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Superabsorbent hydrogels (HGs) are three-dimensional, polymeric networks that have been shown to increase soil water holding capacity, but little is known about their effect on nitrogen (N) transformations in soil. The objective of this study was to determine the effect of two types of HGs (polyacrylate (TS) or cellulose-based (H30)) applied as soil amendment on pH, urea hydrolysis, nitrification, NH3 volatilization, and soil respiration in two soils receiving urea or ammonium sulfate. Separate studies with each HG in each of two soils (four studies) were conducted with an acidic sandy loam collected in Georgia (USA) and a basic sandy loam collected in the Veneto region of Italy. The results showed that the addition of TS increased the pH of the acidic soil, whereas H30 did not have a major effect on soil pH in either soil. In the acidic soil receiving urea, H30 increased nitrification, whereas TS decreased initial nitrification. Neither HG affected urea hydrolysis, N immobilization and NH3 volatilization in either soil, but both HGs increased soil respiration in the basic soil, possibly due to HG degradation by microorganisms. These results show that the use of HGs together with N fertilizers may affect soil pH, nitrification, and respiration. [ABSTRACT FROM AUTHOR]

Issues concerning the orientation of fullerene bisadducts dissolved in E7 are discussed. It was possible to investigate preferential orientation of molecules embedded in a nematic liquid crystalline matrix.

Recurrent neural networks processing symbolic strings can be regarded as adaptive neural parsers. Given a set of positive and negative examples, picked up from a given language, adaptive neural parsers can effectively be trained to infer the language grammar. In this paper we use adaptive neural parsers to face the problem of inferring grammars from examples that are corrupted by a kind of noise that simply changes their membership. We propose a training algorithm, referred to as hybrid finite state filter (HFF), which is based on a parsimony principle that penalizes the development of complex rules. We report very promising experimental results showing that the proposed inductive inference scheme is indeed capable of capturing rules, while removing noise. Index Terms - Finite-state automata, grammatical inference, iterated function systems, recurrent neural networks.

Many researchers have recently focused their efforts on devising efficient algorithms, mainly based on optimization schemes, for learning the weights of recurrent neural networks. As in the case of feedforward networks, however, these learning algorithms may get stuck in local minima during gradient descent, thus discovering sub-optimal solutions. This paper analyses the problem of optimal learning in recurrent networks by proposing conditions that guarantee local minima free error surfaces. An example is given that also shows the constructive role of the proposed theory in designing networks suitable for solving a given task. Moreover, a formal relationship between recurrent and static feedforward networks is established such that the examples of local minima for feedforward networks already known in the literature can be associated with analogous ones in recurrent networks.

Two pyrene based organogelators in which the pyrene moiety has been linked to the diphenylalanine dipeptide have been synthesized. We show how the solvent can tune both the morphology and the optical properties of the organogels: spherical aggregates with quenched emission were obtained in acetonitrile, whereas an entangled fibrillar network with enhanced emission was formed in o-dichlorobenzene. Fourier transform infrared spectroscopy, circular dichroismand nuclearmagnetic resonance spectroscopy experiments suggest that bothp-p stacking and hydrogen bonding contribute to the formation of the supramolecular networks. Ultraviolet-visible and steady state emission studies demonstrated the formation of I-aggregates in acetonitrile. In contrast, in o-dichlorobenzene, the formation of J-type aggregates leads to assemblieswith enhancedemission. These results give some insight into the important role of the gelling solvent in the morphology of the supramolecular gels and may help in the design of new soft-materials. [ABSTRACT FROM AUTHOR]

We report in this communication the synthesis of star-shaped carbon quantum dots-(poly-β-benzyl-L-glutamate) conjugates that self-assemble into microstructures and retain the characteristic emission properties of the native dots. Dots were used either as an initiator to give a daisy-like peptide-polymer structure or as capping agents towards more elaborated hybrid nanostructures. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study was to assess incidence of and risk factors for recurrent cardiovascular disease (CVD) in type 2 diabetes.Research Design and Methods: We estimated the incidence of recurrent cardiovascular events in type 2 diabetic patients, aged 40-97 years, followed by a network of diabetes clinics. The analysis was conducted separately for 2,788 patients with CVD at enrollment (cohort A) and for 844 patients developing the first episode during the observation period (cohort B).Results: During 4 years of follow-up, in cohort A the age-adjusted incidence of a recurrent event (per 1,000 person-years) was 72.7 (95% CI 58.3-87.1) in men and 32.5 (21.2-43.7) in women, whereas in cohort B it was 40.1 (17.4-62.9) in men and 22.4 (12.9-32.0) in women. After controls were included for potential predictors (familial CVD, obesity, smoking, diabetes duration, glycemic control, microvascular complications, geographic area, and antihypertensive and lipid-lowering treatment), male sex, older age, and insulin use were significant independent risk predictors (cohort A) and serum triglyceride levels >/=1.69 mmol/l emerged as the only metabolic (negative) prognostic factor (cohort B). In both cohorts, a prior CVD episode, especially myocardial infarction, was by far the strongest predictor of recurrent CVD.Conclusions: Approximately 6% of unselected diabetic patients in secondary prevention develop recurrent major CVD every year. Those with long-standing previous CVD show a higher incidence of recurrence. Male sex, age, high triglyceride levels, and insulin use are additional predictors of recurrence. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Cardiovascular disease (CVD) is the main cause of morbidity/mortality in diabetes. We set forth to determine incidence and identify predictors (including microvascular complications and treatment) of first coronary heart disease (CHD) event in CVD-free type 2 diabetic patients. RESEARCH DESIGN AND METHODS: A cohort of 6,032 women and 5,612 men, sampled from a nationwide network of hospital-based diabetes clinics, was followed up for 4 years. Baseline assessment included retinopathy, nephropathy, and foot ulcers. First CHD events (myocardial infarction, coronary artery bypass grafting, percutaneous transluminal coronary angioplasty, and electrocardiogram-proven angina) were analyzed for 29,069 person-years. RESULTS: The age-standardized incidence rate (per 1,000 person-years) of first CHD event (n = 881) was 28.8 (95% CI 5.4-32.2) in men and 23.3 (20.2-26.4) in women. Major CHD (myocardial infarction, coronary artery bypass grafting, and percutaneous transluminal coronary angioplasty) was less frequent in women (5.8 [4.3-7.2]) than in men (13.1 [10.9-15.4]; a sex ratio of 0.5 [0.4-0.6]). Incidence rates of all outcomes were higher in patients with microvascular complications (for major CHD, age-adjusted rate ratios were 1.6 [1.2-2.21] in men and 1.5 [1.0-2.2] in women). By multivariate Cox analysis, age and diabetes duration were risk predictors common in both sexes. In men, glycemic control and treated hypertension were additional independent risk factors, but residing in the south was associated with a significant 29% risk reduction. In women, higher triglycerides/lower HDL cholesterol and microvascular complications were independent risk factors. CONCLUSIONS: In CVD-free patients with type 2 diabetes, risk of first CHD event depends on sex, geographic location, and presence of microvascular disease. Hyperglycemia and hypertension, particularly in men, and diabetic dyslipidemia, especially in women, are risk factors amenable to more aggressive treatment. [ABSTRACT FROM AUTHOR]