bluuebunny/crossref_metadata_2025 huggingface dataset:
Review: Psychological responses to injury in competitive sport: a critical review
Authors: Walker Natalie , Thatcher Joanne , Lavallee David
Published: June 2007

Research has attempted to examine the psychological impact of athletic injury to assist rehabilitation personnel when treating injured athletes. Sports trainers, sports therapists, physiotherapists, medical staff and sports psychologists should be aware of psychological factors impacting on the injury experience when involved in an athlete's rehabilitation. A number of models have been proposed as useful frameworks for investigating and describing the psychological response to athletic injury. Many researchers have relied upon applying or adapting grief and cognitive appraisal models originally derived from the clinical and stress related psychology literature in an attempt to describe the psychological response to athletic injury. This article provides an overview of these models and offers a critical appraisal of this research, specifically focusing on the grief response models and the integrated model of response to sport injury and rehabilitation. Criticisms focus on the lack of research supporting a uniformed sequence of stages as a feature of response to athletic injury. Further grief criticisms centre on the absence of denial in much of the research to date. The article then focuses on the dynamic core of the integrated response to sport injury and rehabilitation model. It is argued that the interrelationships between emotional responses, behavioural responses, cognitive appraisals and recovery outcomes are not as simple as suggested in the model.
Planning rights and their Implications
Authors: Alexander E.R.
Published: June 2007

Planning rights' (PRs) implications for planning theory and practice are traced in several directions. One explores the complex planning process, where PRs can link the micro-scale to the macro-level of theory and analysis. Another addresses the opposition between planning and property rights, which the concept of PRs resolves. For evaluation in planning, awareness of PRs implies revisions in theory and practice, balancing utilitarian-analytic with normative-dialogic approaches. Recognizing PRs also revitalizes the Public Interest. PRs have positive implications too for the meta-ethics of planning, integrating consequential-utilitarianism with value-based normative judgment. This will affect enacted planning practice and enable real application of professional ethics.
Planning rules for a self-planned city
Authors: Alfasi Nurit , Portugali Juval
Published: June 2007

Planning theory, laws, and systems are essentially procedural in that they focus on the process of planning and decision-making but do not deal with the substance of the decisions nor their impact on cities. They emphasize the role of the many (f)actors that shape the built environment rather than the resultant properties of the built environment itself. This is true both for the rational comprehensive theory of the 1960s and the 1990s postmodern theory of communicative planning theory. In this article we claim that current planning weaknesses, on the one hand, and viewing cities as complex self-organizing systems, on the other, require re-linking planning theory, law, and administration to the substantive qualitative relations between the various urban elements. We then introduce, first, an example for theorizing such an `Urban Code' that turns the spatial relations into a planning rule and, second, a suggestion for a planning system that is responsive to these qualitative relations and is capable of updating them.
Metalogue as Methodology
Authors: Staller Karen
Published: June 2007

Peer review, standard practice for most scholarly journals, often involves mundane discussions between writer and referees mediated by an editor. Occasionally invoked are more controversial issues such as the nature of science or the standards associated with good scientific practice. This article makes a case for recognizing the critical significance of this site — where exchanges between authors, editors and referees take place — as the location where boundaries of acceptable scholarship are negotiated. I argue that metalogues — written conversations among parties that preserve individual voices while revealing contested areas — offer a method of inquiry for exploring the creation of scholarship. Using referees' comments, this article explores what one contested area might look like using writing style as an example. It models the metalogue as a method of inquiry. An advantage of this practice is making visible otherwise abstract philosophical debates through applied examples using empirical evidence generated during the review process.
Endovascular Repair of Thoracic Aortic Disease: Early and Midterm Experience
Authors: Chu Michael W. A. , Forbes Thomas L. , Kirk Lawlor D. , Harris Kenneth A. , DeRose Guy
Published: June 2007

Thoracic aorta disease remains a challenging problem, and despite improvements, open repair techniques are still associated with significant morbidity and mortality. This is a retrospective review of 53 consecutive patients with thoracic aortic pathology who were treated with endovascular repair between September 1998 and December 2004 at a tertiary-care hospital. Endovascular stent graft placement was performed on 23 elective and 30 emergent patients (34 male patients, mean age 66 years, 21 to 85 years). Completion angiography revealed no endoleak in 47 (89%) patients, a type I endoleak in 4 patients, and a type II endoleak in 2 patients. Operative 30-day mortality for elective aneurysms (n = 22), emergent aneurysms (n = 10), dissection (n = 3), penetrating aortic ulcers (n = 7), and trauma (n = 11) was 0%, 40%, 0%, 29%, and 9%, respectively. In total, 46 (87%) patients survived 30 days, and 36 (78.3%) of the survivors were discharged home free of complications. Two patients (4%) experienced paraplegia. Median follow-up was 22 months (1 to 72 months). Intermediate-term results revealed 41 (89%) patients free of endoleak, stent migration, or aneurysmal expansion. Two (4%) patients required reintervention with an additional stent graft. There were 2 (4%) patients with late aortic-related deaths and four (9%) patients with non—aorticrelated late deaths. Endovascular stent graft placement for thoracic aorta disease can be performed successfully and safely with good perioperative and intermediate-term outcomes. Stent graft complication and reintervention rates are low, whereas intermediate survival rates are good. Long-term efficacy still needs to be evaluated.
Arteriography in the Delayed Evaluation of Wartime Extremity Injuries
Authors: Johnson Owen N. , Fox Charles J. , O'Donnell Sean , Weber Michael , Adams Eric , Cox Mitchell , Quan Reagan , Rich Norm , Gillespie David L.
Published: June 2007

Recent combat casualties have stimulated a reassessment of the principles of management of high-risk extremity injuries with a normal vascular examination. Rapid evacuations have presented numerous U.S. soldiers to our service for evaluation in the early postinjury period. The objective of this single-institution report is to analyze the application of liberal arteriography in the delayed evaluation of modern wartime extremity injuries. Data from consecutive wartime evacuees evaluated for extremity injuries between March 2002 and November 2004 were prospectively entered into a database and retrospectively reviewed. Analysis was focused on arteriography and its role in our current diagnostic and therapeutic approach. Information including injury sites and mechanisms, associated trauma, battlefield repairs performed, arteriography technique, complications, findings, and need for further intervention were reviewed. Indications for imaging in this high-risk group included proximity to vascular structures, abnormal or equivocal physical examination, adjunctive operative planning, and evaluation of battlefield repair. Ninety-nine of 179 patients (55%) with extremity injuries underwent arteriography, with 142 total limbs studied. The majority of them were wounded by explosive devices (82%) or high-velocity rifle munitions (14%). Abnormalities were found in 75 of 142 (52.8%) imaged limbs in 46 of the 99 (46.5%) patients. Twenty-four of these patients (52.2%) required additional operative intervention. Occult vascular injury findings were associated with bony fracture in 68% and nerve injury in 16%. Median delay between injury and stateside evaluation was 6 days. Two thirds of these soldiers presented with a normal physical examination result. There were no access site complications or incidents of contrast-induced acute renal failure. The liberal application of arteriography is a low-risk method to provide high-yield data in the delayed vascular evaluation of extremities injured from modern military munitions. Physical examination findings remain the most useful indicator, but a normal examination can be misleading and should not guide the decision for invasive imaging. Lesions are found and require further intervention at a higher rate than expected from the typical civilian trauma experience.
Preoperative Glomerular Filtration Rate and Outcome Following Open Abdominal Aortic Aneurysm Repair
Authors: Walsh Stewart R. , Tang Tjun , Sadat Umar , Varty Kevin , Boyle Jonathan R. , Gaunt Michael E.
Published: June 2007

Estimated glomerular filtration rate (eGFR) can be readily calculated from serum creatinine values. It is a more sensitive prognostic indicator than serum creatinine alone in patients undergoing thoracoabdominal or endovascular abdominal aortic aneurysm repair. The value of eGFR in patients undergoing open abdominal aortic aneurysm repair remains unclear. The preoperative eGFR was calculated for patients undergoing elective open infrarenal aortic aneurysm repair. Postoperative complications, perioperative mortality, and long-term survival were compared across eGFR and serum creatinine quartiles. The eGFR identified preoperative renal dysfunction in 33% of patients, whereas serum creatinine identified renal impairment in only 11%. The eGFR correlated with perioperative morbidity and long-term survival. Serum creatinine did not correlate with perioperative mortality or long-term survival. However, it did correlate with postoperative morbidity. The eGFR is a more sensitive index of preoperative renal function than serum creatinine and correlates with survival. It should replace serum creatinine as the standard index of renal function before open abdominal aortic aneurysm repair.
Cerebral Embolic Stroke and Arm Ischemia in a Teenager With Arterial Thoracic Outlet Syndrome: A Case Report
Authors: Lee Thomas S. , Hines George L.
Published: June 2007

A rare presentation of arterial thoracic outlet syndrome (TOS) is described in a young woman. Arterial TOS caused by a cervical rib produced acute upper extremity ischemia due to subclavian artery aneurysm formation. Clinical presentation also included left hemiparesis caused by right subclavian artery thrombosis and retrograde embolization of thrombus via the common carotid artery to the right middle cerebral artery distribution. Surgical repair of the subclavian artery was performed, but permanent neurologic deficit remained. Acute thrombosis of the right subclavian artery can produce cerebrovascular complication. The assessment of such risk in patients with arterial TOS is warranted and the arterial lesion corrected surgically.
Nursing research in Europe: a progress report
Authors: Smith Lorraine N.
Published: June 2007

This paper outlines a range of issues that currently affect nursing research in Europe with particular reference to the UK. An argument is made that nursing research needs to align itself with policy imperatives while at the same time ensuring that nursing research remains visible. The difficulty of moving between clinical and research career pathways is highlighted along with a range of problems that are seen to influence the conduct of nursing research across Europe.
Inflammation enhances consumption and presentation of transfused RBC antigens by dendritic cells
Authors: Hendrickson Jeanne E. , Chadwick Traci E. , Roback John D. , Hillyer Christopher D. , Zimring James C.
Published: June 2007

Factors regulating which patients become alloimmunized to red blood cell (RBC) antigens are poorly understood. Using a murine model of transfusion, we recently reported that viral-like inflammation with polyinosinic polycytidylic acid [poly (I:C)] significantly enhances RBC alloimmunization. Herein, we tested the hypothesis that poly (I:C) exerts this effect, at least in part, at the level of antigen-presenting cells (APCs). Using a novel in vivo method, we report that in the noninflamed state, most transfused RBCs were consumed by splenic macrophages, with only trace consumption by splenic dendritic cells (DCs). To a lesser extent, RBCs were also consumed by APCs in the liver. However, unlike soluble antigens, no RBCs were consumed by APCs in the lymph nodes. Inflammation with poly (I:C) induced significant consumption of transfused RBCs by splenic DCs, with a concomitant increase in costimulatory molecule expression. Moreover, this resulted in increased proliferation of CD4+ T cells specific for the mHEL RBC alloantigen. Finally, splenectomy abrogated the enhancing effects of poly (I:C) on RBC alloimmunization. Together, these data provide additional insight into the nature of transfused RBCs as an immunogen and provide a mechanism by which viral-like inflammation enhances alloimmunization to transfused RBCs.
ProMEX: a mass spectral reference database for proteins and protein phosphorylation sites
Authors: Hummel Jan , Niemann Michaela , Wienkoop Stefanie , Schulze Waltraud , Steinhauser Dirk , Selbig Joachim , Walther Dirk , Weckwerth Wolfram
Published: June 2007

Background

In the last decade, techniques were established for the large scale genome-wide analysis of proteins, RNA, and metabolites, and database solutions have been developed to manage the generated data sets. The Golm Metabolome Database for metabolite data (GMD) represents one such effort to make these data broadly available and to interconnect the different molecular levels of a biological system [1]. As data interpretation in the light of already existing data becomes increasingly important, these initiatives are an essential part of current and future systems biology.

Results

A mass spectral library consisting of experimentally derived tryptic peptide product ion spectra was generated based on liquid chromatography coupled to ion trap mass spectrometry (LC-IT-MS). Protein samples derived from Arabidopsis thaliana, Chlamydomonas reinhardii, Medicago truncatula, and Sinorhizobium meliloti were analysed. With currently 4,557 manually validated spectra associated with 4,226 unique peptides from 1,367 proteins, the database serves as a continuously growing reference data set and can be used for protein identification and quantification in uncharacterized biological samples. For peptide identification, several algorithms were implemented based on a recently published study for peptide mass fingerprinting [2] and tested for false positive and negative rates. An algorithm which considers intensity distribution for match correlation scores was found to yield best results. For proof of concept, an LC-IT-MS analysis of a tryptic leaf protein digest was converted to mzData format and searched against the mass spectral library. The utility of the mass spectral library was also tested for the identification of phosphorylated tryptic peptides. We included in vivo phosphorylation sites of Arabidopsis thaliana proteins and the identification performance was found to be improved compared to genome-based search algorithms. Protein identification by ProMEX is linked to other levels of biological organization such as metabolite, pathway, and transcript data. The database is further connected to annotation and classification services via BioMoby.

Conclusion

The ProMEX protein/peptide database represents a mass spectral reference library with the capability of matching unknown samples for protein identification. The database allows text searches based on metadata such as experimental information of the samples, mass spectrometric instrument parameters or unique protein identifier like AGI codes. ProMEX integrates proteomics data with other levels of molecular organization including metabolite, pathway, and transcript information and may thus become a useful resource for plant systems biology studies. The ProMEX mass spectral library is available at http://promex.mpimp-golm.mpg.de/.
GenMAPP 2: new features and resources for pathway analysis
Authors: Salomonis Nathan , Hanspers Kristina , Zambon Alexander C , Vranizan Karen , Lawlor Steven C , Dahlquist Kam D , Doniger Scott W , Stuart Josh , Conklin Bruce R , Pico Alexander R
Published: June 2007

Background

Microarray technologies have evolved rapidly, enabling biologists to quantify genome-wide levels of gene expression, alternative splicing, and sequence variations for a variety of species. Analyzing and displaying these data present a significant challenge. Pathway-based approaches for analyzing microarray data have proven useful for presenting data and for generating testable hypotheses.

Results

To address the growing needs of the microarray community we have released version 2 of Gene Map Annotator and Pathway Profiler (GenMAPP), a new GenMAPP database schema, and integrated resources for pathway analysis. We have redesigned the GenMAPP database to support multiple gene annotations and species as well as custom species database creation for a potentially unlimited number of species. We have expanded our pathway resources by utilizing homology information to translate pathway content between species and extending existing pathways with data derived from conserved protein interactions and coexpression. We have implemented a new mode of data visualization to support analysis of complex data, including time-course, single nucleotide polymorphism (SNP), and splicing. GenMAPP version 2 also offers innovative ways to display and share data by incorporating HTML export of analyses for entire sets of pathways as organized web pages.

Conclusion

GenMAPP version 2 provides a means to rapidly interrogate complex experimental data for pathway-level changes in a diverse range of organisms.
Normalization and experimental design for ChIP-chip data
Authors: Peng Shouyong , Alekseyenko Artyom A , Larschan Erica , Kuroda Mitzi I , Park Peter J
Published: June 2007

Background

Chromatin immunoprecipitation on tiling arrays (ChIP-chip) has been widely used to investigate the DNA binding sites for a variety of proteins on a genome-wide scale. However, several issues in the processing and analysis of ChIP-chip data have not been resolved fully, including the effect of background (mock control) subtraction and normalization within and across arrays.

Results

The binding profiles of Drosophila male-specific lethal (MSL) complex on a tiling array provide a unique opportunity for investigating these topics, as it is known to bind on the X chromosome but not on the autosomes. These large bound and control regions on the same array allow clear evaluation of analytical methods.

We introduce a novel normalization scheme specifically designed for ChIP-chip data from dual-channel arrays and demonstrate that this step is critical for correcting systematic dye-bias that may exist in the data. Subtraction of the mock (non-specific antibody or no antibody) control data is generally needed to eliminate the bias, but appropriate normalization obviates the need for mock experiments and increases the correlation among replicates. The idea underlying the normalization can be used subsequently to estimate the background noise level in each array for normalization across arrays. We demonstrate the effectiveness of the methods with the MSL complex binding data and other publicly available data.

Conclusion

Proper normalization is essential for ChIP-chip experiments. The proposed normalization technique can correct systematic errors and compensate for the lack of mock control data, thus reducing the experimental cost and producing more accurate results.
Microarray for serotyping of Bartonella species
Authors: Bonhomme Cyrille J , Nappez Claude , Raoult Didier
Published: June 2007

Background

Bacteria of the genusBartonellaare responsible for a large variety of human and animal diseases. Serological typing ofBartonellais a method that can be used for differentiation and identification ofBartonellasubspecies.

Results

We have developed a novel multiple antigenic microarray to serotypeBartonellastrains and to select poly and monoclonal antibodies. It was validated using mouse polyclonal antibodies against 29Bartonellastrains. We then tested the microarray for serotyping ofBartonellastrains and defining the profile of monoclonal antibodies.

Bartonellastrains gave a strong positive signal and all were correctly identified. Screening of monoclonal antibodies towards the Gro EL protein ofB. clarridgeiaeidentified 3 groups of antibodies, which were observed with variable affinities againstBartonellastrains.

Conclusion

We demonstrated that microarray of spotted bacteria can be a practical tool for serotyping of unidentified strains or species (and also for affinity determination) by polyclonal and monoclonal antibodies. This could be used in research and for identification of bacterial strains.
Interaction of Salivary alpha-Amylase and Amylase-Binding-Protein A (AbpA) of Streptococcus gordonii with Glucosyltransferase of S. gordonii and Streptococcus mutans
Authors: Chaudhuri Biswendu , Rojek Jennifer , Vickerman M Margaret , Tanzer Jason M , Scannapieco Frank A
Published: June 2007

Background

Glucosyltransferases (Gtfs), enzymes that produce extracellular glucans from dietary sucrose, contribute to dental plaque formation by Streptococcus gordonii and Streptococcus mutans. The alpha-amylase-binding protein A (AbpA) of S. gordonii, an early colonizing bacterium in dental plaque, interacts with salivary amylase and may influence dental plaque formation by this organism. We examined the interaction of amylase and recombinant AbpA (rAbpA), together with Gtfs of S. gordonii and S. mutans.

Results

The addition of salivary alpha-amylase to culture supernatants of S. gordonii precipitated a protein complex containing amylase, AbpA, amylase-binding protein B (AbpB), and the glucosyltransferase produced by S. gordonii (Gtf-G). rAbpA was expressed from an inducible plasmid, purified from Escherichia coli and characterized. Purified rAbpA, along with purified amylase, interacted with and precipitated Gtfs from culture supernatants of both S. gordonii and S. mutans. The presence of amylase and/or rAbpA increased both the sucrase and transferase component activities of S. mutans Gtf-B. Enzyme-linked immunosorbent assay (ELISA) using anti-Gtf-B antibody verified the interaction of rAbpA and amylase with Gtf-B. A S. gordonii abp A-deficient mutant showed greater biofilm growth under static conditions than wild-type in the presence of sucrose. Interestingly, biofilm formation by every strain was inhibited in the presence of saliva.

Conclusion

The results suggest that an extracellular protein network of AbpA-amylase-Gtf may influence the ecology of oral biofilms, likely during initial phases of colonization.
Outcome measurement in clinical trials for ulcerative colitis: towards standardisation
Authors: Cooney Rachel M , Warren Bryan F , Altman Douglas G , Abreu Maria T , Travis Simon PL
Published: June 2007

Clinical trials on novel drug therapies require clear criteria for patient selection and agreed definitions of disease remission. This principle has been successfully applied in the field of rheumatology where agreed disease scoring systems have allowed multi-centre collaborations and facilitated audit across treatment centres. Unfortunately in ulcerative colitis this consensus is lacking. Thirteen scoring systems have been developed but none have been properly validated. Most trials choose different endpoints and activity indices, making comparison of results from different trials extremely difficult. International consensus on endoscopic, clinical and histological scoring systems is essential as these are the key components used to determine entry criteria and outcome measurements in clinical trials on ulcerative colitis. With multiple new therapies under development, there is a pressing need for consensus to be reached.
Changes in the incidence and outcome for early acute kidney injury in a cohort of Australian intensive care units
Authors: Bagshaw Sean M , George Carol , Bellomo Rinaldo ,   the ANZICS Database Management Committee
Published: June 2007

Introduction

There is limited information on whether the incidence of acute kidney injury (AKI) in critically ill patients has changed over time and there is controversy on whether its outcome has improved.

Methods

We interrogated the Australian New Zealand Intensive Care Society Adult Patient Database to obtain data on all adult admissions to 20 Australian intensive care units (ICUs) for ≥ 24 hours from 1 January 1996 to 31 December 2005. Trends in incidence and mortality for ICU admissions associated with early AKI were assessed.

Results

There were 91,254 patient admissions to the 20 study ICUs, with 4,754 cases of AKI, for an estimated crude cumulative incidence of 5.2% (95% confidence interval, 5.1 to 5.4). The incidence of AKI increased during the study period, with an estimated annual increment of 2.8% (95% confidence interval, 1.0 to 5.6, P = 0.04). The crude hospital mortality was significantly higher for patients with AKI than those without (42.7% versus 13.4%; odds ratio, 4.8; 95% confidence interval, 4.5 to 5.1; P < 0.0001). There was also a decrease in AKI crude mortality (annual percentage change, -3.4%; 95% confidence interval, -4.7 to -2.12; P < 0.001), however, which was not seen in patients without AKI. After covariate adjustment, AKI remained associated with a higher mortality (odds ratio, 1.23; 95% confidence interval, 1.14 to 1.32; P < 0.001) and there was a declining trend in the odds ratio for hospital mortality.

Conclusion

Over the past decade, in a large cohort of critically ill patients admitted to 20 Australian ICUs, there has been a significant rise in the incidence of early AKI while the mortality associated with AKI has declined.
Toxicogenomic analysis of Caenorhabditis elegans reveals novel genes and pathways involved in the resistance to cadmium toxicity
Authors: Cui Yuxia , McBride Sandra J , Boyd Windy A , Alper Scott , Freedman Jonathan H
Published: June 2007

Background

Exposure to cadmium is associated with a variety of human diseases. At low concentrations, cadmium activates the transcription of stress-responsive genes, which can prevent or repair the adverse effects caused by this metal.

Results

Using Caenorhabditis elegans, 290 genes were identified that are differentially expressed (>1.5-fold) following a 4 or 24 hour exposure to cadmium. Several of these genes are known to be involved in metal detoxification, including mtl-1, mtl-2, cdr-1 and ttm-1, confirming the efficacy of the study. The majority, however, were not previously associated with metal-responsiveness and are novel. Gene Ontology analysis mapped these genes to cellular/ion trafficking, metabolic enzymes and proteolysis categories. RNA interference-mediated inhibition of 50 cadmium-responsive genes resulted in an increased sensitivity to cadmium toxicity, demonstrating that these genes are involved in the resistance to cadmium toxicity. Several functional protein interacting networks were identified by interactome analysis. Within one network, the signaling protein KEL-8 was identified. Kel-8 protects C. elegans from cadmium toxicity in a mek-1 (MAPKK)-dependent manner.

Conclusion

Because many C. elegans genes and signal transduction pathways are evolutionarily conserved, these results may contribute to the understanding of the functional roles of various genes in cadmium toxicity in higher organisms.
Measuring the accuracy of genome-size multiple alignments
Authors: Prakash Amol , Tompa Martin
Published: June 2007

Whole-genome alignments are invaluable for comparative genomics. Before doing any comparative analysis on a region of interest, one must have confidence in that region's alignment. We provide a methodology to measure the accuracy of arbitrary regions of these alignments, and apply it to the UCSC Genome Browser's 17-vertebrate alignment. We identify 9.7% (21 Mbp) of the human chromosome 1 alignment as suspiciously aligned. We present independent evidence that many of these suspicious regions represent misalignments.
Should I Stay or Should I Go?
Authors: ROESCH MATTHEW R. , CALU DONNA J. , BURKE KATHRYN A. , SCHOENBAUM GEOFFREY
Published: June 2007

Abstract:  Animals prefer a small, immediate reward over a larger delayed reward (time discounting). Lesions of the orbitofrontal cortex (OFC) can either increase or decrease the breakpoint at which animals abandon the large delayed reward for the more immediate reward as the delay becomes longer. Here we argue that the varied effects of OFC lesions on delayed discounting reflect two different patterns of activity in OFC; one that bridges the gap between a response and an outcome and another that discounts delayed reward. These signals appear to reflect the spatial location of the reward and/or the action taken to obtain it, and are encoded independently from representations of absolute value. We suggest a dual role for output from OFC in both discounting delayed reward, while at the same time supporting new learning for them.
Reward‐Related Responses in the Human Striatum
Authors: DELGADO MAURICIO R.
Published: June 2007

Abstract:  Much of our knowledge of how reward information is processed in the brain comes from a rich animal literature. Recently, the advancement of neuroimaging techniques has allowed researchers to extend such investigations to the human brain. A common finding across species and methodologies is the involvement of the striatum, the input structure of the basal ganglia, in a circuit responsible for mediating goal‐directed behavior. Central to this idea is the role of the striatum in the processing of affective stimuli, such as rewards and punishments. The goal of this article is to probe the human reward circuit, specifically the striatum and its subdivisions, with an emphasis on how the affective properties of outcomes or feedback influence the underlying neural activity and subsequent decision making. Discussion will first focus on anatomical and functional considerations regarding the striatum that have emerged from animal models. The rest of the article will center on how human neuroimaging studies map to findings from the animal literature, and how more recently, this research can be extended into the social and economic domains.
Reward Prediction Error Computation in the Pedunculopontine Tegmental Nucleus Neurons
Authors: KOBAYASHI YASUSHI , OKADA KEN‐ICHI
Published: June 2007

Abstract:  In this article, we address the role of neuronal activity in the pathways of the brainstem–midbrain circuit in reward and the basis for believing that this circuit provides advantages over previous reinforcement learning theory. Several lines of evidence support the reward‐based learning theory proposing that midbrain dopamine (DA) neurons send a teaching signal (the reward prediction error signal) to control synaptic plasticity of the projection area. However, the underlying mechanism of where and how the reward prediction error signal is computed still remains unclear. Since the pedunculopontine tegmental nucleus (PPTN) in the brainstem is one of the strongest excitatory input sources to DA neurons, we hypothesized that the PPTN may play an important role in activating DA neurons and reinforcement learning by relaying necessary signals for reward prediction error computation to DA neurons. To investigate the involvement of the PPTN neurons in computation of reward prediction error, we used a visually guided saccade task (VGST) during recording of neuronal activity in monkeys. Here, we predict that PPTN neurons may relay the excitatory component of tonic reward prediction and phasic primary reward signals, and derive a new computational theory of the reward prediction error in DA neurons.
Still at the Choice‐Point
Authors: BALLEINE BERNARD W. , OSTLUND SEAN B.
Published: June 2007

Abstract:  Contrary to classic stimulus–response (S‐R) theory, recent evidence suggests that, in instrumental conditioning, rats encode the relationship between their actions and the specific consequences that these actions produce. It has remained unclear, however, how encoding this relationship acts to control instrumental performance. Although S‐R theories were able to give a clear account of how learning translates into performance, the argument that instrumental learning constitutes the acquisition of information of the form “response R leads to outcome O” does not directly imply a particular performance rule or policy; this information can be used both to perform R and to avoid performing R. Recognition of this problem has forced the development of accounts that allow the O and stimuli that predict the O (i.e., S‐O) to play a role in the initiation of specific Rs. In recent experiments, we have used a variety of behavioral procedures in an attempt to isolate the processes that contribute to instrumental performance, including outcome devaluation, reinstatement, and Pavlovian–instrumental transfer. Our results, particularly from experiments assessing outcome–selective reinstatement, suggest that both “feed‐forward” (O‐R) and “feed‐back” (R‐O) associations are critical and that although the former appear to be important to response selection, the latter—together with processes that determine outcome value—mediate response initiation. We discuss a conceptual model that integrates these processes and its neural implementation.
Serotonin and the Evaluation of Future Rewards
Authors: SCHWEIGHOFER NICOLAS , TANAKA SAORI C. , DOYA KENJI
Published: June 2007

Abstract:  The ability to select an action by considering both delays and amount of reward outcome is critical for survival and well‐being of animals and humans. Previous animal experiments suggest a role of serotonin in action choice by modulating the evaluation of delayed rewards. It remains unclear, however, through which neural circuits, and through what receptors and intracellular mechanisms, serotonin affects the evaluation of delayed rewards. Here, we review experimental studies and computational theory of decisions under delayed rewards, and propose that serotonin controls the timescale of reward prediction by regulating neural activity in the basal ganglia.
Receptor Theory and Biological Constraints on Value
Authors: BERNS GREGORY S. , CAPRA C. MONICA , NOUSSAIR CHARLES
Published: June 2007

Abstract:  Modern economic theories of value derive from expected utility theory. Behavioral evidence points strongly toward departures from linear value weighting, which has given rise to alternative formulations that include prospect theory and rank‐dependent utility theory. Many of the nonlinear forms for value assumed by these theories can be derived from the assumption that value is signaled by neurotransmitters in the brain, which obey simple laws of molecular movement. From the laws of mass action and receptor occupancy, we show how behaviorally observed forms of nonlinear value functions can arise.
A “Good Parent” Function of Dopamine
Authors: HORVITZ JON C. , CHOI WON YUNG , MORVAN CECILE , EYNY YANIV , BALSAM PETER D.
Published: June 2007

Abstract:  While extracellular dopamine (DA) concentrations are increased by a wide category of salient stimuli, there is evidence to suggest that DA responses to primary and conditioned rewards may be distinct from those elicited by other types of salient events. A reward‐specific mode of neuronal responding would be necessary if DA acts to strengthen behavioral response tendencies under particular environmental conditions or to set current environmental inputs as goals that direct approach responses. As described in this review, DA critically mediates both the acquisition and expression of learned behaviors during early stages of training, however, during later stages, at least some forms of learned behavior become independent of (or less dependent upon) DA transmission for their expression.
Cost, Benefit, Tonic, Phasic
Authors: NIV YAEL
Published: June 2007

Abstract:  The role of dopamine in decision making has received much attention from both the experimental and computational communities. However, because reinforcement learning models concentrate on discrete action selection and on phasic dopamine signals, they are silent as to how animals decide upon the rate of their actions, and they fail to account for the prominent effects of dopamine on response rates. We suggest an extension to reinforcement learning models in which response rates are optimally determined by balancing the tradeoff between the cost of fast responding and the benefit of rapid reward acquisition. The resulting behavior conforms well with numerous characteristics of free‐operant responding. More importantly, this framework highlights a role for a tonic signal corresponding to the net rate of rewards, in determining the optimal rate of responding. We hypothesize that this critical quantity is conveyed by tonic levels of dopamine, explaining why dopaminergic manipulations exert a global affect on response rates. We further suggest that the effects of motivation on instrumental rates of responding are mediated through its influence on the net reward rate, implying a tight coupling between motivational states and tonic dopamine. The relationships between phasic and tonic dopamine signaling, and between directing and energizing effects of motivation, as well as the implications for motivational control of habitual and goal‐directed instrumental action selection, are discussed.
Splitting the Difference
Authors: KNUTSON BRIAN , WIMMER G. ELLIOTT
Published: June 2007

So, nat'ralists observe, a flea Hath smaller fleas that on him prey; And these have smaller still to bite 'em; And so proceedad infinitum. —Jonathan Swift,On Poetry: A Rhapsody, 1733

Abstract: Animal research and human brain imaging findings suggest that reward processing involves distinct anticipation and outcome phases. Error terms in popular models of reward learning (such as the temporal difference [TD] model) do not distinguish between the updating of expectations in response to reward cues and outcomes. Thus, correlating a single error term with neural activation assumes recruitment of similar neural substrates at each update. Here, we split the error term to separately model reward prediction and prediction errors, and compare the fit of single versus split error terms to functional magnetic resonance imaging (FMRI) data acquired during a monetary incentive delay task. We speculate and find that while the nucleus accumbens computes gain prediction in response to cues, the mesial prefrontal cortex (MPFC) computes gain prediction errors in response to outcomes. In addition to offering a more comprehensive and anatomically situated view of reward processing, split error terms generate novel predictions about psychiatric symptoms and lesion‐induced deficits.
Model‐Based fMRI and Its Application to Reward Learning and Decision Making
Authors: O'DOHERTY JOHN P. , HAMPTON ALAN , KIM HACKJIN
Published: June 2007

Abstract:  In model‐based functional magnetic resonance imaging (fMRI), signals derived from a computational model for a specific cognitive process are correlated against fMRI data from subjects performing a relevant task to determine brain regions showing a response profile consistent with that model. A key advantage of this technique over more conventional neuroimaging approaches is that model‐based fMRI can provide insights into how a particular cognitive process is implemented in a specific brain area as opposed to merely identifying where a particular process is located. This review will briefly summarize the approach of model‐based fMRI, with reference to the field of reward learning and decision making, where computational models have been used to probe the neural mechanisms underlying learning of reward associations, modifying action choice to obtain reward, as well as in encoding expected value signals that reflect the abstract structure of a decision problem. Finally, some of the limitations of this approach will be discussed.
Fusion of Metabolic Function and Morphology: Sequential [18F]Fluorodeoxyglucose Positron-Emission Tomography/Computed Tomography Studies Yield New Insights Into the Natural History of Bone Metastases in Breast Cancer
Authors: Du Yong , Cullum Ian , Illidge Tim M. , Ell Peter J.
Published: June 2007

Purpose

By monitoring bone metastases with sequential [18F]fluorodeoxyglucose positron-emission tomography/computed tomography ([18F]FDG-PET/CT) imaging, this study investigates the clinical relevance of [18F]FDG uptake features of bone metastases with various radiographic appearances.

Patients and Methods

Bone metastases were found in 67 of 408 consecutive patients with known/suspected recurrent breast cancer on [18F]FDG-PET/CT, characterized by CT morphology changes and/or bony [18F]FDG uptake. Twenty-five of the patients had sequential [18F]FDG-PET/CT examinations (86 studies) over an average follow-up period of 23 months. The temporal changes in [18F]FDG uptake and corresponding CT morphology features of 146 bone lesions identified in these 25 patients were followed up and correlated with therapeutic outcome retrospectively.

Results

The 146 lesions were classified as osteolytic (77), osteoblastic (41), mixed-pattern (11), or no change/negative (17) on CT. The majority of the osteolytic (72; 93.5%) and mixed-pattern lesions (nine; 81.8%), but fewer of the osteoblastic lesions (25; 61%), showed increased [18F]FDG uptake. After treatment, 58 osteolytic lesions (80.5%) became [18F]FDG negative and osteoblastic on CT and only 14 relatively large lesions (19.5%) remained [18F]FDG avid. Of the 25 [18F]FDG-avid osteoblastic lesions, 13 (52%) became [18F]FDG negative, but 12 (48%) remained [18F]FDG avid and increased in size on CT. Five of the mixed-pattern lesions remained [18F]FDG avid after treatment. All 17 CT-negative lesions became [18F]FDG negative; however, nine of them became osteoblastic. None of the initially [18F]FDG-negative lesions showed [18F]FDG avidity during follow-up.

Conclusion

[18F]FDG uptake reflects the immediate tumor activity of bone metastases, whereas the radiographic morphology changes vary greatly with time among patients.
Fringe multiplication in three-dimensional photoelasticity
Authors: Post D
Published: June 2007

Isochromatic fringe multiplication by a factor of up to 17 is demonstrated for slices from three-dimensional frozen-stress models. With this method, sensitivity is increased by an order of magnitude, the taking of data is quick and easy and the interpretation of data is less subject to errors than compensation techniques.
The effect of strain rate on the plastic flow characteristics of steel and aluminium sheet
Authors: Bramley A N , Mellor P B
Published: June 2007

Work-hardening characteristics for sheet steel and aluminium have been obtained experimentally over a range of strain rates from 10−4 to 102/s. Use of the diaphragm test enables work-hardening characteristics to be obtained to much higher plastic strains than is possible in uniaxial tension.

Results for killed steel show that the slope of the work-hardening characteristics decreases with increase in strain rate. Tentative extrapolation of the results suggests that if similar tests could be carried out at a strain rate of 104 then the work hardening characteristic would be that of an ideally plastic solid. In the case of aluminium the above phenomenon is not so marked and it is not possible to make even a tentative extrapolation to higher strain rates.
Job Displacement Risk and the Cost of Business Cycles
Authors: Krebs Tom
Published: June 2007

This paper analyzes the welfare costs of business cycles when workers face uninsurable job displacement risk. The paper uses a simple macroeconomic model with incomplete markets to show that cyclical variations in the long-term earnings losses of displaced workers can generate arbitrarily large cost of business cycles even if the variance of individual income changes is constant over the cycle. In addition to the theoretical analysis, this paper conducts a quantitative study of the cost of business cycles using empirical evidence on the long-term earnings losses of US workers. The quantitative analysis shows that realistic variations in job displacement risk generate sizable costs of business cycles, even though a second-moment analysis would suggest negligible costs. (JEL E21, E24, E32, J63)
Efficient Kidney Exchange: Coincidence of Wants in Markets with Compatibility-Based Preferences
Authors: Roth Alvin E , Sönmez Tayfun , Ünver M. Utku
Published: June 2007

Patients needing kidney transplants may have donors who cannot donate to them because of blood or tissue incompatibility. Incompatible patient-donor pairs can exchange donor kidneys with other pairs only when there is a “double coincidence of wants.” Developing infrastructure to perform three-way as well as two-way exchanges will have a substantial effect on the number of transplants that can be arranged. Larger than three-way exchanges have less impact on efficiency. In a general model of type-compatible exchanges, the size of the largest exchanges required to achieve efficiency equals the number of types. (JEL C78, I12)
Harmonization and Side Payments in Political Cooperation
Authors: Harstad Bård
Published: June 2007

For two districts or countries that try to internalize externalities, I analyze a bargaining game under private information. I derive conditions for when it is efficient with uniform policies across regions—with and without side payments—and when it is efficient to prohibit side payments in the negotiations. While policy differentiation and side payments allow the policy to better reflect local conditions, they create conflicts between the regions and, thus, delay. The results also describe when political centralization outperforms decentralized cooperation, and they provide a theoretical foundation for the controversial “uniformity assumption” traditionally used by the fiscal federalism literature. (JEL C78, D72, D82, H77)
Meeting Strangers and Friends of Friends: How Random Are Social Networks?
Authors: Jackson Matthew O , Rogers Brian W
Published: June 2007

We present a dynamic model of network formation where nodes find other nodes with whom to form links in two ways: some are found uniformly at random, while others are found by searching locally through the current structure of the network (e.g., meeting friends of friends). This combination of meeting processes results in a spectrum of features exhibited by large social networks, including the presence of more high- and low-degree nodes than when links are formed independently at random, having low distances between nodes in the network, and having high clustering of links on a local level. We fit the model to data from six networks and impute the relative ratio of random to network-based meetings in link formation, which turns out to vary dramatically across applications. We show that as the random/network-based meeting ratio varies, the resulting degree distributions can be ordered in the sense of stochastic dominance, which allows us to infer how the formation process affects average utility in the network. (JEL D85, Z13)