Quantum optimization of maximum independent set using Rydberg atom arrays.

Realizing quantum speedup for practically relevant, computationally hard problems is a central challenge in quantum information science. Using Rydberg atom arrays with up to 289 qubits in two spatial dimensions, we experimentally investigate quantum algorithms for solving the maximum independent set problem. We use a hardware-efficient encoding associated with Rydberg blockade, realize closed-loop optimization to test several variational algorithms, and subsequently apply them to systematically explore a class of graphs with programmable connectivity. We find that the problem hardness is controlled by the solution degeneracy and number of local minima, and we experimentally benchmark the quantum algorithm's performance against classical simulated annealing. On the hardest graphs, we observe a superlinear quantum speedup in finding exact solutions in the deep circuit regime and analyze its origins.

Opposing actions of environmental enrichment and Alzheimer's disease on the expression of hippocampal microRNAs in mouse models.

Alzheimer's disease (AD) is the most common form of dementia in the elderly. Although there are no drugs that modify the disease process, exposure to an enriched environment (EE) can slow the disease progression. Here, we characterize the effects of AD and EE on the post-transcriptional regulators, microRNAs (miRNAs), which may contribute to the detrimental and beneficial effects of AD and EE, respectively, on synaptic plasticity-related proteins and AD pathology. We found for the first time miRNAs that were inversely regulated in AD and EE, and may affect synaptic proteins and modulators, molecular factors associated with AD pathology, and survival and neuroprotective factors. MiRNAs that were upregulated only in 3xTgAD mice model of AD compared with their control mice were localized to synapses, predicted to downregulate essential synaptic proteins and are highly associated with regulating apoptosis, AD-associated processes and axon guidance. Studying the progressive change in miRNAs modulation during aging of 3xTgAD mice, we identified miRNAs that were regulated in earlier stages of AD, suggesting them as potential AD biomarkers. Last, we characterized AD- and EE-related effects in the mouse hippocampus on tomosyn protein levels, an inhibitor of the synaptic transmission machinery. While EE reduced tomosyn levels, tomosyn levels were increased in old 3xTgAD mice, suggesting a role for tomosyn in the impairment of synaptic transmission in AD. Interestingly, we found that miR-325 regulates the expression levels of tomosyn as demonstrated by a luciferase reporter assay, and that miR-325 was downregulated in AD and upregulated following EE. These findings improve our understanding of the molecular and cellular processes in AD pathology, following EE, and the interplay between the two processes, and open new avenues for the studies of understanding and controlling AD.

A cross-cultural procedure to assess reliability and measurement invariance.

Steenkamp and Baumgartner (1998) developed a procedure to assess measurement invariance across cultures. The study presented here applied their procedure to a scale to measure cognitive age (Barak, 1979; 1987; 1998; Barak and Schiffman, 1981) and relied on data collected in three Non-Western societies: India (N=195), China (N=250), and Korea (N=251). The results from a series of confirmatory factor analyses indicate that the technique provides a valuable tool to assess measurement invariance across cultures. The results further showed the cognitive age scale to be applicable in the three diverse cultures surveyed.

Perceived youth: appraisal and characterization.

Results from a mail survey of respondents aged sixty to ninety-four suggest that psychographic dimensions of youthfulness and identification with old age constitute effective inner-age research variables, especially to those seeking to study older populations. The two specific dimensions explored are: "perceived youth," a magnitude measure of the proportional discrepancy between chronological and cognitive ages; and "feeling-old," which inversely measured youth through reliance on a six-point Likert agree/disagree statement: "I feel old...." In addition to the obvious inverse relationship between these inner-ages, research established trait covariation relative to an increase in perceived youth coincidental with a rejection of a feeling-old identity, corresponding to increases in "happiness, own-health rating, being venturesome, giving advice, self-esteem, social activity, and keeping-in-shape," as well as decreases in "taking advice, being a homebody, and having health worries."

Inner-ages of middle-aged prime-lifers.

A comprehensive survey examined three age-role self-concepts: cognitive, ideal, and social ages. Participants were forty to sixty-nine years old and viewed themselves as middle-aged. The investigation reviewed inner-age research and evaluated inner-age infra-structure (with t-tests and correlations), as well as connections between inner-age and participants' characteristics (with covariates, partial correlations, and regressions) in the context of eight psychographic trait-sets (sex-identity, quality-of-life, health, self-consciousness, societal traits, venturesomeness, supermarket shopping involvement, and exercise activities). The three inner ages, while closely interrelated diverged in their distribution patterns, in mean ages, as well as (after removal of birth age's linear effects) in their covariates and correlates.

Cognitive age: demographic and psychographic dimensions.

This empirical study, based on a random self-report mail survey, explored perceptions of age among mature Americans aged 60+. Respondents were members of a systematic probability sample located in the Mid Atlantic region. Two inner-age dimensions were considered: the first, Cognitive Age, is a measure of self-perceived age and assesses a person's "actual" age-role self-concept; the second, entitled Youthfulness, is a new measure of youth scored by what percentage a respondent's Age-of-Birth is greater than his or her Cognitive Age (Chronological Age/Cognitive Age). The study first explored the relationships between the age variables, and then, through Multivariate Analyses of Variance (MANOVAs), the associations between four trait-sets (demographics, health, Quality of Life, and psychographic traits) and the two inner-age dimensions.

Cognitive age: a new multidimensional approach to measuring age identity.

An exploratory field study was undertaken to explore the way in which age-concepts are experienced, and to assess the relationship of age identities to each other. In addition, this study seeks to establish a new multidimensional age scale, Cognitive Age, to replace the well-established standard scale, Identity Age. This research also functions as a follow-up to an exploration by Kastenbaum et al. of "ages-of-me." Ths most frequently used subjective age measures, Identity Age and Feel/Age, are unidimensional, and thus very difficult to evaluate in terms of reliability and/or validity. A multidimensional view of age as reflected by Personal Age is very appealing, but complex to assess. Cognitive Age successfully merges Identity Age, in which respondents identify with age-referrent groupings, and Personal Age, in which respondents rate themselves in terms of four functional age dimensions. The resultant Cognitive Age scale is both reliable and valid.