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Identifying target populations for screening or not screening using logic regression.

Colorectal cancer remains a significant public health concern despite the fact that effective screening procedures exist and that the disease is treatable when detected at early stages. Numerous risk factors for colon cancer have been identified, but none are very predictive alone. We sought to determine whether there are certain combinations of risk factors that distinguish well between cases and controls, and that could be used to identify subjects at particularly high or low risk of the disease to target screening. Using data from the Seattle site of the Colorectal Cancer Family Registry, we fit logic regression models to combine risk factor information. Logic regression is a methodology that identifies subsets of the population, described by Boolean combinations of binary coded risk factors. This method is well suited to situations in which interactions between many variables result in differences in disease risk. We found that neither the logic regression models nor stepwise logistic regression models fit for comparison resulted in criteria that could be used to direct subjects to screening. However, we believe that our novel statistical approach could be useful in settings where risk factors do discriminate between cases and controls, and illustrate this with a simulated data set.

Adult↗

Construction and implementation of NMR quantum logic gates for two spin systems.

The implementation of small prototype quantum computers has been studied through ensemble quantum computing via NMR measurements. In such laboratory studies it is convenient to have access to a wide array of logic gates. Here a systematic approach to reduce the logic gate to an NMR pulse sequence is introduced. This approach views the truth table for a quantum logic operation as a permutation matrix that corresponds to a propagator for an NMR transition. This propagator is then used as the starting point for the derivation of a pulse sequence. Pulse sequences for all the permutations of a four level system are reported along with implementations of representative examples on a two spin-1/2 system, 13C-labeled chloroform.

Magnetic Resonance Spectroscopy↗

Implementing logic gates and the Deutsch-Jozsa quantum algorithm by two-dimensional NMR using spin- and transition-selective pulses.

Quantum logical operations using two-dimensional NMR have recently been described using the scalar coupling evolution technique [J. Chem. Phys. 109, 10603 (1998)]. In the present paper, we describe the implementation of quantum logical operations using two-dimensional NMR, with the help of spin- and transition-selective pulses. A number of logic gates are implemented using two and three qubits with one extra observer spin. Some many-in-one gates (or Portmanteau gates) are also implemented. Toffoli gate (or AND/NAND gate) and OR/NOR gates are implemented on three qubits. The Deutsch-Jozsa quantum algorithm for one and two qubits, using one extra work qubit, has also been implemented using spin- and transition-selective pulses after creating a coherent superposition state in the two-dimensional methodology.

Journal Article↗

The use of medical logic modules at LDS hospital.

The development of medical knowledge bases for use in a clinical information system (HELP) has been an ongoing goal at LDS Hospital in Salt Lake City, Utah, for the past 25 years. In building our medical knowledge base we felt the need to implement a decision support syntax which could capture the logic of our experts in a way that was not only executable, but also easily read and shared by others. During these 25 years we defined several simple syntaxes to express this medical logic. Our current approach is to cooperate with international standards groups (ASTM) and use the Arden Syntax for medical logic modules. We are working with the 3M Corporation in the joint development of an Arden Compiler for HELP. We plan to use the Arden Syntax initially to support our alert/reminder system and computerized management protocols.

Artificial Intelligence↗

Structured approach in PLC (programmable logic controller) programming for water/wastewater applications.

This paper describes a methodology for efficient implementation of PLC programming for water/wastewater applications. The PLC was interfaced with a supervisory host computer which used touch screen equipped color monitors as operator interfaces. PLC ladder logic had to be designed to process real-world hardwired I/O as well as the I/O received from the host computer and/or touch screens, via a communications link. Standard "templates" of PLC networks were developed for (a) pump controls including provision for touch screen I/O; (b) PID control; (c) alarms; (d) motor run times; (e) square root extraction; (f) signal conversion, and (g) flow totalization. All logic was implemented using the standard templates. This structured approach led to efficient implementation, easy debugging/start-up, and easy to read uniform ladder logic.

Computer Systems↗

Logical elements in living cells.

Recognition processes with enhanced accuracy (as performed by structures like enzymes or ribosomes) are investigated using elementary ideas of statistical mechanics and related concepts of thermodynamics. The analysis starts from a formal definition of recognition and provides a correspondence with appropriate physical properties of the macromolecular logical elements. Transitions of the recognizing system between different modifications are a necessary feature of a more exacting recognition process. Rearrangement steps provide the process with higher accuracy by performing two physical operations: (1) rearranging the phase space of the system so that the "correct" states be better separated from the "wrong" states and the probability of occupation of the "correct" states be enhanced, (2) directing the process toward the more favourable modifications thus formed. Both operations are related to changes in the physical properties of the recognizing system. These changes can be expressed as differences of macromolecular Gibbs energy levels; if ligand binding or release participate in a step, directivity of the step depends also on the actual chemical potentials of the ligands in solution. The two operations just mentioned resemble two basic operations known to be necessary in electronic digital networks: directivity of control and signal standardization. An analysis of the entire reaction catalysed by a macromolecular logical element takes into account the requirements imposed by the logical functions as well as the need that the chemical potential of the product be not restricted to very low values. To satisfy these conditions, the reaction must be supported by a so-called non-specific reaction, usually implemented by the cleavage reaction of a nucleoside triphosphate.

Catalysis↗

Towards a logical analysis of the immune response.

We present a new way to conceive, formalize and analyse models of the immune network. The models proposed are minimal ones, based essentially on the well-established negative feedback loop between helper and suppressor T cells. The occurrence of T-T interactions in both helper and suppressor circuits. These T-T interactions are represented here by autocatalytic feedback loops on TH and TS. The fact that immature B cells are sensitive to negative signaling, as was originally suggested by Lederberg (1959). There is a functional inactivation of immature B cells encountering antigen or anti-idiotypic antibody. This prevents further differentiation to a stage where the B cells become fully responsive. We describe the role of a logical method in the generation and analysis of the models, and the complementarity between this logical method and the more classical description by continuous differential equations. Logical analysis and numerical simulations of the differential equations show that the emerging model accounts for, the occurrence of multiple steady states (a virgin state, a memory state and a non-responsive state) in the absence of antigen, the kinetics of primary and secondary responses, high dose paralysis, low dose of paralysis. Its fit with real situations is surprisingly good for a model of this simplicity. Nevertheless, we give it as an example of what can now be done in the field rather than as a stable model.

Antibody Formation↗

Identification of all steady states in large networks by logical analysis.

The goal of generalized logical analysis is to model complex biological systems, especially so-called regulatory systems, such as genetic networks. This theory is mainly characterized by its capacity to find all the steady states of a given system and the functional positive and negative circuits, which generate multistationarity and a cycle in the state sequence graph, respectively. So far, this has been achieved by exhaustive enumeration, which severely limits the size of the systems that can be analysed. In this paper, we introduce a mathematical function, called image function, which allows the calculation of the value of the logical parameter associated with a logical variable depending on the state of the system. Thus the state table of the system is represented analytically. We then show how all steady states can be derived as solutions to a system of steady-state equations. Constraint programming, a recent method for solving constraint satisfaction problems, is applied for that purpose. To illustrate the potential of our approach, we present results from computer experiments carried out on very large randomly-generated systems (graphs) with hundreds, or even thousands, of interacting components, and show that these systems can be solved using moderate computing time. Moreover, we illustrate the approach through two published applications, one of which concerns the computation times of all steady states for a large genetic network.

Arabidopsis↗

Symbolic logic analysis of congenital heart disease.

In identifying the primary, genetic or environmental event in human cardiac malformations, it is desirable to separate out the apparently secondary lesions. We have employed the general principle that multiple cardiac lesions within a single patient may often represent a pathogenetic process in which one primary event gives rise to a sequence of secondary lesions. The mechanical paradigm of cardiogenesis suggests that abnormal primary lesions may give rise to secondary lesions through altered blood flow or pressure relations, if the secondary structure normally appears later and represents a reasonable tissue response to altered mechanics. Symbolic logic is a mathematical method in which descriptive statements are placed in formal relation to one another and their logical consequences are deduced. Using the mechanical paradigm as a technique of hypothesis generation and symbolic logic as a technique of hypothesis testing, we have analyzed the following malformation complexes in large series of autopsied patients: coarctation of the aorta, tetralogy of Fallot, arterious malformation, interrupted aortic arch, and semilunar valve malformations.

Aortic Coarctation↗

A logic model framework for community nutrition education.

Logic models are a practical method for systematically collecting impact data for community nutrition efforts, such as the Food Stamp Nutrition Education program. This report describes the process used to develop and test the Community Nutrition Education Logic Model and the results of a pilot study to determine whether national evaluation data could be captured without losing flexibility of programming and evaluation at the state level. The objectives were to develop an evaluation framework based on the Logic Model to include dietary quality, food safety, food security, and shopping behavior/food resource management and to develop a training mechanism for use. The portability feature of the model should allow application to a variety of community education programs.

Consumer Product Safety↗

A logical functional analysis of reinforcement-based disorders: alcoholism and pedophilia.

This article discusses a nomothetic functional strategy, termed logical functional analysis, as an approach to the refinement of the structural diagnostic categories of the Diagnostic and Statistical Manual of Mental Disorders (e.g., 4th ed.; DSM-IV; American Psychiatric Association, 1994). As heterogeneous diagnostic categories are more the norm than the exception in the DSM-IV, an argument is made for the identification of homogenous subgroups within diagnostic classes based on functional principles. Outlines of a logical functional analysis for 2 reinforcement-based disorders, alcoholism and pedophilia, are presented. The outlines show how topographically similar behavior patterns can serve different functions that are important to consider when making treatment decisions. The logical functional analysis is a strategy that helps practitioners to identify motivational conditions, antecedents, consequences, and concomitant behavioral repertoires associated with a given disorder. It also provides guidance for the selection of intervention strategies.

Alcoholism↗

Fuzzy logic applications.

Fuzzy logic is a modeling method well suited for the control of complex and non-linear systems. This paper illustrates some of the power of fuzzy logic through a simple control example. For the analytical chemist, fuzzy logic incorporates imprecision from measurement noise as well as from linguistic process descriptions to produce operational control systems.

Journal Article↗

Logic gates using high Rydberg states.

Connected logic gates can be operated on the levels of one molecule by making use of the special properties of high Rydberg states. Explicit experimental results for the NO molecule are provided as an example. A number of other options, including that of several gates concatenated so as to operate as a full adder, are discussed. Specific properties of high Rydberg states that are used are: their autoionization is delayed so that they can be distinguished from direct multiphoton ionization, during their long life such states also can decay by energy transfer to the molecular core in a way that can be controlled by the judicious application of very weak external electrical fields, and the Rydberg states can be detected by the application of an ionizing electrical field. The combination of two (or three) color photons with and without external weak fields allows the construction of quite elaborate logic circuit diagrams and shows that taking advantage of the different intramolecular dynamics of levels that differ by their excitation enables the compounding of logic operations on one molecular frame.

Journal Article↗

Estimates of interrater reliability for the Logical Memory subtest of the Wechsler Memory Scale-Revised.

This study was undertaken to investigate the interrater reliability of the Logical Memory subtest of the Wechsler Memory Scale-Revised under two conditions. In the first condition, raters applied standard WMS-R scoring for Logical Memory to written transcripts of subjects' recall. In the second condition, raters were instructed to listen to and record subjects' responses before applying the scoring criteria. Responses from 32 undergraduate university students were scored by three independent judges with professional experience in WMS-R use. Responses were analysed to generate estimates of interrater reliability that could be compared to those provided in the WMS-R manual (Wechsler, 1987). The results provide independent confirmation that the standard scoring procedure for Logical Memory is highly reliable when applied by trained clinicians.

Adult↗

Interhemispheric asymmetry of event-related fields concerned with logical processing during auditory oddball stimulation.

This study investigated the cortex during logical processing of auditory information using a 122-channel dc-SQUID gradiometer. The experimental task was designed to require a simple logical decision prior to counting rare paired tones, which consisted of two different pitches and were presented to separate ears. Among six subjects, left and right predominant dipolar activity was observed in three subjects each. When the dipolar sources were superimposed on MR images, the inferior region of the supramarginal gyrus showed activation, suggesting that logical processing occurred in the association cortex but not in the auditory cortex. We propose a modified cognitive sequence model in which auditory information processed in Heschl's gyri is transmitted to the supramarginal gyrus to commence automatic detection processing.

Acoustic Stimulation↗

Ocular surface reconstruction in LOGIC syndrome by amniotic membrane transplantation.

PURPOSE: To determine whether preserved amniotic membrane can be used to reconstruct the ocular surface after excision of the invading granulation material typical of LOGIC syndrome (laryngeal and ocular granulation tissue in children from the Indian subcontinent). METHODS: Granulation tissue was dissected and excised from both eyes of a 10-year-old boy with LOGIC syndrome. This procedure was followed by coverage of the corneal, scleral, and subtarsal regions of each eye with amniotic membrane, which had been stored for 6 months at -70 degrees C. RESULTS: Initial 2.5-month follow up demonstrated complete disappearance of granulation tissue. The fornices were patent, there was no recurrence of symblepharon, ocular inflammation was suppressed, and the patient reported markedly increased comfort. Both eyelids remained ptotic because of levator muscle atrophy secondary to many years of inability to open either eye. No residual scarring or evidence of granulation tissue was observed in that period. The 10-month follow up demonstrated limited recurrence, particularly where there was an intraoperative break in the amniotic membrane. CONCLUSIONS: After 24 operations to treat the ocular complications induced by LOGIC syndrome, amniotic membrane transplantation was the first effective treatment. In the early follow up period (2-3 months), there was complete cessation of the proliferation of granulation tissue and reepithelialization of the corneal surface. Longer follow up (10 months) demonstrated limited recurrence, which will require retreatment.

Amnion↗

Creating a successful clinical extern program using a program planning logic model.

Creative programs, such as a clinical externship for employment of nursing students, can be successfully created using a program planning logic model. The planning, implementation, and evaluation components of a clinical extern program will be demonstrated using logic model. The use of the logic model was instrumental to the success of the program.

Attitude of Health Personnel↗

Measuring the impact of a Web-based data query system: the logic model as a tool in the evaluation process.

A review of program evaluation perspectives, including the concept of a logic model and its applicability to the evaluation of Web-based data query systems (WDQSs), is presented. A logic model is used to flesh out evaluation components of a WDQS, including inputs, constraints, program activities, program outputs, and outcomes. For each component, a list of potential items is presented for inclusion in the model, along with examples of initial, intermediate, and ultimate outcomes for a WDQS. Program evaluation is a process that is important to conduct both early in WDQS development to promote clarity of its vision and objectives and throughout the course of the WDQS implementation and maintenance to ensure that its objectives are being met. Should the WDQS not be producing desirable results, the logic model provides a road map for understanding which activities are not meeting the WDQS's objectives so that the course of WDQS development, implementation, and maintenance may be altered to improve the probability of reaching desirable outcomes.

Internet↗