Climate change and disturbance interact to alter landscape reflectivity (albedo) in boreal forests across a large latitudinal gradient in Siberia.

Boreal forests form the largest terrestrial biome globally. Climate change is expected to induce large changes in vegetation of high latitude ecosystems, but there is considerable uncertainty about where, when, and how those changes will occur. Such vegetation change produces major feedback to the climate system, including by modifying albedo (reflectivity).

New dynamic diamond anvil cell for time-resolved radial x-ray diffraction.

The dynamic diamond anvil cell (dDAC) is a recently developed experimental platform that has shown promise for studying the behavior of materials at strain rates ranging from intermediate to quasi-static and shock compression regimes. Combining dDAC with time-resolved x-ray diffraction (XRD) in the radial geometry (i.e.

Phase comparison and equation of state for TaO.

Tantalum pentoxide (TaO) is among the most technologically useful heavy transition metal oxides. Unfortunately, its crystal structure is the subject of long-standing and unresolved disagreement. Among other consequences, this uncertainty has made it impossible to formulate a robust high pressure equation of state for TaO.

A MHz X-ray diffraction set-up for dynamic compression experiments in the diamond anvil cell.

An experimental platform for dynamic diamond anvil cell (dDAC) research has been developed at the High Energy Density (HED) Instrument at the European X-ray Free Electron Laser (European XFEL). Advantage was taken of the high repetition rate of the European XFEL (up to 4.5 MHz) to collect pulse-resolved MHz X-ray diffraction data from samples as they are dynamically compressed at intermediate strain rates (≤10 s), where up to 352 diffraction images can be collected from a single pulse train.

Linking frass and insect phenology to optimize annual forest defoliation estimation.

It is often logistically impractical to measure forest defoliation events in the field due to seasonal variability in larval feeding phenology (e.g., start, peak, and end) in any given year.

Of clockwork and catastrophes: advances in spatiotemporal dynamics of forest Lepidoptera.

We applied a systematic global literature survey from the last 2.5 years on spatiotemporal population dynamics - broadly defined - of Lepidopteran forest pests. Articles were summarized according to domain-specific (planetary ecology - remote sensing, evolutionary ecology - genetics and genomics, and theoretical ecology - modeling) contributions to contemporary investigation of the above theme.

CO laser heating system for in situ radial x-ray absorption at 16-BM-D at the Advanced Photon Source.

We present a portable CO laser heating system for in situ x-ray absorption spectroscopy (XAS) studies at 16-BM-D (High Pressure Collaborative Access Team, Advanced Photon Source, Argonne National Laboratory). Back scattering optical measurements are made possible by the implementation of a Ge beamsplitter. Optical pyrometry is conducted in the near-infrared, and our temperature measurements are free of chromatic aberration due to the implementation of the peak-scaling method [A.

Cinema:Snap: Real-time tools for analysis of dynamic diamond anvil cell experiment data.

We developed tools and a workflow for real-time analysis of data from dynamic diamond anvil cell experiments performed at user light sources. These tools allow users to determine the phases of matter observed during the compression of materials in order to make decisions during an experiment to improve the quality of experimental results and maximize the use of scarce experimental facility time. The tools fill a gap in dynamic compression data analysis tools that are real-time, are flexible to the needs of high-pressure scientists, connect to automated processing of results, can be easily incorporated into workflows with existing tools and data formats, and support remote experimental data analysis workflows.

Multi-phase equation of state of ultrapure hafnium to 120 GPa.

Hafnium (Hf) is an industrially important material due to its large neutron absorption cross-section and its high corrosion resistance. When subjected to high pressure, Hf phase transforms from its hexagonal close packed α-Hf phase to the hexagonal ω-Hf phase. Upon further compression, ω-Hf phase transforms to the body centered cubic β-Hf phase.

Novel experimental setup for megahertz X-ray diffraction in a diamond anvil cell at the High Energy Density (HED) instrument of the European X-ray Free-Electron Laser (EuXFEL).

The high-precision X-ray diffraction setup for work with diamond anvil cells (DACs) in interaction chamber 2 (IC2) of the High Energy Density instrument of the European X-ray Free-Electron Laser is described. This includes beamline optics, sample positioning and detector systems located in the multipurpose vacuum chamber. Concepts for pump-probe X-ray diffraction experiments in the DAC are described and their implementation demonstrated during the First User Community Assisted Commissioning experiment.

X-ray Free Electron Laser-Induced Synthesis of ε-Iron Nitride at High Pressures.

The ultrafast synthesis of ε-FeN in a diamond-anvil cell (DAC) from Fe and N under pressure was observed using serial exposures of an X-ray free electron laser (XFEL). When the sample at 5 GPa was irradiated by a pulse train separated by 443 ns, the estimated sample temperature at the delay time was above 1400 K, confirmed by transformation of α- to γ-iron. Ultimately, the Fe and N reacted uniformly throughout the beam path to form FeN, as deduced from its established equation of state (EOS).

Restoring open canopy pine barrens from the ground up: Repeated burns correspond with increased soil hydraulic conductivity.

Prescribed fire is widely used for ecosystem restoration, yet the mechanisms that determine its effectiveness remain poorly characterized. Because soil hydrology influences ecosystem processes like erosion, runoff, and plant competition, it is important to understand how fire affects soil hydrology. A systematic approach to understanding relationships among vegetation, topography, and fire is needed to advance knowledge of how fire influences soil properties that in turn affect restoration success.

The Vision of Managing for Pest-Resistant Landscapes: Realistic or Utopic?

Purpose Of Review: Forest managers have long suggested that forests can be made more resilient to insect pests by reducing the abundance of hosts, yet this has rarely been done. The goal of our paper is to review whether recent scientific evidence supports forest manipulation to decrease vulnerability. To achieve this goal, we first ask if outbreaks of forest insect pests have been more severe in recent decades.

A Physics-Based Signal Processing Approach for Noninvasive Ultrasonic Characterization of Multiphase Oil-Water-Gas Flows in a Pipe.

A signal processing technique is presented for determining the composition of multiphase oil-water-gas flow in a pipe using noninvasive ultrasonic speed of sound measurements from a transmitter-receiver pair bonded to diametrically opposite sides of a pipe. A linear chirp excitation is used to send broadband ultrasonic energy that propagates in two paths from transmitter to receiver such as: 1) a wave through the pipe wall and then the multiphase mixture and 2) ultrasonic guided waves along the pipe wall in the circumferential direction. As the ultrasonic attenuation of the multiphase mixture increases, the amplitude of the signal through the fluid mixture decreases relative to that of circumferential guided waves, making it difficult to determine the time of arrival of the fluid-path signal and, hence, the speed of sound in the mixture.

A broadband wavelet implementation for rapid ultrasound pulse-echo time-of-flight measurements.

A broadband wavelet approach to ultrasonic pulse-echo time-of-flight measurements is described. The broadband approach significantly reduces the time required for frequency-dependent pulse-echo measurements, enabling studies of dynamic systems ranging from biological systems to solid-state phase transitions. The described broadband approach is demonstrated in parallel with the more traditional frequency stepping approach to perform ultrasound time-of-flight measurements inside a large volume Paris-Edinburgh press in situ at a synchrotron source.

Experimental melting curve of zirconium metal to 37 GPa.

In this report, we present results of high-pressure experiments probing the melt line of zirconium (Zr) up to 37 GPa. This investigation has determined that temperature versus laser power curves provide an accurate method to determine melt temperatures. When this information is combined with the onset of diffuse scattering, which is associated with the melt process, we demonstrate the ability to accurately determine the melt boundary.

Room-temperature compression and equation of state of body-centered cubic zirconium.

Zirconium (Zr) has properties conducive to nuclear applications and exhibits complex behavior at high pressure with respect to the effects of impurities, deviatoric stress, kinetics, and grain growth which makes it scientifically interesting. Here, we present experimental results on the 300 K equation of state of ultra-high purity Zr obtained using the diamond-anvil cell coupled with synchrotron-based x-ray diffraction and electrical resistance measurements. Based on quasi-hydrostatic room-temperature compression in helium to pressure P  =  69.

Forecasting effects of tree species reintroduction strategies on carbon stocks in a future without historical analog.

American chestnut (Castanea dentata) was once an important component forests in the central Appalachians (USA), but it was functionally extirpated nearly a century ago. Attempts are underway to reintroduce blight-resistant chestnut to its former range, but it is uncertain how current forest composition, climate, and atmospheric changes and disturbance regimes will interact to determine future forest dynamics and ecosystem services. The combination of novel environmental conditions (e.

Modelling moose-forest interactions under different predation scenarios at Isle Royale National Park, USA.

Loss of top predators may contribute to high ungulate population densities and chronic over-browsing of forest ecosystems. However, spatial and temporal variability in the strength of interactions between predators and ungulates occurs over scales that are much shorter than the scales over which forest communities change, making it difficult to characterize trophic cascades in forest ecosystems. We applied the LANDIS-II forest succession model and a recently developed ungulate browsing extension to model how the moose population could interact with the forest ecosystem of Isle Royale National Park, USA, under three different wolf predation scenarios.

High frequency signal acquisition using a smartphone in an undergraduate teaching laboratory: Applications in ultrasonic resonance spectra.

A simple and inexpensive approach to acquiring signals in the megahertz frequency range using a smartphone is described. The approach is general, applicable to electromagnetic as well as acoustic measurements, and makes available to undergraduate teaching laboratories experiments that are traditionally inaccessible due to the expensive equipment that are required. This paper focuses on megahertz range ultrasonic resonance spectra in liquids and solids, although there is virtually no upper limit on frequencies measurable using this technique.

The acoustic nonlinearity parameter in Fluorinert up to 381 K and 13.8 MPa.

This work reports on the determination of the acoustic nonlinearity parameter, B/A, from measured sound speed data, in Fluorinert FC-43 at temperatures up to 381 K and pressures up to 13.8 MPa using the thermodynamic method. Sound speed was measured using Swept Frequency Acoustic Interferometry at 11 pressures between ambient and 13.

Life-stage differences in spatial genetic structure in an irruptive forest insect: implications for dispersal and spatial synchrony.

Dispersal determines the flux of individuals, energy and information and is therefore a key determinant of ecological and evolutionary dynamics. Yet, it remains difficult to quantify its importance relative to other factors. This is particularly true in cyclic populations in which demography, drift and dispersal contribute to spatio-temporal variability in genetic structure.

Integrating ecophysiology and forest landscape models to improve projections of drought effects under climate change.

Fundamental drivers of ecosystem processes such as temperature and precipitation are rapidly changing and creating novel environmental conditions. Forest landscape models (FLM) are used by managers and policy-makers to make projections of future ecosystem dynamics under alternative management or policy options, but the links between the fundamental drivers and projected responses are weak and indirect, limiting their reliability for projecting the impacts of climate change. We developed and tested a relatively mechanistic method to simulate the effects of changing precipitation on species competition within the LANDIS-II FLM.

Evaluation of the transmission line model for couplant layer corrections in pulse-echo measurements.

An acoustic couplant layer plays an integral role in many ultrasonic nondestructive testing and material characterization applications. It is important to account for this layer for accurate time-delay measurements. In pulse-echo measurements, the couplant layer can be accounted for by modeling the frequency dependence of phase delay.

Adhesion of explosives.

It is of increasing importance to understand how explosive particles adhere to surfaces in order to understand how to remove them for detection in airport or other security settings. In this study, adhesion forces between royal demolition explosive (cyclotrimethylenetrinitramine) (RDX), pentaerythritol tetranitrate (PETN), and trinitrotoluene (TNT) in their crystalline forms and aluminum coupons with three finishes, acrylic melamine (clear coating), polyester acrylic melamine (white coating) automotive finishes, and a green military-grade finish, were measured and modeled. The force measurements were performed using the atomic force microscopy (AFM)-based colloidal probe microscopy (CPM) method.