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The revenue risk is of great importance to ensure the success of a real toll public–private partnership (PPP) transportation project. Past research has proposed a revenue guarantee put option as an alternative way to quantify and potentially manage this risk. A practical, or commercial, limitation of this type of option is its requirement for an upfront premium payment, and a concessionaire is likely to shy away from additional monetary requirements. A collar option, which is a combination of a put and call option, not only overcomes this barrier but it also provides other benefits. Modifications to the basic collar’s structure can redistribute downside losses and upside profits to fulfil stakeholders’ needs and thus improve the effectiveness of risk management. The terms, applicability and limitations of a collar option are discussed, and a numerical example is developed to illustrate how to determine the strike prices of a collar option.

Combinatorial interaction testing (CIT) is a cost-effective sampling technique for discovering interaction faults in highly-configurable systems. Constrained CIT extends the technique to situations where some features cannot coexist in a configuration, and is therefore more applicable to real-world software. Recent work on greedy algorithms to build CIT samples now efficiently supports these feature constraints. But when testing a single system configuration is expensive, greedy techniques perform worse than meta-heuristic algorithms, because greedy algorithms generally need larger samples to exercise the same set of interactions. On the other hand, current meta-heuristic algorithms have long run times when feature constraints are present. Neither class of algorithm is suitable when both constraints and the cost of testing configurations are important factors. Therefore, we reformulate one meta-heuristic search algorithm for constructing CIT samples, simulated annealing, to more efficiently incorporate constraints. We identify a set of algorithmic changes and experiment with our modifications on 35 realistic constrained problems and on a set of unconstrained problems from the literature to isolate the factors that improve performance. Our evaluation determines that the optimizations reduce run time by a factor of 90 and accomplish the same coverage objectives with even fewer system configurations. Furthermore, the new version compares favorably with greedy algorithms on real-world problems, and, though our modifications were aimed at constrained problems, it shows similar advantages when feature constraints are absent.

Public-private partnerships (PPP) for infrastructure development and management have received significant attention in academic, institutional, and political circles over roughly the last two decades. This attention was prompted, to a great extent, by early experiments with PPP-type arrangements in Australia, Canada, and the United States coupled with the United Kingdom's Private Finance Initiative policy—not to mention the experience of other parts of the world such as Asia, continental Europe, and South America. PPP policies and practices have evolved in other world regions, but the United States remains a relatively slow mover in this market. While varying explanations for this circumstance are plausible, the situation can play to America's advantage since the nation can capitalize upon the tested experience of its international counterparts. Drawing upon data and information collected from two principal sources: (1) case histories of PPP projects in North America to date and (2) a scanning tour of Australia, Portugal, Spain, and the United Kingdom in 2008, misconceptions regarding PPPs are clarified, contemporary international policies and practices are characterized, and recommendations for implementing PPPs for transportation infrastructure are made. The principal intent of this paper is to trigger a dialogue about PPPs and how they might improve America's infrastructure assets.

Recent advances in network theory hold promise for improving how infrastructure managers make decisions about their portfolio of assets. A framework that incorporates contemporary perspectives of networks is presented, which permits modeling the topology of an infrastructure network. The framework is capable of characterizing the components of the overall system and subnetworks and the direct and indirect interactions among these components. This framework is applied to a transportation system, which allows the authors to investigate the importance of the various components as elements of a complex network and use this data to support transportation asset management. The study shows that the links determine how the infrastructure network grows and that problems like congestion can be addressed by analyzing other factors related to topology, such as speed, unit size, and lane width. The proposed methodology appears promising as an asset management tool.

IRF1 is a transcription factor that regulates key processes in the immune system and in tumour suppression. To gain further insight into IRF1's role in these processes, we searched for new target genes by performing chromatin immunoprecipitation coupled to a CpG island microarray (ChIP-chip). Using this approach we identified 202 new IRF1-binding sites with high confidence. Functional categorization of the target genes revealed a surprising cadre of new roles that can be linked to IRF1. One of the major functional categories was the DNA damage response pathway. In order to further validate our findings, we show that IRF1 can regulate the mRNA expression of a number of the DNA damage response genes in our list. In particular, we demonstrate that the mRNA and protein levels of the DNA repair protein BRIP1 [Fanconi anemia gene J (FANC J)] are upregulated after IRF1 over-expression. We also demonstrate that knockdown of IRF1 by siRNA results in loss of BRIP1 expression, abrogation of BRIP1 foci after DNA interstrand crosslink (ICL) damage and hypersensitivity to the DNA crosslinking agent, melphalan; a characteristic phenotype of FANC J cells. Taken together, our data provides a more complete understanding of the regulatory networks controlled by IRF1 and reveals a novel role for IRF1 in regulating the ICL DNA damage response.

Public—private partnerships (P3) have emerged as a popular strategy for infrastructure development worldwide. Within the United States, the momentum for P3 arrangements is building as states put enabling legislation in place, public authorities search for expedient solutions for the infrastructure funding gap, and investor capital becomes increasingly attracted by the risk/return profile of infrastructure assets. Proponents of P3's tout advantages whereas detractors claim that the expected benefits rarely materialize, or they are obtained at too great an expense. Thus, the following question arises: Are P3's effective as infrastructure development strategies? A framework, which might serve to both structure and assess P3 programs and projects, is presented. The framework has evolved since its original introduction and is underpinned by the notion that P3 strategies must balance the interests of society, state, industry, and the market for ultimate success. A case study of its application is presented to illustrate its utilization and potential.

This paper describes bandwidth linearization techniques in phase-locked loop (PLL) design for common-clock serial link applications. Utilizing a continuously tunable single-input dual-path LC VCO and a constant-gain phase detector, a proposed architecture is well suited to implementing PLLs that must be compliant with standards that specify minimum and maximum allowable bandwidths such as PCI Express Gen2 or FB-DIMM applications. A prototype 4.75 to 6.1-㎓ PLL is implemented in 90-nm CMOS. Measurement results show that the PLL bandwidth and random jitter (RJ) variations are well regulated and that the use of a differentially controlled dualpath VCO is important for deterministic jitter (DJ) performance.

Assessment of BOT project financial risk is generally performed by combining Monte Carlo simulation with discounted cash flow analysis. The outcomes of this risk assessment depend, to a significant extent, upon the total project uncertainty, which aggregates aleatory and epistemic uncertainties of key risk variables. Unlike aleatory uncertainty, modelling epistemic uncertainty is a rather difficult endeavour. In fact, BOT epistemic uncertainty may vary according to the significant information disclosed during the concession period. Two properties generally characterize the stochastic behaviour of the uncertainty of BOT epistemic variables: (1) the learning property and (2) the increasing uncertainty property. A new family of Markovian processes, the Martingale variance model and the general variance model, are proposed as an alternative modelling tool for BOT risk variables. Unlike current stochastic models, the proposed models can be adapted to incorporate a risk analyst's view of properties (1) and (2)....

Service life is a critical, yet somewhat nebulous consideration in the management of infrastructure assets. Although often defined in terms of deterioration and time to physical failure, infrastructure service life is also defined by nonphysical factors such as increasing loads and alternate levels of evaluation. A new conceptual model is presented defining infrastructure service life as a function of physical and nonphysical factors. The model reflects, for example, the idea that an asset can be evaluated at different performance levels, with accompanying trade-offs in moving from a lower level to a higher one. In addition, the model recognizes that alternative performance evaluation techniques can influence a decision maker's perception of serviceability and remaining service life. Several applications illustrate how the model offers a fresh perspective on bridge service life, a key consideration given the trend toward ever-increasing truck loads. Results described have various implications for policy making and infrastructure asset management.

The revenue risk is considerable in infrastructure project financing arrangements such as build-operate-transfer BOT .A potential mitigation strategy for the revenue risk is a governmental revenue guarantee, where the government secures a minimum amount of revenue for a project. Such a guarantee is: 1 only redeemable at distinct points in time; and 2 more economical if the government limits the guarantee's availability to the early portions of a BOT's concession period. Hence, a guarantee characterized by this type of structure takes the form of either a Bermudan or a simple multiple-exercise real option, depending upon the number of exercise opportunities afforded. The multi-least-squares Monte Carlo technique is presented and illustrated as a promising approach to determine the fair value of this variety of real option. This method is far more flexible than prevailing approaches, so it represents an important step toward improving risk mitigation and facilitating contractual and financial negotiations in BOT projects.

For the majority of the last century, infrastructure development and management has focused primarily upon capital construction. In addition, a substantial amount of the financing for infrastructure, particularly within the US, has come from federal sources as evidenced by the Interstate Highway System Program and the EPA Construction Grants Program. The proclivity to focus upon the capital development cycle and the reliance upon federal funding have generally limited innovation in approaches to infrastructure development and minimized the importance of lifecycle management. However, new methods for both delivering and financing infrastructure have experienced a rebirth over roughly the last two decades. Integrated delivery strategies such as design-build-operate have increased the emphasis upon viewing constructed facilities as systems and have forced the recognition that sustaining these facilities requires more than just the initial capital investment. Unfortunately, new delivery and financing techniqu...

We report the case of a 63-year-old man who presented with severe acute renal failure requiring dialysis 17 years after a successful renal transplant of a kidney from his daughter. Transplant kidney biopsy revealed post-transplant lymphoproliferative disorder-large B-cell lymphoma. A PET scan revealed widespread disease, particularly involving the transplanted kidney. The patient responded rapidly to chemotherapy with VACOP-B and rituximab, with a complete resolution of renal failure and of the findings from the PET scan. The patient was in remission for 6 months, while on chemotherapy, before he was found to have recurrence of the disease in cervical lymph nodes and died 1 month later with normal kidney function.

Effective risk management is essential for success in transportation project financing arrangements such as build–operate–transfer (BOT). Both sponsors and lenders consider the revenue risk an extremely important factor when they assess a BOT project's feasibility. One potential strategy for mitigating the revenue risk is a revenue guarantee, in which a guarantor secures a minimum amount of revenue for a project; such guarantees take the form of a put option. However, the inclusion of such guarantees in BOT arrangements is hampered by the lack of methods to determine the value, or the fair price, of these types of options. Current valuation techniques lack the flexibility to structure the options in a manner that is affordable to the government and attractive to the private sector. This significant shortcoming opens a research opportunity to explore the development of methods for valuing more flexible and affordable guarantee structures. This paper presents two new valuation methods, the multi–least squares Monte Carlo method and the multi-exercise boundary method, which model the revenue guarantee as a multiple-exercise real option. The two valuation methods successfully combine Monte Carlo simulation and dynamic programming techniques to price multiple-exercise real options. A hypothetical case study illustrates the application and the potential of the two methods to serve as tools for risk mitigation in BOT projects.

• Background Increased anxiety correlates with increased complications after acute myocardial infarction. Anxiety levels and use of anxiolytic agents have not been compared between smokers and nonsmokers hospitalized because of acute myocardial infarction. • Objectives To compare anxiety level, sociodemographic factors, and clinical variables between smokers and nonsmokers hospitalized with acute myocardial infarction and to examine predictors of use of β-blockers and anxiolytic agents among smokers and nonsmokers. • Methods Secondary data analysis of a prospective multisite study on anxiety in 181 smokers and 351 nonsmokers with acute myocardial infarction. Anxiety was measured by using the State Trait Anxiety Inventory and the anxiety subscale of the Basic Symptom Inventory within 72 hours of admission. • Results Smokers reported higher anxiety levels than nonsmokers reported on both anxiety scales. Female smokers reported the highest anxiety and peak pain levels of all, yet women were the least likely to receive anxiolytic agents. Smoking status was not a predictor for anxiety level when sex, peak pain, use of β-blockers in the hospital, and age were controlled for. However, smokers were twice as likely as nonsmokers to receive an anxiolytic agent and 60% more likely to receive a β-blocker in the emergency department, and smokers were 80% more likely than nonsmokers to receive an anxiolytic agent during hospitalization when these variables were controlled. • Conclusions Older female smokers are at risk for complications because they are older than their male counterparts and less likely to receive β-blockers and antianxiety medications in the emergency department.

Background Perigraft seromas are rare complications of insertion of PTFE hemodialysis grafts. They are often difficult to treat and recurrence is common. This study evaluates the incidence, potential etiologic variables, and management strategies for seromas after prosthetic arteriovenous graft (AVG) placement. Study design A retrospective analysis of all patients undergoing AVG placement between August 2002 and December 2005 was performed to identify all patients diagnosed with seroma requiring surgical intervention. Multiple variables were analyzed to determine potential risk factors for seroma formation and outcomes of various forms of surgical management. Results In this interval, 535 AVG were inserted in 427 patients. Ten patients presented with a seroma and underwent surgical treatment. Overall incidence of seroma formation was 1.7%. There was no significant difference in seroma formation based on gender, age, diabetes, lower extremity versus upper extremity placement, or loop forearm versus straight forearm grafts. A statistically significant difference was found between upper arm (p = 0.007) and lower arm grafts (p = 0.04), with upper arm grafts more prone to seroma formation. Patients undergoing bypass of the seromatous segment of graft have not had a recurrence, compared with those who were simply evacuated and have had a mean patency of 402 days. Conclusions Seroma complications after AVG insertion are higher in patients with upper arm grafts. To minimize this complication, meticulous operative technique is required. If a seroma develops, the graft might still be salvageable with aggressive management, including bypass of the involved segment.

Purpose The purpose of this study was to examine the relationships of psychosocial variables (social support, self-efficacy, and outcome expectations) to diabetes self-care behaviors and glycemic control in Caucasian and African American adults with type 2 diabetes. Methods Study participants were scheduled for outpatient visits at 1 of 3 clinical sites in the southeastern United States. All 91 participants completed 4 self-report measures: Social Support Questionnaire (SSQ), Self-efficacy Questionnaire (SEQ), Outcome Expectancy Questionnaire (OEQ), and The Diabetes Activities Questionnaire (TDAQ) at the time of the clinic visit. Long-term glycemic control was assessed by glycosylated hemoglobin analyses at the time of the clinic visit. Pearson product-moment correlations were used to determine whether significant relationships existed between scores on the SSQ, SEQ, OEQ, and TDAQ and glycosylated hemoglobin values. Two-sample t tests were used to detect differences in scores on the self-report measures and glycosylated hemoglobin values between the 2 racial groups. Results In all participants, no significant relationships were found between (1) social support and self-care behaviors and (2) self-efficacy and self-care behaviors. Self-care behaviors were significantly, positively correlated with outcome expectancy scores for the total group and for African Americans. No significant relationships were found between (1) social support and glycemic control, (2) self-efficacy and glycemic control, and (3) outcome expectations and glycemic control. African Americans reported less social support satisfaction than Caucasians did. Conclusions Psychosocial variables investigated in this study were not related to health outcomes of type 2 diabetes. Caucasians and African Americans were similar in these variables. It is important to investigate the relationships between other variables (eg, age, duration of diabetes, education) and self-care behaviors and glycemic control. Although African Americans experience higher rates of diabetes-related complications than Caucasians do, this may possibly be due to other factors (eg, heredity, financial barriers, inadequate health care). Additional investigations to study the relationships of these variables to diabetes control are warranted.

Service life is an important yet somewhat nebulous consideration in the planning of suspension bridge rehabilitation projects. While it is often thought of in terms of time to physical failure of the asset, bridge service life is also defined by non-physical factors such as changing traffic loads and alternate levels of evaluation. This paper develops a conceptual model that defines service life as a function of physical and non-physical factors, thus offering a fresh perspective from which to base a more rational discussion on heavy trucks and their impact on bridge service life. An illustrative example demonstrates how this model may be applied in practice at the project level. Finally, federal truck weight reform is a pressing issue in the USA, and this paper concludes with a discussion on the implications this model has for network level studies concerning the impact of truck weight reform on bridge service life.

Photooxidized tryptophan (TRP) in tissue culture medium elicits a transient cytochrome P450 (CYP1) induction response in cultured cells. We show here that exposure of TRP to window sunlight (aTRP) greatly increased the potency, efficacy, and duration of CYP1A induction by TRP in primary chick embryo hepatocytes and in vivo. Aqueous TRP exposed to sunlight for 7 days exhibited a 100-fold or greater increase in potency over TRP in medium. The induction response was sustained for at least 48 h and was comparable in efficacy to 2,3,7,8-tetrachlorodibenzo-p-dioxin. In hepatocytes, increases in mRNAs for CYP1A4 and CYP1A5, chick orthologs of mammalian CYP1A1 and 1A2, preceded increases in CYP1A proteins and enzyme activities, 7-ethoxyresorufin deethylase (EROD) for CYP1A4 and arachidonic acid epoxygenation for CYP1A5, consistent with a transcriptional mechanism. Aryl hydrocarbon receptor (AhR) dependence was evidenced by aTRP induction of EROD in wild-type Hepa1c1c7 cells but not in AhR-defective (c35) mutants. Preparations of aTRP were stable for many months at 4 degrees C and were relatively resistant to metabolism by hepatocytes or liver microsomes. Fractionation of aTRP by HPLC analysis coupled with EROD assays showed that aTRP contained multiple photoproducts and CYP1A inducing components, which varied in sensitivity to metabolism by hepatocytes. The previously identified TRP photoproduct, 6-formylindolo[3,2-b]carbazole (FICZ), was one component, but FICZ was not required for CYP1A induction by the aTRP mixture. These findings identify the indoor environment, and window sunlight in particular, as a new source of CYP1A inducers. Further, the evidence that biologically active metabolites of an endogenous substrate, arachidonic acid, are formed by aTRP-induced CYP1A provides a pathway by which TRP photoproducts, like toxic xenobiotics, could have significant physiologic effects.

The software gap - the discrepancy between the need for new software and the aggregate capacity of the workforce to produce it - is a serious problem for scientific software. Although users appreciate the convenience (and, thus, improved productivity) of using relatively high-level scripting languages, the slow execution speeds of these languages remain a problem. Lower level languages, such as C and Fortran, provide better performance for production applications, but at the cost of tedious programming and optimization by experts. If applications written in scripting languages could be routinely compiled into highly optimized machine code, a huge productivity advantage would be possible. It is not enough, however, to simply develop excellent compiler technologies for scripting languages (as a number of projects have succeeded in doing for MATLAB). In practice, scientists typically extend these languages with their own domain-centric components, such as the MATLAB signal processing toolbox. Doing so effectively defines a new domain-specific language. If we are to address efficiency problems for such extended languages, we must develop a framework for automatically generating optimizing compilers for them. To accomplish this goal, we have been pursuing an innovative strategy that we call telescoping languages. Our approach calls for using a library-preprocessing phase to extensively analyze and optimize collections of libraries that define an extended language. Results of this analysis are collected into annotated libraries and used to generate a library-aware optimizer. The generated library-aware optimizer uses the knowledge gathered during preprocessing to carry out fast and effective optimization of high-level scripts. This enables script optimization to benefit from the intense analysis performed during preprocessing without repaying its price. Since library preprocessing is performed only at infrequent "language-generation" times, its cost is amortized over many

This paper presents an empirical study of factors contributing to the success and failure of 24 large international construction firms originating in the United States, Europe, and Japan. The study is conducted using fundamental analysis, a methodology that is commonly applied in economics and investment practices to study the prospects of a company. Based on publicly available data, both quantitative and qualitative measures are developed and assessed collectively to derive insightful knowledge about corporate strategy and firm outlook. Preliminary conclusions drawn from this study include: (1) A universal formula for success is elusive.critical success factors can be uniquely derived from different modes of operational, financial, technological, and human-related conditions and (2) causes of failure are diverse, thus construction firms must consistently check the downside risks of all measures. Thus, debates concerning the merits of common dichotomies such as diversification versus focused differentiation appear rather hollow. These aspects of strategy are far from fixed and should instead be treated as variables. The findings suggest that an open perspective of strategy is necessary in construction organizations and provide the foundation for the development of a new strategic model for the industry.

A new conceptual model for corporate strategy in the construction industry is presented that is derived from two principal inputs. First, the fundamental components of the model are based upon observations drawn from an empirical study of 24 international firms competing in global engineering and construction markets. Second, the accumulated intellect of different strategic theories developed over four decades of strategic management research helps to fortify the model with theoretical propositions and establish linkages among the model's basic components. The proposed model is comprised of seven strategic fields, two organizational mechanisms and a boundary notion that divides a firm's internal setting from its external environment. The model's development leads to two central propositions: strategic fields and organizational mechanisms should function as variables to react with external dynamics, and the interaction of these variables consequently promotes higher order differentiation factors that will enhance the strategic outlook of a firm.

Public infrastructure owners are increasingly soliciting BOT arrangements to deliver needed infrastructure facilities. Such arrangements potentially preserve a public owner's capital capacity for allocation to projects that cannot support themselves by essentially ‘pulling’ projects from the private sector. Before soliciting these arrangements, however, owners should independently evaluate a project's economic viability to fully appraise the issues and variables involved. Unfortunately, project analysts often apply evaluation methods without regard for their assumptions and limitations. A case study of a toll road project in the USA provides the basis for examining the assumptions behind both traditional and option valuation models. The case demonstrates the use of an option pricing model to augment traditional project evaluation by capturing strategic considerations, in this case the value of project deferment. The presentation illustrates that the selection of a valuation model depends critically upon t...

Anxiety is common in critically ill patients and can adversely affect recovery if not properly assessed and treated. The objectives of this study were to: (1) identify the clinical indicators that critical care nurses consider to be the defining attributes of anxiety in critically ill patients; and (2) delineate the interventions that critical care nurses use to alleviate anxiety in their patients. A total of 2500 nurses who worked in adult critical care areas were randomly selected from the membership of the American Association of Critical Care Nurses. Nurses selected were mailed a survey designed to determine what they considered to be the important attributes of anxiety in their patients and what interventions they commonly used to manage anxiety. The 593 nurses (31.6% response rate) who responded identified 70 individual anxiety indicators and 61 anxiety management strategies that were categorized into four and three major categories, respectively. The four major anxiety assessment categories were: (1) physical/physiological; (2) behavioral; (3) psychological/cognitive; and (4) social. The three major anxiety management strategies were: (1) care techniques; (2) improving knowledge and communication; and (3) support. Critical care nurses reported numerous and distinctive anxiety indicators and management strategies. Further research is needed to examine exactly how appropriate and effective these assessment indicators and management strategies are.

Anxiety is common after acute myocardial infarction (AMI) and may induce complications and poorer outcome because of activation of the sympathetic nervous system and the hypothalamic pituitary adrenal axis. Little is known about critical care nurses' management of anxiety in the initial days after AMI.The purpose of this study was to describe pharmacological and nonpharmacological anxiety management practices in a sample of patients with AMI and to determine the association between patient self-reported anxiety level, clinician anxiety assessment, and subsequent anxiety management by clinicians.In this descriptive, correlational investigation, subjects (n = 101) were requested to complete the Spielberger State Anxiety Inventory (SAI) within 48 hours of hospital admission for AMI. After hospital discharge, the investigators performed a thorough medical records review to evaluate the use of pharmacological and nonpharmacological anxiety management strategies for the period that encompassed 12 hours before and 12 hours after administration of the SAI.Subjects were primarily white (93%), married (72%) individuals with a hospital admission Killip classification of I (71%). Documentation of subjective anxiety assessment was found for only 45 subjects (44.6%). Subject rating of anxiety with SAI ranged from 20 (no anxiety) to 77 (extreme anxiety; mean, 37.2 +/- 12.4). Seventy-two subjects had documentation of anxiety management (pharmacological, 25.7%; nonpharmacological, 45.6%). No significant relationship was seen between the subject SAI score and the clinician assessment of anxiety (lambda = 0.03; P.05). Although documentation was seen that 72 subjects received anxiety management, no association was found between the clinician evaluation of anxiety and the use of anxiety management strategies (pharmacological: lambda = 0.11; P = .65; nonpharmacological: lambda = 0.07; P = .08). A small but significant relationship was found between the subject SAI score and the use of pharmacological anxiety management (lambda = 0.10; P = .03) but no association was found between SAI score and the use of nonpharmacological anxiety management (lambda = 0.6; P = .50). Evaluation of efficacy was not routinely documented (pharmacological, 58%; nonpharmacological, 2%). Only 2 subjects (2%) received consultation to social work for management of anxiety.Anxiety was not systematically and accurately assessed or logically managed in this sample of patients with AMI. Critical care clinicians need a comprehensive understanding about the importance of anxiety to patient outcome in addition to objective, reliable, and valid anxiety measures and a useful repertoire of evidence-based management strategies to effectively manage anxiety. Effective management of anxiety positively influences patient outcome and should be a goal for all critical care patients.

The emergence of alternative project delivery and finance methods in developing and sustaining infrastructure assets increases the significance of valuing such facilities. As private participants are introduced into the delivery of public facilities, the balance of possible future cash flows with initial capital inflows is an essential aspect of ensuring project viability. Traditional valuation techniques, which provide a tangible basis for the ultimate investment decision, often are employed in project financial analysis. The uncertainty of future cash flows, however, presents unique challenges for the use of these traditional methods. Moreover, the active management and planning of infrastructure projects creates flexibility that is largely ignored by traditional valuation methods. The Dulles Greenway, a recent private highway venture, provides a perspective to understand how “options” are used intuitively throughout a large-scale project and how the “option” to wait and resolve uncertainty can be valued with simple techniques that supplement traditional valuation methods. This article retrospectively analyzes project cash flows and the decision to invest in the Dulles Greenway.

• Background Anxiety activates the sympathetic nervous system and hypothalamic-pituitary-adrenal axis and may increase morbidity and mortality in vulnerable critical care patients. Despite the adverse effects of anxiety, little is known about critical care nurses’ practices for assessing anxiety.• Objective To determine the importance that critical care nurses place on evaluating anxiety and to describe clinical indicators used to assess anxiety.• Methods Twenty-five hundred members of the American Association of Critical-Care Nurses received the Critical Care Nurse Anxiety Identification and Management Survey and were asked to rate the importance of anxiety assessment, to rate the importance of 61 anxiety indicators, and to select and rank the 5 most important anxiety indicators.• Results Seven hundred eighty-three completed surveys (31.6%) were returned by female (92.0%), white (88.6%) staff nurses (74.2%) who practiced critical care nursing 32.5 hours (SD, 12.3 hours) weekly. Nearly three quarters (71.3%) of respondents thought that anxiety assessment is very important. Only 2 indicators, agitation and patients’ verbalization of anxiety, were rated as very important to anxiety assessment. Thirty-nine indicators rated as important primarily included measurable physiological changes and observable behaviors. The top 5 anxiety indicators were agitation, increased blood pressure, increased heart rate, patients’ verbalization of anxiety, and restlessness.• Conclusion Important indicators of anxiety included observable behaviors and measurable physiological changes. Reliance on these criteria may produce an inaccurate and incomplete anxiety evaluation in vulnerable patients and lead to poorer outcomes. A comprehensive, systematic anxiety assessment tool for valid and reproducible evaluation of patients’ anxiety is needed.

Self-adaptive software systems monitor their state and then adapt when certain conditions are met, guided by a global utility function. In prior work we developed algorithms and conducted a post-hoc analysis demonstrating the possibility of adapting to software failures by judiciously changing configurations. In this paper we present the REFRACT framework that realizes this idea in practice by building on the self-adaptive Rainbow architecture. REFRACT extends Rainbow with new components and algorithms targeting failure avoidance. We use REFRACT in a case study running four independently executing Firefox clients with 36 passing test cases and 7 seeded faults. The study show that workarounds for all but one of the seeded faults are found and the one that is not found never fails -- it is guarded from failing by a related workaround. Moreover, REFRACT finds workarounds for eight configuration-related unseeded failures from tests that were expected to pass (and did under the default configuration). Finally, the data show that when a failure and its workaround are found, configuration guards prevent the failure from appearing again. In a simulation lasting 24 hours we see over 150 guard activations and no failures with workarounds remaining beyond 16 hours.

This study investigates segmentation with a novel invariant compactness constraint. The proposed prior is a high-order fractional term, which is not directly amenable to powerful optimizers. We derive first-order Gateâux derivative approximations of our compactness term and adopt an iterative trust region paradigm by splitting our problem into constrained sub-problems, each solving the approximation globally via a Lagrangian formulation and a graph cut. We apply our algorithm to the challenging task of abdominal aorta segmentation in 3D MRI volumes, and report quantitative evaluations over 30 subjects, which demonstrate that the results correlate well with independent manual segmentations. We further show the use of our method in several other medical applications and demonstrate that, in comparison to a standard level-set optimization, our algorithm is one order of magnitude faster.

When the Federal Aviation Reauthorization Act of 1996 established the Federal Aviation Administration (FAA) Airport Privatization Pilot Program, it was the intent of Congress to explore new sources of capital and investment from the private sector and pass the benefits and improvements to the users. During the existence of the pilot program it received 10 applications; the first successful concession in 2000 of the Stewart International Airport in New York was ended prematurely in 2007. The second closing has come through the use of a public-private partnership (PPP) in Puerto Rico. This deal is very different to a privatization, because ownership of the asset remains in the public hands, and benefits to the users are linked to specific operating standards. Required improvement is to the asset inside the concession agreement. Puerto Rico's project involved the 40-year lease for the financing, operation, maintenance, and improvement of the Luis Munoz Marin (LMM) International Airport, a transaction worth $2.6 billion. A case study of the LMM airport concession is presented, and features of it are compared with two other transactions in the pilot program.

Centerline extraction and segmentation of the spinal cord--an intensity varying and elliptical curvilinear structure under strong neighboring disturbance are extremely challenging. This study proposes the gradient competition anisotropy technique to perform spinal cord centerline extraction and segmentation. The contribution of the proposed method is threefold--1) The gradient competition descriptor compares the image gradient obtained at different detection scales to suppress neighboring disturbance. It reliably recognizes the curvilinearity and orientations of elliptical curvilinear objects. 2) The orientation coherence anisotropy analyzes the detection responses offered by the gradient competition descriptor. It enforces structure orientation consistency to sustain strong disturbance introduced by high contrast neighboring objects to perform centerline extraction. 3) The intensity coherence segmentation quantifies the intensity difference between the centerline and the voxels in the vicinity of the centerline. It effectively removes the object intensity variation along the structure to accurately delineate the target structure. They constitute the gradient competition anisotropy method which can robustly and accurately detect the centerline and boundary of the spinal cord. It is validated and compared using 25 clinical datasets. It is demonstrated that the proposed method well suits the applications of spinal cord centerline extraction and segmentation.

This study investigates segmentation with a novel invariant compactness constraint. The proposed prior is a high-order fractional term, which is not directly amenable to powerful optimizers. We derive first-order Gateâux derivative approximations of our compactness term and adopt an iterative trust region paradigm by splitting our problem into constrained sub-problems, each solving the approximation globally via a Lagrangian formulation and a graph cut. We apply our algorithm to the challenging task of abdominal aorta segmentation in 3D MRI volumes, and report quantitative evaluations over 30 subjects, which demonstrate that the results correlate well with independent manual segmentations. We further show the use of our method in several other medical applications and demonstrate that, in comparison to a standard level-set optimization, our algorithm is one order of magnitude faster.

During the decline of public funding over the past three decades, infrastructure modernization has become increasingly dependent upon new strategies for managing the asset collection, and these strategies place a renewed emphasis upon condition assessment, alternative financing, and project delivery methods. Evaluation of these strategies and their impacts on public infrastructure operating and capital budgets presents a significant opportunity for engineers and planners seeking to optimize the capital allocation process. Accounting and budgeting data are the most tangible of decision factors considered by decision makers. As such, this data plays a critical role in how decision makers address the key components of the capital allocation process. These key components include condition assessment, planning, financing, and acquisition. Beginning with a review of accounting and budgeting definitions, this paper describes the role of financial information among these components. Case studies of infrastructure development and recent applications of a decision-support system that assists engineers and planners with the analysis and comparison of infrastructure production strategies provide the basis for characterizing the effects of accounting and budgeting on capital allocation. Findings at the local government level suggest that the common usage of cash-basis accounting and line-item budgeting and the lack of cost accounting do not adequately support decision makers in effectively executing the capital allocation process. However, recent changes in local government financial reporting standards and applications of activity-based costing methods seek to improve accounting and budgeting practices for public managers and outside interests involved in capital investment decisions.

BACKGROUND: Although anxiety is common after acute myocardial infarction and can adversely affect physical recovery, it is not part of the routine clinical assessment of patients with myocardial infarction. Furthermore, evidence suggests that patients and clinicians differ significantly in their assessments of patients' anxiety levels. OBJECTIVES: To determine the extent to which clinicians assess anxiety in patients with acute myocardial infarction and to compare patients' self-ratings with their clinicians' assessments. METHODS: In a prospective, descriptive study, 101 patients used the Spielberger State Anxiety Index to assess their anxiety during the first 48 hours after admission for acute myocardial infarction. Patients' scores were compared with nurses' and physicians' assessments of the patients' anxiety as reported in the medical record. RESULTS: Only 45 patients (45%) had anxiety assessments noted in the record. Of those 45, 26 patients (58%) were described simply as anxious without any further description of the level of anxiety. Eleven (24%) of those 45 patients had behaviors of anxiety recorded, again without any indication of the level of anxiety. No association between patients' self-assessments and their clinicians' assessments was apparent (lambda = .03; P > .05). CONCLUSIONS: Anxiety was not routinely assessed, despite nearly half the patients reporting moderate to extreme anxiety when asked. When clinicians assessed anxiety, their assessments did not match patients' self-ratings of anxiety. A simple, easy-to-use instrument for discriminating levels of anxiety is needed.

Public owners are challenged by limited and constrained capital sources for acquiring and sustaining infrastructure facilities. They also generally lack supporting automation tools and techniques for analyzing capital investment and project execution decisions, elucidating the impact of these decisions in a holistic manner, and leveraging alternative delivery methods and financing means for competitive advantage. An automated decision support system in development at Massachusetts Institute of Technology provides an integrated planning framework for public owners and engineers to confront these issues. The system, called CHOICES, models life cycle cash flows of capital projects using variable delivery methods and finance options and aggregates them with forecasted operating revenues and expenses at a portfolio level. This paper describes the application of CHOICES to a municipality in Massachusetts. Capital program scenarios were developed using pace of execution and alternate funding sources as primary considerations. Development and analyses of the scenarios suggest that the current municipal environment hinders local infrastructure management and procurement. This is a first-order problem; its solution is likely to outweigh the choice of project delivery for many municipal governments, and it forces municipalities to consider a wide array of alternatives for fulfilling local requirements.

Seeking information is a common coping strategy of patients facing a stressful event. Persons differ, however, in how much information they want to help them in their coping process. Research-based practice related to patients' preferences for information is hampered by the lack of reliable, valid, and clinically useful instruments to measure preference for information. Furthermore, it is imperative that researchers and clinicians understand preference for information in different cultures to reflect the diversity of the needs of patients in clinical practice. This study was designed to determine the reliability and validity of three measures of preference for information—the Miller Behavioral Style Scale (MBSS), the Krantz Health Opinion Survey-Information Subscale (KHOS-I), and the Preference for Information Scale—in 106 U.S. and Korean cardiac catheterization subjects. The MBSS and the KHOS-I were found to have fair-to-excellent reliability and fair-to-moderate convergent validity. The lack of a correlation of either of these two instruments with the Preference for Information Scale does not support convergent validity for that instrument. © 2000 John Wiley & Sons, Res Nurs Health 23:310–318, 2000.

Over the last decade, universities have increasingly begun to recognize their responsibility to address the issues and problems confronting society. Many universities are responding to this challenge by developing formal partnerships with communities. This article describes a specific partnership between Boston College and its local contiguous community. It outlines the development of the partnership from a simple school-university engagement between a school principal and a school of education faculty member to a complex set of relationships involving (a) multiple disciplines and professions; (b) a set of complicated projects; (c) multiple funders; (d) a large number of faculty, students, practitioners, and community members; (e) multiple institutions interacting at multiple levels; and (f) many kinds and levels of outcomes. The centrality of the processes of colearning and interprofessional collaboration is highlighted. The factors contributing to the success of the partnership, as well as the ongoing c...

BACKGROUND: Anxiety after acute myocardial infarction influences both short- and long-term recovery. Therefore, determining specific subgroups of patients who have relatively higher anxiety levels is important. Published findings about gender differences in anxiety after acute myocardial infarction are conflicting. OBJECTIVES: To determine whether gender differences in anxiety after acute myocardial infarction exist and whether any of the sociodemographic and clinical variables that often differ between men and women with acute myocardial infarction interact with gender to influence anxiety. METHODS: A total of 424 patients with confirmed acute myocardial infarction were enrolled in this multicenter prospective study. Patients' anxiety level was measured within 72 hours of their arrival at the hospital by using the State Anxiety Inventory and the Brief Symptom Inventory. RESULTS: Women had significantly higher anxiety than did men according to both the State Anxiety Inventory (42 +/- 12.9 vs 37.7 +/- 12.5; P = .001) and the Brief Symptom Inventory (0.83 +/- 0.97 vs 0.63 +/- 0.71; P = .02). Of the sociodemographic and clinical variables examined, only marital status and income significantly interacted with gender to influence anxiety. Married women had higher anxiety than did single and widowed women, and married men had lower anxiety than did single men. Women with lower income had higher anxiety than did women with higher income; income was not related to anxiety in men. CONCLUSION: Women report significantly greater anxiety early after acute myocardial infarction than men do. Women's greater anxiety may be partially explained by marital status and lower income at the time of the infarction.

Forty-two patients (29 newly diagnosed) with high grade gliomas (n = 37), medulloblastoma (n = 2) or non-biopsied tumors (n = 3) with supratentorial (n = 24), brain stem (n = 11), posterior fossa (n = 5) or spinal (n = 2) location were eligible for this study with adequate organ function and no bone marrow tumor infiltration. Median patient age was 12.2 years (range, 0.7-46.8). A total of 600 mg/m2 BCNU, 900 mg/m2 thiotepa and 1500 or 750 mg/m2 etoposide (VP-16) was administered followed by autologous bone marrow reinfusion (ABMR). Twenty-one newly diagnosed patients received local irradiation (RT) post ABMR. Nine early deaths were observed (21%), as well as one secondary graft failure. Half of the patients aged 18 years or older experienced toxic deaths, whereas only 15% of patients younger than 18 years experienced toxic death (P = 0.05). Of 25 evaluable newly diagnosed patients, 20% achieved complete remission (CR) and 4% partial remission (PR), while 28% remained in continuing complete remission (CCR) and 44% remained with stable disease prior to RT. Of eight evaluable patients with recurrent disease, one achieved CR and two PR, while one remained in CCR and four with stable disease for 1 to 110.2 months. Overall survival was 36%, 24% and 17% at 1, 2 and 3 years following ABMR, with three newly diagnosed patients and one patient treated for recurrent disease being alive, without disease progression 64.4, 67.0, 86.3 and 110.2 months after ABMR, respectively. The combination of high-dose BCNU/ thiotepa/VP-16 has substantial toxicity but definite activity for high risk CNS tumors. Similar protocols with lower toxicity merit further evaluation in both newly diagnosed and recurrent CNS tumors.

Since World War II, the American strategy for infrastructure procurement has evolved to rely primarily upon a single delivery method, design/bid/build. While this strategy was used to implement massive federal investment in highways, transit systems, and wastewater treatment, it has restricted state and local flexibility in aligning the procurement process to achieve best value for locally funded projects. The engineering, procurement, and construction community in the United States has now recognized the limitations of a procurement process designed to support a single delivery method. Change is coming, and the transition to a new process will challenge public owners in novel, but meaningful ways. This paper focuses upon shifting from the current paradigm toward a new model that supports simultaneous use of multiple project delivery methods. The discussion and frameworks provided are the result of a variety of research efforts by the Infrastructure Systems Development Research team at the Massachusetts Institute of Technology. Studies of the history of American infrastructure, analyses of case studies across the country, development of decision support models for capital programming, and real applications to municipal infrastructure planning provide the underpinnings for the results and conclusions presented.

In the United States, swine salmonellosis is most often attributed to infections by Salmonellaserovar choleraesuis. As a host-adapted pathogen rarely found in nonswine sources,S. choleraesuis is thoughtto be spread primarily via horizontal transmission, with carrier animals playing an important role. Little hasbeen reported regarding infection of neonatal piglets, particularly regarding their potential to become carriers.Evidence reported herein demonstrates that piglets experimentally infected by S. choleraesuis at 2 days of agewere capable of shedding the pathogen for up to 85 days postinfection, at which time the study was concluded.This study also presents findings supporting the use of GN-Hajna as a preenrichment medium for the isolationof S. choleraesuis.Salmonella choleraesuis infections account for more than90% of the US cases of swine salmonellosis. 12 Salmonellosiscaused by S. choleraesuis typically occurs as a postweaningsepticemia or enterocolitis and often occurs in operationsthat commingle pigs of different ages.

Spontaneous rupture of the liver has been described in association with many benign and malignant conditions. We report, to our knowledge, the first case of spontaneous rupture of the liver upon revascularization, requiring total hepatectomy and portocaval shunt, followed by successful retransplantation. Routine pathological examination of the explanted liver failed to reveal the etiology of the rupture. However, electron microscopy demonstrated abnormal collagen in the hepatic arterial wall compatible with a collagen disorder such as Ehlers-Danlos type IV disease. We conclude that the donor liver had a previously undiagnosed collagen disorder. Review of the literature does not preclude the use of livers from donors with a history of connective tissue disorders. Based on our experience one should exercise caution when using livers from such donors. With a history of connective tissue disorder in an immediate family member, further tests should be performed in the donor to rule out a subclinical connective tissue disorder. In addition, a review of all patients reported thus far to have undergone total hepatectomy and portocaval shunt, followed by liver transplantation as a two-stage procedure is presented.

BACKGROUND: Negative emotional reactions and difficulty in communicating are common in patients receiving mechanical ventilation and may adversely affect recovery from cardiac surgery. OBJECTIVE: To determine the effect of providing concrete objective information about emotional stress and difficulty in communicating related to mechanical ventilation to Korean cardiac surgery patients. METHODS: A quasi-experimental 2-group design was used. The 22 subjects in the control group received the usual information; the 21 in the experimental group received concrete objective information in addition to the usual information. State anxiety, negative affect, use of sedative and analgesic medications, and difficulty communicating were compared between the 2 groups after surgery. RESULTS: Patients who received concrete objective information experienced less anxiety and negative mood during mechanical ventilation, less difficulty in communicating, and a shorter intubation time than did patients in the control group. The 2 groups did not differ in the amount of sedative or analgesic medication used per hour during mechanical ventilation. CONCLUSIONS: Nursing interventions that include concrete objective information help cardiac patients cope with the stresses associated with surgery and mechanical ventilation.

Chronic pancreatitis is a disease of continuing inflammation that persists even after cessation of the initial etiologic agent. This condition can be clinically silent or associated with significant morbidity because of intractable pain, steatorrhea, loss of exocrine and endocrine function, and other complications. Chronic pancreatitis is primarily treated medically. Radiological, surgical, and endoscopic intervention is required for those patients with intractable pain and complications associated with the disease. Imaging (CT, sonography, endoscopic retrograde cholangiopancreatography, angiography) plays a significant role in diagnosis, in evaluating the anatomic and pathologic extent of disease and its complications, in excluding extrapancreatic causes of clinical manifestations, and in selecting among treatment alternatives.

The Wilms tumor suppressor WT1 encodes a zinc finger transcription factor that is expressed in glomerular podocytes during a narrow window in kidney development. By immunoprecipitation and protein microsequencing analysis, we have identified a major cellular protein associated with endogenous WT1 to be the inducible chaperone Hsp70. WT1 and Hsp70 are physically associated in embryonic rat kidney cells, in primary Wilms tumor specimens and in cultured cells with inducible expression of WT1. Colocalization of WT1 and Hsp70 is evident within podocytes of the developing kidney, and Hsp70 is recruited to the characteristic subnuclear clusters that contain WT1. The amino-terminal transactivation domain of WT1 is required for binding to Hsp70, and expression of that domain itself is sufficient to induce expression of Hsp70 through the heat shock element (HSE). Substitution of a heterologous Hsp70-binding domain derived from human DNAJ is sufficient to restore the functional properties of a WT1 protein with an amino-terminal deletion, an effect that is abrogated by a point mutation in DNAJ that reduces binding to Hsp70. These observations indicate that Hsp70 is an important cofactor for the function of WT1, and suggest a potential role for this chaperone during kidney differentiation.

This study was designed to investigate a possible mechanism of action by which octreotide acetate causes insulin suppression in the denervated pancreas. Canine tissue slices were placed in a pH-adjusted medium with varying concentrations of glucose and octreotide acetate: Experiment 1, 30 min in basal medium with 0.6 mg/ml glucose; Experiment 2, addition of 6.0 mg/ml glucose; Experiment 3, addition of 4 microg octreotide acetate/70 ml (comparable to 100 microg/25 kg body weight); Experiment 4, addition of 16 microg octreotide acetate/70 ml; Experiment 5, incubation with 6.0 mg glucose/ml and 4 microg octreotide acetate/70 ml; Experiment 6, incubation with 6.0 mg glucose/ml and 16 microg octreotide acetate/70 ml; Experiment 7, preincubation with 4 microg octreotide acetate/70 ml, then with 6.0 mg glucose/ml; and Experiment 8, preincubation with 16 microg octreotide acetate/70 ml, then with 6.0 mg glucose/ml. Medium levels of insulin, glucagon, and amylase were collected at intervals during the incubation periods. There was an appropriate increase in the rate of insulin release to glucose stimulation in the high-glucose (6.0 mg/ml) group. There was no significant inhibition of basal or glucose-stimulated insulin release with either simultaneous or pretreatment of the canine pancreatic tissue slices with either concentration of octreotide acetate. These studies support an indirect mechanism by which octreotide acetate exerts its inhibitory effect on endocrine and exocrine function in the canine pancreas transplant model.

Chempak (commercial physical properties database and properties estimation software) gives the thermodynamic and transport properties of pure compounds as functions of temperature and pressure for both liquid and vapor phases. Compound liquid properties are defined from the melting to the critical points. Vapor properties are defined from the melting point to 1300 K. The user may define up to 50 mixtures of compounds drawn from the database. In addition, the user may add up to 100 additional compounds defined by using the same techniques employed to construct the main database. Vapor properties are defined by the use of the Lee–Kesler and the Wu and Stiel equations of state. Vapor viscosity and thermal conductivity are defined using corresponding states methods. Liquid thermodynamic properties (except specific heat) are derived from the equation of state. All other liquid properties are defined by setting 11 data values from the melting to the critical point. The resulting property data arrays are interpolated against temperature.

The authors describe 2 patients who developed an iatrogenic arteriovenous fistula between a straight forearm polytetrafluoroethylene (PTFE) graft and an in situ cephalic vein after posterior puncture of the graft with a hemodialysis cannula. Diagnosis of this iatrogenic fistula was by careful inspection of the PTFE graft. The distal PTFE graft was functional, but the proximal graft was thrombosed at the ill-placed puncture site. Superficial veins on the anterior forearm exhibited a thrill and bruit. Treatment was simple ligation of the fistula and revascularization of the thrombosed segment of the PTFE graft. When the fistula occurred with a pseudoaneurysm, treatment was ligation of the fistula, exclusion of the pseudoaneurysm, and interposition graft to maintain vascular continuity. This complication of vascular access is not documented in the literature.

Free radical mediated lipid peroxidation (LPO) has been implicated in the pathogenesis of ischemic-reperfusion injury (IRI). To address the renoprotective effect(s) of LPO inhibition, the efficacy of the 21 aminosteroid U74389G was evaluated in three IRI models. In Model 1 51 unilateral nephrectomized rats that underwent 60 min of warm ischemia followed by a 72-hr reperfusion interval were treated with the test vehicle only, or 3, 6, or 12 mg/kg of U74389G intravenously, 5 min pre- or postischemia. In Model 2 Sprague-Dawley rats underwent sham operation (n=9), or 45 min of warm ischemia and 10 min of reperfusion with U74389G (6 mg/kg; n=10) or test vehicle only (n=10) administered intravenously over 10 min beginning 5 min prior to clamp release. After reperfusion, LPO was determined by assay of snap frozen tissue for thiobarbituric acid (TBA) concentrations (nmol/g tissue weight). In Model 3 domestic lean maid pigs (14-18 kg) underwent left nephrectomy with 30 min of warm ischemia, Collins C-4 flush, and 24 hr of cold storage preservation. Heterotopic autotransplantation and immediate contralateral nephrectomy was then performed in Group A-nonischemic controls (n=4), Group B-ischemic controls (n=5), and Group C-U74389G (6 mg/kg) administered preischemia and at autotransplantation (n=5). In Model 1 maximal renoprotection was demonstrated with the 6 mg/kg dose of U74389G administered after ischemia (ischemic control 72-hr serum creatinine (Cr) = 8.01+/-1.1 mg% vs. 3.32+/-0.96 mg%; ischemic control creatinine clearance = 0.069+/-0.03 ml/min vs. 0.206+/-0.04 ml/min; P

This paper addresses the trajectory planning problem for a task which requires positioning and orienting an object firmly grasped by two hands at a visually specified goal configuration in the horizontal plane. The motor task involves three degrees of freedom (two translational and one rotational), and the motions of the arms are constrained by the physical coupling through the held object. Experimentally measured trajectories of two arms in the coordinated positioning/orienting task are presented. The hypothesis that the rotational and translational components of motions are decoupled and independently planned is tested. Two explicit mathematical models to account for the kinematic features of the two-arm motions are formulated, and the predictions of the models are compared with the experimental data. Both models extend the minimum-jerk model to the two-arm coordinated motions case. The trajectories predicted by the models were found to be in qualitative agreement with the experimental data. However, neither model could account for the observed configuration dependence of the motions, nor for some of the properties of the measured velocity components of the motions. Our findings support the idea that the rotational and translational components of two-arm motions in the positioning/orienting task are independently planned in extra-personal space, and are further combined in a hierarchical fashion to produce the observed motions. The tested models may serve as a basis for further investigations of issues pertinent to the generation of two-arm trajectories.

The feature-interaction problem has been keeping researchers and practitioners in suspense for years. Although there has been substantial progress in developing approaches for modeling, detecting, managing, and resolving feature interactions, we lack sufficient knowledge on the kind of feature interactions that occur in real-world systems. In this position paper, we set out the goal to explore the nature of feature interactions systematically and comprehensively, classified in terms of order and visibility. Understanding this nature will have significant implications on research in this area, for example, on the efficiency of interaction-detection or performance-prediction techniques. A set of preliminary results as well as a discussion of possible experimental setups and corresponding challenges give us confidence that this endeavor is within reach but requires a collaborative effort of the community.