MeMOTR: Long-Term Memory-Augmented Transformer for Multi-Object Tracking

As a video task, Multiple Object Tracking (MOT) is expected to capture temporal information of targets effectively. Unfortunately, most existing methods only explicitly exploit the object features between adjacent frames, while lacking the capacity to model long-term temporal information. In this paper, we propose MeMOTR, a long-term memory-augmented Transformer for multi-object tracking. Our method is able to make the same object's track embedding more stable and distinguishable by leveraging long-term memory injection with a customized memory-attention layer. This significantly improves the target association ability of our model. Experimental results on DanceTrack show that MeMOTR impressively surpasses the state-of-the-art method by 7.9% and 13.0% on HOTA and AssA metrics, respectively. Furthermore, our model also outperforms other Transformer-based methods on association performance on MOT17 and generalizes well on BDD100K. Code is available at https://github.com/MCG-NJU/MeMOTR.Comment: Accepted by ICCV 2023. In the latest version, we report the results on SportsMO

Study of gas flow dynamics in porous and granular media with laser-polarized ¹²⁹Xe NMR

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2005.Includes bibliographical references (p. 173-182).This thesis presents Nuclear Magnetic Resonance (NMR) studies of gas flow dynamics in porous and granular media by using laser-polarized ¹²⁹Xe . Two different physical processes, the gas transport in porous rock cores and the mass exchanges between different phases in fluidized granular systems, were investigated and new experimental methods were designed to measure several important parameters characterizing the two systems. Methods for measuring the parameters had been either unavailable or significantly limited previously. The research involved modeling the gas flow in porous and granular media by relating the dynamics of spin magnetization to the interesting parameters, as well as correspondingly designing new measurement methods and verifying them on the laboratory test beds. We proposed a simple method to measure two important parameters of reservoir rocks, permeability and effective porosity, by probing the flow front of laser-polarized xenon gas inside the rock cores. The method was thoroughly tested on different categories of rocks with permeability values spanning two orders of magnitude, and the results were in agreement with those from the established techniques.(cont.) The uniqueness in the work is that the fast method developed is capable of measuring the two parameters simultaneously on the same setup. Bubble-emulsion exchange and emulsion-adsorption exchange in a fluidized bed are two processes crucial to the efficiency of many chemical reactors working in bubbling regime. We used differences in T2 and chemical shift to contrast the three phases in the xenon spectra, and designed methods to measure the inter-phase exchange rates. The measured results of the bubble-emulsion and emulsion-adsorption exchange rates agreed well with predictions based on available theory. Our approach is the first to non-invasively probe natural bubbles in a three-dimensional bed, and to measure the exchange rate between the emulsion phase and multiple bubbles.by Ruopeng Wang.Ph.D

A multi-bit delta sigma audio digital-to-analog converter

Digital-to-analog converters (DACs) with wide dynamic range and high linearity are required for high-end audio applications. A multi-bit delta sigma audio DAC, using a novel gain-correction technique, is described in this thesis. For widely varying on-chip RC time constant, the DAC gain can be accurately controlled by the correction circuitry. To overcome the nonlinearity caused by the mismatches of the internal unit-element DAC, a new dynamic element matching (DEM) algorithm, named split-set data-weighted averaging (SDWA), is proposed. In-band tones can be effectively removed by the proposed algorithm while signalto- noise ratio (SNR) is high. Hardware implementation of SDWA is cost-effective and low-latency which makes it practical in high speed applications. A headphone driver integrated together with the analog reconstruction filter in the delta sigma audio DAC allows the designed DAC to driver the headphone directly. An experimental headphone driver was designed and fabricated in a 0.35mm CMOS technology. The prototype delta sigma audio DAC integrated with the headphone driver was built using the same technology. Simulation and measured results show that they both meet the requirements for a typical high-end audio system

Dynamic MDETR: A Dynamic Multimodal Transformer Decoder for Visual Grounding

Multimodal transformer exhibits high capacity and flexibility to align image and text for visual grounding. However, the existing encoder-only grounding framework (e.g., TransVG) suffers from heavy computation due to the self-attention operation with quadratic time complexity. To address this issue, we present a new multimodal transformer architecture, coined as Dynamic Mutilmodal DETR (Dynamic MDETR), by decoupling the whole grounding process into encoding and decoding phases. The key observation is that there exists high spatial redundancy in images. Thus, we devise a new dynamic multimodal transformer decoder by exploiting this sparsity prior to speed up the visual grounding process. Specifically, our dynamic decoder is composed of a 2D adaptive sampling module and a text guided decoding module. The sampling module aims to select these informative patches by predicting the offsets with respect to a reference point, while the decoding module works for extracting the grounded object information by performing cross attention between image features and text features. These two modules are stacked alternatively to gradually bridge the modality gap and iteratively refine the reference point of grounded object, eventually realizing the objective of visual grounding. Extensive experiments on five benchmarks demonstrate that our proposed Dynamic MDETR achieves competitive trade-offs between computation and accuracy. Notably, using only 9% feature points in the decoder, we can reduce ~44% GFLOPs of the multimodal transformer, but still get higher accuracy than the encoder-only counterpart. In addition, to verify its generalization ability and scale up our Dynamic MDETR, we build the first one-stage CLIP empowered visual grounding framework, and achieve the state-of-the-art performance on these benchmarks.Comment: Accepted by IEEE Transactions on Pattern Analysis and Machine Intelligence (TPAMI) in October 202

Diffusion MR Tractography of the Heart

Histological studies have shown that the myocardium consists of an array of crossing helical fiber tracts. Changes in myocardial fiber architecture occur in ischemic heart disease and heart failure, and can be imaged non-destructively with diffusion-encoded MR. Several diffusion-encoding schemes have been developed, ranging from scalar measurements of mean diffusivity to a 6-dimensional imaging technique known as diffusion spectrum imaging or DSI. The properties of DSI make it particularly suited to the generation of 3-dimensional tractograms of myofiber architecture. In this article we review the physical basis of diffusion-tractography in the myocardium and the attributes of the available techniques, placing particular emphasis on DSI. The application of DSI in ischemic heart disease is reviewed, and the requisites for widespread clinical translation of diffusion MR tractography in the heart are discussed

Impact of soda tax on beverage price, sale, purchase, and consumption in the US: a systematic review and meta-analysis of natural experiments

BackgroundAs a primary source of added sugars in the US diet, sugar-sweetened beverage (SSB) consumption is presumed to contribute to obesity prevalence and poor oral health. We systematically synthesized and quantified evidence from US-based natural experiments concerning the impact of SSB taxes on beverage prices, sales, purchases, and consumption.MethodsA keyword and reference search was performed in PubMed, Web of Science, Cochrane Library, Scopus, and EconLit from the inception of an electronic bibliographic database to Oct 31, 2022. Meta-analysis was conducted to estimate the pooled effect of soda taxes on SSB consumption, prices, passthrough rate, and purchases.ResultsTwenty-six natural experiments, all adopting a difference-in-differences approach, were included. Studies assessed soda taxes in Berkeley, Oakland, and San Francisco in California, Philadelphia in Pennsylvania, Boulder in Colorado, Seattle in Washington, and Cook County in Illinois. Tax rates ranged from 1 to 2 ¢/oz. The imposition of the soda tax was associated with a 1.06 ¢/oz. (95% confidence interval [CI] = 0.90, 1.22) increase in SSB prices and a 27.3% (95% CI = 19.3, 35.4%) decrease in SSB purchases. The soda tax passthrough rate was 79.7% (95% CI = 65.8, 93.6%). A 1 ¢/oz. increase in soda tax rate was associated with increased prices of SSBs by 0.84 ¢/oz (95% CI = 0.33, 1.35).ConclusionSoda taxes could be effective policy leverage to nudge people toward purchasing and consuming fewer SSBs. Future research should examine evidence-based classifications of SSBs, targeted use of revenues generated by taxes to reduce health and income disparities, and the feasibility of redesigning the soda tax to improve efficiency

Doping inorganic ions to regulate bioactivity of Ca–P coating on bioabsorbable high purity magnesium

AbstractPerformance of biomaterials was strongly affected by their surface properties and could be designed artificially to meet specific biomedical requirements. In this study, F−(F), SiO42−(Si), or HCO3−(C)-doped Ca–P coatings were fabricated by biomimetic deposition on the surface of biodegradable high-purity magnesium (HP Mg). The crystalline phases, morphologies and compositions of Ca–P coatings had been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The biomineralization and corrosion resistance of doped Ca–P coatings had also been investigated. The results showed that the Ca–P coating with or without doped elements mainly contained the plate-like dicalcium phosphate dehydrate (DCPD) phase. The doped F, Si, or C changed the surface morphology of Ca–P coatings after mineralization. Doped F enhanced the mineralization of Ca–P coating, and doped Si retarded the mineralization of Ca–P coating. However, H2 evolution of HP Mg discs with different Ca–P coatings was close to 0.4–0.7ml/cm2 after two-week immersion. That meant that the corrosion resistance of the Ca–P coatings with different or without doped elements did not change significantly

A FreeSurfer-compliant consistent manual segmentation of infant brains spanning the 0-2 year age range

We present a detailed description of a set of FreeSurfer compatible segmentation guidelines tailored to infant MRI scans, and a unique data set of manually segmented acquisitions, with subjects nearly evenly distributed between 0 and 2 years of age. We believe that these segmentation guidelines and this dataset will have a wide range of potential uses in medicine and neuroscience.Eunice Kennedy Shriver National Institute of Child Health and Human Development (U.S.) (Grant 1K99HD061485-01A1)Eunice Kennedy Shriver National Institute of Child Health and Human Development (U.S.) (Grant R00 HD061485-03)Ralph Schlaeger FellowshipNational Institutes of Health (U.S.) (1R01EB014947-01)National Institutes of Health (U.S.) (K23 NS42758-01)National Center for Research Resources (U.S.) (P41-RR14075)National Center for Research Resources (U.S.) (U24 RR021382)National Institutes of Health. National Institute for Biomedical Imaging and Bioengineering (R01EB006758)National Institute on Aging (AG022381)National Institute on Aging (5R01AG008122-22)National Institute of Neurological Disorders and Stroke (U.S.) (R01 NS052585-01)National Institute of Neurological Disorders and Stroke (U.S.) (1R21NS072652-01)National Institute of Neurological Disorders and Stroke (U.S.) (1R01NS070963)National Center for Research Resources (U.S.) (Shared Instrumentation Grant 1S10RR023401)National Center for Research Resources (U.S.) (Shared Instrumentation Grant 1S10RR019307)National Center for Research Resources (U.S.) (Shared Instrumentation Grant 1S10RR023043)Ellison Medical FoundationNational Institutes of Health. Blueprint for Neuroscience Research (5U01-MH093765)Human Connectome Projec

Study of Gas-Fluidization Dynamics with Laser-Polarized Xe-129

Abstract We report initial NMR studies of gas dynamics in a particle bed fluidized by laser-polarized xenon ( 129 Xe) gas. We have made preliminary measurements of two important characteristics: gas exchange between the bubble and emulsion phases and the gas velocity distribution in the bed. We used T 2 * contrast to differentiate the bubble and emulsion phases by choosing solid particles with large magnetic susceptibility. Experimental tests demonstrated that this method was successful in eliminating 129 Xe magnetization in the emulsion phase, which enabled us to observe the time dependence of the bubble magnetization. By employing the pulsed field gradient method, we also measured the gas velocity distribution within the bed. These results clearly show the onset of bubbling and can be used to deduce information about gas and particle motion in the fluidized bed.