Design of a Novel Antenna Array Beamformer Using Neural Networks Trained by Modified Adaptive Dispersion Invasive Weed Optimization Based Data

A new antenna array beamformer based on neural networks (NNs) is presented. The NN training is performed by using optimized data sets extracted by a novel Invasive Weed Optimization (IWO) variant called Modified Adaptive Dispersion IWO (MADIWO). The trained NN is utilized as an adaptive beamformer that makes a uniform linear antenna array steer the main lobe towards a desired signal, place respective nulls towards several interference signals and suppress the side lobe level (SLL). Initially, the NN structure is selected by training several NNs of various structures using MADIWO based data and by making a comparison among the NNs in terms of training performance. The selected NN structure is then used to construct an adaptive beamformer, which is compared to MADIWO based and ADIWO based beamformers, regarding the SLL as well as the ability to properly steer the main lobe and the nulls. The comparison is made considering several sets of random cases with different numbers of interference signals and different power levels of additive zero-mean Gaussian noise. The comparative results exhibit the advantages of the proposed beamformer

Food involvement and food purchasing behaviour

This paper investigates the factors affecting product class involvement for food. Factors affecting specific aspects of involvement are also explored. The aim is to determine the factors that affect involvement with food and sketch the profile of consumers more likely to be involved or not involved with food. Building on the literature a conceptual model is developed and empirically tested using survey data collected from supermarkets in Athens. Data were analyzed using probit and ordered probit analysis and marginal effects were calculated which show how much the level of involvement or importance is affected when a variable is changed. Results show that younger consumers, those with higher education and income that engage in nutritional label use behaviour and do not prepare food for their household are more likely to have low involvement with food. Less distinctive characteristics are apparent for the highly involved consumers. Different consumer profiles are also associated with different aspects of food involvement based on importance attached to price, ease of preparation, nutrition, taste, and brand name.product class involvement, food involvement, consumer behaviour, food shopping, attribute importance, Consumer/Household Economics, Food Consumption/Nutrition/Food Safety,

Heteroskedasticity, the single crossing property and ordered response models

Heteroskedasticity in ordered response models has not garnered enough attention in the literature. Econometric software packages do not handle this problem satisfactorily either. We provide formulas to calculate heteroskedasticity corrected marginal effects and discrete changes using an approach that deals with single crossing property, a very restrictive assumption of ordered response models.

Body Weight Outcomes and Food Expenditures Among Older Europeans: A simultaneous equation approach

We analyze the inter-relationships between body weight outcomes and food expenditures among older Europeans using a simultaneous equation model. Several statistical tests were conducted to assess endogeneity of selected variables, the exogeneity, relevance, and validity of instruments used, and the identification of the model. Our results generally suggest, contrary to normative views, that food-away-from-home expenditure is negatively related to body mass index (BMI). BMI is negatively related to the percentage of food spent away from home.Body Mass Index, food expenditures, simultaneous equations, Agricultural and Food Policy,

When a risky prospect is valued more than its best possible outcome

In this paper, we document a violation of normative and descriptive models of decision making under risk. In contrast to uncertainty effects found by Gneezy, List and Wu (2006), some subjects in our experiments valued certain lotteries more than the best possible outcome. We show that the likelihood of observing this effect is positively related to the probability of winning the lottery and negatively related to the value of the maximum outcome. We also demonstrate that this effect can be partially attributed to subjects’ competitiveness and level of comprehension of the lottery mechanism; the competitiveness effects far outweighing comprehension effects.lottery, risk, competitiveness, Vickrey auctions

Comparison of Cognitive Function after Carotid Artery Stenting versus Carotid Endarterectomy

The effect of carotid artery stenting (CAS) and carotid endarterectomy (CEA) on cognitive function is unclear. Both cognitive improvement and decline have been reported after CAS and CEA. We aimed to compare the changes in postprocedural cognitive function after CAS versus CEA. A systematic qualitative review of the literature was conducted according to the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement for studies evaluating the changes in cognitive function after CAS compared with CEA. Thirteen studies (403 CEAs; 368 CAS procedures) comparing the changes in cognitive function after CEA versus CAS were identified. Most studies did not show significant differences in overall cognitive function or only showed a difference in a single cognitive test between the two procedures. A definitive conclusion regarding the effect of CAS versus CEA on cognitive function was not possible owing to heterogeneity in definition, method, timing of assessment, and type of cognitive tests. For the same reasons, performing a meta-analysis was not feasible. The lack of standardization of specific cognitive tests and timing of assessment of cognitive function after CAS and CEA do not allow for definite conclusions to be drawn. Larger, adequately-powered and appropriately designed studies are required to accurately evaluate the effect of CAS versus CEA on postprocedural cognitive function

Updates in the diagnosis and management of small-bowel Crohn's disease

Crohn's disease (CD) can affect any part of the GI tract, but small bowel (SB) involvement is present in 80% of patients with CD; 30% have exclusive SB disease [1] presenting a diagnostic challenge due to the inaccessibility of standard endoscopic techniques. Accurate assessment of treatment response [2] and regular monitoring are crucial to prevent surgery and to identify patients at risk of relapse and/or complications before the onset of clinical symptoms [3]. Ileocolonoscopy (IC) is considered the gold standard for evaluating mucosal healing (MH) in CD, but it is invasive and costly [4] and only allows visualization of the terminal ileum (TI). The CALM study has demonstrated that C-reactive protein (CRP) and faecal calprotectin (FCP) can be effective surrogate markers of MH and help guide treatment [5]. Nonetheless, their efficacy is limited [6] as approximately 30% of patients do not present with elevated CRP levels during relapse [7] and the correlation between FCP and active SB disease is weak [8]. Thus, CD requires a multidisciplinary approach. We aim to provide an overview of recent advances in the diagnosis and management of small bowel CD

Simultaneous multi-frequency single-pulse properties of AXP XTE J1810-197

We have used the 76-m Lovell, 94-m equivalent WSRT and 100-m Effelsberg radio telescopes to investigate the simultaneous single-pulse properties of the radio emitting magnetar AXP XTE J1810-197 at frequencies of 1.4, 4.8 and 8.35 GHz during May and July 2006. We study the magnetar's pulse-energy distributions which are found to be very peculiar as they are changing on time-scales of days and cannot be fit by a single statistical model. The magnetar exhibits strong spiky single giant-pulse-like subpulses, but they do not fit the definition of the giant pulse or giant micropulse phenomena. Measurements of the longitude-resolved modulation index reveal a high degree of intensity fluctuations on day-to-day time-scales and dramatic changes across pulse phase. We find the frequency evolution of the modulation index values differs significantly from what is observed in normal radio pulsars. We find that no regular drifting subpulse phenomenon is present at any of the observed frequencies at any observing epoch. However, we find a quasi-periodicity of the subpulses present in the majority of the observing sessions. A correlation analysis indicates a relationship between components from different frequencies. We discuss the results of our analysis in light of the emission properties of normal radio pulsars and a recently proposed model which takes radio emission from magnetars into consideration.Comment: 15 pages, 11 figures, accepted for publication by MNRA

Exploring the Levinthal limit in protein folding

According to the thermodynamic hypothesis, the native state of proteins is uniquely defined by their amino acid sequence. On the other hand, according to Levinthal, the native state is just a local minimum of the free energy and a given amino acid sequence, in the same thermodynamic conditions, can assume many, very different structures that are as thermodynamically stable as the native state. This is the Levinthal limit explored in this work. Using computer simulations, we compare the interactions that stabilize the native state of four different proteins with those that stabilize three non-native states of each protein and find that the nature of the interactions is very similar for all such 16 conformers. Furthermore, an enhancement of the degree of fluctuation of the non-native conformers can be explained by an insufficient relaxation to their local free energy minimum. These results favor Levinthal's hypothesis that protein folding is a kinetic non-equilibrium process.FCT - Foundation for Science and Technology, Portugal [UID/Multi/04326/2013]; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); Conselho Nacional de Desenvolvimento Cientia co e Tecnologico (CNPq