4,250 research outputs found
5-ht inhibition of rat insulin 2 promoter cre recombinase transgene and proopiomelanocortin neuron excitability in the mouse arcuate nucleus
No full textA number of anti-obesity agents have been developed that enhance hypothalamic 5-HT transmission. Various studies have demonstrated that arcuate neurons, which express proopiomelanocortin peptides (POMC neurons), and neuropeptide Y with agouti-related protein (NPY/AgRP) neurons, are components of the hypothalamic circuits responsible for energy homeostasis. An additional arcuate neuron population, rat insulin 2 promoter Cre recombinase transgene (RIPCre) neurons, has recently been implicated in hypothalamic melanocortin circuits involved in energy balance. It is currently unclear how 5-HT modifies neuron excitability in these local arcuate neuronal circuits. We show that 5-HT alters the excitability of the majority of mouse arcuate RIPCre neurons, by either hyperpolarization and inhibition or depolarization and excitation. RIPCre neurons sensitive to 5-HT, predominantly exhibit hyperpolarization and pharmacological studies indicate that inhibition of neuronal firing is likely to be through 5-HT1F receptors increasing current through a voltage-dependent potassium conductance. Indeed, 5-HT1F receptor immunoreactivity co-localizes with RIPCre green fluorescent protein expression. A minority population of POMC neurons also respond to 5-HT by hyperpolarization, and this appears to be mediated by the same receptor-channel mechanism. As neither POMC nor RIPCre neuronal populations display a common electrical response to 5-HT, this may indicate that sub-divisions of POMC and RIPCre neurons exist, perhaps serving different outputs. (C) 2009 IBRO. Published by Elsevier Ltd. All rights reserved.</p
Effect of fenpropimorph, prochloraz and tebuconazole on growth and production of T-2 and HT-2 toxins by Fusarium langsethiae in oat-based medium.
No full textFusarium langsethiae has been isolated from infected cereals in central and
northern Europe where it has been identified in the last decade as the main
species involved in the occurrence of high levels of T-2 and HT-2 toxins, mainly
in oats. The efficacy of three fungicides (prochloraz, tebuconazole,
fenpropimorph) for controlling growth of two strains of F. langsethiae isolated
from oats was examined at 0.96 and 0.98 a(w) at 15, 20 and 25 °C on oat-based
media. The concentrations necessary for 50 and 90% growth inhibition (ED₅₀ and
ED₉₀ values) were determined. The effect on the trichothecene type A mycotoxins
T-2 and HT-2 was also determined. Without fungicides both strains grew faster at
0.98 than at 0.96 a(w) and the influence of temperature on growth rates was
25>20>15 °C. Prochloraz and tebuconazole were more effective than fenpropimorph
against F. langsethiae. Strain, temperature and type of fungicide significantly
influenced the ED₅₀ and ED₉₀ values for growth. The concentration ranges under
different environmental conditions were: prochloraz (0.03-0.1 and 0.3-1.5),
tebuconazole (0.06-0.9 and 1.3-8.2), and fenpropimorph (22-59 and 125-215 mg
l⁻¹). Production of T-2 and HT-2 toxins was influenced by temperature, a(w),
type of fungicide and dose. Levels of T-2 were usually higher than those of HT-
2 under the same conditions. The biosynthesis of T-2 toxin increased after 10
day incubation, but was reduced with decreasing temperature and increasing
fungicide dose. At 0.98 a(w) T-2 levels increased in cultures containing
fenpropimorph while at 0.96 a(w) the toxin concentrations increased in response
to the other two fungicides. Low doses of prochloraz or tebuconazole enhanced
toxin production when compared with untreated cultures for strain 2004-59 at
0.96 a(w) and 20-25 °C. HT-2 was hardly detectable in the treatments with
prochloraz or tebuconazole at 0.98 a(w). This is the first study on the effect
of these anti-fungal compounds on control of growth of F. langsethiae and on
production of T-2 and HT-2 tox
Topological Quantum Hashing with the Icosahedral Group
No full textWe study an efficient algorithm to hash any single qubit gate (or unitary matrix) into a braid of Fibonacci anyons represented by a product of icosahedral group elements. By representing the group elements by braid segments of different lengths, we introduce a series of pseudo-groups. Joining these braid segments in a renor- malization group fashion, we obtain a Gaussian unitary ensemble of random-matrix representations of braids. With braids of length O(log2(1/ε)), we can approximate all SU(2) matrices to an average error ε with a cost of O(log(1/ε)) in time. The algorithm is applicable to generic quantum compiling
Risk analysis of High-Temperature Aquifer Thermal Energy Storage (HT-ATES)
No full textThe storage of heat in aquifers, also referred to as Aquifer Thermal Energy Storage (ATES), bears a high potential to bridge the seasonal gap between periods of highest thermal energy demand and supply. With storage temperatures higher than 50 °C, High-Temperature (HT) ATES is capable to facilitate the integration of (non-)renewable heat sources into complex energy systems. While the complexity of ATES technology is positively correlated to the required storage temperature, HT-ATES faces multidisciplinary challenges and risks impeding a rapid market uptake worldwide. Therefore, the aim of this study is to provide an overview and analysis of these risks of HT-ATES to facilitate global technology adoption. Risk are identified considering experiences of past HT-ATES projects and analyzed by ATES and geothermal energy experts. An online survey among 38 international experts revealed that technical risks are expected to be less critical than legal, social and organizational risks. This is confirmed by the lessons learned from past HT-ATES projects, where high heat recovery values were achieved, and technical feasibility was demonstrated. Although HT-ATES is less flexible than competing technologies such as pits or buffer tanks, the main problems encountered are attributed to a loss of the heat source and fluctuating or decreasing heating demands. Considering that a HT-ATES system has a lifetime of more than 30 years, it is crucial to develop energy concepts which take into account the conditions both for heat sources and heat sinks. Finally, a site-specific risk analysis for HT-ATES in the city of Hamburg revealed that some risks strongly depend on local boundary conditions. A project-specific risk management is therefore indispensable and should be addressed in future research and project developments.Accepted Author ManuscriptWater Resource
Improving identification of HT-ATES performance drivers and -barriers
No full textHigh temperature aquifer thermal energy storage (HT-ATES) can potentially solve the mismatch between heat supply and demand. It can provide a large scale seasonal heat storage solution. Thereby it enables an increase in full load hours of the base heat source, which can benefit project performance on both costs and emissions. However, the limited number of successful pilot projects indicates the technology has not escaped its state of infancy. There is a gap from concept to implementation, which is signified by the disagreement of experts on performance drivers and barriers of HT-ATES. This research aims to narrow the described knowledge gap, by improving identification of HT-ATES performance drivers and barriers. Thereby it strives to improve decision making of HT-ATES implementation, and further enhance future HT-ATES application in heating projects. The broad scope of research demands both a diagnostic and design-orientated approach, and fits seamlessly with a multi-criteria decision analysis. The analysis entails the stages of creating, evaluating, comparing and ranking of case-specific scenarios. Parametric variation changes the conditions for HT-ATES implementation across the scenarios. A simulation model is developed and connected to a groundwater model to apply the parametric variation, to create the different scenarios, and consequently to produce the quantitative information for further evaluation. During the stages of creating, evaluating, comparing and ranking, the methodology systematically produces new results on the opportunities and risks introduced by HT-ATES, and additionally on the HT-ATES performance drivers and barriers. The results show that HT-ATES enables the opportunity of improving project performance with respect to the internal rate of return and emissions. Groundwater impact remains the greatest risk, but it can be minimised with smart decision making. To support the decision maker and to overcome the risk of groundwater impact, the research proposes several performance-enhancing, non-explicit guidelines. The guidelines focus on realising an HT-ATES implementation, where project performance with respect to internal rate of return, emissions and groundwater impact are balanced. Thereby they explain the major HT-ATES performance drivers and barriers. The guidelines are summarised below. The decision maker is recommended to .. 1. .. minimise the uncertainty, through thorough subsurface characterization before implementation. Secondly, to focus on aquifers with a minimum depth of 200 [m] and a minimum hydraulic conductivity of 5 [m/d] 2. .. assure network return temperatures during peak demand are below expected storage temperatures 3. .. not consider project life-times exceeding 20 years 4. .. assure yearly maximum base source heat production is always lower than yearly consumer heat demand 5. .. to strive for a flat demand curve and apply peak-shaving, by means of, for example, variable heat prices Currently, the guidelines have the purpose of giving direction to the decision maker, but they will become more explicit once the methodology is improved, and the uncertainty and number of assumptions in the model is decreased.Electrical Engineering | Sustainable Energy Technolog
O papel dos receptores 5-HT1A nas respostas ingestivas e hipnogênica provocadas pela injeção intracerebroventricular de serotonina em pombos (Columba livia): discriminação entre receptores pré e pós-sinápticos
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas, Programa de Pós-Graduação em Neurociências, Florianópolis, 2014.Introdução: diversos estudos demonstram que os circuitos serotonérgicos inibem a ingestão de alimentos e o sono em aves e mamíferos. A injeção intracerebroventricular (ICV) de 5-HT em pombos, entretanto, provoca efeitos diferentes: aumento na ingestão de água e na duração do sono. Nós associamos estas respostas à atuação de receptores 5-HT1A, pois a ativação destes receptores produz respostas similares. No entanto, os receptores 5-HT1A podem estar localizados no neurônio serotonérgico (autorreceptores) ou em outros neurônios (heterorreceptores). Dependendo da sua localização, a ativação destes receptores produz efeitos diferentes. Portanto, o nosso objetivo foi avaliar a participação dos receptores 5-HT1A nas respostas dipsogênica e hipnogênica provocadas pela 5-HT, na tentativa de especificar as respostas desencadeadas pela 5-HT à atuação de auto ou heterorreceptores. Métodos: os animais (pombos adultos, Columba lívia, de ambos os sexos, pesando entre 400-550 g) foram divididos em 5 grupos/experimentos diferentes. Experimento 1: 16 pombos foram divididos em dois grupos de acordo com o pré-tratamento e receberam: MM77 (antagonista de heterorreceptores 5-HT1A; 0, 23 ou 69 nmol), ou WAY100635 (WAY, antagonista de auto e heterorreceptores 5-HT1A; 0, 0,1, 0,3 ou 1 nmol) e 20 min. após foram tratados com 5-HT (50 e 150 nmol) ou 8-OH-DPAT (30 nmol; agonista de receptores 5-HT1A/7). Logo após o tratamento, o registro comportamental começou e a ingestão de alimentos foi verificada 60 min. após a última injeção. Experimento 2: 12 pombos foram divididos em 2 grupos e submetidos à cirurgia para injeção ICV (bilateral) da neurotoxina de neurônios serotonérgicos 5,7-dihidroxitriptamina (5,7-DHT, 200µg/injeção) ou de seu veículo. Após 12 dias, os animais começaram a ser testados com 5-HT (150 nmol), 8-OH-DPAT (30 nmol) ou veículo (ácido ascórbico 1% em NaCl 0,9%) com intervalo de 7 dias entre as injeções. Estes animais foram mortos 28 dias após a cirurgia e o conteúdo encefálico de 5-HT foi analisado para verificar os efeitos da lesão. Adicionalmente, nós utilizamos outros 18 animais divididos em três grupos, a) 6 animais naïve que foram mortos para servir como controle para os níveis basais de 5-HT e outros dois grupos (N: 6/grupo) que foram submetidos à cirurgia (injeção de 5,7-DHT ou do veículo) e perfundidos 12 dias após a cirurgia para verificar os efeitos da toxina sobre a densidade de neurônios serotonérgicos. Experimento 3: Secções do tronco e do hipotálamo de 6 animais não submetidos a qualquer manipulação experimental foram processados pela técnica de autorradiografia para detectar a distribuição dos sítios de ligação ao agonista tritiado [3H] 8-OH-DPAT. Experimento 4: 15 pombos com cânulas guia direcionadas ao ventrículo lateral direito foram divididos em 3 grupos e tratados com: 8-OH-DPAT (30 nmol) e tiveram livre acesso (N:5) ou foram privados de água após a injeção (N:5) e veículo (N:5). 90 min. após a injeção os animais foram perfundidos e as secções do tronco encefálico processadas para detecção da proteína Fos em neurônios serotonérgicos e não serotonérgicos, e secções do hipotálamo processadas para detectar somente a expressão da proteína Fos. Experimento 5: 10 pombos com cânulas guia direcionadas ao ventrículo lateral direito foram divididos em 3 grupos e tratados com: 5-HT (150 nmol) e tiveram livre acesso (N:5) ou foram privados de água após a injeção (N:5). 90 min. após, os animais foram perfundidos e secções contendo o hipotálamo foram processadas para a detecção da proteína Fos. Resultados: tanto a 5-HT como o 8-OH-DPAT provocaram intensa ingestão de água e aumento na duração do sono. O 8-OH-DPAT ainda aumentou a ingestão de alimento. Os efeitos ingestivos e hipnogênico dos tratamentos foram parcial ou totalmente afetados pelos antagonistas evidenciando a participação dos receptores 5-HT1A nas alterações comportamentais provocadas pela 5-HT. Entretanto, os dados farmacológicos não nos permitiram especificar entre a ação de auto ou heterorreceptores, mas indicam que a interação entre os dois receptores parece ser um importante aspecto do controle exercido pelos circuitos serotonérgicos sobre os comportamentos ingestivos. Apesar de diminuir drasticamente a densidade de neurônios serotonérgicos, a lesão não afetou as alterações provocadas pelos tratamentos o que sugere que em animais com a função serotonérgica prejudicada, receptores 5-HT1A localizados em neurônios não serotonérgicos parecem ser os responsáveis pelos efeitos dos tratamentos. Além disso, os antagonistas e a lesão dos neurônios serotonérgicos também aumentaram o sono dos animais indicando um efeito inibitório tônico dos neurônios serotonérgicos sobre o sono. Os tratamentos também aumentaram a atividade Fos em regiões hipotalâmicas ricas em receptores 5-HT1A e que parecem estar envolvidas com o controle da ingestão de alimento, dos fluídos corporais e do sono. Conclusão: As respostas dipsogênica e hipnogênica desencadeadas pela injeção de 5-HT parecem ser mediadas parcialmente tanto por auto como por heterorreceptores 5-HT1A. Aparentemente, estas respostas são mediadas por receptores 5-HT1A localizados em estruturas encefálicas (no tronco e no hipotálamo) envolvidas com o controle dos comportamentos ingestivos e de sono em aves. Nossos resultados revelaram sutis diferenças na atividade celular produzidas pela 5-HT e pelo 8-OH-DPAT que sugerem que outros receptores serotonérgicos também participam das respostas comportamentais organizadas pela 5-HT. Além disso, os resultados obtidos com a lesão sugerem que os receptores 5-HT1A parecem apresentar diferenças funcionais espécie-específicas, o que pode ser reflexo de diferentes pressões seletivas experimentadas por aves e mamíferos ao longo da evolução dos vertebrados.Abstract : Introduction: several studies have demonstrated the inhibitory role of serotonergic circuits on ingestive and sleep behaviors both in mammals and birds. Intracerebroventricular (ICV) injections of serotonin (5-HT), however, evoked oposite effects: increased water intake and sleep. We associated these responses to 5-HT1A receptors, because the activation of these receptors caused similar responses. However, the 5-HT1A receptor is located on serotonergic neurons (as autoreceptor) as well as on different neurons (as heteroreceptor), and produces different effects based on its location. Therefore, we decided to investigate the participation of 5-HT1A receptor on dipsogenic and hypnogenic 5-HT-mediated responses to try discriminate the role of auto and heteroreceptors. Methods: the animals (adult pigeons, Columba lívia, both sex, 400-550g of body weight) were divided in 5 groups. Each group represented one different experiment. Experiment 1: 16 pigeons were divided in two groups according on the antagonist used as pretreatment and were injected with: MM77 (0, 23 or 69 nmol, heteroreceptor antagonist), or WAY100635 (WAY, 0, 0.1, 0.3 or 1 nmol, 5-HT1A auto and heterorreceptor antagonist) and 20 min. afterwards injected with 5-HT (0, 50 or 150 nmol) or 8-OH-DPAT (30 nmol). The animals behaviors were registered during the first hour after the last injection and the food and water intake was evaluated at the end of this period. Experiment 2: 12 pigeons were divided in 2 groups and were stereotaxically implanted with an ICV cannula guide (bilateral) to receive the serotonergic neurotoxin 5,7-Dihydroxytryptamine (5,7-DHT, 200µg/injection) or its vehicle. Past 12 days the tests with 5-HT (150 nmol), 8-OH-DPAT (30 nmol) or vehicle (1% ascorbic acid in 0.9 NaCl) started, with seven days apart each other. These animals were killed 28 days after the surgery and the encephalic levels of 5-HT were analised to verify possible degenerative effects of 5,7-DHT. Moreover, we used other 18 animals divided in three groups, a) six naïve pigeons that were killed to be used as reference of the basal levels of 5-HT and another 2 groups that were inject with 5.7-DHT (N: 6) or its vehicle (N:6) and were perfused 12 days later to verify the 5,7-DHT effects on serotonergic neurons. Experiment 3: six naïve pigeons were killed and had their brains dissecated and brainstem and hypothalamic sections reacted by autoradiographic approach to demonstrate the distribution of 5-HT1A binding sites with the selective radioligand [3H] 8-OH-DPAT. Experiment 4: 15 pigeons with ICV cannula guide implanted were divided in three groups and treated with: 8-OH-DPAT (30 nmol) withfree (N:5) or without acess to water after the injection (N:5), and vehicle (N:5). 90 min. later the animals were perfused and brainstem sections reacted to detect Fos protein expression in serotonergic and in non-serotonergic neurons, and hypothalamic sections processed to detect Fos activation. Experiment 5: 10 pigeons with ICV cannula guide implanted were divided in three groups and treated with: 5-HT (150 nmol) with free (N:5) or without acess to water after the injection (N:5). 90 min. later the animals were perfused and hypothalamic sections processed to detect the Fos activation. Results: both 5-HT and 8-OH-DPAT evoked huge increase in water intake and sleep duration. The 8-OH-DPAT injection also produce hyperphagic responses. The ingestive and hypnogenic effects of the treatments were partially or totally inhibited by the antagonists, sugesting the participation of 5-HT1A receptors on behavioral changes produced by 5-HT. However, the pharmacologic data did not permit specify between the action of 5-HT1A auto or heteroreceptors, but indicate the interaction between these two receptors as an important aspect of serotonergic control upon ingestive behavior. Besides its impressive effects on serotonergic neurons density, the 5,7-DHT lesion did not affect the behavioral changes caused by the treatments, suggesting that in animals with anormal serotonergic function, 5-HT1A receptors located in non-serotonergic neurons seem to be related to the treatments effects. Additionally, the antagonists and the 5,7-DHT lesion increased the sleep, indicating one tonic inhibitory effect of serotonergic circuits on sleep. The treatments also increased the Fos protein activation in hypothalamic regions with high 5-HT1A binding sites density that seem to be involved with food, body fluid and sleep regulation. Conclusion: the dipsogenic and hypnogenic responses evoked by 5-HT seem to be mediated partially by both 5-HT1A auto and heteroreceptors. Apparently, these responses are regulated by 5-HT1A receptors located on encephalic (hypothalamic and brainstem) regions directly or indirectly involved with ingestive and sleep/wake cycle regulation in birds. Our results also indicate small differences in the neuronal activity evoked by 5-HT and by 8-OH-DPAT suggesting that other serotonergic receptor also participate in behavioral responses organized by 5-HT. Moreover, the results produced by 5,7-DHT lesion indicate that 5-HT1A receptors seem present specie-specific functional differences that could represent different seletive pressions experimented by birds and mammal during vertebrate evolution
Transforming Ates To Ht-Ates, Insights From Dutch Pilot Project
No full textAquifer Thermal Energy Storage (ATES) systems combined with a heat pump save energy for space heating and cooling of buildings. In most countries the temperature of the stored heat is allowed up to 25-30°C. However, when heat is available at higher temperatures (e.g. waste heat, solar heat), it is more efficient to store higher temperatures because that improves heat pump performance or makes it unnecessary. Therefore, interest in HT-ATES development is growing. Next to developing new HT-ATES projects, there is also a large potential for additional energy savings by transforming ‘regular’ low-temperature LT-ATES systems to a HT-ATES. Such a transformation is tested for a greenhouse system in the Netherlands. This greenhouse has a LT-ATES system operational since 2012, and from 2015 onwards heat is stored in the warm well at temperatures up to 45°C. In this HT-ATES transformation pilot, water quality parameters are closely monitored as well as temperature distribution in the subsurface (using DTS). Together with the operators, the results from the ATES monitoring are used to continuously improve system performance. Numerical groundwater and heat flow simulations of actual and expected well pumping data are used to evaluate how well operation can be optimized. In this paper, the optimization using monitoring results and simulations is discussed as well as general and site specific lessons/conclusions for such transformations.Water Resource
Expression of <i>EjMYB</i> genes in response to 0°C (Control), HT and LTC treatments.
No full textHT, heat treatment; LTC, low temperature conditioning. All of the materials were obtained from Xu et al., (2014). mRNA levels were expressed as a ratio relative to the harvest time point (0 d), which was set at 1. Error bars indicate S.E.s from three replicates.</p
Presença de receptores serotonérgicos no núcleo paraventricular do hipotálamo e sua participação no controle neural da ingestão de alimentos em pombos (Columba livia)
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas. Mestrado em NeurociênciasInvestigação do possível envolvimento de receptores serotonérgicos presentes no Núcleo Paraventricular do Hipotálamo na regulação de comportamentos ingestivos e não ingestivos, após a administração de serotonina (5-HT) ou de metergolina (antagonista não seletivo de receptores serotonérgicos
Metabolic and serotonergic modulation of hypothalamic arcuate nucleus neurones in vitro
No full text1. The effects of glucose on the electrophysiological properties of rat hypothalamic arcuate nucleus (ARC) neurones were investigated. Neurones were recorded in 10 mM (hyperglycaemic) and 2 mM (euglycaemic) glucose-containing aCSF. The major findings were that input resistance increased in 10 mM glucose, there was an increase in the activity of neurones in 2 mM glucose and there were a greater percentage of neurones expressing lh in 10 mM glucose. Subthreshold active conductances were differentially expressed in ARC neurones including: anomalous inward rectification Q. ), time- and voltage-dependent inward rectification 00, A-like transient outward rectification (IA) and T-type calcium-like conductance. Characterisation of the differential expression of these conductances may represent one way of functionally classifying ARC neurones.
2. Whole-cell patch clamp recording techniques were used in isolated hypothalamic brain slice preparations to investigate the effects of 5-HT on ARC neurones. Bath application of 5-HT induced a membrane depolarisation in a sub-population of ARC neurones (30%), a response that persisted in the presence of TTX indicating a direct effect. 5-HT excited ARC neurones through three potential mechanisms: closure of one or more resting potassium conductances; activation of a non-selective cation channel, or a combination of the two; or activation of a pump in the membrane. This response was mediated through the 5-HT2A. 5-HT2B and/or 5-HT2C receptors revealed using a range of 5-HT receptor agonists and antagonists. 5-HT was shown to excite CART-expressing neurones suggesting an anorexigenic role for 5-HT, via 5-HT2 receptors at the level of the ARC.
3.5-HT induced a membrane hyperpolarisation in a sub-population of ARC neurones (37%). The 5-HT-induced hyperpolarisation persisted in the presence of TTX indicating a direct effect on ARC neurones. 5-HT inhibited ARC neurones most likely through the activation of one or more potassium conductances,including an inwardly rectifying potassium conductance. Potential roles for 5-HTIA, 5-HTIB and 5-HT7 receptors were suggested from studies utilising 5-HT receptor agonists and antagonists. 5-HT inhibited orexigenic NPY/AgRP neurones, identified by their response to ghrelin and by their electrophysiological properties, suggesting an anorexigenic role for 5-HT, acting via 5-HTI and 5-HT7 receptors on NPY/AgRP neurones at the level of the ARC.
4. The effects of feeding-related signals on hypothalamic neuropeptide expression were investigated using real-time-PCR. A new protocol measuring gene expression from hypothalamic explants was developed. Effects of GABA and AMPA on c-fos expression were investigated and subsequent studies showed leptin and glucose modulated the expression of NPY, POMC and AgRP, in fed and fasted animals. Further work is required to validate this novel approach to studying the central control of energy balance
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