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PubMed1992

Dynamic decision making: human control of complex systems.

This paper reviews research on dynamic decision making, i.e., decision making under conditions which require a series of decisions, where the decisions are not independent, where the state of the world changes, both autonomously and as a consequence of the decision maker's actions, and where the decisions have to be made in real time. It is difficult to find useful normative theories for these kinds of decisions, and research thus has to focus on descriptive issues. A general approach, based on control theory, is proposed as a means to organize research in the area. An experimental paradigm for the study of dynamic decision making, that of computer simulated microworlds, is discussed, and two approaches using this paradigm are described: the individual differences approach, typical of German work in the tradition of research on complex problem solving, and the experimental approach. In studies following the former approach, the behaviour of groups differing in performance is compared, either with respect to strategies or with respect to performance on psychological tests. The results show that there are wide interindividual differences in performance, but no stable correlations between performance in microworlds and scores on traditional psychological tests have been found. Experimental research studying the effects of system characteristics, such as complexity and feedback delays, on dynamic decision making has shown that decision performance in dynamic tasks is strongly affected by feedback delays and whether or not the decisions have side effects. Although neither approach has led to any well-developed theory of dynamic decision making so far, the results nevertheless indicate that we are now able to produce highly reliable experimental results in the laboratory, results that agree with those found in field studies of dynamic decision making. This shows that an important first step towards a better understanding of these phenomena has been taken.

Computer Simulation↗

PubMed1992

Doppler assessment of right ventricular filling dynamics in systemic hypertension: comparison with left ventricular filling.

To assess right ventricular filling dynamics in systemic hypertension, pulsed Doppler echocardiographic studies were obtained at the tricuspid and mitral anuli in 43 untreated hypertensive patients, aged 23 to 66 years, and in 42 age-matched normotensive control subjects. In hypertensive patients, the ratio of late to early peak filling velocity and atrial filling fraction were higher, while normalized peak filling rate, one third and one half filling fractions were lower, compared with control values. Right ventricular filling dynamics correlated poorly with age in hypertensive patients, and were unrelated to left ventricular mass or left ventricular wall thickness. Weak correlations were only found between right ventricular wall thickness and right ventricular peak late inflow velocity, first half and first third filling fractions. However, right ventricular filling dynamics were closely related to left ventricular filling dynamics in both hypertensive patients (r = 0.49 to 0.82) and normal individuals (r = 0.55 to 0.86). Thus right ventricular filling dynamics are altered in hypertension, independently of left ventricular mass or blood pressure, are weakly related to right ventricular thickness, but remain closely correlated to left ventricular filling dynamics.

Adult↗

PubMed1993

Dynamic cardiomyoplasty in chronic left ventricular failure: an experimental model.

Dynamic cardiomyoplasty continues to attract interest as a therapeutic option in the management of heart failure. In a large animal model of ischemic heart failure, we have compared dynamic cardiomyoplasty with both adynamic cardiomyoplasty and a control group. Heart failure was induced by coronary artery ligation in sheep, and under the same anesthetic dynamic cardiomyoplasty (n = 5), adynamic cardiomyoplasty (n = 4), or no further procedure was performed (n = 5). After recovery the animals were housed for a further 3 months. The dynamic cardiomyoplasty underwent a recognized muscle transformation protocol during this period. At terminal studies, the animals were hemodynamically assessed, both under baseline conditions and after colloid volume loading. The data at baseline were compared with unpaired t tests, and the function curves created by volume loading were compared by analysis of variance. Although the changes at baseline were small, there were highly significant improvements in the function curves in the dynamic cardiomyoplasty group when the stimulators were turned on compared with stimulators off (p = 0.005) for cardiac output; p = 0.035 for left ventricular end-diastolic pressure; p = 0.002 for pulmonary artery capillary wedge pressure; p = 0.004 for stroke volume; and p = 0.003 for cardiac power). There were also significant improvements in indices of cardiac performance when the dynamic cardiomyoplasty group was compared with both the control and adynamic cardiomyoplasty groups. We conclude that there is experimental evidence that cardiomyoplasty augments cardiac function in a model of chronic left ventricular failure.

Animals↗

PubMed1991

Proton nuclear magnetic resonance studies on the molecular dynamics of plasmenylcholine/cholesterol and phosphatidylcholine/cholesterol bilayers.

Physiologically relevant molecular species of plasmenylcholine and phosphatidylcholine were synthesized and their molecular dynamics and interactions with cholesterol were compared by determination of salient proton spin-lattice relaxation times and apparent activation energies for 1H-NMR observable motion. The molecular dynamics of PA PhosCho (1-hexadecanoyl-2-eicosatetra-5',8',11',14'-enoyl-sn-glycero-3-pho sphocholine) in multiple regions of the bilayer. Furthermore, the fluidity gradient of PA PhosCho was larger than that of PA PlasCho as ascertained by 1H spin-lattice relaxation time measurements. Introduction of cholesterol into each bilayer resulted in disparate effects on the dynamics of each subclass including: (1) increased motional freedom in the polar head group of PA PlasCho without substantial alterations in the dynamics of the polar head group of PA PhosCho; and (2) increased immobilization of the membrane interior in PA PlasCho in comparison to PA PhosCho. Analysis of Arrhenius plots of T1 relaxation times demonstrated that the apparent activation energies for vinyl and bisallylic methylene proton NMR observable motion in PA PhosCho were greater than that in PA PlasCho. Thus, comparisons of spin-lattice relaxation times and apparent activation energies demonstrate that vesicles comprised of PA PlasCho and PA PhosCho possess differential molecular dynamics and distinct interactions with cholesterol. Collectively, these results underscore the significance of the conjoint presence of the vinyl ether linkage and arachidonic acid as an important determinant of membrane dynamics in specialized mammalian membranes.

Cholesterol↗

PubMedDate not supplied

Dynamic unconfined compression of articular cartilage under a cyclic compressive load.

To study the effect of dynamic mechanical force on cartilage metabolism, many investigators have applied a cyclic compressive load to cartilage disc explants in vitro. The most frequently used in vitro testing protocol has been the cyclic unconfined compression of articular cartilage in a bath of culture medium. Cyclic compression has been achieved by applying either a prescribed cyclic displacement or a prescribed cyclic force on a loading platen placed on the top surface of a cylindrical cartilage disc. It was found that the separation of the loading platen from the tissue surface was likely when a prescribed cyclic displacement was applied at a high frequency. The purpose of the present study was to simulate mathematically the dynamic behavior of a cylindrical cartilage disc subjected to cyclic unconfined compression under a dynamic force boundary condition protocol, and to provide a parametric analysis of mechanical deformations within the extracellular matrix. The frequency-dependent dynamic characteristics of dilatation, hydrostatic pressure and interstitial fluid velocity were analyzed over a wide range of loading frequencies without the separation of the loading platen. The result predicted that a cyclic compressive force created an oscillating positive-negative hydrostatic pressure together with a forced circulation of interstitial fluid within the tissue matrix. It was also found that the load partitioning mechanism between the solid and fluid phases was a function of loading frequency. At a relatively high loading frequency, a localized dynamic zone was developed near the peripheral free surface of the cartilage disc, where a large dynamic pressure gradient exists, causing vigorous interstitial fluid flow.

Biomechanical Phenomena↗

PubMed1992

The dynamic ASIF-BM tubular external fixator in the treatment of open fractures of the shaft of the tibia.

The dynamic ASIF-BM external fixator incorporates telescopic tubes for axial dynamization and angled bayonet screws to keep the tubes parallel to the bone axis, that is essential for gliding, and adjustment of rotation. The results after treatment of 70 type II and III open tibial fractures with static ASIF and dynamic ASIF-BM frames were analysed. Of the fractures, 32 were treated with the delta ASIF static frame, the other 38 with delta and uniplanar dynamic ASIF-BM frames. The groups were found to be comparable. The results of the study confirm that tubular external fixation is a safe method for treating the bone and soft tissue lesions in such fractures. The comparative study shows that axial compression, using the ASIF-BM device, with early weight bearing, gave a higher rate of union (97 per cent against 87 per cent with the ASIF frame), a shorter healing time (19 weeks against 29 weeks with the ASIF frame) and a decreased need for bone grafting (21 per cent against 84 per cent with the ASIF frame). The incidence of pin track infection was also decreased in dynamic frames. Thus it seems that the ASIF-BM dynamic fixator has a valuable part to play as a definitive mode of therapy for severe open fractures of the tibial shaft.

Adolescent↗

PubMed1985

Dynamically and statically determined low back moments during lifting.

Assessment of the effects of lifting on the low back has most frequently been done with the aid of static models. Many lifting movements appear to have substantial inertial components. It was of interest, therefore, to determine the size of the difference between statically and dynamically calculated lumbar moments during a demanding but not unusual manual lift observed in a metal fabrication industry. The results of several trials by four young men showed that the dynamic model resulted in peak L4/L5 moments 19% higher on average, with a maximum difference of 52%, than those determined from the static model. The technique adopted in the lift could minimize the difference. When the inertial forces of the load itself and the load weight were incorporated into an otherwise static model (quasi-dynamic) then the resulting L4/L5 moments exceeded those of the fully dynamic model by 25%. In many industrial tasks static analyses may severely underestimate the demands of dynamic lifts. These results show that a reasonably inexpensive approach in lifting task analysis is to measure the dynamic forces of the load on the hands and to use these in an otherwise static model. This results in a conservative assessment of the injury risk of lifts at least of the type reported in this study.

Adult↗

PubMed1995

Dynamic behavior of a biphasic cartilage model under cyclic compressive loading.

It is well known that dynamic mechanical loads can stimulate the biosynthetic activity of articular cartilage. Studying the mechanical environment of chondrocytes under dynamic loading conditions can help to explain this mechano-biological phenomenon in articular cartilage. In this study, the linear biphasic theory was used to examine the dynamic mechanical behavior of articular cartilage under a cyclic compressive force. We first studied the dynamic confined compression of a cartilage disk as a simplified one-dimensional model and then investigated the role of the relatively impermeable subchondral bone structure on the dynamic behavior of the cartilage extracellular matrix (ECM). Under an assumption of articular cartilage as a biphasic composite structure of a porous elastic solid matrix and interstitial fluid, the porous ECM of the articular cartilage was repeatedly compressed and expanded during the loading-unloading phases of the cyclic compressive force. One interesting finding of this study was the oscillating positive (supra-ambient)-negative (sub-ambient) hydrostatic pressure within the cartilage ECM under cyclic compressive loading. The pattern of the dynamic behavior of the cartilage ECM strongly depended on the loading frequency and the primary diffusion characteristic time, tau d. This finding is consistent with those of previous studies (Guilak et al., 1990 Adv Biomech. ASME, 225-228; Mow et al., 1990, Biomechanics of Diarthrodial Joints, pp. 215-260.

Algorithms↗

PubMed1995

An EMG-assisted model of trunk loading during free-dynamic lifting.

One of the continuing challenges in biomechanics has been to assess loading of the spine during dynamic lifting exertions. A model was developed to accurately simulate multi-dimensional spinal loads and trunk moments from measured muscle coactivity and external forces during free-dynamic lifting exertions. Model validity was demonstrated by comparing measured and predicted trunk extension moments. Its purpose was to examine realistic representations of lifting kinetics, kinematics, and dynamic trunk mechanics that may influence spinal loading, and to demonstrate that EMG-assisted modeling techniques can be applied to the analysis of free-dynamic exertions. Spinal loads and trunk moments were predicted from the muscle force vectors and external loads. Muscle tensile forces were determined from the product of normalized EMG data modulated to account for contractile dynamics, muscle cross sectional area, and muscle force per unit cross-sectional area. Model output was physiologically valid, i.e. average predicted muscle force per unit cross-sectional area of 50-65 N cm-2, and accurately predicted measured, dynamic, lifting moments, with an average R2 = 0.81 in the sagittal plane and R2 = 0.76 in the lateral plane. Results indicated that compressive and shear loading increased significantly with exertion load, lifting velocity, and trunk asymmetry.

Abdominal Muscles↗

PubMed1989

Dynamical structure of carboxypeptidase A.

Structural fluctuations of the apoenzyme form of carboxypeptidase A (EC 3.4.12.2) have been evaluated on the basis of molecular dynamics. The Konnert-Hendrickson refined coordinates of 2437 non-hydrogen atoms of the 307 amino acid residues derived from the X-ray structure of the holoenzyme served as the molecular model together with 548 calculated polar hydrogen atoms and 25 buried solvent molecules. Molecular dynamics simulations were carried out at 277 K, and the averaged structural properties of the protein were evaluated for the terminal 20 picosecond portion of a 48 picosecond trajectory. The average atomic displacement from the initial X-ray structure was 2.49 A for all atoms and 1.79 A for C alpha atoms. The average root-mean-square (r.m.s.) fluctuation of all atoms was 0.67 A as compared to 0.54 A evaluated from the X-ray-defined temperature factors. Corresponding r.m.s. fluctuations for backbone atoms were 0.56 A by molecular dynamics and 0.49 A by X-ray. On the basis of these molecular dynamics studies of the isolated molecule, it is shown that amino acid residues corresponding to intermolecular contact sites of the crystalline enzyme are associated with high amplitude motion. All eight segments of alpha-helix and eight regions of beta-strand were well preserved except for unwinding of the five C-terminal residues of the alpha-helix 112-122 that form part of an intermolecular contact in the crystal. Four regions of beta-strand and one alpha-helix with residues adjacent to or in the active site constitute a core of constant secondary structure and are shown not to change in relative orientation to each other during the course of the trajectory. The absence of the zinc ion does not markedly influence the stereochemical relationships of active site residues in the dynamically averaged protein. The extent of motional fluctuations of each of the subsites of substrate recognition in the active site has been evaluated. Active site residues responsible for specificity of substrate binding or splitting of the scissile bond exhibit low simulated motion. In contrast, residues in more distal sites of substrate recognition exhibit markedly greater motional fluctuations. This differential extent of dynamical motion is related to structural requirements of substrate hydrolysis.

Amino Acid Sequence↗

PubMed1992

Solution structure of a DNA octamer containing the Pribnow box via restrained molecular dynamics simulation with distance and torsion angle constraints derived from two-dimensional nuclear magnetic resonance spectral fitting.

The DNA octamer [d(GTATAATG].[(CATATTAC)], containing the prokaryotic upstream consensus recognition sequence, has been examined via proton homonuclear two-dimensional nuclear Overhauser effect (2D NOE) and double-quantum-filtered correlation (2QF-COSY) spectra. All proton resonances, except those of H5' and H5" protons, were assigned. A temperature dependence study of one-dimensional nuclear magnetic resonance (NMR) spectra, rotating frame 2D NOE spectroscopy (ROESY), and T1 rho measurements revealed an exchange process that apparently is global in scope. Work at lower temperatures enabled a determination of structural constraints that could be employed in determination of a time-averaged structure. Simulations of the 2QF-COSY cross-peaks were compared with experimental data, establishing scalar coupling constant ranges of the individual sugar ring protons and hence pucker parameters for individual deoxyribose rings. The rings exhibit a dynamic equilibrium of N and S-type conformers with 80 to 100% populations of the latter. A program for iterative complete relaxation matrix analysis of 2D NOE spectral intensities, MARDIGRAS, was employed to give interproton distances for each mixing time. According to the accuracy of the distance determination, upper and lower distance bounds were chosen. The distance bounds define the size of a flat-well potential function term, incorporated into the AMBER force-field, which was employed for restrained molecular dynamics calculations. Torsion angle constraints in the form of a flat-well potential were also constructed from the analysis of the sugar pucker data. Several restrained molecular dynamics runs of 25 picoseconds were performed, utilizing 184 experimental distance constraints and 80 torsion angle constraints; three different starting structures were used: energy minimized A-DNA, B-DNA, and wrinkled D-DNA, another member of the B-DNA family. Convergence to similar structures obtained with root-mean-square deviations between resulting structures of 0.37 to 0.92 A for the central hexamer of the octamer. The average structure from the nine different molecular dynamics runs was subjected to final restrained energy minimization. The resulting final structure was in good agreement with the structures derived from different molecular dynamics runs and exhibited a substantial improvement in the 2D NOE sixth-root residual index in comparison with the starting structures. An approximation of the structure in the terminal base-pairs, which displayed experimental evidence of fraying, was made by maintaining the structure of the inner four base-pairs and performing molecular dynamics simulations with the experimental structural constraints observed for the termini.(ABSTRACT TRUNCATED AT 400 WORDS)

Base Sequence↗

PubMed1983

Co-operative dynamics in organelles.

Some organelles produce elementary life phenomena which are characterized by the spontaneous formation and/or maintenance of ordered macroscopic dynamics like e.g. the shortening of sarcomeres in striated muscle and the transmission of electrical impulses in an axon. It has been widely accepted that such organelles are organized molecular systems where molecular elements work independently under constraint of a more or less rigid and regular structure of the system. On the other hand, such organelles should be regarded as self-organizing systems if the ordered macroscopic dynamics are self-organized. As the macroscopic dynamics gradually emerge, the microscopic dynamics of its elements become linked to each other through a feedback loop. It is crucial for the feedback loop to operate that the macroscopic dynamics are "free" in their behavior. In the present paper, it is pointed out that the traditional view of independent molecular elements has been obtained from experiments in which, by means of external constraint, the macroscopic dynamics is "clamped". Under such conditions, the self-organizing system may behave as an organized one. Based on synergetics we propose criterions for proving self-organizing systems, and, by applying the criterions, we conclude that skeletal muscle actomysin is a co-operative element in the sense of self-organization.

Actins↗

PubMed1993

Dynamics of the ventilatory response to hypoxia in humans.

Dynamic responses of the ventilatory system to rapid variations in isocapnic hypoxia were studied in five subjects. Sawtooth-shaped inputs were presented at constant amplitude with periods of 120, 90, 60, 45 and 30 sec, and square-wave inputs at different amplitudes with periods of 120, 60 and 30 sec. A breath-by-breath model fitting technique was used to assess whether any of a number of first order models of hypoxic ventilatory dynamics could fit the data adequately. The following was found: 1) An equation for the desaturation of haemoglobin provided a better expression for hypoxia in the model than did a hyperbolic function of PO2. 2) The gain and/or offset model parameters varied significantly between experiments, but the time constant and pure delay terms did not. 3) The time constants, and to a lesser extent the pure delays, were found to vary significantly between sawtooth experiments of different frequencies. The failure of a single set of dynamic parameters to describe all the responses suggests that the model is incomplete. 4) There was significant asymmetry in the hypoxic response with the on-transient dynamics faster than the off-transient dynamics. The results of the model fitting study suggest that a first order model cannot fully describe the hypoxic ventilatory dynamics.

Carbon Dioxide↗

PubMed1988

Dynamic stereotactic radiosurgery.

Two radiosurgical procedures using a stereotactic frame and a linear accelerator X ray beam with a circular field diameter between 0.5 and 3 cm are presented. One technique is based on a single plane rotation (single plane radiosurgery) whereas the other uses simultaneous and continuous motions of both the gantry (approximately 360 degrees) and couch (approximately 180 degrees) during the radiosurgical procedure (dynamic radiosurgery). The dose, typically a few thousand cGy, is prescribed to the 90% isodose line which just covers the target volume. The dose fall-off outside the spherical target volume is considerably sharper for the dynamic rotation than for the single plane rotation, and is comparable to the dose fall-off obtained with the two presently known dedicated radiosurgical techniques: one based on focused cobalt beams and the other on proton beams. The dose fall-off in the dynamic radiosurgery discussed here is also comparable to that of previously described linear accelerator based multiple converging are techniques, making the dynamic radiosurgery an attractive alternative to presently known radiosurgical procedures. The radiation beam parameters are discussed and the stereotactic frame described. The dose distributions for both radiosurgical techniques are calculated in a single plane and then corrected for the attenuation effects in the stereotactic frame (approximately 2%) and for the effects of the dynamic rotation (approximately 2%). The skin doses are 0.7% and 2%, and the lens doses, if the beam passes through the eyes, are 2.5% and 3.5% for the dynamic rotation and single plane rotation, respectively. The scatter and leakage dose for the radiosurgical procedures is typically 0.2% to the patient's thyroid, 0.06% to the breast, and 0.02% to the gonads.

Brain Diseases↗

PubMed1995

Tissue compensation using dynamic collimation on a linear accelerator.

PURPOSE: The availability of computer-controlled collimators on some accelerators has led to techniques for dynamic beam modification, mainly to simulate beam wedge filters. This work addresses the practical aspects of dynamic tissue compensation in one dimension using available treatment-planning software. METHODS AND MATERIALS: Data derived from the treatment-planning program is used with an iterative calculational routine to determine the monitor unit settings needed for the collimator-controlling computer. The method was first tested by simulating a 60 degrees physical wedge. Further studies were carried out on a specially fabricated plastic phantom that modeled the sagittal contour of the upper torso, neck, and lower head regions. RESULTS: Dynamic wedge point doses generated by the planning program agreed within 1% with the values directly measured in a polystyrene phantom. In the patient phantom, dynamic collimation achieved calculated dose uniformity within 0.5% in a reference plane near the phantom midline. A comparison of computer-generated and measured point doses in this case showed agreement within 3%. CONCLUSIONS: Dynamic collimation can provide effective compensation for contours that vary primarily along one direction. A conventional treatment-planning program can be used to plan dynamic collimation and deliver a prescribed dose with reliable accuracy.

Models, Anatomic↗

PubMed2005

Role of nutrient bound of prey on the dynamics of predator-mediated competitive-coexistence.

The coexistence of competitive species with a shared predator is well established. The effect of 'food-value' on predator-prey dynamics has also received much attention. However, the study of a nutrient bound of prey, specifically on predator-mediated competitive-coexistence has not received much attention. Here we study the effects of the caloric content or a nutrient bound of prey on the dynamics of competitive-coexistence with the shared predator in a specific model. We propose and analyze a mathematical model for exploitative competition of two prey species with a shared predator. The change of dynamic stability due to the variation of a nutrient bound of each prey on predator-mediated dynamics is studied through extensive numerical experiments. Our analytical and numerical results demonstrate that variation in a nutrient bound promotes the switching of dynamics and may be treated as a driving force for the dynamics of competitive-coexistence with the shared predator.

Animal Nutritional Physiological Phenomena↗

PubMed2005

Computational simulation of axial dynamization on long bone fractures.

BACKGROUND: Axial dynamization has been shown in previous studies to promote callus formation, improve bone healing at fracture sites, and enhance bone remodeling. However, the possibility of non-axial movements or uniform fracture site compression during dynamization, and the appropriate relaxation of fixator joints to achieve such function, have not been investigated. METHODS: This study used previously developed computational models based on two commercially available unilateral external fixators (Dynafix and Orthofix) to analyze the fixator joint adjustments used and the fracture site movements generated during dynamization. FINDINGS: When none of the fixator's sliding joints were parallel to the long bone axis, significant non-axial movements occurred during dynamization. The dual sliding joint design of the Dynafix fixator was beneficial in reducing these non-axial movements. When all of the fixator joints were allowed to adjust simultaneously during dynamization, exact axial movement or uniform compression at a complicated fracture site was achievable. INTERPRETATION: This study revealed that significant non-axial movements may occur during dynamization, and that such a deficiency can be corrected by relaxing certain fixator joints in addition to the sliding mechanism. The same modeling technique can also be applied in bone lengthening application to assure desirable limb alignment during the distraction process. These analysis results can aid the performance assessment of an external fixator and facilitate appropriate application of such a device to achieve either active or controlled axial movement.

Computer Simulation↗

PubMed2006

Sagittal plane motion in the human lumbar spine: comparison of the in vitro quasistatic neutral zone and dynamic motion parameters.

BACKGROUND: Disabling low back pain is often attributed to clinical instability but defining instability is problematic. The most common parameter used to characterize instability in the lab is the neutral zone which is measured with a quasi-static technique. But, it cannot be measured from continuous motion data. Our goal was to describe the relationship between the quasi-static neutral zone and dynamic motion parameters that might reflect laxity about the neutral position. We also sought to determine if dynamic parameters were correlated with disc degeneration. METHODS: Fifteen cadaveric lumbar motion segments were tested with both quasi-static and dynamic (continuous load) methods. Quasi-static range of motion and neutral zone were compared with dynamic range of motion, hysteresis loop width, and two parameters derived from the hysteresis data: transitional zone size and slope. Degeneration was graded macroscopically. FINDINGS: Neutral zone size was moderately correlated with hysteresis loop width (r=0.69) and strongly correlated with the transitional zone slope (r=-0.80). Degenerative grade had a significant effect on dynamic range of motion and transitional zone size and slope with differences found between grade 1 (normal) discs and higher grades. Only transitional zone slope was different between grades 1 and 2. INTERPRETATION: The transitional zone slope (representing the neutral region stiffness) had the strongest correlation with neutral zone and could best detect lower grades of degeneration. The transitional zone slope might be a useful parameter in dynamic studies investigating the association between degeneration and motion segment behavior.

Adult↗