Complexity parameters for first order classes

We study several complexity parameters for first order formulas and their suitability for first order learning models. We show that the standard notion of size is not captured by sets of parameters that are used in the literature and thus they cannot give a complete characterization in terms of learnability with polynomial resources. We then identify an alternative notion of size and a simple set of parameters that are useful for first order Horn Expressions. These parameters are the number of clauses in the expression, the maximum number of distinct terms in a clause, and the maximum number of literals in a clause. Matching lower bounds derived using the Vapnik Chervonenkis dimension complete the picture showing that these parameters are indeed crucial. This work has been partly supported by NSF Grant IIS-0099446. A preliminary version of this paper appeared in the proceeding of the conference on Inductive Logic Programming 2003. Most of this work was done while M.A. was at Tufts University. Editors: Tamás Horváth and Akihiro Yamamoto     

Age and experience effects in spatial visualization.

Three studies were conducted to investigate effects related to age and experience on measures of spatial visualization ability. All research participants were college-educated men; those in the experienced group were practicing or recently retired architects. The major results of the studies were (a) that increased age was found to be associated with lower levels of performance on several tests of spatial visualization and (b) that this was true both for unselected adults and for adults with extensive spatial visualization experience. These findings seem to suggest that age-related effects in some aspects of cognitive functioning may be independent of experiential influences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A VLSI field-programmable mixed-signal array to perform neural signal processing and neural modeling in a prosthetic system

A very-large-scale integration field-programmable mixed-signal array specialized for neural signal processing and neural modeling has been designed. This has been fabricated as a core on a chip prototype intended for use in an implantable closed-loop prosthetic system aimed at rehabilitation of the learning of a discrete motor response. The chosen experimental context is cerebellar classical conditioning of the eye-blink response. The programmable system is based on the intimate mixing of switched capacitor analog techniques with low speed digital computation; power saving innovations within this framework are presented. The utility of the system is demonstrated by the implementation of a motor classical conditioning model applied to eye-blink conditioning in real time with associated neural signal processing. Paired conditioned and unconditioned stimuli were repeatedly presented to an anesthetized rat and recordings were taken simultaneously from two precerebellar nuclei. These paired stimuli were detected in real time from this multichannel data. This resulted in the acquisition of a trigger for a well-timed conditioned eye-blink response, and repetition of unpaired trials constructed from the same data led to the extinction of the conditioned response trigger, compatible with natural cerebellar learning in awake animals.     

Dietary fat ratios and liver plasma membrane lipid composition

Male Sprague-Dawley weanling rats were fed isocaloric diets consisting of 10% (by wt) fat. The six groups differed in the ratio of corn oil and butter fat present in the diets such that: 10C, 10% corn oil (C); 8C2B, 8% C/2% butter fat (B); 6C4B, 6% C/4% B; 4C6B, 4% C/6% B; 2C8B, 2% C/8% B; and 10B, 10% B. Liver plasma membranes were analyzed for fatty acid composition and cholesterol/phospholipid molar ratio. The 18∶2n−6 content was constant in the 10C and 8C2B diets and then decreased linearly through the 2C8B diet. The 20∶4n−6 and 18∶1n−9 contents were constant except in the 10B diet, in which a significant decrease and increase, respectively, were observed. The cholesterol/phospholipid molar ratio increased between the 10C and 6C4B diets and subsequently (4C6B and 10B diets) remained constant. This data indicates that changes in n−6 fatty acid content in the liver plasma membrane are directly related to dietary intake only for 18∶2n−6. Arachidonic acid content in the membrane is maintained at a constant level until the linoleic acid content of the diet is reduced to 0.5% of calories. It also indicates that the cholesterol content of the membrane becomes saturated and does not increase with increasing concentrations of saturated fat in the diet. Presented in part at the FASEB Meeting, Washington, D.C., April, 1987.     

A fast display method for volumetric data

Presented is a fast display method for volumetric data sets, which involves a slicebased method for extracting potentially visible voxels to represent visible surfaces. For a given viewing direction, the number of visible voxels can be trimmed further by culling most of the voxels not visible from that direction. The entire 3D array of voxels is also present for invasive operations and direct access to interior structures. This approach has been integrated on a low-cost graphic engine as an interactive system for craniofacial surgical planning that is currently in clinical use.     

Predicting optimal solution cost with conditional probabilities

Heuristic search algorithms are designed to return an optimal path from a start state to a goal state. They find the optimal solution cost as a side effect. However, there are applications in which all one wants to know is an estimate of the optimal solution cost. The actual path from start to goal is not initially needed. For instance, one might be interested in quickly assessing the monetary cost of a project for bidding purposes. In such cases only the cost of executing the project is required. The actual construction plan could be formulated later, after bidding. In this paper we propose an algorithm, named Solution Cost Predictor (SCP), that accurately and efficiently predicts the optimal solution cost of a problem instance without finding the actual solution. While SCP can be viewed as a heuristic function, it differs from a heuristic conceptually in that: 1) SCP is not required to be fast enough to guide search algorithms; 2) SCP is not required to be admissible; 3) our measure of effectiveness is the prediction accuracy, which is in contrast to the solution quality and number of nodes expanded used to measure the effectiveness of heuristic functions. We show empirically that SCP makes accurate predictions on several heuristic search benchmarks.     

Veterinary drug residues in seafood inspected by the European Union, United States, Canada, and Japan from 2000 to 2009

Veterinary drugs are used to treat or prevent a wide array of production-related diseases in aquaculture. Residues of these drugs in seafood products may pose risks to consumers, prompting governments to set drug residue tolerance levels and inspect seafood for violations of these standards. This study characterizes veterinary drug inspection policies and violations among four inspecting bodies (European Union (E.U.), United States (U.S.), Canada, and Japan), using government-collected veterinary drug violation data from 2000 to 2009. Most veterinary drug violations were detected in species that are commonly farm-raised. Asian seafood products, including shrimp and prawns, catfish (or fish sold as catfish), crab, tilapia, eel, and Chilean salmon were most frequently in violation of veterinary drug residue standards. Vietnam had the greatest number of violations among exporting countries. Concentrations of most veterinary drugs in seafood found in violation did not differ between inspecting bodies that reported drug concentrations. Transparency in seafood inspection reporting varied widely among inspecting bodies. Estimation of violations in the untested fraction of seafood was precluded by a lack of information from inspecting bodies regarding the distinction between targeted and random sampling. Increased transparency could facilitate a more rigorous characterization of public health risks from consuming imported seafood.     

Phase stability of rare earth sesquioxides with grain size controlled in the nanoscale

Rare earth oxides are important materials due to their chemical and physical properties. The rare earth sesquioxides (RESOXs) possess a cubic, monoclinic, or hexagonal structure, depending on pressure, temperature and ionic radius. When RESOXs take the form of single crystalline grains with diameter in the nanoscale range (nanocrystals), it is suspected that the grain size determines the phase stability as well. RESOXs with medium ionic radius such as Gd₂O₃, Eu₂O₃ and Sm₂O₃ in the low temperature range up to 900°C may take the monoclinic structure or the cubic structure, depending on the synthesis process. The structure determining factor can be, besides temperature, also the grain size. In order to determine the stable structure taking into account grain size as a parameter, we produced Gd₂O₃ and Sm₂O₃ nanocrystals embedded in a neutral MgO matrix. This way, we prevented grain growth during annealing. For comparison, we annealed pure Gd₂O₃ and Sm₂O₃ nanocrystals in which temperature increase caused grain growth, as in traditional experiments for phase stability determination. We have shown that for coarse grained materials at low temperature monoclinic is the stable structure. For nano-sized crystallites, cubic is the stable structure. This explains the controversial results as far as which phase is the stable one below 900°C and permits to program the needed structure by controlling crystallization kinetics and grain growth.