The Pseudosynchronization of Binary Stars Undergoing Strong Tidal Interactions

Eccentric binaries known as heartbeat stars experience strong dynamical tides as the stars pass through periastron, providing a laboratory to study tidal interactions. We measure the rotation periods of 24 heartbeat systems, using the Kepler light curves to identify rotation peaks in the Fourier transform. Where possible, we compare the rotation period to the pseudosynchronization period derived by Hut 1981. Few of our heartbeat stars are pseudosynchronized with the orbital period. For four systems, we were able to identify two sets of rotation peaks, which we interpret as the rotation from both stars in the binary. The majority of the systems have a rotation period that is approximately 3/2 times the pseudosynchronization period predicted by Hut 1981, suggesting that other physical mechanisms influence the stars' rotation, or that stars typically reach tidal spin equilibrium at a rotation period slightly longer than predicted.Comment: 9 pages, 4 figures, 1 table

Evidence That Luminant and Equiluminant Motion Signals Are Integrated by Directionally Selective Mechanisms

Three experiments tested whether motion information for nonequiluminant (luminant) and equiluminant dots affects direction judgments when both types of stimuli are moving simultaneously in the same display. The motion directions for the two sets of dots were manipulated to produce four direction differences (0°, 30°, 60°, and 90°). The equiluminant dots were moved in a perfectly correlated fashion, but the percentage of correlated motion for the luminant dots was varied. When subjects judged whether the directions of the equiluminant and luminant dots were the same or different, performance for the conditions with 0°, 60°, and 90° difference improved as the percentage of correlated luminant motion increased. The same result occurred for a control display that contained two sets of luminant dots. However, for the 30° difference, performance was at chance level for the control display, but dropped below chance for the equiluminant - luminant display. When subjects indicated just the direction of the luminant dots, judgments were not affected by equiluminant motion. Judgments for the equiluminant dots also were accurate, except for the conditions with 30° difference; these responses were biased by the luminant motion, indicating some form of motion capture. The interactive effects are discussed in terms of a directionally selective mechanism that combines equiluminant and luminant motion signals

New Constraints on the Timing and Pattern of Deglaciation in the Húnaflói Bay Region of Northwest Iceland Using Cosmogenic 36CA Dating and Geomorphic Mapping

Understanding the evolution and timing of changes in ice sheet geometry and extent in Iceland during the Last Glacial Maximum (LGM) and subsequent deglaciation continues to stimulate much active research. Though many previous studies have advanced our knowledge of Icelandic ice sheet history preserved in marine and terrestrial settings (e.g., Andrews et al., 2000; Norðdahl et al., 2008), the timing of ice margin retreat remains largely unknown in several key regions. Recently published 36Cl surface exposure ages of bedrock surfaces and moraines in the West Fjords (Brynjólfsson et al., 2015) contribute important progress in establishing more precise age control of ice recession in northwest Iceland. In another recent study, the spatial pattern and style of deglaciation in northern Iceland have been revealed through geomorphic mapping and GIS analyses of glacial landforms (Principato et al., 2016). Additional insight comes from updated numerical modeling reconstructions, which now provide a series of glaciologically plausible Icelandic ice sheet configurations from the LGM through the last deglaciation (Patton et al., 2017). However, the optimization of ice sheet model simulations relies on critical comparisons with the available empirical record of glacial-geologic evidence and chronological control, which remains relatively limited and sparsely distributed throughout Iceland. Our investigation is motivated by the need for more accurate constraints on the deglacial history in northern Iceland, where dated terrestrial records of ice margin retreat are particularly scarce. (excerpt

A persistent and dynamic East Greenland Ice Sheet over the past 7.5 million years

Climate models show that ice-sheet melt will dominate sea-level rise over the coming centuries, but our understanding of ice-sheet variations before the last interglacial 125,000 years ago remains fragmentary. This is because terrestrial deposits of ancient glacial and interglacial periods1,2,3 are overrun and eroded by more recent glacial advances, and are therefore usually rare, isolated and poorly dated4. In contrast, material shed almost continuously from continents is preserved as marine sediment that can be analysed to infer the time-varying state of major ice sheets. Here we show that the East Greenland Ice Sheet existed over the past 7.5 million years, as indicated by beryllium and aluminium isotopes (10Be and 26Al) in quartz sand removed by deep, ongoing glacial erosion on land and deposited offshore in the marine sedimentary record5,6. During the early Pleistocene epoch, ice cover in East Greenland was dynamic; in contrast, East Greenland was mostly ice-covered during the mid-to-late Pleistocene. The isotope record we present is consistent with distinct signatures of changes in ice sheet behaviour coincident with major climate transitions. Although our data are continuous, they are from low-deposition-rate sites and sourced only from East Greenland. Consequently, the signal of extensive deglaciation during short, intense interglacials could be missed or blurred, and we cannot distinguish between a remnant ice sheet in the East Greenland highlands and a diminished continent-wide ice sheet. A clearer constraint on the behaviour of the ice sheet during past and, ultimately, future interglacial warmth could be produced by 10Be and 26Al records from a coring site with a higher deposition rate. Nonetheless, our analysis challenges the possibility of complete and extended deglaciation over the past several million years

Sulforaphane Treatment of Children with Autism Spectrum Disorder – A Progress Report

This ongoing clinical trial in autism spectrum disorder (ASD) tests a nontoxic approach to therapy of ASD. Background: Direct treatment of underlying mechanisms in ASD is limited. Cellular dysfunction in ASD may involve a number of related metabolic pathways. The “fever effect” in ASD, in which febrile illness dramatically but temporarily ameliorates disordered behavior, offers a clinical clue. Fever stimulates heat shock proteins (HSP) and cellular stress responses that may ultimately lead to improved synaptic function and increased long-range connectivity. The expression of gene transcription by NFE2L2 (Nrf2), which is reduced in ASD, may also increase during fever. Sulforaphane (SF), an isothiocyanate obtained from 3-day-old broccoli sprouts, induces HSP and Nrf2 as well as “cell-protective” responses. SF has several possible modes of action that may benefit ASD through common cellular mechanisms underlying heterogeneous phenotypes. SF crosses the blood-brain barrier and is bioavailable orally. Preliminary data: In a randomized, double-blind, placebo-controlled pilot trial in 44 male adolescents and adults (13-30 years), results showed SF was well tolerated without significant side effects. On average, participants on SF (particularly those with a history of fever effect) showed significantly more improvements in ASD symptoms – including social interaction, aberrant/abnormal behavior, repetitive/stereotypical behavior, and verbal communication – than placebo participants. Current study: Our randomized, double-blind, placebo-controlled phase-2 clinical trial at UMass has three aims: To determine: (1) if orally administered SF has measurable effects in children (ages 3-12 years) with ASD; (2) if treatment with sulforaphane is safe and well tolerated; (3) To elucidate cellular biomarkers that support the mechanisms of action of SF in ASD. We hypothesize that positive effects of SF will be more marked and lasting in the developing brain. To date, 7 participants have completed the trial, and 22 are actively enrolled. Recruitment is ongoing, with a target sample size of 50

Sulforaphane Treatment of Children with Autism Spectrum Disorder

Abstract This clinical trial in autism spectrum disorder (ASD) tests a nontoxic approach to therapy of ASD. Background: Direct treatment of underlying mechanisms in ASD is limited. Cellular dysfunction in ASD may involve a number of related metabolic pathways. A clinical clue may be found in the “fever effect” in ASD, in which febrile illness dramatically but temporarily ameliorates disordered behavior. Fever stimulates heat shock proteins (HSP) and cellular stress responses that may ultimately lead to improved synaptic function and increased long-range connectivity. The expression of gene transcription by NFE2L2 (Nrf2), which is reduced in ASD, may also increase during fever. Sulforaphane (SF), an isothiocyanate obtained from 3-day-old broccoli sprouts, induces HSP and Nrf2 as well as “cell-protective” responses. SF has several possible modes of action that may benefit ASD through common cellular mechanisms underlying heterogeneous phenotypes. SF crosses the blood brain barrier and is bioavailable orally. Preliminary data: In a randomized, double-blind, placebo-controlled pilot trial in 44 male adolescents and adults (13-30 years), results showed SF was well tolerated without significant side effects. On average, participants on SF (particularly those with a history of fever effect) showed significantly more improvements in ASD symptoms than placebo participants. Significant improvements for SF participants included social interaction, aberrant/abnormal behavior, repetitive/stereotypical behavior, and verbal communication. Current study: Our randomized, double-blind, placebo-controlled phase-2 clinical trial at UMass has three aims: To determine: (1) if orally administered SF has measurable effects in children (ages 3-12 years) with ASD; (2) if treatment with sulforaphane is safe and well tolerated; (3) To elucidate cellular biomarkers that support the mechanisms of action of SF in ASD. We hypothesize that SF will have positive effects, and that these effects will be more marked and lasting in the developing – compared to the mature – brain

Children's Understanding of Psychogenic Bodily Reactions

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65537/1/1467-8624.00289.pd