Perseverers, recencies and deferrers : new experimental evidence for multiple inference strategies in understanding

In the course of understanding a text, a succession of decision points arise at which readers are faced with the task of choosing among alternative possible interpretations ofthattext. We present new experimental evidence that different readers use different inference strategies to guide their inference behavior during understanding. The choices available to an understander range from various alternative inferential paths to the option of making no inference at a particular point, leaving a 'loose end'. Different inference strategies result in observably different behaviors during understanding, including consistent differences in reading times, and different interpretations of a text. The preliminary experimental results given here so far consistently support a previously published set of hypotheses about the inference process that we have called Judgmental Inference theory

Parsing with parallelism : a spreading-activation model of inference processing during text understanding

The past decade of reseatch in Natural Language Processing has universally recognized that, since natural language input is almost always ambiguous with respect to its pragmatic implications, its syntactic parse, and even its lexical analysis (i.e., choice of correct word-sense for an ambiguous word), processing natural language input requires decisions about word meanings, syntactic structure, and pragmatic inferences. The lexical, syntactic, and pragmatic levels of inferencing are not as disparate as they have often been treated in both psychological and artificial intelligence research. In fact, these three levels of analysis interact to form a joint interpretation of text.ATLAST (A Three-level Language Analysis SysTem) is an implemented integration of human language understanding at the lexical, the syntactic, and the pragmatic levels. For psychological validity, ATLAST is based on results of experiments with human subjects. The ATLAST model uses a new architecture which was developed to incorporate three features: spreading activation memory, two-stage syntax, and parallel processing of syntax and semantics. It is also a new framework within which to interpret and tackle unsolved problems through implementation and experimentation

The Impact of Differential Cost Sharing of Non-Steroidal Anti-Inflammatory Agents on the Use and Costs of Analgesic Drugs

OBJECTIVE: To estimate the effect of differential cost sharing (DCS) schemes for non-steroidal anti-inflammatory drugs (NSAIDs) on drug subsidy program and beneficiary expenditures. DATA SOURCES/STUDY SETTING: Monthly aggregate claims data from Pharmacare, the public drug subsidy program for seniors in British Columbia, Canada over the period 1989-11 to 2001-06. STUDY DESIGN: DCS limits insurance reimbursement of a group of therapeutically similar drugs to the cost of the lowest priced drugs, with beneficiaries responsible for costs above the reimbursement limit. Pharmacare introduced two different forms of DCS, generic substitution (GS) and reference pricing (RP), in April 1994 and November 1995, respectively, to the NSAIDs. Under GS, generic and brand versions of the same NSAID are considered interchangeable, whereas under RP different NSAIDs are. We extrapolated average reimbursement per day of NSAID therapy over the months before GS and RP to estimate what expenditures would have been without the policies. These counterfactual predictions were compared to actual values to estimate the impact of the policies; the estimated impacts on reimbursement rates were multiplied by the post-policy volume of NSAIDS dispensed, which appeared unaffected by the policies, to estimate expenditure changes. DATA COLLECTION: The cleaned NSAID claims data, obtained from Pharmacare’s databases, were aggregated by month and by their reimbursement status under the GS and RP policies. PRINCIPAL FINDINGS: After RP, program expenditures declined by $22.7 million, or$4 million annually, cutting expenditure by half. Most savings accrued from the substitution of low cost NSAIDs for more costly alternatives. About 20% of savings represented expenditures by seniors who elected to pay for partially-reimbursed drugs. GS produced one quarter the savings of RP. CONCLUSIONS: RP of NSAIDs achieved its goal of reducing drug expenditures and was more effective than GS. The effects of RP on patient health and associated health care costs remain to be investigated.Reference pricing; generic substitution; prescription drugs; drug cost containment; NSAIDs.

The structure of preserved information in quantum processes

We introduce a general operational characterization of information-preserving structures (IPS) -- encompassing noiseless subsystems, decoherence-free subspaces, pointer bases, and error-correcting codes -- by demonstrating that they are isometric to fixed points of unital quantum processes. Using this, we show that every IPS is a matrix algebra. We further establish a structure theorem for the fixed states and observables of an arbitrary process, which unifies the Schrodinger and Heisenberg pictures, places restrictions on physically allowed kinds of information, and provides an efficient algorithm for finding all noiseless and unitarily noiseless subsystems of the process

Investigating xylem embolism formation, refilling and water storage in tree trunks using frequency domain reflectometry

Trunks of large trees play an important role in whole-plant water balance but technical difficulties have limited most hydraulic research to small stems, leaves, and roots. To investigate the dynamics of water-related processes in tree trunks, such as winter embolism refilling, xylem hydraulic vulnerability, and water storage, volumetric water content (VWC) in the main stem was monitored continuously using frequency domain moisture sensors in adult Betula papyrifera trees from early spring through the beginning of winter. An air injection technique was developed to estimate hydraulic vulnerability of the trunk xylem. Trunk VWC increased in early spring and again in autumn, concurrently with root pressure during both seasons. Diurnal fluctuations and a gradual decrease in trunk VWC through the growing season were observed, which, in combination with VWC increase after significant rainfall events and depletion during periods of high water demand, indicate the importance of stem water storage in both short- and long-term water balance. Comparisons between the trunk air injection results and conventional branch hydraulic vulnerability curves showed no evidence of ‘vulnerability segmentation’ between the main stem and small branches in B. papyrifera. Measurements of VWC following air injection, together with evidence from air injection and xylem dye perfusion, indicate that embolized vessels can be refilled by active root pressure but not in the absence of root pressure. The precise, continuous, and non-destructive measurement of wood water content using frequency domain sensors provides an ideal way to probe many hydraulic processes in large tree trunks that are otherwise difficult to investigate.Organismic and Evolutionary Biolog

Quantum Error Correction of Observables

A formalism for quantum error correction based on operator algebras was introduced in [1] via consideration of the Heisenberg picture for quantum dynamics. The resulting theory allows for the correction of hybrid quantum-classical information and does not require an encoded state to be entirely in one of the corresponding subspaces or subsystems. Here, we provide detailed proofs for the results of [1], derive a number of new results, and we elucidate key points with expanded discussions. We also present several examples and indicate how the theory can be extended to operator spaces and general positive operator-valued measures.Comment: 22 pages, 1 figure, preprint versio

Science lives: School choices and ‘natural tendencies’

An analysis of 12 semi-structured interviews with university-based scientists and non-scientists illustrates their life journeys towards, or away from, science and the strengths and impact of life occurrences leading them to choose science or non-science professions. We have adopted narrative approaches and used Mezirow's transformative learning theory framework. The areas of discussion from the result have stressed on three main categories that include ‘smooth transition’, ‘incremental wavering transition' and ‘transformative transition’. The article concludes by discussing the key influences that shaped initial attitudes and direction in these people through natural inclination, environmental inspirations and perceptions of science