Localization-dependent charge separation efficiency at an organic/inorganic hybrid interface

By combining complementary optical techniques, photoluminescence and time-resolved excited state absorption, we achieve a comprehensive picture of the relaxation processes in the organic/inorganic hybrid system SP6/ZnO. We identify two long-lived excited states of the organic molecules of which only the lowest energy one, localized on the sexiphenyl backbone of the molecule, is found to efficiently charge separate to the ZnO conduction band or radiatively recombine. The other state, most likely localized on the spiro-linked biphenyl, relaxes only by intersystem crossing to a long-lived, probably triplet state, thus acting as a sink of the excitation and limiting the charge separation efficiency.Comment: 6 pages, 5 figure

Robust Change-Point Detection for Functional Time Series Based on UU-Statistics and Dependent Wild Bootstrap

The aim of this paper is to develop a change-point test for functional time series that uses the full functional information and is less sensitive to outliers compared to the classical CUSUM test. For this aim, the Wilcoxon two-sample test is generalized to functional data. To obtain the asymptotic distribution of the test statistic, we proof a limit theorem for a process of $U$-statistics with values in a Hilbert space under weak dependence. Critical values can be obtained by a newly developed version of the dependent wild bootstrap for non-degenerate 2-sample $U$-statistics

Decomposing Counterfactual Explanations for Consequential Decision Making

The goal of algorithmic recourse is to reverse unfavorable decisions (e.g., from loan denial to approval) under automated decision making by suggesting actionable feature changes (e.g., reduce the number of credit cards). To generate low-cost recourse the majority of methods work under the assumption that the features are independently manipulable (IMF). To address the feature dependency issue the recourse problem is usually studied through the causal recourse paradigm. However, it is well known that strong assumptions, as encoded in causal models and structural equations, hinder the applicability of these methods in complex domains where causal dependency structures are ambiguous. In this work, we develop \texttt{DEAR} (DisEntangling Algorithmic Recourse), a novel and practical recourse framework that bridges the gap between the IMF and the strong causal assumptions. \texttt{DEAR} generates recourses by disentangling the latent representation of co-varying features from a subset of promising recourse features to capture the main practical recourse desiderata. Our experiments on real-world data corroborate our theoretically motivated recourse model and highlight our framework's ability to provide reliable, low-cost recourse in the presence of feature dependencies

CONTRASTING TOP-DOWN AND BOTTOM-UP RETRIEVAL METHODS FOR ASSESSING AUTOBIOGRAPHICAL MEMORY

Autobiographical memory (AM) is a unique type of memory for storing personally relevant information. AM specificity has been linked to a variety of psychological functions and mental health outcomes. Researchers have relied on two approaches to measure AM specificity: generative retrieval, wherein individuals are cued to initiate a top-down search for a memory, and direct retrieval, wherein a highly specific cue induces bottom-up activation of a memory. AM has almost always been assessed via generative retrieval measures, which fail to fully measure AM access as they exclude instances of bottom-up AM retrieval. Consequently, generative retrieval measures may confound AM specificity with executive functioning because generative retrieval engages working memory to a greater extent than direct retrieval. This study compared direct retrieval (odor-elicited) and generative retrieval (sentence-completion) measures of AM access and contrasted working memory’s association with both types of retrieval in 87 community-dwelling adult smokers. Analyses revealed no correlation between generative and direct retrieval measures. In addition, neither type of retrieval was significantly associated with working memory capacity. Concerns about measurement validity for the study sample limited the conclusions that could be drawn from the data, but highlighted the need for increased prudence when selecting memory measures. Future work using a broad and multimodal approach to AM assessment should continue to investigate the relationship between top-down and bottom-up approaches to measuring AM access, as this holds promise for understanding AM structure and its relation to a host of psychologically meaningful constructs

AN FMRI STUDY OF THE IMPACT OF OLFACTORY CUES ON CIGARETTE CRAVING

Cigarette smoking remains the number one preventable cause of death in the United States. Cigarette craving during a quit attempt has been linked to relapse, suggesting it is a clinically significant construct. This study investigated an understudied method of craving reduction, involving the administration of olfactory cues after craving induction. Olfactory cues may work to combat craving because they strongly engage attentional and emotional processing, can induce vivid autobiographical memory (AM) recall, and because olfactory processing brain regions overlap with regions involved in craving. Using both general linear model (GLM) and multivoxel pattern analysis (MVPA) approaches, this study collected fMRI and behavioral data to build upon a set of behavioral studies that have found odors to be an effective craving reduction tool. The neural response during a strong craving state was assessed in 39 adult daily smokers across a variety of craving, olfactory, and AM regions before and after an odor exposure paradigm, during which half of the participants smelled a pleasant odor cue and half smelled a neutral odor. Results indicate that exposure to a pleasant odor cue (compared to a neutral odor cue) changed the neural response in craving related regions. Odor characteristics, namely specific memory association for an odor, and individual differences in attention to odors were found to influence this odor-induced craving change. In addition, this study found that MVPA techniques are compatible with the unique study design requirements of craving research. Study limitations, implications, and possible future directions are discussed in light of these findings