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PubMed2005

Using points at infinity for parameter decoupling in camera calibration.

The majority of camera calibration methods, including the Gold Standard algorithm, use point-based information and simultaneously estimate all calibration parameters. In contrast, we propose a novel calibration method that exploits line orientation information and decouples the problem into two simpler stages. We formulate the problem as minimization of the lateral displacement between single projected image lines and their vanishing points. Unlike previous vanishing point methods, parallel line pairs are not required. Additionally, the invariance properties of vanishing points mean that multiple images related by pure translation can be used to increase the calibration data set size without increasing the number of estimated parameters. We compare this method with vanishing point methods and the Gold Standard algorithm and demonstrate that it has comparable performance.

Algorithms↗

PubMed2006

Robust point matching for nonrigid shapes by preserving local neighborhood structures.

In previous work on point matching, a set of points is often treated as an instance of a joint distribution to exploit global relationships in the point set. For nonrigid shapes, however, the local relationship among neighboring points is stronger and more stable than the global one. In this paper, we introduce the lotion of a neighborhood structure for the general point matching problem. We formulate point matching as an optimization problem to preserve local neighborhood structures during matching. Our approach has a simple graph matching interpretation, where each point is a node in the graph, and two nodes are connected by an edge if they are neighbors. The optimal match between two graphs is the one that maximizes the number of matched edges. Existing techniques are leveraged to search for an optimal solution with the shape context distance used to initialize the graph matching, followed by relaxation labeling updates for refinement. Extensive experiments show the robustness of our approach under deformation, noise in point locations, outliers, occlusion, and rotation. It outperforms the shape context and TPS-RPM algorithms on most scenarios.

Algorithms↗

PubMed2005

Action research: the revision of services at one mental health rehabilitation unit in the north of England.

This paper reports the experiences of people in one mental health rehabilitation unit in the north of England, where conventional individualized approaches have repeatedly failed, leading to bed blocking and inertia. An action research approach has been used to identify the key problems concerned, construct appropriate goals and formulate problem-solving plans, leading to the development of an alternative therapeutic regime. The new facility is based on a society-centred, recovery approach which emphasizes the principles of community involvement, social responsibility and meaningful occupation of time. This approach may be of transferable interest to others in the field. The paper outlines the history of the unit, describes the action research process, and presents the philosophy of care, nursing model, admission criteria and main assessment tool now being used. It concludes with an open review of the research process, exploring both positive and negative aspects.

Adolescent↗

PubMed2006

Two mathematical programming models of cheese manufacture.

The standardization problem faced by cheese makers is formulated as a nonlinear programming problem using the assumptions of the Van Slyke cheese yield formula. The objective function of the model is to minimize the net cost of producing a given quantity of cheese subject to a set of production constraints. An approximation of the standardization problem formulated as a linear programming problem is also presented. Two different approaches to finding a solution are provided. The model is implemented in Microsoft Excel and solved with the standard add-in solver available in that program. An example is provided to contrast the difference between the nonlinear programming and its linear approximation, and a second example is used to illustrate the yield implications of ultrafiltered milk protein products in Cheddar cheese production. Additionally, a method for pricing inputs using the sensitivity analysis generated by the solver is demonstrated.

Caseins↗

PubMed2005

[Results of inpatient psychiatric and psychotherapeutic treatment of patients with schizophrenia, schizoaffective and other psychotic disorders].

OBJECTIVES: At the Tiefenbrunn hospital, patients suffering from severe psychiatric and psychosomatic disorders are treated. The treatment concept is psychodynamically oriented. Psychopharmacological treatments are included if necessary. This article reports the results of the treatment of a sample of patients with schizophrenic and other psychotic disorders (ICD-10: F20-F25). METHODS: An unselected sample of N = 33 patients was studied upon admission and before discharge with a set of routinely administered standardized instruments. RESULTS: According to the data, all of these patients were severely disturbed: Upon admission to the clinic, they showed high pathological values in the Beeintrachtigungs- Schwere-Score (degree of impairment score; Schepank 1995), the Symptom Checklist SCL-90-R (Franke 1995), the Inventory of Interpersonal Problems (Horowitz et al. 1994), as well as a high degree of comorbid disorders. A comparison of the data at admission and at discharge shows that these patients improved significantly and substantially concerning symptoms, interpersonal problems, contentedness with life and individually formulated target problems. DISCUSSION: The results of the present study are discussed with regard to both the treatment of psychotic patients and the results of other studies.

Adult↗

PubMedDate not supplied

Minimax optimization-based inverse treatment planning for interstitial thermal therapy.

The following work represents the development and evaluation of a minimax optimization-based inverse treatment planning approach for interstitial thermal therapy of cancer and benign disease. The goal is to determine a priori optimal applicator placements and power level settings to maintain the minimum tumour temperature, Tmin, and maximum normal tissue temperature, Tmax within a prescribed therapeutic temperature range. The temperature distribution is approximated by a finite element method (FEM) solution of a bioheat transfer equation on a nonuniform finite element mesh. Lower and upper therapeutic temperature thresholds are specified in the tumour and surrounding normal tissues. A constrained minimax optimization problem is formulated to determine optimal applicator positions and power level settings that minimize the maximum (rather than average) temperature errors in the target tumour region and surrounding normal tissues. The optimization problem is formulated for two general classes of interstitial heating applicators, those with and without a surface cooling mechanism. The viability and sensitivity of this approach is investigated in the two-dimensional setting for various tumour shapes and blood perfusion levels using surface-cooled and direct-coupled interstitial ultrasound applicator power deposition models. These preliminary results indicate the utility of this approach for meeting a prescribed Tmin/Tmax-based clinical objective criterion, and its potential for generating optimal treatment plans that can withstand variations or uncertainty in blood perfusion levels.

Energy Transfer↗

PubMed2006

Finding a solution to the problem of pain: conceptual formulation and the development of the Pain Solutions Questionnaire (PaSol).

We report the development of the Pain Solutions Questionnaire (PaSol), an instrument designed to measure assimilative (efforts at changing or solving pain) and accommodative (accepting that pain cannot be solved, and changing life goals) responses to the problems associated with pain. Data were collected from 476 adults suffering from chronic pain. Exploratory and confirmatory factor analyses resulted in a 14-item instrument with an adequate oblique 4-factor structure: (1) Solving Pain scale (4 items), (2) Meaningfulness of Life Despite Pain scale (5 items), (3) Acceptance of the Insolubility of Pain scale (3 items), and (4) Belief in a Solution scale (2 items). The validity of the PaSol was further tested by its value in explaining disability and affective distress after controlling for the effects of the demographic characteristics and pain severity. The Meaningfulness of Life Despite Pain scale was important in explaining disability and affective distress. The Solving Pain scale had a unique and independent contribution in explaining affective distress. Results are discussed in terms of how a persistence in assimilative coping, even though the pain problem is insoluble, may increase hypervigilance, catastrophizing, distress and disability.

Adaptation, Psychological↗

PubMed1997

Theory of Electrode Polarization in Dielectrophoresis and Electrorotation

Experimental observations, previously reported in the low frequency regime of the spectrum in dielectrophoresis and electrorotation of plant protoplasts, have revealed serious discrepancies between the predictions of the "Shelled Model" and measurements. Much work has also been carried out in the theoretical realm to reconcile these discrepancies by introducing such mechanisms as charge flow on the surface of the cell and micromotion, but in all this the effects of electrode polarization have been neglected. Part of the problem lies in the rather formidable nature of the analysis that must be carried out with nonuniform fields since the entire system of governing partial differential equations must be considered. In the case of uniform fields it is convenient to formulate the problem in the language of ordinary differential equations. This problem is further exacerbated by the lack of a well defined boundary condition at the outer limit of the double layer. We have used the method of Green's functions, since this allows the consideration of partial differential equations in a more natural way than the other methods, in order to formulate the problem. The lack of a well defined boundary condition at the outer surface is dealt with by taking an integral transform of the governing equations and thus recovering a relationship between the applied and the far fields. The results of our analysis show that the double layer relaxation, in the selected model, is a very simple single relaxation process and its effect is to diminish the discrepancies between theory and experiment. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗

PubMedDate not supplied

Medium term planning of biopharmaceutical manufacture using mathematical programming.

Regulatory pressures and capacity constraints are forcing the biopharmaceutical industry to consider employing multiproduct manufacturing facilities running on a campaign basis. The need for such flexible and cost-effective manufacture poses a significant challenge for planning and scheduling. This paper reviews the problem of planning and scheduling of biopharmaceutical manufacture and presents a methodology for the planning of multiproduct biopharmaceutical manufacturing facilities. The problem is formulated as a mixed integer linear program (MILP) to represent the relevant decisions required within the planning process and is tested on two typical biopharmaceutical industry planning problems. The proposed formulation is compared with an industrial rule based approach, which it outperforms in terms of profitability. The results indicate that the developed formulation offers an effective representation of the planning problem and would be a useful decision tool for manufacturers in the biopharmaceutical industry particularly at times of limited manufacturing capacity.

Algorithms↗

PubMed2004

An "optimal" k-needle placement strategy and its application to guiding transbronchial needle aspirations.

This article addresses the problem of finding an "optimal" strategy for placing k biopsy needles, given a large number of possible initial needle positions. We consider two variations of the problem: (1) Calculate the smallest set of needles necessary to guarantee a successful biopsy; and (2) Given a number k, calculate k needles such that the probability of a successful biopsy is maximized. Note that "needle" is used as shorthand for the parameter vector that specifies the needle placement. Both problems are formulated in terms of two general, NP-hard optimization problems. Our k-needle placement strategy can be considered as "optimal" in the sense that we are able to formulate it as a known NP-hard problem for which it is believed (NP not equal P conjecture) that no efficient algorithm exists that computes the optimal solution. In other words, our strategy is "optimal" with respect to the best approximative algorithm known for the respective NP-hard problem. For the second variation we have implemented an approximative algorithm that is guaranteed to be within a factor of approximately 0.63 of the exact solution. Given a number k, the algorithm calculates k sets of parameters, each set specifying the placement of a needle and the corresponding probability of success. The resulting probabilities show that our approach can provide valuable decision support for the physician in choosing how many needles to place and how to place them.A typical example of a biopsy where the initial needle position is known approximately is a transbronchial needle aspiration (TBNA). We demonstrate how our "optimal" needle placement strategy can be used to achieve sensor-less guidance of TBNA. The basic idea is to use a patient-specific model of the tracheobronchial tree (from CT/MR) and our model for flexible endoscopes to preoperatively estimate the unknown position of the bronchoscope. The result is a set of candidate shapes for the unknown shape of the bronchoscope before needle placement or, in other words, a (large) number of possible initial needle positions. By parameterizing the handling of the bronchoscope, including the insertion of the biopsy needle, we are able to apply our "optimal" strategy. The result is a TBNA protocol that, if executed during the procedure, prescribes how to handle the bronchoscope to maneuver the needle into the target. With the aforementioned endoscope model, we present a new way of modeling long, flexible instruments. The algorithm requires no initialization or preprocessing and calculates the workspace of an instrument based on its insertion depth and a set of internal and external constraints.

Algorithms↗

PubMed2000

A philosophical and critical analysis of the European convention of bioethics.

The Convention for the Protection of Human Rights and Dignity of the Human Being with Regard to the Application of Biology and Medicine is now one of the most important bioethics texts from the point of view of international policy and law. It is the result of five years of discussions and negotiations between the different instances of the Council of Europe. In this article I analyze several problems. First, there are problems of articulation between the Convention and the joint Explanatory Report. The oriented exegesis of the Explanatory Report raises suspicion about the Convention, which appears as a smooth facade for an instrument actually serving ideological positions many people do not share. Second, there are problems of formulation within the Convention. These are mainly problems with articles that state prohibitions without any distinction, relativization, contextualization or sense of evolution. Finally, there are problems of substance, leading to the conclusion that the Convention is not a good illustration of the human rights philosophical tradition in the name of which it has been proclaimed. This tradition is the one of Enlightenment. And when Kant summarizes the motto of Enlightenment, the injunction is "Sapere Aude!": "Dare to know!" It is difficult to hear such a message through the Convention, and the Explanatory Report includes too many passages and sentences that mean the opposite.

Bioethics↗

PubMed2006

Analysing grouping of nucleotides in DNA sequences using lumped processes constructed from Markov chains.

The most commonly used models for analysing local dependencies in DNA sequences are (high-order) Markov chains. Incorporating knowledge relative to the possible grouping of the nucleotides enables to define dedicated sub-classes of Markov chains. The problem of formulating lumpability hypotheses for a Markov chain is therefore addressed. In the classical approach to lumpability, this problem can be formulated as the determination of an appropriate state space (smaller than the original state space) such that the lumped chain defined on this state space retains the Markov property. We propose a different perspective on lumpability where the state space is fixed and the partitioning of this state space is represented by a one-to-many probabilistic function within a two-level stochastic process. Three nested classes of lumped processes can be defined in this way as sub-classes of first-order Markov chains. These lumped processes enable parsimonious reparameterizations of Markov chains that help to reveal relevant partitions of the state space. Characterizations of the lumped processes on the original transition probability matrix are derived. Different model selection methods relying either on hypothesis testing or on penalized log-likelihood criteria are presented as well as extensions to lumped processes constructed from high-order Markov chains. The relevance of the proposed approach to lumpability is illustrated by the analysis of DNA sequences. In particular, the use of lumped processes enables to highlight differences between intronic sequences and gene untranslated region sequences.

3' Untranslated Regions↗

PubMed2002

Bayesian A* tree search with expected O(N) node expansions: applications to road tracking.

Many perception, reasoning, and learning problems can be expressed as Bayesian inference. We point out that formulating a problem as Bayesian inference implies specifying a probability distribution on the ensemble of problem instances. This ensemble can be used for analyzing the expected complexity of algorithms and also the algorithm-independent limits of inference. We illustrate this problem by analyzing the complexity of tree search. In particular, we study the problem of road detection, as formulated by Geman and Jedynak (1996). We prove that the expected convergence is linear in the size of the road (the depth of the tree) even though the worst-case performance is exponential. We also put a bound on the constant of the convergence and place a bound on the error rates.

Algorithms↗

PubMed2004

Spatiotemporal motion boundary detection and motion boundary velocity estimation for tracking moving objects with a moving camera: a level sets PDEs approach with concurrent camera motion compensation.

The purpose of this study is to investigate a method of tracking moving objects with a moving camera. This method estimates simultaneously the motion induced by camera movement. The problem is formulated as a Bayesian motion-based partitioning problem in the spatiotemporal domain of the image quence. An energy functional is derived from the Bayesian formulation. The Euler-Lagrange descent equations determine imultaneously an estimate of the image motion field induced by camera motion and an estimate of the spatiotemporal motion undary surface. The Euler-Lagrange equation corresponding to the surface is expressed as a level-set partial differential equation for topology independence and numerically stable implementation. The method can be initialized simply and can track multiple objects with nonsimultaneous motions. Velocities on motion boundaries can be estimated from geometrical properties of the motion boundary. Several examples of experimental verification are given using synthetic and real-image sequences.

Algorithms↗

PubMed2005

Haplotype assembly from aligned weighted SNP fragments.

Given an assembled genome of a diploid organism the haplotype assembly problem can be formulated as retrieval of a pair of haplotypes from a set of aligned weighted SNP fragments. Known computational formulations (models) of this problem are minimum letter flips (MLF) and the weighted minimum letter flips (WMLF; Greenberg et al. (INFORMS J. Comput. 2004, 14, 211-213)). In this paper we show that the general WMLF model is NP-hard even for the gapless case. However the algorithmic solutions for selected variants of WMFL can exist and we propose a heuristic algorithm based on a dynamic clustering technique. We also introduce a new formulation of the haplotype assembly problem that we call COMPLETE WMLF (CWMLF). This model and algorithms for its implementation take into account a simultaneous presence of multiple kinds of data errors. Extensive computational experiments indicate that the algorithmic implementations of the CWMLF model achieve higher accuracy of haplotype reconstruction than the WMLF-based algorithms, which in turn appear to be more accurate than those based on MLF.

Algorithms↗

PubMed1996

[Nurses' representations of the managerial function, what professional commitment does this mean?].

THE SUBJECT OF THIS RESEARCH: "What idea nurses have about the managerial function; from a professional point of view what commitments does this function entail?" is connected with: The fact that at a legislative level there is no reglementation of the managerial function. From a legal point of view, the nature of the commitments in connection with this function is not accurate enough as there is no law explaining exactly what does the job of charge nurse consist in. Therefore, the opinions the whole medical profession have about the managerial function are various. On the other hand, taking into consideration what charge nurses think about their own function can help to explain the behaviour as, usually the ideas determine the practice (cf. ABRIC 1994). The methodology used was based on a scientific procedure and first of all I had to break with my prejudices and wrong opinions which only give you the illusion that you can understand the matters. Readings and exploratory talks helped me in that way and so I could formulate the problem. I worked within this theoretical context and I practically tested the facts by means of semi-directed interviews. The result of the analysis invalidated the hypothesis put forward at the beginning. As regards to the idea nurses have about the managerial function, the difference expressed is more regarding the connection between the nurses values and those ones of the charge nurses, rather than regarding the adequacy between the function and the place of the charge nurse. This is somewhere the notion of project according to ARDOI-NO (1984) in which it is necessary to define the aim of the project first and to establish the means used for the realization after. To formulate the problem only--in our research: the job description--is not enough. It must be developped. So, this procedure enable me, first, to consider the problems differently and to study complicated situations in which we can feel uncertain. The question is at the same time to anticipate and to accept to discover something different. Therefore, there is no model explaining how to understand the complexity of a problem. The charge nurse who is, on one hand, responsible of a conformity must accept to discover, on the other hand, something new: it is one of the paradox of this function.

Attitude of Health Personnel↗

PubMed1989

Psychodynamic formulation, consensual response method, and interpersonal problems.

We describe a new method for aggregating psychodynamic formulations of independent clinicians. 15 patients (10 female and 5 male, aged 23-41) were interviewed before they began brief dynamic psychotherapy. Different panels of 8 formulators (drawn from a pool of 72 psychodynamic clinicians with 10-38 years of clinical experience) observed each videotaped interview and wrote individual formulations. The text of each formulation was divided into thought-units, and thought-units that occurred 3 or more times were combined into a final consensual formulation. (One case was formulated twice to demonstrate the replicability of the method). Other clinical raters then read each consensual formulation and judged, for a list of interpersonal problems, whether each problem was apt to be distressing for that patient. The raters were very successful in predicting which problems were later discussed in treatment. Predictions were best for formulations with a high proportion of interpersonal content.

Adult↗

PubMedDate not supplied

Productivity improvement in xanthan gum fermentation using multiple substrate optimization.

A novel and more comprehensive formulation of the optimal control problem that reflects the operational requirements of a typical industrial fermentation has been proposed in this work. This formulation has been applied to a fed-batch bioreactor with three control variables, i.e., feed rates of carbon source, nitrogen source, and an oxygen source, to result in a 148.7% increase in product formation. Xanthan gum production using Xanthomonas campestris has been used as the model system for this optimization study, and the liquid-phase oxygen supply strategy has been used to supply oxygen to the fermentation. The formulated optimization problem has several constraints associated with it due to the nature of the system. A robust stochastic technique, differential evolution, has been used to solve this challenging optimization problem. The infinite dimensional optimization problem has been approximated to a finite dimensional one by control vector parametrization. The state constraints that are path constraints have been addressed by using penalty functions and by integrating them over the total duration to ensure a feasible solution. End point constraints on final working volume of the reactor and on the final residual concentrations of carbon and nitrogen sources have been included in the problem formulation. Further, the toxicity of the oxygen source, H(2)O(2), has been addressed by imposing a constraint on its maximum usable concentration. In addition, the initial volume of the bioreactor contents and feed concentrations have been handled as decision variables, which has enabled a well-grounded choice for their values from the optimization procedure; adhoc values are normally used in the industry. All results obtained by simulation have been validated experimentally with good agreements between experimental and simulated values.

Algorithms↗