Optical Comb Generation for Streak Camera Calibration for Inertial Confinement Fusion Experiments

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is coming on-line to support physics experimentation for the U.S. Department of Energy (DOE) programs in Inertial Confinement Fusion (ICF) and Stockpile Stewardship (SS). Optical streak cameras are an integral part of the experimental diagnostics instrumentation at NIF. To accurately reduce streak camera data a highly accurate temporal calibration is required. This article describes a technique for simultaneously generating a precise +/- 2 ps optical marker pulse (fiducial reference) and trains of precisely timed, short-duration optical pulses (so-called “comb” pulse trains) that are suitable for the timing calibrations. These optical pulse generators are used with the LLNL optical streak cameras. They are small, portable light sources that, in the comb mode, produce a series of temporally short, uniformly spaced optical pulses, using a laser diode source. Comb generators have been produced with pulse-train repetition rates up to 10 GHz at 780 nm, and somewhat lower frequencies at 664 nm. Individual pulses can be as short as 25-ps FWHM. Signal output is via a fiber-optic connector on the front panel of the generator box. The optical signal is transported from comb generator to streak camera through multi-mode, graded-index optical fiber

Infant mortality following male takeovers in wild geladas

Since Sugiyama's [1965] first observations of infanticide, empirical evidence from a multitude of primate species has supported the sexual selection hypothesis—the idea that males enhance their reproductive success by killing nonrelated, unweaned infants to hasten the mothers' return to fertility. Like other primates that live in social groups where paternity certainty is high, the social structure of geladas [ Theropithecus gelada ] suggests that infanticide by males could enhance their reproductive success. Nevertheless, empirical evidence for infanticide in this species is limited to anecdotal accounts. Using the timing of infant mortality and female reproductive and behavioral data collected across 26 months from a population of geladas living in the Simien Mountains National Park, Ethiopia, we test whether sexually selected infanticide occurs in this species. We also examine two additional hypotheses [noninfanticide hypothesis and generalized aggression hypothesis] for this population. Results suggest that sexually selected infanticide in geladas may, indeed, be a threat to females with dependent infants. First, male takeovers—the most likely time for infanticide—were associated with subsequently elevated rates of infant death [a 32-fold increase] comprising nearly 60% of all infant mortality. Second, females who lost infants during this period returned to fertility more quickly than if infants had lived [IBIs were 50% shorter], and third, all of these females were observed to mate with the new male. We found little to no support for other hypotheses. Finally, these results raise the possibility that anecdotal reports [from previous studies and this study] of pregnancy termination, accelerated weaning, and deceptive sexual swellings may represent female counterstrategies to male infanticide in geladas. Am. J. Primatol. 70:1152–1159, 2008. © 2008 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/61204/1/20614_ftp.pd

Very Low-Mass Stellar and Substellar Companions to Solar-Like Stars from MARVELS I: A Low Mass Ratio Stellar Companion to TYC 4110-01037-1 in a 79-day Orbit

TYC 4110-01037-1 has a low-mass stellar companion, whose small mass ratio and short orbital period are atypical amongst solar-like (Teff ~< 6000 K) binary systems. Our analysis of TYC 4110-01037-1 reveals it to be a moderately aged (~<5 Gyr) solar-like star having a mass of 1.07 +/- 0.08 MSun and radius of 0.99 +/- 0.18 RSun. We analyze 32 radial velocity measurements from the SDSS-III MARVELS survey as well as 6 supporting radial velocity measurements from the SARG spectrograph on the 3.6m TNG telescope obtained over a period of ~2 years. The best Keplerian orbital fit parameters were found to have a period of 78.994 +/- 0.012 days, an eccentricity of 0.1095 +/- 0.0023, and a semi-amplitude of 4199 +/- 11 m/s. We determine the minimum companion mass (if sin i = 1) to be 97.7 +/- 5.8 MJup. The system's companion to host star mass ratio, >0.087 +/- 0.003, places it at the lowest end of observed values for short period stellar companions to solar-like (Teff ~< 6000 K) stars. One possible way to create such a system would be if a triple-component stellar multiple broke up into a short period, low q binary during the cluster dispersal phase of its lifetime. A candidate tertiary body has been identified in the system via single-epoch, high contrast imagery. If this object is confirmed to be co-moving, we estimate it would be a dM4 star. We present these results in the context of our larger-scale effort to constrain the statistics of low mass stellar and brown dwarf companions to FGK-type stars via the MARVELS survey.Comment: 22 pages; accepted in A

Extent of exposure to environmental tobacco smoke (ETS) and its dose-response relation to respiratory health among adults

BACKGROUND: There is a dearth of standardized studies examining exposure to environmental tobacco smoke (ETS) and its relationship to respiratory health among adults in developing countries. METHODS: In 2004, the Syrian Center for Tobacco Studies (SCTS) conducted a population-based survey using stratified cluster sampling to look at issues related to environmental health of adults aged 18–65 years in Aleppo (2,500,000 inhabitants). Exposure to ETS was assessed from multiple self-reported indices combined into a composite score (maximum 22), while outcomes included both self-report (symptoms/diagnosis of asthma, bronchitis, and hay fever), and objective indices (spirometric assessment of FEV(1 )and FVC). Logistic and linear regression analyses were conducted to study the relation between ETS score and studied outcomes, whereby categorical (tertiles) and continuous scores were used respectively, to evaluate the association between ETS exposure and respiratory health, and explore the dose-response relationship of the association. RESULTS: Of 2038 participants, 1118 were current non-smokers with breath CO levels ≤ 10 ppm (27.1% men, mean age 34.7 years) and were included in the current analysis. The vast majority of study participants were exposed to ETS, whereby only 3.6% had ETS score levels ≤ 2. In general, there was a significant dose-response pattern in the relationship of ETS score with symptoms of asthma, hay fever, and bronchitis, but not with diagnoses of these outcomes. The magnitude of the effect was in the range of twofold increases in the frequency of symptoms reported in the high exposure group compared to the low exposure group. Severity of specific respiratory problems, as indicated by frequency of symptoms and health care utilization for respiratory problems, was not associated with ETS exposure. Exposure to ETS was associated with impaired lung function, indicative of airflow limitation, among women only. CONCLUSIONS: This study provides evidence for the alarming extent of exposure to ETS among adult non-smokers in Syria, and its dose-response relationship with respiratory symptoms of infectious and non-infectious nature. It calls for concerted efforts to increase awareness of this public health problem and to enforce regulations aimed at protecting non-smokers

Intersection between metabolic dysfunction, high fat diet consumption, and brain aging

Deleterious neurochemical, structural, and behavioral alterations are a seemingly unavoidable aspect of brain aging. However, the basis for these alterations, as well as the basis for the tremendous variability in regards to the degree to which these aspects are altered in aging individuals, remains to be elucidated. An increasing number of individuals regularly consume a diet high in fat, with high‐fat diet consumption known to be sufficient to promote metabolic dysfunction, although the links between high‐fat diet consumption and aging are only now beginning to be elucidated. In this review we discuss the potential role for age‐related metabolic disturbances serving as an important basis for deleterious perturbations in the aging brain. These data not only have important implications for understanding the basis of brain aging, but also may be important to the development of therapeutic interventions which promote successful brain aging.Fil: Uranga, Romina Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Bruce Keller, Annadora J.. State University of Louisiana; Estados UnidosFil: Morrison, Christopher D.. State University of Louisiana; Estados UnidosFil: Fernandez Kim, Sun Ok. State University of Louisiana; Estados UnidosFil: Ebenezer, Philip J.. State University of Louisiana; Estados UnidosFil: Zhang, Le. State University of Louisiana; Estados UnidosFil: Dasuri, Kalavathi. State University of Louisiana; Estados UnidosFil: Keller, Jeffrey N.. State University of Louisiana; Estados Unido

Mid- and Late-Life Diabetes in Relation to the Risk of Dementia: A Population-Based Twin Study

OBJECTIVE—We aimed to verify the association between diabetes and the risk of dementia, Alzheimer's disease, and vascular dementia in twins and to explore whether genetic and early-life environmental factors could contribute to this association

The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 Micron Spectrum of the Planetary-Mass Companion VHS 1256-1257 b

We present the highest fidelity spectrum to date of a planetary-mass object. VHS 1256 b is a $<$20 M$_\mathrm{Jup}$ widely separated ($\sim$8\arcsec, a = 150 au), young, planetary-mass companion that shares photometric colors and spectroscopic features with the directly imaged exoplanets HR 8799 c, d, and e. As an L-to-T transition object, VHS 1256 b exists along the region of the color-magnitude diagram where substellar atmospheres transition from cloudy to clear. We observed VHS 1256~b with \textit{JWST}'s NIRSpec IFU and MIRI MRS modes for coverage from 1 $\mu$m to 20 $\mu$m at resolutions of $\sim$1,000 - 3,700. Water, methane, carbon monoxide, carbon dioxide, sodium, and potassium are observed in several portions of the \textit{JWST} spectrum based on comparisons from template brown dwarf spectra, molecular opacities, and atmospheric models. The spectral shape of VHS 1256 b is influenced by disequilibrium chemistry and clouds. We directly detect silicate clouds, the first such detection reported for a planetary-mass companion.Comment: Accepted ApJL Iterations of spectra reduced by the ERS team are hosted at this link: https://github.com/bemiles/JWST_VHS1256b_Reduction/tree/main/reduced_spectr

The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems IV: NIRISS Aperture Masking Interferometry Performance and Lessons Learned

We present a performance analysis for the aperture masking interferometry (AMI) mode on board the James Webb Space Telescope Near Infrared Imager and Slitless Spectrograph (JWST/NIRISS). Thanks to self-calibrating observables, AMI accesses inner working angles down to and even within the classical diffraction limit. The scientific potential of this mode has recently been demonstrated by the Early Release Science (ERS) 1386 program with a deep search for close-in companions in the HIP 65426 exoplanetary system. As part of ERS 1386, we use the same dataset to explore the random, static, and calibration errors of NIRISS AMI observables. We compare the observed noise properties and achievable contrast to theoretical predictions. We explore possible sources of calibration errors, and show that differences in charge migration between the observations of HIP 65426 and point-spread function calibration stars can account for the achieved contrast curves. Lastly, we use self-calibration tests to demonstrate that with adequate calibration, NIRISS AMI can reach contrast levels of $\sim9-10$ mag. These tests lead us to observation planning recommendations and strongly motivate future studies aimed at producing sophisticated calibration strategies taking these systematic effects into account. This will unlock the unprecedented capabilities of JWST/NIRISS AMI, with sensitivity to significantly colder, lower mass exoplanets than ground-based setups at orbital separations inaccessible to JWST coronagraphy.Comment: 20 pages, 12 figures, submitted to AAS Journal

The \textit{JWST} Early Release Science Program for Direct Observations of Exoplanetary Systems III: Aperture Masking Interferometric Observations of the star HIP\,65426 at 3.8 μm\boldsymbol{3.8\,\rm{\mu m}}

We present aperture masking interferometry (AMI) observations of the star HIP 65426 at $3.8\,\rm{\mu m}$ as a part of the \textit{JWST} Direct Imaging Early Release Science (ERS) program obtained using the Near Infrared Imager and Slitless Spectrograph (NIRISS) instrument. This mode provides access to very small inner working angles (even separations slightly below the Michelson limit of ${}0.5\lambda/D$ for an interferometer), which are inaccessible with the classical inner working angles of the \textit{JWST} coronagraphs. When combined with \textit{JWST}'s unprecedented infrared sensitivity, this mode has the potential to probe a new portion of parameter space across a wide array of astronomical observations. Using this mode, we are able to achieve a contrast of $\Delta m_{F380M}{\sim }7.8$\,mag relative to the host star at a separation of {\sim}0.07\arcsec but detect no additional companions interior to the known companion HIP\,65426\,b. Our observations thus rule out companions more massive than 10{-}12\,\rm{M\textsubscript{Jup}} at separations ${\sim}10{-}20\,\rm{au}$ from HIP\,65426, a region out of reach of ground or space-based coronagraphic imaging. These observations confirm that the AMI mode on \textit{JWST} is sensitive to planetary mass companions orbiting at the water frost line, even for more distant stars at $\sim$100\,pc. This result will allow the planning and successful execution of future observations to probe the inner regions of nearby stellar systems, opening essentially unexplored parameter space.Comment: 15 pages, 9 figures, submitted to ApJ Letter