Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
1,508
result(s) for
"Best, P."
Sort by:
Enabling the Global Response Force : access strategies for the 82nd Airborne Division
\"The Global Response Force (GRF) is built for rapid response to unforeseen or, more specifically, unplanned operations. Selected Army airborne forces provide a large portion of the GRF and are dependent on joint concepts for deployment and access. This study illustrates a method for determining the best access strategies given constraints in aircraft, intermediate staging bases, operational capabilities, and other factors. The study applies this method to each geographic combatant command and develops specific, tailored strategies for each. The access strategies are built from multiple analytic techniques: historical aircraft data and platform specifications to determine capabilities and limitations of the air fleet; several airfield databases, site reports, and expert judgments to determine probable intermediate staging base locations and their likely capabilities; multiple deployment concepts for access to minimize operational risks; and detailed geographic and operational analysis to determine global coverage and reach. In the end, we were able to deduce a preferred strategy for each of the combatant commands. Global access for the GRF is provided partially through the use of well-established staging bases but will necessarily rely on austere basing and complex deployment concepts for particular locations in multiple combatant commands. The study concludes with several recommendations to close those risks, which span the services, combatant commands, and joint staff\"--Back cover.
BOOK
One-Step Assembly of Coordination Complexes for Versatile Film and Particle Engineering
The development of facile and versatile strategies for thin-film and particle engineering is of immense scientific interest. However, few methods can conformally coat substrates of different composition, size, shape, and structure. We report the one-step coating of various interfaces using coordination complexes of natural polyphenols and Fe(III) ions. Film formation is initiated by the adsorption of the polyphenol and directed by pH-dependent, multivalent coordination bonding. Aqueous deposition is performed on a range of planar as well as inorganic, organic, and biological particle templates, demonstrating an extremely rapid technique for producing structurally diverse, thin films and capsules that can disassemble. The ease, low cost, and scalability of the assembly process, combined with pH responsiveness and negligible cytotoxicity, makes these films potential candidates for biomedical and environmental applications.
Journal Article
High-z Stellar Masses Can Be Recovered Robustly with JWST Photometry
Robust inference of galaxy stellar masses from photometry is crucial for constraints on galaxy assembly across cosmic time. Here, we test a commonly used spectral energy distribution (SED) fitting code using simulated galaxies from the Sphinx20 cosmological radiation hydrodynamics simulation with JWST NIRCam photometry forward-modeled with radiative transfer. Fitting the synthetic photometry with various star formation history models, we show that recovered stellar masses are, encouragingly, generally robust to within a factor of ∼3 for galaxies in the range M⋆ ∼ 107−109 M⊙ at z = 5−10. These results are in stark contrast to recent work claiming that stellar masses can be underestimated by as much as an order of magnitude in these mass and redshift ranges. However, while >90% of masses are recovered to within 0.5 dex, there are notable systematic trends, with stellar masses typically overestimated for low-mass galaxies (M⋆ ≲ 108 M⊙) and slightly underestimated for high-mass galaxies (M⋆ ≳ 109 M⊙). We demonstrate that these trends arise due to the SED fitting code poorly modeling the impact of strong emission lines on broadband photometry. These systematic trends, which exist for all star formation history parameterizations tested, have a tilting effect on the inferred stellar mass function, with the number densities of massive galaxies underestimated (particularly at the lowest redshifts studied) and the number densities of lower-mass galaxies typically overestimated. Overall, this work suggests that we should be optimistic about our ability to infer the masses of high-z galaxies observed with JWST (notwithstanding contamination from active galactic nuclei) but careful when modeling the impact of strong emission lines on broadband photometry.
Journal Article
Massive interstitial solid solution alloys achieve near-theoretical strength
Interstitials, e.g., C, N, and O, are attractive alloying elements as small atoms on interstitial sites create strong lattice distortions and hence substantially strengthen metals. However, brittle ceramics such as oxides and carbides usually form, instead of solid solutions, when the interstitial content exceeds a critical yet low value (e.g., 2 at.%). Here we introduce a class of massive interstitial solid solution (MISS) alloys by using a highly distorted substitutional host lattice, which enables solution of massive amounts of interstitials as an additional principal element class, without forming ceramic phases. For a TiNbZr-O-C-N MISS model system, the content of interstitial O reaches 12 at.%, with no oxides formed. The alloy reveals an ultrahigh compressive yield strength of 4.2 GPa, approaching the theoretical limit, and large deformability (65% strain) at ambient temperature, without localized shear deformation. The MISS concept thus offers a new avenue in the development of metallic materials with excellent mechanical properties.
Interstitials can substantially strengthen metals. Here the authors show a massive interstitial solid solution (MISS) approach enabling a model multicomponent alloy to achieve near-theoretical strength together with large deformability.
Journal Article
Near-theoretical strength and deformation stabilization achieved via grain boundary segregation and nano-clustering of solutes
Grain boundary hardening and precipitation hardening are important mechanisms for enhancing the strength of metals. Here, we show that these two effects can be amplified simultaneously in nanocrystalline compositionally complex alloys (CCAs), leading to near-theoretical strength and large deformability. We develop a model nanograined (TiZrNbHf)
98
Ni
2
alloy via thermodynamic design. The Ni solutes, which has a large negative mixing enthalpy and different electronegativity to Ti, Zr, Nb and Hf, not only produce Ni-enriched local chemical inhomogeneities in the nanograins, but also segregate to grain boundaries. The resultant alloy achieves a 2.5 GPa yield strength, together with work hardening capability and large homogeneous deformability to 65% compressive strain. The local chemical inhomogeneities impede dislocation propagation and encourage dislocation multiplication to promote strain hardening. Meanwhile, Ni segregates to grain boundaries and enhances cohesion, suppressing the grain growth and grain boundary cracking found while deforming the reference TiZrNbHf alloy. Our alloy design strategy thus opens an avenue, via solute decoration at grain boundaries combined with local chemical inhomogeneities inside the grains, towards ultrahigh strength and large plasticity in nanostructured alloys.
Grain boundary hardening and precipitation hardening are important mechanisms for enhancing the strength of metals. Here, these two effects are amplified simultaneously, by adding a suitable alloying element, leading to near-theoretical strength.
Journal Article
Neonatal Docosahexaenoic Acid in Preterm Infants and Intelligence at 5 Years
Children born very prematurely are deprived of maternal docosahexaenoic acid. This study shows an IQ at 5 years of age that was 3.5 points higher among children who had received neonatal DHA supplementation.
Journal Article
Coherent radio emission from a quiescent red dwarf indicative of star–planet interaction
Low-frequency (
ν
≲ 150 MHz) stellar radio emission is expected to originate in the outer corona at heights comparable to and larger than the stellar radius. Such emission from the Sun has been used to study coronal structure, mass ejections and space-weather conditions around the planets
1
. Searches for low-frequency emission from other stars have detected only a single active flare star
2
that is not representative of the wider stellar population. Here we report the detection of low-frequency radio emission from a quiescent star, GJ 1151—a member of the most common stellar type (red dwarf or spectral class M) in the Galaxy. The characteristics of the emission are similar to those of planetary auroral emissions
3
(for example, Jupiter’s decametric emission), suggesting a coronal structure dominated by a global magnetosphere with low plasma density. Our results show that large-scale currents that power radio aurorae operate over a vast range of mass and atmospheric composition, ranging from terrestrial planets to main-sequence stars. The Poynting flux required to produce the observed radio emission cannot be generated by GJ 1151’s slow rotation, but can originate in a sub-Alfvénic interaction of its magnetospheric plasma with a short-period exoplanet. The emission properties are consistent with theoretical expectations
4
–
7
for interaction with an Earth-size planet in an approximately one- to five-day-long orbit.
Low-frequency radio emission from a normally quiescent M dwarf star suggests a radio aurora generated by the interaction between the stellar corona and an undetected Earth-sized planet.
Journal Article
The population of M dwarfs observed at low radio frequencies
Coherent low-frequency (≲200 MHz) radio emission from stars encodes the conditions of the outer corona, mass-ejection events and space weather
1
–
5
. Previous low-frequency searches for radio-emitting stellar systems have lacked the sensitivity to detect the general population, instead largely focusing on targeted studies of anomalously active stars
5
–
9
. Here we present 19 detections of coherent radio emission associated with known M dwarfs from a blind flux-limited low-frequency survey. Our detections show that coherent radio emission is ubiquitous across the M dwarf main sequence, and that the radio luminosity is independent of known coronal and chromospheric activity indicators. While plasma emission can generate the low-frequency emission from the most chromospherically active stars of our sample
1
,
10
, the origin of the radio emission from the most quiescent sources is yet to be ascertained. Large-scale analogues of the magnetospheric processes seen in gas giant planets
3
,
11
,
12
probably drive the radio emission associated with these quiescent stars. The slowest-rotating stars of this sample are candidate systems to search for star–planet interaction signatures.
The authors present 19 detections of coherent low-frequency radio emission from M dwarfs using the Low Frequency Array. The sample includes both chromospherically active and quiescent stars, but radio luminosities are independent of coronal and chromospheric activity indicators.
Journal Article
Correction: Electron microscope loading and in situ nanoindentation of water ice at cryogenic temperatures
[This corrects the article DOI: 10.1371/journal.pone.0281703.].
Journal Article
Electron microscope loading and in situ nanoindentation of water ice at cryogenic temperatures
Interest in the technique of low temperature environmental nanoindentation has gained momentum in recent years. Low temperature indentation apparatuses can, for instance, be used for systematic measurements of the mechanical properties of ice in the laboratory, in order to accurately determine the inputs for the constitutive equations describing the rheologic behaviour of natural ice (i.e., the Glen flow law). These properties are essential to predict the movement of glaciers and ice sheets over time as a response to a changing climate. Herein, we introduce a new experimental setup and protocol for electron microscope loading and in situ nanoindentation of water ice. Preliminary testing on pure water ice yield elastic modulus and hardness measurements of 4.1 GPa and 176 MPa, respectively, which fall within the range of previously published values. Our approach demonstrates the potential of low temperature, in situ , instrumented nanoindentation of ice under controlled conditions in the SEM, opening the possibility for investigating individual structural elements and systematic studies across species and concentration of impurities to refine to constitutive equations for natural ice.
Journal Article