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Results for “Integrative interaction”

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At least 883 records · Page 49Linked to original sources

PubMed2001

Microscopic approach for the site distribution and thermodynamic properties of a single-component polymer subjected to an external field.

A microscopic statistical mechanics approach is proposed for a nonuniform single-component freely jointed tangential hard-sphere polymer in the framework of density-functional theory. The present approach avoids the use of single-chain simulation in the theory by treating bonding interaction on the basis of the properties of the Dirac delta function. The present excess free energy includes all terms of functional perturbative expansion around the uniform bulk fluid in the form of the Verlet-modified bridge function. The second-order direct correlation function of a uniform polymer melt as the input parameter is obtained by solving numerically the polymer-reference-interaction-site-model integral equation with the Percus-Yevick closure. Predictions of the present approach for such microscopic structural and thermodynamics properties as the site density distribution, the partition coefficient, and the adsorption isotherm near a hard wall or between two hard walls are compared with computer-simulation results and with those of previous theories. The comparison indicates that the present approach is more accurate than the previous integral equation theory and the most accurate Monte Carlo density-functional theories. The predicted oscillations of the medium-induced force between two hard walls immersed in polymer melts are consistent with the experimental results available in the literature. The relation of the present approach with self-consistent-field theory, as well as the differences between the two, are discussed.

Journal Article↗

PubMed2002

Simple weighted density functional approach to the structure of polymers at interfaces.

A simple weighted density functional approach is employed here for predicting the structure of polymers at interfaces where the polymer molecules are modeled as freely rotating fused-hard-sphere chains with fixed bond lengths and bond angles. The approach treats the ideal gas free energy functional exactly while the excess free energy functional is evaluated using a weighted density approximation. The weight function and the bulk fluid direct correlation function required in the theory are obtained using the Denton-Ashcroft recipe and the polymer reference interaction site model integral equation theory, respectively. The calculated density profiles are shown to be in good agreement with computer simulation results.

Journal Article↗

PubMed2004

Exactly solvable model of the BCS-BEC crossover.

We discuss an integrable model of interacting fermions in one dimension that allows a complete description of the crossover from a BCS- to a Bose-like superfluid. This model bridges the Gaudin-Yang model of attractive spin 1/2 fermions to the Lieb-Liniger model of repulsive bosons. Using a geometric resonance in the one-dimensional scattering length, the inverse coupling constant varies from -infinity to +infinity while the system evolves from a BCS-like state through a Tonks-Girardeau gas to a weakly interacting Bose gas of dimers. We study the ground state energy, the elementary density and spin excitations, and the correlation functions. An experimental realization with cold atoms of such a one-dimensional BCS-BEC crossover is proposed.

Journal Article↗

PubMed2005

Equivalence of Bose-Einstein condensation and symmetry breaking.

Based on a classic paper by Ginibre [Commun. Math. Phys. 8, 26 (1968)] it is shown that, whenever Bogoliubov's approximation, that is, the replacement of a(0) and a*(0) by complex numbers in the Hamiltonian, asymptotically yields the right pressure, it also implies the asymptotic equality of |a(0)|(2)/V and a*(0)a(0)/V in symmetry breaking fields, irrespective of the existence or absence of Bose-Einstein condensation. Because the former was proved by Ginibre to hold for absolutely integrable superstable pair interactions, the latter is equally valid in this case. Apart from Ginibre's work, our proof uses only a simple convexity inequality due to Griffiths.

Journal Article↗

PubMed2000

Three-dimensional modeling and visualization of the cochlea on the Internet.

Three-dimensional (3-D) modeling and visualization of the cochlea using the World Wide Web (WWW) is an effective way of sharing anatomic information for cochlear implantation over the Internet, particularly for morphometry-based research and resident training in otolaryngology and neuroradiology. In this paper, 3-D modeling, visualization, and animation techniques are integrated in an interactive and platform-independent manner and implemented over the WWW. Cohen's template shape with mean cross-sectional areas of the human cochlea is extended into a 3-D geometrical model. Also, spiral computer tomography data of a patient's cochlea is digitally segmented and geometrically represented. The cochlear electrode array is synthesized according to its specification. Then, cochlear implantation is animated with both idealized and real cochlear models. Insertion length, angular position, and characteristic frequency of individual electrodes are estimated online during the virtual insertion. The optimization of the processing parameters is done to demonstrate the feasibility of this technology for clinical applications.

Cochlea↗

PubMed1984

Participation in the medical consultation: the co-ordination of verbal and nonverbal behavior between the doctor and patient.

The following paper is concerned with the coordination of verbal and nonverbal behaviour by the doctor and patient in the medical consultation. It explores the relationship between the talk of the patient and the nonverbal behaviour of the doctor and demonstrates how the gaze direction of the doctor plays a crucial part in the articulation of an utterance by the patient. In examining a series of examples drawn from primary health care consultations, the analysis reveals how patients, or more generally speakers, use gestural activity to realign the gaze of their recipient(s) and encourage their participation in talk. In this fashion the paper addresses the problem of how the participants maintain a state of mutual involvement and sustain their integration within social interaction.

Behavior↗

PubMed2004

Primitive complement system of invertebrates.

Most components of the human complement system have unmistakable domain architectures, making evolutionary tracing feasible. In contrast to the major genes of the adaptive immune system, which are present only in jawed vertebrates, complement component genes with unique domain structures are present not only in jawed vertebrates but also in jawless fish and non-vertebrate deuterostomes. Recent progress in genome analysis in several eukaryotes, occupying the phylogenetically critical positions, showed that most individual domains found in the complement components are metazoa specific, being found both in deuterostomes and in protostomes but not in yeast or plant. However, unique domain architecture of complement components is not present in protostomes, suggesting that the complement system has been established in the deuterostome lineage not by invention of new domains but by innovation of unique combination of the pre-existing domains. The recently assembled Ciona intestinalis draft genome contained the most modular complement genes, except for factor I. However, some possible C. intestinalis complement components show critical structural divergence from the mammalian counterparts, casting doubt on their mutual interaction. Thus, another integrative step seems to have been required to establish the modern complement system of higher vertebrates.

Animals↗

PubMed1980

Manipulation: a negative element in care.

Manipulation is an integral factor in interaction. It can take either a positive or negative, constructive or destructive form. It can be either a conscious factor in the relationship or the external outcome of an unconscious need on the part of either person in the relationship. This compulsion to care can become very destructive and non-fulfilling for those involved. This compulsive need to care leads to stereotyped care, which, therefore, makes no allowance for the fact that, despite similarities, all men are different and individual, to be treated and cared for as such. Compulsive caring is no longer considering care as a partnership, a learning creative encounter, but a grasping, selfish act of a domineering, over-anxious person. The characteristics of 'the helping personality' are identified and their relevance to the discussion. It is argued that both carer and patient can manipulate or be manipulated, depending upon the extent of conformity to 'strong' and 'weak' positions within the patient-carer relationship, and personality characteristics of those involved. The importance of being aware of manipulative behaviour, its positive potential, and negative consequences is stressed: gaining awareness by considering the caring relationship in which one is involved.

Communication↗

PubMed2005

Human mast cell mediator cocktail excites neurons in human and guinea-pig enteric nervous system.

Neuroimmune interactions are an integral part of gut physiology and involved in the pathogenesis of inflammatory and functional bowel disorders. Mast cells and their mediators are important conveyors in the communication from the innate enteric immune system to the enteric nervous system (ENS). However, it is not known whether a mediator cocktail released from activated human mast cells affects neural activity in the ENS. We used the Multi-Site Optical Recording Technique to image single cell activity in guinea-pig and human ENS after application of a mast cell mediator cocktail (MCMC) that was released from isolated human intestinal mucosa mast cells stimulated by IgE-receptor cross-linking. Local application of MCMC onto individual ganglia evoked an excitatory response consisting of action potential discharge. This excitatory response occurred in 31%, 38% or 11% neurons of guinea-pig submucous plexus, human submucous plexus, or guinea-pig myenteric plexus, respectively. Compound action potentials from nerve fibres or fast excitatory synaptic inputs were not affected by MCMC. This study demonstrates immunoneural signalling in the human gut and revealed for the first time that an MCMC released from stimulated human intestinal mast cells induces excitatory actions in the human and guinea-pig ENS.

Animals↗

PubMed2006

Complex adjustments of photosynthetic potentials and internal diffusion conductance to current and previous light availabilities and leaf age in Mediterranean evergreen species Quercus ilex.

Mature non-senescent leaves of evergreen species become gradually shaded as new foliage develops and canopy expands, but the interactive effects of integrated light during leaf formation (Q(int)G), current light (Q(int)C) and leaf age on foliage photosynthetic competence are poorly understood. In Quercus ilex L., we measured the responses of leaf structural and physiological variables to Q(int)C and Q(int)G for four leaf age classes. Leaf aging resulted in increases in leaf dry mass per unit area (M(A)), and leaf dry to fresh mass ratio (D(F)) and decreases in N content per dry mass (N(M)). N content per area (N(A)) was independent of age, indicating that decreases in N(M) reflected dilution of leaf N because of accumulation of dry mass (NA = N(M) M(A)). M(A), D(F) and N(A) scaled positively with irradiance, whereas these age-specific correlations were stronger with leaf growth light than with current leaf light. Area-based maximum ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylase activity (V(cmax)A), capacity for photosynthetic electron transport (J(max)A) and the rate of non-photorespiratory respiration in light (R(d)A) were also positively associated with irradiance. Differently from leaf structural characteristics, for all data pooled, these relationships were stronger with current light with little differences among leaves of different age. Acclimation to current leaf light environment was achieved by light-dependent partitioning of N in rate-limiting proteins. Mass-based physiological activities decreased with increasing leaf age, reflecting dilution of leaf N and a larger fraction of non-photosynthetic N in older leaves. This resulted in age-dependent modification of leaf photosynthetic potentials versus N relationships. Internal diffusion conductance (g(m)) per unit area (g(m)A) increased curvilinearly with increasing irradiance for two youngest leaf age classes and was independent of light for older leaves. In contrast, g(m) per dry mass (g(m)M) was negatively associated with light in current-year leaves. Greater photosynthetic potentials and moderate changes in diffusion conductance resulted in greater internal diffusion limitations of photosynthesis in higher light. Both area- and mass-based g(m) decreased with increasing leaf age. The decrease in diffusion conductance was larger than changes in photosynthetic potentials, leading to larger CO2 drawdown from leaf internal air space to chloroplasts (delta(c)) in older leaves. The increases in diffusion limitations in older leaves and at higher light scaled with age- and light-dependent increases in MA and D(F). Overall, our study demonstrates a large potential of foliage photosynthetic acclimation to changes in leaf light environment, but also highlights enhanced structural diffusion limitations in older leaves that result from leaf structural acclimation to previous rather than to current light environment and accumulation of structural compounds with leaf age.

Acclimatization↗

PubMed1996

The plasma membrane protein SNAP-25, but not syntaxin, is present at photoreceptor and bipolar cell synapses in the rat retina.

The two neuronal plasma membrane proteins synaptosomal associated protein 25 kDa (SNAP-25) and syntaxin form, in current models of synaptic vesicle exocytosis, a docking complex on the presynaptic plasma membrane. This docking complex interacts with the integral synaptic vesicle protein, synaptobrevin. We have examined, in the rat retina, the distribution of SNAP-25 and syntaxin using light and electron microscopic immunocytochemistry. SNAP-25 immunoreactivity was present in the outer and inner nuclear layers at the membranes of photoreceptor and amacrine cell somata, in the outer plexiform layer in the terminals of photoreceptor cells and throughout the inner plexiform layer in the terminals of bipolar and amacrine cells. In contrast, syntaxin immunoreactivity was not found in the terminals of photoreceptor and bipolar cells, but only in the terminals of amacrine cells. Because of the absence of detectable syntaxin from the terminals of photoreceptor and bipolar cells, we propose that either a novel syntaxin isoform or a syntaxin-like protein exists at the ribbon synapses formed by these neurons.

Animals↗

PubMed2005

The role of prefrontal cortex in object-in-place learning in monkeys.

Previous ablation studies in monkeys suggest that prefrontal cortex is involved in a wide range of learning and memory tasks. However, monkeys with crossed unilateral lesions of frontal and temporal cortex are unimpaired at concurrent object-reward association learning but are impaired at conditional learning and the implementation of memory-based performance rules. We trained seven monkeys preoperatively on an associative learning task that required them to associate objects embedded in unique complex scenes with reward. Three monkeys then had crossed unilateral lesions of frontal and inferior temporal cortex and the remaining monkeys had bilateral prefrontal cortex ablation. Both groups were severely impaired postoperatively. These results show that both bilateral prefrontal cortex ablation and frontal-temporal disconnection impair associative learning for objects embedded in scenes. The results provide evidence that the function of frontal-temporal interactions in memory is not limited to conditional learning tasks and memory-dependent performance rules. We propose that rapid object-in-place learning requires the interaction of frontal cortex with inferotemporal cortex because visual object and contextual information which is captured over multiple saccades must be processed as a unique complex event that is extended in time. The present results suggest a role for frontal-temporal interaction in the integration of visual information over time.

Animals↗

PubMed1990

Comparison of the soluble and membrane-bound forms of the puromycin-sensitive enkephalin-degrading aminopeptidases from rat.

Enkephalin degradation in brain has been shown to be catalyzed, in part, by a membrane-bound puromycin-sensitive aminopeptidase. A cytosolic puromycin-sensitive aminopeptidase with similar properties also has been described. The relationship between the soluble and membrane forms of the rat brain enzyme is investigated here. Both of these aminopeptidase forms were purified from rat brain and an antiserum was generated to the soluble enzyme. Each of the aminopeptidases is composed of a single polypeptide of molecular mass 100 kilodaltons as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and size-exclusion chromatography. The antisoluble aminopeptidase antiserum reacts with both enzyme forms on immunoblots and inhibits both with nearly identical inhibition curves. The isoelectric points (pI = 5.0) of both forms were shown to be identical. N-terminal sequencing yielded a common sequence (P-E-K-R-P-F-E-R-L-P-T-E-V-S-P-I-N-Y) for both enzyme forms, and peptide mapping yielded 26 peptides that also appeared identical between the two enzyme forms. Studies on the nature of the association of the membrane enzyme form with the cell membrane suggest that this enzyme form does not represent the soluble form trapped during the enzyme preparation. It is suggested that the membrane form of the puromycin-sensitive aminopeptidase is identical to the soluble enzyme and that it associates with the membrane by interactions with other integral membrane proteins.

Amino Acid Sequence↗

PubMed1990

The relationships among the subsystems of Johnson's Behavioral System Model.

The major premise of the Johnson (1980) Behavioral System Model is that the eight subsystems (domains) are interactive, interdependent and integrated. Relationships among the subsystems were hypothesized, placing the Aggressive/Protective subsystem centrally as having direct and indirect relationships to the other seven subsystems. In the present study, the Behavioral System Model instrument generated two sets of scales that indicated changes as increase or decrease and positive or negative in the subsystem resulting from illness. Two causal models were tested, one for each set of scales, both supporting the hypotheses pertaining to the relationships between the Aggressive/Protective subsystem and the other subsystems. The findings warrant further investigation of these relationships and imply that changes in a domain resulting from illness cannot be well understood without understanding their relationship to changes in other domains.

Adolescent↗

PubMed1999

The rhythm of relating in a paradigm of wholeness.

The importance of relating to the rhythm of another person's interactive pattern is integral to helping people move through illness and disruptive events. At times of chaos, a person's rhythm may be irregular and difficult to sense, but transformation to higher levels of organization often occurs at far-from-equilibrium states. Nurses should develop a tolerance for ambiguity and uncertainty and "hang in there" with clients until a new rhythm emerges.

Empathy↗

PubMed2026

From isolation to insights: mitochondrial complex I in the diatom Phaeodactylum tricornutum.

Diatoms are among the most ecologically successful microalgae, contributing significantly to marine primary production and global carbon cycling. Their distinctive metabolic architecture, shaped by a complex evolutionary history involving secondary endosymbiosis, includes a highly compartmentalized cell organization and unique metabolic pathways. In Phaeodactylum tricornutum, a model pennate diatom, chloroplasts with four membranes and mitochondria of likely exosymbiotic origin exhibit intricate physical and metabolic interactions that support integrated carbon and nitrogen metabolism. The mitochondrial electron transport chain, essential for ATP synthesis, shows clade-specific structural and compositional adaptations. Despite its importance, detailed proteomic characterization has remained limited. Here, we report a method for the isolation of mitochondrial complex I from P. tricornutum and present a comprehensive proteomic analysis. Our results confirm the presence of carbonic anhydrase and bridge modules, both previously proposed as ancestral features of mitochondrial complex I, and identify at least one novel, clade-specific subunit that resembles NAD(P)H-dependent trans-2-enoyl-CoA/ACP reductases (TER) from other species. The subunit is similar to proteins involved in mitochondrial fatty acid biosynthesis. Our findings provide new insights into the composition, evolutionary conservation, and potential biotechnological relevance of this essential respiratory protein complex in diatoms.

Diatoms↗

PubMed2005

Ethylene signaling pathway.

The structural simplicity of the plant hormone ethylene contrasts with its dramatic effects in various developmental processes, as well as in the cellular processes that ethylene initiates in response to a diversity of environmental signals. A single well-conserved signaling cascade mediates this broad spectrum of responses. Ethylene is perceived by a family of two-component histidine kinase receptors that become inactivated upon ethylene binding. In the absence of the hormone, the receptors activate CTR1, a negative regulator of ethylene responses. Sequence similarity between CTR1 and the Raf protein kinases implies involvement of a mitogen-activated protein kinase cascade in this signaling pathway. The protein EIN2 acts downstream of CTR1 and the possible kinase cascade. Although the biochemical function of EIN2 is not understood, its critical role is manifested by the complete ethylene insensitivity of EIN2 loss-of-function mutants. Downstream of EIN2, a family of plant-specific EIN3-like transcription factors mediate ethylene responses. The regulation of EIN3 stability by ethylene is accomplished by F-box-containing proteins that participate in the formation of a SKP1/cullin/F-box complex that targets proteins for degradation by the proteasome. A large number of ethylene-regulated genes have been identified, including the APETALA2 domain-containing transcription factor genes ERF1 and EDF1 to 4, which suggests the participation of a transcriptional cascade in the ethylene response. The differential regulation of some components of this complex nuclear cascade by other signaling pathways provides a possible mechanism for interaction and signal integration. As new points of intersection with other pathways and additional participants in the pathway are identified, the Connections Map will be updated to include this new information.

Arabidopsis↗

PubMed1998

Determination of the chromosomal relationship between mecA and gyrA in methicillin-resistant coagulase-negative staphylococci.

mecA, the gene that mediates methicillin resistance, and its accompanying mec locus DNA, insert near the gyrA gene in Staphylococcus aureus. To investigate whether there is a similar relationship between mecA and gyrA in coagulase-negative staphylococci (CNS), mecA- and gyrA-specific DNA fragments were used to probe methicillin-resistant isolates of Staphylococcus epidermidis (MRSE) (n = 11) and Staphylococcus haemolyticus (MRSH) (n = 11). The gyrA probe hybridized to the same SmaI DNA fragment as the mecA probe in all strains tested. However, since the size of the SmaI fragments containing mecA and gyrA varied from 73 to 600 kb, the distance between the two genes was determined more precisely. Cloned mecA or gyrA fragments plus vector sequences each containing a SmaI site were introduced into the chromosome of three isolates each of MRSE and methicillin-resistant S. aureus (MRSA), and the sizes of the generated SmaI fragments were determined by pulsed-field gel electrophoresis. The distance between gyrA and mecA was found to be between 38 and 42 kb in both MRSE and MRSA, and the two genes were in the same relative orientation in all strains. Restriction fragment length polymorphism (RFLP) patterns around the gyrA gene in CNS were identical, but species specific, for all 10 MRSE and 10 MRSH isolates examined. In contrast, 8 of 11 methicillin-susceptible S. epidermidis isolates and 7 of 7 methicillin-susceptible S. haemolyticus isolates had different gyrA RFLP patterns. These data show that mecA is site and orientation specific, relative to gyrA, in both MRSE and MRSA. In addition, the local environment around gyrA in methicillin-resistant CNS, in contrast to methicillin-susceptible isolates, is similar, suggesting clonality or the requirement for specific DNA sequences with which the mec complex must interact for chromosomal integration to occur.

Bacterial Proteins↗