Visible Signature Research Articles

Hierarchically structured composite with 3D interlocking architecture for multi-band defense

The development of high-performance electromagnetic wave absorbing (EMWA) materials for radar stealth applications poses a persistent challenge, particularly when addressing the demanding requirements of diverse frequency bands in increasingly complex and dynamic environments. Precisely tailoring the microstructure of these materials presents a powerful strategy for achieving multifunctional integration and unlocking new possibilities for practical applications. In this work, we present a novel hierarchically structured composite foam with 3D interlocking architecture, fabricated through a straightforward foaming and calcination process. It features a unique dual three-dimensional continuous phase structure that facilitates the formation of an efficient conductive network, promoting free electron mobility and enhancing polarization loss. The composite demonstrates exceptional EMWA performance, exhibiting a wide effective absorption bandwidth (EAB) of 6.1 GHz and a remarkable absorption intensity of -63.2 dB along with RCS reduction value up to 28.7 dB m2. Furthermore, the composite illustrated strong infrared stealth properties and efficient photothermal conversion abilities. When heated to 56°C, its surface temperature only increased by 4°C in 10 minutes. Under direct sunlight, its surface temperature rose from 21°C to 71°C in just 6 minutes. Lightweight, flexible, and adaptable to diverse environmental conditions, the HCC composite holds significant promise as a multi-spectrum defense material. Its versatility makes it an ideal candidate for integration into a wide range of equipment, clothing, and wearable technologies, offering advanced capabilities for radar, infrared, and visible light signature reduction.

Major merger fraction along the massive galaxy-quenching channel at 0.2 < z < 0.7

Abstract We study the major merger fraction along the massive galaxy-quenching channel (traced with rest-frame $\mathrm{NUV}-r$ color) at z = 0.2–0.7, aiming to examine the cosmic web detachment (CWD) scenario of galaxy quenching. In this scenario, the major merger fraction is expected to be high in green-valley galaxies as compared with those in star-forming and quiescent galaxies of similar stellar mass. We used photometry in the E-COSMOS field to select 1491 (2334) massive ($M_\ast \\gt 10^{9.5}\, M_{\odot }$) galaxies with $m_i\\lt 22$ mag ($m_z\\lt 22$ mag) at z = 0.2–0.4 (z = 0.4–0.7) in the rest-frame color range of $0.8\\lt r-K_{\rm s}\\lt 1.3$. We define a major galaxy–galaxy merger as a galaxy pair of comparable angular size and luminosity with tidal tails or bridges, and we identified such major mergers through visual inspection of Subaru HSC-SSP PDR 2 i- and z-band images. We classify 92 (123) galaxies as major merger galaxies at z = 0.2–0.4 (z = 0.4–0.7). The resulting major merger fraction is 5%–6% and this fraction does not change with galaxy color along the massive galaxy-quenching channel. The result is not consistent with the expectation based of the CWD scenario as the dominant mechanism of massive galaxy quenching. However, there are some caveats such as (i) the mergers that cause quenching may lose their visible merger signatures rapidly before they enter the green valley, (ii) our method may not trace the cosmic web sufficiently well, and (iii) because of our mass limit, most of the galaxies in our sample may have already experienced CWD events at higher redshifts than those studied here. Further studies with deeper data are desirable in the future.

Dark showers from Z-dark Z′ mixing

We discuss dark shower signals at the LHC from a dark QCD sector, containing GeV-scale dark pions. The portal with the Standard Model is given by the mixing of the Z boson with a dark Z′ coupled to the dark quarks. Both mass and kinetic mixings are included, but the mass mixing is the essential ingredient, as it is the one mediating visible decays of the long-lived dark pions. We focus especially on the possibility that the dark Z′ is lighter than the Z. Indirect constraints are dominated by electroweak precision tests, which we thoroughly discuss, showing that both Z-pole and low-energy observables are important. We then recast CMS and LHCb searches for displaced dimuon resonances to dark shower signals initiated by the production of on-shell Z or Z′, where the visible signature is left by a dark pion decaying to μ+μ−. We demonstrate how dark shower topologies have already tested new parameter space in Run 2, reaching better sensitivity on a light dark Z′ compared to the flavor-changing decays of B mesons, which can produce a single dark pion at a time, and the electroweak precision tests.

An agrogeophysical modelling framework for the detection of soil compaction spatial variability due to grazing using field‐scale electromagnetic induction data

AbstractSoil compaction is a regarded as a major environmental and economical hazard, degrading soils across the world. Changes in soil properties due to compaction are known to lead to decrease in biomass and increase in greenhouse gas emissions, nutrient leaching and soil erosion. Quantifying adverse impacts of soil compaction and developing strategies for amelioration relies on an understanding of soil compaction extent and temporal variability. The main indicators of soil compaction (i.e., reduction of pore space, increase in bulk density and decrease in soil transport properties) are relatively easy to quantify in laboratory conditions but such traditional point‐based methods offer little information on soil compaction extent at the field scale. Recently, geophysical methods have been proposed to provide non‐invasive information about soil compaction. In this work, we developed an agrogeophysical modelling framework to help address the challenges of characterizing soil compaction across grazing paddocks using electromagnetic induction (EMI) data. By integrative modelling of grazing, soil compaction, soil processes and EMI resistivity anomalies, we demonstrate how spatial patterns of EMI observations can be linked to management leading to soil compaction and concurrent modifications of soil functions. The model was tested in a dairy farm in the midlands of Ireland that has been grazed for decades and shows clear signatures of grazing‐induced compaction. EMI data were collected in the summer of 2021 and autumn of 2022 under dry and wet soil moisture conditions, respectively. For both years, we observed decreases of apparent electrical resistivity at locations that with visible signatures of compaction such as decreased vegetation and water ponding (e.g., near the water troughs and gates). A machine learning algorithm was used to cluster EMI data with three unique cluster signatures assumed to be representative of heavy, moderately, and non‐compacted field zones. We conducted 1D process‐based simulations corresponding to non‐compacted and compacted soils. The modelled EMI signatures agree qualitatively and quantitatively with the measured EMI data, linking decreased electrical resistivities to zones that were visibly compacted. By providing a theoretical framework based on mechanistic modelling of soil management and compaction, our work may provide a strategy for utilizing EMI data for detection of soil degradation due to compaction.

Bridge-induced taming of the visible electronic circular dichroism signatures of helicoBODIPYs

Helically-flexible bis(BODIPY)s based on chiral ethane-1,2-diamine or −1,2-diol bridges (named helicoBODIPYs) are an interesting family of accessible and tunable small multichromophoric organic dyes enabling visible electronic circular dichroism (ECD) and, even visible circularly polarized luminescence (CPL). However, their CPL brightness (BCPL) is still limited (up to ca. 10 M−1cm−1), due to low fluorescence efficiency owing to a non-optimal participation of intramolecular charge transfer (CT) emission. Herein, we analyze in depth the origin and factors controlling this CT, demonstrating the key participation of a BODIPY-to-BODIPY symmetry-breaking induced CT (SBCT), beyond the expected CT within each single BODIPY chromophore due to their push-pull character. It is also demonstrated that increasing the overcrowding at the flexible helicoBODIPY ethane bridges leads to BODIPY-BODIPY faced dispositions, promoting the SBCT and enabling the detection of both CT absorption and CT emission bands under specific conditions. Interestingly, this SBCT enhances the visible ECD (absolute gabs values), supporting the key role of the involved forbidden CT transitions in the chiroptical activity of these dyes, as well as the possibility of modulating their valuable visible chiroptical signatures (e.g., visible CPL brightness) by easily playing with steric factors at the dye bridge.

Maximizing visible Raman resolution of nanodiamond grains fabricated by coaxial arc plasma deposition through oxygen plasma etching optimization

Among the nondestructive carbon material characterization tools, the prominence of visible Raman spectroscopy has surged remarkably for many years due to its ability to explore a diverse array of carbon bonding configurations. However, to fully unlock the distinctive features concealed within carbon composite materials, additional specimen treatments or precise spectroscope calibrations are necessary. In the same regard, the tiny diamond grain size (5–10 nm) and the pronounced amount of sp2 carbon in the ultrananocrystalline diamond film represent major challenges in visible light excitation. In this work, we employ calibrated oxygen plasma reactive ion etching conditions to manifest the nanodiamond visible Raman signature from ultrananocrystalline diamond/amorphous carbon composite (UNCD/a‐C) films fabricated by coaxial arc plasma deposition. Upon plasma etching, the broad defect band in the visible Raman spectra converged toward the diamond characteristic Raman peak at 1332 cm−1. A detailed explanation of band components of the Raman spectra is extracted through peak fitting procedures. The results of Raman spectroscopy are further correlated with the electrical characteristics of the nitrogen‐doped UNCD/a‐C films due to the optimized oxygen plasma etching processes.

DarkNews: A Python-based event generator for heavy neutral lepton production in neutrino-nucleus scattering

We introduce DarkNews, a lightweight Python -based Monte-Carlo generator for beyond-the-Standard-Model neutrino-nucleus scattering. The generator handles the production and decay of heavy neutral leptons via additional vector or scalar mediators, as well as through transition magnetic moments. DarkNews samples pre-computed neutrino-nucleus upscattering cross sections and heavy neutrino decay rates to produce dilepton and single-photon events in accelerator neutrino experiments. We present two case studies with differential distributions for models that can explain the MiniBooNE excess. The aim of this code is to aid the neutrino theory and experimental communities in performing searches and sensitivity studies for new particles produced in neutrino upscattering. Program summaryProgram Title: DarkNewsCPC Library link to program files:https://doi.org/10.17632/k9nh5fn4pw.1Developer's repository link:https://github.com/mhostert/DarkNews-generatorLicensing provisions: MITProgramming language: PythonNature of problem: In many theories beyond the Standard Model of particle physics, new light particles are introduced with masses below the 100 GeV scale. These can be produced by neutrino-nucleus interactions inside neutrino detectors, leaving a visible signature through their decay. To search for these signatures, experiments have to simulate the underlying physical processes, which requires detailed knowledge of the cross sections and decay rates in the model, as well as the ability to generate Monte Carlo events.Solution method: DarkNews provides the necessary tools to simulate the production of heavy neutral leptons in accelerator neutrino experiments, focusing on neutrino-nucleus scattering processes. The program's scope includes models with new mediators and three heavy neutral leptons, parameterizing a large class of theories through generic neutrino, quark, and lepton interactions. It generates weighted Monte-Carlo events using vegas and its pre-calculated differential rates.

A Comparison of Laboratory and Field Measurements of Whitecap Foam Evolution From Breaking Waves

AbstractSufficiently energetic breaking ocean waves produce distinctive visible foam signatures on the water surface called whitecaps. The mixture of surface whitecap foam cells, and sub‐surface bubbles, results in the broad‐band scattering of light that allow whitecaps to be measured with optical cameras. In this paper the temporal evolution of whitecap foam area from laboratory and oceanic breaking waves is compared. When appropriately scaled, the foam area time series for both laboratory and oceanic breaking waves follow similar trends, despite occurring in vastly different settings. Distinct similarities of the signature of foam stabilization due to the presence of surfactants in the controlled laboratory experiments are also found in the field suggesting foam stabilization may be a means to remotely sense the presence/absence or concentration of surfactants in the ocean. In addition, probability density distributions of key whitecap variables such as foam area growth and decay timescales and maximum foam area are compared between laboratory and oceanic whitecaps. The oceanic whitecaps are much larger in scale than the laboratory breaking waves, whereas the whitecap growth and decay timescales are similar in magnitude, the latter suggesting that the depths to which bubbles are injected during active air entrainment in the field are relatively shallow. The aggregated whitecap statistics are used to estimate the energy dissipation of individual whitecaps in a novel manner.

Minimizing cell number fluctuations in self-renewing tissues with a stem-cell niche.

Self-renewing tissues require that a constant number of proliferating cells is maintained over time. This maintenance can be ensured at the single-cell level or the population level. Maintenance at the population level leads to fluctuations in the number of proliferating cells over time. Often, it is assumed that those fluctuations can be reduced by increasing the number of asymmetric divisions, i.e., divisions where only one of the daughter cells remains proliferative. Here, we study a model of cell proliferation that incorporates a stem-cell niche of fixed size, and explicitly model the cells inside and outside the niche. We find that in this model, fluctuations are minimized when the difference in growth rate between the niche and the rest of the tissue is maximized and all divisions are symmetric divisions, producing either two proliferating or two nonproliferating daughters. We show that this optimal state leaves visible signatures in clone size distributions and could thus be detected experimentally.

Smartwatch In-Air Signature Time Sequence Three-Dimensional Static Restoration Classification Based on Multiple Convolutional Neural Networks

In-air signatures are promising applications that have been investigated extensively in the past decades; an in-air signature involves gathering datasets through portable devices, such as smartwatches. During the signing process, individuals wear smartwatches on their wrists and sign their names in the air. The dataset we used in this study collected in-air signatures from 22 participants, resulting in a total of 440 smartwatch in-air signature signals. The dynamic time warping (DTW) algorithm was applied to verify the usability of the dataset. This paper analyzes and compares the performances of multiple convolutional neural networks (CNN) and the transformer using median-sized smartwatch in-air signatures. For the four CNN models, the in-air digital signature data were first transformed into visible three-dimensional static signatures. For the transformer, the nine-dimensional in-air signature signals were concatenated and downsampled to the desired length and then fed into the transformer for time sequence signal multi-classification. The performance of each model on the smartwatch in-air signature dataset was thoroughly tested with respect to 10 optimizers and different learning rates. The best testing performance score in our experiment was 99.8514% with ResNet by using the Adagrad optimizer under a 1×10−4 learning rate.

(In)Visible signatures of the minimal dark abelian gauge sector

In this paper we study the present and future sensitivities of the rare meson decay facilities KOTO, LHCb and Belle II to a light dark sector of the minimal dark abelian gauge symmetry where a dark Higgs S and a dark photon ZD have masses ≲ 10 GeV. We have explored the interesting scenario where S can only decay to a pair of ZD’s and so contribute to visible or invisible signatures, depending on the life-time of the latter. Our computations show that these accelerator experiments can access the dark Higgs (mass and scalar mixing) and the dark photon (mass and kinetic mixing) parameters in a complementary way. We have also discussed how the CMS measurement of the SM Higgs total decay width and their limit on the Higgs invisible branching ratio can be used to extend the experimental reach to dark photon masses up to ~ 10 GeV, providing at the same time sensitivity to the gauge coupling associated with the broken dark abelian symmetry.

An Ionospheric Conductance Gradient Driver for Subauroral Picket Fence Visible Signatures Near STEVE Events

AbstractReported observations of picket fence signatures associated with subauroral Strong Thermal Emission Velocity Enhancement (STEVE) emission events look strikingly similar to rayed auroral curtains. Rayed auroral curtains are often the visible signatures of tearing‐mode‐unstable current sheets with precipitating auroral electron current carriers. Picket fence signatures are not located where auroral precipitation explanations apply, and are closely collocated with STEVE emission events. A similar tearing‐mode‐instability explanation can be invoked with a different source for the originating field‐aligned current (FAC) sheet. In this explanation, the FAC sheet is sourced by ionospheric conductance gradients adjacent to the localized flows of the STEVE event. Geospace Environment Model of Ion‐Neutral Interactions (GEMINI) models of the 3D ionosphere near counterstreaming STEVE‐associated flow structures show the development of sufficiently strong current sheets for tearing mode instabilities to take hold. These instabilities can locally accelerate ambient ionospheric thermal electrons to the few eV needed for the reported observed green picket fence signatures.

Hermitian K-theory for stable infty -categories I: Foundations

This paper is the first in a series in which we offer a new framework for hermitian {text {K}}-theory in the realm of stable infty -categories. Our perspective yields solutions to a variety of classical problems involving Grothendieck-Witt groups of rings and clarifies the behaviour of these invariants when 2 is not invertible. In the present article we lay the foundations of our approach by considering Lurie’s notion of a Poincaré infty -category, which permits an abstract counterpart of unimodular forms called Poincaré objects. We analyse the special cases of hyperbolic and metabolic Poincaré objects, and establish a version of Ranicki’s algebraic Thom construction. For derived infty -categories of rings, we classify all Poincaré structures and study in detail the process of deriving them from classical input, thereby locating the usual setting of forms over rings within our framework. We also develop the example of visible Poincaré structures on infty -categories of parametrised spectra, recovering the visible signature of a Poincaré duality space. We conduct a thorough investigation of the global structural properties of Poincaré infty -categories, showing in particular that they form a bicomplete, closed symmetric monoidal infty -category. We also study the process of tensoring and cotensoring a Poincaré infty -category over a finite simplicial complex, a construction featuring prominently in the definition of the {text {L}}- and Grothendieck-Witt spectra that we consider in the next instalment. Finally, we define already here the 0th Grothendieck-Witt group of a Poincaré infty -category using generators and relations. We extract its basic properties, relating it in particular to the 0th {text {L}}- and algebraic {text {K}}-groups, a relation upgraded in the second instalment to a fibre sequence of spectra which plays a key role in our applications.

Comparative evaluation and selection of submarines with air-independent propulsion system

Conventional submarines produced to date can be more easily detected and exposed to attacks due to their visible, infrared, and radar signatures. Diesel-electric submarines need to come to a close surface at certain time intervals to charge their batteries and power their diesel generators with snorting systems. This situation causes submarines to face threats from land, sea, and air war elements. In order to reduce these threats, it is clear that there is a need for an innovative system in which the need for submarines to the surface is minimized and the timing of emergence is more flexible. To ensure this situation, air-independent propulsion systems have come to the fore from past to present and have gained more and more strategic importance. These air-independent systems significantly improve silent underwater time, and maneuverability and greatly contribute to maintaining the submarine's military stealth strategy. In this context, in this study, six different power system alternatives used as air-independent propulsion (AIP) submarine systems were evaluated, their advantages and disadvantages were compared, and alternatives were sorted by five experts in terms of nine important technical and economic criteria with the fuzzy VIKOR method. It has been seen that the propulsion power with the fuel cell system comes to the fore. The choice of a high power density fuel cell system for a submarine AIP system can allow for superior underwater range and durability and a minimal rate of instability and thermal signature than would be achievable from any heat engine. This will greatly expand the strategic advantage of AIP submarines. In this respect, this article can be a guide in understanding the critical technical features of submarines and in deciding between alternatives in submarine system selection.

UV-visible chemiluminescence signature of laminar ammonia-hydrogen-air flames

This work investigates the UV and visible chemiluminescence signatures of laminar ammonia-hydrogen-air flames. A counterflow burner was used to stabilize flat and steady premixed ammonia-hydrogen-air twin-flames for wide ranges of ammonia fuel fractions (0.55≤XNH3≤0.90), equivalence ratios (0.35≤ϕ≤1.70), and strain rates (50≤a≤300/s). The chemiluminescence spectra in the UV and visible regions were measured. The important contributors to the chemiluminescence of ammonia-hydrogen-air flames were first identified and their sensitivities to equivalence ratio and ammonia fuel fraction were then quantified. Promising ratios of chemiluminescence intensities for the non-intrusive optical sensing of equivalence ratio and ammonia fuel fraction in premixed ammonia-hydrogen-air flames were also identified. Among the 36 ratios that could be formed with the 9 contributors to chemiluminescence that were defined, 3 are particularly promising, namely, OH*/NO*, OH*/violet (violet refers to the 350 to 400 nm range), and red/blue (blue and red refer to the 450 to 500 nm and 650 to 750 nm ranges, respectively). Ratios OH*/NO* and OH*/violet were found to provide suitable measures of equivalence ratio for lean and rich ammonia-hydrogen-air flames, respectively, because these ratios are very sensitive to equivalence ratio, are insensitive to ammonia fuel fraction, and are marginally sensitive to strain rate. Once equivalence ratio is known, the ammonia fuel fraction can then be measured with ratio red/blue because it is sensitive to the ammonia fuel fraction and it is globally insensitive to strain rate.

Towards the Identification and Classification of Solar Granulation Structures Using Semantic Segmentation

Solar granulation is the visible signature of convective cells at the solar surface. The granulation cellular pattern observed in the continuum intensity images is characterised by diverse structures e.g., bright individual granules of hot rising gas or dark intergranular lanes. Recently, the access to new instrumentation capabilities has given us the possibility to obtain high-resolution images, which have revealed the overwhelming complexity of granulation (e.g., exploding granules and granular lanes). In that sense, any research focused on understanding solar small-scale phenomena on the solar surface is sustained on the effective identification and localization of the different resolved structures. In this work, we present the initial results of a proposed classification model of solar granulation structures based on neural semantic segmentation. We inspect the ability of the U-net architecture, a convolutional neural network initially proposed for biomedical image segmentation, to be applied to the dense segmentation of solar granulation. We use continuum intensity maps of the IMaX instrument onboard the Sunrise I balloon-borne solar observatory and their corresponding segmented maps as a training set. The training data have been labeled using the multiple-level technique (MLT) and also by hand. We performed several tests of the performance and precision of this approach in order to evaluate the versatility of the U-net architecture. We found an appealing potential of the U-net architecture to identify cellular patterns in solar granulation images reaching an average accuracy above 80% in the initial training experiments.

Thermal transport in two-dimensional nematic superconductors

We study the thermal transport in a two-dimensional system with coexisting superconducting (SC) and nematic orders. We analyze the nature of the coexistence phase in a tight-binding square lattice where the nematic state is modelled as a $d$-wave Pomeranchuk-type instability and the feedback of the symmetry breaking nematic state on the SC order is accounted for by mixing of the $s, d$ paring interaction. The electronic thermal conductivity is computed within the framework of Boltzmann kinetic theory where the impurity scattering collision integral is treated in the Born and unitary limits. We present qualitative, analytical, and numerical results that show that the heat transport properties of SC states emerging from a nematic background are quite distinct and depend on the degree of anisotropy of the SC gap induced by nematicity. We describe the influence of the Fermi surface topology, the van Hove singularities, and the presence or absence of zero-energy excitations in the coexistence phase on the the low-temperature behavior of the thermal conductivity. Our main conclusion is that the interplay of nematic and SC orders has visible signatures in the thermal transport, which can be used to infer SC gap structure in the coexistence phase.

B modes from postinflationary gravitational waves sourced by axionic instabilities at cosmic reionization

We show that axion-like particles that only couple to invisible dark photons can generate visible B-mode signals around the reionization epoch. The axion field starts rolling shortly before reionization, resulting in a tachyonic instability for the dark photons. This generates an exponential growth of the dark photon quanta sourcing both scalar metric modes and gravitational waves that leave an imprint on the reionized baryons. The tensor modes modify the cosmic microwave background (CMB) polarization at reionization, generating visible B-mode signatures for the next generation of CMB experiments for parameter ranges that satisfy the current experimental constraints.

Remote Sensing Reveals Lasting Legacies of Land-Use by Small-Scale Foraging Communities in the Southwestern Indian Ocean

Archaeologists interested in the evolution of anthropogenic landscapes have productively adopted Niche Construction Theory (NCT), in order to assess long-term legacies of human-environment interactions. Applications of NCT have especially been used to elucidate co-evolutionary dynamics in agricultural and pastoral systems. Meanwhile, foraging and/or highly mobile small-scale communities, often thought of as less intensive in terms of land-use than agropastoral economies, have received less theoretical and analytical attention from a landscape perspective. Here we address this lacuna by contributing a novel remote sensing approach for investigating legacies of human-environment interaction on landscapes that have a long history of co-evolution with highly mobile foraging communities. Our study is centered on coastal southwest Madagascar, a region inhabited by foraging and fishing communities for close to two millennia. Despite significant environmental changes in southwest Madagascar’s environment following human settlement, including a wave of faunal extinctions, little is known about the scale, pace and nature of anthropogenic landscape modification. Archaeological deposits in this area generally bear ephemeral traces of past human activity and do not exhibit readily visible signatures of intensive land-use and landscape modification (e.g., agricultural modifications, monumental architecture, etc.). In this paper we use high-resolution satellite imagery and vegetative indices to reveal a legacy of human-landscape co-evolution by comparing the characteristics – vegetative productivity and geochemical properties – of archaeological sites to those of locations with no documented archaeological materials. Then, we use a random forest (RF) algorithm and spatial statistics to quantify the extent of archaeological activity and use this analysis to contextualize modern-day human-environment dynamics. Our results demonstrate that coastal foraging communities in southwest Madagascar over the past 1,000 years have extensively altered the landscape. Our study thus expands the temporal and spatial scales at which we can evaluate human-environment dynamics on Madagascar, providing new opportunities to study early periods of the island’s human history when mobile foraging communities were the dominant drivers of landscape change.

Characterization of primary and aged wood burning and coal combustion organic aerosols in an environmental chamber and its implications for atmospheric aerosols

Abstract. Particulate matter (PM) affects visibility, climate, and public health. Organic matter (OM), a uniquely complex portion of PM, can make up more than half of total atmospheric fine PM mass. We investigated the effect of aging on secondary organic aerosol (SOA) concentration and composition for wood burning (WB) and coal combustion (CC) emissions, two major atmospheric OM sources, using mid-infrared (MIR) spectroscopy and aerosol mass spectrometry (AMS). For this purpose, primary emissions were injected into an environmental chamber and aged using hydroxyl (diurnal aging) and nitrate (nocturnal aging) radicals to reach an atmospherically relevant oxidative age. A time-of-flight AMS instrument was used to measure the high-time-resolution composition of non-refractory fine PM, while fine PM was collected on PTFE filters before and after aging for MIR analysis. AMS and MIR spectroscopy indicate an approximately 3-fold enhancement of organic aerosol (OA) concentration after aging (not wall-loss corrected). The OM:OC ratios also agree closely between the two methods and increase, on average, from 1.6 before aging to 2 during the course of aging. MIR spectroscopy, which is able to differentiate among oxygenated groups, shows a distinct functional group composition for aged WB (high abundance of carboxylic acids) and CC OA (high abundance of non-acid carbonyls) and detects aromatics and polycyclic aromatic hydrocarbons (PAHs) in emissions of both sources. The MIR spectra of fresh WB and CC aerosols are reminiscent of their parent compounds with differences in specific oxygenated functional groups after aging, consistent with expected oxidation pathways for volatile organic compounds (VOCs) of each emission source. The AMS mass spectra also show variations due to source and aging that are consistent with the MIR functional group (FG) analysis. Finally, a comparison of the MIR spectra of aged chamber WB OA with that of ambient samples affected by residential wood burning and wildfires reveals similarities regarding the high abundance of organics, especially acids, and the visible signatures of lignin and levoglucosan. This finding is beneficial for the source identification of atmospheric aerosols and interpretation of their complex MIR spectra.