bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variability of the paracingulate sulcus and morphometry of the medial frontal cortex: Associations with cortical thickness, surface area, volume, and sulcal depth
Authors: Fornito Alex , Wood Stephen J. , Whittle Sarah , Fuller Jack , Adamson Chris , Saling Michael M. , Velakoulis Dennis , Pantelis Christos , Yücel Murat 
Published: May 2007

AbstractThe structural and functional consequences of interindividual variations in cortical morphology are poorly understood. In this study, we examined the relationship between one well‐characterized variation of the medial frontal lobes, variability of the paracingulate sulcus (PCS), and grey matter volume, cortical thickness, surface area, and sulcal depth of the adjacent anterior cingulate cortex (ACC) and paracingulate cortex (PaC). Seventy‐seven healthy individuals were assigned to one of four groups depending on PCS incidence in both hemispheres: left‐present, right‐absent; left‐absent, right‐present; both absent; or both present. Comparing these groups on each measure yielded four primary findings: (1) The presence of a PCS was associated with increased PaC and decreased ACC grey matter volume in the hemisphere in which it was apparent, with an almost identical pattern being observed for surface area; (2) there was a more complex relationship between PCS variability and regional thickness, such that a PCS in the left hemisphere was associated with increased left PaC and right ACC thickness, with no comparable effects being observed for the presence of a right PCS; (3) the depths of all major left hemisphere sulci in the region were strongly positively correlated, whereas no such associations were apparent in the right hemisphere; and (4) a leftward asymmetry in PaC thickness was specifically associated with better performance on a test of spatial working memory ability. These results provide evidence for a complex interhemispheric relationship between sulcal variability and cortical morphometry, and indicate that such relationships may be important for understanding individual differences in cognitive abilities. Hum Brain Mapp, 2008. © 2007 Wiley‐Liss, Inc.
Cross‐cultural music phrase processing: An fMRI study
Authors: Nan Yun , Knösche Thomas R. , Zysset Stefan , Friederici Angela D. 
Published: May 2007

AbstractThe current study used functional magnetic resonance imaging (fMRI) to investigate the neural basis of musical phrase boundary processing during the perception of music from native and non‐native cultures. German musicians performed a cultural categorization task while listening to phrased Western (native) and Chinese (non‐native) musical excerpts as well as modified versions of these, where the impression of phrasing has been reduced by removing the phrase boundary marking pause (henceforth called “unphrased”). Bilateral planum temporale was found to be associated with an increased difficulty of identifying phrase boundaries in unphrased Western melodies. A network involving frontal and parietal regions showed increased activation for the phrased condition with the orbital part of left inferior frontal gyrus presumably reflecting working memory aspects of the temporal integration between phrases, and the middle frontal gyrus and intraparietal sulcus probably reflecting attention processes. Areas more active in the culturally familiar, native (Western) condition included, in addition to the left planum temporale and right ventro‐medial prefrontal cortex, mainly the bilateral motor regions. These latter results are interpreted in light of sensorimotor integration. Regions with increased signal for the unfamiliar, non‐native music style (Chinese) included a right lateralized network of angular gyrus and the middle frontal gyrus, possibly reflecting higher demands on attention systems, and the right posterior insula suggesting higher loads on basic auditory processing. Hum Brain Mapp, 2008. © 2007 Wiley‐Liss, Inc.
Teaching and hospital production: The use of regression estimates
Authors: Lehner Laura A. , Burgess James F. 
Published: May 2007

AbstractMedicare's Prospective Payment System pays U.S. teaching hospitals for the indirect costs of medical education based on a regression coefficient in a cost function. In regression studies using health care data, it is common for explanatory variables to be measured imperfectly, yet the potential for measurement error is often ignored. In this paper, U.S. Department of Veterans Affairs data is used to examine issues of health care production estimation and the use of regression estimates like the teaching adjustment factor. The findings show that measurement error and persistent multicollinearity confound attempts to have a large degree of confidence in the precise magnitude of parameter estimates.
Health care reform : Motivation for discrimination?
Authors: Navin John C. , Pettit Mary Anne 
Published: May 2007

AbstractOne of the major issues in the health care reform debate is the requirement that employers pay a portion of their employees' health insurance premiums. This paper examines the method for calculating the employer share of the health care premiums, as specified in the President's health care reform proposal. The calculation of the firm's cost of providing employee health care benefits is a function of marital status as well as the incidence of two‐income earner households. This paper demonstrates that this method provides for lower than average premiums for married employees with no dependents in communities in which there is at least one married couple where both individuals participate in the labor market. This raises the non‐wage labor costs of employing single individuals relative to individuals which are identical in every respect except their marital status. This paper explores the economic implications for hiring, as well as profits, for firms located in a perfectly‐competitive industry. The results of the theoretical model presented here are clear. Under this proposed version of health care reform, ceteris paribus, firms have a clear preference for two‐earner households. This paper also demonstrates that the incentive to discriminate is related to the size of the firm and to the size of the average wage of full‐time employees for firms which employ fewer than fifty individuals. While this paper examines the specifics of President Clinton's original proposal, the conclusions reached here would apply to any form of employer‐mandated coverage in which the premiums are a function of family status and the incidence of two‐earner households.
A comparison of alternative models of prescription drug utilization
Authors: Grootendorst Paul V. 
Published: May 2007

AbstractThe two‐part estimation technique has been advocated for estimating models using individual level health care utilization data characterised by a large proportion of non‐consumption and small proportions of heavy users. This paper compares the two‐part model to several other estimators, including the Poisson, negative binomial and 'zero altered' negative binomial models on the basis of within‐sample forecasting accuracy and non‐nested model selection tests. The empirical model estimates the differential effect of the removal of copayments for prescription medicines on the prescription drug utilization by older adults with differing levels of health status. The two‐part estimator of this model is found to dominate the competitors. Results from this model indicate that utilization increases appear to be higher among individuals with lower levels of health status.
Design and evaluation of an augmented reality welding helmet
Authors: Park M. , Schmidt L. , Schlick C. , Luczak H. 
Published: May 2007

AbstractThe article describes the development and ergonomic evaluation of an augmented reality (AR) welding helmet. The system provides an augmented user interface with supporting information relevant to the welding process. The experimental studies focused on hand–eye coordination of welders and nonwelders with two prototypes of the augmented reality welding helmet. The first prototype operated at 16 frames per second, whereas the second, improved version had 20 frames per second. In addition, the hand–eye coordination while wearing the welding helmet with video see‐through head‐mounted display was compared to a performance with natural vision, without any helmet. Experimental results showed significant influence of helmet and occupation on hand–eye coordination. Subjective assessment revealed better rating for stereo perception for the system with the higher frame rate, whereas no significant difference in performance was found between the two frame rates. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 317–330, 2007.
Integrating ergonomics into engineering: Empirical evidence and implications for the ergonomists
Authors: Broberg Ole 
Published: May 2007

AbstractEngineering design is a strong determinant of workplace ergonomics. A survey among 680 engineers in 20 Danish enterprises indicated that engineers are not aware that they influence the work environment of other people. Ergonomics had a low rating among engineers, perhaps because neither management nor safety organizations expressed any expectations in this area. The study further indicated that effects of ergonomics training in engineering schools were very limited. The engineering cultures in enterprises, together with other organizational factors, are suggested to be of greater importance than the professional training. The implications for industrial ergonomists might be an acknowledgement of the role as change agent when trying to integrate ergonomics into engineering. In doing so, they need also to acknowledge that engineers are widely different. They have different backgrounds and a “sensitivity” to ergonomics depending on their current engineering domain, tasks, organizational position, and the industrial branch of their organization. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 353–366, 2007.
Modeling of water absorption induced cracks in resin‐based composite supported ceramic layer structures
Authors: Huang Min , Thompson V. P. , Rekow E. D. , Soboyejo W. O. 
Published: May 2007

AbstractCracking patterns in the top ceramic layers of the modeled dental multilayers with polymer foundation are observed when they are immersed in water. This article developed a model to understand this cracking mechanism. When water diffuses into the polymer foundation of dental restorations, the foundation will expand; as a result, the stress will build up in the top ceramic layer because of the bending and stretching. A finite element model based on this mechanism is built to predict the stress build‐up and the slow crack growth in the top ceramic layers during the water absorption. Our simulations show that the stress build‐up by this mechanism is high enough to cause the cracking in the top ceramic layers and the cracking patterns predicted by our model are well consistent with those observed in experiments on glass/epoxy/polymer multilayers. The model is then used to discuss the life prediction of different dental ceramics. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Alterations of human acellular tissue matrix by gamma irradiation: Histology, biomechanical property, stability, in vitro cell repopulation, and remodeling
Authors: Gouk Sok‐Siam , Lim Tit‐Meng , Teoh Swee‐Hin , Sun Wendell Q. 
Published: May 2007

AbstractAlloDerm, a processed acellular human tissue matrix, is used in a number of surgical applications for tissue repair and regeneration. In the present work, AlloDerm serves as a model system for studying gamma radiation‐induced changes in tissue structure and stability as well as the effect of such changes on the cell–matrix interactions, including cell repopulation and matrix remodeling. AlloDerm tissue matrix was treated with 2–30 kGy gamma irradiation at room temperature. Gamma irradiation reduced the swelling of tissue matrix upon rehydration and caused significant structural modifications, including collagen condensation and hole formation in collagen fibres. The tensile strength of AlloDerm increased at low gamma dose but decreased with increasing gamma dosage. The elasticity of irradiated AlloDerm was reduced significantly. Calorimetric study showed that gamma irradiation destabilized the tissue matrix, resulting in greater susceptibility to proteolytic enzyme degradation. Although gamma irradiation did not affect in vitro proliferation of fibroblast cells, it promoted tissue degradation upon cell repopulation and influenced synthesis and deposition of new collagen. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Decreased focal inflammatory response by G‐CSF may improve stroke outcome after transient middle cerebral artery occlusion in rats
Authors: Sehara Yoshihide , Hayashi Takeshi , Deguchi Kentaro , Zhang Hanzhe , Tsuchiya Atsushi , Yamashita Toru , Lukic Violeta , Nagai Makiko , Kamiya Tatsushi , Abe Koji 
Published: May 2007

AbstractRecent studies have shown that administration of granulocyte colony‐stimulating factor (G‐CSF) is neuroprotective. However, the precise mechanisms of the neuroprotective effect of G‐CSF are not entirely known. We carried out 90‐min transient middle cerebral occlusion (tMCAO) of rats. The rats were injected with vehicle or G‐CSF (50 μg/kg) immediately after reperfusion and sacrificed 8, 24, or 72 hr later. 2,3,5‐Triphenyltetrazolium chloride (TTC) staining was carried out using brain sections of 72 hr, and immunohistochemistry was carried out with those of 8, 24, and 72 hr. TTC‐staining showed a significant reduction of infarct volume in the G‐CSF‐treated group (**P < 0.01). Immunohistochemistry showed a significant decrease of the number of cells expressing tumor necrosis factor‐α (TNF‐α) at 8–72 hr, transforming growth factor‐β (TGF‐β) and inducible nitric oxide synthase (iNOS) at 24 and 72 hr after tMCAO in the peri‐ischemic area (*P < 0.05 each). Our data suggest that the suppression of inflammatory cytokines and iNOS expression may be one mechanism of neuroprotection by G‐CSF. © 2007 Wiley‐Liss, Inc.
A dynamic key management solution to access hierarchy
Authors: Zou Xukai , Karandikar Yogesh , Bertino Elisa 
Published: May 2007

AbstractHierarchical access control (HAC) has been a fundamental problem in computer and network systems. Since Akl and Taylor proposed the first HAC scheme based on number theory in 1983, cryptographic key management techniques for HAC have appeared as a new and promising class of solutions to the HAC problem. Many cryptographic HAC schemes have been proposed in the past two decades. One common feature associated with these schemes is that they basically limited dynamic operations at the node level. In this paper, by introducing the innovative concept of ‘access polynomial’ and representing a key value as the sum of two polynomials in a finite field, we propose a new key management scheme for dynamic access hierarchy. The newly proposed scheme supports full dynamics at both the node level and user level in a uniform yet efficient manner. Furthermore, the new scheme allows access hierarchy to be a random structure and can be flexibly adapted to many other access models such as ‘transfer down’ and ‘depth‐limited transfer’. Copyright © 2007 John Wiley & Sons, Ltd.
Cross‐layer design to improve elastic traffic performance in WLANs
Authors: Lohier Stephane , Doudane Yacine Ghamri , Pujolle Guy 
Published: May 2007

AbstractIn this paper, we are interested in improving TCP flow performance when a short loss of 802.11 signal leads to losing segments and triggers inappropriately TCP congestion control mechanisms. A set of measurements in a common wireless environment with signal losses due to mobility or interference is made to highlight the distinct MAC and TCP loss recovery levels and the lack of interactions between them. Initially, we demonstrate the interest of adapting the 802.11 MAC layer Retry Limit parameter in the case of signal losses due to distance or obstacles (mobility). Thus, a first‐level loss differentiation algorithm (LDA) acting at the MAC layer is proposed to improve TCP flow performance in the case of segment losses due to mobility. Hence, for a signal failure, the MAC layer reacts consequently by dynamically adapting the Retry Limit parameter. This adaptation allows avoiding a costly end‐to‐end TCP loss recovery. Segment losses due to interference are differentiated from those due to congestion through the use of a second‐level LDA. The latter is a cross‐layer LDA acting at the TCP layer but using a specific 802.11 parameter, the AckFailureCount, to realize the targeted loss differentiation. The TCP NewReno version is then adapted in order to integrate the cross‐layer LDA results and to avoid reducing the TCP congestion window unsuitably. The efficiency and completeness of a solution integrating both LDA schemes is then discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Network models for maximization of heat transfer under weight constraints
Authors: Bhargav S. , Duffin R. J. 
Published: May 2007

AbstractOf concern is a network in which the conductance of certain branches are variable. The problem posed is the maximization of the joint conductance subject to a bound on the lρ norm of the variable conductances. It is shown that at an optimum state the conductance of a variable branch is proportional to the 2/(ρ+1) power of the current through the branch. This relation together with a dual variational principle leads to a “duality inequality” giving sharp upper and lower estimates of the maximum joint conductance. Such a network serves as a discrete model for a cooling fin subject to a weight limitation. Thus the model shows what analogous properties should hold for the cooling fin.
Lower bounds on the vulnerability of a graph
Authors: Boesch F. T. 
Published: May 2007

AbstractIt is well known that the size of the smallest node‐cut (connectivity‐ω) and the size of the smallest edge‐cut (cohesion‐λ) can be used as vulnerability measures of a graph. Algorithms for finding ω and λ involve the determination of many paths and therefore require a fair amount of computation. However, it is clear that, if a graph has “relatively large” degrees, then ω and λ cannot be “too small”. Furthermore, the degrees of the nodes are a most readily available set of parameters for any graph. Hence, any lower bounds based on the degrees is extremely valuable.Prior results on these types of bounds are collected here. A few new results are also derived. In all cases the bounds are quite simple and can easily be obtained by hand calculations for extremely large graphs.
On the design of reliable networks
Authors: Hakimi S. L. , Amin A. T. 
Published: May 2007

AbstractThis paper is concerned with construction of graphs, with n vertices and m edges, whose connectivity r = [2m/n] ≧ 3, and have no more than n minimum vertex cut‐sets. Frank's results imply that this is an important step in the design of a class of reliable networks.
On operating a shuttle service
Authors: Barnett A. 
Published: May 2007

AbstractA vehicle shuttles between two terminals, at which passengers are arriving in a Poisson manner at given rates. Travel time between the stops is assumed deterministic. This paper considers the question of what operating strategy will yield lowest average waiting time for passengers of the system. Exact solutions to the problem are obtained, and it is found that the optimal strategy is a somewhat complex but very tractable function of the two Poisson arrival parameters.
Modeling and optimal control of congested transportation systems
Authors: Gazis D. C. 
Published: May 2007

AbstractAn approach is discussed for the modeling of congested transportation systems as store‐and‐forward networks analogous to communication networks of this type but with a finite travel time between nodes. A variety of approaches is suggested, and illustrated by examples, for the allocation of the usage of the arcs of the network by various competing units of traffic.
Disjoint paths in a network
Authors: Suurballe J. W. 
Published: May 2007

AbstractRoutes between two given nodes of a network are called diversified if they are node‐disjoint, except at the terminals. Diversified routes are required for reliability in communication, and an additional criterion is that their total cost, assumed to be the sum of individual arc lengths or costs, is minimum. An algorithm and related theory is described for a general number K of node‐disjoint paths with minimum total length. The algorithm applies shortest path labeling algorithms familiar in the literature. K node‐disjoint paths are found in K iterations of a single shortest path algorithm.
Computing capacitated minimal spanning trees efficiently
Authors: Kershenbaum A. 
Published: May 2007

AbstractAn analysis is made of the computational complexity of a class of heuristic algorithms for the solution of the minimal spanning tree problem subject to a restriction on the maximum number (or weight) of nodes in any subtree rooted at a distinguished node. This is of particular interest in designing networks with branch capacity restrictions. The algorithm is a modification of Kruskal's Algorithm where weights are assigned to the nodes and then used, along with the arc lengths, to select the order in which arcs are considered for inclusion in the spanning tree. Considerations in the efficient implementation of such algorithms are examined and several heuristics for assigning node weights are compared.
Hydraulic network analysis using (generalized) geometric programming
Authors: Hall M. A. 
Published: May 2007

AbstractThe problem of determining the flows (and pressures) in the pipes of a general hydraulic network, for given input and output flows and/or given input and output pressure heads, is shown to be equivalent to either of a pair of convex programming problems with linear constraints. This is accomplished via the theory of (generalized) Geometric Programming. The equivalence of these problems is exploited to prove existence and uniqueness of the flow solution under certain conditions as well as to derive an algorithm which calculates this solution. Computational aspects of implementing the algorithm are considered in some detail and results obtained for a general example problem are presented. A brief discussion of the application of the methods of the paper to problems in electrical network analysis, transportation network analysis and the elastic analysis of structural trusses, is also given.
On cost allocation for a spanning tree: A game theoretic approach
Authors: Bird C. G. 
Published: May 2007

AbstractCooperative game theory solution concepts are used to allocate costs in a spanning tree network. Stable cost allocations are related to the core of a cooperative game and it is proved that every game generated from a minimum cost spanning tree with an immovable source has a core. A refinement of the core, called the irreducible core, is introduced and the extreme points of the solution can be characterized by permutations of the minimal cost spanning tree. Points in the irreducible core are shown to be stable under unions of additional players. A weighted Shapley value is used to obtain a unique allocation of costs. This value coincides with the marginal costs of the spanning tree when there is only one minimal spanning tree. When multiple sources are allowed, counterexamples to the existence of a core are presented unless extra taxes are levied on the users.
Finding optimum branchings
Authors: Tarjan R. E. 
Published: May 2007

AbstractChu and Liu, Edmonds, and Bock have independently devised an efficient algorithm to find an optimum branching in a directed graph. We give an implementation of the algorithm which runs in 0(m logn) time if the problem graph has n vertices and m edges. A modification for dense graphs gives a running time of 0(n2). We also show that the unmodified algorithm runs in 0(n(log n)2 +m) time on an average graph, assuming a uniform probability distribution.