Massachusetts Institute of Technology

About: Massachusetts Institute of Technology is a education organization based out in Cambridge, Massachusetts, United States. It is known for research contribution in the topics: Population & Laser. The organization has 116795 authors who have published 268000 publications receiving 18272025 citations. The organization is also known as: MIT & M.I.T..

Learnability and cognition: The acquisition of argument structure.

Abstract: Part 1 A learnability paradox: argument structure and the lexicon the logical problem of language acquisition Baker's paradox attempted solutions to Baker's paradox. Part 2 Constraints on lexical rules: morphological and phonological constraints semantic constraints how semantic and morphological constraints might resolve Baker's paradox evidence for criteria-governed productivity problems for the criteria-governed productivity theory. Part 3 Constraints and the nature of argument structure: overview - why lexical rules carry semantic constraints constraints of lexical rules as manifestations of more general phenomena a theory of argument structure on universality. Part 4 Possible and actual forms: the problem of negative exceptions transitive action verbs as evidence for narrow subclasses the nature of narrow conflation classes defining and motivating subclasses of verbs licensing the four alterations the relation between narrow-range and broad-range rules. Part 5 Representation: the need for a theory of lexicosemantic representation is a theory of lexical semantics feasible? evidence for a semantic subsystem underlying verb meanings a cross-linguistic inventory of components of verb meaning a theory of the representation of grammatically relevant semantic structures explicit representations of lexical rules an lexicosemantic structures summary. Part 6 Learning: linking rules lexical semantic structures broad conflation classes (thematic cores) and broad range lexical rules summary of learning mechanisms. Part 7 Development: developmental sequence for argument structure alterations the unlearning problem children's argument structure changing rules are always semantically conditioned do children's errors have the same cause as adults? acquisition of verb meaning and errors in argument structure some predictions about the acquisition of narrow-range rules summary of development. Part 8 Conclusions: a brief summary of the resolution of the paradox argument structure as a pointer between syntactic structure and propositions the autonomy of semantic representation implications for the semantic bootstrapping hyposthesis conservatism, listedness and the lexicon spatial schemas and abstract thought.

Technical Change, Inequality, and the Labor Market

Abstract: This essay discusses the effect of technical change on wage inequality. I argue that the behavior of wages and returns to schooling indicates that technical change has been skill-biased during the past sixty years. Furthermore, the recent increase in inequality is most likely due to an acceleration in skill bias. In contrast to twentieth-century developments, much of the technical change during the early nineteenth century appears to be skill-replacing. I suggest that this is because the increased supply of unskilled workers in the English cities made the introduction of these technologies profitable. On the other hand, the twentieth century has been characterized by skill-biased technical change because the rapid increase in the supply of skilled workers has induced the development of skillcomplementary technologies. The recent acceleration in skill bias is in turn likely to have been a response to the acceleration in the supply of skills during the past several decades.

Insights into social insects from the genome of the honeybee Apis mellifera

Abstract: Here we report the genome sequence of the honeybee Apis mellifera, a key model for social behaviour and essential to global ecology through pollination. Compared with other sequenced insect genomes, the A. mellifera genome has high A+T and CpG contents, lacks major transposon families, evolves more slowly, and is more similar to vertebrates for circadian rhythm, RNA interference and DNA methylation genes, among others. Furthermore, A. mellifera has fewer genes for innate immunity, detoxification enzymes, cuticle-forming proteins and gustatory receptors, more genes for odorant receptors, and novel genes for nectar and pollen utilization, consistent with its ecology and social organization. Compared to Drosophila, genes in early developmental pathways differ in Apis, whereas similarities exist for functions that differ markedly, such as sex determination, brain function and behaviour. Population genetics suggests a novel African origin for the species A. mellifera and insights into whether Africanized bees spread throughout the New World via hybridization or displacement.

EMT, CSCs, and drug resistance: the mechanistic link and clinical implications

Abstract: The success of anticancer therapy is usually limited by the development of drug resistance. Such acquired resistance is driven, in part, by intratumoural heterogeneity - that is, the phenotypic diversity of cancer cells co-inhabiting a single tumour mass. The introduction of the cancer stem cell (CSC) concept, which posits the presence of minor subpopulations of CSCs that are uniquely capable of seeding new tumours, has provided a framework for understanding one dimension of intratumoural heterogeneity. This concept, taken together with the identification of the epithelial-to-mesenchymal transition (EMT) programme as a critical regulator of the CSC phenotype, offers an opportunity to investigate the nature of intratumoural heterogeneity and a possible mechanistic basis for anticancer drug resistance. In fact, accumulating evidence indicates that conventional therapies often fail to eradicate carcinoma cells that have entered the CSC state via activation of the EMT programme, thereby permitting CSC-mediated clinical relapse. In this Review, we summarize our current understanding of the link between the EMT programme and the CSC state, and also discuss how this knowledge can contribute to improvements in clinical practice.

The Environment and Directed Technical Change

Abstract: This paper introduces endogenous and directed technical change in a growth model with environmental constraints and limited resources. A unique final good is produced by combining inputs from two sectors. One of these sectors uses "dirty" machines and thus creates environmental degradation. Research can be directed to improving the technology of machines in either sector. We characterize dynamic tax policies that achieve sustainable growth or maximize intertemporal welfare, as a function of the degree of substitutability between clean and dirty inputs, environmental and resource stocks, and cross-country technological spillovers. We show that: (i) in the case where the inputs are sufficiently substitutable, sustainable long-run growth can be achieved with temporary taxation of dirty innovation and production; (ii) optimal policy involves both "carbon taxes" and research subsidies, so that excessive use of carbon taxes is avoided; (iii) delay in intervention is costly: the sooner and the stronger is the policy response, the shorter is the slow growth transition phase; (iv) the use of an exhaustible resource in dirty input production helps the switch to clean innovation under laissez-faire when the two inputs are substitutes. Under reasonable parameter values (corresponding to those used in existing models with exogenous technology) and with sufficient substitutability between inputs, it is optimal to redirect technical change towards clean technologies immediately and optimal environmental regulation need not reduce long-run growth. We also show that in a two-country extension, even though optimal environmental policy involves global policy coordination, when the two inputs are sufficiently substitutable environmental regulation only in the North may be sufficient to avoid a global disaster.