189 research outputs found

    Structural MRI studies of language function in the undamaged brain

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    In recent years, the demonstration that structural changes can occur in the human brain beyond those associated with development, ageing and neuropathology has revealed a new approach to studying the neural basis of behaviour. In this review paper, we focus on structural imaging studies of language that have utilised behavioural measures in order to investigate the neural correlates of language skills in the undamaged brain. We report studies that have used two different techniques: voxel-based morphometry of whole brain grey or white matter images and diffusion tensor imaging. At present, there are relatively few structural imaging studies of language. We group them into those that investigated (1) the perception of novel speech sounds, (2) the links between speech sounds and their meaning, (3) speech production, and (4) reading. We highlight the validity of the findings by comparing the results to those from functional imaging studies. Finally, we conclude by summarising the novel contribution of these studies to date and potential directions for future research

    Specialization along the Left Superior Temporal Sulcus for Auditory Categorization

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    The affinity and temporal course of functional fields in middle and posterior superior temporal cortex for the categorization of complex sounds was examined using functional magnetic resonance imaging (fMRI) and event-related potentials (ERPs) recorded simultaneously. Data were compared before and after subjects were trained to categorize a continuum of unfamiliar nonphonemic auditory patterns with speech-like properties (NP) and a continuum of familiar phonemic patterns (P). fMRI activation for NP increased after training in left posterior superior temporal sulcus (pSTS). The ERP P2 response to NP also increased with training, and its scalp topography was consistent with left posterior superior temporal generators. In contrast, the left middle superior temporal sulcus (mSTS) showed fMRI activation only for P, and this response was not affected by training. The P2 response to P was also independent of training, and its estimated source was more anterior in left superior temporal cortex. Results are consistent with a role for left pSTS in short-term representation of relevant sound features that provide the basis for identifying newly acquired sound categories. Categorization of highly familiar phonemic patterns is mediated by long-term representations in left mSTS. Results provide new insight regarding the function of ventral and dorsal auditory streams

    Efficiency of shrimp trawl nets polyamide and polyethylene with standard mesh in the coastal waters of Bushehr Province

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    This study was carried out in August – september 2009 in Bushehr province waters. Two different shrimp bottom trawls were used in which were woven by Poly Amid and Poly Ethylene with mesh sizes (stretched) of 50 mm and sack with 35 mm. Also 2 different vessels of two dhows and one steel ship each with 26 and 30 hauls were used and taken in to comparison from point of obtained results. Total catch of PA and PE trawels were 4592 and 5535 kg of which the ratio of shrimp catch and by catch for PA trawl was 32.4 and 67.6 % respectively; and for PE trawl was 34.2 and 65.8%. Total catch of PA and PE trawls of steel trawler ( ship ) were estimated 3158.0 and 4784.7 kg, respectively, of which the shrimp/ bycatch ratio was 6.6 : 93.4%. There was a higher amount of bycatch for PE comparing to PA trawl (p<0.05). on the other hand the decrease of shrimp and bycatch for PA comparing to PE dhow trawlers were 21.3 and 15.0% and for ship were 34.6 and 34.0% respectively. The weight ratio is 1:15 i.e . in PE ship trawl, in proportion to on kg shrimp, 15 kg bycatch was harvested. it is proposed to standardize the mesh size and also to do obligtory the instal of squared mesh size panel

    PET and MRI for the evaluation of regional myocardial perfusion and wall thickening after myocardial infarction

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    Deterioration of left ventricular (LV) function after myocardial infarction (MI) is a major cause of heart failure. Myocardial perfusion performance may play an important role in deterioration or improvement in LV function after MI. The aim of this study was to evaluate the myocardial perfusion reserve (MPR) and stress perfusion in deteriorating and non-deteriorating LV segments in patients after MI by PET and MRI, respectively. Regional wall thickening of 352 segments in 22 patients was assessed at 4 and 24 months after MI by cardiac MRI. PET was performed to evaluate MPR and adenosine stress N-13-ammonia perfusion 24 months after MI. Segments were divided into four groups according to deterioration or improvement in wall thickening. Normal functional segments at 4 months after MI that remained stable had a significantly higher mean MPR and mean stress perfusion PET value than deteriorated segments (p < 0.001). Furthermore, dysfunctional segments that improved had a significantly higher mean stress perfusion PET value than dysfunctional segments that remained dysfunctional (p < 0.001). This study demonstrated the additional value of myocardial perfusion assessment in relation to the functional integrity of the injured myocardium. Segmental functional LV improvement after MI was associated with better regional myocardial perfusion characteristics. Furthermore, the amount of wall thickening reduction was associated with regional myocardial perfusion abnormalities in patients after MI

    Topology-aware Quality-of-Service Support in Highly Integrated Chip Multiprocessors

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    Current design complexity trends, poor wire scalability, and power limitations argue in favor of highly modular onchip systems. Today’s state-of-the-art CMPs already feature up to a hundred discrete cores. With increasing levels of integration, CMPs with hundreds of cores, cache tiles, and specialized accelerators are anticipated in the near future. Meanwhile, server consolidation and cloud computing paradigms have emerged as profit vehicles for exploiting abundant resources of chip-multiprocessors. As multiple, potentially malevolent, users begin to share virtualized resources of a single chip, CMP-level quality-of-service (QOS) support becomes necessary to provide performance isolation, service guarantees, and security. This work takes a topology-aware approach to on-chip QOS. We propose to segregate shared resources, such as memory controllers and accelerators, into dedicated islands (shared regions) of the chip with full hardware QOS support. We rely on a richly connected Multidrop Express Channel (MECS) topology to connect individual nodes to shared regions, foregoing QOS support in much of the substrate and eliminating its respective overheads. We evaluate several topologies for the QOSenabled shared regions, focusing on the interaction between network-on-chip (NOC) and QOS metrics. We explore a new topology called Destination Partitioned Subnets (DPS), which uses a light-weight dedicated network for each destination node. On synthetic workloads, DPS nearly matches or outperforms other topologies with comparable bisection bandwidth in terms of performance, area overhead, energyefficiency, fairness, and preemption resilience.

    Carotid Plaque Imaging with SPECT/CT and PET/CT

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    A major contributor to the occurrence of ischemic stroke is the existence of carotid atherosclerosis. A vulnerable carotid atherosclerotic plaque may rupture or erode, thus causing a thrombotic event. Currently, clinical decision-making with regard to carotid endarterectomy or stenting is still primarily based on the extent of luminal stenosis, estimated with CT angiography and/or (duplex) ultrasonography. However, there is growing evidence that the anatomic impact of stenosis alone has limited value in predicting the exact consequences of plaque vulnerability. Various molecular processes have, independently of degree of stenosis, shown to be importantly associated with the plaque's capability to cause thrombotic events. These molecular processes can be visualized with nuclear medicine techniques allowing the identification of vulnerable patients by non-invasive in vivo SPECT(/CT) and PET(/CT) imaging. This chapter provides an overview of SPECT(/CT) and PET(/CT) imaging with specific radiotracers that have been evaluated for the detection of plaques together with a future perspective in this field of imaging.</p

    FcRn Overexpression in Transgenic Mice Results in Augmented APC Activity and Robust Immune Response with Increased Diversity of Induced Antibodies

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    Our previous studies have shown that overexpression of bovine FcRn (bFcRn) in transgenic (Tg) mice leads to an increase in the humoral immune response, characterized by larger numbers of Ag-specific B cells and other immune cells in secondary lymphoid organs and higher levels of circulating Ag-specific antibodies (Abs). To gain additional insights into the mechanisms underlying this increase in humoral immune response, we further characterized the bFcRn Tg mice. Our Western blot analysis showed strong expression of the bFcRn transgene in peritoneal macrophages and bone marrow derived dendritic cells; and a quantitative PCR analysis demonstrated that the expression ratios of the bFcRn to mFcRn were 2.6- and 10-fold in these cells, respectively. We also found that overexpression of bFcRn enhances the phagocytosis of Ag-IgG immune complexes (ICs) by both macrophages and dendritic cells and significantly improves Ag presentation by dendritic cells. Finally, we determined that immunized bFcRn mice produce a much greater diversity of Ag-specific IgM, whereas only the levels, but not the diversity, of IgG is increased by overexpression of bFcRn. We suggest that the increase in diversity of IgG in Tg mice is prevented by a selective bias towards immunodominant epitopes of ovalbumin, which was used in this study as a model antigen. These results are also in line with our previous reports describing a substantial increase in the levels of Ag-specific IgG in FcRn Tg mice immunized with Ags that are weakly immunogenic and, therefore, not affected by immunodominance

    Rheological, physicochemical, and microstructural properties of asphalt binder modified by fumed silica nanoparticles

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    Warm mix asphalt (WMA) is gaining increased attention in the asphalt paving industry as an eco-friendly and sustainable technology. WMA technologies are favorable in producing asphalt mixtures at temperatures 20–60 °C lower in comparison to conventional hot mix asphalt. This saves non-renewable fossil fuels, reduces energy consumption, and minimizes vapors and greenhouse gas emissions in the production, placement and conservation processes of asphalt mixtures. At the same time, this temperature reduction must not reduce the performance of asphalt pavements in-field. Low aging resistance, high moisture susceptibility, and low durability are generally seen as substantial drawbacks of WMA, which can lead to inferior pavement performance, and increased maintenance costs. This is partly due to the fact that low production temperature may increase the amount of water molecules trapped in the asphalt mixture. As a potential remedy, here we use fumed silica nanoparticles (FSN) have shown excellent potential in enhancing moisture and aging susceptibility of asphalt binders. In this study, asphalt binder modification by means of FSN was investigated, considering the effects of short-term and long-term aging on the rheological, thermal, and microstructural binder properties. This research paves the way for optimizing WMA by nanoparticles to present enhanced green asphalt technology
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