388 research outputs found
Crescimento e acúmulo de macronutrientes na cultura do melão em Baraúna - RN e Petrolina - PE.
Com o objetivo de avaliar o crescimento e o acúmulo de nutrientes por híbridos de melão desenvolveram-se experimentos em área comercial no município de Baraúna-RN, e na estação experimental de Bebedouro (Petrolina-PE) da Embrapa Semiárido. Em Baraúna-RN, o experimento foi desenvolvido de setembro a novembro de 2010, e em Petrolina-PE, de agosto a outubro de 2010. O delineamento experimental foi em blocos casualizados completos, com quatro repetições, em esquema fatorial 2 x 5. Os tratamentos resultaram da combinação de dois híbridos de melão (Iracema e Gran Prix) e cinco épocas de coletas de plantas (15; 25; 35; 45 e 55 dias após o transplante, DAT). Para se fazer um programa de adubação na cultura do meloeiro, tanto do grupo Amarelo como do grupo Pele-de-Sapo, observou-se um crescimento lento no início, maior incremento da parte aérea de 35 a 45 DAT e maior exigência da planta para o estádio de frutificação de 35 a 45 DAT para `Iracema ́ e 45 a 55 DAT para `Gran Prix ́; Quanto ao acúmulo, para os dois materiais e nos dois locais, observou-se a seguinte ordem: K>N>P>Ca>Mg
Microfluidic-based platform to mimic the in vivo peripheral administration of neurotropic nanoparticles
Aim: Propose a nanoparticle for neuron-targeted retrograde gene delivery and describe a microfluidic-based culture system to provide insight into vector performance and safety. Methods: Using compartmentalized neuron cultures we dissected nanoparticle bioactivity upon delivery taking advantage of (quantitative) bioimaging tools. Results: Targeted and nontargeted nanoparticles were internalized at axon terminals and retrogradely transported to cell bodies at similar average velocities but the former have shown an axonal flux 2.7-times superior to nontargeted nanoparticles, suggesting an improved cargo-transportation efficiency. The peripheral administration of nanoparticles to axon terminals is nontoxic as compared with their direct administration to the cell body or whole neuron. Conclusion: A neuron-targeted nanoparticle system was put forward. Microfluidic-based neuron cultures are proposed as a powerful tool to investigate nanoparticle bio-performance.The work was financed by Portuguese funds through the FCT – Fundação para a Ciência e a Tecnologia in the framework of the projects PTDC/CTM-NAN/115124/2009 and PTDC/CTM-NAN/3547/2014. CDF Lopes, CP Gomes and E Neto acknowledge the FCT for their PhD scholarships(SFRH/BD/77933/2011, SFRH/BD/77930/2011 and SFRH/BD/81152/2011, respectively). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript
Crescimento e acúmulo de macronutrientes na cultura da cebola em Baraúna (RN) e Petrolina (PE).
Com o objetivo de avaliar o crescimento e o acúmulo de nutrientes por cultivares de cebola experimentos foram desenvolvidos na estação experimental de Bebedouro (Petrolina, PE) pertencente à Embrapa Semiárido, no período de maio a outubro de 2009 e em Baraúna, RN, em área comercial, no período de junho a outubro de 2009. O delineamento utilizado em cada experimento foi em blocos casualizados completos, com quatro repetições em esquema fatorial 2 x 6. Os tratamentos resultaram da combinação de duas cultivares de cebola (IPA 11 e Texas Grano 502) e seis épocas de coleta (15, 30, 45, 60, 75 e 90 DAT). Em cada coleta foram utilizadas seis plantas por repetição. A cebola, cultivares IPA 11 e Texas Grano, apresentou crescimento inicial lento intensificando-o a partir dos 30 dias após o transplantio. Maiores incrementos na matéria seca total, da parte aérea e do bulbo, ocorreram no período de 60 a 75 DAT. Os nutrientes foram absorvidos pela cebola na seguinte ordem: Ca > K > N > Mg > P e Ca > N > K > Mg > P para ?Texas Grano 502? e ?IPA 11? em Petrolina e K > Ca > N > Mg > P e N > K > Ca > Mg > P para Texas Grano 502 e IPA 11 em Baraúna. As cultivares Texas Grano 502 e IPA 11 exportaram mais nutrientes em Baraúna
Bidirectional flow of action potentials in axons drives activity dynamics in neuronal cultures
Objective. Recent technological advances are revealing the complex physiology of the axon and
challenging long-standing assumptions. Namely, while most action potential (AP) initiation occurs
at the axon initial segment in central nervous system neurons, initiation in distal parts of the axon
has been reported to occur in both physiological and pathological conditions. The functional role
of these ectopic APs, if exists, is still not clear, nor its impact on network activity dynamics.
Approach. Using an electrophysiology platform specifically designed for assessing axonal
conduction we show here for the first time regular and effective bidirectional axonal conduction in
hippocampal and dorsal root ganglia cultures. We investigate and characterize this bidirectional
propagation both in physiological conditions and after distal axotomy. Main results. A significant
fraction of APs are not coming from the canonical synapse-dendrite-soma signal flow, but instead
from signals originating at the distal axon. Importantly, antidromic APs may carry information
and can have a functional impact on the neuron, as they consistently depolarize the soma. Thus,
plasticity or gene transduction mechanisms triggered by soma depolarization can also be affected
by these antidromic APs. Conduction velocity is asymmetrical, with antidromic conduction being
slower than orthodromic. Significance. Altogether these findings have important implications for
the study of neuronal function in vitro, reshaping our understanding on how information flows in
neuronal cultures.info:eu-repo/semantics/publishedVersio
Efluxo de Co2 do Solo em uma Área de Bosque Localizada no Campus ii da UFPA, Santarém, PA
Este trabalho tem como objetivo determinar as trocas de CO2na interface solo-atmosfera. As medidas de CO2 foram realizadas porum analisador de gás por infravermelho (IRGA) LI-COR 6262, câmarasestática de concentração, conectado a um notebook. A média do fluxode CO2 para o solo seco e úmido foram 4,3 ± 1,0 μmol CO2 m-2 s-1 e 5,2± 1,8 μmol CO2 m-2 s-1, respectivamente. Essa diferença dos fluxos podeter sido devido à precipitação na área de estudo
Quantum Griffiths effects and smeared phase transitions in metals: theory and experiment
In this paper, we review theoretical and experimental research on rare region
effects at quantum phase transitions in disordered itinerant electron systems.
After summarizing a few basic concepts about phase transitions in the presence
of quenched randomness, we introduce the idea of rare regions and discuss their
importance. We then analyze in detail the different phenomena that can arise at
magnetic quantum phase transitions in disordered metals, including quantum
Griffiths singularities, smeared phase transitions, and cluster-glass
formation. For each scenario, we discuss the resulting phase diagram and
summarize the behavior of various observables. We then review several recent
experiments that provide examples of these rare region phenomena. We conclude
by discussing limitations of current approaches and open questions.Comment: 31 pages, 7 eps figures included, v2: discussion of the dissipative
Ising chain fixed, references added, v3: final version as publishe
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