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The North American Cordillera formed by protracted subduction that led to the accretion of multiple exotic terranes during the Mesozoic. Subduction and terrane accretion are recorded throughout the Cordillera by fault-bounded mélange belts exposed between disparate terranes. South of the Denali fault in central Alaska, the Reindeer Hills Mélange (RHM) consists of pervasively sheared carbonate, ultramafic, and sandstone blocks in a shale and chert-breccia matrix. The presence of these oceanic rock types and correlation with nearby Cretaceous flysch has led to the interpretation that the RHM formed by subduction of oceanic lithosphere during the Cretaceous. However, the age of the RHM and its genetic relationship to surrounding terranes remain unclear. New structural and kinematic analysis along a ~5 km across-strike transect through the RHM reveals a steeply N-dipping penetrative cleavage, and asymmetric sandstone blocks in the shale matrix record distributed top-to-the-south shear. Detrital zircon U-Pb geochronology of grains taken from a sandstone block at the southern end of the transect present a dominant population of Silurian-Devonian grains that yield a youngest statistical population maximum depositional age of 416 +/- 6 Ma. Abundant Proterozoic grains ranging from 900-2000 Ma permit sediment input from peri-Laurentian sources, yet a distinctive population of 1450-1500 Ma grains may suggest input from Baltica basement or other Baltica-derived terranes recognized in the Cordillera (e.g., Alexander, Farewell). The new age data, along with Silurian-Devonian fossils from limestone blocks in the mélange and our recognition of Triassic diabase dikes that crosscut the mélange fabric, suggest that deposition and imbrication of Reindeer Hills clastic sediments took place in the Paleozoic. The new U-Pb data, Triassic mafic dikes, and published displacement estimates for the Denali fault suggest that the RHM correlates with the Mirror Creek Formation northeast of the Denali Fault in western Yukon, Canada, and may also have a link to Silurian-Devonian igneous rocks in the Alexander terrane of southeast Alaska. Altogether, the preliminary data presented here suggest that the RHM provides a record of early Devonian(?) subduction spatially associated with other Baltica-derived Cordilleran terranes. 

Interchange instability is known to drive fast radial transport of particles in Jupiter's inner magnetosphere. Magnetic flux tubes associated with the interchange instability often coincide with changes in particle distributions and plasma waves, but further investigations are required to understand their detailed characteristics. We analyze representative interchange events observed by Juno, which exhibit intriguing features of particle distributions and plasma waves, including Z‐mode and whistler‐mode waves. These events occurred at an equatorial radial distance of ∼9 Jovian radii on the nightside, with Z‐mode waves observed at mid‐latitude and whistler‐mode waves near the equator. We calculate the linear growth rate of whistler‐mode and Z‐mode waves based on the observed plasma parameters and electron distributions and find that both waves can be locally generated within the interchanged flux tube. Our findings are important for understanding particle transport and generation of plasma waves in the magnetospheres of Jupiter and other planetary systems. 

Abstract Interchange instability is known to drive fast radial transport of electrons and ions in Jupiter's inner and middle magnetosphere. In this study, we conduct a statistical survey to evaluate the properties of energetic particles and plasma waves during interchange events using Juno data from 2016 to 2023. We present representative examples of interchange events followed by a statistical analysis of the spatial distribution, duration and spatial extent. Our survey indicates that interchange instability is predominant atM‐shells from 6 to 26, peaking near 17 with an average duration of minutes and a correspondingM‐shell width of <∼0.05. During interchange events, the associated plasma waves, such as whistler‐mode, Z‐mode, and electron cyclotron harmonic waves exhibit a distinct preferential location. These findings provide valuable insights into particle transport and the source region of plasma waves in the Jovian magnetosphere, as well as in other magnetized planets within and beyond our solar system. 

Abstract Transport equations for electron thermal energy in the high- β e intracluster medium (ICM) are developed that include scattering from both classical collisions and self-generated whistler waves. The calculation employs an expansion of the kinetic electron equation along the ambient magnetic field in the limit of strong scattering and assumes whistler waves with low phase speeds V w ∼ v te / β e ≪ v te dominate the turbulent spectrum, with v te the electron thermal speed and β e ≫ 1 the ratio of electron thermal to magnetic pressure. We find: (1) temperature-gradient-driven whistlers dominate classical scattering when L c > L / β e , with L c the classical electron mean free path and L the electron temperature scale length, and (2) in the whistler-dominated regime the electron thermal flux is controlled by both advection at V w and a comparable diffusive term. The findings suggest whistlers limit electron heat flux over large regions of the ICM, including locations unstable to isobaric condensation. Consequences include: (1) the Field length decreases, extending the domain of thermal instability to smaller length scales, (2) the heat flux temperature dependence changes from T e 7 / 2 / L to V w nT e ∼ T e 1 / 2 , (3) the magneto-thermal- and heat-flux-driven buoyancy instabilities are impaired or completely inhibited, and (4) sound waves in the ICM propagate greater distances, as inferred from observations. This description of thermal transport can be used in macroscale ICM models. 

Recently expanded estimates for when humans arrived on Madagascar (up to approximately 10 000 years ago) highlight questions about the causes of the island's relatively late megafaunal extinctions (approximately 2000–500 years ago). Introduced domesticated animals could have contributed to extinctions, but the arrival times and past diets of exotic animals are poorly known. To conduct the first explicit test of the potential for competition between introduced livestock and extinct endemic megafauna in southern and western Madagascar, we generated new radiocarbon and stable carbon and nitrogen isotope data from the bone collagen of introduced ungulates (zebu cattle, ovicaprids and bushpigs, n = 66) and endemic megafauna (pygmy hippopotamuses, giant tortoises and elephant birds, n = 68), and combined these data with existing data from endemic megafauna (n = 282, including giant lemurs). Radiocarbon dates confirm that introduced and endemic herbivores briefly overlapped chronologically in this region between 1000 and 800 calibrated years before present (cal BP). Moreover, stable isotope data suggest that goats, tortoises and hippos had broadly similar diets or exploited similar habitats. These data support the potential for both direct and indirect forms of competition between introduced and endemic herbivores. We argue that competition with introduced herbivores, mediated by opportunistic hunting by humans and exacerbated by environmental change, contributed to the late extinction of endemic megafauna on Madagascar. 

Intuitive control of prostheses relies on training algorithms to correlate biological recordings to motor intent. The quality of the training dataset is critical to run-time performance, but it is difficult to label hand kinematics accurately after the hand has been amputated. We quantified the accuracy and precision of labeling hand kinematics for two different approaches: 1) assuming a participant is perfectly mimicking predetermined motions of a prosthesis (mimicked training), and 2) assuming a participant is perfectly mirroring their contralateral hand during identical bilateral movements (mirrored training). We compared these approaches in non-amputee individuals, using an infrared camera to track eight different joint angles of the hands in real-time. Aggregate data revealed that mimicked training does not account for biomechanical coupling or temporal changes in hand posture. Mirrored training was significantly more accurate and precise at labeling hand kinematics. However, when training a modified Kalman filter to estimate motor intent, the mimicked and mirrored training approaches were not significantly different. The results suggest that the mirrored training approach creates a more faithful but more complex dataset. Advanced algorithms, more capable of learning the complex mirrored training dataset, may yield better run-time prosthetic control. 

Abstract. The frontal flux balance of a medium-sized tidewater glacier in westernGreenland in the summer is assessed by quantifying the individual components(ice flux, retreat, calving, and submarine melting) through a combination ofdata and models. Ice flux and retreat are obtained from satellite data.Submarine melting is derived using a high-resolution ocean model informed bynear-ice observations, and calving is estimated using a record of calvingevents along the ice front. All terms exhibit large spatial variability alongthe ∼5&thinsp;km wide ice front. It is found that submarine melting accountsfor much of the frontal ablation in small regions where two subglacialdischarge plumes emerge at the ice front. Away from the subglacial plumes,the estimated melting accounts for a small fraction of frontal ablation.Glacier-wide, these estimates suggest that mass loss is largely controlled bycalving. This result, however, is at odds with the limited presence oficebergs at this calving front – suggesting that melt rates in regionsoutside of the subglacial plumes may be underestimated. Finally, we arguethat localized melt incisions into the glacier front can be significantdrivers of calving. Our results suggest a complex interplay of melting andcalving marked by high spatial variability along the glacier front. 

We describe use of a bidirectional neuromyoelectric prosthetic hand that conveys biomimetic sensory feedback. Electromyographic recordings from residual arm muscles were decoded to provide independent and proportional control of a six-DOF prosthetic hand and wrist—the DEKA LUKE arm. Activation of contact sensors on the prosthesis resulted in intraneural microstimulation of residual sensory nerve fibers through chronically implanted Utah Slanted Electrode Arrays, thereby evoking tactile percepts on the phantom hand. With sensory feedback enabled, the participant exhibited greater precision in grip force and was better able to handle fragile objects. With active exploration, the participant was also able to distinguish between small and large objects and between soft and hard ones. When the sensory feedback was biomimetic—designed to mimic natural sensory signals—the participant was able to identify the objects significantly faster than with the use of traditional encoding algorithms that depended on only the present stimulus intensity. Thus, artificial touch can be sculpted by patterning the sensory feedback, and biologically inspired patterns elicit more interpretable and useful percepts.