SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Natural and man-made emergencies are regular occurrences in the Greater Horn of Africa region. The underlying impoverishment of whole populations is increasing, making it more difficult to distinguish between humanitarian crises triggered by shocks and those resulting from chronic poverty. Shocks and hazards can no longer be seen as one-off events that trigger a one-time response. In countries that are both poor and exposed to frequent episodes of debilitating drought or chronic conflict, information needs tend to be different from the straightforward early warning/commodity accounting models of information systems that have proven reliable in past emergencies. This paper describes the interdependent components of a humanitarian information system appropriate for this kind of complex environment, noting the analytical links between the components and operational links to programme and policy. By examining a series of case studies from the Greater Horn region, the paper demonstrates that systems lacking one or more of these components will fail to provide adequate information--and thus incur humanitarian costs. While information always comes with a cost, the price of poor information--or none--is higher. And in situations of chronic vulnerability, in which development interventions are likely to be interspersed with both safety nets and emergency interventions on a recurrent basis, investment in improved information is a good investment from both a humanitarian and a financial viewpoint.
Explore the source record for details and available documents.
A conceptually new logic gate based on DNA has been devised. Methoxybenzodeazaadenine ((MD)A), an artificial nucleobase which we recently developed for efficient hole transport through DNA, formed stable base pairs with T and C. However, a reasonable hole-transport efficiency was observed in the reaction for the duplex containing an (MD)A/T base pair, whereas the hole transport was strongly suppressed in the reaction using a duplex where the base opposite (MD)A was replaced by C. The influence of complementary pyrimidines on the efficiency of hole transport through (MD)A was quite contrary to the selectivity observed for hole transport through G. The orthogonality of the modulation of these hole-transport properties by complementary pyrimidine bases is promising for the design of a new molecular logic gate. The logic gate system was executed by hole transport through short DNA duplexes, which consisted of the "logic gate strand", containing hole-transporting nucleobases, and the "input strand", containing pyrimidines which modulate the hole-transport efficiency of logic bases. A logic gate strand containing multiple (MD)A bases in series provided the basis for a sharp AND logic action. On the other hand, for OR logic and combinational logic, conversion of Boolean expressions to standard sum-of-product (SOP) expressions was indispensable. Three logic gate strands were designed for OR logic according to each product term in the standard SOP expression of OR logic. The hole-transport efficiency observed for the mixed sample of logic gate strands exhibited an OR logic behavior. This approach is generally applicable to the design of other complicated combinational logic circuits such as the full-adder.
Circuits and their involvement in complex dynamics are described in differential terms in Part I of this work. Here, we first explain why it may be appropriate to use a logical description, either by itself or in symbiosis with the differential description. The major problem of a logical description is to find an adequate way to involve time. The procedure we adopted differs radically from the classical one by its fully asynchronous character. In Sec. II we describe our "naive" logical approach, and use it to illustrate the major laws of circuitry (namely, the involvement of positive circuits in multistationarity and of negative circuits in periodicity) and in a biological example. Already in the naive description, the major steps of the logical description are to: (i) describe a model as a set of logical equations, (ii) derive the state table from the equations, (iii) derive the graph of the sequences of states from the state table, and (iv) determine which of the possible pathways will be actually followed in terms of time delays. In the following sections we consider multivalued variables where required, the introduction of logical parameters and of logical values ascribed to the thresholds, and the concept of characteristic state of a circuit. This generalized logical description provides an image whose qualitative fit with the differential description is quite remarkable. A major interest of the generalized logical description is that it implies a limited and often quite small number of possible combinations of values of the logical parameters. The space of the logical parameters is thus cut into a limited number of boxes, each of which is characterized by a defined qualitative behavior of the system. Our analysis tells which constraints on the logical parameters must be fulfilled in order for any circuit (or combination of circuits) to be functional. Functionality of a circuit will result in multistationarity (in the case of a positive circuit) or in a cycle (in the case of a negative circuit). The last sections deal with "more about time delays" and "reverse logic," an approach that aims to proceed rationally from facts to models. (c) 2001 American Institute of Physics.
The recent trend in the development of neurofuzzy systems has profoundly emphasized the importance of synergy between the fundamentals of fuzzy sets and neural networks. The resulting frameworks of the neurofuzzy systems took advantage of an array of learning mechanisms primarily originating within the theory of neurocomputing and the use of fuzzy models (predominantly rule-based systems) being well established in the realm of fuzzy sets. Ideally, one can anticipate that neurofuzzy systems should fully exploit the linkages between these two technologies while strongly preserving their evident identities (plasticity or learning abilities to be shared by the transparency and full interpretability of the resulting neurofuzzy constructs). Interestingly, this synergy still becomes a target yet to be satisfied. This study is an attempt to address the fundamental interpretability challenge of neurofuzzy systems. Our underlying conjecture is that the transparency of any neurofuzzy system links directly with the logic fabric of the system so the logic fundamentals of the underlying architecture become of primordial relevance. Having this in mind the development of neurofuzzy models hinges on a collection of logic driven processing units named here fuzzy (logic) neurons. These are conceptually simple logic-oriented elements that come with a well-defined semantics and plasticity. Owing to their diversity, such neurons form essential building blocks of the networks. The study revisits the existing categories of logic neurons, provides with their taxonomy, helps understand their functional features and sheds light on their behavior when being treated as computational components of any neurofuzzy architecture. The two main categories of aggregative and reference neurons are deeply rooted in the fundamental operations encountered in the technology of fuzzy sets (including logic operations, linguistic modifiers, and logic reference operations). The developed heterogeneous networks come with a well-defined semantics and high interpretability (which directly translates into the rule-based representation of the networks). As the network takes advantage of various logic neurons, this imposes an immediate requirement of structural optimization, which in this study is addressed by utilizing various mechanisms of genetic optimization (genetic algorithms). We discuss the development of the networks, elaborate on the interpretation aspects and include a number of illustrative numeric examples.
Deficits of logical reasoning have long been considered a hallmark of schizophrenia and delusional disorders. We provide a more precise characterization of "logic" and, by extension, of "deficits in logical reasoning." A model is offered to categorize different forms of logical deficits. This model acknowledges not only problems with making inferences, which is how logic deficits are usually conceived, but also problems in the acquisition and evaluation of premises (i.e., filtering of "input"). Early (1940-1969) and modern (1970-present) literature on logical reasoning and schizophrenia is evaluated within the context of the presented model. We argue that, despite a substantial history of interest in the topic, research to date has been inconclusive on the fundamental question of whether patients with delusional ideation show abnormalities in logical reasoning. This may be due to heterogeneous definitions of "logic," variability in the composition of patient samples, and floor effects among the healthy controls. In spite of these difficulties, the available evidence suggests that deficits in logical reasoning are more likely to occur due to faulty assessment of premises than to a defect in the structure of inferences. Such deficits seem to be provoked (in healthy individuals) or exacerbated (in patients with schizophrenia) by emotional content. The hypothesis is offered that delusional ideation is primarily affect-driven, and that a mechanism present in healthy individuals when they are emotionally challenged may be inappropriately activated in patients who are delusional.
A program logic model is used to make a program ready for an evaluation. It diagrammatically shows the relationships between the objectives of the program, program activities, indicators, and resources. This article describes an expanded logic model that has a greater focus on measurement of program performance. The expanded logic model specifies both outcome and process indicators, whereas other logic models only show service delivery indicators. Also, this article describes how the expanded logic model was used to develop a bicycle safety program. A workgroup established program boundaries and reviewed documents early in the process of developing the logic model. The workgroup developed the logic model which was subsequently reviewed by other stakeholders. The workgroup continually assessed the plausibility of the logic model. Challenges and advantages in using the logic model are discussed.
In medicine, the study of physiological and physiopathological problems is generally programmed by elaborating models which respond to the principals of formal logic. This gives the advantage of favouring the transformation of the formal model into a mathematical model of reference which responds to the principles of the set theories. All this is in the utopian wish to obtain as a result of each research, a net answer whether positive or negative, according to the Aristotelian principal of tertium non datur. Taking this into consideration, the A. briefly traces the principles of modal logic and, in particular, those of fuzzy logic, proposing that the latter substitute the actual definition of "logic with more truth values", with that perhaps more pertinent of "logic of conditioned possibilities". After a brief synthesis on the state of the art on the application of fuzzy logic, the A. reports an example of graphic expression of fuzzy logic by demonstrating how the basic glycemic data (expressed by the vectors magnitude) revealed in a sample of healthy individuals, constituted on the whole an unbroken continuous stream of set partials. The A. calls attention to fuzzy logic as a useful instrument to elaborate in a new way the analysis of scenario qualified to acquire the necessary information to single out the critical points which characterize the potential development of any biological phenomenon.
In empiricism, there are only two answers for a question: black or white. Yet, subjective meanings of human behaviours and responses toward health and illness cannot be simply explained with black and white. Gray zones are needed because they are characterized by complexity and require a contextual understanding. In this paper, we present and suggest fuzzy logic as an example of theoretical bases that help transcend the conflicts between objectivity and subjectivity, respect gray zones between black and white answers for questions, and provide a contextual understanding of complex nursing phenomenon. A historical review of fuzzy logic is followed by a definition of fuzzy logic. Then, fuzzy logic is discussed in terms of its compatibility with nursing epistemological views and philosophical thoughts. Fuzzy logic agrees with three categories of epistemological views of nursing, including correspondence, coherence and pragmatism. Fuzzy logic also agrees with four major philosophical thoughts in nursing, including postempiricism, pragmatism, feminism, and postmodernism. Based on the discussion, we propose that fuzzy logic be further explored, used and developed in research and practice in the nursing areas/situations/phenomena that are characterized by complexity, ambiguousness, and vagueness.
Some induction procedures result in trance logic as an essential feature of hypnosis. Trance logic is a voluntary state of acceptance of suggestions without the critical evaluation that would destroy the validity of the meaningfulness of the suggestion. Induction procedures in real and simulated conditions induce a conflict between two contradictory messages in experimental hypnosis. In military induction the conflict is much more subtle involving society's need for security and its need for ethics. Such conflicts are often construed by the subject as trance logic. Trance logic provides an opportunity for therapists using the phenomenology of "presence" to deal with the objectified concepts of "avoidance," "numbing" implicit in this kind of dysfunctional thinking in Posttraumatic Stress Disorder. An individual phenomenology of induction procedures and suggestions, which trigger trance logic, may lead to a resolution of logical fallacies and recurring painful memories. It invites a reconciliation of conflicting messages implicit in phobias and avoidance traumas. Such a phenomenological analysis of trance logic may well be a novel approach to restructure the meaning of trauma.
Integrated "ICT chromophore-receptor" systems show ion-induced shifts in their electronic absorption spectra. The wavelength of observation can be used to reversibly configure the system to any of the four logic operations permissible with a single input (YES, NOT, PASS 1, PASS 0), under conditions of ion input and transmittance output. We demonstrate these with dyes integrated into Tsien's calcium receptor, 1-2. Applying multiple ion inputs to 1-2 also allows us to perform two- or three-input OR or NOR operations. The weak fluorescence output of 1 also shows YES or NOT logic depending on how it is configured by excitation and emission wavelengths. Integrated "receptor(1)-ICT chromophore-receptor(2)" systems 3-5 selectively target two ions into the receptor terminals. The ion-induced transmittance output of 3-5 can also be configured via wavelength to illustrate several logic types including, most importantly, XOR. The opposite effects of the two ions on the energy of the chromophore excited state is responsible for this behaviour. INHIBIT and REVERSE IMPLICATION are two of the other logic types seen here. Integration of XOR logic with a preceding OR operation can be arranged by using three ion inputs. The fluorescence output of these systems can be configured via wavelength to display INHIBIT or NOR logic under two-input conditions. The superposition or multiplicity of logic gate configurations is an unusual consequence of the ability to simultaneously observe multiple wavelengths.
Intelligent systems require a systematic way to represent and handle temporal information containing uncertainty. In particular, a logical framework is needed that can represent uncertain temporal information and its relationships with logical formulae. Fuzzy linear temporal logic (FLTL), a generalization of propositional linear temporal logic (PLTL) with fuzzy temporal events and fuzzy temporal states defined on a linear time model, was previously proposed for this purpose. However, many systems are best represented by branching time models in which each state can have more than one possible future path. In this paper, fuzzy branching temporal logic (FBTL) is proposed to address this problem. FBTL adopts and generalizes concurrent tree logic (CTL*), which is a classical branching temporal logic. The temporal model of FBTL is capable of representing fuzzy temporal events and fuzzy temporal states, and the order relation among them is represented as a directed graph. The utility of FBTL is demonstrated using a fuzzy job shop scheduling problem as an example.
Using an automatic computerized perimeter developed by Heijl & Krakau (1975b) three different perimetric test logics, one simple (I) and two more complicated and time-consuming (II & III) were investigated in practical experiments on healthy normal test subjects and patients and in computer simulated tests. The patients either had a verified diagnosis of glaucoma or glaucoma was suspected. The best consistency in measured thresholds was obtained with test logic II, in which an averaging procedure is used. The variation of the results was larger in pathological than in normal visual fields. All test logics investigated readily detected the pathological field defects, but blind spots could easier pass unrecognized with the simplest logic than with the other two logics. The conclusion is drawn that a simple test logic can be used for perimetry in glaucoma suspects if no visual field defect has previously been documented. For the follow-up of pathological fields a fairly complicated test logic, e.g. using averaging, is preferable.
IMM/Def is a prototype computer program designed to facilitate the building and maintenance of a rule-based program which performs childhood immunization forecasting. An immunization forecasting program takes as input a child's immunization history and produces recommendations as to which vaccinations are due and which should be scheduled next. A significant amount of the knowledge required for immunization forecasting can be expressed in tabular form, including the parameters that indicate the minimum age when each dose may be given and the minimum intervals between doses. The choice of which of these sets of parameters apply to a particular case depends upon additional clinical logic. To perform forecasting, this logic must be applied in three temporal contexts: (1) a dose is due now, (2) a dose is not yet due, and (3) a dose must be scheduled to follow a dose which is due now. Building and maintaining this logic by hand is a formidable challenge. IMM/Def demonstrates how this task can be simplified by first defining immunization "definition logic" which can be automatically translated into if-then rules for each of the three contexts. The approach has been applied successfully to the six childhood vaccination series which are routinely administered. A key advantage is that IMM/Def allows one to have two specifications of the logic that can be examined independently and that can be cross-checked to help assure completeness, consistency, and accuracy of the logic. The paper describes how IMM/Def performs its translation and discusses several design issues and lessons learned.
In 2 experiments we investigated trance logic, or the tolerance of logical incongruity, in age regression and hallucination. Experiment 1 tested 21 hypnotizable and 19 unhypnotizable subjects in an application of the real-simulating model of hypnosis. Experiment 2 tested 26 high and 19 low imagery ability subjects in an adaptation of the model to the imagination context. Subjects' experiences were investigated through the experiential analysis technique. More real than simulating subjects displayed trance logic during age regression, but they did not differ on the major measures of trance logic during hallucination. This pattern of responding occurred in both the hypnosis and the imagination contexts. Subjects' comments suggested that completeness of and belief in age regression or hallucination may play some role in trance logic. The importance of understanding trance logic from the subject's point of view is discussed.