569 research outputs found
A review of the genus Coccoglypta Pilsbry, 1895 (Gastropoda: Pulmonata: Camaenidae)
FIG. 6. — Potential members of the genus Coccoglypta Pilsbry, 1895: A-D, syntype of Coccoglypta arbusticola (Deshayes, 1870) n. comb. (MNHN-IM-2000-34192); E-H, "Bradybaena" chrysomphala (Möllendorff, 1899), SMF 9159 (lectotype); I-L, Coccoglypta cf. leprosula n. comb. (Heude, 1885) from the Guanwushan Forest Farm. Scale bar: 30 mm.Published as part of Páll-Gergely, Barna, Hunyadi, András, Chen, Zhe-Yu & Lyu, Zhi-Tong, 2019, A review of the genus Coccoglypta Pilsbry, 1895 (Gastropoda: Pulmonata: Camaenidae), pp. 595-608 in Zoosystema 41 (29) on page 603, DOI: 10.5252/zoosystema2019v41a29, http://zenodo.org/record/372611
Efficiency of electrochemical chloride removal from concrete at different environmental temperatures
Electrochemical chloride removal (ECR) is an effective and curative method to treat existed reinforced concrete structures about to suffer or already suffering from chloride attack, however, its application is still limited due to its side effect and efficiency, including the velocity and maximum capacity of chloride removal. This paper presents a temperature related numerical transport model to study the effect of temperature on efficiency of electrochemical chloride removal from concrete. Based on Fick’s law and Nernst-Planck equation with Gauss’ Law, temperature effect, chloride binding, multi-species coupling, electrochemical reactions were taken into account in this model. Temperature effect was considered on diffusion coefficient, chloride binding, ions migration capacity as well as electrolyte concentration. The model was validated by the comparison between the calculated results and experimental data. The results indicate that temperature dose have a considerable influence on electrochemical chloride removal and controlling temperature during treatment is a practical method to improve the electrochemical chloride removal when applied current density is not amplified
Negative longitudinal magnetoresistance in GaAs quantum wells
Negative longitudinal magnetoresistances (NLMRs) have been recently observed
in a variety of topological materials and often considered to be associated
with Weyl fermions that have a defined chirality. Here we report NLMRs in
non-Weyl GaAs quantum wells. In the absence of a magnetic field the quantum
wells show a transition from semiconducting-like to metallic behaviour with
decreasing temperature. We observed pronounced NLMRs up to 9 Tesla at
temperatures above the transition and weak NLMRs in low magnetic fields at
temperatures close to the transition and below 5 K. The observed NLMRs show
various types of magnetic field behaviour resembling those reported in
topological materials. We attribute them to microscopic disorder and use a
phenomenological three-resistor model to account for their various features.
Our results showcase a new contribution of microscopic disorder in the
occurrence of novel phenomena. They may stimulate further work on tuning
electronic properties via disorder/defect nano-engineering
A Search for Extraterrestrial Technosignatures in Archival FAST Survey Data Using a New Procedure
The "search for extraterrestrial intelligence" (SETI) commensal surveys aim
to scan the sky to find possible technosignatures from the extraterrestrial
intelligence (ETI). The mitigation of radio frequency interference (RFI) is an
important step, especially for the most sensitive Five-hundred-meter Aperture
Spherical radio Telescope (FAST), which can detect more weak RFI. In this
paper, we propose several new techniques for RFI mitigation, and use our
procedure to search for ETI signals from the archival data of FAST's first SETI
commensal survey. We detect the persistent narrowband RFI by setting a
threshold of the signals' sky separation, and detect the drifting RFI (and
potentially other types of RFI) using the Hough transform. We also use the
clustering algorithms to remove more RFI and select candidates. The results of
our procedure are compared to the earlier work on the same FAST data. We find
that our methods, though relatively simpler in computation, remove more RFI
(99.9912% compared to 99.9063% in the earlier work), but preserve the simulated
ETI signals except those (5.1%) severely affected by the RFI. We also report
more interesting candidate signals, about a dozen of which are new candidates
that are not previously reported. In addition, we find that the proposed Hough
transform method, with suitable parameters, also has the potential to remove
the broadband RFI. We conclude that our methods can effectively remove the vast
majority of the RFI while preserving and finding the candidate signals that we
are interested in.Comment: 14 pages, 10 figures. AJ accepte
Gobi agriculture: an innovative farming system that increases energy and water use efficiencies. A review
International audienceAbstractIn populated regions/countries with fast economic development, such as Africa, China, and India, arable land is rapidly shrinking due to urban construction and other industrial uses for the land. This creates unprecedented challenges to produce enough food to satisfy the increased food demands. Can the millions of desert-like, non-arable hectares be developed for food production? Can the abundantly available solar energy be used for crop production in controlled environments, such as solar-based greenhouses? Here, we review an innovative cultivation system, namely “Gobi agriculture.” We find that the innovative Gobi agriculture system has six unique characteristics: (i) it uses desert-like land resources with solar energy as the only energy source to produce fresh fruit and vegetables year-round, unlike conventional greenhouse production where the energy need is satisfied via burning fossil fuels or electrical consumption; (ii) clusters of individual cultivation units are made using locally available materials such as clay soil for the north walls of the facilities; (iii) land productivity (fresh produce per unit land per year) is 10–27 times higher and crop water use efficiency 20–35 times greater than traditional open-field, irrigated cultivation systems; (iv) crop nutrients are provided mainly via locally-made organic substrates, which reduce synthetic inorganic fertilizer use in crop production; (v) products have a lower environmental footprint than open-field cultivation due to solar energy as the only energy source and high crop yields per unit of input; and (vi) it creates rural employment, which improves the stability of rural communities. While this system has been described as a “Gobi-land miracle” for socioeconomic development, many challenges need to be addressed, such as water constraints, product safety, and ecological implications. We suggest that relevant policies are developed to ensure that the system boosts food production and enhances rural socioeconomics while protecting the fragile ecological environment
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