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When experimentally learning the action of a continuous-variable quantum process by probing it with inputs, there will often be some restriction on the input states used. One experimentally simple way to probe a quantum channel is to use low-energy coherent states. Learning a quantum channel in this way presents difficulties, due to the fact that two channels may act similarly on low-energy inputs but very differently for high-energy inputs. They may also act similarly on coherent-state inputs but differently on nonclassical inputs. Extrapolating the behavior of a channel for more general input states from its action on the far more limited set of low-energy coherent states is a case of out-of-distribution generalization. To be sure that such generalization gives meaningful results, one needs to relate error bounds for the training set to bounds that are valid for all inputs. We show that for any pair of channels that act sufficiently similarly on low-energy coherent-state inputs, one can bound how different the input-output relations are for any (high-energy or highly nonclassical) input. This proves that out-of-distribution generalization is always possible for learning quantum channels using low-energy coherent states, as long as enough samples are used. 

To achieve more accurate Earth system model projections of diverse climate scenarios, researchers need observation-based data on the movement of carbon between reservoirs, and especially across tropical regions. The Tropical Low-Pressure Belt (TLPB) is a key driver of atmospheric circulation across lower latitudes. While the TLPB shifts across the east–west extent of northern Africa, the extent to which 14C concentrations apply to Afrotropical forests remains untested, restricting our understanding about other carbon feedbacks. Here, we present a high-precision atmospheric 14C record (1940–2012) from a lowland tropical tree species (Entandrophragma utile) in Cameroon. We included 107 measurements from whole rings and 15 intra-annual slices. The intra-annual 14C data from 1962, 1963, and 1964 confirm a 7-month long growing season (April–November) with a photosynthetic profile typical of Northern Hemisphere (NH) sites, and showing no nonstructural-carbohydrate interference. The full 14C record reveals that air masses reaching the site were derived primarily from Southern Hemisphere (SH) readings followed by recycled bomb-14C signals from soil and litter. Radiocarbon results were substantiated by HYSPLIT model trajectories coupled with NCEP/NCAR reanalysis data. The paradox of finding that tropical NH trees grow using 14CO2 of SH air masses and land-surface respiration challenges existing zonal 14C classifications. Our findings highlight an essential role for robust observational 14C data in refining atmospheric models and improving carbon-cycle assessments across distinct climate zones. 

Methane seeps harbor uncharacterized animal–microbe symbioses with unique nutritional strategies. Three undescribed sea spider species (family Ammotheidae; genus Sericosura) endemic to methane seeps were found along the eastern Pacific margin, from California to Alaska, hosting diverse methane-and methanol-oxidizing bacteria on their exoskeleton. δ13C tissue isotope values of in situ specimens corroborated methane assimilation (−45‰, on average). Live animal incubations with 13C-labeled methane and methanol, followed by nanoscale secondary ion mass spectrometry, confirmed that carbon derived from both compounds was actively incorporated into the tissues within five days. Methano-and methylotrophs of the bacterial families Methylomonadaceae, Methylophagaceae and Methylophilaceae were abundant, based on environmental metagenomics and 16S rRNA sequencing, and fluorescence and electron microscopy confirmed dense epibiont aggregations on the sea spider exoskeleton. Egg sacs carried by the males hosted identical microbes suggesting vertical transmission. We propose that these sea spiders farm and feed on methanotrophic and methylotrophic bacteria, expanding the realm of animals known to harness C1 compounds as a carbon source. These findings advance our understanding of the biology of an understudied animal lineage, unlocking some of the unique nutritional links between the microbial and faunal food webs in the oceans. 

To achieve more accurate Earth system model projections of diverse climate scenarios, researchers need observation-based data on the movement of carbon between reservoirs, and especially across tropical regions. The Tropical Low-Pressure Belt (TLPB) is a key driver of atmospheric circulation across lower latitudes. While the TLPB shifts across the east–west extent of northern Africa, the extent to which 14C concentrations apply to Afrotropical forests remains untested, restricting our understanding about other carbon feedbacks. Here, we present a high-precision atmospheric 14C record (1940–2012) from a lowland tropical tree species (Entandrophragma utile) in Cameroon. We included 107 measurements from whole rings and 15 intra-annual slices. The intra-annual 14C data from 1962, 1963, and 1964 confirm a 7-month long growing season (April–November) with a photosynthetic profile typical of Northern Hemisphere (NH) sites, and showing no nonstructural-carbohydrate interference. The full 14C record reveals that air masses reaching the site were derived primarily from Southern Hemisphere (SH) readings followed by recycled bomb-14C signals from soil and litter. Radiocarbon results were substantiated by HYSPLIT model trajectories coupled with NCEP/NCAR reanalysis data. The paradox of finding that tropical NH trees grow using 14CO2 of SH air masses and land-surface respiration challenges existing zonal 14C classifications. Our findings highlight an essential role for robust observational 14C data in refining atmospheric models and improving carbon-cycle assessments across distinct climate zones. 

Methane seeps harbor uncharacterized animal–microbe symbioses with unique nutritional strategies. Three undescribed sea spider species (family Ammotheidae; genusSericosura) endemic to methane seeps were found along the eastern Pacific margin, from California to Alaska, hosting diverse methane- and methanol-oxidizing bacteria on their exoskeleton. δ¹³C tissue isotope values of in situ specimens corroborated methane assimilation (−45‰, on average). Live animal incubations with¹³C-labeled methane and methanol, followed by nanoscale secondary ion mass spectrometry, confirmed that carbon derived from both compounds was actively incorporated into the tissues within five days. Methano- and methylotrophs of the bacterial families Methylomonadaceae, Methylophagaceae and Methylophilaceae were abundant, based on environmental metagenomics and 16S rRNA sequencing, and fluorescence and electron microscopy confirmed dense epibiont aggregations on the sea spider exoskeleton. Egg sacs carried by the males hosted identical microbes suggesting vertical transmission. We propose that these sea spiders farm and feed on methanotrophic and methylotrophic bacteria, expanding the realm of animals known to harness C1 compounds as a carbon source. These findings advance our understanding of the biology of an understudied animal lineage, unlocking some of the unique nutritional links between the microbial and faunal food webs in the oceans. 

We introduce a model of randomly connected neural populations and study its dynamics by means of the dynamical mean-field theory and simulations. Our analysis uncovers a rich phase diagram, featuring high- and low-dimensional chaotic phases, separated by a crossover region characterized by low values of the maximal Lyapunov exponent and participation ratio dimension, but with high values of the Lyapunov dimension that change significantly across the region. Counterintuitively, chaos can be attenuated by either adding noise to strongly modular connectivity or by introducing modularity into random connectivity. Extending the model to include a multilevel, hierarchical connectivity reveals that a loose balance between activities across levels drives the system towards the edge of chaos. 

Mastigoproctus Pocock, 1894, is the most speciose genus in the thelyphonid subfamily Mastigoproctinae Speijer, 1933, with eighteen described species distributed from the Southern United States to Colombia and Venezuela. Ten of these species occur in Mexico. In the present contribution, Mastigoproctus spinifemoratus, sp. nov., is described based on an adult male and two juveniles from Eastern Nuevo León and Southwestern Tamaulipas, Mexico. It differs from five other species of Mastigoproctus, in which spiniform tubercles are present on the retrolateral surface of the pedipalp femur, in the ventrally directed epistome of the carapace, and the absence of an accessory spine on the prodorsal margin of the pedipalp trochanter. The new species raises the number of Mastigoproctus species to nineteen and the number in Mexico to eleven.