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The rapid advancement and high integration of photonic integrated circuits (PICs) have enabled energy-efficient and fast computation in compact chip designs. A fundamental challenge in both classical and quantum information processing is the ability to create light wavefronts with complex spatial amplitude and phase distributions. Traditional methods that involve splitting light into multiple channels and modulating each one individually typically lead to chip area and power waste. We introduce a compact programmable PIC capable of generating arbitrary complex spatial states in a power-conserving manner. The proposed system harnesses multipath interference in an interlaced arrangement of phase modulator arrays and photonic lattices to transform excitation from a single input channel to a multi-channel output state with the required amplitude and phase profile. For an N-port device, we demonstrate that two layers of N phase shifters can approximate arbitrary N-dimensional amplitude states with sufficient accuracy, while three layers allow complete control over both amplitude and phase. Furthermore, we experimentally demonstrate arbitrary state generation with a silicon photonic platform by utilizing a measurement-and-feedback setting forin situprogramming of the device to optimize the desired output state. The present solution allows for a flexible design, compatible across various material platforms, for the integration of state generators used in future PICs that require arbitrarily complex inputs. 

Mitochondria maintain organellar homeostasis through multiple quality control pathways, including the clearance of defective or unwanted mitochondria by selective autophagy. This removal of mitochondria, mitophagy, is controlled in large part by the outer mitochondrial membrane mitophagy receptors BNIP3 and NIX. While it has long been appreciated that BNIP3 and NIX mediate mitophagy by controlling the recruitment of autophagic machinery to the mitochondrial surface, the requirement for the carefully controlled spatiotemporal regulation of receptor-mediated mitophagy has only recently come to light. Several new factors that regulate the BNIP3/NIX-mediated mitophagy pathway have emerged, and various loss-of-function cell and animal models have revealed the dire consequences of their dysregulation. In this mini-review, we discuss new insights into the mechanisms and roles of the regulation of BNIP3 and NIX and highlight questions that have emerged from the identification of these new regulators. 

Abstract Mitochondrial cristae architecture is crucial for optimal respiratory function of the organelle. Cristae shape is maintained in part by the mitochondrial inner membrane-localized MICOS complex. While MICOS is required for normal cristae morphology, the precise mechanistic role of each of the seven human MICOS subunits, and how the complex coordinates with other cristae shaping factors, has not been fully determined. Here, we examine the MICOS complex inSchizosaccharomyces pombe, a minimal model whose genome only encodes for four core subunits. Using an unbiased proteomics approach, we identify a poorly characterized inner mitochondrial membrane protein that interacts with MICOS and is required to maintain cristae morphology, which we name Mmc1. We demonstrate that Mmc1 works in concert with MICOS complexes to promote normal mitochondrial morphology and respiratory function. Bioinformatic analyses reveal that Mmc1 is a distant relative of the Dynamin-Related Protein (DRP) family of GTPases, which are well established to shape and remodel membranes. We find that, like DRPs, Mmc1 self-associates and forms high molecular weight assemblies. Interestingly, however, Mmc1 is a pseudoenzyme that lacks key residues required for GTP binding and hydrolysis, suggesting it does not dynamically remodel membranes. These data are consistent with a model in which Mmc1 stabilizes cristae architecture by acting as a scaffold to support cristae ultrastructure on the matrix side of the inner membrane. Our study reveals a new class of proteins that evolved early in fungal phylogeny and is required for the maintenance of cristae architecture. This highlights the possibility that functionally analogous proteins work with MICOS to establish cristae morphology in metazoans. 

Dryland riparian woodlands are considered to be locally buffered from droughts by shallow and stable groundwater levels. However, climate change is causing more frequent and severe drought events, accompanied by warmer temperatures, collectively threatening the persistence of these groundwater dependent ecosystems through a combination of increasing evaporative demand and decreasing groundwater supply. We conducted a dendro-isotopic analysis of radial growth and seasonal (semi-annual) carbon isotope discrimination (Δ13C) to investigate the response of riparian cottonwood stands to the unprecedented California-wide drought from 2012 to 2019, along the largest remaining free-flowing river in Southern California. Our goals were to identify principal drivers and indicators of drought stress for dryland riparian woodlands, determine their thresholds of tolerance to hydroclimatic stressors, and ultimately assess their vulnerability to climate change. Riparian trees were highly responsive to drought conditions along the river, exhibiting suppressed growth and strong stomatal closure (inferred from reduced Δ13C) during peak drought years. However, patterns of radial growth and Δ13C were quite variable among sites that differed in climatic conditions and rate of groundwater decline. We show that the rate of groundwater decline, as opposed to climate factors, was the primary driver of site differences in drought stress, and trees showed greater sensitivity to temperature at sites subjected to faster groundwater decline. Across sites, higher correlation between radial growth and Δ13C for individual trees, and higher inter-correlation of Δ13C among trees were indicative of greater drought stress. Trees showed a threshold of tolerance to groundwater decline at 0.5 m year−1 beyond which drought stress became increasingly evident and severe. For sites that exceeded this threshold, peak physiological stress occurred when total groundwater recession exceeded 3 m. These findings indicate that drought-induced groundwater decline associated with more extreme droughts is a primary threat to dryland riparian woodlands and increases their susceptibility to projected warmer temperatures. 

Abstract. Using 11-year-long K Doppler lidar observations of temperatureprofiles in the mesosphere and lower thermosphere (MLT) between 85 and100 km, conducted at the Arecibo Observatory, Puerto Rico(18.35^∘ N, 66.75^∘ W), seasonalvariations of mean temperature, the squared Brunt–Väisäläfrequency, N², and the gravity wave potential energy (GWPE) are estimated in a compositeyear. The following unique features are obtained. (1) The mean temperaturestructure shows similar characteristics to an earlier report based on a smallerdataset. (2) Temperature inversion layers (TILs) occur at 94–96 km inspring, at ∼92 km in summer, and at ∼91 km in early autumn.(3) The first complete range-resolved climatology of GWPE derived from temperature data in the tropical MLT exhibits analtitude-dependent combination of annual oscillation (AO) and semiannualoscillation (SAO). The maximum occurs in spring and the minimum in summer, and asecond maximum is in autumn and a second minimum in winter. (4) The GWPE perunit volume reduces below ∼97 km altitude in all seasons. Thereduction of GWPE is significant at and below the TILs but becomes faintabove; this provides strong support for the mechanism that the formation ofupper mesospheric TILs is mainly due to the reduction of GWPE. The climatologyof GWPE shows an indeed pronounced altitudinal and temporal correlation withthe wind field in the tropical mesopause region published in the literature.This suggests the GW activity in the tropical mesopause region should bemanifested mainly by the filtering effect of the critical level of the localbackground wind and the energy conversion due to local dynamical instability. 

A viable qubit must have a long coherence time T 2 . In molecular nanomagnets, T 2 is often limited at low temperatures by the presence of dipole and hyperfine interactions, which are often mitigated through sample dilution, chemical engineering and isotope substitution in synthesis. Atomic-clock transitions offer another route to reducing decoherence from environmental fields by reducing the effective susceptibility of the working transition to field fluctuations. The Cr7Mn molecular nanomagnet, a heterometallic ring, features a clock transition at zero field. Both continuous-wave and spin-echo electron-spin resonance experiments on Cr7Mn samples, diluted via co-crystallization, show evidence of the effects of the clock transition with a maximum T 2 ∼ 390 ns at 1.8 K. We discuss improvements to the experiment that may increase T 2 further. 

Across the Upper Missouri River Basin, the recent drought of 2000 to 2010, known as the “turn-of-the-century drought,” was likely more severe than any in the instrumental record including the Dust Bowl drought. However, until now, adequate proxy records needed to better understand this event with regard to long-term variability have been lacking. Here we examine 1,200 y of streamflow from a network of 17 new tree-ring–based reconstructions for gages across the upper Missouri basin and an independent reconstruction of warm-season regional temperature in order to place the recent drought in a long-term climate context. We find that temperature has increasingly influenced the severity of drought events by decreasing runoff efficiency in the basin since the late 20th century (1980s) onward. The occurrence of extreme heat, higher evapotranspiration, and associated low-flow conditions across the basin has increased substantially over the 20th and 21st centuries, and recent warming aligns with increasing drought severities that rival or exceed any estimated over the last 12 centuries. Future warming is anticipated to cause increasingly severe droughts by enhancing water deficits that could prove challenging for water management.