The meaning of natural selection revisited at the molecular level

Various molecular interaction mechanisms cause biased transmission of genes. Meiotic drive is an example of strong bias, and compartmentalization of mammalian chromosomes reflects weak bias. Such biases are the results of interaction between DNA and proteins, and should be distinguished from natural selection. Separating the effects of molecular interaction from those of natural selection, however, is often very difficult. Natural selection and molecular mechanisms interact, and our understanding of how selection works requires revision.     

Interactive language learning by robots: the transition from babbling to word forms

The advent of humanoid robots has enabled a new approach to investigating the acquisition of language, and we report on the development of robots able to acquire rudimentary linguistic skills. Our work focuses on early stages analogous to some characteristics of a human child of about 6 to 14 months, the transition from babbling to first word forms. We investigate one mechanism among many that may contribute to this process, a key factor being the sensitivity of learners to the statistical distribution of linguistic elements. As well as being necessary for learning word meanings, the acquisition of anchor word forms facilitates the segmentation of an acoustic stream through other mechanisms. In our experiments some salient one-syllable word forms are learnt by a humanoid robot in real-time interactions with naive participants. Words emerge from random syllabic babble through a learning process based on a dialogue between the robot and the human participant, whose speech is perceived by the robot as a stream of phonemes. Numerous ways of representing the speech as syllabic segments are possible. Furthermore, the pronunciation of many words in spontaneous speech is variable. However, in line with research elsewhere, we observe that salient content words are more likely than function words to have consistent canonical representations; thus their relative frequency increases, as does their influence on the learner. Variable pronunciation may contribute to early word form acquisition. The importance of contingent interaction in real-time between teacher and learner is reflected by a reinforcement process, with variable success. The examination of individual cases may be more informative than group results. Nevertheless, word forms are usually produced by the robot after a few minutes of dialogue, employing a simple, real-time, frequency dependent mechanism. This work shows the potential of human-robot interaction systems in studies of the dynamics of early language acquisition.     

Learning a functional grammar of protein domains using natural language word embedding techniques

In this paper, using Word2vec, a widely-used natural language processing method, we demonstrate that protein domains may have a learnable implicit semantic “meaning” in the context of their functional contributions to the multi-domain proteins in which they are found. Word2vec is a group of models which can be used to produce semantically meaningful embeddings of words or tokens in a fixed-dimension vector space. In this work, we treat multi-domain proteins as “sentences” where domain identifiers are tokens which may be considered as “words.” Using all InterPro (Finn et al. 2017) pfam domain assignments we observe that the embedding could be used to suggest putative GO assignments for Pfam (Finn et al. 2016) domains of unknown function.     

A word of a natural language has 2.718 different meanings or slightly more

The capacity of lexical decision-making in the brain conforms to the indefiniteness latent in natural languages. The average number of different meanings per word of a natural language is measured to be 2.805 +/- 0.005 irrespective of whether the language is Chinese, English or Japanese. If one can almost perfectly comprehend words and sentences written in a natural language in a context-dependent manner, the average number of different meanings per word would reduce to e (= 2.718281828459...), the base of natural or Napierian logarithms.     

D-serine: a new word in the glutamatergic neuro-glial language

Summary. Gliotransmission is a process in which astrocytes are dynamic elements that influence synaptic transmission and synaptogenesis. The best-known gliotransmitters are glutamate and ATP. However, in the past decade, it has been demonstrated that D-serine, a D-amino acid, acts as a gliotransmitter in glutamatergic synapses. The physiological relevance of D-serine is sustained by the way in which it modulates the action of glutamatergic neurotransmission, neuronal migration and long-term potentiation (LTP). In addition, the synthesis and degradation mechanisms of D-serine have been proposed as potential therapeutic targets for the treatment of Alzheimer’s disease, schizophrenia and related disorders. In the present review, detailed information is provided about the physiological and physiopathological relevance of D-serine, including metabolic and regulation aspects.     

Detecting meaning in dream reports: An extension of a word search approach.

Building on previous investigations of waking–dreaming continuities using word search technology (Bulkeley 2009a, 2009b; Domhoff & Schneider, 2008), we demonstrate that a blind analysis of a dream series using only word search methods can accurately predict many important aspects of the individual's waking life, including personality attributes, relationships, activities, and cultural preferences. Results from a study of the “Van” dream series (N = 192) show that blind inferences drawn from a word search analysis were almost entirely accurate according to the dreamer. After presenting these findings we discuss several remaining shortcomings and suggest ways of improving the method for use by other researchers involved in the search for a more systematic understanding of meaning in dreams. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unstable Escherichia coli L forms revisited: growth requires peptidoglycan synthesis

Growing bacterial L forms are reputed to lack peptidoglycan, although cell division is normally inseparable from septal peptidoglycan synthesis. To explore which cell division functions L forms use, we established a protocol for quantitatively converting a culture of a wild-type Escherichia coli K-12 strain overnight to a growing L-form-like state by use of the beta-lactam cefsulodin, a specific inhibitor of penicillin-binding proteins (PBPs) 1A and 1B. In rich hypertonic medium containing cefsulodin, all cells are spherical and osmosensitive, like classical L forms. Surprisingly, however, mutant studies showed that colony formation requires d-glutamate, diaminopimelate, and MurA activity, all of which are specific to peptidoglycan synthesis. High-performance liquid chromatography analysis confirmed that these L-form-like cells contain peptidoglycan, with 7% of the normal amount. Moreover, the beta-lactam piperacillin, a specific inhibitor of the cell division protein PBP 3, rapidly blocks the cell division of these L-form-like cells. Similarly, penicillin-induced L-form-like cells, which grow only within the agar layers of rich hypertonic plates, also require d-glutamate, diaminopimelate, and MurA activity. These results strongly suggest that cefsulodin- and penicillin-induced L-form-like cells of E. coli-and possibly all L forms-have residual peptidoglycan synthesis which is essential for their growth, probably being required for cell division.     

From survivors to replicators: evolution by natural selection revisited

For evolution by natural selection to occur it is classically admitted that the three ingredients of variation, difference in fitness and heredity are necessary and sufficient. In this paper, I show using simple individual-based models, that evolution by natural selection can occur in populations of entities in which neither heredity nor reproduction are present. Furthermore, I demonstrate by complexifying these models that both reproduction and heredity are predictable Darwinian products (i.e. complex adaptations) of populations initially lacking these two properties but in which new variation is introduced via mutations. Later on, I show that replicators are not necessary for evolution by natural selection, but rather the ultimate product of such processes of adaptation. Finally, I assess the value of these models in three relevant domains for Darwinian evolution.     

Our friends in nature: Class and animal symbolism

The paper approaches Dumont's hypothesis of value hierarchy by examining the interconnection between gender, kinship and seniority in Malay rural society, maintaining the idea that seniority is a prominent value. A process is described in which a structure of gender‐neutral seniority and balanced gender collectivities gives way to a stronger collusion between seniority and maleness, personified in the husband‐wife dyad. The author is open to the possibility of a “hierarchising impulse” in cultural processes, but doubts that ultimate values will ever fully emerge in social realities because “society” has no unambiguous delimitation, and because organizational and communicative domains shrink and expand over time so that any dominant value can be challenged through organizational innovations.     

Event-related brain potentials when conjugating Russian verbs: The modularity of language procedures

Within the alternative concepts of “two-system” and “single-system” language models, brain mechanisms for the generation of regular and irregular forms of Russian verbs have been studied. The evoked EEG activity was recorded in 19 channels with random alternation of different speech-morphology operations. The infinitives of imperfective verbs that belong either to the productive group (conventionally, the default, or regular, class) or to the unproductive group (conventionally, the irregular class) were presented to healthy subjects. The subjects were to produce the first-person present-time forms of these verbs. The results of the analysis of the event-related potentials (ERPs) of 22 subjects are presented. Statistically valid ERP amplitude distinctions between the verb groups are found only in latencies of 600–850 ms in the central and parietal zones of the cortex. The peak values of the irregular-verb potentials are negative in this region in relation to the peak values of the regular-verb potentials. The findings are interpreted as the effect of various complexities of mental work with verbs of different groups and do not support the hypothesis of the universality of the two-system brain mechanism for processing regular and irregular language phenomena.     

Problems with tense marking in children with specific language impairment: not how but when

Many children with specific language impairment (SLI) have persisting problems in the correct use of verb tense, but there has been disagreement as to the underlying reason. When we take into account studies using receptive as well as expressive language tasks, the data suggest that the difficulty for children with SLI is in knowing when to inflect verbs for tense, rather than how to do so. This is perhaps not surprising when we consider that tense does not have a transparent semantic interpretation, but depends on complex relationships between inflections and hierarchically organized clauses. An explanation in terms of syntactic limitations contrasts with a popular morpho-phonological account, the Words and Rules model. This model, which attributes problems to difficulties with applying a rule to generate regular inflected forms, has been widely applied to adult-acquired disorders. There are striking similarities in the pattern of errors in adults with anterior aphasia and children with SLI, suggesting that impairments in appreciation of when to mark tense may apply to acquired as well as developmental disorders.     

Availability of dicalcium phosphate to plants,when applied in various forms

Summary The availability of dicalcium phosphate in powder and granulated form mixed with ammonium sulfate, was tested in a greenhouse experiment. Two soils were used in the experiment: one from Rehovot, neutral and non calcareous, and the other from Gilat, slightly alkaline and calcareous. Clover (two cuttings) was the first crop and cow peas and corn succeeded. The yield results were fitted to Mitscherlich curves. In general, the results of greenhouse and laboratory experiments showed, that in both soils the dicalcium phosphate had approximately the same efficiency as phosphate fertilizer, as did superphosphate. It appears that additions of ammonium sulfate had no appreciable effect on phosphate availability. However, the granulation process lowered its solubility. It may be concluded that there is a possibility that citrate-soluble phosphate could be efficient on calcareous soils no less than the water-soluble form.This research work was financially supported by Fertilizers and Chemicals Ltd., Haifa, Israel.     

Progressive loss of access to spoken word forms in a case of Alzheimer's disease.

We report the results of a longitudinal study of a progressive anomia in a patient with dementia of the Alzheimer type (DAT). The anomia cannot be attributed to a deficit within the semantic system, but appears instead to arise from impaired access to the phonological lexicon at a post-semantic stage of the naming process: a deficit that hitherto has not been reported in DAT. Specific naming responses were affected consistently by the disorder, showing that disorders of access are not invariably associated with inconsistent responding. Before specific responses disappeared from spontaneous use, there appeared to be an intervening stage at which some responses could be elicited by an initial phoneme cue, suggesting a low level of spontaneous activity of insufficient strength to elicit a response unaided. The frequency of the name affected naming performance, but did not appear to interact with the severity of the naming disorder, suggesting that the parameters of the normal naming system were unaffected. It is claimed that important new insights into the characteristics of progressive anomia have been obtained by taking a longitudinal approach.     

A psycholinguistic model of natural language parsing implemented in simulated neurons

A natural language parser implemented entirely in simulated neurons is described. It produces a semantic representation based on frames. It parses solely using simulated fatiguing Leaky Integrate and Fire neurons, that are a relatively accurate biological model that is simulated efficiently. The model works on discrete cycles that simulate 10 ms of biological time, so the parser has a simple mapping to psychological parsing time. Comparisons to human parsing studies show that the parser closely approximates this data. The parser makes use of Cell Assemblies and the semantics of lexical items is represented by overlapping hierarchical Cell Assemblies so that semantically related items share neurons. This semantic encoding is used to resolve prepositional phrase attachment ambiguities encountered during parsing. Consequently, the parser provides a neurally-based cognitive model of parsing.