Miracle-dz/UniFAR-FTUs huggingface dataset:
Linear Stochastic Approximation: How Far Does Constant Step-Size and Iterate Averaging Go?

In this paper we study study constant stepsize averaged linear stochastic approximation. With an eye towards linear value estimation in reinforcement learning, we ask whether for a given class of linear estimation problems i) a single universal constant stepsize with ii) a C/t worst-case expected error with a class-dependent constant C > 0 can be guaranteed when the error is measured via an appropriate weighted squared norm. Such a result has recently been obtained in the context of linear least squares regression. We give examples that show that the answer to these questions in general is no. On the positive side, we also characterize the instance dependent behavior of the error of the said algorithms, identify some conditions under which the answer to the above questions can be changed to the positive, and in particular show instance-dependent error bounds of magnitude O(1/t) for the constant stepsize iterate averaged versions of TD(0) and a novel variant of GTD, where the stepsize is chosen independently of the value estimation instance. Computer simulations are used to illustrate and complement the theory.
A chatbot using LSTM-based multi-layer embedding for elderly care

According to demographic changes, the services designed for the elderly are becoming more needed than before and increasingly important. In previous work, social media or community-based question-answer data were generally used to build the chatbot. In this study, we collected the MHMC chitchat dataset from daily conversations with the elderly. Since people are free to say anything to the system, the collected sentences are converted into patterns in the preprocessing part to cover the variability of conversational sentences. Then, an LSTM-based multi-layer embedding model is used to extract the semantic information between words and sentences in a single turn with multiple sentences when chatting with the elderly. Finally, the Euclidean distance is employed to select a proper question pattern, which is further used to select the corresponding answer to respond to the elderly. For performance evaluation, five-fold cross-validation scheme was employed for training and evaluation. Experimental results show that the proposed method achieved an accuracy of 79.96% for top-1 response selection, which outperformed the traditional Okapi model.
Nasal obstruction during adolescence induces memory/learning impairments associated with BDNF/TrkB signaling pathway hypofunction and high corticosterone levels

The hippocampus is an important brain region involved in memory and learning. Brain‐derived neurotrophic factor (BDNF), tyrosine kinase receptor B (TrkB), and phospho‐p44/p42 mitogen‐activated protein kinase (MAPK) are known to contribute to hippocampal memory/learning. The present study aimed to clarify the effects of nasal obstruction during the growth period on memory/learning in an animal model, using combined behavioral, biochemical, and histological approaches. Male BALB/C mice underwent unilateral nasal obstruction (UNO) by cauterization at 8 days of age and were subjected to Y‐maze and passive avoidance tests at 15 weeks of age. The serum corticosterone levels were measured using an enzyme‐linked immunosorbent assay, and brain tissues were subjected to hematoxylin‐eosin staining and histological analysis or homogenization and Western blot analysis. Compared with control mice, UNO mice had lower blood oxygen saturation levels and exhibited apparent memory/learning impairments during behavioral testing. Additionally, the UNO group had higher hippocampal BDNF levels and serum corticosterone levels, lower hippocampal TrkB and phospho‐p44/p42 MAPK levels, and reduced neuron numbers relative to controls. Our findings suggest that UNO during adolescence affects the hippocampus and causes memory/learning impairments.
Quantum SDP Solvers: Large Speed-Ups, Optimality, and Applications to Quantum Learning

We give two quantum algorithms for solving semidefinite programs (SDPs) providing quantum speed-ups. We consider SDP instances with $m$ constraint matrices, each of dimension $n$, rank at most $r$, and sparsity $s$. The first algorithm assumes access to an oracle to the matrices at unit cost. We show that it has run time $\tilde{O}(s^2(\sqrt{m}\epsilon^{-10}+\sqrt{n}\epsilon^{-12}))$, with $\epsilon$ the error of the solution. This gives an optimal dependence in terms of $m, n$ and quadratic improvement over previous quantum algorithms when $m\approx n$. The second algorithm assumes a fully quantum input model in which the matrices are given as quantum states. We show that its run time is $\tilde{O}(\sqrt{m}+\text{poly}(r))\cdot\text{poly}(\log m,\log n,B,\epsilon^{-1})$, with $B$ an upper bound on the trace-norm of all input matrices. In particular the complexity depends only poly-logarithmically in $n$ and polynomially in $r$. We apply the second SDP solver to learn a good description of a quantum state with respect to a set of measurements: Given $m$ measurements and a supply of copies of an unknown state $\rho$ with rank at most $r$, we show we can find in time $\sqrt{m}\cdot\text{poly}(\log m,\log n,r,\epsilon^{-1})$ a description of the state as a quantum circuit preparing a density matrix which has the same expectation values as $\rho$ on the $m$ measurements, up to error $\epsilon$. The density matrix obtained is an approximation to the maximum entropy state consistent with the measurement data considered in Jaynes' principle from statistical mechanics. As in previous work, we obtain our algorithm by "quantizing" classical SDP solvers based on the matrix multiplicative weight method. One of our main technical contributions is a quantum Gibbs state sampler for low-rank Hamiltonians with a poly-logarithmic dependence on its dimension, which could be of independent interest.
ARMS2 variants may predict the 3-year outcome of photodynamic therapy for wet age-related macular degeneration

Purpose To determine the association of age-related maculopathy susceptibility 2 (ARMS2) gene polymorphisms with the 3-year outcomes of photodynamic therapy (PDT) in wet age-related macular degeneration (wet AMD). Methods The single nucleotide polymorphism (SNP) at rs10490924 in the ARMS2 gene of 65 patients with wet AMD who underwent PDT was genotyped using the TaqMan assay. The clinical characteristics and the outcomes of PDT were compared among the three genotypes at rs10490924. A multivariate regression analysis was performed to evaluate the influence of the clinical cofactors on the association of rs10490924 with the visual outcome at 36 months after the first PDT. Results A significant difference was found among the genotypes in the age and the baseline lesion size. The patients with the GG genotype showed a significant improvement in vision, and the patients with the TT genotype showed a significant worsening of vision at all time points measured after the initial PDT. In the multivariate regression analysis, the number of the G allele at rs10490924 was associated with a significantly greater improvement in the baseline best-corrected visual acuity (BCVA) at 36 months after the first PDT. Conclusions ARMS2 variants are likely associated with the 3-year outcomes of PDT in patients with wet AMD.
Influence of current input-output and age of first exposure on phonological acquisition in early bilingual Spanish-English-speaking kindergarteners.

BACKGROUND Although some investigations of phonological development have found that segmental accuracy is comparable in monolingual children and their bilingual peers, there is evidence that language use affects segmental accuracy in both languages. AIMS To investigate the influence of age of first exposure to English and the amount of current input-output on phonological accuracy in English and Spanish in early bilingual Spanish-English kindergarteners. Also whether parent and teacher ratings of the children's intelligibility are correlated with phonological accuracy and the amount of experience with each language. METHODS & PROCEDURES Data for 91 kindergarteners (mean age = 5;6 years) were selected from a larger dataset focusing on Spanish-English bilingual language development. All children were from Central Texas, spoke a Mexican Spanish dialect and were learning American English. Children completed a single-word phonological assessment with separate forms for English and Spanish. The assessment was analyzed for segmental accuracy: percentage of consonants and vowels correct and percentage of early-, middle- and late-developing (EML) sounds correct were calculated. OUTCOMES & RESULTS Children were more accurate on vowel production than consonant production and showed a decrease in accuracy from early to middle to late sounds. The amount of current input-output explained more of the variance in phonological accuracy than age of first English exposure. Although greater current input-output of a language was associated with greater accuracy in that language, English-dominant children were only significantly more accurate in English than Spanish on late sounds, whereas Spanish-dominant children were only significantly more accurate in Spanish than English on early sounds. Higher parent and teacher ratings of intelligibility in Spanish were correlated with greater consonant accuracy in Spanish, but the same did not hold for English. Higher intelligibility ratings in English were correlated with greater current English input-output, and the same held for Spanish. CONCLUSIONS & IMPLICATIONS Current input-output appears to be a better predictor of phonological accuracy than age of first English exposure for early bilinguals, consistent with findings on the effect of language experience on performance in other language domains in bilingual children. Although greater current input-output in a language predicts higher accuracy in that language, this interacts with sound complexity. The results highlight the utility of the EML classification in assessing bilingual children's phonology. The relationships of intelligibility ratings with current input-output and sound accuracy can shed light on the process of referral of bilingual children for speech and language services.
Comparative Evaluation of Methodologies for T-Wave Alternans Mapping in Electrograms

Electrograms (EGM) recorded from the surface of the myocardium are becoming more and more accessible. T-wave alternans (TWA) is associated with increased vulnerability to ventricular tachycardia/fibrillation and it occurs before the onset of ventricular arrhythmias. Thus, accurate methodologies for time-varying alternans estimation/detection in EGM are needed. In this paper, we perform a simulation study based on epicardial EGM recorded in vivo in humans to compare the accuracy of four methodologies: the spectral method (SM), modified moving average method, laplacian likelihood ratio method (LLR), and a novel method based on time-frequency distributions. A variety of effects are considered, which include the presence of wide band noise, respiration, and impulse artifacts. We found that 1) EGM-TWA can be detected accurately when the standard deviation of wide-band noise is equal or smaller than ten times the magnitude of EGM-TWA. 2) Respiration can be critical for EGM-TWA analysis, even at typical respiratory rates. 3) Impulse noise strongly reduces the accuracy of all methods, except LLR. 4) If depolarization time is used as a fiducial point, the localization of the T-wave is not critical for the accuracy of EGM-TWA detection. 5) According to this study, all methodologies provided accurate EGM-TWA detection/quantification in ideal conditions, while LLR was the most robust, providing better detection-rates in noisy conditions. Application on epicardial mapping of the in vivo human heart shows that EGM-TWA has heterogeneous spatio-temporal distribution.
The requirement of BDNF for hippocampal synaptic plasticity is experience‐dependent

Brain‐derived neurotrophic factor (BDNF) supports neuronal survival, growth, and differentiation and has been implicated in forms of hippocampus‐dependent learning. In vitro, a specific role in hippocampal synaptic plasticity has been described, although not all experience‐dependent forms of synaptic plasticity critically depend on BDNF. Synaptic plasticity is likely to enable long‐term synaptic information storage and memory, and the induction of persistent (>24 h) forms, such as long‐term potentiation (LTP) and long‐term depression (LTD) is tightly associated with learning specific aspects of a spatial representation. Whether BDNF is required for persistent (>24 h) forms of LTP and LTD, and how it contributes to synaptic plasticity in the freely behaving rodent has never been explored. We examined LTP, LTD, and related forms of learning in the CA1 region of freely dependent mice that have a partial knockdown of BDNF (BDNF+/−). We show that whereas early‐LTD (<90min) requires BDNF, short‐term depression (<45 min) does not. Furthermore, BDNF is required for LTP that is induced by mild, but not strong short afferent stimulation protocols. Object‐place learning triggers LTD in the CA1 region of mice. We observed that object‐place memory was impaired and the object‐place exploration failed to induce LTD in BDNF+/− mice. Furthermore, spatial reference memory, that is believed to be enabled by LTP, was also impaired. Taken together, these data indicate that BDNF is required for specific, but not all, forms of hippocampal‐dependent information storage and memory. Thus, very robust forms of synaptic plasticity may circumvent the need for BDNF, rather it may play a specific role in the optimization of weaker forms of plasticity. The finding that both learning‐facilitated LTD and spatial reference memory are both impaired in BDNF+/− mice, suggests moreover, that it is critically required for the physiological encoding of hippocampus‐dependent memory. © 2015 The Authors Hippocampus Published by Wiley Periodicals, Inc.
Infaunal Benthic Communities from the Inner Shelf off Southwestern Africa Are Characterised by Generalist Species

Infaunal communities of benthic macro-organisms (≥ 1mm length) were studied from 81 samples collected across nine sites to the north and south of the Orange River in the Benguela upwelling ecosystem in 2003, with a view to describing communities and understanding the drivers of regional community structure, as well as to document diversity and to examine geographic affinities. Although the fauna was dominated by polychaetes and peracarid crustaceans, patterns in community structure could only weakly be explained by the measured environment (~35%). This is attributed to the generalist nature of the species recovered, which were widely distributed amongst different sediments, water-depths and latitudes. The fauna is dominated by species that enjoy a widespread regional and global distribution and is characterised by relatively low diversity, which is discussed.
Association between vitamin B12-containing supplement consumption and prevalence of biochemically defined B12 deficiency in adults in NHANES III (Third National Health and Nutrition Examination Survey)

Abstract Objective To explore the association between vitamin B12 (B12)-containing supplement use, low B12 concentrations and biochemically defined B12 deficiency in US adults. Design A cross-sectional study with adjustment for survey design. Prevalence ratios for two age groups (18–50 and >50 years) were estimated using unconditional logistic models. Outcome measures included prevalence of low serum B12 concentration (<148 pmol/l) and biochemical B12 deficiency (serum B12 < 148 pmol/l with concomitant homocysteine > 10 μmol/l). Setting A population survey of health and nutritional measures. Subjects Subjects were non-institutionalized adults, aged 18 years and older, who participated in Phase 2 of NHANES III (Third National Health and Nutrition Examination Survey). Results Low B12 concentrations were less prevalent among persons consuming B12-containing supplements (P = 0·001) with an adjusted prevalence ratio of 0·6 (95 % CI 0·3, 1·0). Biochemical B12 deficiency showed a similar trend (P = 0·0002), with an adjusted prevalence ratio of 0·3 (95 % CI 0·1, 0·8). Prevalence ratios were similar in adults >50 years of age, although the prevalence of low B12 and biochemical deficiency was proportionally higher. Conclusions Consumption of B12-containing supplements was associated with at least 50 % lower prevalence of both low serum B12 and biochemical B12 deficiency in a nationally representative sample of US adults, suggesting increased consumption of B12 from supplements or from fortified foods may reduce the prevalence of B12 deficiency. Additionally, the current Recommended Daily Allowance for B12 of 2·4 μg may be insufficient for those aged >50 years.
Nonlinear Structured Signal Estimation in High Dimensions via Iterative Hard Thresholding

We study the high-dimensional signal estimation problem with nonlinear measurements, where the signal of interest is either sparse or low-rank. In both settings, our estimator is formulated as the minimizer of the nonlinear least-squares loss function under a combinatorial constraint, which is obtained efficiently by the iterative hard thresholding (IHT) algorithm. Although the loss function is nonconvex due to the nonlinearity of the statistical model, the IHT algorithm is shown to converge linearly to a point with optimal statistical accuracy using arbitrary initialization. Moreover, our analysis only hinges on conditions similar to those required in the linear case. Detailed numerical experiments are included to corroborate the theoretical results.
The Impact of Introductory Incentives on New Users: Evidence from an Online Health Community

Many online communities now employ introductory incentives to attract new users and motivate user contributions, but the benefit of such incentives is still unclear. We draw on a policy change in a large online health community to explore the impact of short-term introductory incentives. We find that even though introductory incentives increase contribution quantity during the policy window, such incentives can significantly decrease it after the policy. The policy also harms the community by lowering contribution quality. However, introductory incentives can increase user retention and thus induce more contribution over the lifecycle of users. Moreover, the effects of such incentives are contingent on users’ offline seniority, which creates opportunities for the platform to target different user groups. This research contributes to the literature on identifying the impact of introductory incentives and intertemporal change of monetary incentives in online communities. The findings also provide novel insights for incentive-driven online communities.
Myopia and Anchoring George-Marios Angeletos

We consider a stationary setting featuring forward-looking behavior, slow learning, and higherorder uncertainty. We obtain an observational equivalence result that recasts the aggregate dynamics of this setting as that of a representative-agent model featuring two distortions: myopia in the sense of extra discounting of the future; and anchoring of the current outcome to the past outcome, as in models that feature consumption habit, adjustment costs to investment, or past-price indexation. This builds a bridge to the DSGE literature; it also distinguishes our approach from an emerging literature on bounded rationality that captures the first feature (myopia) but misses the second feature (anchoring). We further show that the as-if distortions are larger when the generalequilibrium interaction is stronger; this property reflects the role of higher-order uncertainty and helps reduce the gap between macroeconomic and microeconomic estimates of adjustment frictions. We finally illustrate the quantitative potential of our theory in the context of inflation by showing how it can help rationalize existing estimates of the Hybrid NKPC while also matching survey evidence on expectations. MIT and NBER; angelet@mit.edu. Yale University; zhen.huo@yale.edu.
Heat Transport at Solid-Liquid Interfaces between Face-Centered Cubic Lattice and Liquid Alkanes

Article history: Received 20 March 2018 Received in revised form 6 April 2018 Accepted 22 April 2018 Available online 30 April 2018 Solid-liquid (S-L) interfaces is widely used in lubrication and coating systems, in which the heat transport is the main problem for the system. In the recent years, lubrication and coating systems have been investigated up to the molecular scale to solve the problem of heat transport due to wear and friction. In molecular scale, the characteristics of heat transport are different from the conventional one. Therefore, the purpose of this study is to specifically investigate the characteristics of heat transport in the molecular scale at the S-L interfaces. The prime concern in this numerical investigation is the surface structure of solid and the type of liquid molecules. The characteristics of heat transport at the S-L interfaces are evaluated based on the temperature jump (TJ) and thermal boundary resistance (TBR) at the interfaces. It is found that the different TJs and TBRs can be observed for variation of the surface structures and the length of liquid molecules. The obtained results show that the surface structures and length of liquid molecules significantly affect the characteristics of heat transport at S-L interfaces.
Live-Attenuated Respiratory Syncytial Virus Vaccine Candidate With Deletion of RNA Synthesis Regulatory Protein M2-2 is Highly Immunogenic in Children

Background Live respiratory syncytial virus (RSV) candidate vaccine LIDΔM2-2 is attenuated by deletion of the RSV RNA regulatory protein M2-2, resulting in upregulated viral gene transcription and antigen expression but reduced RNA replication. Methods RSV-seronegative children ages 6-24 months received a single intranasal dose of 105 plaque forming units (PFU) of LIDΔM2-2 (n = 20) or placebo (n = 9) (NCT02237209, NCT02040831). RSV serum antibodies, vaccine infectivity, and reactogenicity were assessed. During the following RSV season, participants were monitored for respiratory illness and pre- and post-RSV season serum antibodies. Results Vaccine virus was shed by 95% of vaccinees (median peak titers of 3.8 log10 PFU/mL by quantitative culture and 6.3 log10 copies/mL by PCR); 90% had ≥4-fold rise in serum neutralizing antibodies. Respiratory symptoms and fever were common in vaccine (95%) and placebo (78%). One vaccinee had grade 2 rhonchi concurrent with vaccine shedding, rhinovirus, and enterovirus. Eight of 19 vaccinees versus 2 of 9 placebo recipients had substantially increased RSV antibody titers after the RSV season without medically attended RSV disease, indicating anamnestic vaccine responses to wild-type RSV without significant illness. Conclusion LIDΔM2-2 had excellent infectivity and immunogenicity, encouraging further study of vaccine candidates attenuated by M2-2 deletion. Clinical Trials Registration NCT02237209, NCT02040831.
Adaptive balancing of gradient and update computation times using global geometry and approximate subproblems

First-order optimization methods comprise two important primitives: i) the computation of gradient information and ii) the computation of the update that leads to the next iterate. In practice there is often a wide mismatch between the time required for the two steps, leading to underutilization of resources. In this work, we propose a new framework, Approx Composite Minimization (ACM) that uses approximate update steps to ensure balance between the two operations. The accuracy is adaptively chosen in an online fashion to take advantage of changing conditions. Our unified analysis for approximate composite minimization generalizes and extends previous work to new settings. Numerical experiments on Lasso regression and SVMs demonstrate the effectiveness of the novel scheme.