Unsupervised learning architecture based on neural Darwinism and Hopfield networks recognizes symbols with high accuracy

This paper introduces a novel unsupervised learning paradigm inspired by Gerald Edelman's theory of neuronal group selection ("Neural Darwinism"). The presented automaton learns to recognize arbitrary symbols (e.g., letters of an alphabet) when they are presented repeatedly, as they are when children learn to read. On a second hierarchical level, the model creates abstract categories representing the learnt symbols. The fundamental computational unit are simple McCulloch-Pitts neurons arranged into fully-connected groups (Hopfield networks with randomly initialized weights), which are "selected", in an evolutionary sense, through symbol presentation. The learning process is fully tractable and easily interpretable for humans, in contrast to most neural network architectures. Computational properties of Hopfield networks enabling pattern recognition are discussed. In simulations, the model achieves high accuracy in learning the letters of the Latin alphabet, presented as binary patterns on a grid. This paper is a proof of concept with no claims to state-of-the-art performance in letter recognition, but hopefully inspires new thinking in bio-inspired machine learning.Comment: 12 pages, 4 figure

LSTM model predicting outcome of strategic thinking task exhibits representations of level-k thinking

Which neural mechanisms underlie strategic thinking in the human brain? Neuroeconomic research has not yet bridged the gap between theoretical models of higher-order reasoning and the precise mechanisms implemented in neural networks in the human brain. In this paper, I demonstrate that a recurrent neural network model can learn to perform strongly in the simple strategic game Rock-Paper-Scissors. In doing so, it develops implicit representations of strategically important variables (the levels $k$ of reasoning) which economists have postulated in theoretical models. These representations can be extracted from the hidden activations of the neural network. These findings hint at a connection between the mechanisms implicit in recurrent neural networks and models of strategic thinking in economic theory. Future empirical brain research can investigate whether these mechanisms correspond to mechanisms implicit in biological neural networks.Comment: 11 pages, 5 figure

FGF Pyramus Has a Transmembrane Domain and Cell-Autonomous Function in Polarity

Most fibroblast growth factors (FGFs) function as receptor ligands through their conserved FGF domain, but sequences outside this domain vary and are not well studied. This core domain of 120 amino acids (aa) is flanked in all FGFs by highly divergent amino-terminal and carboxy-terminal sequences of variable length. Drosophila has fewer FGF genes, with only three identified to date, pyramus (pyr), thisbe (ths), and branchless (bnl), and all three encoding relatively large FGF proteins (∼80 kDa). We hypothesized that the longer FGF proteins present in Drosophila and other organisms may relate to an ancestral form, in which multiple functions or regulatory properties are present within a single polypeptide. Here, we focused analysis on Pyr, finding that it harbors a transmembrane domain (TMD) and extended C-terminal intracellular domain containing a degron. The intracellular portion limits Pyr levels, whereas the TMD promotes spatial precision in the paracrine activation of Heartless FGF receptor. Additionally, degron deletion mutants that upregulate Pyr exhibit cell polarity defects that lead to invagination defects at gastrulation, demonstrating a previously uncharacterized cell-autonomous role. In summary, our data show that Pyr is the first demonstrated transmembrane FGF, that it has both extracellular and intracellular functions, and that spatial distribution and levels of this particular FGF protein are tightly regulated. Our results suggest that other FGFs may be membrane tethered or multifunctional like Pyr

FGF Pyramus Has a Transmembrane Domain and Cell-Autonomous Function in Polarity

Most fibroblast growth factors (FGFs) function as receptor ligands through their conserved FGF domain, but sequences outside this domain vary and are not well studied. This core domain of 120 amino acids (aa) is flanked in all FGFs by highly divergent amino-terminal and carboxy-terminal sequences of variable length. Drosophila has fewer FGF genes, with only three identified to date, pyramus (pyr), thisbe (ths), and branchless (bnl), and all three encoding relatively large FGF proteins (∼80 kDa). We hypothesized that the longer FGF proteins present in Drosophila and other organisms may relate to an ancestral form, in which multiple functions or regulatory properties are present within a single polypeptide. Here, we focused analysis on Pyr, finding that it harbors a transmembrane domain (TMD) and extended C-terminal intracellular domain containing a degron. The intracellular portion limits Pyr levels, whereas the TMD promotes spatial precision in the paracrine activation of Heartless FGF receptor. Additionally, degron deletion mutants that upregulate Pyr exhibit cell polarity defects that lead to invagination defects at gastrulation, demonstrating a previously uncharacterized cell-autonomous role. In summary, our data show that Pyr is the first demonstrated transmembrane FGF, that it has both extracellular and intracellular functions, and that spatial distribution and levels of this particular FGF protein are tightly regulated. Our results suggest that other FGFs may be membrane tethered or multifunctional like Pyr

Consequences of "development" & globalization in Cape Verde

Die kapverdischen Inseln erleben seit den frühen 1990er Jahren einen enormen Wandel. Nach der Unabhängigkeit im Jahre 1975 gewann 1991 die konservative, mitte-rechts Partei MpD die ersten Mehrparteienwahlen und initiierte in der Folge einen Prozess marktorientierter Wirtschaftsreformen – vor allem in Form von massiven Privatisierungen – um Globalisierung als Lösung für die wirtschaftlichen Schwierigkeiten des Landes voranzutreiben. Diese neoliberalen Reformen wurden von der ehemaligen Unabhängikeitspartei PAICV, die im Jahr 2001 die Macht wiedererlangte, mehr oder weniger fortgesetzt. Die kapverdianische Wirtschaft ist stark abhängig von den Remittances, die von der großen Anzahl der in der Diaspora lebenden Emigranten geschickt werden, und von ausländischer Entwicklungszusammenarbeit. In den letzten Jahren erlebte das Land jedoch ein noch nie dagewesenes Wirtschaftswachstum. Dieser Aufschwung basiert vor allem auf der boomenden Tourismusindustrie und auf privaten Auslandsinvestitionen, insbesondere aus Portugal und Italien. Gleichzeitig haben die Remittances und die Entwicklungszusammenarbeit allerdings angefangen zu sinken. Im Jahr 2008 wurden die Kapverden zum Status eines MDC (Middle Development Country) “hochgestuft” und wird seither als “Afrikanische Erfolgsgeschichte” gepriesen. Diese rezente “Entwicklung” hat jedoch eine simplifizierte Definition von “Entwicklung” zur Grundlage, die im politischen und ökonomischen Diskurs weit verbreitet ist und “Entwicklung” nur im Sinne von Wirtschaftswachstum misst. Trotz des Wirtschaftsaufschwungs ist die Arbeitslosigkeit weiterhin relativ hoch, die Einkommensschere wächst, und es bilden sich zusehends neue urbane Armenviertel. Kapverdianische Marktfrauen (Rabidantes) – eine wichtige ökonomische, soziale, und generationsübergreifende Gruppe – verlieren aufgrund der jüngsten ausländischen Privatinvestitionen ihre Existenzgrundlage. Diese Vorgänge werden im Großen und Ganzen von der kapverdianischen Regierung ignoriert oder verschwiegen, da sie nicht in das Bild eines “modernen”, “entwickelten” Landes passen. “Kulturelle” oder “nationale” Identitätskonstruktion ist auf den Kapverden stark verankert in Diskussionen bezüglich der Nähe zu Afrika oder Europa. Die rassialisierten Wahrnehmungen von “Afrikanisch” bzw. “Europäisch” und die rassialisierte, gesellschaftliche Hierarchisierung bestehen teilweise bis heute fort und sind untrennbar voem historischen Kontext des Portugiesischen Kolonialismus und dessen rassistischen Klassifikationssystems. Im gegenwärtigen Kontext von “Entwicklung” und Globalisierung werden diese Vorstellungen von “Afrikanisch” und “Europäisch” weiters mit “unterentwickelt” und “entwickelt” assoziiert. In diesem Zusammenhang erleben viele kapverdianische Jugendliche eine Veränderung ihrer Möglichkeiten (beipielsweise die Verbreitung des Internets) ihre Identität entsprechend den allgemeinen Erwartungen bezüglich der für die Teilnahme an dieser “Entwicklung” notwendigen Eigenschaften “anzupassen”. Es wird somit argumentiert, dass die Klassifikationen von “Afrikanisch” und “Europäisch” – und folglich von Identitäten – heutzutage mit mehr oder weniger Chancen bzw. Möglichkeiten assoziiert werden. Dementsprechend sind diese Vorstellungen weiterhin rassialisiert und werden als relevant bzw. irrelevant für den persönlichen Aufstieg eines Menschen angesehen.The Cape Verde islands have been undergoing enormous transformation since the early 1990s. After independence in 1975, the conservative center-right MpD won the first multi-party elections in 1991 and subsequently initiated a process of market-oriented economic reforms, primarily in the form of massive privatizations, to promote globalization as a solution to the country’s economic difficulties. These neoliberal reforms were more or less continued by the former independence-party PAICV, which regained power in 2001. The Cape Verdean economy heavily depends on the remittances sent by the great number of emigrants living in the diaspora and on foreign development assistance. In recent years, however, the country experienced an unprecedented economic growth. This upswing is first and foremost based on the booming tourism industry and on private foreign investments, primarily from Portugal and Italy. At the same time, however, remittances and development assistance have started to decline. In 2008, Cape Verde was “upgraded” to the status of an MDC (Middle Development Country) and is since praised as the “African success story”. Yet, this recent “development” is based on a simplified definition of “development” used in the common political and economic discourse, which measures “development” only in terms of economic growth. In spite of the economic upturn, the unemployment rate remains relatively high, the income gap is increasing, and new urban slums are forming rapidly. Cape Verdean market women (Rabidantes), an important economic, social, and generational group, are losing their basis of existence due to recent private foreign investments. These instances are generally ignored or concealed by the Cape Verdean government as they do not fit into the picture of a “modern”, “developed” country. In Cape Verde, “cultural” or “national” identity construction has been firmly established in discussions regarding the closeness to Africa or Europe. The racialized perceptions of “African” and “European”, respectively, and the racialized, societal hierarchization have partly continued up until the present and are not separable from the historical context of Portuguese colonialism and its racist system of classification. In the contemporary context of “development” and globalization, these notions of “African” and “European” are further associated with “undeveloped” and “developed”. In this regard, many Cape Verdean adolescents are experiencing a modification of their opportunities (i.e. the dissemination of the Internet) to “adapt” their identity in accordance with the general expectations concerning the necessary attributes to partake in this “development”. It is therefore argued that the classifications of “African” and “European” – and thus of identities – today are associated with more or less chances and opportunities, respectively. Consequently, these notions are still racialized and considered relevant and irrelevant, respectively, to a person’s personal advancement

Lipid-induced changes in the secondary structure of snake venom cardiotoxins.

The secondary structures of three snake venom cardiotoxins (from Hemachatus hemachatus, Naja naja atra, and Naja naja naja), in aqueous solution and in a lipid-bound form, were investigated by Fourier-transform infrared spectroscopy. The conformation-sensitive protein infrared bands in the amide I region were analyzed using deconvolution and band-fitting procedures. The spectra of the three cardiotoxins in aqueous buffer are very similar; they indicate a high content of both antiparallel beta-sheet structure and unordered conformation. Moreover, component bands characteristic of turns can also be identified. The binding of cardiotoxins to bilayers of dimyristoylphosphatidyl-glycerol results in an increased content of a beta-structure at the expense of the nonordered conformation. It is suggested that lipid-induced conformational transitions to a beta-structure, similar to that observed with cardiotoxins, may be operative also in membrane interaction of other proteins and peptides, particularly with those which have a small tendency to form alpha-helices

The migrations of Drosophila muscle founders and primordial germ cells are interdependent

Caudal visceral mesoderm (CVM) cells migrate from posterior to anterior of the Drosophila embryo as two bilateral streams of cells to support the specification of longitudinal muscles along the midgut. To accomplish this long-distance migration, CVM cells receive input from their environment, but little is known about how this collective cell migration is regulated. In a screen we found that wunen mutants exhibit CVM cell migration defects. Wunens are lipid phosphate phosphatases known to regulate the directional migration of primordial germ cells (PGCs). PGC and CVM cell types interact while PGCs are en route to the somatic gonadal mesoderm, and previous studies have shown that CVM impacts PGC migration. In turn, we found here that CVM cells exhibit an affinity for PGCs, localizing to the position of PGCs whether mislocalized or trapped in the endoderm. In the absence of PGCs, CVM cells exhibit subtle changes, including more cohesive movement of the migrating collective, and an increased number of longitudinal muscles is found at anterior sections of the larval midgut. These data demonstrate that PGC and CVM cell migrations are interdependent and suggest that distinct migrating cell types can coordinately influence each other to promote effective cell migration during development

Entropy and Information Causality in General Probabilistic Theories

We investigate the concept of entropy in probabilistic theories more general than quantum mechanics, with particular reference to the notion of information causality (IC) recently proposed by Pawlowski et al (2009 arXiv:0905.2292). We consider two entropic quantities, which we term measurement and mixing entropy. In the context of classical and quantum theory, these coincide, being given by the Shannon and von Neumann entropies, respectively; in general, however, they are very different. In particular, while measurement entropy is easily seen to be concave, mixing entropy need not be. In fact, as we show, mixing entropy is not concave whenever the state space is a non-simplicial polytope. Thus, the condition that measurement and mixing entropies coincide is a strong constraint on possible theories. We call theories with this property monoentropic. Measurement entropy is subadditive, but not in general strongly subadditive. Equivalently, if we define the mutual information between two systems A and B by the usual formula I (A : B) = H(A) + H(B)− H(AB), where H denotes the measurement entropy and AB is a non-signaling composite of A and B, then it can happen that I (A : BC) \u3c I (A : B). This is relevant to IC in the sense of Pawlowski et al: we show that any monoentropic non-signaling theory in which measurement entropy is strongly subadditive, and also satisfies a version of the Holevo bound, is informationally causal, and on the other hand we observe that Popescu–Rohrlich boxes, which violate IC, also violate strong subadditivity. We also explore the interplay between measurement and mixing entropy and various natural conditions on theories that arise in quantum axiomatics

The migrations of Drosophila muscle founders and primordial germ cells are interdependent

Caudal visceral mesoderm (CVM) cells migrate from posterior to anterior of the Drosophila embryo as two bilateral streams of cells to support the specification of longitudinal muscles along the midgut. To accomplish this long-distance migration, CVM cells receive input from their environment, but little is known about how this collective cell migration is regulated. In a screen we found that wunen mutants exhibit CVM cell migration defects. Wunens are lipid phosphate phosphatases known to regulate the directional migration of primordial germ cells (PGCs). PGC and CVM cell types interact while PGCs are en route to the somatic gonadal mesoderm, and previous studies have shown that CVM impacts PGC migration. In turn, we found here that CVM cells exhibit an affinity for PGCs, localizing to the position of PGCs whether mislocalized or trapped in the endoderm. In the absence of PGCs, CVM cells exhibit subtle changes, including more cohesive movement of the migrating collective, and an increased number of longitudinal muscles is found at anterior sections of the larval midgut. These data demonstrate that PGC and CVM cell migrations are interdependent and suggest that distinct migrating cell types can coordinately influence each other to promote effective cell migration during development

Irradiation for mold and mycotoxin control : a review

The mycotoxin issue requires constant vigilance from economic, regulatory, and scientific agents to minimize its toxicological effects on human and on animals. The implementation of good practices to avoid fungal growth and mycotoxin production on agricultural commodities is essential to achieve most restrictive safety standards; however, the contribution of novel technologies that may act on post-harvesting and post-storage situations may be equally important. Several methodologies, more or less technologically advanced, may be used for this purpose. In this work, we review the role, contribution, and impact of irradiation technology to control the presence of fungi and mycotoxins in food and in feed. The effect of this technology on the viability of mold spores and on the elimination of mycotoxins is reviewed. A critical evaluation of the advantages and disadvantages of irradiation in this context is presented.Thalita Calado and Luis Abrunhosa received support through grants SFRH/BD/79364/2011 and SFRH/BPD/43922/2008, respectively, from the Fundacao para a Ciencia e Tecnologia - FCT, Portugal. The authors also thank the FCT Strategic Project PEst-OE/EQB/LA0023/2013 and the project "BioInd - Biotechnology and Bioengineering for Improved Industrial and Agro-Food processes, REF. NORTE-07-0124-FEDER-000028," which is cofunded by the Programa Operacional Regional do Norte (ON. 2 - O Novo Norte), QREN, FEDER