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Results for “Utility Theory”

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PubMed1996

Spike detection. I. Correlation and reliability of human experts.

A panel of 5 experienced electroencephalographers detected spikes in EEG trials from 40 epilepsy patients and 10 control subjects. 1952 spikes were detected, and detailed attribute scores were recorded. Statistics from the theory of measurement error are utilized to quantify the reliability and difficulty of the study. An extension of the Pearson correlation coefficient, called the detection correlation coefficient, is derived and used in recognition of the fact that readers agree on numerous non-spike regions. Spike perception is modeled with both dichotomous and continuous values. as expected, the study reliability is higher when using the continuous values. Standard sensitivity and specificity definitions are extended and applied to continuous-valued spike perception. A database of "panel scores" was created from the 5 reader scorings by merging spikes within 75 msec on each side. The average inter-reader correlation is 0.79 with a corresponding reliability of 0.95. Average spike attributes are calculated, and the resulting database can serve as a "gold standard" for testing computer algorithms or other readers.

Action Potentials↗

PubMed1986

Homodyne interferometer for basilar membrane measurements.

Techniques available for measuring the mechanical response of the inner ear are compared. These include capacitive probe, Mössbauer and interferometric methods. The theory of a homodyne interferometer utilized for inner ear measurements is given. Experimental apparatus built to test the interferometer performance is described. Experimental results show that the measuring system can detect vibrations as low as 3 X 10(-12) cm. Its frequency response is flat within 1 dB from 0.1 to 40 kHz. It has a linear dynamic range of over 90 dB. Immunity of the interferometer to various disturbances is demonstrated.

Basilar Membrane↗

PubMed2006

Constructing safety: system designs, system effects, and the play of heterogeneous interests in a behavioral health care setting.

OBJECTIVE: This paper considers the utility of actor-network theory as a basis for uncovering the mutual interdependencies between system design and system impact in an evolving project, and for exploring the implications that these interdependencies hold for the production of safety in behavioral health care. METHODS: Drawing on a field study of a systems project in a human-services firm, the paper applies key concepts from actor-network theory in the analysis of a design crisis that emerged during the course of the project. RESULTS: Actor-network theory provides a compelling framework in this situation for identifying the diverse interests involved, revealing their complex interactions, and illuminating the importance of the emerging system as an organizational actor in its own right. CONCLUSION: Actor-network theory shows promise for use in other analyses concerned with the role of information technology in the construction of safety in health care settings.

Behavioral Medicine↗

PubMed2005

Knowledge-based reconstruction of random porous media.

An evolutionary optimization technique is used to reconstruct digitized material models of 300(3) nm3 size for mesoporous two-phase systems. The models are adapted to the two-point probability (TPP) and to a volume-based pore-size distribution (PSD) which were derived from SANS and adsorption experiments and which carry statistical information about morphology and topology of the pore system. To avoid extreme update-costs, the bulk of mutations are assessed by means of a suitable approximation of the PSD; it is demonstrated that a sporadic insertion of the PSD suffices to drive the algorithm towards satisfactory models in acceptable time. Our approach is knowledge-based in the sense that (i) the mutations are restricted to expedient exchanges of phase-voxels by a heuristic rule, and (ii) the sporadic calculation of the PSD from the current state of the model, in essence, provides an efficient self-control for the evolutionary process. We applied the method to reconstruct periodic models of the xerogel Gelsil 200. Such reconstructs of real mesoporous solids could be utilized, for instance, to verify theories of adsorption and capillary condensation.

Journal Article↗

PubMed2005

Cerebral glucose metabolism in adults with early treated classic phenylketonuria.

Classic phenylketonuria (PKU) is characterized by severe mental retardation in untreated individuals and mild neurocognitive abnormalities in some early treated adults. The exact biochemical mechanisms underlying this neurotoxicity remain undetermined. Several theories implicate abnormal cerebral energy utilization and alterations in biochemical pathways that involve glucose metabolism. This pilot study was undertaken to investigate whether 18F-deoxyglucose positron emission tomography (PET) is an effective tool to study cerebral glucose metabolism in early treated PKU. After PET coregistration with SPGR MRI, relative glucose metabolic rates (rGMR) at the center of standard atlas positions was determined. Repeated measures MANOVA was used to assess regional metabolic differences, which were then correlated with age-specific and day-of-scan plasma phenylalanine and age. Patients with PKU in comparison to controls had decreased rGMR in cortical regions including the prefrontal, somatosensory, and visual cortices, and increased activity in subcortical regions including the striatum and limbic system. Day-of-scan phenylalanine correlated with abnormal activity in subcortical structures, and older age was associated with decreased activity in the prefrontal and visual cortices. The clinical significance of these abnormalities of glucose metabolism in specific areas of the brain remains unknown.

Adult↗

PubMed2001

Optimal patterns for suturing wounds of complex shapes to foster healing.

Stress is one of the many biological factors that plays an important role in wound healing. It is therefore essential to analyze stresses around the wound closure theoretically, especially when no invasive/noninvasive technique to measure stress directly is available. The objective of this paper is to determine the regions of high stresses and the optimal pattern of suturing wounds of complex shapes. It is hypothesized that the optimal pattern of suturing wounds is that pattern which will produce minimum principal stresses. The finite element method (FEM) employing the basic equations of elasticity theory for orthotropic materials is utilized to compute the principal stresses and displacements resulting from suturing fusiform, elliptical and triangular wounds in human abdominal skin. The optimal suturing pattern for the triangular wound is determined. The average stress indices for varying suturing density are also determined which can provide useful clinical information for the surgeon. Since regions of high stresses in surgical closures produce adverse affects on healing and scar production, this work of predicting areas of high stresses is useful in indicating regions of slow healing in wounds.

Compressive Strength↗

PubMed2000

Experimental manipulation of a unique cue in Pavlovian SCR conditioning with humans.

We report two experiments on positive and negative patterning in human skin conductance response (SCR) conditioning with a manipulable unique cue. In experiment 1 flashing red lights, arrayed horizontally, were used as elements and apparent movement was used as additional (unique) cue when the elements were presented in compound. Positive and negative patternings were both acquired readily, and positive patterning transferred to new stimuli (green lights, vertically arrayed). The unique cue did not influence these outcomes. Experiment 2 examined only positive patterning, using a more conventional unique cue, a visual frame that surrounded the letter stimuli on compound trials but not on element trials. The unique cue again facilitated neither acquisition nor transfer. These results do not support either the unique cue extension of the Rescorla-Wagner theory or configural theories. Human participants seem to utilize 'size' or 'number' or some other abstract feature in preference to available concrete stimuli.

Adult↗

PubMedDate not supplied

Ethics and research priorities in academic administration.

Deans and directors of nursing education programs have primary responsibility for budgets even though different programs vary in the advising and recommending power given to committees. With research needing greater emphasis, especially in schools with graduate programs, and budgets at all levels facing minimal increases or cutbacks, nursing deans are faced with difficult decisions in securing and allocating monies for research. Many faculty view decisions and allocations only at the micro level of who gets money for what and do not consider these decisions from the perspective of how they are influenced by such macro-level considerations as restructuring of health care, the downsizing of educational programs, and the strategic plans of their own institution and granting agencies. In this article an attempt was made to consider both the macro and micro levels and to select from several ethical theories such principles as caring, utility, justice, and faithfulness to illustrate how the decisions can be guided by ethical principles. Ethics of caring can be seen as a guide in research development. Utility is about the only justification for downsizing and restructuring. The expectations of higher administration, faculty, students, and alumni may create dilemmas in regard to faithfulness. Distributive justice provides guidance for the distribution of scarce resources.

Ethics, Nursing↗

PubMed2006

Medium effects on the decarboxylation of a biotin model in pure and mixed solvents from QM/MM simulations.

The decarboxylation of imidazolidin-2-one-1-carboxylate anion 2 has been investigated via combined quantum and statistical mechanics methodology. Monte Carlo statistical mechanics simulations utilizing free-energy perturbation theory and PDDG/PM3 for the QM method yielded free-energy profiles for the reaction in water, methanol, acetonitrile, and mixed solvents. The results for free energies of activation are uniformly in close accord with experimental data and reflect large rate accelerations in progressing from protic to dipolar aprotic media. Structural and energetic analyses confirm that the rate retardation in protic solvents comes from loss of hydrogen bonding in progressing from the carboxylate anion 2 to the more charge-delocalized transition state (TS). The structure of the TS is found to be significantly affected by the reaction medium; it occurs at a 0.2-A shorter C-N separation in protic solvents than in acetonitrile. Characterization of the hydrogen bonding for 2 and the TS also provided insights for design of decarboxylase catalysts, namely, it is desirable to have three hydrogen-bond donating groups positioned to interact with the ureido oxygen along with two hydrogen-bond donors positioned to interact with the ureido nitrogen of the breaking C-N bond.

Acetonitriles↗

PubMed2005

Removing critical errors for DFT applications to transition-metal nanoclusters: correct ground-state structures of Ru clusters.

As ruthenium plays an important role in heterogeneous catalysis, understanding the structural and electronic properties of Ru clusters is crucial to advancement of technology. Because of its efficiency, density functional theory (DFT) calculations are often utilized in nanoscience, but careful validation is necessary. Recently, small, nonmetallic Ru(n) clusters were reported by Zhang et al. [J. Phys. Chem. B 2004, 108, 2140] to form unusual square and cubic ground-state structures within DFT by treating the exchange-correlation (XC) functional at the level of general-gradient-corrected approximation (GGA). For such clusters, we show that the calculated, energetically preferred structures are sensitive to which XC functional is used and whether relativistic effects are included. We find that a hybrid XC functional with partially exact exchange, such as PBE0, corrects the Ru2 magnetic moment, bond length, and dissociation energy in agreement with experiment and high-level quantum chemistry calculations and changes the Ru4 ground-state structure to a tetrahedron, instead of a square. The change in structural preference is explained by the corrections to the electronic structure of a Ru atom, where the relative position of majority spin s level is shifted with respect to e(g) levels. We also find that standard nonrelativistic DFT-GGA gives similar results to relativistic DFT-PBE0, i.e., relative shifting of s level, but not for the right reasons. Our results again stress the need to validate an XC functional before application to transition-metal nanoclusters.

Journal Article↗

PubMed2006

Conformational stability from temperature-dependent fourier transform infrared spectra of noble gas solutions, r0 structural parameters, and barriers to internal rotation for ethylamine.

Variable temperature (-55 to -145 degrees C) studies of the infrared spectra (3500 to 100 cm(-1)) of ethylamine, CH(3)CH(2)NH(2), dissolved in liquid krypton and/or xenon have been recorded. From these data, the enthalpy differences have been determined to be 54 +/- 4 cm(-1) (0.65 +/- 0.05 kJ/mol), with the trans conformer (methyl group relative to the lone pair of electrons on nitrogen) being the more stable form. It is estimated that there is 61 +/- 1% of the doubly degenerate gauche form present at ambient temperature. The conformational energetics have been calculated with the Møller-Plesset perturbation method to the second order (MP2(full)) and the fourth order (MP4(SDTQ)) as well as with density functional theory by the B3LYP method utilizing a variety of basis sets. Basis sets with diffuse functions lead to incorrect prediction of the conformational stability. On the basis of the frequencies of the torsional transitions along with the determined experimental enthalpy difference and gauche dihedral angle, the potential function governing conformational interchange has been obtained, and the determined Fourier cosine coefficients are V(1) = -207 +/- 48, V(2) = 320 +/- 67, V(3) = 1072 +/- 25, V(4) = 55 +/- 11, and V(5) = -96 +/- 28 cm(-1), with a trans-to-gauche barrier of 1286 cm(-1), and a gauche-to-gauche barrier of 715 cm(-1). The 3-fold methyl rotational barriers have been determined to be 1241 +/- 4 and 1281 +/- 10 cm(-1) for the gauche and trans conformers, respectively. By utilizing the previously reported microwave rotational constants combined with the structural parameters predicted at the MP2(full)/6-311+ G(d,p) level, adjusted r(0) structural parameters have been obtained. A complete vibrational assignment is given for the trans conformer, which is supported by normal coordinate calculations utilizing scaled force constants from ab initio B3LYP/6-311++G(3df,3pd) calculations. Proposed assignments are also made for the fundamentals of the gauche conformer. The results of these spectroscopic and theoretical studies are discussed and compared to the corresponding results for similar molecules.

Ethylamines↗

PubMed2000

Coping with domestic violence: control attributions, dysphoria, and hopelessness.

We investigated the influence of control judgments and coping style on emotional reactions to domestic violence utilizing the framework of hopelessness theory. We assessed abuse severity, control attributions, coping, dysphoric symptoms, and hopelessness in 70 battered women recruited from 12 domestic violence agencies. Respondents reported dysphoria but not hopelessness. Increased reports of dysphoria were associated with higher levels of self-blame and avoidance coping and lower levels of problem-focused coping. Increased problem-focused coping was associated with decreased hopelessness. Perceived control over current abuse was not related to dysphoria. High expectations for control over future events were associated with decreased dysphoria. We discuss our results in terms of their application to attributional accounts of emotional reactions to battering.

Adaptation, Psychological↗

PubMed1997

Joint attention and early social communication: implications for research on intervention with autism.

Highly structured, intensive early intervention may lead to significant developmental gains for many children with autism. However, a clear understanding of early intervention effects may currently be hampered by a lack of precision in outcome measurement. To improve the precision and sensitivity of outcome assessment it may be useful to integrate research on the nature of the social disturbance of autism with research on early intervention. In this regard, it may be that measures of nonverbal social communication skills are especially important in the study of preschool intervention programs. This is because these measures appear to tap into a cardinal component of the early social disturbance of autism, and because these measures have been directly related to neurological, cognitive, and affective processes that may play a role in autism. The research and theory that support the potential utility of these types of measures for early intervention research are reviewed. Examples are provided to illustrate how these types of measures may assist in addressing current issues and hypotheses about early intervention with autism including the "recovery hypothesis," the "pivotal skill hypothesis," and the relative effectiveness of discrete trial versus incidental learning approaches to early intervention. A cybernetic model of autism is also briefly described in an effort to better understand one potential component of early psychoeducational treatment effects with children with autism.

Age Factors↗

PubMed1980

Vanadate inhibition of auxin-enhanced H secretion and elongation in pea epicotyls and oat coleoptiles.

In experiments carried out to investigate the acid secretion theory of auxin action, we utilized sodium orthovanadate, an agent found to be a selective inhibitor of a plasma membrane-associated H(+)-pumping ATPase in Neurospora [Bowman, B. J. & Slayman, C. W. (1979) J. Biol. Chem. 245, 2928-2934]. At 1 mM, vanadate inhibited auxin-enhanced medium acidification by pea epicotyl segments within 5 min, whether added 0.5 or 2.5 hr after auxin. Inhibition of acidification was total after 10-15 min but could be reversed within 10 min after vanadate removal. When given as a 40-min pretreatment, vanadate completely prevented any auxin-enhanced acidification. Vanadate inhibition of medium acidification by oat coleoptile segments was also total and reversible, but both inhibition and reversal occurred after longer lag times than in pea. Inhibitory effects of vanadate on elongation in pea and oat tissue closely paralleled its effects on acidification, and the inhibitory effect of vanadate on elongation could be reversed by an acidic buffer. Vanadate did not inhibit respiration or protein synthesis in pea epicotyl segments, although it strongly inhibited L-[(14)C]leucine uptake. These results indicate the importance of cell wall acidification for short- and long-term auxin-enhanced growth and suggest the participation in wall acidification of a plasma membrane-associated ATPase acting as an H(+) pump.

Journal Article↗

PubMed2006

The neuroscience of observing consciousness & mirror neurons in therapeutic hypnosis.

Neuroscience documents the activity of "mirror neurons" in the human brain as a mechanism whereby we experience empathy and recognize the intentions of others by observing their behavior and automatically matching their brain activity. This neural basis of empathy finds support in research on dysfunctions in the mirror systems of humans with autism and fMRI research on normal subjects designed to assess intentionality, emotions, and complex cognition. Such empathy research now appears to be consistent with the historical and research literature on hypnotic induction, rapport, and many of the classical phenomena of suggestion. A preliminary outline of how mirror neurons may function as a rapport zone mediating between observing consciousness, the gene expression/protein synthesis cycle, and brain plasticity in therapeutic hypnosis and psychosomatic medicine is proposed. Brain plasticity is generalized in the theory, research, and practice of utilizing mirror neurons as an explanatory framework in developing and training new skill sets for facilitating an activity-dependent approach to creative problem solving, mind-body healing, and rehabilitation with therapeutic hypnosis.

Brain↗

PubMed1995

Implications of mind-body theory for integration in psychiatry.

Recently, several authors have called for an integration of philosophy, psychology, and neuroscience regarding the mind-brain problem (Brothers 1989; Cooper 1985; Hundert 1989). In this essay I review two philosophical theories of mind that lead to very different conclusions regarding integration. Reductionist materialism is the theory that currently has the widest acceptance. Unity theory, a less familiar theory, may present the most plausible alternative to reductionism currently available. Numerous examples from the psychiatric literature are used to illustrate the challenge that faces each of these theories. Critical evaluation of how they meet the challenge, particularly in accounting for apparent psychosomatic causation, shows the strengths and weaknesses of each theory, particularly regarding their clinical utility in psychiatry.

Brain↗

PubMed2003

Assessing response profiles from incomplete longitudinal clinical trial data under regulatory considerations.

Treatment effects are often evaluated by comparing change over time in outcome measures. However, valid analyses of longitudinal data can be problematic, particularly when some data are missing for reasons related to the outcome. In choosing the primary analysis for confirmatory clinical trials, regulatory agencies have for decades favored the last observation carried forward (LOCF) approach for imputing missing values. Many advances in statistical methodology, and also in our ability to implement those methods, have been made in recent years. The characteristics of data from acute phase clinical trials can be exploited to develop an appropriate analysis for assessing response profiles in a regulatory setting. These data characteristics and regulatory considerations will be reviewed. Approaches for handling missing data are compared along with options for modeling time effects and correlations between repeated measurements. Theory and empirical evidence are utilized to support the proposal that likelihood-based mixed-effects model repeated measures (MMRM) approaches, based on the missing at random assumption, provide superior control of Type I and Type II errors when compared with the traditional LOCF approach, which is based on the more restrictive missing completely at random assumption. It is further reasoned that in acute phase clinical trials, unstructured modeling of time trends and within-subject error correlations may be preferred.

Clinical Trials as Topic↗

PubMed2003

Robotic surgery: urologic implications.

Current medical robots have nothing in common with the anthropomorphic robots in science fiction classics. They are in fact, manipulators, working on a master-slave principle. Robots can be defined as "automatically controlled multitask manipulators, which are freely programmable in three or more spaces." The success of robots in surgery is based on their precision, lack of fatigue, and speed of action. This review describes the theory, advantages, disadvantages, and clinical utilization of mechanical and robotic arm systems to replace the second assistant and provide camera direction and stability during laparoscopic surgery. The Robotrac system (Aesculap, Burlingame, CA), the First Assistant (Leonard Medical Inc, Huntingdon Valley, PA), AESOP (Computer Motion, Goleta, CA), ZEUS (Computer Motion), and the da Vinci (Intuitive Surgical, Mountain View, CA) system are reviewed, as are simple mechanical-assist systems such as Omnitract (Minnesota Scientific, St. Paul, MN), Iron Intern (Automated Medical Products Corp., New York, NY), the Bookwalter retraction system (Codman , Somerville, NJ), the Surgassistant trade mark (Solos Endoscopy, Irvine, CA), the Trocar Sleeve Stabilizer (Richard Wolf Medical Instruments Corp., Rosemont, IL), and the Endoholder (Codman, Somerville, NJ).

Equipment Design↗