3,396 research outputs found
Replica symmetric evaluation of the information transfer in a two-layer network in presence of continuous+discrete stimuli
In a previous report we have evaluated analytically the mutual information
between the firing rates of N independent units and a set of multi-dimensional
continuous+discrete stimuli, for a finite population size and in the limit of
large noise. Here, we extend the analysis to the case of two interconnected
populations, where input units activate output ones via gaussian weights and a
threshold linear transfer function. We evaluate the information carried by a
population of M output units, again about continuous+discrete correlates. The
mutual information is evaluated solving saddle point equations under the
assumption of replica symmetry, a method which, by taking into account only the
term linear in N of the input information, is equivalent to assuming the noise
to be large. Within this limitation, we analyze the dependence of the
information on the ratio M/N, on the selectivity of the input units and on the
level of the output noise. We show analytically, and confirm numerically, that
in the limit of a linear transfer function and of a small ratio between output
and input noise, the output information approaches asymptotically the
information carried in input. Finally, we show that the information loss in
output does not depend much on the structure of the stimulus, whether purely
continuous, purely discrete or mixed, but only on the position of the threshold
nonlinearity, and on the ratio between input and output noise.Comment: 19 pages, 4 figure
Functional needs, emotions, and perceptions of coffee consumers and non-consumers
Coffee is one of the most consumed beverages worldwide. Over the last decades coffee has become a specialty product. Drinking a coffee beverage entails several mixed factors, such as pleasure, experience, lifestyle, and social status. It can also provide an emotional pick-up, both mentally and physically. Only a few studies have explored the motives and emotions of coffee consumption and not consumption. There is limited understanding of consumers' emotional approach towards coffee, and what influences a positive and negative inclination towards coffee consumption. This research fills the current research gaps by addressing three main questions: (i) What are the emotions and habits of coffee consumption? (ii) What are the motives of coffee consumption and non-consumption? and (iii) How relevant is the coffee health impact perception of consuming or not consuming coffee? The research activities include 467 face-to-face interviews with consumers. Interviews are performed in two different countries, Italy and Portugal. Data elaboration includes a principal component analysis carried out to identify latent factors on motives and emotions of consumption in both national groups, and to explore the relationship between the main emotions and consumers' habits and socio-economic characteristics. Results support that consumers have positive emotions from coffee consumption. Perceived emotions are energy, satisfaction, and pleasure. Non-consumption is mainly driven by taste and fear of coffee's health impacts. There are limited differences in the countries analysed. Socio-economic characteristics limitedly influence perceived emotions and consumption motives. To conclude, consumers are increasingly interested in new coffee products. Understanding the functional and emotional factors of coffee consumption contributes to supporting new coffee product development and commercialisation
Fixação biológica de nitrogênio em soja sob déficit hídrico.
Avaliaram-se em condições controladas os efeitos do déficit hídrico sobre a fixação biológica do nitrogênio (FBN) e componentes de rendimento em plantas de soja (Glycine max (L.) Merrill) (cv. BRS-232 e BRS-268) em três experimentos e em três estádios reprodutivos, em que as plantas foram submetidas a duas disponibilidades hídricas: condição normal de capacidade de campo e de déficit hídrico nos estádios reprodutivos. Durante os estádios R2 e R3 foram avaliados a condutância estomática; a massa e o número de nódulos; e os teores de ureídeos (ácido alantóico e alantoína) na seiva do xilema; além do rendimento de sementes por planta em R8. O déficit hídrico reduziu os atributos relacionados à FBN, com reflexos na redução dos componentes de rendimento de grãos das plantas. A condição de déficit hídrico durante 13 dias entre as fases reprodutivas de florescimento pleno e formação inicial de vagens reduziu a massa e o número de nódulos em soja, com consequente redução média no rendimento de grãos de soja por planta em 14%
Biological nitrogen fixation in soybean under water restriction and exposed to 1-methylcyclopropene.
ABSTRACT: The objective of this work was to assess the effects of 1-methylcyclopropene (1-MCP) on traits related with biological nitrogen fixation on 'BRS 268' soybean (Glycine max) subjected to water restriction. Plants were either exposed to drought between 32 (R2) and 47 (R3) days after sowing (DAS) or kept well-watered, in combination with exposure or not to 1?MCP. On the second day under drought (34 DAS), plants from both water conditions were exposed to 1-MCP in a hermetically sealed chamber for 15 hours. Control plants, dry or well? watered, that were not exposed to 1?MCP were kept in a separate chamber. At 36 (R2) and 47 (R3) DAS, shoot and root dry weights, leaf area index, number and dry weight of nodules, total ureides in sap, and N concentration in leaves were assessed. From 47 DAS on, extra plants were well watered until physiological maturity (R 8) and assessed for yield components. Water restriction increased ureides in sap and reduced N in leaves in R2; reduced the number and mass of nodules, shoot dry weight, and leaf area index in R3; and reduced the number of pods and seed mass of plants not exposed to 1?MCP. However, when plants are exposed to 1-MCP, there is an attenuation of water restriction effects. CONTEÚDO: O objetivo deste trabalho foi avaliar os efeitos do 1?metilciclopropeno (1?MCP) em parâmetros relacionados à fixação biológica de nitrogênio em soja (Glycine max) 'BRS 268' submetida à restrição hídrica. As plantas foram submetidas à seca entre 32 (R2) e 47 (R3) dias após a semeadura (DAS) ou mantidas bem irrigadas, em combinação com exposição ou não ao 1?MCP. No segundo dia sob seca (34 DAS), as plantas de ambas as condições hídricas foram expostas ao 1?MCP em câmara hermeticamente fechada por 15 horas. As plantas?controle, sob restrição hídrica ou bem irrigadas, não expostas ao 1?MCP foram mantidas em câmara separada. Aos 36 (R2) e 47 (R3) DAS, foram avaliados massa seca da parte aérea e das raízes, índice de área foliar, número e massa seca de nódulos, ureídos totais na seiva e concentração de N foliar. A partir dos 47 DAS, as plantas remanescentes foram mantidas bem irrigadas até a maturação fisiológica (R8) e os componentes de produção foram avaliados. A restrição hídrica aumentou os ureídos na seiva e reduziu o N foliar em R2; reduziu o número e a massa de nódulos, a massa seca da parte aérea e o índice de área foliar em R3; e reduziu o número de vagens e a massa de sementes em plantas sem exposição ao 1?MCP. No entanto, quando as plantas são expostas ao 1?MCP, há atenuação do efeito da restrição hídrica
Community supported agriculture farmers' perceptions of management benefits and drawbacks
Community Supported Agriculture (CSA) is a direct partnership between producer(s) and
a group of consumers/members to share the risks and responsibilities of farming activities. CSA aims
at producing and providing environmentally, socially, economically, and nutritionally sustainable
food. Past research has focused on CSA members\u2019 motivations. This research aims to gain a better
understanding of CSA farmers\u2019 perceived benefits and drawbacks in managing a CSA farm, and
whether CSA management perception varies in dierent countries. The research collected data from
35 farmers that were based in the United States (US) and Hungary (HU). Data elaboration includes
a one-way Anova test, Chi-square test, principal component analysis, and multiple multivariate
linear regressions. The results support that US and HU farmers have similar positive perceptions
of CSA farming management, especially in food quality, nutritional value products, environmental,
and community benefits. The main dierences concentrate on economic, financial, and management
perceptions. CSA success as an alternative agro-food production and distribution system relies on
the capability to involve CSA members. Therefore, CSA farmers\u2019 management skills may evolve
to ensure the performance of communication and community engaging practices. The main CSA
concern is ensuring a fair income and living wage for the farmers and labor force. There is a need for
better balancing non-monetary and monetary benefits for the farmers
A device to characterize optical fibres
ATLAS is a general purpose experiment approved for the LHC collider at CERN.
An important component of the detector is the central hadronic calorimeter; for
its construction more than 600,000 Wave Length Shifting (WLS) fibres
(corresponding to a total length of 1,120 Km) have been used.
We have built and put into operation a dedicated instrument for the
measurement of light yield and attenuation length over groups of 20 fibres at a
time.
The overall accuracy achieved in the measurement of light yield
(attenuation length) is 1.5% (3%).
We also report the results obtained using this method in the quality control
of a large sample of fibres.Comment: 17 pages 20 figeres submitted to NIM journa
Prospective study of a molecular selection profile for RAS wild type colorectal cancer patients receiving irinotecan-cetuximab
Background: The aim of our study was to evaluate whether a panel of biomarkers, prospectively analysed might be able to predict patients' clinical outcome more accurately than RAS status alone. Methods: K-RAS (exons 2, 3, 4) wild type colorectal cancer patients, candidates to second/third-line cetuximab with chemotherapy were prospectively allocated into 2 groups on the basis of their profile: favourable (BRAF and PIK3CA exon 20 wild type, EGFR GCN ≥ 2.6, HER-3 Rajkumar score ≤ 8, IGF-1 immunostaining < 2) or unfavourable (any of the previous markers altered or mutated). After the introduction of N-RAS status (exons 2, 3, 4) only RAS wild type patients were considered eligible. Results: Forty-six patients were enrolled. Seventeen patients (37%) were allocated to the favourable and 29 patients (63%) to the unfavourable profile. RR in the favourable and unfavourable group was 11/17 (65%) and 2/29 (7%) (p = 0.007) respectively. The favourable group also showed an improved PFS (8months vs. 3months, p < 0.0001) and OS (15months vs. 6months, p < 0.0001). Conclusions: Our results suggest that prospective selection of optimal candidates for cetuximab treatment is feasible and may be able to improve clinical outcom
Thyroid nodules treated with percutaneous radiofrequency thermal ablation: a comparative study
Percutaneous radiofrequency thermal ablation (RTA) was reported as an effective tool for the management of thyroid nodules (TNs). The aim of this study was to investigate the effects of RTA and to establish whether they were treatment-related by comparison with a matched, untreated control group
Nanostructured zirconia-based ceramics and composites in dentistry: A state-of-the-art review
The objective of this paper is to review the current knowledge on the development of nanostructured zirconia-based ceramics and composites suitable for application in dentistry. Isi Web of Science, Science Direct, Scientific.net databases, and Google were searched electronically for the period of 1980 to the present, matching the keywords \u201cnano\u201d with the keywords: \u201cZirconia, ZrO2, Y-TZP, and dental, dentistry\u201d. A total of 74 papers were found, with the majority coming from Asia, indicating a more active scientific interest on the topic in this geographic area, followed by Europe, South America, and North America. The research shows, even though the scientific activity on nanostructured ceramics was intense in the last fifteen years, the development of fully dense zirconia-based nanoceramics is yet at an initial stage, most of all from the point of view of the clinical applications. It has been demonstrated that nanostructured ceramics can show improved properties because of the reduction of the grain size to the nanoscale. This is also true for zirconia-based nanoceramics, where some improvements in mechanical, optical, as well as resistance in low-temperature degradation have been observed. Potential applications of this class of material in the dental field are discussed, summarizing the results of the latest scientific research
Activation studies of the γ-carbonic anhydrases from the antarctic marine bacteria pseudoalteromonas haloplanktis and colwellia psychrerythraea with amino acids and amines
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