Modelling children's negation errors using probabilistic learning in MOSAIC.

Cognitive models of language development have often been used to simulate the pattern of errors in children’s speech. One relatively infrequent error in English involves placing inflection to the right of a negative, rather than to the left. The pattern of negation errors in English is explained by Harris & Wexler (1996) in terms of very early knowledge of inflection on the part of the child. We present data from three children which demonstrates that although negation errors are rare, error types predicted not to occur by Harris & Wexler do occur, as well as error types that are predicted to occur. Data from MOSAIC, a model of language acquisition, is also presented. MOSAIC is able to simulate the pattern of negation errors in children’s speech. The phenomenon is modelled more accurately when a probabilistic learning algorithm is used

Modeling children’s case marking errors with MOSAIC

We present a computational model of early grammatical development which simulates case-marking errors in children’s early multi-word speech as a function of the interaction between a performance-limited distributional analyser and the statistical properties of the input. The model is presented with a corpus of maternal speech from which it constructs a network consisting of nodes which represent words or sequences of words present in the input. It is sensitive to the distributional properties of items occurring in the input and is able to create ‘generative’ links between words which occur frequently in similar contexts, building pseudo-categories. The only information received by the model is that present in the input corpus. After training, the model is able to produce child-like utterances, including case-marking errors, of which a proportion are rote-learned, but the majority are not present in the maternal corpus. The latter are generated by traversing the generative links formed between items in the network

IMPROVEMENTS IN DATABASE CONCURRENCY CONTROL WITH LOCKING

Various techniques have been proposed to ensure the safe, concurrent execution of a set of database transactions. Locking protocols are the most prominent and widely used of these techniques, with two-phase locking and tree-locking being but two examples of these protocols. A locking protocol defines a general set of restrictions on the placement of lock and unlock steps within transactions. In this paper we show that it is possible to further increase the potential level of concurrency of a set of transactions, within the context of a specific locking protocol, by further restricting the placement of lock and unlock steps within each transaction. We also discuss a variation of the tree-locking protocol that allows transaction to be locked with respect to a dynamically changing set of tree structures. In addition we define and discuss the concept of a concurrency cost function for a locked transaction. This cost function measures the potential for conflict of a transaction with other transactions.Information Systems Working Papers Serie

A New Species of Melita (Amphipoda:Gammaridae) from the Marshall Islands, Micronesia

During the summers of 1968 and 1969, the author collected and studied amphipods from intertidal and subtidal lagoon habitats of three atolls (Eniwetok, Kwajalein, and Majuro) in the Marshall Islands, Micronesia. Particular emphasis was placed on collecting from calcareous sands and gravels, since most workers to date have reported on the more abundant epifaunal species (Schellenberg, 1938; Barnard, 1965). In addition, efforts were made to collect complete series of life history stages, and to study morphological variations, behavior, and general ecology of the more abundant species

Modelling optional infinitive phenomena: A computational account of tense optionality in children’s speech

The Optional Infinitive hypothesis proposed by Wexler (1994) is a theory of children’s early grammatical development that can be used to explain a variety of phenomena in children’s early multi-word speech. However, Wexler’s theory attributes a great deal of abstract knowledge to the child on the basis of rather weak empirical evidence. In this paper we present a computational model of early grammatical development which simulates Optional Infinitive phenomena as a function of the interaction between a performance-limited distributional analyser and the statistical properties of the input. Our findings undermine the claim that Optional Infinitive phenomena require an abstract grammatical analysis

Factors affecting patients' trust and confidence in GPs: evidence from the English national GP patient survey.

OBJECTIVES: Patients' trust in general practitioners (GPs) is fundamental to effective clinical encounters. Associations between patients' trust and their perceptions of communication within the consultation have been identified, but the influence of patients' demographic characteristics on these associations is unknown. We aimed to investigate the relative contribution of the patient's age, gender and ethnicity in any association between patients' ratings of interpersonal aspects of the consultation and their confidence and trust in the doctor. DESIGN: Secondary analysis of English national GP patient survey data (2009). SETTING: Primary Care, England, UK. PARTICIPANTS: Data from year 3 of the GP patient survey: 5 660 217 questionnaires sent to patients aged 18 and over, registered with a GP in England for at least 6 months; overall response rate was 42% after adjustment for sampling design. OUTCOME MEASURES: We used binary logistic regression analysis to investigate patients' reported confidence and trust in the GP, analysing ratings of 7 interpersonal aspects of the consultation, controlling for patients' sociodemographic characteristics. Further modelling examined moderating effects of age, gender and ethnicity on the relative importance of these 7 predictors. RESULTS: Among 1.5 million respondents (adjusted response rate 42%), the sense of 'being taken seriously' had the strongest association with confidence and trust. The relative importance of the 7 interpersonal aspects of care was similar for men and women. Non-white patients accorded higher priority to being given enough time than did white patients. Involvement in decisions regarding their care was more strongly associated with reports of confidence and trust for older patients than for younger patients. CONCLUSIONS: Associations between patients' ratings of interpersonal aspects of care and their confidence and trust in their GP are influenced by patients' demographic characteristics. Taking account of these findings could inform patient-centred service design and delivery and potentially enhance patients' confidence and trust in their doctor

THE HISTORICAL RELATIONAL DATA MODEL (HRDM) AND ALGEBRA BASED ON LIFESPANS

Critical to the design of an historical database model is the representation of the âexistenceâ of objects across the temporal dimension -- for example, the "birth," "death," or "rebirth" of an individual, or the establishment or dis-establishment of a relationship. The notion of the "lifespan" of a database object is proposed as a simple framework for expressing these concepts. An object's lifespan is simply those periods of time during which the database models the properties of that object. In this paper we propose the historical relational data model (HRDM) and algebra that is based upon lifespans and that views the values of all attributes as functions from time points to simple domains. The model that we obtain is a consistent extension of the relational data model, and provides a simple mechanism for providing both time-varying data and time-varying schemes.Information Systems Working Papers Serie