Environment-limited transfer of angular momentum in Bose liquids

Impurity motion in a many-body environment has been a central issue in the field of low-temperature physics for decades. In bosonic quantum fluids, the onset of a drag force experienced by point-like objects is due to collective environment excitations, driven by the exchange of linear momentum between the impurity and the many-body bath. In this work we consider a rotating impurity, with the aim of exploring how angular momentum is exchanged with the surrounding bosonic environment. In order to elucidate these issues, we employ a quasiparticle approach based on the angulon theory, which allows us to effectively deal with the non-trivial algebra of quantized angular momentum in the presence of a many-body environment. We uncover how impurity dressing by environmental excitations can establish an exchange channel, whose effectiveness crucially depends on the initial state of the impurity. Remarkably, we find that there is a critical value of initial angular momentum, above which this channel effectively freezes

Layer-specific control of inhibition by NDNF interneurons

Neuronal processing of external sensory input is shaped by internally generated top–down information. In the neocortex, top–down projections primarily target layer 1, which contains NDNF (neuron-derived neurotrophic factor)-expressing interneurons and the dendrites of pyramidal cells. Here, we investigate the hypothesis that NDNF interneurons shape cortical computations in an unconventional, layer-specific way, by exerting presynaptic inhibition on synapses in layer 1 while leaving synapses in deeper layers unaffected. We first confirm experimentally that in the auditory cortex, synapses from somatostatin-expressing (SOM) onto NDNF neurons are indeed modulated by ambient Gamma-aminobutyric acid (GABA). Shifting to a computational model, we then show that this mechanism introduces a distinct mutual inhibition motif between NDNF interneurons and the synaptic outputs of SOM interneurons. This motif can control inhibition in a layer-specific way and introduces competition between NDNF and SOM interneurons for dendritic inhibition onto pyramidal cells on different timescales. NDNF interneurons can thereby control cortical information flow by redistributing dendritic inhibition from fast to slow timescales and by gating different sources of dendritic inhibition

Global increase in the occurrence and impact of multiyear droughts

Persistent multiyear drought (MYD) events pose a growing threat to nature and humans in a changing climate. We identified and inventoried global MYDs by detecting spatiotemporally contiguous climatic anomalies, showing that MYDs have become drier, hotter, and led to increasingly diminished vegetation greenness. The global terrestrial land affected by MYDs has increased at a rate of 49,279 ± 14,771 square kilometers per year from 1980 to 2018. Temperate grasslands have exhibited the greatest declines in vegetation greenness during MYDs, whereas boreal and tropical forests have had comparably minor responses. With MYDs becoming more common, this global quantitative inventory of the occurrence, severity, trend, and impact of MYDs provides an important benchmark for facilitating more effective and collaborative preparedness toward mitigation of and adaptation to such extreme events

Reaction precursor-mediated formation of stable supercrystals in colloidal nanocrystal synthesis: PbTe case

Supercrystals represent three-dimensional orderings of colloidal nanocrystals (NCs), showcasing collective properties in photonics, phononics, and electronics applications.1,2 Recent studies have shown that such assemblies are directly produced during nanocrystal reactions.3–6 However, a fundamental understanding of in situ formed supercrystals that withstand typical NC purification processes remains underexplored, which is important for further use. Herein, we report the reaction precursor-mediated formation of stable PbTe supercrystals. Rationalizing the formation of these assemblies through small-angle x-ray scattering (SAXS) measurements, we unveil their formation mechanism. Our findings reveal that the supercrystal formation occurs in the presence of an excess of lead oleates in the crude solution. It should be noted that the formed supercrystals can be stabilized under specific conditions determined by the lead oleate cluster concentration, content of trioctylphosphine telluride (TOP-Te), NC size and the need of an annealing step at mild conditions. Furthermore, this approach allows for the continuous growth of a secondary phase within the supercrystal; for example in the case of PbTe supercrystals, a PbS shell can be grown on each PbTe NC constituent, resulting in core-shell PbTe-PbS supercrystals. Our work elucidates that reaction precursors play an important role in in situ SC formation and stabilization, implying the possibility of applying this knowledge to other NC reactions

Machine learning analysis of the factors influencing university-industry collaborations

In the dynamic arena of innovation, the relations between academia and industry are a keystone for breakthroughs and practical applications. Yet, the groundwork of these pivotal University-Industry (U-I) partnerships remains covered in complexity. This paper delves into these intricate relations, unraveling the factors that help successful collaborations. Grounded in the Resource-Based Theory, our study transcends traditional analytical boundaries, leveraging a neural network model to understand a comprehensive dataset from the UK’s Higher Education Statistics Agency, SCIMAGO Rankings, and Clarivate Publications. This novel approach helps to make clear the interplay of academic load, administrative support, scientific output, and university rank in sculpting U-I collaboration dynamics. Our findings suggest that reduced academic load and robust administrative support significantly bolster U-I collaborations. However, the influence of scientific output and university ranking is more nuanced, challenging the common belief. High scientific output, while indicative of expertise, doesn't always align with industry goals. Similarly, while higher-ranked universities could attract more collaborations, the benefits are not universal. This paper not only contributes to a deeper understanding of U-I collaborations, but also provides actionable insights for university administrators, policymakers, and industry leaders. In a world where innovation is key, understanding these collaborative dynamics is crucial for fostering partnerships that push the boundaries of research and practical application