804 research outputs found
Three-point correlators for giant magnons
Three-point correlation functions in the strong-coupling regime of the
AdS/CFT correspondence can be analyzed within a semiclassical approximation
when two of the vertex operators correspond to heavy string states having large
quantum numbers while the third vertex corresponds to a light state with fixed
charges. We consider the case where the heavy string states are chosen to be
giant magnon solitons with either a single or two different angular momenta,
for various different choices of light string states.Comment: 15 pages. Latex. v2: Misprints corrected. Published versio
Signatures of arithmetic simplicity in metabolic network architecture
Metabolic networks perform some of the most fundamental functions in living
cells, including energy transduction and building block biosynthesis. While
these are the best characterized networks in living systems, understanding
their evolutionary history and complex wiring constitutes one of the most
fascinating open questions in biology, intimately related to the enigma of
life's origin itself. Is the evolution of metabolism subject to general
principles, beyond the unpredictable accumulation of multiple historical
accidents? Here we search for such principles by applying to an artificial
chemical universe some of the methodologies developed for the study of genome
scale models of cellular metabolism. In particular, we use metabolic flux
constraint-based models to exhaustively search for artificial chemistry
pathways that can optimally perform an array of elementary metabolic functions.
Despite the simplicity of the model employed, we find that the ensuing pathways
display a surprisingly rich set of properties, including the existence of
autocatalytic cycles and hierarchical modules, the appearance of universally
preferable metabolites and reactions, and a logarithmic trend of pathway length
as a function of input/output molecule size. Some of these properties can be
derived analytically, borrowing methods previously used in cryptography. In
addition, by mapping biochemical networks onto a simplified carbon atom
reaction backbone, we find that several of the properties predicted by the
artificial chemistry model hold for real metabolic networks. These findings
suggest that optimality principles and arithmetic simplicity might lie beneath
some aspects of biochemical complexity
Recommended from our members
Closed Strings and Moduli in AdS3/CFT2
String theory on AdS3ĂS3ĂT4 has 20 moduli. We investigate how the perturbative closed string spectrum changes as we move around this moduli space in both the RR and NSNS flux backgrounds. We find that, at weak string coupling, only four of the moduli affect the energies. In the RR background the only effect of these moduli is to change the radius of curvature of the background. On the other hand, in the NSNS background, the moduli introduce worldsheet interactions which enable the use of integrability methods to solve the spectral problem. Our results show that the worldsheet theory is integrable across the 20 dimensional moduli space
Exploring Relationship between Perception Indicators and Mitigation Behaviors of Soil Erosion in Undergraduate Students in Sonora, Mexico
Soil erosion represents a critical socio-economic and environmental hazard for Mexico and the world. Given that soil erosion is a phenomenon influenced by human activities, it is essential to know the level of cultural perspectives on this matter. An instrument with eight scales was applied to 275 university students from a northwestern Mexican city, which measured the knowledge about soil erosion, self-efficacy in solving the problem, future perspectives, perceived consequences, obstacles to addressing soil erosion, and mitigation intentions and behaviors. To analyze the relationship between the scales and the intentions and behaviors of soil erosion mitigation, a model of structural equations was tested. In summary, the participants know the problem of soil erosion, its impacts, and recognize risks to human and environmental health. They also know their important role within soil conservation; however, they identified significant obstacles to action. This study determined that each indicator has a correlation with soil erosion mitigation intentions except for the obstacles. The indicators that had the greatest positive relationship in mitigation intentions were knowledge, self-efficacy, and the perspective of the future. The implications of these results open the landscape to the creation of efficient strategies to mitigate soil erosion in this region and Mexico.</jats:p
Screening of native yeast from Agave duranguensis fermentation for isoamyl acetate production
Observation of associated near-side and away-side long-range correlations in âsNN=5.02ââTeV proton-lead collisions with the ATLAS detector
Two-particle correlations in relative azimuthal angle (ÎÏ) and pseudorapidity (Îη) are measured in âsNN=5.02ââTeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1ââÎŒb-1 of data as a function of transverse momentum (pT) and the transverse energy (ÎŁETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Îη|<5) ânear-sideâ (ÎÏâŒ0) correlation that grows rapidly with increasing ÎŁETPb. A long-range âaway-sideâ (ÎÏâŒÏ) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ÎŁETPb, is found to match the near-side correlation in magnitude, shape (in Îη and ÎÏ) and ÎŁETPb dependence. The resultant ÎÏ correlation is approximately symmetric about Ï/2, and is consistent with a dominant cosâĄ2ÎÏ modulation for all ÎŁETPb ranges and particle pT
Affective recognition from EEG signals: an integrated data-mining approach
Emotions play an important role in human communication, interaction, and decision making processes. Therefore, considerable efforts have been made towards the automatic identification of human emotions, in particular electroencephalogram (EEG) signals and Data Mining (DM) techniques have been then used to create models recognizing the affective states of users. However, most previous works have used clinical grade EEG systems with at least 32 electrodes. These systems are expensive and cumbersome, and therefore unsuitable for usage during normal daily activities. Smaller EEG headsets such as the Emotiv are now available and can be used during daily activities. This paper investigates the accuracy and applicability of previous affective recognition methods on data collected with an Emotiv headset while participants used a personal computer to fulfill several tasks. Several features were extracted from four channels only (AF3, AF4, F3 and F4 in accordance with the 10â20 system). Both Support Vector Machine and NaĂŻve Bayes were used for emotion classification. Results demonstrate that such methods can be used to accurately detect emotions using a small EEG headset during a normal daily activity
- âŠ