Investigation of GRACE-derived Information on Forest Drought Stress Across the Contiguous US

This research derives z-score monthly groundwater storage (GWS) anomalies and z-score monthly root zone soil moisture (RZSM) anomalies from products of Gravity Recovery and Climate Experiment Data Assimilation (GRACE-DA). Z-score monthly GWS and RZSM anomalies are compared to two drought indicators: Standardized Precipitation Index (SPI) and Standardized Precipitation-Evapotranspiration Index (SPEI) to investigate the usefulness of GRACE-DA information to detect drought conditions at tree-ring sites. This study also compares z-score monthly GWS and RZSM anomalies with the Tree Ring Standardized Growth Index (TRSGI) that is resampled by bootstrapping to investigate the capability of monitoring forest drought stress. Finally, this research uses multiple linear regression to develop a model for predicting tree-ring widths at selected study sites. The results of the comparisons of z-score monthly GWS and RZSM anomalies and commonly-used drought indices (SPI and SPEI) indicate that GWS anomalies have strong correlations (\u3e 0.4) with long-term droughts (\u3e 9 months) and RZSM anomalies have strong correlations (\u3e 0.5) with short-term droughts (\u3c 3 months). The results of comparisons of TRSGI suggest that z-score monthly GWS and RZSM anomalies are significantly related to tree-ring widths with a significant level of 0.05. This research suggests that the relationships between GWS anomalies and drought indices (SPI and SPEI) and TRSGI highly depend on the geological formations, such as the types of the aquifers, and geographical environments such as the soil texture. The multiple linear regression in this paper quantifies the impacts of z-score monthly GWS and RZSM anomalies on tree-ring widths, which suggests GRACE-DA products can provide useful information to detect and predict the growth of trees. The results also suggest the predictor, monthly RZSM anomalies, is one of the most important parameters in the regression model. Overall, the study suggests that GRACE-DA information can be used to help detect and monitor the stress from drought impacts on trees at a large spatial scale. Adviser: Tsegaye Tadess

Quantitative Assessment of Drought Impacts Using XGBoost based on the Drought Impact Reporter

Under climate change, the increasing frequency, intensity, and spatial extent of drought events lead to higher socio-economic costs. However, the relationships between the hydro-meteorological indicators and drought impacts are not identified well yet because of the complexity and data scarcity. In this paper, we proposed a framework based on the extreme gradient model (XGBoost) for Texas to predict multi-category drought impacts and connected a typical drought indicator, Standardized Precipitation Index (SPI), to the text-based impacts from the Drought Impact Reporter (DIR). The preliminary results of this study showed an outstanding performance of the well-trained models to assess drought impacts on agriculture, fire, society & public health, plants & wildlife, as well as relief, response & restrictions in Texas. It also provided a possibility to appraise drought impacts using hydro-meteorological indicators with the proposed framework in the United States, which could help drought risk management by giving additional information and improving the updating frequency of drought impacts. Our interpretation results using the Shapley additive explanation (SHAP) interpretability technique revealed that the rules guiding the predictions of XGBoost comply with domain expertise knowledge around the role that SPI indicators play around drought impacts.Comment: 4 pages with 2 figures and 1 table. NeurIPS workshop on Tackling Climate Change with Machine Learning, 202

Evaluating and Improving Tool-Augmented Computation-Intensive Math Reasoning

Chain-of-thought prompting~(CoT) and tool augmentation have been validated in recent work as effective practices for improving large language models~(LLMs) to perform step-by-step reasoning on complex math-related tasks. However, most existing math reasoning datasets may be not able to fully evaluate and analyze the ability of LLMs in manipulating tools and performing reasoning, as they may only require very few invocations of tools or miss annotations for evaluating intermediate reasoning steps. To address the issue, we construct \textbf{CARP}, a new Chinese dataset consisting of 4,886 computation-intensive algebra problems with formulated annotations on intermediate steps. In CARP, we test four LLMs with CoT prompting, and find that they are all prone to make mistakes at the early steps of the solution, leading to wrong answers. Based on this finding, we propose a new approach that can deliberate the reasoning steps with tool interfaces, namely \textbf{DELI}. In DELI, we first initialize a step-by-step solution based on retrieved exemplars, then iterate two deliberation procedures that check and refine the intermediate steps of the generated solution, from the perspectives of tool manipulation and natural language reasoning, until obtaining converged solutions or reaching the maximum turn. Experimental results on CARP and six other datasets show that the proposed DELI mostly outperforms competitive baselines, and can further boost the performance of existing CoT methods. Our data and code are available in \url{https://github.com/RUCAIBox/CARP}.Comment: 17 pages, working in progres

A conjugate study of the polar ionospheric F2-layer and IRI-2007 at 75° magnetic latitude for solar minimum

Long-duration conjugate observations by the EISCAT Svalbard Radar (ESR) and the ionosonde at Zhongshan station from the International Polar Year (IPY) during solar minimum conditions are analyzed, with respect to variability in the F2-layer peak parameters. A comparison between International Reference Ionosphere- 2007 (IRI-2007) and observation data clearly demonstrates good agreement in summer, but greater deviations in winter. The IRI model reproduces the F2 peak parameters dominated by solar photoionization reasonably well, but it does not address the effect of electron precipitation. Hence, the discrepancies become large in the winter auroral ionosphere

Microwave Photonic Imaging Radar with a Millimeter-level Resolution

Microwave photonic radars enable fast or even real-time high-resolution imaging thanks to its broad bandwidth. Nevertheless, the frequency range of the radars usually overlaps with other existed radio-frequency (RF) applications, and only a centimeter-level imaging resolution has been reported, making them insufficient for civilian applications. Here, we propose a microwave photonic imaging radar with a millimeter-level resolution by introducing a frequency-stepped chirp signal based on an optical frequency shifting loop. As compared with the conventional linear-frequency modulated (LFM) signal, the frequency-stepped chirp signal can bring the system excellent capability of anti-interference. In an experiment, a frequency-stepped chirp signal with a total bandwidth of 18.2 GHz (16.9 to 35.1 GHz) is generated. Postprocessing the radar echo, radar imaging with a two-dimensional imaging resolution of ~8.5 mm$\times$~8.3 mm is achieved. An auto-regressive algorithm is used to reconstruct the disturbed signal when a frequency interference exists, and the high-resolution imaging is sustained

Genetic alteration of histone lysine methyltransferases and their significance in renal cell carcinoma

Background Histone lysine methyltransferases (HMTs), a category of enzymes, play essential roles in regulating transcription, cellular differentiation, and chromatin construction. The genomic landscape and clinical significance of HMTs in renal cell carcinoma (RCC) remain uncovered. Methods We conducted an integrative analysis of 50 HMTs in RCC and discovered the internal relations among copy number alterations (CNAs), expressive abundance, mutations, and clinical outcome. Results We confirmed 12 HMTs with the highest frequency of genetic alterations, including seven HMTs with high-level amplification, two HMTs with somatic mutation, and three HMTs with putative homozygous deletion. Patterns of copy number and expression varied among different subtypes of RCC, including clear cell renal cell carcinoma, papillary cell carcinoma, and chromophobe renal carcinoma. Kaplan–Meier survival analysis and multivariate analysis identified that CNA or mRNA expression in some HMTs were significantly associated with shorter overall patient survival. Systematic analysis identified six HMTs (ASH1L, PRDM6, NSD1, EZH2, WHSC1L1, SETD2) which were dysregulated by genetic alterations as candidate therapeutic targets. Discussion In summary, our findings strongly evidenced that genetic alteration of HMTs may play an important role in generation and development of RCC, which lays a solid foundation for the mechanism for further research in the future

Simultaneous optical and radar observations of poleward moving auroral forms under different IMF conditions

Using high temporal resolution optical data obtained from three-wavelength all-sky imagers at Chinese Yellow River Station in the Arctic, together with the EISCAT Svalbard radar (ESR) and SuperDARN radars, we investigated the dayside poleward moving auroral forms (PMAFs) and the associated plasma features in the polar ionosphere under different interplanetary magnetic field (IMF) conditions, between 0900 and 1010 UT on 22 December 2003. Simultaneous optical and ESR observations revealed that all PMAFs were clearly associated with pulsed particle precipitations. During northward IMF, particles can precipitate into lower altitudes and reach the ionospheric E-region, and there is a reverse convection cell associated with these PMAFs. This cell is one of the typical signatures of the dayside high-latitude (lobe) reconnection in the polar ionosphere. These results indicate that the PMAFs were associated with the high-latitude reconnection. During southward IMF, the PMAFs show larger latitudinal motion, indicating a longer mean lifetime, and the associated ionospheric features indicate that the PMAFs were generated by the dayside low-latitude reconnection