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1. Analytical gradients and derivative couplings for the TDDFT-1D method

   https://doi.org/10.1063/5.0130404  

   Athavale, Vishikh; Teh, Hung-Hsuan; Shao, Yihan; Subotnik, Joseph (December 2022, The Journal of Chemical Physics)

   We derive and implement analytic gradients and derivative couplings for time-dependent density functional theory plus one double (TDDFT-1D) which is a semiempirical configuration interaction method whereby the Hamiltonian is diagonalized in a basis of all singly excited configurations and one doubly excited configuration as constructed from a set of reference Kohn–Sham orbitals. We validate the implementation by comparing against finite difference values. Furthermore, we show that our implementation can locate both optimized geometries and minimum-energy crossing points along conical seams of S1/S0 surfaces for a set of test cases. 

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2. Maximizing Patch Coverage for Testing of Highly-Configurable Software without Exploding Build Times

   https://doi.org/10.1145/3643746  

   Yıldıran, Necip Fazıl; Oh, Jeho; Lawall, Julia; Gazzillo, Paul (July 2024, Proceedings of the ACM on Software Engineering)

   The Linux kernel is highly-configurable, with a build system that takes a configuration file as input and automatically tailors the source code accordingly. Configurability, however, complicates testing, because different configuration options lead to the inclusion of different code fragments. With thousands of patches received per month, Linux kernel maintainers employ extensive automated continuous integration testing. To attempt patch coverage, i.e., taking all changed lines into account, current approaches either use configuration files that maximize total statement coverage or use multiple randomly-generated configuration files, both of which incur high build times without guaranteeing patch coverage. To achieve patch coverage without exploding build times, we propose krepair, which automatically repairs configuration files that are fast-building but have poor patch coverage to achieve high patch coverage with little effect on build times. krepair works by discovering a small set of changes to a configuration file that will ensure patch coverage, preserving most of the original configuration file's settings. Our evaluation shows that, when applied to configuration files with poor patch coverage on a statistically-significant sample of recent Linux kernel patches, krepair achieves nearly complete patch coverage, 98.5% on average, while changing less than 1.53% of the original default configuration file in 99% of patches, which keeps build times 10.5x faster than maximal configuration files. 

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3. Positive Configuration Space

   https://doi.org/10.1007/s00220-021-04041-x  

   Arkani-Hamed, Nima; Lam, Thomas; Spradlin, Marcus (April 2021, Communications in Mathematical Physics)

   Abstract We define and study the totally nonnegative part of the Chow quotient of the Grassmannian, or more simply thenonnegative configuration space. This space has a natural stratification bypositive Chow cells, and we show that nonnegative configuration space is homeomorphic to a polytope as a stratified space. We establish bijections between positive Chow cells and the following sets: (a) regular subdivisions of the hypersimplex into positroid polytopes, (b) the set of cones in the positive tropical Grassmannian, and (c) the set of cones in the positive Dressian. Our work is motivated by connections to super Yang–Mills scattering amplitudes, which will be discussed in a sequel. 

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4. Performance Health Index for Complex Cyber Infrastructures

   https://doi.org/10.1145/3538646  

   Sondur, Sanjeev; Kant, Krishna (March 2022, ACM Transactions on Modeling and Performance Evaluation of Computing Systems)

   Most IT systems depend on a set of configuration variables (CVs) , expressed as a name/value pair that collectively defines the resource allocation for the system. While the ill effects of misconfiguration or improper resource allocation are well-known, there are no effective a priori metrics to quantify the impact of the configuration on the desired system attributes such as performance, availability, etc. In this paper, we propose a Configuration Health Index (CHI) framework specifically attuned to the performance attribute to capture the influence of CVs on the performance aspects of the system. We show how CHI , which is defined as a configuration scoring system, can take advantage of the domain knowledge and the available (but rather limited) performance data to produce important insights into the configuration settings. We compare the CHI with both well-advertised segmented non-linear models and state-of-the-art data-driven models, and show that the CHI not only consistently provides better results but also avoids the dangers of a pure data drive approach which may predict incorrect behavior or eliminate some essential configuration variables from consideration. 

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5. No explicit memory for individual trial display configurations in a visual search task

   https://doi.org/10.3758/s13421-021-01185-y  

   O’Donnell, Ryan E.; Chen, Hui; Wyble, Brad (April 2021, Memory & Cognition)

   null (Ed.)

   Previous evidence demonstrated that individuals can recall a target’s location in a search display even if location information is completely task-irrelevant. This finding raises the question: does this ability to automatically encode a single item’s location into a reportable memory trace extend to other aspects of spatial information as well? We tested this question using a paradigm designed to elicit attribute amnesia (Chen & Wyble, 2015a). Participants were initially asked to report the location of a target letter among digits with stimuli arranged to form one of two or four spatial configurations varying randomly across trials. After completing numerous trials that matched their expectations, participants were surprised with a series of unexpected questions probing their memory for various aspects of the display they had just viewed. Participants had a profound inability to report which spatial configuration they had just perceived when the target’s location was not unique to a specific configuration (i.e., orthogonal). Despite being unable to report the most recent configuration, answer choices on the surprise trial were focused around previously seen configurations, rather than novel configurations. Thus, there were clear memories of the set of configurations that had been viewed during the experiment but not of the specific configuration from the most recent trial. This finding helps to set boundary conditions on previous findings regarding the automatic encoding of location information into memory. 

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