Privacy Implications of Retrieval-Based Language Models

Retrieval-based language models (LMs) have demonstrated improved interpretability, factuality, and adaptability compared to their parametric counterparts, by incorporating retrieved text from external datastores. While it is well known that parametric models are prone to leaking private data, it remains unclear how the addition of a retrieval datastore impacts model privacy. In this work, we present the first study of privacy risks in retrieval-based LMs, particularly $k$NN-LMs. Our goal is to explore the optimal design and training procedure in domains where privacy is of concern, aiming to strike a balance between utility and privacy. Crucially, we find that $k$NN-LMs are more susceptible to leaking private information from their private datastore than parametric models. We further explore mitigations of privacy risks. When privacy information is targeted and readily detected in the text, we find that a simple sanitization step would completely eliminate the risks, while decoupling query and key encoders achieves an even better utility-privacy trade-off. Otherwise, we consider strategies of mixing public and private data in both datastore and encoder training. While these methods offer modest improvements, they leave considerable room for future work. Together, our findings provide insights for practitioners to better understand and mitigate privacy risks in retrieval-based LMs. Our code is available at: https://github.com/Princeton-SysML/kNNLM_privacy

Combat molten aluminum corrosion of AISI H13 steel by lowtemperature liquid nitrocarburizing

Possibility of improving the resistance of AISI H13 steel to molten aluminum corrosion by liquid nitrocarburizing (LNC) was explored. The effects of the LNC parameters in terms of temperatures (703/723/743K) and soaking time (4/8/12h) on phase transformation, microstructure, and resistance to molten aluminum were fully studied. The surface phase compositions and the cross-sectional phase distribution of the LNC treated specimens were studied by implementable X-ray diffraction analysis. Microstructure, element distribution, microhardness, and the kinetics of the nitrocarburized case formation were fully researched. Immersion test of corrosion resistance to molten aluminum was carried out at 1023K for 30min. It is observed that an oxide layer can be produced on the top of the nitrocarburized case during LNC treatment, which cannot be regularly produced by other nitriding methods. The nitrocarburized case consists of a compound layer, a diffusion layer, and a transition layer. The growth of the nitrocarburized case is proportional to the squared treatment time and follows the Arrhenius law for the treatment temperature. The activation energy is estimated to be 195.4 kJ·mol−1. While the nitrocarburized case provided limited resistance to molten aluminum, the oxide layer formed on the top of the nitrocarburized case conferred significantly improved molten aluminum corrosion resistance, especially a duplex oxide layer produced at 743

Distinguishing T1-2 and T3a tumors of rectal cancer with texture analysis and functional MRI parameters

PURPOSEWe aimed to investigate whether the texture analysis and functional magnetic resonance imaging (fMRI) could differentiate rectal cancer pathological stages T1-2 (pT1-2) and T3a (pT3a).METHODSEighty-two rectal adenocarcinoma patients at stage pT1-2 and pT3a received T2 and fMRI examination before surgery. The latter included apparent diffusion coefficient (ADC) sequence, dynamic contrast enhancement (DCE) MRI, and intravoxel incoherent motion (IVIM) diffusion weighted imaging. Patients were grouped into early stage (pT1-2) and advanced stage (pT3a). The MRI accuracy in diagnosing rectal cancer before surgery was calculated. The differences in clinicopathological variables, quantitative parameters including ADC values, IVIM parameters (perfusion fraction [f], true diffusion coefficient [D], and pseudo- diffusion coefficient [D*]), DCE MRI parameters (transfer constant [Ktrans], reflux constant [Kep], and extravascular extracellular fractional volume [Ve]), and texture features were compared between the groups. Receiver operating characteristic (ROC) curves of texture features and fMRI parameters were generated to distinguish pT1-2 and pT3a tumors. The multivariate analysis was used to develop a predictive model and to find independent risk factors. Hosmer–Lemeshow test was used to see the fitness of the model. DeLong test was applied to compare the ROC curves of different features. Correlation of texture features and fMRI parameters with stage were calculated using r (Spearman’s rank correlation coefficient).RESULTSThe preoperative accuracy in differentiating pT1-2 from pT3a rectal cancer using MRI was 74.39%. Kep, Ve, and ADC showed significant differences between the groups. Kep and ADC showed negative correlation with stage. Ve correlated positively with stage. Twenty-five texture features from T2 images showed significant differences between groups, and S(0,2)SumOfSqs and WavEnLH_s_2 among these showed better performance, showing negative correlation with stage. The area under the curve (AUC) values of S(0,2)SumOfSqs, WavEnLH_s_2, ADC, Kep, and Ve were 0.721, 0.699, 0.690, 0.666, and 0.653, respectively. The multivariate analysis showed that S(0,2) SumOfSqs, WavEnLH_s_2, and ADC are risk factors for advanced tumors, and the logistic model built by Kep, Ve, S(0,2)SumOfSqs, WavEnLH_s_2, and ADC has the AUC, sensitivity, and specificity of 0.833, 88.5%, and 73.3%, respectively. ROC curve of the model showed statistical significance between S(0,2)SumOfSqs, ADC, Kep, and Ve. The P value of the Hosmer–Lemeshow test was 0.65.CONCLUSIONS(0,2)SumOfSqs, WavEnLH_s_2, and ADC are risk factors for advanced rectal cancer, and the model built by Kep, Ve, S(0,2)SumOfSqs, WavEnLH_s_2, and ADC has better performance than using a single method. The application of above combinations could be beneficial to patients’ accurate and individualized treatments

Developmental differences in the influence of phonological similarity on spoken word processing in Mandarin Chinese.

The developmental trajectory of spoken word recognition has been well established in Indo-European languages, but to date remains poorly characterized in Mandarin Chinese. In this study, typically developing children (N=17; mean age 10; 5) and adults (N=17; mean age 24) performed a picture-word matching task in Mandarin while we recorded ERPs. Mismatches diverged from expectations in different components of the Mandarin syllable; namely, word-initial phonemes, word-final phonemes, and tone. By comparing responses to different mismatch types, we uncovered evidence suggesting that both children and adults process words incrementally. However, we also observed key developmental differences in how subjects treated onset and rime mismatches. This was taken as evidence for a stronger influence of top-down processing on spoken word recognition in adults compared to children. This work therefore offers an important developmental component to theories of Mandarin spoken word recognition

Experimental and numerical studies on progressive debonding of grouted rock bolts

Understanding the mechanism of progressive debonding of bolts is of great significance for underground safety. In this paper, both laboratory experiment and numerical simulation of the pull-out tests were performed. The experimental pull-out test specimens were prepared using cement mortar material, and a relationship between the pull-out strength of the bolt and the uniaxial compressive strength (UCS) of cement mortar material specimen was established. The locations of crack developed in the pull-out process were identified using the acoustic emission (AE) technique. The pull-out test was reproduced using 2D Particle Flow Code (PFC2D) with calibrated parameters. The experimental results show that the axial displacement of the cement mortar material at the peak load during the test was approximately 5 mm for cement-based grout of all strength. In contrast, the peak load of the bolt increased with the UCS of the confining medium. Under peak load, cracks propagated to less than one half of the anchorage length, indicating a lag between crack propagation and axial bolt load transmission. The simulation results show that the dilatation between the bolt and the rock induced cracks and extended the force field along the anchorage direction; and, it was identified as the major contributing factor for the pull-out failure of rock bolt

Parametric studies of cable bolts using a modified Short Encapsulation Pull-out Test

The laboratory short encapsulation pull out test (LSEPT) has been widely accepted as the most efficient method to characterize the mechanical behaviour of cable bolts under axial loading. In this study, a number of LSEPTs was performed on conventional cable bolts including Plain SuperStrand and TG cable bolts using the improved pull out test design. The effects of several parameters including the uniaxial compressive strength (UCS) of confining medium and grout and the borehole diameter on the mechanical behaviour of both cable bolts were investigated. Analysis of Variance (ANOVA) was employed to quantify the contribution of these parameters on the responses including peak and residual loads and initial stiffness. ANOVA revealed that UCS of confining medium and grout is the key contributing factor to the mechanical behaviour of Plain SuperStrand cable bolt. Also, it was demonstrated that the borehole diameter had a negligible impact on the overall behaviour of TG cable bolt while the peak load of SuperStrand cable bolt was increased due to an increase in the diameter of borehole. Finally, from a comparative analysis, it was confirmed that TG cable bolt exhibits a higher load carrying capacity than Plain SuperStrand cable bolt

APPLICATION OF SPARSE GRID APPROACH TO HIGH DIMENSION OPTION PRICING PROBLEMS

Bachelor'sBACHELOR OF SCIENCE (HONOURS

Variation in anchorage performance of a high capacity modified bulb cable bolt under differing conditions in a weak confining medium

Cable bolts are increasingly being used for ground reinforcement due to their high load carrying capacity, tendon length and flexibility that affords easy installation. There are a variety of cable bolt designs on the market and while many have been tested, few studies have examined anchorage performance in a weak confining medium that approximates behaviour in coal. This paper presents the results of testing a high capacity cable bolt, the MW9 indented cable bolt, in weak material of differing borehole diameters and grout strengths. Both the standard recommended borehole diameter of 42 mm and an oversize borehole of 52 mm were examined in combination with the standard high strength grout strength of 80 MPa and a lower strength of 62 MPa. In weak grout, borehole diameter had minimal effect on the peak load carrying capacity with only a 6% reduction in capacity from an increase in borehole diameter from 42 mm to 52 mm. However, with the strong grout, there was a 7% increase in peak load carrying capacity with borehole diameter. In the standard borehole diameter, increasing grout strength reduced the peak load carrying capacity by 4% whereas there was a 10% in the oversized borehole. In the vast majority of tests, failure occurred at the bolt/grout interface