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1. Photonic Interference Beyond Two Modes

   https://doi.org/10.1364/QUANTUM.2023.QW4A.3  

   Oliver, Richard; Blau, Miri; Ji, Xingchen; Gutiérrez-Jáuregui, Ricardo; Asenjo-Garcia, Ana; Lipson, Michal; Gaeta, Alexander L (June 2023, Optica Quantum 2.0 Conference and Exhibition)

   We propose multipartite Bragg-scattering to perform all-to-all transformation among N frequency modes, realizing a bosonic N-level system. We demonstrate the N = 3 case illustrating a pathway towards scalability for frequency-domain optical quantum information systems. 

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2. Century-scale wood nitrogen isotope trajectories from an oak savanna with variable fire frequencies

   https://doi.org/10.5194/bg-17-4509-2020  

   Trumper, Matthew L.; Griffin, Daniel; Hobbie, Sarah E.; Howard, Ian M.; Nelson, David M.; Reich, Peter B.; McLauchlan, Kendra K. (January 2020, Biogeosciences)

   Abstract. Fire frequency exerts a fundamental control on productivity and nutrientcycling in savanna ecosystems. Individual fires often increaseshort-term nitrogen (N) availability to plants, but repeated burningcauses ecosystem N losses and can ultimately decrease soil organicmatter and N availability. However, these effects remain poorlyunderstood due to limited long-term biogeochemical data. Here, weevaluate how fire frequency and changing vegetation compositioninfluenced wood stable N isotopes (δ15N) across space andtime at one of the longest running prescribed burn experimentsin the world (established in 1964). We developed multiple δ15N recordsacross a burn frequency gradient from precisely dated Quercus macrocarpa tree rings in an oak savanna at Cedar Creek EcosystemScience Reserve, Minnesota, USA. Sixteen trees were sampled across fourtreatment stands that varied with respect to the temporal onset of burning and burnfrequency but were consistent in overstory species representation, soilcharacteristics, and topography. Burn frequency ranged from an unburnedcontrol stand to a high-fire-frequency stand that had burned in 4 ofevery 5 years during the past 55 years. Because N stocks and net Nmineralization rates are currently lowest in frequently burned stands,we hypothesized that wood δ15N trajectories would declinethrough time in all burned stands, but at a rate proportional to the firefrequency. We found that wood δ15N records within each standwere remarkably coherent in their mean state and trend through time. Agradual decline in wood δ15N occurred in the mid-20thcentury in the no-, low-, and medium-fire stands, whereas there was notrend in the high-fire stand. The decline in the three stands did notsystematically coincide with the onset of prescribed burning. Thus, wefound limited evidence for variation in wood δ15N that couldbe attributed directly to long-term fire frequency in this prescribedburn experiment in temperate oak savanna. Our wood δ15Nresults may instead reflect decadal-scale changes in vegetationcomposition and abundance due to early- to mid-20th-century firesuppression. 

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3. Agile frequency transformations for dense wavelength-multiplexed communications

   https://doi.org/10.1364/OE.396142  

   Lu, Hsuan-Hao; Qi, Bing; Williams, Brian_P; Lougovski, Pavel; Weiner, Andrew_M; Lukens, Joseph_M (June 2020, Optics Express)

   The broad bandwidth and spectral efficiency of photonics has facilitated unparalleled speeds in long-distance lightwave communication. Yet efficient routing and control of photonic information without optical-to-electrical conversion remains an ongoing research challenge. Here, we demonstrate a practical approach for dynamically transforming the carrier frequencies of dense wavelength-division–multiplexed data. Combining phase modulators and pulse shapers into an all-optical frequency processor, we realize both cyclic channel hopping and 1-to-Nbroadcasting of input data streams for systems withN = 2 andN = 3 users. Our method involves no optical-to-electrical conversion and enables low-noise, reconfigurable routing of fiber-optic signals with in principle arbitrary wavelength operations in a single platform, offering new potential for low-latency all-optical networking. 

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4. Soil disturbance cover data on 1m x 1m plots from the long-term Small Mammal Exclusion Study (SMES) at Jornada Basin LTER, 1995-2020

   https://doi.org/10.6073/pasta/b722388d1043e99ff0d0a7c6463e60ce  

   Lightfoot, David C; Bestelmeyer, Brandon T (January 2022, Environmental Data Initiative)

   This data package contains soil disturbance data from plots with various levels of herbivore exclusion on the Jornada Experimental Range. Study sites were established in 1995; one in black grama grassland and the other in creosotebush shrubland to compare the impact of herbivores on ecosystem processes between these vegetation types. Parallel studies were established at the Sevilleta LTER site (New Mexico, USA) and Mapimi Biosphere Reserve (Durango, Mexico). Each study site is 1 km by 0.5 km in area. Four replicate experimental blocks were randomly located at the grassland study site to measure vegetation responses using exclusion treatments including a) all mammalian herbivores, including cattle, lagomorphs, and rodents, b) lagomorphs and cattle only, c) cattle only, and d) control accessible to all herbivores. Because grazing cattle are excluded from the entire creosote site, only three replicate experimental blocks were randomly located there including a) all mammalian herbivores, including lagomorphs, and rodents, b) lagomorphs only, and c) control accessible to all herbivores. Thirty-six sampling points were positioned at 5.8-meter intervals on a systematically located 6 by 6 point grid within each plot. A permanent one-meter by one-meter vegetation measurement quadrat is located at each of the 36 points. Each year in spring and fall from 1995-2005, various forms of disturbances (human, rabbit, cow, antelope, rodent, etc) were measured by depth . After 2005, sampling frequency changed to every 5 years. This study is ongoing. 

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5. Rabbit feces counts on 1m x 1m plots from the long-term Small Mammal Exclosure Study (SMES) at Jornada Basin LTER, 1995-2020

   https://doi.org/10.6073/pasta/fd67f23358c01e5770b51597d89f0452  

   Lightfoot, David C; Bestelmeyer, Brandon T (January 2022, Environmental Data Initiative)

   This data package contains rabbit feces count data from plots with various levels of herbivore exclusion on Jornada Experimental Range (JER) and Chihuahuan Desert Rangeland Research Center (CDRRC) lands. Study sites were established in 1995; one in black grama grassland and the other in creosotebush shrubland to compare the impact of herbivores on ecosystem processes between these vegetation types. Parallel studies were established at the Sevilleta LTER site (New Mexico, USA) and Mapimi Biosphere Reserve (Durango, Mexico). Each study site is 1 km by 0.5 km in area. Four replicate experimental blocks were randomly located at the grassland study site to measure vegetation responses using exclusion treatments including a) all mammalian herbivores, including cattle, lagomorphs, and rodents, b) lagomorphs and cattle only, c) cattle only, and d) control accessible to all herbivores. Because grazing cattle are excluded from the entire creosote site, only three replicate experimental blocks were randomly located there including a) all mammalian herbivores, including lagomorphs, and rodents, b) lagomorphs only, and c) control accessible to all herbivores. Thirty-six sampling points were positioned at 5.8-meter intervals on a systematically located 6 by 6 point grid within each plot. A permanent one-meter by one-meter vegetation measurement quadrat is located at each of the 36 points. Each year in spring and fall from 1995-2005, the total number of rabbit feces were counted within each quadrat. After 2005, sampling frequency channged to every 5 years and data collected record only presence or absence of feces. This study is ongoing. 

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