Morphology and structure of nylon‐6 crystallized in epoxy resin matrix

Nylon‐6/epoxy resin composite with multiphase morphology has been successfully prepared via polymerization of caprolactam in N‐methylpyrrolidone using N‐acetyl caprolactam as the initiator. This was followed by reactive blending of appropriate amount of the plastic with epoxy resin. The structure of nylon‐6 prepared by solution polymerization is predominantly α [200, 020]_α crystalline form with γ [002]_γ crystalline form as the minor phase. Subsequently, nylon‐6/epoxy composite was prepared at 150°C in a Teflon mold. A remarkable heterogeneous morphology of the fractured surface of the film was observed, consisting of multilayered fiber‐like crystals encapsulated in the epoxy resin matrix. Close inspection of the morphology of the composite revealed a preference of nylon‐6 to crystallize in the crevices and cracks created in glassy epoxy matrix during processing. The crystals seem to nucleate spontaneously and grow radially into spherulites. POLYM. ENG. SCI., 54:858–866, 2014. © 2013 Society of Plastics Engineers     

Gleaner: Creating ensembles of first-order clauses to improve recall-precision curves

Many domains in the field of Inductive Logic Programming (ILP) involve highly unbalanced data. A common way to measure performance in these domains is to use precision and recall instead of simply using accuracy. The goal of our research is to find new approaches within ILP particularly suited for large, highly-skewed domains. We propose Gleaner, a randomized search method that collects good clauses from a broad spectrum of points along the recall dimension in recall-precision curves and employs an “at least L of these K clauses” thresholding method to combine sets of selected clauses. Our research focuses on Multi-Slot Information Extraction (IE), a task that typically involves many more negative examples than positive examples. We formulate this problem into a relational domain, using two large testbeds involving the extraction of important relations from the abstracts of biomedical journal articles. We compare Gleaner to ensembles of standard theories learned by Aleph, finding that Gleaner produces comparable testset results in a fraction of the training time. Editor: Rui Camacho     

Enhanced monocyte tissue factor response after experimental balloon angioplasty in hypercholesterolemic rabbit: inhibition with dietary L-arginine

BACKGROUND: There is evidence that tissue factor (TF) is a major contributor to the thrombogenicity of a ruptured atherosclerotic plaque. Nitric oxide (NO) has antiatherogenic and antithrombotic properties. We investigated whether L-arginine (L-arg), the endogenous precursor of NO, might affect the ability of monocytes to produce TF. METHODS AND RESULTS: We studied TF expression in 18 rabbits with atherosclerosis induced by bilateral iliac damage and 10 weeks of a 2% cholesterol diet. Six weeks after the initiation of the diet, an angioplasty was performed. After angioplasty, the surviving rabbits (n=15) were randomized to receive L-arg (2.25%) supplementation in drinking water (L-arg group, n=8) or no treatment (untreated group, n=7). TF expression was evaluated in mononuclear cells from arterial blood in the presence and absence of endotoxin stimulation. Monocyte TF expression, as assessed with an amidolytic assay, did not differ significantly before or after the induction of atherosclerotic lesions (87+/-15 versus 70+/-12 mU of TF/1000 monocytes, P=NS). Endotoxin-stimulated TF activity increased significantly 4 weeks after angioplasty (138+/-22 versus 70+/-12 mU of TF/1000 monocytes, P=0.02). This increase was blunted by L-arg (43+/-16 mU of TF/1000 monocytes, P=0.01). CONCLUSIONS: This study demonstrates that angioplasty-induced plaque rupture is associated with a marked increase in monocyte TF response that is blunted by the oral administration of L-arg. This suggests that the documented antithrombotic properties of NO may be related in part to an inhibitory effect on monocyte TF response.     

Cognition and metacognition at extreme altitudes on Mount Everest.

The FACTRETRIEVAL2 test battery, which assesses both retrieval of general information from memory and metacognition about that retrieval, was administered to people before and after a recent expedition to Mount Everest and at extreme altitudes above 6,400 m (higher than any mountain in North America or Europe). Major findings were as follows: First, the same extreme altitudes known to impair learning did not affect accuracy or latency of retrieval, and this robustness of retrieval occurred for both recall and forced-choice recognition. Second, extreme altitude did affect metacognition: Climbers showed a decline in their feeling of knowing both while at extreme altitude and after returning to Kathmandu (i.e., both an effect and an aftereffect of extreme altitude). Third, extreme altitude had different effects than alcohol intoxication (previously assessed by T. O. Nelson et al [see PA, Vol 73:29460]). Alcohol intoxication affected retrieval without affecting metacognition, whereas extreme altitude affected metacognition without affecting retrieval; this different pattern for extreme altitude versus alcohol intoxication implies that (a) hypoxia does not always yield the same outcome as alcohol intoxication and (b) neither retrieval nor metacognition is strictly more sensitive than the other for detecting changes in independent variables. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Relationships between severe neonatal thrombocytopenia and maternal characteristics in pregnancies associated with autoimmune thrombocytopenia

A molecular method for the identification of ectomycorrhizae belonging to five species of white truffle is described. The polymerase chain reaction (PCR) and universal primers were used to amplify internal transcribed spacers and 5.8S rDNA, target sequences present in a high number of copies. The amplified products were digested with restriction enzymes in order to detect interspecific polymorphisms. Species-specific restriction fragment length polymorphism patterns were determined for all five species. The use of PCR in conjunction with restriction enzymes provides a sensitive and efficient tool for use in distinguishing ectomycorrhizal species and monitoring inoculated seedlings or field mycorrhizal populations.     

Knowledge-based artificial neural networks

Hybrid learning methods use theoretical knowledge of a domain and a set of classified examples to develop a method for accurately classifying examples not seen during training. The challenge of hybrid learning systems is to use the information provided by one source of information to offset information missing from the other source. By so doing, a hybrid learning system should learn more effectively than systems that use only one of the information sources. KBANN (Knowledge-Based Artificial Neural Networks) is a hybrid learning system built on top of connectionist learning techniques. It maps problem-specific “domain theories”, represented in propositional logic, into neural networks and then refines this reformulated knowledge using backpropagation. KBANN is evaluated by extensive empirical tests on two problems from molecular biology. Among other results, these tests show that the networks created by KBANN generalize better than a wide variety of learning systems, as well as several techniques proposed by biologists.     

Diver and Underwater Television Observations of Fish Behavior in a Great Lakes Commercial Trap Net

Behavior of lake whitefish (Coregonus clupeaformis) and lake trout (Salvelinus namaycush) in commercial trap-net pots was observed by scuba divers and by a low-light sensitive, underwater television (UTV) system. During the day, lake whitefish schooled and swam in circular patterns within the pot, keeping at least 1 m off the lake bottom. Occasionally, lake whitefish that were outside the net were observed swimming in concert with fish inside the pot. Whitefish schools disbanded at dawn and dusk, presumably because of reduced visual acuity during periods of low light. Lake trout were most often in groups of two or three individuals which were generally segregated from whitefish schools. Aggressive, escapement, and feeding behavior were not observed for either species. As nets were lifted, fish became very excited and darted about wildly. Net leads may have elicited schooling responses from fish, causing them to enter the pot. Fish stayed 3 to 5 m away from divers, making observations of behavior difficult. However, divers were able to make some observations which were not possible with UTV. Physical presence of UTV equipment did not alter fish behavior as did diver presence. Compared with divers, UTV could be deployed longer and at lower light levels. UTV also provided a permanent record (video cassette) that could subsequently be reviewed. An integration of UTV and diver observations gave the best understanding offish behavior in trap-net pots.     

A Study of LES Stress and Flux Models Applied to a Buoyant Jet

Large eddy simulation (LES) stress and scalar flux subgrid scale models are evaluated in the context of buoyant jets. Eddy viscosity, eddy diffusivity (including formulations of the generalized gradient diffusion hypothesis), “structure” (Bardina and Leonard), mixed, and dynamic models are scrutinized. The performance of the models is examined in terms of the main flow variables and also with respect to the “internal” behavior of the models in terms of the relative contributions to the turbulent kinetic energy budget.