Crop type maps are critical for tracking agricultural land use and estimating crop production. Remote sensing has proven an efficient and reliable tool for creating these maps in regions with abundant ground labels for model training, yet these labels remain difficult to obtain in many regions and years. NASA's Global Ecosystem Dynamics Investigation (GEDI) spaceborne lidar instrument, originally designed for forest monitoring, has shown promise for distinguishing tall and short crops. In the current study, we leverage GEDI to develop wall-to-wall maps of short vs tall crops on a global scale at 10 m resolution for 2019-2021. Specifically, we show that (1) GEDI returns can reliably be classified into tall and short crops after removing shots with extreme view angles or topographic slope, (2) the frequency of tall crops over time can be used to identify months when tall crops are at their peak height, and (3) GEDI shots in these months can then be used to train random forest models that use Sentinel-2 time series to accurately predict short vs. tall crops. Independent reference data from around the world are then used to evaluate these GEDI-S2 maps. We find that GEDI-S2 performed nearly as well as models trained on thousands of local reference training points, with accuracies of at least 87% and often above 90% throughout the Americas, Europe, and East Asia. Systematic underestimation of tall crop area was observed in regions where crops frequently exhibit low biomass, namely Africa and South Asia, and further work is needed in these systems. Although the GEDI-S2 approach only differentiates tall from short crops, in many landscapes this distinction goes a long way toward mapping the main individual crop types. The combination of GEDI and Sentinel-2 thus presents a very promising path towards global crop mapping with minimal reliance on ground data.
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Most previous unsupervised domain adaptation (UDA) methods for question answering(QA) require access to source domain data while fine-tuning the model for the target domain. Source domain data may, however, contain sensitive information and may be restricted. In this study, we investigate a more challenging setting, source-free UDA, in which we have only the pretrained source model and target domain data, without access to source domain data. We propose a novel self-training approach to QA models that integrates a unique mask module for domain adaptation. The mask is auto-adjusted to extract key domain knowledge while trained on the source domain. To maintain previously learned domain knowledge, certain mask weights are frozen during adaptation, while other weights are adjusted to mitigate domain shifts with pseudo-labeled samples generated in the target domain. %As part of the self-training process, we generate pseudo-labeled samples in the target domain based on models trained in the source domain. Our empirical results on four benchmark datasets suggest that our approach significantly enhances the performance of pretrained QA models on the target domain, and even outperforms models that have access to the source data during adaptation.
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The number of international benchmarking competitions is steadily increasing in various fields of machine learning (ML) research and practice. So far, however, little is known about the common practice as well as bottlenecks faced by the community in tackling the research questions posed. To shed light on the status quo of algorithm development in the specific field of biomedical imaging analysis, we designed an international survey that was issued to all participants of challenges conducted in conjunction with the IEEE ISBI 2021 and MICCAI 2021 conferences (80 competitions in total). The survey covered participants' expertise and working environments, their chosen strategies, as well as algorithm characteristics. A median of 72% challenge participants took part in the survey. According to our results, knowledge exchange was the primary incentive (70%) for participation, while the reception of prize money played only a minor role (16%). While a median of 80 working hours was spent on method development, a large portion of participants stated that they did not have enough time for method development (32%). 25% perceived the infrastructure to be a bottleneck. Overall, 94% of all solutions were deep learning-based. Of these, 84% were based on standard architectures. 43% of the respondents reported that the data samples (e.g., images) were too large to be processed at once. This was most commonly addressed by patch-based training (69%), downsampling (37%), and solving 3D analysis tasks as a series of 2D tasks. K-fold cross-validation on the training set was performed by only 37% of the participants and only 50% of the participants performed ensembling based on multiple identical models (61%) or heterogeneous models (39%). 48% of the respondents applied postprocessing steps.
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Quantization has become a predominant approach for model compression, enabling deployment of large models trained on GPUs onto smaller form-factor devices for inference. Quantization-aware training (QAT) optimizes model parameters with respect to the end task while simulating quantization error, leading to better performance than post-training quantization. Approximation of gradients through the non-differentiable quantization operator is typically achieved using the straight-through estimator (STE) or additive noise. However, STE-based methods suffer from instability due to biased gradients, whereas existing noise-based methods cannot reduce the resulting variance. In this work, we incorporate exponentially decaying quantization-error-aware noise together with a learnable scale of task loss gradient to approximate the effect of a quantization operator. We show this method combines gradient scale and quantization noise in a better optimized way, providing finer-grained estimation of gradients at each weight and activation layer's quantizer bin size. Our controlled noise also contains an implicit curvature term that could encourage flatter minima, which we show is indeed the case in our experiments. Experiments training ResNet architectures on the CIFAR-10, CIFAR-100 and ImageNet benchmarks show that our method obtains state-of-the-art top-1 classification accuracy for uniform (non mixed-precision) quantization, out-performing previous methods by 0.5-1.2% absolute.
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Sampling diverse programs from a code language model and reranking with model likelihood is a popular method for code generation but it is prone to preferring degenerate solutions. Inspired by collaborative programming, we propose Coder-Reviewer reranking. We augment Coder language models from past work, which generate programs given language instructions, with Reviewer models, which evaluate the likelihood of the instruction given the generated programs. We perform an extensive study across six datasets with eight models from three model families. Experimental results show that Coder-Reviewer reranking leads to consistent and significant improvement (up to 17% absolute accuracy gain) over reranking with the Coder model only. When combined with executability filtering, Coder-Reviewer reranking can often outperform the minimum Bayes risk method. Coder-Reviewer reranking is easy to implement by prompting, can generalize to different programming languages, and works well with off-the-shelf hyperparameters.
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我们介绍了第一个机器学习引力波搜索模拟数据挑战(MLGWSC-1)的结果。在这一挑战中,参与的小组必须从二进制黑洞合并中识别出复杂性和持续时间逐渐嵌入在逐渐更现实的噪声中的引力波信号。 4个提供的数据集中的决赛包含O3A观察的真实噪声,并发出了20秒的持续时间,其中包含进动效应和高阶模式。我们介绍了在提交前从参与者未知的1个月的测试数据中得出的6个输入算法的平均灵敏度距离和运行时。其中4个是机器学习算法。我们发现,最好的基于机器学习的算法能够以每月1个的错误警报率(FAR)的速度(FAR)实现基于匹配过滤的生产分析的敏感距离的95%。相反,对于真实的噪音,领先的机器学习搜索获得了70%。为了更高的范围,敏感距离缩小的差异缩小到某些数据集上选择机器学习提交的范围$ \ geq 200 $以优于传统搜索算法的程度。我们的结果表明,当前的机器学习搜索算法可能已经在有限的参数区域中对某些生产设置有用。为了改善最新的技术,机器学习算法需要降低他们能够检测信号并将其有效性扩展到参数空间区域的虚假警报率,在这些区域中,建模的搜索在计算上很昂贵。根据我们的发现,我们汇编了我们认为,将机器学习搜索提升到重力波信号检测中的宝贵工具,我们认为这是最重要的研究领域。
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噪声的去除或取消对成像和声学具有广泛的应用。在日常生活中,Denoising甚至可能包括对地面真理不忠的生成方面。但是,对于科学应用,denoing必须准确地重现地面真相。在这里,我们展示了如何通过深层卷积神经网络来定位数据,从而以定量精度出现弱信号。特别是,我们研究了晶体材料的X射线衍射。我们证明,弱信号是由电荷排序引起的,在嘈杂的数据中微不足道的信号,在DeNo的数据中变得可见和准确。通过对深度神经网络的监督培训,具有成对的低噪声数据,可以通过监督培训来实现这一成功。这样,神经网络就可以了解噪声的统计特性。我们证明,使用人造噪声(例如泊松和高斯)不会产生这种定量准确的结果。因此,我们的方法说明了一种实用的噪声过滤策略,可以应用于具有挑战性的获取问题。
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招聘和大学录取等许多申请涉及申请人的评估和选择。这些任务在根本上是困难的,并且需要从多个不同方面(我们称为“属性”)结合证据。在这些应用程序中,申请人的数量通常很大,一个常见的做法是以分布式方式将任务分配给多个评估人员。具体而言,在经常使用的整体分配中,每个评估者都会分配申请人的子集,并要求评估其分配的申请人的所有相关信息。但是,这样的评估过程受到诸如错误校准的问题的约束(评估人员仅见一小部分申请人,并且可能没有良好的相对质量感)和歧视(评估者受到有关申请人无关的信息的影响)。我们确定基于属性的评估允许替代分配方案。具体而言,我们考虑分配每个评估者更多的申请人,但每个申请人的属性更少,称为分割分配。我们通过理论和实验方法比较了分段分配与几个维度的整体分配。我们在这两种方法之间建立了各种折衷方案,并确定一种方法在其中一种方法比另一种方法更准确地评估。
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ICECUBE是一种用于检测1 GEV和1 PEV之间大气和天体中微子的光学传感器的立方公斤阵列,该阵列已部署1.45 km至2.45 km的南极的冰盖表面以下1.45 km至2.45 km。来自ICE探测器的事件的分类和重建在ICeCube数据分析中起着核心作用。重建和分类事件是一个挑战,这是由于探测器的几何形状,不均匀的散射和冰中光的吸收,并且低于100 GEV的光,每个事件产生的信号光子数量相对较少。为了应对这一挑战,可以将ICECUBE事件表示为点云图形,并将图形神经网络(GNN)作为分类和重建方法。 GNN能够将中微子事件与宇宙射线背景区分开,对不同的中微子事件类型进行分类,并重建沉积的能量,方向和相互作用顶点。基于仿真,我们提供了1-100 GEV能量范围的比较与当前ICECUBE分析中使用的当前最新最大似然技术,包括已知系统不确定性的影响。对于中微子事件分类,与当前的IceCube方法相比,GNN以固定的假阳性速率(FPR)提高了信号效率的18%。另外,GNN在固定信号效率下将FPR的降低超过8(低于半百分比)。对于能源,方向和相互作用顶点的重建,与当前最大似然技术相比,分辨率平均提高了13%-20%。当在GPU上运行时,GNN能够以几乎是2.7 kHz的中位数ICECUBE触发速率的速率处理ICECUBE事件,这打开了在在线搜索瞬态事件中使用低能量中微子的可能性。
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由于Covid-19-19疫苗可用,因此没有研究量化不同的灾难疏散策略如何减轻避难所中的大流行风险。因此,我们应用了一个年龄结构化的流行病学模型,称为易感性暴露感染(SEIR)模型,以研究台湾不同的疫苗摄取水平以及在台湾实施的转移方案在多大程度上降低了感染和延迟流行峰值的情况。台湾的转移协议涉及转移因曝光而自我占用的人,从而阻止了他们与集体庇护所的普通公众融合。转移方案,结合足够的疫苗摄取,可以减少相对于没有这种策略的情况,相对于场景,感染的最大数量和延迟爆发。当所有暴露的人的转移是不可能的,或者疫苗的摄取不足时,转移方案仍然很有价值。此外,一组主要由年轻人人口组成的撤离者往往会早日出现大流行峰值,并且在实施转移方案时,多数老年人组的感染比多数老年人多。但是,当不执行转移方案时,多数老年人群体比大多数年轻成人群体高达20%。
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