145 research outputs found
Estimation of fixed effects spatial dynamic panel data models with small T and unknown heteroskedasticity
Ministry of Education, Singapore under its Academic Research Funding Tier
Towards Code Watermarking with Dual-Channel Transformations
The expansion of the open source community and the rise of large language
models have raised ethical and security concerns on the distribution of source
code, such as misconduct on copyrighted code, distributions without proper
licenses, or misuse of the code for malicious purposes. Hence it is important
to track the ownership of source code, in wich watermarking is a major
technique. Yet, drastically different from natural languages, source code
watermarking requires far stricter and more complicated rules to ensure the
readability as well as the functionality of the source code. Hence we introduce
SrcMarker, a watermarking system to unobtrusively encode ID bitstrings into
source code, without affecting the usage and semantics of the code. To this
end, SrcMarker performs transformations on an AST-based intermediate
representation that enables unified transformations across different
programming languages. The core of the system utilizes learning-based embedding
and extraction modules to select rule-based transformations for watermarking.
In addition, a novel feature-approximation technique is designed to tackle the
inherent non-differentiability of rule selection, thus seamlessly integrating
the rule-based transformations and learning-based networks into an
interconnected system to enable end-to-end training. Extensive experiments
demonstrate the superiority of SrcMarker over existing methods in various
watermarking requirements.Comment: 16 page
Adjustment with Many Regressors Under Covariate-Adaptive Randomizations
Our paper discovers a new trade-off of using regression adjustments (RAs) in
causal inference under covariate-adaptive randomizations (CARs). On one hand,
RAs can improve the efficiency of causal estimators by incorporating
information from covariates that are not used in the randomization. On the
other hand, RAs can degrade estimation efficiency due to their estimation
errors, which are not asymptotically negligible when the number of regressors
is of the same order as the sample size. Ignoring the estimation errors of RAs
may result in serious over-rejection of causal inference under the null
hypothesis. To address the issue, we develop a unified inference theory for the
regression-adjusted average treatment effect (ATE) estimator under CARs. Our
theory has two key features: (1) it ensures the exact asymptotic size under the
null hypothesis, regardless of whether the number of covariates is fixed or
diverges no faster than the sample size; and (2) it guarantees weak efficiency
improvement over the ATE estimator without adjustments.Comment: 71 pages, including appendi
Spatial dynamic panel data models with correlated random effects
Ministry of Education, Singapore under its Academic Research Funding Tier
Time-series momentum: Is it there?
Ministry of Education, Singapore under its Academic Research Funding Tier
Indium Phosphide Bismide
Indium phosphide bismide is a new member to the dilute bismide family. Since the first synthesis by molecular beam epitaxy (MBE) in 2013, it has cut a figure for its abnormal properties comparing with other dilute bismides. Bismuth (Bi) incorporation is always a difficulty for epitaxial growth of dilute. In this chapter, it shows how to regulate MBE growth parameters and their influence on Bi incorporation in InP1−xBix. Structural, electronic and optical properties are systematically reviewed. Thermal annealing to study Bi thermal stability and its effect on physical properties is performed. InP1−xBix shows strong and broad photoluminescence at room temperature, which is a potential candidate for fabricating super-luminescence diodes applied for enhancing spatial resolution in optical coherence tomography. Quaternary phosphide bismide, including InGaPBi and InAlPBi, is briefly introduced in this chapter
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