Investigation of the modulation of spatial frequency preferences with attentional load within human visual cortex

Performance in visual tasks improves with attention, and this improvement has been shown to stem, in part, from changes in sensory processing. However, the mechanism by which attention affects perception remains unclear. Considering that neurons within the visual areas are selective for basic image statistics, such as orientation or spatial frequency (SF), it is plausible that attention modulates these sensory preferences by altering their so-called ‘tuning curves’. The goal of this project is to investigate this possibility by measuring and comparing the SF tuning curves across a range of attentional states in humans. In Experiment 1, a model-driven approach to fMRI analysis was introduced that allows for fast and efficient estimation of population spatial frequency tuning (pSFT) for individual voxels within human visual cortices. Using this method, I estimated pSFTs within early visual cortices of 8 healthy, young adults. Consistent with previous studies, the estimated SF optima showed a decline with retinotopic eccentricity. Moreover, my results suggested that the bandwidth of pSFT depends on eccentricity, and that populations with lower SF peaks possess broader bandwidths. In Experiment 2, I proposed a new visual task, coined the Numerosity Judgement Paradigm (NJP), for fine-grained parametric manipulation of attentional load. Eight healthy, young adults performed this task in an MRI scanner, and the analysis of the BOLD signal indicated that the activity within the putative dorsal attention network was precisely modulated as a function of the attentional load of the task. In Experiment 3, I used the NJP to modulate attentional load, and exploited the model-based approach to estimate pSFTs under different attentional states. fMRI results of 9 healthy, young adults did not reveal any changes in either peak or the bandwidth of the pSFTs with attentional load. This study yields a full visuocortical map of spatial frequency sensitivity and introduces a new paradigm for modulating attentional load. Although under this paradigm I did not find any changes in SF preferences within human visual areas with attentional load, I cannot preclude the possibility that changes emerge under different attentional manipulations

Incorporating FCM and Back Propagation Neural Network for Image Segmentation

Hybrid image segmentation is proposed in this paper. The input image is firstly preprocessed in order to extract the features using Discrete Wavelet Transform (DWT) .The features are then fed to Fuzzy C-means algorithm which is unsupervised. The membership function created by Fuzzy C-means (FCM) is used as a target to be fed in neural network. Then the Back Propagation Neural network (BPN) has been trained based on targets which is obtained by (FCM) and features as input data. Combining the FCM information and neural network in unsupervised manner lead us to achieve better segmentation .The proposed algorithm is tested on various Berkeley database gray level images

Flood zoning and developing strategies to increase resilience against floods with a crisis management approach

Assessment and planning of crisis management with the approach to natural flood disasters include many factors. In this regard, one of the basic principles of crisis management is based on the resilience of urban infrastructure against floods. This study developed strategies to increase resilience by flood zoning and crisis management. The investigation of the current situation shows that despite the efforts being made, the climatic and environmental conditions of the rivers, the settlements of the infiltration basin, the constructions, and the location inaccuracy of the following structures indicate many challenges in managing the current situation in various components of crisis management. In this regard, the main direction of this article is to evaluate the urban resilience of the Khuzestan region against floods based on a crisis management approach and technique for order preference by similarity to ideal solution (TOPSIS) and Fuzzy weighting methods using geographic information system (GIS)

Risk estimation of heavy metals from consumption of silver pomfret and tiger tooth croaker in Hormozagan Province

In the present study, accumulation of manganese, cadmium, zinc, iron and copper in the commercially fish species (silver pomfret and tiger tooth croaker) caught from Bandarabbas coasts at 2010 was measured and the risk of daily intake of them in Hormozagan urban population was estimated. The average concentrations (µ/g dry weight) of manganese, cadmium, zinc, iron, and copper in the muscle tissue of silver pomfret were 1.248, 0.217, 14.444, 2.397 and 3.300, respectively, while the concentration of them in tiger tooth croaker were 1.009, 0.403, 12.564, 4.467 and 2.366, respectively. According to fish consumption rate, urban populations of the province were divided into four groups; low, medium, high and very high. The target hazard quotient (THQ) in each group calculated separately. The THQ of all groups were much lower than 1 in the two fish. The results showed that urban populations of the province have not any risk due to accumulation of the studied heavy metals

Innovative operation strategies and performance outcomes of Malaysia manufacturing small and medium enterprises

Innovation in operations is important for all small and medium enterprises (SMEs) especially in developing economies. This study examined the direct and indirect relations between strategic orientation, current and future innovative operation strategies, environmental uncertainties and the performance of Malaysia SMEs. Drawing on Market Based View (MBV), Resource Based View (RBV) and Dynamic Capabilities View (DCV) theories, a theoretical model consisting of firm’s strategic orientation, current innovative operation strategy, future innovative operation strategy, firm’s market performance, firm’s operational performance and environmental uncertainties was developed. Data were collected through a survey of 210 Malaysian manufacturing SMEs. A structural equation modeling (SEM) procedure was employed to test the hypotheses. The theoretical model was validated by empirical findings. This study found that strategic orientation positively influences a firm’s innovation in current and related future operations. Thus, a clear strategic orientation aligned with innovative operation strategy is a pre-requisite for SMEs. It was also confirmed that innovation of current and future operations could affect the operational and market performance of the firm. Furthermore, under conditions of uncertainty, firms which emphasize innovation in their operations are more likely to achieve better performance and could outperform their rivals. Drawing upon these findings, this study offers several important theoretical and managerial implications and opens up new areas for future research

Influence of genotype and plant growth regulator on somatic embryogenesis in rapeseed (Brassica napus L.)

Two genotypes of Brassica napus species (Talayeh and RGS003) and the explants segment (hypocotyls and cotyledon) were tested for their potential to produce somatic embryos in in vitro condition. The effect of genotype, different explants and also different concentrations of plant growth regulators (PGRs) including: -naphthalene acetic acid (NAA), 2,4-Dichlorophenoxy acetic acid (2,4-D), 6-benzyl amino purine (BAP), were investigated. The basal medium was Murashige and Skoog (MS)supplemented with 2% sucrose and 1% agar. Explants plated on different callus induction medium and each 4 week was subculture in the same medium. The results showed that ‘Talayeh’, in terms of regeneration, had significant difference with RGS003 and produce more somatic embryos. In this genotype, modified MS medium containing 2% sucrose, 6 mg l-1 sodium chloride (NaCl), 3 mg l-1 BAP, 2 mg l-1 NAA and 2 mg l-1 2,4-D was the most efficient medium for somatic embryogenesis in ‘Talayeh’and also, hypocotyl explants were found to be more suitable than cotyledon for somatic embryogenesis

Determination of heavy metal (lead and cadmium) concentrations in liver and muscle tissue of Indian mackerel (Rastrelliiger kanagurta) in Persian Gulf

This study was conducted to compare heavy metal concentrations including lead and cadmium in liver and muscle tissues of Indian mackerel (Rastrelliiger Kanagurta) in Bandar Lengeh, Hormoz island, Hengam island and Kolahi regions. In current research, the influence of season, sex and size (length and weight) on Pb and Cd concentrations in Indian mackerel was investigated in these areas. Then Lead and cadmium concentrations in muscle tissues were compared with international standards for human consumption. Sampling was performed in summer and winter. Metal concentrations of organs were assessed by dry digestion method and atomic absorption spectrometer (AAS). Results showed that there are statistically significant differences between concentrations of lead and cadmium in liver and tissues of the fish in these regions (Bandar Lengeh, Hormoz, Hengam and Kolahi) (p0.05). In addition, there is no correlation between lead and cadmium concentrations in muscle and liver of Indian mackerel with size (length and weight) (p>0.05)

Quantitative Evaluation by Protection Layer Analysis (LOPA) for Equipment in Imam Khomeini Petrochemical Aromatic Unit

Background: In the petrochemical industries, accidents are generally catastrophic which endanger human, environment and economic. In the industries, there is a wide range of flammable and toxic substances that affect health and safety of workers. They have also adverse effects on society. Numerical risk and impact assessment as well as design for protective layers against catastrophic events are necessary for designing process units.Methods: First, the occupational-process and environmental safety hazards were measured by hazard and operability (HAZOP) and environmental failure mode and effects analysis (EFMEA) techniques. Then, the risk was assessed using the layer and operability analysis (LOPA) method.Results: The results showed that a total of 50 safe and health items and 37 environmental risks were identified by HAZOP and EFMEA methods in Imam Khomeini Petrochemical Aromatic Unit. There were 17, 19 and 14 items with low, medium and high level risk, respectively.Conclusion: This study showed that the LOPA method is more comprehensive than hazard identification methods for the analysis of protective layers. The important actions were blockage of the excess gas to the flare and release the H2S gas. Also, evaluation of the environmental aspects of aromatic unit activities showed that air pollutant production in the power supply unit, waste disposal of reactor tank, waste disposal of condensate tank and reactor fire and explosion were at a high level risk