bluuebunny/crossref_metadata_2025_split huggingface dataset:
Decomposing Components of Task Preparation with Functional Magnetic Resonance Imaging
Authors: Brass Marcel , Cramon D. Yves von 
Published: May 2004

Abstract
It is widely acknowledged that the prefrontal cortex plays a major role in cognitive control processes. One important experimental paradigm for investigating such higher order cognitive control is the task-switching paradigm. This paradigm investigates the ability to switch flexibly between different task situations. In this context, it has been found that participants are able to anticipatorily prepare an upcoming task. This ability has been assumed to reflect endogenous cognitive control. However, it is difficult to isolate task preparation process from task execution using functional magnetic resonance imaging (fMRI). In the present study, we introduce a new experimental manipulation to investigate task preparation with fMRI. By manipulating the number of times a task was prepared, we could demonstrate that the left inferior frontal junction (IFJ) area (near the junction of inferior frontal sulcus and inferior precentral sulcus), the right inferior frontal gyrus, and the right intraparietal sulcus are involved in task preparation. By manipulating the cue-task mapping, we could further show that this activation is not related to cue encoding but to the updating of the relevant task representation. Based on these and previous results, we assume that the IFJ area constitutes a functionally separable division of the lateral prefrontal cortex. Finally, our data suggest that task preparation does not differ for switch and repetition trials in paradigms with a high proportion of switch trials, casting doubt on the assumption that an independent task set reconfiguration process takes place in the preparation interval.
The Relationship of Three Cortical Regions to an Information-Processing Model
Authors: Anderson John R. , Qin Yulin , Stenger V. Andrew , Carter Cameron S. 
Published: May 2004

Abstract
This research tests a model of the computational role of three cortical regions in tasks like algebra equation solving. The model assumes that there is a left parietal region-of-interest (ROI) where the problem expression is represented and transformed, a left prefrontal ROI where information for solving the task is retrieved, and a motor ROI where hand movements to produce the answer are programmed. A functional magnetic resonance imaging (fMRI) study of an abstract symbolmanipulation task was performed to articulate the roles of these three regions. Participants learned to associate words with instructions for transforming strings of letters. The study manipulated the need to retrieve these instructions, the need to transform the strings, and whether there was a delay between calculation of the answer and the output of the answer. As predicted, the left parietal ROI mainly reflected the need for a transformation and the left prefrontal ROI the need for retrieval. Homologous right ROIs showed similar but weaker responses. Neither the prefrontal nor the parietal ROIs responded to delay, but the motor ROI did respond to delay, implying motor rehearsal over the delay. Except for the motor ROI, these patterns of activity did not vary with response hand. In an ACT-R model, it was shown that the activity of an imaginal buffer predicted the blood oxygen level-dependent (BOLD) response of the parietal ROI, the activity of a retrieval buffer predicted the response of the prefrontal ROI, and the activity of a manual buffer predicted the response of the motor ROI.
The Hippocampal System Mediates Logical Reasoning about Familiar Spatial Environments
Authors: Goel Vinod , Makale Milan , Grafman Jordan 
Published: May 2004

Abstract
It has recently been shown that syllogistic reasoning engages two dissociable neural systems. Reasoning about familiar situations engages a frontal-temporal lobe system, whereas formally identical reasoning tasks involving unfamiliar situations recruit a frontal-parietal visuospatial network. These two systems may correspond to the “heuristic” and “formal” methods, respectively, postulated by cognitive theory. To determine if this dissociation generalizes to reasoning about transitive spatial relations, we studied 14 volunteers using event-related fMRI, as they reasoned about landmarks in familiar and unfamiliar environments. Our main finding is a task (reasoning and baseline) by spatial content (familiar and unfamiliar) interaction. Modulation of reasoning toward unfamiliar landmarks resulted in bilateral activation of superior and inferior parietal lobules (BA 7, 40), dorsal superior frontal cortex (BA 6), and right superior and middle frontal gyri (BA 8), regions widely implicated in visuospatial processing. By contrast, modulation of the reasoning task toward familiar landmarks, engaged the right inferior/orbital frontal gyrus (BA 11/47), bilateral occipital (BA 18, 19), and temporal lobes. The temporal lobe activation included the right inferior temporal gyrus (BA 37), posterior hippocampus, and parahippocampal gyrus, regions implicated in spatial memory and navigation tasks. These results provide support for the generalization of dual mechanism theory to transitive reasoning and highlight the importance of the hippocampal system in reasoning about familiar spatial environments.
Attention to 3-D Shape, 3-D Motion, and Texture in 3-D Structure from Motion Displays
Authors: Peuskens Hendrik , Claeys Kristl G. , Todd James T. , Norman J. Farley , Hecke Paul Van , Orban Guy A. 
Published: May 2004

Abstract
We used fMRI to directly compare the neural substrates of three-dimensional (3-D) shape and motion processing for realistic textured objects rotating in depth. Subjects made judgments about several different attributes of these objects, including 3-D shape, the 3-D motion, and the scale of surface texture. For all of these tasks, we equated visual input, motor output, and task difficulty, and we controlled for differences in spatial attention. Judgments about 3-D shape from motion involve both parietal and occipito-temporal regions. The processing of 3-D shape is associated with the analysis of 3-D motion in parietal regions and the analysis of surface texture in occipito-temporal regions, which is consistent with the different behavioral roles that are typically attributed to the dorsal and ventral processing streams.
“What” and “Where” in Visual Working Memory: A Computational Neurodynamical Perspective for Integrating fMRI and Single-Neuron Data
Authors: Deco Gustavo , Rolls Edmund T. , Horwitz Barry 
Published: May 2004

AbstractSingle-neuron recordings, functional magnetic resonance imaging (fMRI) data, and the effects of lesions indicate that the prefrontal cortex (PFC) is involved in some types of working memory and related cognitive processes. Based on these data, two different models of the topographical and functional organization of the PFC have been proposed: organization-by-stimulus-domain, and organization-by-process. In this article, we utilize an integrate-and-fire network to model both single-neuron and fMRI data on short-term memory in order to understand data obtained in topologically different parts of the PFC during working memory tasks. We explicitly model the mechanisms that underlie workingmemory-related activity during the execution of delay tasks that have a “what”-then-“where” design (with both object and spatial delayed responses within the same trial). The model contains different populations of neurons (as found experimentally) in attractor networks that respond in the delay period to the stimulus object, the stimulus position, and to combinations of both object and position information. The pools are arranged hierarchically and have global inhibition through inhibitory interneurons to implement competition. It is shown that a biasing attentional input to define the current relevant information (object or location) enables the system to select the correct neuronal populations during the delay period in what is a biased competition model of attention. The processes occurring at the AMPA and NMDA synapses are dynamically modeled in the integrate-and-fire implementation to produce realistic spiking dynamics. It is shown that the fMRI data characteristic of the dorsal PFC and linked to spatial processing and manipulation of items can be reproduced in the model by a high level of inhibition, whereas the fMRI data characteristic of the ventral PFC and linked to object processing can be produced by a lower level of inhibition, even though the network is itself topographically homogeneous with no spatial topology of the neurons. This article, thus, not only presents a model for how spatial versus object short-term memory could be implemented in the PFC, but also shows that the fMRI BOLD signal measured during such tasks from different parts of the PFC could reflect a higher level of inhibition dorsally, without this dorsal region necessarily being primarily spatial and the ventral region object-related.
An fMRI Study of Syntactic Adaptation
Authors: Noppeney U. , Price C. J. 
Published: May 2004

Abstract
It is easier to produce and comprehend a series of sentences when they have similar syntactic structures. This “syntactic priming” effect was investigated during silent sentence reading using (i) blood oxygenation level-dependent (BOLD) response as a physiological measure in an f MRI study and (ii) reading time as a behavioral measure in a complementary selfpaced reading paradigm. We found that reading time and left anterior temporal activation were decreased when subjects read sentences with similar relative to dissimilar syntactic forms. Thus, syntactic adaptation during sentence comprehension is demonstrated in a neural area that has previously been linked to both lexical semantic and sentence processing.
A Classification Paradigm for Distributed Vertically Partitioned Data
Authors: Basak Jayanta , Kothari Ravi 
Published: May 2004

In general, pattern classification algorithms assume that all the features are available during the construction of a classifier and its subsequent use. In many practical situations, data are recorded in different servers that are geographically apart, and each server observes features of local interest. The underlying infrastructure and other logistics (such as access control) in many cases do not permit continual synchronization. Each server thus has a partial view of the data in the sense that feature subsets (not necessarily disjoint) are available at each server. In this article, we present a classification algorithm for this distributed vertically partitioned data. We assume that local classifiers can be constructed based on the local partial views of the data available at each server. These local classifiers can be any one of the many standard classifiers (e.g., neuralnetworks, decision tree, k nearest neighbor). Often these local classifiers are constructed to support decision making at each location, and our focus is not on these individual local classifiers. Rather, our focus is constructing a classifier that can use these local classifiers to achieve an error rate that is as close as possible to that of a classifier having access to the entire feature set. We empirically demonstrate the efficacy of the proposed algorithm and also provide theoretical results quantifying the loss that results as compared to the situation where the entire feature set is available to any single classifier.
A Product‐Nonspecific Framework for Evaluating the Potential of Biomass‐Based Products to Displace Fossil Fuels
Authors: Lynd Lee R. , Wang Michael Q. 
Published: May 2004

SummaryThe use of biomass as a raw material for production of fuels and commodity chemicals is attracting increasing attention motivated by the possibility of positive contributions to a sustainable resource supply, enhanced national security, and macroeconomic benefits for rural communities and society at large. Fossil fuel displacement exclusive of product recovery can be estimated for biological processing of biomass in the absence of product‐specific information other than the product yield and whether fermentation is aerobic or anaerobic. Based on this observation, a framework is proposed for estimating fossil fuel displacement on a per‐unit‐product or per‐unit‐biomass basis. Use of a per‐unit‐biomass basis offers somewhat different insights as compared to a per‐unit‐product basis and appears particularly appropriate for consideration of the efficacy of resource or land use. Using the proposed framework, the following feedstock and process factors are shown to be particularly important in determining the extent of fossil fuel displacement via biological processes: feedstock (corn or cellulosic) and, for corn, harvest mode (e.g., with or without stover recovery); biological conversion (aerobic or anaerobic); product yield; and the energy requirements for product recovery. When all of these factors are favorable, as in the case of the cellulosic ethanol scenario examined, significant fossil fuel displacement can be achieved. When all of these factors are unfavorable, as in the case of a scenario involving polyhydroxyalkanoate (PHA) production from corn without stover recovery, no net displacement is achieved. The proposed framework provides a means to screen processes with respect to potential for fossil fuel displacement in the absence of product‐specific information, to gain general insights into feedstock and process features important in determining the extent to which fossil displacement is realized, and to rapidly incorporate product‐specific information into a preexisting evaluative rubric.
Surfactants Based on Renewable Raw Materials
Authors: Patel Martin 
Published: May 2004

SummaryUnder the European Commission's European Climate Change Programme, a group of experts studied the possibilities of using more renewable raw materials as chemical feedstock and assessed the related potential for greenhouse gas (GHG) emission reduction. Surfactants were among the products studied. Surfactants are currently produced from both petro‐chemical feedstocks and renewable resources (oleochemical surfactants). Assuming, in a first step, that total surfactant production in the European Union remains constant until 2010, it was estimated that the amount of oleochemical surfactants could be increased from about 880 kilotons (kt) in 1998 to approximately 1, 100 kt in 2010 (an increase of 24%). This substitution reduces the life‐cycle CO2emissions from surfactants by 8%; the theoretical maximum potential for total substitution is 37%. Because the surfactant market is expected to grow, the avoided emissions will probably exceed 8% of the current life‐cycle CO2emissions from surfactants. If compared to the CO2emissions from the total industrial sector and, even more so, if compared to the total economy, the relative savings are much lower (0.02% to 0.09%). This leads to the conclusion that the increased production and use of biobased surfactants should be part of an overall GHG emission reduction strategy consisting of a whole range of measures addressing both energy demand and supply. This article also discusses policies and measures designed to increase the use of biobased surfactants.
Making Plastics from Garbage
Authors: Sakai Kenji , Taniguchi Masayuki , Miura Shigenobu , Ohara Hitomi , Matsumoto Toru , Shirai Yoshihito 
Published: May 2004

SummaryWe propose a novel recycling system for municipal food waste that combines fermentation and chemical processes to produce high‐quality poly‐L‐lactate (PLLA) biodegradable plastics. The process consists of removal of endogenous D, L‐lactic acid from minced food waste by a propionibacterium, L‐lactic acid fermentation under semisolid conditions, L‐lactic acid purification via butyl esterification, and L‐lactic acid polymerization via LL‐lactide. The total design of the process enables a high yield of PLLA with high optical activity (i.e., a high proportion of optical isomers) and novel recycling of all materials produced at each step, with energy savings and minimal emissions. Approximately 50% of the total carbon was removed, mostly as L‐lactic acid, and 100 kg of collected food waste yielded 7.0 kg PLLA (about 34% of the total carbon). The physical properties of the PLLA yielded in this manner were comparable to those of PLLA generated from commercially available. L‐lactic acid. Evaluation of the process is also discussed from the viewpoints of material and energy balances and environmental impact.
Using Life‐Cycle Assessment in Process Design
Authors: Gasafi Edgar , Meyer Lutz , Schebek Liselotte 
Published: May 2004

SummaryThis article presents the application of life‐cycle assessment in early phases of process design in the context of technology that employs a bio‐based material. The goal is to identify hot spots in the process chains with regard to environmental impacts by performing a dominance analysis. By focusing his activities on the hot spots identified, the designer is given the opportunity to efficiently improve environmental performance. This approach is illustrated for the case of supercritical water gasification, a novel technology for the treatment of organic feedstock with high moisture content. In the reactor under supercritical conditions, organic components are converted into a high‐caloric synthesis gas, with hydrogen, methane, and carbon dioxide as the main products. The data used for the assessment are obtained from laboratory tests and the literature, completed by assumptions for missing data. The scope of assessment ranges from the extraction of raw materials to the product, that is, hydrogen (cradle to gate) with sewage sludge of a municipal wastewater treatment plant used as feedstock. The assessment identifies the main sources of environmental impacts. The predominant process step in terms of global warming potential is the supply of the gasification process with additional heat. The production of a blending agent in the dewatering step is the main source of the impact category of acidification, whereas the wastewater treatment plant is the origin of emissions that lead to eutrophication. The revealed sources are analyzed further and options for reducing the environmental impacts are discussed.
Energy and Environmental Aspects of Using Corn Stover for Fuel Ethanol
Authors: Sheehan John , Aden Andy , Paustian Keith , Killian Kendrick , Brenner John , Walsh Marie , Nelson Richard 
Published: May 2004

SummaryCorn stover is the residue that is left behind after corn grain harvest. We have constructed a life‐cycle model that describes collecting corn stover in the state of Iowa, in the Midwest of the United States, for the production and use of a fuel mixture consisting of 85% ethanol/15% gasoline (known as “E85”) in a flexible‐fuel light‐duty vehicle. The model incorporates results from individual models for soil carbon dynamics, soil erosion, agronomics of stover collection and transport, and biocon‐version of stover to ethanol.Limitations in available data forced us to focus on a scenario that assumes all farmers in the state of Iowa switch from their current cropping and tilling practices to continuous production of corn and “no‐till” practices. Under these conditions, which maximize the amount of collectible stover, Iowa alone could produce almost 8 billion liters per year of pure stover‐derived ethanol (E100) at prices competitive with today's corn‐starch‐derived fuel ethanol. Soil organic matter, an important indicator of soil health, drops slightly in the early years of stover collection but remains stable over the 90‐year time frame studied. Soil erosion is controlled at levels within tolerable soil‐loss limits established for each county in Iowa by the U.S. Department of Agriculture.We find that, for each kilometer fueled by the ethanol portion of E85, the vehicle uses 95% less petroleum compared to a kilometer driven in the same vehicle on gasoline. Total fossil energy use (coal, oil, and natural gas) and greenhouse gas emissions (fossil CO2, N2O, and CH4) on a life‐cycle basis are 102% and 113% lower, respectively. Air quality impacts are mixed, with emissions of CO, NOx, and SOx increasing, whereas hydrocarbon ozone precursors are reduced.This model can serve as a platform for future discussion and analysis of possible scenarios for the sustainable production of transportation fuels from corn stover and other agricultural residues.
Cumulative Energy and Global Warming Impact from the Production of Biomass for Biobased Products
Authors: Kim Seungdo , Dale Bruce E. 
Published: May 2004

SummaryThe cumulative energy and global warming impacts associated with producing corn, soybeans, alfalfa, and switchgrass and transporting these crops to a central crop processing facility (called a “biorefinery”) are estimated. The agricultural inputs for each crop are collected from seven states in the United States: Illinois, Indiana, Iowa, Michigan, Minnesota, Ohio, and Wisconsin. The cumulative energy requirement for producing and transporting these crops is 1.99 to 2.66 megajoules/kilo‐gram (MJ/kg) for corn, 1.98 to 2.04 MJ/kg for soybeans, 1.24 MJ/kg for alfalfa, and 0.97 to 1.34 MJ/kg for switchgrass. The global warming impact associated with producing biomass is 246 to 286 grams (g) CO2 equivalent/kg for corn, 159 to 163gCO2 equivalent/kg for soybeans, 89 g CO2 equivalent/ kg for alfalfa, and 124 to 147 g CO2 equivalent/kg for switch‐grass. The detailed agricultural data are used to assess previous controversies over the energy balance of bioethanol and, in light of the ongoing debates on this topic, provide a needed foundation for future life‐cycle assessments.
U.S. Federal Initiatives to Support Biomass Research and Development
Authors: Duncan Marvin 
Published: May 2004

SummaryThis article provides a brief overview of federal initiatives in the United States to support biomass research, demonstration, and development. The interest in the biomass industry and U.S. federal efforts to spur development of, increased production of, and use of biopower, biofuels, and biobased products, collectively known as the “biomass industry”, are discussed. A growing level of leadership from the executive branch of the federal government and support by the U.S. Congress are documented. Five important policy drivers that support this heightened emphasis on biomass for power, fuels, and products are identified and discussed. The current status of U.S. dependence on these renewable energy sources is briefly outlined. Federal biomass funding activity for the current fiscal year by the U.S. Department of Agriculture and the U.S. Department of Energy, two major federal participants in research, demonstration, and development for this industry, is briefly outlined. This funding commitment is placed into an overall context of total federal support for all research and development. Finally, the article suggests future market penetration targets for this industry, emphasizes the importance of infrastructure development necessary to support the industry's growth, and notes the payoff from such development for farmers, foresters, rural communities, and the environment.