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Search Results: 1 - 10 of 508 matches for " emergence "
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Effect of Mercuric Compounds on Pine and Sycamore Germination and Early Survival  [PDF]
Sharon R. Jean-Philippe, Nicole Labbé, Jeremie Damay, Jennifer A. Franklin, Karen Hughes
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.31017
Abstract: Mercury pollution has become an important current issue as a result of its environmental effects on a global scale. The Oak Ridge Reservation, established in 1942, was the designated site for the construction of the atomic bomb. During a 20-year period from 1944-1963 radioactive and toxic chemical pollutants, especially mercury compounds were released into the surrounding waterways.A germination study was conducted to investigate the ability of three tree species, American sycamore (Platanus occidentalis),shortleaf pine (Pinus echinata), and loblolly pine (Pinus taeda) seeds to germinate in mercuric nitrate (Hg(NO3)2 and methylmercury chloride (CH3HgCl) solutions. A subsequent greenhouse study was conducted to assess the phytotoxic effects of different mercuric solutions on Platanus occidentalis (American Sycamore), inoculated with soils from East Fork Poplar Creek.We also measured vegetation stress by Near Infrared (NIR) spectroscopy.The wavelengths examined were those thatare specific to chlorophyll and several carotenoids, which are involved in photosynthesis: 430 nm (Chl a), 448 nm (Chl b, carotenoids), 471 nm (carotenoids), 642 nm (Chl b), 662 & 680 nm (Chl a). Principal component analysis (PCA) was performed to identify patterns in sycamore leaf spectral data.Under in vitro conditions, as mercury concentration increased above 100 mg·kg-1, germination of all species decreased, with P. echinata being the least sensitive. Germination was inhibited more when seeds were exposed to methyl mercury chloride than to mercuric nitrate. Organic species of mercury proved to be more toxic than inorganic species of mercury in our greenhouse study. Significant changes occurred in levels of all pigments sampled (p430, p448, p471, p642, p662, and p680) over the course of the experiment. NIR spectroscopy was not sensitive enough to detect other chemical changes to foliage following mercury application.
Development of Hydropriming Techniques for Sowing Seeds of Upland Rice in Uganda  [PDF]
Yoshihiro Nakao, Godfrey Asea, Yoshino Minoru, Kojima Nobuki, Hanada Hiroyuki, Miyamoto Kisho, Shin Yabuta, Kamioka Rieko, Sakagami Jun-Ichi
American Journal of Plant Sciences (AJPS) , 2018, DOI: 10.4236/ajps.2018.911157
Abstract: Hydropriming is one of the presoaking, seed priming technique that allows seeds to imbibe water and go through the first stage of germination but does not allow radicle appearance. After water imbibition, seeds are dried to their original weight. This technique is used to help crops overcome environment stress. This study aims to assess the morphological traits of farmer’s seeds for developing priming treatments so as to develop appropriate methods to maximize the effect of hydropriming. We collected farmer’s samples of rice sowing seeds grown indifferent regions of Ugandan. For each sample, distribution of the seed density in percentages was calculated. Secondly, germination tests as per seed density levels and as per farmer’s seed samples were conducted for deciding appropriate priming treatment. Finally, wooden boxes experiment was conducted to confirm priming effects. As the result, it was observed that the difference in seed density levels affects the quality of farmer’s seeds, as observed in the case of NERICA4. If the radicle appears during soaking period, the newly developed radicle dies during the seed drying process in the hydropriming treatment. Seed germination was observed after 24 h of sowing at room temperature, even at a seed density level of 1.17, which is vigorous for germination. Consequently, farmer’s seeds were soaked for 24 h to promote water absorption and activate metabolic pathways and to avoid germination failure when seeds are dried to their initial weight. After hydropriming treatment, plant growth was improved. Alternatively, significant difference was not observed in the mean emergence time between hydroprimed and unprimed seeds. These results suggest that priming the seeds by soaking for 24 h and drying to their initial weight considerably affects initial growth after emergence under dry soil condition.
Rice Husk Biochar Influences Seedling Emergence of Junglerice (Echinochloa colona) and Herbicide Efficacy  [PDF]
Bhagirath S. Chauhan
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.47164
Abstract:

The use of carbonized rice husk biochar improves the fertility and productivity of poor soils in rice-based cropping systems. However, biochar may also influence weed seedling emergence and the efficacy of soil-applied herbicides. Experiments were conducted in a screenhouse to evaluate the effect of biochar rates (0, 20, 40, and 80 t·ha?1) and seed burial depth (0, 1, and 2 cm) on seedling emergence of junglerice (Echinochloa colona) and the effect of biochar rates and pendimethalin (0, 500, 1000, and 1500 g·a.i.·ha?1) and pretilachlor doses (0, 300, 600, and 900 g·a.i.·ha?1) on seedling emergence and seedling biomass of junglerice. Data were analyzed using nonlinear regression. The burial depth to inhibit 50% of maximum seedling emergence was 0.76 cm when biochar was not added to soil and the depth increased with an increase in biochar rates for soil. Similarly, compared with the soil with no biochar, the use of bichoar increased the pretilachlor dose to inhibit 50% of maximum emergence or biomass. The pretilachlor dose to inhibit 50% of maximum biomass of junglerice was 100, 130, 240, and

Causal Groupoid Symmetries  [PDF]
Sergio Pissanetzky
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.54059
Abstract:

Proposed here is a new framework for the analysis of complex systems as a non-explicitly programmed mathematical hierarchy of subsystems using only the fundamental principle of causality, the mathematics of groupoid symmetries, and a basic causal metric needed to support measurement in Physics. The complex system is described as a discrete set S of state variables. Causality is described by an acyclic partial order w on S, and is considered as a constraint on the set of allowed state transitions. Causal set (S, w) is the mathematical model of the system. The dynamics it describes is uncertain. Consequently, we focus on invariants, particularly group-theoretical block systems. The symmetry of S by itself is characterized by its symmetric group, which generates a trivial block system over S. The constraint of causality breaks this symmetry and degrades it to that of a groupoid, which may yield a non-trivial block system on S. In addition, partial order w determines a partial order for the blocks, and the set of blocks becomes a causal set with its own, smaller block system. Recursion yields a multilevel hierarchy of invariant blocks over S with the properties of a scale-free mathematical fractal. This is the invariant being sought. The finding hints at a deep connection between the principle of causality and a class of poorly understood phenomena characterized by the formation of hierarchies of patterns, such as emergence, selforganization, adaptation, intelligence, and semantics. The theory and a thought experiment are discussed and previous evidence is referenced. Several predictions in the human brain are confirmed with wide experimental bases. Applications are anticipated in many disciplines, including Biology, Neuroscience, Computation, Artificial Intelligence, and areas of Engineering such as system autonomy, robotics, systems integration, and image and voice recognition.

First Evidence of Hantavirus in Central Iran as an Emerging Viral Disease  [PDF]
Sadegh Chinikar, Abbas Ali Javadi, Arash Hajiannia, Behroz Ataei, Tahmineh Jalali, Sahar Khakifirouz, Norbert Nowotny, Jonas Schmidt-Chanasit
Advances in Infectious Diseases (AID) , 2014, DOI: 10.4236/aid.2014.44024
Abstract:

Hantavirus is a zoonosis transmitted from rodents to humans. Asymptomatic infected rodents can secrete hantaviruses in the urine, feces, and saliva. The main route of infection transmission to human is aerosols contaminated with the virus. This study was designed to evaluate the serological and molecular prevalence of hantavirus as an emerging zoonoses disease among street sweepers in Isfahan province, central Iran. Serum samples from 200 street sweepers in healthy condition and those with recent renal failure were tested by ELISA (IgM and IgG). Molecular analysis was subsequently applied for IgM positive cases. From these samples, 9 (4.5%) were positive, of which 2 (22.22%) were positive for both IgM and RT-PCR, while 7 (77.77%) were positive for IgG. The mean age and work experience of the positive cases were 39.7 and 11.5 respectively. According to our observations, all positive cases reported prevalence of rodents in their work place. The logistic regression test showed that the age and work experience were not risk factors for being positive, but prevalence of rodents in work place was a risk factor for being positive, when compared with negative cases. This is the first comprehensive study on the prevalence of hantavirus with positive results coming from Iranian population, which can raise the public awareness for the hantavirus infections as a public health threat.

Evaluation of a Metabolic Cotton Seedling Emergence Model  [PDF]
Dennis C. Gitz III, Jeffrey T. Baker, James R. Mahan
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.611172
Abstract: A model for cotton seedling emergence (MaGi) based on malate synthase kinetics was evaluated. Cotton seeds were planted through the early spring and into typical planting times for the areas. Soil temperatures at seed depth were used as inputs into MaGi and a commonly used seedling emergence model based on heat unit accumulation (DD60). Time to 50% emergence was calculated and compared with predicted emergence using MaGi and DD60. MaGi yielded predictive capability without the need to resort to lengthy experimentation required by traditional methods. The results suggest that a physiological or semi-empirical approach incorporating both enzyme kinetics and whole plant temperature responses would be useful for rapidly constructing seedling emergence models.
Prospective, Randomized Comparisons of Induction of Anesthesia with Ketamine, Propofol and Sevoflurane for Quality of Recovery from Short Sevoflurane Anesthesia in Pediatric Patients  [PDF]
Shin Nakayama, Hajime Furukawa, Hiromune Yanai
Open Journal of Anesthesiology (OJAnes) , 2015, DOI: 10.4236/ojanes.2015.57029
Abstract: Background: Emergence agitation (EA) after sevoflurane anesthesia is common in children. When rapid intravenous induction of general anesthesia is indicated in a brief procedure, the induction agent can reduce the incidence of EA after sevoflurane anesthesia. The aim of this study was to compare the efficacy of intravenous induction with ketamine and propofol for reducing EA in children after short sevoflurane anesthesia. Methods: Children aged 2 to 6 years who were scheduled to undergo inguinal hernia repair were randomly divided into 3 groups to receive 2 mg/kg ketamine iv, 3 mg/kg propofol iv, or inspired concentration of 8% sevoflurane for induction of anesthesia. After a laryngeal mask airway (LMA) insertion, a caudal block was performed in all children. Anesthesia was maintained with 1.5% sevoflurane and 65% nitrous oxide in oxygen with spontaneous ventilation. The recovery characteristics were recorded and EA were evaluated by using the Pediatric Anesthesia Emergence Delirium (PAED) scale. Results: One hundred and twenty children were enrolled and randomized to treatment. Children who received ketamine induction had higher incidence of EA than those who received propofol (42% vs 16%, P < 0.05) and showed delayed recovery (32 ± 9 min) as compared with those who received propofol or sevoflurane (22 ± 8 min and 20 ± 7 min, respectively, P < 0.05). The mean peak PAED score was significantly lower in children who received propofol induction (6.8 ± 4.0, P < 0.05) than ketamine (11.8 ± 4.1) or sevoflurane (11.6 ± 3.8). Conclusions: Intravenous induction with ketamine does not prevent the incidence of EA and delays recovery. Induction with propofol improves the quality of recovery by reducing the incidence of EA and provides a safe and early recovery.
Control of Glyphosate-Resistant Giant Ragweed (Ambrosia trifida L.) with 2,4-D Followed by Pre-Emergence or Post-Emergence Herbicides in Glyphosate-Resistant Soybean (Glycine max L.)  [PDF]
Amit J. Jhala, Lowell D. Sandell, Greg R. Kruger
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.515243
Abstract:

Control of glyphosate-resistant giant ragweed is a challenge, particularly for soybean growers, because of limited effective post-emergence (POST) herbicide options. Many soybean growers in no-till production systems use 2,4-D in burndown application for control of broadleaf weeds, including giant ragweed. Field experiments were conducted at David City, NE, in 2012 and 2013 to evaluate 2,4-D followed by PRE or POST herbicide programs for control of glyphosate-resistant giant ragweed in glyphosate-resistant soybean. Results suggested that burndown application of 2,4-D or saflufenacil plus imazethapyr resulted in 89 to 99% control of giant ragweed at 21 days after treatment. Burndown-only treatments of S-metolachlor plus metribuzin or sulfentrazone plus cloransulam resulted in poor control (≤65%) of giant ragweed and reduced soybean yield (≤ 577 kg·ha-1). Burndown application of 2,4-D followed by saflufenacil plus imazethapyr, S-metolachlor plus metribuzin, or sulfentrazone plus cloransulam applied pre-emergence (PRE) or cloransulam, chlorimuron, fomesafen, imazethapyr, or lactofen in tank-mixtures with acetochlor applied POST resulted in 87% to 99% giant ragweed control, reduced density to ≤7 plants m-2, and resulted in soybean yield from 2519 to 3823 kg·ha-1. There was no difference among and between 2,4-D followed by PRE or POST herbicides for giant ragweed control, density, or soybean yield, indicating all the two pass herbicide programs were effective. It is concluded that glyphosate-resistant giant ragweed can be effectively controlled in soybean by including 2,4-D in burndown program followed by PRE or POST herbicides tested in this study.

Efeito da compacta??o do solo sobre a semente no desenvolvimento da cultura do feij?o
Modolo, Alcir José;Trogello, Emerson;Nunes, Anderson Luis;Silveira, Jo?o Cleber Modernel da;Kolling, Evandro Marcos;
Acta Scientiarum. Agronomy , 2011, DOI: 10.4025/actasciagron.v33i1.4236
Abstract: one of the factors of low productivity is the difficulty of establishing the ideal population of plants at sowing time, due to the several factors that prevent the normal germination of part of the seeds. among the primordial factors for germination are humidity, temperature, and airing of the soil. it is important to mention that these factors are directly influenced by the state of soil compaction around the seed. the present work aimed to study the effects of the combination between depths of sowing and loads applied by press wheel of the seeder on the emergence and development of bean culture, in no-tillage systems. the factorial scheme was applied, at the delineation in random blocks composed of twelve treatments (three depths of sowing and four levels of loads applied by the press wheel) and four replications. the results showed that the sowing performed at 5.0 cm of depth presented the best index of speed emergence when compared to the depths of 3.0 and 7.0 cm.
Efeito de rodas compactadoras submetidas a cargas verticais em profundidades de semeadura sobre o desenvolvimento do milho
Silva, Rouverson P. da;Corá, José E.;Carvalho Filho, Alberto;Lopes, Afonso;Furlani, Carlos E. A.;
Engenharia Agrícola , 2004, DOI: 10.1590/S0100-69162004000200019
Abstract: the success of the establishment of a crop depend on several factors and the seeders press wheels should be capable to improve the contact soil-seed in order to promote good seed germination. the present work had as objective to study the influence of three models of press wheel, three depths of sowing and three load levels on the press wheel on the germination and development of the corn grow, in a projected sowing assay lane for this purpose. the experiment was carried out at municipal district of uberaba - mg, brazil, in a split plot array, with 27 treatments and four replications, used to evaluate agronomic characteristics of the corn crop. the results evidenced that the depth of sowing was the factor that more affected the vegetative development of the corn crop in the stadium 2, and none of the evaluated characteristics in the stadium 4 had significant differences in the measures of the corn development.
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