PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Dynamic Programming”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42Linked to original sources
PubMed2005

Correspondence between spin-dynamic phases and pulse program phases of NMR spectrometers.

Spin state selective experiments have become very useful tools in solution NMR spectroscopy, particularly in the context of TROSY line narrowing. However, the practical implementation of such pulse sequences is frequently complicated by unexpected instrument behavior. Furthermore, a literal theoretical analysis of sequences published with specific phase settings can fail to rationalize such experiments and can seemingly contradict experimental findings. In this communication, we develop a practical approach to this ostensible paradox. Spin-dynamic design, rationalization, and simulation of NMR pulse sequences, as well as their confident and reliable implementation across current spectrometer hardware platforms, require precise understanding of the underlying nutation axis conventions. While currently often approached empirically, we demonstrate with a simple but general pulse program how to uncover these correspondences a priori in the general case. From this, we deduce a correspondence table between the spin-dynamic phases used in NMR theory and simulation on the one hand and pulse program phases of current commercial spectrometers on the other. As a practical application of these results, we analyze implementations of the original (1)H-(15)N TROSY experiment and illustrate how steady-state magnetization can be predictably, rather than empirically, added to a desired component. We show why and under which circumstances a literal adoption of phases from published sequences can lead to incorrect results. We suggest that pulse sequences should be consistently given with spin-dynamically correct (physical) phases, rather than in spectrometer-specific (software) syntax.

Carbon Isotopes↗
PubMed2005

Brownian dynamics simulations of the self- and collective rotational diffusion coefficients of rigid long thin rods.

Recently a microscopic theory for the dynamics of suspensions of long thin rigid rods was presented, confirming and expanding the well-known theory by Doi and Edwards [The Theory of Polymer Dynamics (Clarendon, Oxford, 1986)] and Kuzuu [J. Phys. Soc. Jpn. 52, 3486 (1983)]. Here this theory is put to the test by comparing it against computer simulations. A Brownian dynamics simulation program was developed to follow the dynamics of the rods, with a length over a diameter ratio of 60, on the Smoluchowski time scale. The model accounts for excluded volume interactions between rods, but neglects hydrodynamic interactions. The self-rotational diffusion coefficients D(r)(phi) of the rods were calculated by standard methods and by a new, more efficient method based on calculating average restoring torques. Collective decay of orientational order was calculated by means of equilibrium and nonequilibrium simulations. Our results show that, for the currently accessible volume fractions, the decay times in both cases are virtually identical. Moreover, the observed decay of diffusion coefficients with volume fraction is much quicker than predicted by the theory, which is attributed to an oversimplification of dynamic correlations in the theory.

Journal Article↗
PubMed1990

Dynamic training and circulating levels of corticotropin-releasing factor, beta-lipotropin and beta-endorphin in rheumatoid arthritis.

The study aimed at evaluating the effects of a dynamic training program on circulating levels of corticotropin-releasing factor (CRF), beta-lipotropin (beta-LPH), and beta-endorphin (beta-EP) in 8 patients (5 females and 3 males, aged 39-65 years) with classical/definite rheumatoid arthritis (RA). Blood samples were collected immediately before, in the middle of, and after a 6-week high-intensity training period as well as after a subsequent 1-year period of low-intensity training. In addition, baseline data were obtained 3 weeks before the start of the training program. Use of multivariate analyses of variance, and of analyses of variance of contrast variables, indicated a short-term effect of the high-intensity training program for beta-EP with increased levels (P less than 0.05) between the 3rd and the 6th weeks, no significant differences being obtained for CRF or beta-LPH here. Corresponding analyses with regard to the combined high and low-intensity training program revealed CRF (P less than 0.01), and beta-LPH (P less than 0.01) levels to increase over time, no long-term effect being found for beta-EP. Despite the intensity of the dynamic training program, no change was found in pain experience as measured on a visual analogue scale.

Adult↗
PubMed2006

Topological dynamics of holins in programmed bacterial lysis.

The fate of phage-infected bacteria is determined by the holin, a small membrane protein that triggers to disrupt the membrane at a programmed time, allowing a lysozyme to attack the cell wall. S(21)68, the holin of phage 21, has two transmembrane domains (TMDs) with a predicted N-in, C-in topology. Surprisingly, TMD1 of S(21)68 was found to be dispensable for function, to behave as a SAR ("signal-anchor-release") domain in exiting the membrane to the periplasm, and to engage in homotypic interactions in the soluble phase. The departure of TMD1 from the bilayer coincides with the lethal triggering of the holin and is accelerated by membrane depolarization. Basic residues added at the N terminus of S(21)68 prevent the escape of TMD1 to the periplasm and block hole formation by TMD2. Lysis thus depends on dynamic topology, in that removal of the inhibitory TMD1 from the bilayer frees TMD2 for programmed formation of lethal membrane lesions.

Amino Acid Sequence↗
PubMed2003

Disentangling the dynamic core: a research program for a neurodynamics at the large-scale.

My purpose in this paper is to sketch a research direction based on Francisco Varela's pioneering work in neurodynamics (see also Rudrauf et al. 2003, in this issue). Very early on he argued that the internal coherence of every mental-cognitive state lies in the global self-organization of the brain activities at the large-scale, constituting a fundamental pole of integration called here a "dynamic core". Recent neuroimaging evidence appears to broadly support this hypothesis and suggests that a global brain dynamics emerges at the large scale level from the cooperative interactions among widely distributed neuronal populations. Despite a growing body of evidence supporting this view, our understanding of these large-scale brain processes remains hampered by the lack of a theoretical language for expressing these complex behaviors in dynamical terms. In this paper, I propose a rough cartography of a comprehensive approach that offers a conceptual and mathematical framework to analyze spatio-temporal large-scale brain phenomena. I emphasize how these nonlinear methods can be applied, what property might be inferred from neuronal signals, and where one might productively proceed for the future. This paper is dedicated, with respect and affection, to the memory of Francisco Varela.

Brain↗
PubMed1999

Dynamic treatment of displaced proximal phalangeal fractures.

We report a splint system for a protected mobilization program (termed dynamic treatment) of proximal phalangeal fractures. This program can be used for nonoperative treatment or after operative treatment. Intra-articular fractures of the proximal phalanx at the metacarpophalangeal joint were included. The custom-molded 2-component thermoplastic splint allows motion of the proximal and distal interphalangeal joints. It was developed to allow bone healing and recovery of motion at the same time. We evaluated the clinical and radiologic results of a consecutive series of 48 displaced proximal phalangeal fractures in 45 patients who received dynamic treatment. Fracture consolidation was achieved in all patients and bone healing and recovery of full active motion was achieved simultaneously in all but 4 patients by 6 weeks. The advantage of this splint system is the variability of its application. The splint can be used both for nonsurgical and surgical management. It can be removed to change dressings and for radiologic evaluations. The period of dynamic treatment can be determined individually in each case.

Adult↗
PubMed2006

Placing the dynamics of syringe exchange programs in the United States.

Drawing upon the broader health, social, and political geography literature, this paper outlines a framework for considering place-based processes through which syringe exchange availability may be understood. It is argued that the geographic distribution of syringe exchange programs (SEPs) in the United States is linked to the social and political conditions of particular localities through three place characteristics: (1) structural constraints; (2) social and spatial distancing of injection drug users; and (3) localized action. Although SEPs remain controversial and face ongoing obstacles from the government, law enforcement and local communities, they continue to operate through the efforts of grassroots organizations and local activists. Action on this issue occurs locally, and the characteristics of place-based factors affect whether particular areas adopt SEPs.

Consumer Advocacy↗
PubMedDate not supplied

Co-production dynamics and time dollar programs in community-based child welfare initiatives for hard-to-serve youth and families.

Hard-to-serve youth and families residing in high-poverty communities often have multiple, interlocking needs. These needs necessitate complex service models. The complex model described in this article combines a unique approach to wraparound services with a coproduction framework and related theories. The model aims to improve outcomes for vulnerable youth and their families, simultaneously strengthening communities by employing residents and engaging participants in community service. Examples derived from current pilot projects illustrate co-production's importance for other child welfare initiatives.

Child↗
PubMed1996

MDMovie: a molecular dynamics viewing tool.

The graphics program MDMovie (Molecular Dynamics Movie), written in C using IRIS GL graphics library calls, is designed to facilitate the visualization and interpretation of empirical force field data. MDMovie was created and initially adapted in accord with the needs of physical chemists and thereafter became an expandable analysis tool. Capabilities include the display of chemical structure, animation of molecular dynamics and Monte Carlo trajectories, and the visual representation of various vector and scalar dynamical properties. In addition to being a research tool, MDMovie has features for creating presentation videos and hardcopy output. A library is also available for linking to Fortran simulation codes running on a remote machine and connecting to MDMovie via a socket connection. MDMovie continues to be an ongoing research project and new features are actively being added in collaboration with various research groups. Future plans include porting to OpenGL and the design of an XII-based user interface.

Computer Graphics↗
PubMed1990

Muscle function in rheumatoid arthritis. Assessment and training.

The conclusions can be summarized as follows: experienced problems of muscle function were reported in about 80% of RA and OA patients for whom there was involvement of large joints of the lower extremities; RA and OA patients did not differ as to experienced problems of muscle strength, endurance and balance/coordination; problems of muscle function were correlated with functional tests of muscle strength but not with those of endurance and balance/coordination; problems of muscle strength were found to correlate with LE-ADL, whereas problems of endurance and balance/coordination were not found to correlate with the latter; the translated and slightly modified version of the HAQ questionnaire appeared to possess a high degree of reliability and validity in assessing disability in patients with RA under Swedish conditions; a quantitative battery of tests for the evaluation of standing balance on a computerized force platform was found to be satisfactorily reliable and to correlate in healthy subjects with most of the functional tests employed; in healthy subjects, standing balance appeared to be related not only to age but also to sex, males and older age groups showing greater postural sway than females and persons of younger age groups; compared with healthy subjects, RA subjects showed significantly greater postural sway, differences being greatest for those tests representing a relatively high level of difficulty; dynamic training for six weeks appeared to provide RA patients with a greater increase in physical capacity of the lower extremities than did static training, the gains thus obtained still being present after an additional three-month period; the effectiveness of the dynamic training programs did not vary with the degree of supervision of training by a physiotherapist, i.e. of 12 visits or 4 being made at the health care centre; despite the intensity of the dynamic training-program employed with RA patients, no increase in pain experience or disease activity was found during the training-period; during short-term high-intensity training a significant increase in circulating beta-EP was found between the 3rd and 6th weeks of training, no increase in CRF and beta-LPH being present; following a long-term low-intensity training period, a significant increase of CRF and beta-LPH was found, no similar increase being noted for beta-EP.

Arthritis, Rheumatoid↗
PubMed1991

Rehabilitation and biomechanics.

In the area of rehabilitation and biomechanics, several articles divided into five categories, including therapeutic heat, foot and ankle orthotics, exercise in elderly arthritis patients, muscle strengthening in rheumatoid arthritis, and arthroplasty and immobilization are reviewed. Superficial heat was demonstrated to increase intra-articular temperature, and therefore, may be detrimental. On the other hand, local deep microwave hyperthermia appears to have potential therapeutic benefits. The role and effectiveness of foot orthotic devices are reviewed. The problem and treatment of forefoot varus is emphasized. A new technique of measuring subpedal pressure in the shoe is presented, demonstrating reduced foot pressures by certain types of footwear. Rheumatoid arthritis and osteoarthritis wee present in 23% of a nursing home population, but were a substantial factor for placement in only 15%. However, this group had higher pain scores, depended more on wheelchair use, and was more likely to have significant functional limitations. Exciting new data on strengthening the quadriceps in the frail elderly, whose mean age was 90.2 years, are reviewed. The relationship of quadriceps muscle strength and maximum voluntary strength as a function of age and gender and the effects of an endurance training program in 15 physically compromised nursing home residents is discussed. A static and a dynamic training program for rheumatoid arthritis patients were compared. The dynamic group significantly increased muscle strength, endurance, and aerobic capacity as compared to the static group, without any increase in disease activity. The results further showed that a home program was beneficial. Interesting data presented show that using a Cybex isokinetic dynamometer (Lumex, Bayshore, NY) test was reliable for normal control and for rheumatoid arthritis patients who were stronger.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMed1992

SQUID: a program for the analysis and display of data from crystallography and molecular dynamics.

SQUID is a flexible computer program that allows the analysis and display of molecular coordinates from crystallography, NMR, and molecular dynamics. The program can also display two-dimensional and three-dimensional data using many graph types, as well as perform array processing of data with numerous intrinsic functions. Graphics are based on the use of "move" and "draw" instructions, allowing easy development of new device drivers, including vector plotters.

Computer Graphics↗