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We describe the spectrophotometric calibration of the Mid-Infrared Instrument's (MIRI) Medium Resolution Spectrometer (MRS) aboard the James Webb Space Telescope (JWST). This calibration is complicated by a time-dependent evolution in the effective throughput of the MRS; this evolution is strongest at long wavelengths, approximately a factor of 2 at 25um over the first two years of the mission. We model and correct for this evolution through regular observations of internal calibration lamps. Pixel flatfields are constructed from observations of the infrared-bright planetary nebula NGC 7027, and photometric aperture corrections from a combination of theoretical models and observations of bright standard stars. We tie the 5--18um flux calibration to high signal/noise (S/N; ~ 600-1000) observations of the O9 V star 10 Lacertae, scaled to the average calibration factor of nine other spectrophotometric standards. We calibrate the 18--28um spectral range using a combination of observations of main belt asteroid 515 Athalia and the circumstellar disk around young stellar object SAO 206462. The photometric repeatability is stable to better than 1% in the wavelength range 5--18um, and the S/N ratio of the delivered spectra is consistent between bootstrapped measurements, pipeline estimates, and theoretical predictions. The MRS point-source calibration agrees with that of the MIRI imager to within 1% from 7 to 21um and is approximately 1% fainter than prior Spitzer observations, while the extended source calibration agrees well with prior Cassini/CIRS and Voyager/IRIS observations., Comment: 29 pages, 32 figures. Submitted to AJ

The absolute flux calibration of the Mid-Infrared Instrument Imaging and Coronagraphy is based on observations of multiple stars taken during the first 2.5 years of JWST operations. The observations were designed to ensure that the flux calibration is valid for a range of flux densities, different subarrays, and different types of stars. The flux calibration was measured by combining observed aperture photometry corrected to infinite aperture with predictions based on previous observations and models of stellar atmospheres. A subset of these observations were combined with model point-spread-functions to measure the corrections to infinite aperture. Variations in the calibration factor with time, flux density, background level, type of star, subarray, integration time, rate, and well depth were investigated, and the only significant variations were with time and subarray. Observations of the same star taken approximately every month revealed a modest time-dependent response loss seen mainly at the longest wavelengths. This loss is well characterized by a decaying exponential with a time constant of ~200 days. After correcting for the response loss, the band-dependent scatter around the corrected average (aka repeatability) was found to range from 0.1 to 1.2%. Signals in observations taken with different subarrays can be lower by up to 3.4% compared to FULL frame. After correcting for the time and subarray dependencies, the scatter in the calibration factors measured for individual stars ranges from 1 to 4% depending on the band. The formal uncertainties on the flux calibration averaged for all observations are 0.3 to 1.0%, with longer-wavelength bands generally having larger uncertainties., Comment: 26 pages, 17 figures, submitted to AJ

Optically active solid-state spin systems play an important role in quantum technologies. We introduce a new readout scheme, termed Time to Space (T2S) encoding which decouples spin manipulation from optical readout both temporally and spatially. This is achieved by controlling the spin state within a region of interest, followed by rapid scanning of the optical readout position using an acousto-optic modulator. Time tracking allows the optical readout position to be encoded as a function of time. Using nitrogen-vacancy (NV) center ensembles in diamond, we first demonstrate that the T2S scheme enables correlated experiments for efficient common mode noise cancellation in various nano- and microscale sensing scenarios. In the second example, we show highly scalable multi-pixel imaging that does not require a camera and has the potential to accelerate data acquisition by several hundred times compared to conventional scanning methods. We anticipate widespread adoption of this technique, as it requires no additional components beyond those commonly used in optically addressable spin systems.

While magnetic monopoles have extensive theoretical justification for their existence, but have proved elusive to observe, ball lightning is both relatively frequently observed and largely unexplained theoretically. It was first proposed in 1990 that ball lightning might result from the catalysis of nuclear fission by a magnetic monopole. The observed frequency of ball lightning does not conflict with current upper theoretical or observational bounds for magnetic monopole flux. Some possible mechanisms to account for the association of magnetic-monopole-caused ball lightning with thunderstorms are described, and proposals for further observational and theoretical research are made., Comment: 16 pages, 1 figure

We present new JWST observations of the nearby, prototypical edge-on, spiral galaxy NGC 891. The northern half of the disk was observed with NIRCam in its F150W and F277W filters. Absorption is clearly visible in the mid-plane of the F150W image, along with vertical dusty plumes that closely resemble the ones seen in the optical. A $\sim 10 \times 3~{\rm kpc}^2$ area of the lower circumgalactic medium (CGM) was mapped with MIRI F770W at 12 pc scales. Thanks to the sensitivity and resolution of JWST, we detect dust emission out to $\sim 4$ kpc from the disk, in the form of filaments, arcs, and super-bubbles. Some of these filaments can be traced back to regions with recent star formation activity, suggesting that feedback-driven galactic winds play an important role in regulating baryonic cycling. The presence of dust at these altitudes raises questions about the transport mechanisms at play and suggests that small dust grains are able to survive for several tens of million years after having been ejected by galactic winds in the disk-halo interface. We lay out several scenarios that could explain this emission: dust grains may be shielded in the outer layers of cool dense clouds expelled from the galaxy disk, and/or the emission comes from the mixing layers around these cool clumps where material from the hot gas is able to cool down and mix with these cool cloudlets. This first set of data and upcoming spectroscopy will be very helpful to understand the survival of dust grains in energetic environments, and their contribution to recycling baryonic material in the mid-plane of galaxies., Comment: Accepted for publication in Astronomy & Astrophysics; 16 pages, 8 figures

Context. The modeling of stellar spectra of flux standards observed by the Hubble and James Webb space telescopes requires a large synthetic spectral library that covers a wide atmospheric parameter range. Aims. The aim of this paper is to present and describe the calculation methods behind the updated version of the BOSZ synthetic spectral database, which was originally designed to fit the CALSPEC flux standards. These new local thermodynamic equilibrium (LTE) models incorporate both MARCS and ATLAS9 model atmospheres, updated continuous opacities, and 23 new molecular line lists. Methods. The new grid was calculated with Synspec using the LTE approximation and covers metallicities [M/H] from -2.5 to 0.75 dex, [alpha/M] from -0.25 to 0.5 dex, and [C/M] from -0.75 to 0.5 dex, providing spectra for 336 unique compositions. Calculations for stars between 2800 and 8000 K use MARCS model atmospheres, and ATLAS9 is used between 7500 and 16,000 K. Results. The new BOSZ grid includes 628,620 synthetic spectra from 50 nm to 32 microns with models for 495 Teff - log g parameter pairs per composition and per microturbulent velocity. Each spectrum has eight different resolutions spanning a range from R = 500 to 50,000 as well as the original resolution of the synthesis. The microturbulent velocities are 0, 1, 2, and 4 km/s. Conclusions. The new BOSZ grid extends the temperature range to cooler temperatures compared to the original grid because the updated molecular line lists make modeling possible for cooler stars. A publicly available and consistently calculated database of model spectra is important for many astrophysical analyses, for example spectroscopic surveys and the determination of stellar elemental compositions., Comment: 11 pages, 7 figures, 5 tables, published in A&A, new version includes proof corrections

The JWST has been collecting scientific data for over two years now. Scientists are now looking deeper into the data, which introduces the need to correct known systematic effects. Important limiting factors for the MIRI/MRS are the pointing accuracy, non-linearity, detector charge migration, detector scattering, the accuracy of the PSF model, and the complex interplay between these. The Cycle 2 programme 3779 proposed a 72-point intra-pixel dither raster of the calibration star 10-Lac. In this first work of the paper series, we aim to address the degeneracy between the non-linearity and BFE that affect the pixel voltage integration ramps of the MRS. Due to the low flux in the longer wavelengths, we only do this in the 4.9 to 11.7 micron region. We fitted the ramps per pixel and dither, in order to fold in the deviations from classical non-linearity that are caused by charge migration. The ramp shapes should be repeatable depending on the part of the PSF that is sampled. By doing so, we defined both a grid-based linearity correction, and an interpolated linearity correction. We find significant improvements compared to the uniform illumination assumption. The standard deviation on the pixel ramp residual non-linearity is between 70-90% smaller than the current standard pipeline when self-calibrating with the grid. We are able to interpolate these coefficients to apply to any unresolved source not on the grid points, resulting in an up to 70% smaller standard deviation on the residual deviation from linearity. The FWHM is up to 20% narrower. The depth of the fringes is now consistent up the ramp. Pointing-specific linearity corrections allow us to fix the systematic deviation in the slopes. We demonstrated this for unresolved sources. The discovered trends with PSF sampling suggest that, we may be able to model ramps for spatially extended and resolved illumination as well., Comment: 18 pages, 20 figures, Accepted for publication in A&A

Editing 2D icon images can require significant manual effort from designers. It involves manipulating multiple geometries while maintaining the logical or physical coherence of the objects depicted in the image. Previous language driven image editing methods can change the texture and geometry of objects in the image but fail at producing spatial variations, i.e. modifying spatial relations between objects while maintaining their identities. We present a language driven editing method that can produce spatial variations of icon images. Our method takes in an icon image along with a user's editing request text prompt and outputs an edited icon image reflecting the user's editing request. Our method is designed based on two key observations: (1) A user's editing requests can be translated by a large language model (LLM), with help from a domain specific language (DSL) library, into to a set of geometrical constraints defining the relationships between segments in an icon image. (2) Optimizing the affine transformations of the segments with respect to these geometrical constraints can produce icon images that fulfill the editing request and preserve overall physical and logical coherence. Quantitative and qualitative results show that our system outperforms multiple baselines, enabling natural editing of icon images.

The Small Magellanic Cloud (SMC) shows a large variation in ultraviolet (UV) dust extinction curves, ranging from Milky Way-like (MW) to significantly steeper curves with no detectable 2175 A bump. This result is based on a sample of only nine sightlines. From HST/STIS and IUE spectra of OB stars, we have measured UV extinction curves along 32 SMC sightlines where eight of these curves were published previously. We find 16 sightlines with steep extinction with no detectable 2175 A bump, four sightlines with MW-like extinction with a detectable 2175 A bump, two sightlines with fairly flat UV extinction and weak/absent 2175 A bumps, and 10 sightlines with unreliable curves due to low SMC dust columns. Our expanded sample shows that the sightlines with and without the 2175 A bump are located throughout the SMC and not limited to specific regions. The average extinction curve of the 16 bumpless sightlines is very similar to the previous average based on four sightlines. We find no correlation between dust column and the strength of the 2175 A bump. We test the hypothesis that the 2175 A bump is due to the same dust grains that are responsible for the mid-infrared carbonaceous (PAH) emission features and find they are correlated, confirming recent work in the MW. Overall, the slope of the UV extinction increases as the amplitudes of the 2175 A bump and far-UV curvature decrease. Finally, the UV slope is correlated with $N(HI)/A(V)$ and the 2175 A bump and nonlinear far-UV rise amplitudes are anti-correlated with $N(HI)/A(V)$., Comment: 24 pages, 12 figures, ApJ, accepted

Mid-infrared emission features probe the properties of ionized gas, and hot or warm molecular gas. The Orion Bar is a frequently studied photodissociation region (PDR) containing large amounts of gas under these conditions, and was observed with the MIRI IFU aboard JWST as part of the "PDRs4All" program. The resulting IR spectroscopic images of high angular resolution (0.2") reveal a rich observational inventory of mid-IR emission lines, and spatially resolve the substructure of the PDR, with a mosaic cutting perpendicularly across the ionization front and three dissociation fronts. We extracted five spectra that represent the ionized, atomic, and molecular gas layers, and measured the most prominent gas emission lines. An initial analysis summarizes the physical conditions of the gas and the potential of these data. We identified around 100 lines, report an additional 18 lines that remain unidentified, and measured the line intensities and central wavelengths. The H I recombination lines originating from the ionized gas layer bordering the PDR, have intensity ratios that are well matched by emissivity coefficients from H recombination theory, but deviate up to 10% due contamination by He I lines. We report the observed emission lines of various ionization stages of Ne, P, S, Cl, Ar, Fe, and Ni, and show how certain line ratios vary between the five regions. We observe the pure-rotational H$_2$ lines in the vibrational ground state from 0-0 S(1) to 0-0 S(8), and in the first vibrationally excited state from 1-1 S(5) to 1-1 S(9). We derive H$_2$ excitation diagrams, and approximate the excitation with one thermal (~700 K) component representative of an average gas temperature, and one non-thermal component (~2700 K) probing the effect of UV pumping. We compare these results to an existing model for the Orion Bar PDR and highlight the differences with the observations., Comment: 26 pages, 12 figures, 3 tables. Submitted to A&A, under review (1st revision)

The Mid-Infrared Instrument (MIRI) aboard the James Webb Space Telescope (JWST) provides the observatory with a huge advance in mid-infrared imaging and spectroscopy covering the wavelength range of 5 to 28 microns. This paper describes the performance and characteristics of the MIRI imager as understood during observatory commissioning activities, and through its first year of science operations. We discuss the measurements and results of the imager's point spread function, flux calibration, background, distortion and flat fields as well as results pertaining to best observing practices for MIRI imaging, and discuss known imaging artefacts that may be seen during or after data processing. Overall, we show that the MIRI imager has met or exceeded all its pre-flight requirements, and we expect it to make a significant contribution to mid-infrared science for the astronomy community for years to come.

Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photo-dissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, impacting planet formation within the disks. We report JWST and Atacama Large Millimetere Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modelling their kinematics and excitation allows us to constrain the physical conditions within the gas. We quantify the mass-loss rate induced by the FUV irradiation, finding it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk.

Microscopy enables detailed visualization and understanding of minute structures or processes. While cameras have significantly advanced optical, infrared, and electron microscopy, imaging nuclear magnetic resonance (NMR) signals on a camera has remained elusive. Here, we employ nitrogen-vacancy (NV) centers in diamond as a quantum sensor, which converts NMR signals into optical signals that are subsequently captured by a high-speed camera. Unlike traditional magnetic resonance imaging (MRI), our method records the NMR signal over a wide field of view in real space. We demonstrate that our optical widefield NMR microscopy (OMRM) can image NMR signals in microfluidic structures with a $\sim 10\,\mu m$ resolution across a $\sim 235 \times 150\,\mu m^2$ area. Crucially, each camera pixel records an NMR spectrum providing multicomponent information about the signal's amplitude, phase, local magnetic field strengths, and gradients. The fusion of optical microscopy and NMR techniques enables multifaceted imaging applications in the physical and life sciences.

The cycling of metals between interstellar gas and dust is a critical aspect of the baryon cycle of galaxies, yet our understanding of this process is limited. This study focuses on understanding dust depletion effects in the low metallicity regime (< 20% Zo) typical of cosmic noon. Using medium-resolution UV spectroscopy from the COS onboard the Hubble Space Telescope, gas-phase abundances and depletions of iron and sulfur were derived toward 18 sightlines in local dwarf galaxies IC 1613 and Sextans A. The results show that the depletion of Fe and S is consistent with that found in the Milky Way, LMC and SMC. The depletion level of Fe increases with gas column density, indicating dust growth in the interstellar medium (ISM). The level of Fe depletion decreases with decreasing metallicity, resulting in the fraction of iron in gas ranging from 3% in the MW to 9% in IC 1613 and ~19% in Sextans A. The dust-to-gas and dust-to-metal ratios (D/G, D/M) for these dwarf galaxies were estimated based on the MW relations between the depletion of Fe and other elements. The study finds that D/G decreases only slightly sub-linearly with metallicity, with D/M decreasing from 0.41 +/- 0.05 in the MW to 0.11 +/- 0.11 at 0.10 Zo (at log N(H) = 21 cm-2). The trend of D/G vs. metallicity using depletion in local systems is similar to that inferred in Damped Ly-alpha systems from abundance ratios but lies higher than the trend inferred from FIR measurements in nearby galaxies.

Optical frequency division (OFD) has revolutionized microwave and mmWave generation and set spectral purity records owing to its unique capability to transfer high fractional stability from optical to electronic frequencies. Recently, rapid developments in integrated optical reference cavities and microresonator-based optical frequency combs (microcombs) have created a path to transform OFD technology to chip scale. Here, we demonstrate an ultra-low phase noise mmWave oscillator by leveraging integrated photonic components and Kerr optical frequency division. The oscillator derives its stability from an integrated CMOS-compatible SiN coil cavity, and the optical frequency division is achieved spontaneously through Kerr interaction between the injected reference lasers and soliton microcombs in the integrated SiN microresonator. Besides achieving record-low phase noise for integrated mmWave oscillators, our demonstration greatly simplifies the implementation of integrated OFD oscillators and could be useful in applications of Radar, spectroscopy, and astronomy., Comment: 8 pages, 5 figures

This paper presents BrepGen, a diffusion-based generative approach that directly outputs a Boundary representation (B-rep) Computer-Aided Design (CAD) model. BrepGen represents a B-rep model as a novel structured latent geometry in a hierarchical tree. With the root node representing a whole CAD solid, each element of a B-rep model (i.e., a face, an edge, or a vertex) progressively turns into a child-node from top to bottom. B-rep geometry information goes into the nodes as the global bounding box of each primitive along with a latent code describing the local geometric shape. The B-rep topology information is implicitly represented by node duplication. When two faces share an edge, the edge curve will appear twice in the tree, and a T-junction vertex with three incident edges appears six times in the tree with identical node features. Starting from the root and progressing to the leaf, BrepGen employs Transformer-based diffusion models to sequentially denoise node features while duplicated nodes are detected and merged, recovering the B-Rep topology information. Extensive experiments show that BrepGen advances the task of CAD B-rep generation, surpassing existing methods on various benchmarks. Results on our newly collected furniture dataset further showcase its exceptional capability in generating complicated geometry. While previous methods were limited to generating simple prismatic shapes, BrepGen incorporates free-form and doubly-curved surfaces for the first time. Additional applications of BrepGen include CAD autocomplete and design interpolation. The code, pretrained models, and dataset are available at https://github.com/samxuxiang/BrepGen., Comment: Accepted to ACM SIGGRAPH 2024. Code at https://github.com/samxuxiang/BrepGen

Forty years ago it was proposed that gas phase organic chemistry in the interstellar medium was initiated by the methyl cation CH3+, but hitherto it has not been observed outside the Solar System. Alternative routes involving processes on grain surfaces have been invoked. Here we report JWST observations of CH3+ in a protoplanetary disk in the Orion star forming region. We find that gas-phase organic chemistry is activated by UV irradiation., Comment: Published in Nature

Water is a key ingredient for the emergence of life as we know it. Yet, its destruction and reformation in space remains unprobed in warm gas. Here, we detect the hydroxyl radical (OH) emission from a planet-forming disk exposed to external far-ultraviolet (FUV) radiation with the James Webb Space Telescope. The observations are confronted with the results of quantum dynamical calculations. The highly excited OH infrared rotational lines are the tell-tale signs of H2O destruction by FUV. The OH infrared ro-vibrational lines are attributed to chemical excitation via the key reaction O+H=OH+H which seeds the formation of water in the gas-phase. We infer that the equivalent of the Earth ocean's worth of water is destroyed per month and replenished. These results show that under warm and irradiated conditions water is destroyed and efficiently reformed via gas-phase reactions. This process, assisted by diffusive transport, could reduce the HDO/H2O ratio in the warm regions of planet-forming disks., Comment: Version submitted to Nature Astronomy

(Abridged) We investigate the impact of radiative feedback from massive stars on their natal cloud and focus on the transition from the HII region to the atomic PDR (crossing the ionisation front (IF)), and the subsequent transition to the molecular PDR (crossing the dissociation front (DF)). We use high-resolution near-IR integral field spectroscopic data from NIRSpec on JWST to observe the Orion Bar PDR as part of the PDRs4All JWST Early Release Science Program. The NIRSpec data reveal a forest of lines including, but not limited to, HeI, HI, and CI recombination lines, ionic lines, OI and NI fluorescence lines, Aromatic Infrared Bands (AIBs including aromatic CH, aliphatic CH, and their CD counterparts), CO2 ice, pure rotational and ro-vibrational lines from H2, and ro-vibrational lines HD, CO, and CH+, most of them detected for the first time towards a PDR. Their spatial distribution resolves the H and He ionisation structure in the Huygens region, gives insight into the geometry of the Bar, and confirms the large-scale stratification of PDRs. We observe numerous smaller scale structures whose typical size decreases with distance from Ori C and IR lines from CI, if solely arising from radiative recombination and cascade, reveal very high gas temperatures consistent with the hot irradiated surface of small-scale dense clumps deep inside the PDR. The H2 lines reveal multiple, prominent filaments which exhibit different characteristics. This leaves the impression of a "terraced" transition from the predominantly atomic surface region to the CO-rich molecular zone deeper in. This study showcases the discovery space created by JWST to further our understanding of the impact radiation from young stars has on their natal molecular cloud and proto-planetary disk, which touches on star- and planet formation as well as galaxy evolution., Comment: 52 pages, 30 figures, submitted to A&A

The automated assembly of complex products requires a system that can automatically plan a physically feasible sequence of actions for assembling many parts together. In this paper, we present ASAP, a physics-based planning approach for automatically generating such a sequence for general-shaped assemblies. ASAP accounts for gravity to design a sequence where each sub-assembly is physically stable with a limited number of parts being held and a support surface. We apply efficient tree search algorithms to reduce the combinatorial complexity of determining such an assembly sequence. The search can be guided by either geometric heuristics or graph neural networks trained on data with simulation labels. Finally, we show the superior performance of ASAP at generating physically realistic assembly sequence plans on a large dataset of hundreds of complex product assemblies. We further demonstrate the applicability of ASAP on both simulation and real-world robotic setups. Project website: asap.csail.mit.edu, Comment: ICRA 2024

Interpreting the learned features of vision models has posed a longstanding challenge in the field of machine learning. To address this issue, we propose a novel method that leverages the capabilities of language models to interpret the learned features of pre-trained image classifiers. Our method, called TExplain, tackles this task by training a neural network to establish a connection between the feature space of image classifiers and language models. Then, during inference, our approach generates a vast number of sentences to explain the features learned by the classifier for a given image. These sentences are then used to extract the most frequent words, providing a comprehensive understanding of the learned features and patterns within the classifier. Our method, for the first time, utilizes these frequent words corresponding to a visual representation to provide insights into the decision-making process of the independently trained classifier, enabling the detection of spurious correlations, biases, and a deeper comprehension of its behavior. To validate the effectiveness of our approach, we conduct experiments on diverse datasets, including ImageNet-9L and Waterbirds. The results demonstrate the potential of our method to enhance the interpretability and robustness of image classifiers., Comment: Accepted to ICLR 2024, Reliable and Responsible Foundation Models workshop

The JWST has captured the most detailed and sharpest infrared images ever taken of the inner region of the Orion Nebula, the nearest massive star formation region, and a prototypical highly irradiated dense photo-dissociation region (PDR). We investigate the fundamental interaction of far-ultraviolet photons with molecular clouds. The transitions across the ionization front (IF), dissociation front (DF), and the molecular cloud are studied at high-angular resolution. These transitions are relevant to understanding the effects of radiative feedback from massive stars and the dominant physical and chemical processes that lead to the IR emission that JWST will detect in many Galactic and extragalactic environments. Due to the proximity of the Orion Nebula and the unprecedented angular resolution of JWST, these data reveal that the molecular cloud borders are hyper structured at small angular scales of 0.1-1" (0.0002-0.002 pc or 40-400 au at 414 pc). A diverse set of features are observed such as ridges, waves, globules and photoevaporated protoplanetary disks. At the PDR atomic to molecular transition, several bright features are detected that are associated with the highly irradiated surroundings of the dense molecular condensations and embedded young star. Toward the Orion Bar PDR, a highly sculpted interface is detected with sharp edges and density increases near the IF and DF. This was predicted by previous modeling studies, but the fronts were unresolved in most tracers. A complex, structured, and folded DF surface was traced by the H2 lines. This dataset was used to revisit the commonly adopted 2D PDR structure of the Orion Bar. JWST provides us with a complete view of the PDR, all the way from the PDR edge to the substructured dense region, and this allowed us to determine, in detail, where the emission of the atomic and molecular lines, aromatic bands, and dust originate.

(Abridged) Mid-infrared observations of photodissociation regions (PDRs) are dominated by strong emission features called aromatic infrared bands (AIBs). The most prominent AIBs are found at 3.3, 6.2, 7.7, 8.6, and 11.2 $\mu$m. The most sensitive, highest-resolution infrared spectral imaging data ever taken of the prototypical PDR, the Orion Bar, have been captured by JWST. We provide an inventory of the AIBs found in the Orion Bar, along with mid-IR template spectra from five distinct regions in the Bar: the molecular PDR, the atomic PDR, and the HII region. We use JWST NIRSpec IFU and MIRI MRS observations of the Orion Bar from the JWST Early Release Science Program, PDRs4All (ID: 1288). We extract five template spectra to represent the morphology and environment of the Orion Bar PDR. The superb sensitivity and the spectral and spatial resolution of these JWST observations reveal many details of the AIB emission and enable an improved characterization of their detailed profile shapes and sub-components. While the spectra are dominated by the well-known AIBs at 3.3, 6.2, 7.7, 8.6, 11.2, and 12.7 $\mu$m, a wealth of weaker features and sub-components are present. We report trends in the widths and relative strengths of AIBs across the five template spectra. These trends yield valuable insight into the photochemical evolution of PAHs, such as the evolution responsible for the shift of 11.2 $\mu$m AIB emission from class B$_{11.2}$ in the molecular PDR to class A$_{11.2}$ in the PDR surface layers. This photochemical evolution is driven by the increased importance of FUV processing in the PDR surface layers, resulting in a "weeding out" of the weakest links of the PAH family in these layers. For now, these JWST observations are consistent with a model in which the underlying PAH family is composed of a few species: the so-called 'grandPAHs'., Comment: 25 pages, 10 figures, to appear in A&A

The detectors in the Mid-Infrared Instrument (MIRI) of the James Webb Space Telescope (JWST) are arsenic-21 doped silicon impurity band conduction (Si:As IBC) devices and are direct descendants of the Spitzer IRAC22 long wavelength arrays (channels 3 and 4). With appropriate data processing, they can provide excellent per-23 formance. In this paper we discuss the various non-ideal behaviors of these detectors that need to be addressed24 to realize their potential. We have developed a set of algorithms toward this goal, building on experience with25 previous similar detector arrays. The MIRI-specific stage 1 pipeline algorithms, of a three stage JWST cali-26 bration pipeline, were developed using pre-flight tests on the flight detectors and flight spares and have been27 refined using flight data. This paper describes these algorithms, which are included in the first stage of the28 JWST Calibration Pipeline for the MIRI instrument.

This paper presents a novel generative model for Computer Aided Design (CAD) that 1) represents high-level design concepts of a CAD model as a three-level hierarchical tree of neural codes, from global part arrangement down to local curve geometry; and 2) controls the generation or completion of CAD models by specifying the target design using a code tree. Concretely, a novel variant of a vector quantized VAE with "masked skip connection" extracts design variations as neural codebooks at three levels. Two-stage cascaded auto-regressive transformers learn to generate code trees from incomplete CAD models and then complete CAD models following the intended design. Extensive experiments demonstrate superior performance on conventional tasks such as random generation while enabling novel interaction capabilities on conditional generation tasks. The code is available at https://github.com/samxuxiang/hnc-cad., Comment: Accepted to ICML 2023. Project website at https://hnc-cad.github.io/

Through iterative, cross-disciplinary discussions, we define and propose next-steps for Human-centered Generative AI (HGAI). We contribute a comprehensive research agenda that lays out future directions of Generative AI spanning three levels: aligning with human values; assimilating human intents; and augmenting human abilities. By identifying these next-steps, we intend to draw interdisciplinary research teams to pursue a coherent set of emergent ideas in HGAI, focusing on their interested topics while maintaining a coherent big picture of the future work landscape.

Procedural models (i.e. symbolic programs that output visual data) are a historically-popular method for representing graphics content: vegetation, buildings, textures, etc. They offer many advantages: interpretable design parameters, stochastic variations, high-quality outputs, compact representation, and more. But they also have some limitations, such as the difficulty of authoring a procedural model from scratch. More recently, AI-based methods, and especially neural networks, have become popular for creating graphic content. These techniques allow users to directly specify desired properties of the artifact they want to create (via examples, constraints, or objectives), while a search, optimization, or learning algorithm takes care of the details. However, this ease of use comes at a cost, as it's often hard to interpret or manipulate these representations. In this state-of-the-art report, we summarize research on neurosymbolic models in computer graphics: methods that combine the strengths of both AI and symbolic programs to represent, generate, and manipulate visual data. We survey recent work applying these techniques to represent 2D shapes, 3D shapes, and materials & textures. Along the way, we situate each prior work in a unified design space for neurosymbolic models, which helps reveal underexplored areas and opportunities for future research., Comment: Eurographics 2023 State-of-the-art report (STAR)

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit., Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figures

Dust extinction is one of the fundamental measurements of dust grain sizes, compositions, and shapes. Most of the wavelength dependent variations seen in Milky Way extinction are strongly correlated with the single parameter R(V)=A(V)/E(B-V). Existing R(V) dependent extinction relationships use a mixture of spectroscopic and photometry observations, hence do not fully capture all the important dust features nor continuum variations. Using four existing samples of spectroscopically measured dust extinction curves, we consistently measure the R(V) dependent extinction relationship spectroscopically from the far-ultraviolet to mid-infrared for the first time. Linear fits of A(lambda)/A(V) dependent on R(V) are done using a method that fully accounts for their significant and correlated uncertainties. These linear parameters are fit with analytic wavelength dependent functions to determine the smooth R(V) (2.3-5.6) and wavelength (912 A-32 micron) dependent extinction relationship. This relationship shows that the far-UV rise, 2175 A bump, and the three broad optical features are dependent on R(V), but the 10 and 20 micron features are not. Existing literature relationships show significant deviations compared to this relationship especially in the far-ultraviolet and infrared. Extinction curves that clearly deviate from this relationship illustrate that this relationship only describes the average behavior versus R(V). We find tentative evidence that the relationship may not be linear with 1/R(V) especially in the ultraviolet. For the first time, this relationship provides measurements of dust extinction that spectroscopically resolve the continuum and features in the ultraviolet, optical, and infrared as a function of R(V) enabling detailed studies of dust grains properties and full spectroscopic accounting for the effects of dust extinction on astrophysical objects., Comment: 16 pages, 9 figures, ApJ, in press

We explore evolution in the dust-to-gas ratio with density within four well-resolved Local Group galaxies - the LMC, SMC, M31, and M33. We do this using new ${\it Herschel}$ maps, which restore extended emission that was missed by previous ${\it Herschel}$ reductions. This improved data allows us to probe the dust-to-gas ratio across 2.5 orders of magnitude in ISM surface density. We find significant evolution in the dust-to-gas ratio, with dust-to-gas varying with density within each galaxy by up to a factor 22.4. We explore several possible reasons for this, and our favored explanation is dust grain growth in denser regions of ISM. We find that the evolution of the dust-to-gas ratio with ISM surface density is very similar between M31 and M33, despite their large differences in mass, metallicity, and star formation rate; conversely, we find M33 and the LMC to have very different dust-to-gas evolution profiles, despite their close similarity in those properties. Our dust-to-gas ratios address previous disagreement between UV- and FIR-based dust-to-gas estimates for the Magellanic Clouds, removing the disagreement for the LMC, and considerably reducing it for the SMC - with our new dust-to-gas measurements being factors of 2.4 and 2.0 greater than the previous far-infrared estimates, respectively. We also observe that the dust-to-gas ratio appears to fall at the highest densities for the LMC, M31, and M33; this is unlikely to be an actual physical phenomenon, and we posit that it may be due to a combined effect of dark gas, and changing dust mass opacity., Comment: Accepted for publication in the Astrophysical Journal

Assembly planning is the core of automating product assembly, maintenance, and recycling for modern industrial manufacturing. Despite its importance and long history of research, planning for mechanical assemblies when given the final assembled state remains a challenging problem. This is due to the complexity of dealing with arbitrary 3D shapes and the highly constrained motion required for real-world assemblies. In this work, we propose a novel method to efficiently plan physically plausible assembly motion and sequences for real-world assemblies. Our method leverages the assembly-by-disassembly principle and physics-based simulation to efficiently explore a reduced search space. To evaluate the generality of our method, we define a large-scale dataset consisting of thousands of physically valid industrial assemblies with a variety of assembly motions required. Our experiments on this new benchmark demonstrate we achieve a state-of-the-art success rate and the highest computational efficiency compared to other baseline algorithms. Our method also generalizes to rotational assemblies (e.g., screws and puzzles) and solves 80-part assemblies within several minutes., Comment: Accepted by SIGGRAPH Asia 2022. Project website: http://assembly.csail.mit.edu/

We aim to compare variations in the full-UV dust extinction curve (912-3000 Angstrom), with the HI/H$_2$/total H content along diffuse Milky Way sightlines, to investigate possible connections between ISM conditions and dust properties. We combine an existing sample of 75 UV extinction curves based on IUE and FUSE data, with atomic and molecular column densities measured through UV absorption. The H$_2$ column density data are based on existing Lyman-Werner absorption band models from earlier work on the extinction curves. Literature values for the HI column density were compiled, and improved for 23 stars by fitting a Ly$\alpha$ profile to archived spectra. We discover a strong correlation between the H$_2$ column and the far-UV extinction, and the underlying cause is a linear relationship between H$_2$ and the strength of the far-UV rise feature. This extinction does not scale with HI, and the total H column scales best with $A(V)$ instead. The carrier of the far-UV rise therefore coincides with molecular gas, and further connections are shown by comparing the UV extinction features to the molecular fraction. Variations in the gas-to-extinction ratio $N(\rm{H})/A(V)$ correlate with the UV-to-optical extinction ratio, and we speculate this could be due to coagulation or shattering effects. Based on the H$_2$ temperature, the strongest far-UV rise strengths are found to appear in colder and denser sightlines., Comment: 24 pages, 9 figures, accepted for publication in ApJ; fix missing text in generated pdf due to broken tex command

Reverse Engineering a CAD shape from other representations is an important geometric processing step for many downstream applications. In this work, we introduce a novel neural network architecture to solve this challenging task and approximate a smoothed signed distance function with an editable, constrained, prismatic CAD model. During training, our method reconstructs the input geometry in the voxel space by decomposing the shape into a series of 2D profile images and 1D envelope functions. These can then be recombined in a differentiable way allowing a geometric loss function to be defined. During inference, we obtain the CAD data by first searching a database of 2D constrained sketches to find curves which approximate the profile images, then extrude them and use Boolean operations to build the final CAD model. Our method approximates the target shape more closely than other methods and outputs highly editable constrained parametric sketches which are compatible with existing CAD software., Comment: SIGGRAPH Asia 2022 Conference Paper