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81.
Cognitive Science is a promising field of research that deals with one of the most fundamental questions ever: how do beings know? However, despite the long and extensive tradition of the field it has not yet become an area of knowledge with scientific identity. This is primarily due to three reasons: the lack of boundaries in defining the object of study, i.e. cognition, the lack of a precise, robust and consistent scientific methodology and results, and the inner problems derived from its interdisciplinary nature. This paper presents a background review, a theoretical frame and a humble reflection on these topics in order to arouse the internal debate among readers once more.  相似文献   
82.
The comparison of related genomes has emerged as a powerful lens for genome interpretation. Here we report the sequencing and comparative analysis of 29 eutherian genomes. We confirm that at least 5.5% of the human genome has undergone purifying selection, and locate constrained elements covering ~4.2% of the genome. We use evolutionary signatures and comparisons with experimental data sets to suggest candidate functions for ~60% of constrained bases. These elements reveal a small number of new coding exons, candidate stop codon readthrough events and over 10,000 regions of overlapping synonymous constraint within protein-coding exons. We find 220 candidate RNA structural families, and nearly a million elements overlapping potential promoter, enhancer and insulator regions. We report specific amino acid residues that have undergone positive selection, 280,000 non-coding elements exapted from mobile elements and more than 1,000 primate- and human-accelerated elements. Overlap with disease-associated variants indicates that our findings will be relevant for studies of human biology, health and disease.  相似文献   
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85.
We consider a continuous review perishable (s,S) inventory system with a service facility consisting of a waiting hall of finite capacity and a single server. We assume two types of customers, ordinary and negative, arrive according to a Markovian Arrival Process (MAP). An ordinary customer joins the queue and a negative customer instead of joining the queue removes one ordinary customer from the queue. The removal rule adopted in this paper is RCE (removal of a customer from the end). The individual customer's unit demand is satisfied after a random time of service which is assumed to have a phase-type distribution. The life time of each item and the lead time of the reorders have been assumed to be independent exponential distributions. The joint probability distribution of the number of customers in the system and the inventory level is obtained for the steady state case. Various stationary system performance measures are computed and the total expected cost rate is calculated. The results are illustrated numerically.  相似文献   
86.
Abstract Scoring in a basketball game is a highly dynamic, non-linear process. NBA teams try to be more and more competitive each season. For instance, they incorporate into their rosters the best players in the world. This and other mechanisms concur to make the scoring process in NBA games exciting and rarely predictable. This paper is to study the behavior of timing and scoring in basketball games. The authors analyze all the games in five NBA regular seasons (2005–06, 2006–07, 2007–08, 2008–09, 2009–10), for a total of 6150 games. Scoring does not behave uniformly; therefore, the authors also analyze the distributions of the differences in points in the basketball games. To further analyze the behavior of the tail of the distribution, the authors also carry out a semilog-plot and a log-log plot to verify whether this trend approaches a Poisson distribution or a PL. This paper reveals different areas of behavior related to the score, with specific instances of time that could be considered tipping points of the game. The presence of these critical points suggests that there are phase transitions where the dynamic scoring of the games varies significantly.  相似文献   
87.
This article describes the acceptance and development of multi-modal systems thinking in Argentina in the last 5 years, both in theory and in practice. On the theoretical side, we show the efforts made to provide compatible epistemological doctrines for different modalities, starting with ethics and aesthetics. This took place first through the phenomenology of values and more recently in the context of Christian existentialism and continuing later on with the study of the relationship among other modalities. On the practical side, we describe the applications of this framework to study the so-called “crisis of the Argentine countryside”. This is a conflict between the community of farmers, the national government and the present situation with cattle producers. Other applications include a programme to teach action-research and projects related to abandoned children and education in indigenous communities.  相似文献   
88.
M Endres  T Fukuhara  D Pekker  M Cheneau  P Schauss  C Gross  E Demler  S Kuhr  I Bloch 《Nature》2012,487(7408):454-458
Spontaneous symmetry breaking plays a key role in our understanding of nature. In relativistic quantum field theory, a broken continuous symmetry leads to the emergence of two types of fundamental excitation: massless Nambu-Goldstone modes and a massive 'Higgs' amplitude mode. An excitation of Higgs type is of crucial importance in the standard model of elementary particle physics, and also appears as a fundamental collective mode in quantum many-body systems. Whether such a mode exists in low-dimensional systems as a resonance-like feature, or whether it becomes overdamped through coupling to Nambu-Goldstone modes, has been a subject of debate. Here we experimentally find and study a Higgs mode in a two-dimensional neutral superfluid close to a quantum phase transition to a Mott insulating phase. We unambiguously identify the mode by observing the expected reduction in frequency of the onset of spectral response when approaching the transition point. In this regime, our system is described by an effective relativistic field theory with a two-component quantum field, which constitutes a minimal model for spontaneous breaking of a continuous symmetry. Additionally, all microscopic parameters of our system are known from first principles and the resolution of our measurement allows us to detect excited states of the many-body system at the level of individual quasiparticles. This allows for an in-depth study of Higgs excitations that also addresses the consequences of the reduced dimensionality and confinement of the system. Our work constitutes a step towards exploring emergent relativistic models with ultracold atomic gases.  相似文献   
89.
Yuan P  Leonetti MD  Hsiung Y  MacKinnon R 《Nature》2012,481(7379):94-97
High-conductance voltage- and Ca(2+)-activated K(+) channels function in many physiological processes that link cell membrane voltage and intracellular Ca(2+) concentration, including neuronal electrical activity, skeletal and smooth muscle contraction, and hair cell tuning. Like other voltage-dependent K(+) channels, Ca(2+)-activated K(+) channels open when the cell membrane depolarizes, but in contrast to other voltage-dependent K(+) channels, they also open when intracellular Ca(2+) concentrations rise. Channel opening by Ca(2+) is made possible by a structure called the gating ring, which is located in the cytoplasm. Recent structural studies have defined the Ca(2+)-free, closed, conformation of the gating ring, but the Ca(2+)-bound, open, conformation is not yet known. Here we present the Ca(2+)-bound conformation of the gating ring. This structure shows how one layer of the gating ring, in response to the binding of Ca(2+), opens like the petals of a flower. The degree to which it opens explains how Ca(2+) binding can open the transmembrane pore. These findings present a molecular basis for Ca(2+) activation of K(+) channels and suggest new possibilities for targeting the gating ring to treat conditions such as asthma and hypertension.  相似文献   
90.
Chromosome 18 appears to have the lowest gene density of any human chromosome and is one of only three chromosomes for which trisomic individuals survive to term. There are also a number of genetic disorders stemming from chromosome 18 trisomy and aneuploidy. Here we report the finished sequence and gene annotation of human chromosome 18, which will allow a better understanding of the normal and disease biology of this chromosome. Despite the low density of protein-coding genes on chromosome 18, we find that the proportion of non-protein-coding sequences evolutionarily conserved among mammals is close to the genome-wide average. Extending this analysis to the entire human genome, we find that the density of conserved non-protein-coding sequences is largely uncorrelated with gene density. This has important implications for the nature and roles of non-protein-coding sequence elements.  相似文献   
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