103 research outputs found
Identifying Potential Cropland Losses When Conserving 30% and 50% Earth with Different Approaches and Spatial Scales
Biodiversity conservation is the cornerstone for sustainable development. Bold conservation targets provide the last opportunities to halt the human-driven mass extinction. Recently, bold conservation targets have been proposed to protect 30% or 50% of Earth. However, little is known about its potential impacts on cropland. We identify potential cropland losses when 30% and 50% of global terrestrial area is given back to nature by 2030/2050, at three spatial scales (global, biome and country) and using two approaches (“nature-only landscapes” and “shared landscapes”). We find that different targets, applied scales and approaches will lead to different cropland losses: (1) At the global scale, it is possible to protect 50% of the Earth while having minimum cropland losses. (2) At biome scale, 0.64% and 8.54% cropland will be lost globally in 2030 and 2050 under the nature-only approach while by contrast, the shared approach substantially reduces the number of countries confronted by cropland losses, demanding only 0% and 2.59% of global cropland losses in 2030 and 2050. (3) At the national scale, the nature-only approach causes losses of 3.58% and 10.73% of global cropland in 2030 and 2050, while the shared approach requires 0.77% and 7.55% cropland in 2030 and 2050. Our results indicate that bold conservation targets could be considered, especially when adopting the shared approach, and we suggest adopting ambitious targets (protecting at least 30% by 2030) at the UN Biodiversity Conference (COP 15) to ensure a sustainable future for Earth
Reduction of the HIV Protease Inhibitor-Induced ER Stress and Inflammatory Response by Raltegravir in Macrophages
Background
HIV protease inhibitor (PI), the core component of highly active antiretroviral treatment (HAART) for HIV infection, has been implicated in HAART-associated cardiovascular complications. Our previous studies have demonstrated that activation of endoplasmic reticulum (ER) stress is linked to HIV PI-induced inflammation and foam cell formation in macrophages. Raltegravir is a first-in-its-class HIV integrase inhibitor, the newest class of anti-HIV agents. We have recently reported that raltegravir has less hepatic toxicity and could prevent HIV PI-induced dysregulation of hepatic lipid metabolism by inhibiting ER stress. However, little information is available as to whether raltegravir would also prevent HIV PI-induced inflammatory response and foam cell formation in macrophages. Methodology and Principal Findings
In this study, we examined the effect of raltegravir on ER stress activation and lipid accumulation in cultured mouse macrophages (J774A.1), primary mouse macrophages, and human THP-1-derived macrophages, and further determined whether the combination of raltegravir with existing HIV PIs would potentially exacerbate or prevent the previously observed activation of inflammatory response and foam cell formation. The results indicated that raltegravir did not induce ER stress and inflammatory response in macrophages. Even more interestingly, HIV PI-induced ER stress, oxidative stress, inflammatory response and foam cell formation were significantly reduced by raltegravir. High performance liquid chromatography (HPLC) analysis further demonstrated that raltegravir did not affect the uptake of HIV PIs in macrophages. Conclusion and Significance
Raltegravir could prevent HIV PI-induced inflammatory response and foam cell formation by inhibiting ER stress. These results suggest that incorporation of this HIV integrase inhibitor may reduce the cardiovascular complications associated with current HAART
Emerging spin-phonon coupling through cross-talk of two magnetic sublattices.
Many material properties such as superconductivity, magnetoresistance or magnetoelectricity emerge from the non-linear interactions of spins and lattice/phonons. Hence, an in-depth understanding of spin-phonon coupling is at the heart of these properties. While most examples deal with one magnetic lattice only, the simultaneous presence of multiple magnetic orderings yield potentially unknown properties. We demonstrate a strong spin-phonon coupling in SmFeO3 that emerges from the interaction of both, iron and samarium spins. We probe this coupling as a remarkably large shift of phonon frequencies and the appearance of new phonons. The spin-phonon coupling is absent for the magnetic ordering of iron alone but emerges with the additional ordering of the samarium spins. Intriguingly, this ordering is not spontaneous but induced by the iron magnetism. Our findings show an emergent phenomenon from the non-linear interaction by multiple orders, which do not need to occur spontaneously. This allows for a conceptually different approach in the search for yet unknown properties
Magnetically Tuned Continuous Transition from Weak to Strong Coupling in Terahertz Magnon Polaritons
Depending on the relative rates of coupling and dissipation, a light-matter coupled system is either in the weak- or strong-coupling regime. Here, we present a unique system where the coupling rate continuously increases with an externally applied magnetic field while the dissipation rate remains constant, allowing us to monitor a weak-to-strong coupling transition as a function of magnetic field. We observed a Rabi splitting of a terahertz magnon mode in yttrium orthoferrite above a threshold magnetic field of ~ 14 T. Based on a microscopic theoretical model, we show that with increasing magnetic field the magnons transition into magnon polaritons through an exceptional point, which will open up new opportunities for in situ control of non-Hermitian systems
Nonlinear coupled magnonics: Terahertz field-driven magnon upconversion
Tailored light excitation and nonlinear control of lattice vibrations have
emerged as powerful strategies to manipulate the properties of quantum
materials out of equilibrium. Generalizing the exploitation of coherent
phonon-phonon interactions to nonlinear couplings among other types of
collective modes would open unprecedented opportunities in the design of novel
dynamic functionalities in solids. For example, the collective excitations of
magnetic order - magnons - can efficiently transfer information via spin
current flow, and their coherent and nonlinear control would provide an
attractive route to achieve faster signal processing for next-generation
information technologies. Here, we discover that intense terahertz (THz) fields
can initiate processes of magnon upconversion via coherent magnon-magnon
interactions - a phenomenon that opens the paradigm of nonlinear coupled
magnonics. By using a suite of advanced spectroscopic tools, including a newly
demonstrated two-dimensional (2D) THz polarimetry technique enabled by
single-shot detection, we unveil the unidirectional nature of coupling between
distinct magnon modes of a canted antiferromagnet. Calculations of spin
dynamics further suggest that this coupling is a universal feature of
antiferromagnets with canted magnetic moments. These results demonstrate a
route to inducing desirable energy transfer pathways between coherent magnons
in solids and pave the way for a new era in the development of magnonic signal
processing devices
Anapole mediated giant photothermal nonlinearity in nanostructured silicon
Featured with a plethora of electric and magnetic Mie resonances, high index
dielectric nanostructures offer a versatile platform to concentrate
light-matter interactions at the nanoscale. By integrating unique features of
far-field scattering control and near-field concentration from radiationless
anapole states, here, we demonstrate a giant photothermal nonlinearity in
single subwavelength-sized silicon nanodisks. The nanoscale energy
concentration and consequent near-field enhancements mediated by the anapole
mode yield a reversible nonlinear scattering with a large modulation depth and
a broad dynamic range, unveiling a record-high nonlinear index change up to 0.5
at mild incident light intensities on the order of MW/cm2. The observed
photothermal nonlinearity showcases three orders of magnitude enhancement
compared with that of unstructured bulk silicon, as well as nearly one order of
magnitude higher than that through the radiative electric dipolar mode. Such
nonlinear scattering can empower distinctive point spread functions in confocal
reflectance imaging, offering the potential for far-field localization of
nanostructured Si with an accuracy approaching 40 nm. Our findings shed new
light on active silicon photonics based on optical anapoles
Emerging spin-phonon coupling through cross-talk of two magnetic sublattices
Typically, magnetic phenomena result from the spontaneous order of the sublattices. Here, the cross-talk of two magnetic ions gives rise to an intrinsic, yet non-spontaneous ordering and manifests as emergent strong spin-phonon coupling in SmFeO3. Many material properties such as superconductivity, magnetoresistance or magnetoelectricity emerge from the non-linear interactions of spins and lattice/phonons. Hence, an in-depth understanding of spin-phonon coupling is at the heart of these properties. While most examples deal with one magnetic lattice only, the simultaneous presence of multiple magnetic orderings yield potentially unknown properties. We demonstrate a strong spin-phonon coupling in SmFeO3 that emerges from the interaction of both, iron and samarium spins. We probe this coupling as a remarkably large shift of phonon frequencies and the appearance of new phonons. The spin-phonon coupling is absent for the magnetic ordering of iron alone but emerges with the additional ordering of the samarium spins. Intriguingly, this ordering is not spontaneous but induced by the iron magnetism. Our findings show an emergent phenomenon from the non-linear interaction by multiple orders, which do not need to occur spontaneously. This allows for a conceptually different approach in the search for yet unknown properties
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