmers in the Peruvian Andes Fulfilling the Role of Extension Agents

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    Dairy farming in the Peruvian Andes is mostly undertaken by smallholder farmers (4-6 cows/family) and of relatively recent development. In fact, over the last 2 decades dairy farming at high altitudes (3,500‒4200 masl) has grown rapidly, replacing the camelids and sheep farming that once predominated. Dairying growth has been catalysed by subsides from state and private organizations. It promotes high input systems based on feedlot technology. Compared to sheep and camelids farming, dairying at the Andes does not have yet an inherent local/indigenous knowledge associated to it. High altitude Andean ecosystems pose many constraints for dairy farming (hypoxia and high UV radiation, high variation between day and night temperatures, short rainy season, and hence shortage of feed and water; and not less importantly, accelerated climate change (CC)). Under these conditions, not only are productivity and profitability low, but there are high negative environmental impacts and poor animal welfare. In Peru, institutionalised research and extension (R&E) services are precarious. Research tackling current issues of high-altitude livestock farming is almost inexistent, whereas extension in support of farmers is dispersed, poorly funded, of short duration (a few months), focused on transfer of technology suitable to intensive farming systems, and has a high turnover of staff. A systems approach to address the complexity of Andean livestock farming development is lacking. The initiatives from the institutions promoting farming are directed to remediate recurrent problems (e.g., cold stress) or prioritise high cost, low impact activities (e.g., genetic improvement). Here, we present the successful experience of the New Zealand Peru Dairy Support Project (NZPDSP) to promote the adoption of improved low input pastoral dairying husbandry principles, where trained smallholder farmers play a key role as agents of change

    Dairy Cattle Genetics by Environment Interaction Mismatch Contributes to Poor Mitigation and Adaptation of Grazing Systems to Climate Change Actions in the Peruvian High Andes: A Review

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    The high Andes of Peru includes fragile ecosystems. Nevertheless, it plays important ecosystem functions (e.g., biodiversity, water supply for the lowlands, CO2 sinks in soil, etc). More than 80% of the livestock population of Peru is farmed in this area, supporting the livelihood of approximately 1’400,000 poor families, who are vulnerable to climate change (CC). Climate change in the high Andes is occurring at accelerated rates, compared to lowlands regions. Prevalent factors in the high Andes, such as hypoxia, high UV radiation, climatic extremes, large variation between maximum and minimum temperatures, seasonality in rainfall (determining highly seasonal forage growth) and CC, not only increase the feed and water needs of animals, but also affect animal production, reproduction, rumen function and welfare, making them more vulnerable to CC. During the last three decades, livestock farming in the high Andes has undergone transformation. The farming of camelids and creole species has been almost replaced by smallholder dairying, which have a higher environmental footprint. Institutions promoting dairying neglect the fitness requirement for the animal genetics to perform in such environments. Recent work of the New Zealand Peru Dairy Support Project (NZPDSP; 2016‒2020) demonstrated that rapid and significant improvements in animal productivity and profitability of dairying can be achieved by promoting adoption of simple and low-cost husbandry practices. Nevertheless, further improvements are constrained by the unfitness of the current animal genetics. Here, based on a literature review and experience from the NZPDSP, we propose a search for dairy cattle genetics that contributes to mitigation and adaptation to CC, while enhancing the livelihoods of the poor

    Patient-Reported Value of a Standardized Welcome Letter for Huntington Disease Clinic

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    Communication is an essential component of patient satisfaction, which can be especially challenging in patients with neurobehavioral symptoms. As an effective form of communication, Patient Welcome Letter (PWL) should be designed in a way to cover a wide range of literacy. We designed a PWL for our Huntington Disease (HD) clinic using readability and suitability measures. Of the 80 patients that received the PWL, 47 filled out the survey. A majority of patients (\u3e90%) found the PWL clear, understandable, and well-organized. The PWL was deemed valuable overall by 91.4% of participants

    An international network to monitor the structure, composition and dynamics of Amazonian forests (RAINFOR)

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    The Amazon basin is likely to be increasingly affected by environmental changes: higher temperatures, changes in precipitation, CO2 fertilization and habitat fragmentation. To examine the important ecological and biogeochemical consequences of these changes, we are developing an international network, RAINFOR, which aims to monitor forest biomass and dynamics across Amazonia in a co-ordinated fashion in order to understand their relationship to soil and climate. The network will focus on sample plots established by independent researchers, some providing data extending back several decades. We will also conduct rapid transect studies of poorly monitored regions. Field expeditions analysed local soil and plant properties in the first phase (2001–2002). Initial results suggest that the network has the potential to reveal much information on the continental-scale relations between forest and environment. The network will also serve as a forum for discussion between researchers, with the aim of standardising sampling techniques and methodologies that will enable Amazonian forests to be monitored in a coherent manner in the coming decades
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