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Ice motion and boundaries are critical information for ice sheet models that project ice evolution in a warming climate. We present four historical, continent‐wide, maps of Antarctic‐wide ice motion and boundaries for the time period 1995–2022. The results reveal no change in the interior region of East Antarctica, iceberg detachments at ice shelf fronts, and widespread glacier speedup that propagates 100 km's inland in West Antarctica and the Antarctic Peninsula. Speedup affects the entire drainage of the Amundsen Sea Embayment sector; the entire west coast of the Antarctic Peninsula down to GeorgeVI Ice Shelf; the east coast down to Larsen C Ice Shelf; Getz Ice Shelf, Hull and Land glaciers in West Antarctica; Matusevitch, Ninnis, Mertz and Denman glaciers, glaciers in Porpoise and Vincennes Bay; and Robert, Wilma and Rayner glaciers in Enderby Land, in East Antarctica. We attribute the observed glacier changes to increased melting by warmer ocean waters. Plain Language Summary: Ice velocity is a fundamental variable of glacier evolution that governs the transfer of mass from the ice sheets to the ocean. It is best measured from satellite platforms but long time series require combination of multiple satellite data of various performance levels and incomplete spatial coverage. We assembled the first set of continent‐wide mosaics using 2–5 years of data in each period to maximize spatial coverage and detect changes in ice dynamics over the entire continent. The results reveal no signal over most of the interior but important changes at the coast concentrated along channels occupied by outlet glaciers. In the Amundsen Sea Embayment sector of West Antarctica, changes are pervasive over the entire drainage, which indicates that the coastal forcing from the ocean affects the entire ice sheet. The products reveal precise areas of rapid change in the West and East coasts of the Antarctica Peninsula, and in West and East Antarctica. These observations will help constrain ice sheet models in charge of reconstructing ice sheet past changes and projecting its evolution in a changing climate. Key Points: We present historical, continent‐wide, mosaics of Antarctic ice motion using a suite of satellite sensors spanning 28 yearsWe report areas of accelerated flow stretching over 100 km's from the coast and the entire drainage of the Amundsen Sea Embayment sectorThe observed, ongoing, detailed glacier changes will help constrain ice sheet numerical models in charge of reconstruction and projection [ABSTRACT FROM AUTHOR]

Humboldt Gletscher is a 100‐km wide, slow‐moving glacier in north Greenland which holds a 19‐cm global sea level equivalent. Humboldt has been the fourth largest contributor to sea level rise since 1972 but the cause of its mass loss has not been elucidated. Multi‐beam echo sounding data collected in 2019 indicate a seabed 200 m deeper than previously known. Conductivity temperature depth data reveal the presence of warm water of Atlantic origin at 0°C at the glacier front and a warming of the ocean waters by 0.9 ± 0.1°C since 1962. Using an ocean model, we reconstruct grounded ice undercutting by the ocean, combine it with calculated retreat caused by ice thinning to floatation, and are able to fully explain the observed retreat. Two thirds of the retreat are caused by undercutting of grounded ice, which is a physical process not included in most ice sheet models. Plain Language Summary: Humboldt Gletscher is the widest glacier in Greenland, slow moving, and terminating in shallow waters in its southern half, but grounded 200 m deeper than previously known in its northern half, with a submarine trough extending more than 100 km inland. The glacier has been retreating at 0.6 km/year and contributing significantly to sea level rise. We attribute the retreat to undercutting of grounded ice by warmer ocean waters combined with a retreat caused by ice thinning to floatation sooner due to glacier speed up. The glacier, which hosts an ice volume equivalent to a 19‐cm global sea level, will remain a major contributor to sea level rise this Century. Key Points: The 100‐km wide Humboldt Gletscher holds a 19‐cm sea level rise equivalent, lost 161 billion tons of mass, and retreated 13 km since 1972Warm waters at 0°C flood a 350–400 m deep trough on its northern flank that remains below sea level more than 100 km inlandWe explain the glacier retreat as 70% from ocean‐induced undercutting and 30% from thinning‐induced retreat [ABSTRACT FROM AUTHOR]

Relatively little is known about the physical mechanisms that drive the dynamics of the East Antarctic outlet glaciers. Here we conduct a remote-sensing investigation of the Polar Record Glacier (PRG), East Antarctica to analyze its ice flow acceleration, ice front variations and ice surface melting. Ice flow speeds at PRG increased by up to 15% from 2005 to 2015, with substantial interannual fluctuations. The ice velocities also showed seasonal variations, accelerating by up to 9% between September and January. Multiple mechanisms contribute to the observed seasonal variations: the initial acceleration may result from the lost back-stress provided by the sea ice in the austral spring and the later speedup relate to the surface meltwater that leads to weakened ice shelf and shear margins. The sensitivity of the PRG to oceanic forcing is confirmed by comparing the secular ice velocity increases with ocean temperatures. These measurements suggest that the dynamics of East Antarctic ice shelves are sensitive to melt at both the surface and base, at a range of timescales. [ABSTRACT FROM AUTHOR]

Rapid changes in thickness and velocity have been observed at many marine-terminating glaciers in Greenland, impacting the volume of ice they export, or discharge, from the ice sheet. While annual estimates of ice-sheet-wide discharge have been previously derived, higher-resolution records are required to fully constrain the temporal response of these glaciers to various climatic and mechanical drivers that vary in sub-annual scales. Here we sample outlet glaciers wider than 1 km (N=230) to derive the first continuous, ice-sheet-wide record of total ice sheet discharge for the 2000–2016 period, resolving a seasonal variability of 6 %. The amplitude of seasonality varies spatially across the ice sheet from 5 % in the southeastern region to 9 % in the northwest region. We analyze seasonal to annual variability in the discharge time series with respect to both modeled meltwater runoff, obtained from RACMO2.3p2, and glacier front position changes over the same period. We find that year-to-year changes in total ice sheet discharge are related to annual front changes (r2=0.59 , p=10-4) and that the annual magnitude of discharge is closely related to cumulative front position changes (r2=0.79), which show a net retreat of >400 km, or an average retreat of >2 km, at each surveyed glacier. Neither maximum seasonal runoff or annual runoff totals are correlated to annual discharge, which suggests that larger annual quantities of runoff do not relate to increased annual discharge. Discharge and runoff, however, follow similar patterns of seasonal variability with near-coincident periods of acceleration and seasonal maxima. These results suggest that changes in glacier front position drive secular trends in discharge, whereas the impact of runoff is likely limited to the summer months when observed seasonal variations are substantially controlled by the timing of meltwater input. [ABSTRACT FROM AUTHOR]

Repeat image feature tracking is commonly used to measure glacier surface motion from pairs of images, most often utilizing normalized cross correlation (NCC). The multiple-image multiple-chip (MIMC) algorithm successfully employed redundant matching (i.e., repeating the matching process over each area using varying combinations of settings) to increase the matching success rate. Due to the large number of repeat calculations, however, the original MIMC algorithm was slow and still prone to failure in areas of high shearing flow. Here, we present several major updates to the MIMC algorithm that increase both the speed and the matching success rate. First, we include additional redundant measurements by swapping the image order and matching direction; a process we term quadramatching. Second, we utilize a priori ice velocity information to confine the NCC search space through a system we term dynamic linear constraint, which substantially reduces the computation time and increases the rate of successful matches. Additionally, we develop a novel postprocessing algorithm, pseudosmoothing, to determine the most probable displacement. Our tests reveal the complementary and multiplicative nature of these upgrades in their improvement in the overall MIMC performance. [ABSTRACT FROM PUBLISHER]

The extent of glacier terminus displacement is instrumental in investigations of natural or artificial geographic changes. Its importance to earth science and engineering is reflected in the considerable efforts that have been devoted to the development of several boundary displacement analysis methods. Among the methods, the buffering-based approach compares favorably with other approaches in objectivity and robustness. However, it does not consider the relative positions of boundaries, because its buffering operation cannot determine features' relative directions. This limitation incurs inaccurate calculation results – underestimation of mean shifts and overestimation of shape variations, especially when the two compared boundaries intersect. Discrete displacement analysis (DDA), an alternative method that considers given geographic objects as a set of a finite number of points, is proposed here. In a series of tests carried out, including Jakobshavn glacier's calving front, DDA was found to correctly calculate mean shift and shape variation even in cases where the conventional buffering-based method failed. Moreover, this approach is independent of the dimension of space in which it is implemented, and thus is expected to be utilized for analysis of 3D geographic object displacement. [ABSTRACT FROM AUTHOR]

Only ∼20% of a vehicle's fuel consumption is used for overcoming air drag force and friction with the road. Vibration energy produced during driving is dissipated by shock absorbers in the vehicle suspension. A new Piezoelectric Energy-Harvesting Shock Absorber (PEHSA) system for vehicles has been developed to act as an energy harvester that converts vibration energy to electrical energy. Cylindrical piezoelectric transducers are combined with the cylinder of the shock absorber to generate electricity from changes in fluid pressure produced by piston vibrations. A multiphysics simulation was performed using COMSOL Multiphysics to determine the characteristics of the PEHSA system. [ABSTRACT FROM AUTHOR]

This paper represented driving characteristic of a thin-type ultrasonic motor by fabricating and utilizing two kinds of drivers which could generate sinusoidal wave, square wave, respectively. A thin brass plate was used as a cross shaped vibrator and sixteen ceramic plates were attached on upper and bottom side of the brass plate. From the thin stator, elliptical displacements of the four contact tips were obtained. When two harmonic voltages which have 90° phase difference were applied to the ceramics, the symmetric and anti-symmetric displacements were generated at inside of the tips to make the elliptical motion. A finite element analysis (ATILA) was used for simulating the motional pattern of contact tips of the stator. The characteristics of the motor such as speed, torque, and current consumption were measured by applying sinusoidal waves through driving equipment which composed of function generator and power amplifier. As a result, the speed and the torque changed linearly at both driving frequency of 88.6 ∼ 87.6[kHz] and voltage of 24∼36[V]. Two-drivers which generate sinusoidal waves and square waves were designed and compared through some experiments in order to be put to practical use. In conclusion, the drivers had similar characteristic of speed-torque at alike frequency and voltage range. The square wave driver was recommended to control the motor linearly among two drivers by reason of practical use and simplification of driver. [ABSTRACT FROM AUTHOR]

The Piezoelectric generator for energy harvesting is usually using rectangular type unimorph or bimorph. In this paper, the characteristic of the piezoelectric generator which has a circular type bender was studied for more efficiently converting the mechanical energy to electrical energy than the rectangular type. The generator consisted of circular type vibrating plate, thin piezoelectric ceramics, stub and mass. The generator was simulated with FEM(finite element method) program as changing size of each part. When the radius of the piezoelectric ceramics and the elastic body were increased and the diameter of the vibrating plate was increased, the resonant frequency was decreased. And the output voltage was increased when the radius of the elastic body was increased. The output voltage was also affected by the distance which is the mass position from center of unimorph. The piezoelectric generator was fabricated from these simulated results. The output power was 4.3[mW] when the weight of mass was 7.2g. [ABSTRACT FROM AUTHOR]

We explore and compare the capabilities and limitations of different optical sensors (Sentinel-2/ESA, Landsat 7/8/USGS, Ven μ s/CNES-ISA, Pléiades/AirbusD&S and Planet Labs images) for mapping the surface speeds of mountain glaciers on a regional scale. We present here our automated workflow designed to download data from institutional or commercial servers, prepare images, launch the feature tracking algorithm, calibrate glacier surface speeds, and our post-processing treatment to obtain filtered and time-averaged velocity maps. We applied our methodology to three regions: (1) the European alps; (2) the Peruvian Cordillera Blanca; and (3) the Southern Alps of New Zealand for years 2017 and 2018 and quantified ice velocity for every possible repeat cycle from few days up to 400 days. For these regions, we demonstrate the ability of our processing chain to derive precise time-averaged ice flow maps. The statistical analysis of the results provided by each individual repeat cycles shows that velocity mapping from Sentinel-2 is about twice more precise than that from Landsat 7/8. If Sentinel-2 captures more details than Landsat, some of the smallest glaciers (<250 m wide) remain challenging. Given the estimated precision for Sentinel-2, we also conclude that velocity fluctuations of the order of 10 m/yr can only be captured with repeat cycles longer than 60 days. Comparing Sentinel-2 with Pléiades, Planet and Ven μ s imagery, we finally highlight the advantages of high-resolution sensors to map glacier surface speed with finer details in space and time. [ABSTRACT FROM AUTHOR]

In the eukaryotic circadian clock machinery, negative feedback repression of CLOCK (CLK) and BMAL1 transcriptional activity by PERIOD (PER) and CRYPTOCHROME (CRY) underlies the basis for 24 h rhythmic gene expression. Thus, precise regulation of the time-dependent nuclear entry of circadian repressors is crucial to generating normal circadian rhythms. Here, we sought to identify novel kinase(s) that regulate nuclear entry of mammalian CRY1 (mCRY1) with an unbiased screening using red fluorescent protein (RFP)-tagged human kinome expression plasmids in mammalian cells. Transient expression of human vaccinia-related kinase 3 (hVRK3) reduced the nuclear presence of mCRY1. hVRK3 expression also induced alterations in the subcellular localization of other core clock proteins, including mCRY2, mPER2, and BMAL1. In contrast, the subcellular localization of mCLK was not changed. Given that singly expressed mCLK mostly resides in the cytoplasm and that nuclear localization sequence (NLS) mutation of hVRK3 attenuated the effect of hVRK3 co-expression on subcellular localization, ectopically expressed hVRK3 presumably reduces the retention of proteins in the nucleus. Finally, downregulation of hvrk3 using siRNA reduced the amplitude and lengthened the period of the cellular bioluminescence rhythm. Taken together, these data suggest that VRK3 plays a role in setting the amplitude and period length of circadian rhythms in mammalian cells. [ABSTRACT FROM AUTHOR]

The central mechanisms coordinating growth and sexual maturation are well conserved across invertebrates and vertebrates. Although mutations in the gene encoding makorin RING finger protein 3 ( mkrn3 ) are associated with central precocious puberty in humans, a causal relationship has not been elucidated. Here, we examined the role of mkrn1 , a Drosophila ortholog of mammalian makorin genes, in the regulation of developmental timing. Loss of MKRN1 in mkrn1 exS prolonged the 3 rd instar stage and delayed the onset of pupariation, resulting in bigger size pupae. MKRN1 was expressed in the prothoracic gland, where the steroid hormone ecdysone is produced. Furthermore, mkrn1 exS larvae exhibited reduced mRNA levels of phantom, which encodes ecdysone-synthesizing enzyme and E74, which is a downstream target of ecdysone. Collectively, these results indicate that MKRN1 fine-tunes developmental timing and sexual maturation by affecting ecdysone synthesis in Drosophila. Moreover, our study supports the notion that malfunction of makorin gene family member, mkrn3 dysregulates the timing of puberty in mammals.