218 research outputs found
Performance analysis of two typical greenhouse lettuce production systems: Commercial hydroponic production and traditional soil cultivation
Introduction: Due to the shortage of land and water resource, optimization of systems for production in commercial greenhouses is essential for sustainable vegetable supply. The performance of lettuce productivity and the economic benefit in greenhouses using a soil-based system (SBS) and a hydroponic production system (HPS) were compared in this study. Methods: Experiments were conducted in two identical greenhouses over two growth cycles (G1 and G2). Three treatments of irrigation volumes (S1, S2, and S3) were evaluated for SBS while three treatments of nutrient solution concentration (H1, H2, and H3) were evaluated for HPS; the optimal levels from each system were then compared. Results and discussion: HPS was more sensitive to the effects of environmental temperature than SBS because of higher soil buffer capacity. Compared with SBS, higher yield (more than 134%) and higher water productivity (more than 50%) were observed in HPS. We detected significant increases in ascorbic acid by 28.31% and 16.67% and in soluble sugar by 57.84% and 32.23% during G1 and G2, respectively, compared with SBS. However, nitrate accumulated in HPS-grown lettuce. When the nutrient solution was replaced with fresh water 3 days before harvest, the excess nitrate content of harvested lettuce in HPS was removed. The initial investment and total operating cost in HPS were 21.76 times and 47.09% higher than those in SBS, respectively. Consideration of agronomic, quality, and economic indicators showed an overall optimal performance of the H2 treatment. These findings indicated that, in spite of its higher initial investment and requirement of advanced technology and management, HPS was more profitable than SBS for commercial lettuce production
Measurement of the vertical atmospheric density profile from the X-ray Earth occultation of the Crab Nebula with Insight-HXMT
In this paper, the X-ray Earth occultation (XEO) of the Crab Nebula is
investigated by using the Hard X-ray Modulation Telescope (Insight-HXMT). The
pointing observation data on the 30th September, 2018 recorded by the Low
Energy X-ray telescope (LE) of Insight-HXMT are selected and analyzed. The
extinction lightcurves and spectra during the X-ray Earth occultation process
are extracted. A forward model for the XEO lightcurve is established and the
theoretical observational signal for lightcurve is predicted. The atmospheric
density model is built with a scale factor to the commonly used MSIS density
profile within a certain altitude range. A Bayesian data analysis method is
developed for the XEO lightcurve modeling and the atmospheric density
retrieval. The posterior probability distribution of the model parameters is
derived through the Markov Chain Monte Carlo (MCMC) algorithm with the
NRLMSISE-00 model and the NRLMSIS 2.0 model as basis functions and the best-fit
density profiles are retrieved respectively. It is found that in the altitude
range of 105--200 km, the retrieved density profile is 88.8% of the density of
NRLMSISE-00 and 109.7% of the density of NRLMSIS 2.0 by fitting the lightcurve
in the energy range of 1.0--2.5 keV based on XEOS method. In the altitude range
of 95--125 km, the retrieved density profile is 81.0% of the density of
NRLMSISE-00 and 92.3% of the density of NRLMSIS 2.0 by fitting the lightcurve
in the energy range of 2.5--6.0 keV based on XEOS method. In the altitude range
of 85--110 km, the retrieved density profile is 87.7% of the density of
NRLMSISE-00 and 101.4% of the density of NRLMSIS 2.0 by fitting the lightcurve
in the energy range of 6.0--10.0 keV based on XEOS method. This study
demonstrates that the XEOS from the X-ray astronomical satellite Insight-HXMT
can provide an approach for the study of the upper atmosphere.Comment: 31 pages, 15 figures, 5 tables, accepted for publication in
Atmospheric Measurement Technique
High throughput quantitative reverse transcription PCR assays revealing over‐expression of cancer testis antigen genes in multiple myeloma stem cell‐like side population cells
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108270/1/bjh12951.pd
Inventarisasi Tanaman Peneduh Jalan Penjerap Timbal di Purwokerto
Tanaman peneduh jalan adalah tanaman yang berada di tepi jalan. Tanaman peneduh
jalan memiliki dua fungsi yaitu sebagai estetika dan ekologis. Salah satu fungsi ekologis
tanaman peneduh jalan adalah mengakumulasi bahan pencemar. Jenis pencemaran yang
memerlukan penanganan secara sistematis dan komprehensif adalah pencemaran timbal (Pb).
Pb banyak dihasilkan oleh aktivitas pembakaran bahan bakar minyak kendaraan bermotor. Jenis
tanaman peneduh jalan yang berpotensi mengakumulasi Pb belum tereksplorasi sehingga
dilakukan riset yang dapat menghasilkan database jenis spesies yang mampu mengurangi Pb di
lingkungan. Tujuan penelitian adalah menginventarisasi jenis tanaman peneduh jalan penjerap
Pb. Manfaat penelitian adalah mendapatkan jenis tanaman peneduh jalan yang berpotensi
penjerap Pb. Metode penelitian yang digunakan adalah survai di 8 (delapan) jalan di wilayah
Purwokerto. Sampel daun tanaman peneduh jalan diambil secara acak terpilih di sepanjang jalan
tersebut. Hasil penelitian menunjukkan jenis-jenis tanaman peneduh jalan yang berpotensi
menjerap Pb adalah Glodogan (Polyalthea longifolia), Angsana (Pterocarpus indicus), Filicium
(Filicium decipiends), Ketapang (Terminalia catappa), Beringin (Ficus benjamina), Kupu-kupu
(Bauhinia tomentosa), Puspa (Schima wallichii), Kenari (Canarium ovatum) dan Genitu
(Chrysophyllum cainito)
Cardiac dysfunction associated with consumptive hypothyroidism in a case of hepatic haemangioma
Not required for Clinical Vignette
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