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We mapped migration routes of migratory songbirds to the Neotropics by using light-level geolocators mounted on breeding purple martins (Progne subis) and wood thrushes (Hylocichla mustelina). Wood thrushes from the same breeding population occupied winter territories within a narrow east-west band in Central America, suggesting high connectivity of breeding and wintering populations. Pace of spring migration was rapid (233 to 577 kilometers/day) except for one individual (159 kilometers/day) who took an overland route instead of crossing the Gulf of Mexico. Identifying songbird wintering areas and migration routes is critical for predicting demographic consequences of habitat loss and climate change in tropical regions.

Ultrafast electron diffraction using MeV energy beams(MeV-UED) has enabled unprecedented scientific opportunities in the study of ultrafast structural dynamics in a variety of gas, liquid and solid state systems. Broad scientific applications usually pose different requirements for electron probe properties. Due to the complex, nonlinear and correlated nature of accelerator systems, electron beam property optimization is a time-taking process and often relies on extensive hand-tuning by experienced human operators. Algorithm based efficient online tuning strategies are highly desired. Here, we demonstrate multi-objective Bayesian active learning for speeding up online beam tuning at the SLAC MeV-UED facility. The multi-objective Bayesian optimization algorithm was used for efficiently searching the parameter space and mapping out the Pareto Fronts which give the trade-offs between key beam properties. Such scheme enables an unprecedented overview of the global behavior of the experimental system and takes a significantly smaller number of measurements compared with traditional methods such as a grid scan. This methodology can be applied in other experimental scenarios that require simultaneously optimizing multiple objectives by explorations in high dimensional, nonlinear and correlated systems. Due to the complex, nonlinear and correlated nature of accelerator systems, electron beam property optimisation is a time-consuming process. Here, the authors utilise multi-objective Bayesian active learning for speeding up online beam tuning at MeV ultrafast electron diffraction facility.

Focused ultrasound (FUS) is an innovative technology that delivers angled acoustic energy to a small target region. Previous FUS technology has demonstrated efficacy in applications such as tumor destruction, nerve modulation, and drug delivery in the brain. We investigated the effects of low-intensity FUS (LIFU) stimulation on the spinal cord and its ability to regulate mean arterial pressure (MAP). We found that LIFU stimulation on exposed rat spinal cord could modulate MAP, causing a decrease when applied at a lower thoracic level and an increase when applied at a lumbosacral level. We also found that shorter stimulation periods (30 s) were more effective in inducing a decrease in MAP than more extended stimulation periods (90 s). The time required to return to baseline for MAP was shown to increase with subsequent periods of FUS stimulation. FUS could enable non-pharmacological, spatially targeted MAP control, especially for impaired patients. Future applications of FUS neuromodulation extend into solutions for clinical blood pressure disorders, such as autonomic dysreflexia or chronic hypertension.

The ability to study chemical dynamics on ultrafast timescales has greatly advanced with the introduction of X-ray free electron lasers (XFELs) providing short pulses of intense X-rays tailored to probe atomic structure and electronic configuration. Fully exploiting the full potential of XFELs requires specialized experimental endstations along with the development of techniques and methods to successfully carry out experiments. The liquid jet endstation (LJE) at the Linac Coherent Light Source (LCLS) has been developed to study photochemistry and biochemistry in solution systems using a combination of X-ray solution scattering (XSS), X-ray absorption spectroscopy (XAS), and X-ray emission spectroscopy (XES). The pump–probe setup utilizes an optical laser to excite the sample, which is subsequently probed by a hard X-ray pulse to resolve structural and electronic dynamics at their intrinsic femtosecond timescales. The LJE ensures reliable sample delivery to the X-ray interaction point via various liquid jets, enabling rapid replenishment of thin samples with millimolar concentrations and low sample volumes at the 120 Hz repetition rate of the LCLS beam. This paper provides a detailed description of the LJE design and of the techniques it enables, with an emphasis on the diagnostics required for real-time monitoring of the liquid jet and on the spatiotemporal overlap methods used to optimize the signal. Additionally, various scientific examples are discussed, highlighting the versatility of the LJE.

North American birds that feed on flying insects are experiencing steep population declines, particularly long-distance migratory populations in the northern breeding range. We determine, for the first time, the level of migratory connectivity across the range of a songbird using direct tracking of individuals, and test whether declining northern populations have higher exposure to agricultural landscapes at their non-breeding grounds in South America. We used light-level geolocators to track purple martins, Progne subis, originating from North American breeding populations, coast-to-coast (n = 95 individuals). We show that breeding populations of the eastern subspecies, P. s. subis, that are separated by ca. 2000 km, nevertheless have almost completely overlapping non-breeding ranges in Brazil. Most (76%) P. s. subis overwintered in northern Brazil near the Amazon River, not in the agricultural landscape of southern Brazil. Individual non-breeding sites had an average of 91 per cent forest and only 4 per cent agricultural ground cover within a 50 km radius, and birds originating from declining northern breeding populations were not more exposed to agricultural landscapes than stable southern breeding populations. Our results show that differences in wintering location and habitat do not explain recent trends in breeding population declines in this species, and instead northern populations may be constrained in their ability to respond to climate change.

The massive forming industry in Germany produces around 1.4 million tons of parts every year, which are mainly used in safety-relevant areas such as the automotive industry. The production of these parts requires a considerable amount of energy, much of which remains unused and causes high CO2 emissions. An efficient approach to reduce these emissions and improve material utilization is cross-wedge rolling, which enables efficient material utilization but is limited by the so-called Mannesmann effect, which leads to unwanted material defects. This paper describes the development and validation of a safe design criterion for cross-wedge rolling tools in order to avoid material damage caused by the Mannesmann effect and thus increase resource efficiency in forging. Based on simulation-supported investigations and experimental tests, process maps are created for various materials. The validation is carried out both in an experimental test facility with real tools and in an industrial production facility, which leads to a significant reduction in excess material and CO2 emissions. The results show that the full resource potential of cross-wedge rolling can be exploited by optimizing process parameters and tool geometries.

Platelet homeostasis is dependent on a tight regulation of both platelet production and clearance. The small GTPase Rap1 mediates platelet adhesion and hemostatic plug formation. However, Rap1 signaling is also critical for platelet homeostasis as both Rap1 deficiency and uninhibited Rap1 signaling lead to marked thrombocytopenia in mice. Here, we investigated the mechanism by which deficiency in Rasa3, a critical negative regulator of Rap1, causes macrothrombocytopenia in mice. Despite marked morphological and ultrastructural abnormalities, megakaryocytes in hypomorphic Rasa3hlb/hlb (R3hlb/hlb) or Rasa3-/- mice demonstrated robust proplatelet formation in vivo, suggesting that defective thrombopoiesis is not the main cause of thrombocytopenia. Rather, we observed that R3hlb/hlb platelets became trapped in the spleen marginal zone/red pulp interface, with evidence of platelet phagocytosis by macrophages. Clearance of mutant platelets was also observed in the liver, especially in splenectomized mice. Platelet count and platelet life span in Rasa3-mutant mice were restored by genetic or pharmacological approaches to inhibit the Rap1/talin1/αIIbβ3 integrin axis. A similar pattern of splenic clearance was observed in mice injected with anti-αIIbβ3 but not anti-glycoprotein Ibα platelet-depleting antibodies. In summary, we describe a potentially novel, integrin-based mechanism of platelet clearance that could be critical for our understanding of select inherited and acquired thrombocytopenias.

Unraveling collective modes arising from coupled degrees of freedom is crucial for understanding complex interactions in solids and developing new functionalities. Unique collective behaviors emerge when two degrees of freedom, ordered on distinct length scales, interact. Polar skyrmions, three-dimensional electric polarization textures in ferroelectric superlattices, disrupt the lattice continuity at the nanometer scale with nontrivial topology, leading to previously unexplored collective modes. Here, using terahertz-field excitation and femtosecond x-ray diffraction, we discover subterahertz collective modes, dubbed “skyrons”, which appear as swirling patterns of atomic displacements functioning as atomic-scale gearsets. The key to activating skyrons is the use of the THz field that couples primarily to skyrmion domain walls. Momentum-resolved time-domain measurements of diffuse scattering reveal an avoided crossing in the dispersion relation of skyrons. Atomistic simulations and dynamical phase-field modeling provide microscopic insights into the three-dimensional crystallographic and polarization dynamics. The amplitude and dispersion of skyrons are demonstrated to be controlled by sample temperature and electric-field bias. The discovery of skyrons and their coupling with terahertz fields opens avenues for ultrafast control of topological polar structures. Polar skyrmions are nanoscale topological structures of electric polarizations. Their collective modes, dubbed as “skyrons”, are discovered by the terahertz-field-excitation, femtosecond x-ray diffraction measurements and advanced modeling.

Since its inauguration in 1976, the Super Proton Synchrotron (SPS) at CERN relies on a traveling wave system for particle acceleration instead of making use of standing wave cavities that are more common in circular accelerators. These traveling wave structures (TWSs) are essentially periodically loaded waveguides operated at a fundamental frequency of about 200 MHz. In the frame of the LHC injector upgrade project, the SPS accelerating system is presently improved to better cope with the increased beam intensity required for the future High Luminosity LHC era. The available accelerating voltage provided by the TWSs by means of radio-frequency (rf) generators is a fundamental and valuable input for machine operation and particle tracking codes used to simulate beam phenomena in the SPS. Measurement of the voltage with well known nonresonant and on-axis perturbation methods is however infeasible due to the extreme mechanical length of the SPS structures. It is shown that a good estimate of the rf voltage can be obtained from off-axis measurement samples in each accelerating gap in addition to the in- and output reflection coefficients of the structures. The rf voltage for the LHC proton beam delivered by the system configuration that was installed during the first and second exploitation run of the LHC is measured by this method, not including the beam loading. The impact on the fundamental accelerating mode and the rf voltage of additional higher order mode (HOM) couplers, which are also required for the upgrade of the acceleration system, is assessed by the proposed method as well.

The unique layer‐stacking in two‐dimensional (2D) van der Waals materials facilitates the formation of nearly degenerate phases of matter and opens novel routes for the design of low‐power, reconfigurable functional materials. Electrochemical ion intercalation between stacked layers offers a promising approach to stabilize bulk metastable phases and to explore the effects of extreme carrier doping and strain. However, in situ characterization methods to study the structural evolution and dynamical functional properties of these intercalated materials remains limited. Here a novel experimental platform is presented capable of simultaneously performing electrochemical lithium‐ion intercalation and multimodal ultrafast characterization of the lattice using both electron diffraction and nonlinear optical techniques. Using the layered semimetal WTe2 as a model system, the interlayer shear phonon mode that modulates stacking between 2Dlayers is probed, showing that small amounts of lithiation enhance the amplitude and lifetime of the phonon, contrary to expectations. This results from the dynamically fluctuating and anharmonic structure between nearly degenerate phases at room temperature, which can be stabilized by electronic carriers accompanying the inserted lithium ions. At high lithiation, the Td’ structure emerges and quenches the phonon response. This work defines new approaches for using electrochemistry to engineer the dynamic structure of 2D materials. A novel experimental platform is presented, capable of performing electrochemical lithiation of van der Waals materials and allowing for simultaneous multimodal characterization of the material using both ultrafast electron diffraction and nonlinear optical methods. By monitoring the behavior of the interlayer shear phonon in WTe2, light lithiation is found to stabilize the otherwise dynamically fluctuating and anharmonic structure at room‐temperature.