Gemini Planet Imager Observational Calibrations VI: Photometric and Spectroscopic Calibration for the Integral Field Spectrograph

The Gemini Planet Imager (GPI) is a new facility instrument for the Gemini Observatory designed to provide direct detection and characterization of planets and debris disks around stars in the solar neighborhood. In addition to its extreme adaptive optics and corona graphic systems which give access to high angular resolution and high-contrast imaging capabilities, GPI contains an integral field spectrograph providing low resolution spectroscopy across five bands between 0.95 and 2.5 $\mu$m. This paper describes the sequence of processing steps required for the spectro-photometric calibration of GPI science data, and the necessary calibration files. Based on calibration observations of the white dwarf HD 8049B we estimate that the systematic error in spectra extracted from GPI observations is less than 5%. The flux ratio of the occulted star and fiducial satellite spots within coronagraphic GPI observations, required to estimate the magnitude difference between a target and any resolved companions, was measured in the $H$-band to be $\Delta m = 9.23\pm0.06$ in laboratory measurements and $\Delta m = 9.39\pm 0.11$ using on-sky observations. Laboratory measurements for the $Y$, $J$, $K1$ and $K2$ filters are also presented. The total throughput of GPI, Gemini South and the atmosphere of the Earth was also measured in each photometric passband, with a typical throughput in $H$-band of 18% in the non-coronagraphic mode, with some variation observed over the six-month period for which observations were available. We also report ongoing development and improvement of the data cube extraction algorithm.Comment: 15 pages, 6 figures. Proceedings of the SPIE, 9147-30

Bringing "The Moth" to Light: A Planet-Sculpting Scenario for the HD 61005 Debris Disk

The HD 61005 debris disk ("The Moth") stands out from the growing collection of spatially resolved circumstellar disks by virtue of its unusual swept-back morphology, brightness asymmetries, and dust ring offset. Despite several suggestions for the physical mechanisms creating these features, no definitive answer has been found. In this work, we demonstrate the plausibility of a scenario in which the disk material is shaped dynamically by an eccentric, inclined planet. We present new Keck NIRC2 scattered-light angular differential imaging of the disk at 1.2-2.3 microns that further constrains its outer morphology (projected separations of 27-135 AU). We also present complementary Gemini Planet Imager 1.6 micron total intensity and polarized light detections that probe down to projected separations less than 10 AU. To test our planet-sculpting hypothesis, we employed secular perturbation theory to construct parent body and dust distributions that informed scattered-light models. We found that this method produced models with morphological and photometric features similar to those seen in the data, supporting the premise of a planet-perturbed disk. Briefly, our results indicate a disk parent body population with a semimajor axis of 40-52 AU and an interior planet with an eccentricity of at least 0.2. Many permutations of planet mass and semimajor axis are allowed, ranging from an Earth mass at 35 AU to a Jupiter mass at 5 AU.Comment: Accepted to AJ; added Figure 5 and minor text edit

Protein-tyrosine Phosphatase H1 Controls Growth Hormone Receptor Signaling and Systemic Growth

Several protein-tyrosine phosphatases (PTPs) have been implicated in the control of growth hormone receptor (GHR) signaling, but none have been shown to affect growth in vivo. We have applied a battery of molecular and cellular approaches to test a family-wide panel of PTPs for interference with GHR signaling. Among the subset of PTPs that showed activity in multiple readouts, we selected PTP-H1/PTPN3 for further in vivo studies and found that mice lacking the PTP-H1 catalytic domain show significantly enhanced growth over their wild type littermates. In addition, PTP-H1 mutant animals had enhanced plasma and liver mRNA expression of insulin-like growth factor 1, as well as increased bone density and mineral content. These observations point to a controlling role for PTP-H1 in modulating GHR signaling and systemic growth through insulin-like growth factor 1 secretion

Constraints on the architecture of the HD 95086 planetary system with the Gemini Planet Imager

We present astrometric monitoring of the young exoplanet HD 95086 b obtained with the Gemini Planet Imager between 2013 and 2016. A small but significant position angle change is detected at constant separation; the orbital motion is confirmed with literature measurements. Efficient Monte Carlo techniques place preliminary constraints on the orbital parameters of HD 95086 b. With 68% confidence, a semimajor axis of 61.7^{+20.7}_{-8.4} au and an inclination of 153.0^{+9.7}_{-13.5} deg are favored, with eccentricity less than 0.21. Under the assumption of a co-planar planet-disk system, the periastron of HD 95086 b is beyond 51 au with 68% confidence. Therefore HD 95086 b cannot carve the entire gap inferred from the measured infrared excess in the SED of HD 95086. We use our sensitivity to additional planets to discuss specific scenarios presented in the literature to explain the geometry of the debris belts. We suggest that either two planets on moderately eccentric orbits or three to four planets with inhomogeneous masses and orbital properties are possible. The sensitivity to additional planetary companions within the observations presented in this study can be used to help further constrain future dynamical simulations of the planet-disk system.Comment: Accepted for publication in ApJ

Relationships between big-five personality factors and Alzheimer\u27s disease pathology in autosomal dominant Alzheimer\u27s disease

Introduction: Changes in personality characteristics are associated with the onset of symptoms in Alzheimer\u27s disease (AD) and may even precede clinical diagnosis. However, personality changes caused by disease progression can be difficult to separate from changes that occur with normal aging. The Dominantly Inherited Alzheimer Network (DIAN) provides a unique cohort in which to relate measures of personality traits to in vivo markers of disease in a much younger sample than in typical late onset AD. Methods: Personality traits measured with the International Personality Item Pool at baseline from DIAN participants were analyzed as a function of estimated years to onset of clinical symptoms and well-established AD biomarkers. Results: Both neuroticism and conscientiousness were correlated with years to symptom onset and markers of tau pathology in the cerebrospinal fluid. Self-reported conscientiousness and both neuroticism and conscientiousness ratings from a collateral source were correlated with longitudinal rates of cognitive decline such that participants who were rated as higher on neuroticism and lower on conscientiousness exhibited accelerated rates of cognitive decline. Discussion: Personality traits are correlated with the accumulation of AD pathology and time to symptom onset, suggesting that AD progression can influence an individual\u27s personality characteristics. Together these findings suggest that measuring neuroticism and conscientiousness may hold utility in tracking disease progression in AD

Multimodal brain age estimates relate to Alzheimer disease biomarkers and cognition in early stages: A cross-sectional observational study

BACKGROUND: Estimates of \u27brain-predicted age\u27 quantify apparent brain age compared to normative trajectories of neuroimaging features. The brain age gap (BAG) between predicted and chronological age is elevated in symptomatic Alzheimer disease (AD) but has not been well explored in presymptomatic AD. Prior studies have typically modeled BAG with structural MRI, but more recently other modalities, including functional connectivity (FC) and multimodal MRI, have been explored. METHODS: We trained three models to predict age from FC, structural (S), or multimodal MRI (S+FC) in 390 amyloid-negative cognitively normal (CN/A-) participants (18-89 years old). In independent samples of 144 CN/A-, 154 CN/A+, and 154 cognitively impaired (CI; CDR \u3e 0) participants, we tested relationships between BAG and AD biomarkers of amyloid and tau, as well as a global cognitive composite. RESULTS: All models predicted age in the control training set, with the multimodal model outperforming the unimodal models. All three BAG estimates were significantly elevated in CI compared to controls. FC-BAG was significantly reduced in CN/A+ participants compared to CN/A-. In CI participants only, elevated S-BAG and S+FC BAG were associated with more advanced AD pathology and lower cognitive performance. CONCLUSIONS: Both FC-BAG and S-BAG are elevated in CI participants. However, FC and structural MRI also capture complementary signals. Specifically, FC-BAG may capture a unique biphasic response to presymptomatic AD pathology, while S-BAG may capture pathological progression and cognitive decline in the symptomatic stage. A multimodal age-prediction model improves sensitivity to healthy age differences. FUNDING: This work was supported by the National Institutes of Health (P01-AG026276, P01- AG03991, P30-AG066444, 5-R01-AG052550, 5-R01-AG057680, 1-R01-AG067505, 1S10RR022984-01A1, and U19-AG032438), the BrightFocus Foundation (A2022014F), and the Alzheimer\u27s Association (SG-20-690363-DIAN)

Gemini Planet Imager observational calibrations XV: instrument calibrations after six years on sky

The Gemini Planet Imager (GPI) is a high-contrast adaptive optics instrument designed to detect and characterize substellar companions and circumstellar debris disks around nearby young stars using infrared integral field spectroscopy and polarimetry. GPI has been in routine operations at Gemini South for the past six years. Because precise astrometry and photometry of exoplanets is critical to GPI's science, we undertook extensive efforts both in-lab and on-sky to refine the astrometric and photometric calibration of the instrument. We describe revisions to the GPI Data Reduction Pipeline (DRP) that account for these revised calibrations, and that fix several issues identified over the previous six years, including some subtle issues affecting astrometric calibrations caused by a drift of the instrument’s clock. These calibrations are critical for the interpretation of observations obtained with GPI, and for a comparison with measurements from other high-contrast imaging instruments

Gemini Planet Imager observational calibrations XV: instrument calibrations after six years on sky

The Gemini Planet Imager (GPI) is a high-contrast adaptive optics instrument designed to detect and characterize substellar companions and circumstellar debris disks around nearby young stars using infrared integral field spectroscopy and polarimetry. GPI has been in routine operations at Gemini South for the past six years. Because precise astrometry and photometry of exoplanets is critical to GPI's science, we undertook extensive efforts both in-lab and on-sky to refine the astrometric and photometric calibration of the instrument. We describe revisions to the GPI Data Reduction Pipeline (DRP) that account for these revised calibrations, and that fix several issues identified over the previous six years, including some subtle issues affecting astrometric calibrations caused by a drift of the instrument’s clock. These calibrations are critical for the interpretation of observations obtained with GPI, and for a comparison with measurements from other high-contrast imaging instruments

Longitudinal accumulation of cerebral microhemorrhages in dominantly inherited Alzheimer disease

OBJECTIVE: To investigate the inherent clinical risks associated with the presence of cerebral microhemorrhages (CMHs) or cerebral microbleeds and characterize individuals at high risk for developing hemorrhagic amyloid-related imaging abnormality (ARIA-H), we longitudinally evaluated families with dominantly inherited Alzheimer disease (DIAD). METHODS: Mutation carriers (n = 310) and noncarriers (n = 201) underwent neuroimaging, including gradient echo MRI sequences to detect CMHs, and neuropsychological and clinical assessments. Cross-sectional and longitudinal analyses evaluated relationships between CMHs and neuroimaging and clinical markers of disease. RESULTS: Three percent of noncarriers and 8% of carriers developed CMHs primarily located in lobar areas. Carriers with CMHs were older, had higher diastolic blood pressure and Hachinski ischemic scores, and more clinical, cognitive, and motor impairments than those without CMHs. CONCLUSION: Our study highlights factors associated with the development of CMHs in individuals with DIAD. CMHs are a part of the underlying disease process in DIAD and are significantly associated with dementia. This highlights that in participants in treatment trials exposed to drugs, which carry the risk of ARIA-H as a complication, it may be challenging to separate natural incidence of CMHs from drug-related CMHs