Single Excursion Research Articles

High-altitude decompression strain can be reduced by an early excursion to moderate altitude while breathing oxygen

Recent observations suggest that development of venous gas emboli (VGE) during high-altitude flying whilst breathing hyperoxic gas will be reduced by intermittent excursions to moderate altitude. The present study aimed to investigate if an early, single excursion from high to moderate altitude can be used as an in-flight means to reduce high-altitude decompression strain. Ten healthy men were investigated whilst breathing oxygen in a hypobaric chamber under two conditions, once during a 90-min continuous exposure to a simulated cabin altitude of 24,000 ft (High; H) and once during 10 min at 24,000 ft, followed by 30 min at 15,000 ft and by 80 min at 24,000 ft (high–low–high; H–L–H). VGE scores were assessed by cardiac ultrasound, using a 6-graded scale. In H, VGE increased throughout the course of the sojourn at 24,000 ft to attain peak value [median (range)] of 3 (2–4) at min 90, just prior to descent. In H–L–H, median VGE scores were 0 throughout the trial, except for at min 10, just prior to the excursion to 15,000 ft, whence the VGE score was 1.5 (0–3). Thus, an early, single excursion from high to moderate cabin altitude holds promise as an in-flight means to reduce the risk of altitude decompression sickness during long-duration high-altitude flying in aircraft with limited cabin pressurization. Presumably, such excursion acts by facilitating the gas exchange in decompression bubbles from a predomination of nitrogen to that of oxygen.

Grid mapping revealed hidden geochemical lens and its chemostratigraphic bias in the middle‐upper Permian marine carbonate sequence in Laibin, South China

Deep‐time chemostratigraphy provides important data for stratigraphy and palaeoenvironmental reconstruction. Geochemical analysis for the same proxy from the same outcrop section, however, often results in different data among various researchers. The dispute was ascribed to inappropriate screening of samples weathering, pre‐treatment, and analytical methods. An outstanding example is that a great variation of 1–3‰ in δ13CVPDB values from the same horizons at Auxiliary Global Stratotype of Section and Point for the Guadalupian–Lopingian (G‐L) boundary in Tieqiao, Laibin, South China was obtained by various research groups. The Walther's Law of Facies suggests that such differences in analytical results may be due to the diachronism of samples measured in high‐resolution stratigraphy. Although lithology and broad sedimentary facies are the same in a lithostratigraphic unit, heterogeneous distribution of bioclastics, δ13Corg, provenances, trace elements, and age‐controlling geochemical signals might have printed on sediments within the same bed. Here, we verified the variations by grid mapping and sampling, a new method for high‐resolution chemostratigraphy, and this practice is applied to the auxiliary GSSP at the Tieqiao section. A total of nine parallel columnar sections from the upper Guadalupian to lowest Lopingian were measured and sampled. In addition, four lateral profiles along four beds were also sampled, and two of them are close to the lower part of the section (upper Guadalupian) and near the G‐L boundary, respectively. These analytical results are plotted along the coordinate of X–Y axis and form the grid mapping on the outcrop. Contour maps of various proxies (i.e., CaO%, total Fe%, and δ13Ccarb) based on the grid mapping were constructed on the outcrop, instead of single excursions of various geochemical proxies throughout the upper Guadalupian to lowest Lopingian. The results show different negative excursions of δ13Ccarb coinciding with biotic extinction near the G‐L boundary and answered the differences of proxy reported in previous studies. Grid mapping of various proxies shows general trends of the proxies on the outcrop; however, there are invisible beddings across lenses in dozens meters size of geochemical abnormal. Analytical data of the same proxy from the same horizons at different columnar sections may present different excursions if sampling on the abnormal lenses or not. This is why the data are different among various studies when different columnar sections were sampled. Various lenses of geochemical abnormal which may be linked tectonic controlled diagenesis, and microhabitat et al., and resulted in the bias from different columnar sections were sampled.

Contact Resistance Behavior of Land Grid Array Sockets at Cryogenic Temperatures Required for Quantum Measurements

The current state of quantum device maturity proposes the use of removable, reusable interconnection means between such device and their classical microelectronic measurement system. One such means is a land grid array (LGA) socket, used pervasively in microelectronics but relatively untested at cryogenic temperatures necessary for most quantum technologies. This article investigates two distinct commercially available LGA socket technologies with respect to contact resistance performance under cryogenic temperature measurement conditions. Test methodologies were successfully developed for both sockets, demonstrating predictable and repeatable contact resistance values during multiple excursions down to 1.5 K and a single excursion to 10 mK. The experimental data show that contact resistance of individual interconnection sites decreased from 30 to 40 $\text{m}\Omega $ at room temperature to 14-17 $\text{m}\Omega $ at 1.5 K and to 6–8 $\text{m}\Omega $ at 10 mK, thus supporting their reliable use in cryogenic measurement applications. Theoretical calculations based on the construction of the microspring socket validated that measured values behaved in a manner that was consistent with temperature-dependent changes in resistivity of the metals comprising the socket interconnection. Spring deflection allowances compensated for any temperature-driven movement of components within the assembly, thus enabling predictable resistance behavior. Regarding the elastomer socket, the high coefficient of thermal expansion (CTE) of the elastomer bulk material induced large variations in socket compression across the temperature range investigated. Sufficient compression to provide consistent contact resistance values at cryogenic temperatures imposed the need for very high compression at room temperature, which may place into question the longer term integrity of this solution. Nevertheless, a preliminary investigation (five cryogenic cycles and subsequent construction analysis) did not reveal any degradation in either socket type.

Robust Characteristics of the Laschamp and Mono Lake Geomagnetic Excursions: Results From Global Field Models

Data-based global palaeomagnetic field models provide a more complete view of geomagnetic excursions than individual records. They allow the temporal and spatial field evolution to be mapped globally, and facilitate investigation of dipole and non-dipole field components. We have developed a suite of spherical harmonic (SH) field models that span 50 to 30 ka and include the Laschamp (~41 ka) and Mono Lake (~33 ka) excursions. Palaeomagnetic field models depend heavily on the data used in their construction. Variations in palaeomagnetic sediment records from the same region are in some cases inconsistent. To test the influence of data selection and reliance on age models, we have built a series of SH models based upon different data sets. A number of excursion characteristics are robust in all models, despite some differences in energy distribution among SH coefficients. Quantities such as field morphology at the core-mantle boundary (CMB) or individual SH degree power variations should be interpreted with caution. All models suggest that the excursion process during the Laschamp is mainly governed by axial dipole decay and recovery, without a significant influence from the equatorial dipole or non-dipole fields. The axial dipole component reduces to almost zero, but does not reverse. This results in excursional field behaviour seen globally, but non-uniformly at Earth's surface. The Mono Lake excursion may be a series of excursions occurring between 36 and 30 ka rather than a single excursion. In contrast to the Laschamp, these excursions appear driven by smaller decreases in axial dipole field strength during a time when the axial dipole power at the CMB is similar to the power in the non-dipole field. We suggest three phases for the 50 to 30 ka period: (1) a broadly stable phase dominated by the axial dipole (50-43 ka); (2) the Laschamp excursion, with the underlying excursion process lasting ~5 ka (43-38 ka) and the surface field expression lasting ~2 ka (42-40 ka); (3) a weak phase during which axial dipole and non-dipole power at the CMB are comparable, leading to more than one excursion between 36 and 30 ka.

A re-evaluation of the hull girder shakedown limit states

ABSTRACTThis paper investigates the use of shakedown limit state in the assessment of longitudinal strength of ship hull girders. This consideration is related to the fact that a structural system subjected to cyclic loadings may suffer from plastic collapse even when the loading magnitude is less than the instantaneous collapse load of single excursion. This paper first evaluates the shakedown limit state of a box girder model with and without the consideration of buckling. Nonlinear finite element analyses are also performed to investigate the structural behaviours of a case study model under six different cyclic loading protocols. The rationality of a shakedown limit state is discussed and an energy-based characterisation of limit state is suggested. The study shows that, whilst the use of shakedown limit state assessment may be overly conservative, the safety margin based on an ultimate limit state approach might be considerably reduced.

Glycemic Management as the Primary Determinant of One-Year Mortality after CABG

Factors linked to mortality after coronary artery bypass graft (CABG) include post-operative hypoglycemia and graft source. However, it is unknown if there is an interaction between these two factors, namely whether arterial grafts withstand hypoglycemia better than veins after CABG. In a cohort of 1323 patients undergoing CABG with intensive insulin therapy (IIT) in the ICU, we identified graft sources, ICU glucometrics, diabetes (DM) status and one-year mortality. Glucometrics included mean BG in ICU, and hypoglycemic excursions (Incidence, Severity [nadir <40, 40-69mg/dl], Repetitive Frequency [number of excursions/patient]). The impact of different factors, individually and in combination, was analyzed by Chi-squared Automatic Interaction Detection (CHAID). One year mortality was highest in those with BG<40mg/dl in the ICU (12/26, 46%) vs. those without (67/1283, 5%, p<0.001). No other factor was significant in those with BG<40. Of those without BG<40, repetitive (≥2) excursions with BG<70mg/dL had the highest mortality (17/96, 17%, p<0.001), vs. those with one (13/190, 7%) or no excursions (37/997, 4%). Graft source was dominated by other factors in one year mortality, except for the left internal thoracic artery which was protective only in patients who had no hypoglycemia. Hyperglycemia was a contributor to mortality in patients who had a single hypoglycemic excursion <70 (ICU Mean BG>152mg/dl 4/17, 24% vs. ≤152 9/173, 5%, p=0.039) Preexisting DM was protective in patients with repetitive hypoglycemia (DM 2/43, 5% vs. 15/53 28%, p=0.003). Hypoglycemia in the ICU has a durable impact on one-year mortality post-CABG, superseding graft source, which is only significant without hypoglycemia. Severe hypoglycemia poses the greatest risk, but even mild repetitive BG<70 is a threat to one year survival. In conclusion, hypoglycemia erases the survival benefit from arterial grafts, suggesting that it may be equally damaging, regardless of graft source, and far more durable than hitherto envisioned. Disclosure L. Heller: None. M. Zupa: None. P.L. Perreiah: None. R. Rao: None.

Characterization of K-complexes and slow wave activity in a neural mass model.

NREM sleep is characterized by two hallmarks, namely K-complexes (KCs) during sleep stage N2 and cortical slow oscillations (SOs) during sleep stage N3. While the underlying dynamics on the neuronal level is well known and can be easily measured, the resulting behavior on the macroscopic population level remains unclear. On the basis of an extended neural mass model of the cortex, we suggest a new interpretation of the mechanisms responsible for the generation of KCs and SOs. As the cortex transitions from wake to deep sleep, in our model it approaches an oscillatory regime via a Hopf bifurcation. Importantly, there is a canard phenomenon arising from a homoclinic bifurcation, whose orbit determines the shape of large amplitude SOs. A KC corresponds to a single excursion along the homoclinic orbit, while SOs are noise-driven oscillations around a stable focus. The model generates both time series and spectra that strikingly resemble real electroencephalogram data and points out possible differences between the different stages of natural sleep.

Emergent exploration via novelty management.

When encountering novel environments, animals perform complex yet structured exploratory behaviors. Despite their typical structuring, the principles underlying exploratory patterns are still not sufficiently understood. Here we analyzed exploratory behavioral data from two modalities: whisking and locomotion in rats and mice. We found that these rodents maximized novelty signal-to-noise ratio during each exploration episode, where novelty is defined as the accumulated information gain. We further found that these rodents maximized novelty during outbound exploration, used novelty-triggered withdrawal-like retreat behavior, and explored the environment in a novelty-descending sequence. We applied a hierarchical curiosity model, which incorporates these principles, to both modalities. We show that the model captures the major components of exploratory behavior in multiple timescales: single excursions, exploratory episodes, and developmental timeline. The model predicted that novelty is managed across exploratory modalities. Using a novel experimental setup in which mice encountered a novel object for the first time in their life, we tested and validated this prediction. Further predictions, related to the development of brain circuitry, are described. This study demonstrates that rodents select exploratory actions according to a novelty management framework and suggests a plausible mechanism by which mammalian exploration primitives can be learned during development and integrated in adult exploration of complex environments.

The Blake geomagnetic excursion recorded in a radiometrically dated speleothem

One of the most important developments in geomagnetism has been the recognition of polarity excursions of the Earth's magnetic field. Accurate timing of the excursions is a key point for understanding the geodynamo process and for magnetostratigraphic correlation. One of the best-known excursions is the Blake geomagnetic episode, which occurred during marine isotope stage MIS 5, but its morphology and age remain controversial. Here we show, for the first time, the Blake excursion recorded in a stalagmite which was dated using the uranium-series disequilibrium techniques. The characteristic remanent magnetisation is carried by fine-grained magnetite. The event is documented by two reversed intervals (B1 and B2). The age of the event is estimated to be between 116.5±0.7kyr BP and 112.0±1.9kyr BP, slightly younger (∼3–4kyr) than recent estimations from sedimentary records dated by astronomical tuning. Low values of relative palaeointensity during the Blake episode are estimated, but a relative maximum in the palaeofield intensity coeval with the complete reversal during the B2 interval was observed. Duration of the Blake geomagnetic excursion is 4.5kyr, two times lower than single excursions and slightly higher than the estimated diffusion time for the inner core (∼3kyr).

A carbon cycle coupled climate model of Neoproterozoic glaciation: Explicit carbon cycle with stochastic perturbations

[1] It has been suggested that a negative climate feedback may have operated during the Neoproterozoic Era as a consequence of the existence of a massive oceanic pool of dissolved organic carbon (DOC). As climate cooled so as to induce intense glaciation, the drawdown of oxygen into the Neoproterozoic ocean would have been enhanced because of the temperature dependence of the solubility of oxygen in seawater. Such increasing ventilation would have enhanced DOC remineralization, thus increasing the content of dissolved inorganic carbon (DIC) in the ocean. CO2 concentration in the atmosphere increases rapidly with DIC, thereby inhibiting further climate cooling. The model employed to illustrate the resulting climate dynamical behavior was an idealized one in which stochastic influence was assumed to be absent. However, such influence is expected to exist due to the action of processes that are not explicitly included in the model. Furthermore, the paleogeography assumed for the purpose of the published analyses was more appropriate to the Marinoan glaciation than to the earlier Sturtian event. In this paper, we fully investigate the stability of the system represented by the carbon cycle coupled climate model for both the Marinoan and Sturtian continental configurations and in the presence of stochastic perturbations. It is found that the hysteresis predicted by the ice sheet coupled model is sensitive to both continental configuration and to the strength of the negative feedback which arises due to carbon cycle coupling. Nevertheless, the very low frequency cyclic glaciation process predicted by the initial version of the model is found to persist in the presence of noise of significant amplitude. However, this cyclic behavior may be arrested entirely if the glaciation process were to result in insufficient alkalinity being delivered to the ocean basins. In this case the system would be expected to execute only a single excursion into and escape from the glacial state.

Annealing behavior of atomic layer deposited HfO2 films studied by synchrotron x-ray reflectivity and grazing incidence small angle scattering

New results are presented for the annealing behavior of ultrathin complementary-metal-oxide-semiconductor (CMOS) gate dielectric HfO2 films grown by atomic layer deposition (ALD). A series of ALD HfO2 dielectric films has been studied by a combination of x-ray reflectivity (XRR) and grazing-incidence small-angle x-ray scattering (GISAXS) measurements. By using these techniques together, we have shown that the surface, interfaces, and internal structure of thin ALD films can be characterized with unprecedented sensitivity. Changes in film thickness, film roughness, or diffuseness of the film/substrate interface as measured by XRR are correlated with the corresponding changes in the internal film nanostructure, as measured by GISAXS. Although the films are dense, an internal film structure is shown to exist, attributed primarily to ≈2 nm “missing island” porosity features close to the substrate; these are most likely associated with coalescence defects as a result of initial ALD growth, as they are not observed in the upper regions of the film. Some 8–9 nm heterogeneities are also present, which may indicate a widespread modulation in the film density pervading the entire film volume, and which likely also give rise to surface roughness. Comparison of the data between different scattering geometries and among a carefully designed sequence of samples has enabled important insights to be derived for the annealing behavior of the ALD HfO2 films. The main effects of single, brief, high temperature excursions to above 900 °C are to anneal out some of the fine voids and reduce the mean roughness and interfacial diffuseness of the film. These changes are indicative of densification. However, depending on the film thickness, the annealing behavior at temperatures between 650 and 800 °C is quite different for single excursion and cyclic anneals. Particularly for thin, just-coalesced films, XRR indicates marked increases in the film thickness and in the mean roughness/diffuseness dimension for cyclic anneals. GISAXS also shows an increase, rather than a reduction, in the void microstructure under these conditions. These changes in the film microstructure appear sufficient to overcome the expected film densification at elevated temperatures with implications for the gate dielectric performance of the films after extended high temperature exposure and cycling, as may occur during gate dielectric fabrication.

Carbon isotope chemostratigraphy of the Middle Riphean type section (Avzyan Formation, Southern Urals, Russia): Signal recovery in a fold-and-thrust belt

The Avzyan Formation of the southern Ural Mountains, Russia, forms part of the Middle Riphean (∼ 1300–1000 Ma) type section. Its age is constrained to be younger than 1348 Ma and older than 1080 Ma and thus may preserve all or part of the mid-Mesoproterozoic isotopic shift. This shift represents a significant reorganization of the carbon cycle and separates pre-1300 Ma carbonates with δ 13C near 0‰ from post-1200 Ma Mesoproterozoic successions having average δ 13C values greater than + 3.5‰. Because the Avzyan Formation is a significant reference section for the Mesoproterozoic and because it has the potential to record this mid-Mesoproterozoic shift, a chemostratigraphic profile was constructed for this strongly folded and thrust-faulted succession. Best-preserved δ 13C values from carbonates of the Avzyan Formation lie mainly between 0‰ and + 2‰, but the unit contains a single excursion, represented by several data points, to values greater than + 4‰. The chemostratigraphy of the Avzyan Formation does not provide a definitive match to a better-dated succession; however, the character of the carbon isotopic curve is most similar to that of the Dismal Lakes Group, arctic Canada, suggesting that the Avzyan Formation was deposited during the mid-Mesoproterozoic isotopic shift and may have an age near 1270 Ma. Best-preserved Sr isotopic values of 0.70587 are also consistent with a later Mesoproterozoic age.

Observations on densification of Al-Al2O3 composite powder compacts by pressure cycling

The effectiveness of pressure cycling on the consolidation of powder composites is investigated. Mixed Al and various amounts of Al2O3 powders were consolidated under static and cyclic pressure at room temperature in uniaxial consolidation experiments. The results showed that each pressure cycle increases green density and the cyclic effect is stronger when there is a relatively large volume fraction of Al2O3 powder. The compacts produced by pressure cycling have much higher strength than those produced with a single pressure excursion and the process ability of compacts should also improve via pressure cycling. Microscopic observations showed that greater uniformity is obtained in compacts by cyclic consolidation. The origin of the beneficial effect of pressure cycling is related to the deviatoric stresses generated by volumetric mismatch due to the different compressibilities of the phases.

Friction-induced vibration and noise generation of instrument panel material pairs

This study investigated the effect of various parameters of the friction–velocity relationship on the friction-induced vibration of simulated instrument panel components. The effect of subsystem stiffness and damping on the system response was also studied. A simple discretized model was utilized with subsystem properties that were intended to realistically model values of low, medium, and high stiffness components. Specifically, the metric of mean squared velocity was used as an indicator of the noise generated during the stick–slip process. It was found that the difference between the static and the asymptotic kinetic value of friction was the most important friction parameter in determining the resulting behavior. As stiffness and damping are increased, the mean squared velocity decreases. Additionally, results from single excursion tests on a variety of instrument panel material pairs showed good correlation between mean squared velocity and the difference in static and kinetic friction.

Axial transport and residence time of MSW in rotary kilns: Part II. Theoretical and optimal analyses

A novel particulate trajectory model (PTM) is developed to predict axial transport and dispersion of municipal solid wastes (MSW), based on the vector analysis on particle's gravity-induced axial displacement in a single excursion. Three parts of work are extended with respect to this PTM. First, the simplified formulas about mean residence time (MRT) and material volumetric flow (MVF) are derived by incorporating statistic-averaged analysis on all repeated excursions of solids within kiln into PTM. The correctional factors— ε t for MRT and ε f for MVF—are introduced to improve the model's validity under such practical cases, i.e. irregular MSW existence or internal-structure presence. Reasonable agreement is obtained between the empirical formulas and experiments with correlation factor in excess of 90% for all runs. Second, a stochastic PTM is extended to predict the residence time distribution (RTD) curves of segregated MSW by considering the probability of the rolling distance of individual particle. As for MSW, the main cause of axial dispersion is the segregation of rolling distance of solids, due to variation of MSW components, shapes and sizes. Finally, the optimization model for geometry design of a laboratory-scale rotary kiln pyrolyser of MSW is presented and the corresponding optimum solutions are provided.

On multiple-level excursions by stationary processes with deterministic peaks

A well-known property of stationary Gaussian processes is that the excursions over high levels (“peaks”) have a limiting parabolic shape, each determined by a single random parameter. This means, in particular, that (in the limit) the length of a single excursion above a high level determines the length of the (shorter) excursion above each higher level. In this paper we consider a general class of stationary processes with this property. Results of Leadbetter and Hsing (1990) for convergence of exceedance random measures are generalized to include multiple-level exceedances and developed further for the above class of processes. Specific application is made to stationary normal processes.

Dynamic properties of superconducting magnetic bearings

The potential use of YBa/sub 2/Cu/sub 3/O/sub 7/ as an active component in a magnetic bearing is being investigated. Although the load bearing capacity is high and increases with the square of the magnetic field trapped, the stiffness is low. Both the stiffness and the levitation height are a function of the loading history of the bearing. The authors have been investigating the effects of dynamic loading such as single large excursions from steady state loads and cyclically applied loads such as vibrations. Since a superconducting bearing has little inherent damping, cyclic loads applied at or near its natural frequency can have catastrophic effects. The information being gathered by the authors will be used to enable these effects to be mitigated in the bearing design process.

Optimal Control and Replacement with State-Dependent Failure Rate: Dynamic Programming

A class of stochastic control problems where the payoff depends on the running maximum of a diffusion process is described. The controller must make two kinds of decision: first, he must choose a work rate (this decision determines the rate of profit as well as the proximity of failure), and second, he must decide when to replace a deteriorated system with a new one. Preventive replacement is a realistic option if the cost for replacement after failure is larger than the cost of a preventive replacement. We focus on the profit and replacement cost for a single work cycle and solve the problem in two stages. First, the optimal feedback control (work rate) is determined by maximizing the payoff during a single excursion of a controlled diffusion away from the running maximum. This step involves the solution of the Hamilton-Jacobi-Bellman (HJB) partial differential equation. The second step is to determine the optimal replacement set. The assumption that failure occurs only on the set where the state is increasing implies that replacement is optimal only on this set. This leads to a simple formula for the optimal replacement level in terms of the value function.

Smooth radio emission and a new emission at Neptune

The Planetary Radio Astronomy (PRA) experiment [Warwick et al., 1977] on the spacecraft Voyager 2 observed three types of smooth emission: (1) Numerous recurrent episodes are modeled by filled emission cones from midlatitude conjugate sources. (2) An “equatorial” feature seen soon after closest approach includes electron cyclotron harmonic emission above the upper hybrid resonance, as well as smooth recurrent emission; its strange appearance is a result of rapid change in Voyager's magnetic latitude. (3) Unique “high‐latitude” emission is seen near closest approach during Voyager's single excursion to high north (+ ) magnetic latitude when fc, the electron cyclotron frequency at the spacecraft, lies in the observable range. The stronger component covers a broad band of frequencies above 2fc; its sensitivity to magnetic field identifies it as extraordinary (X) mode. The weaker component extends smoothly through f = fc and is identified as ordinary (O) mode. At each frequency f the observed sense of polarization reverses when f = 2fc.

Hazards of blood splashes.

When encountering novel environments, animals perform complex yet structured exploratory behaviors. Despite their typical structuring, the principles underlying exploratory patterns are still not sufficiently understood. Here we analyzed exploratory behavioral data from two modalities: whisking and locomotion in rats and mice. We found that these rodents maximized novelty signal-to-noise ratio during each exploration episode, where novelty is defined as the accumulated information gain. We further found that these rodents maximized novelty during outbound exploration, used novelty-triggered withdrawal-like retreat behavior, and explored the environment in a novelty-descending sequence. We applied a hierarchical curiosity model, which incorporates these principles, to both modalities. We show that the model captures the major components of exploratory behavior in multiple timescales: single excursions, exploratory episodes, and developmental timeline. The model predicted that novelty is managed across exploratory modalities. Using a novel experimental setup in which mice encountered a novel object for the first time in their life, we tested and validated this prediction. Further predictions, related to the development of brain circuitry, are described. This study demonstrates that rodents select exploratory actions according to a novelty management framework and suggests a plausible mechanism by which mammalian exploration primitives can be learned during development and integrated in adult exploration of complex environments.