Understanding and Finding Solutions to the Problem of Sedimentation in the National Wildlife Refuge System

The National Wildlife Refuge System (Refuge System) is a collection of public lands maintained by the U.S. Fish and Wildlife Service for migratory birds and other wildlife. Wetlands on individual National Wildlife Refuges (Refuges) may be at risk of increased sedimentation because of land use and water management practices. Increased sedimentation can reduce wetland habitat quality by altering hydrologic function, degrading water quality, and inhibiting growth of vegetation and invertebrates. On Refuges negatively affected by increased sedimentation, managers have to address complex questions about how to best remediate and mitigate the negative effects. The best way to account for these complexities is often not clear. On other Refuges, managers may not know whether sedimentation is a problem. Decision makers in the Refuge System may need to allocate resources to studying which Refuges could be at risk. Such analyses would help them understand where to direct support for managing increased sedimentation. In this paper, we summarize a case study demonstrating the use of decision-analytic tools in the development of a sedimentation management plan for Agassiz National Wildlife Refuge, Minnesota. Using what we learned from that process, we surveyed other Refuges in U.S. Fish and Wildlife Service Region 3 (an area encompassing the states of Illinois, Indiana, Iowa, Ohio, Michigan, Minnesota, Missouri, and Wisconsin) and Region 6 (an area encompassing the states of Colorado, Kansas, Montana, Nebraska, North Dakota, South Dakota, Utah, and Wyoming) about whether they experience sediment-related impacts to management. Our results show that cases of management being negatively affected by increased sedimentation are not isolated. We suggest that the Refuge System conduct a comprehensive and systematic assessment of increased sedimentation among Refuges to understand the importance of sedimentation in context with other management problems that Refuges face. The results of such an assessment could guide how the Refuge System allocates resources to studying and managing widespread stressors

The Chandra Deep Field North Survey. IX. Extended X-ray Sources

The ~1 Ms Chandra Deep Field North observation is used to study the extended X-ray sources in the region surrounding the Hubble Deep Field North (HDF-N), yielding the most sensitive probe of extended X-ray emission at cosmological distances to date. A total of six such sources are detected, the majority of which align with small numbers of optically bright galaxies. Their angular sizes, band ratios, and X-ray luminosities -- assuming they lie at the same distances as the galaxies coincident with the X-ray emission -- are generally consistent with the properties found for nearby groups of galaxies. One source is notably different and is likely to be a poor-to-moderate X-ray cluster at high redshift (i.e., z > 0.7). We are also able to place strong constraints on the optically detected cluster of galaxies ClG 1236+6215 at z=0.85 and the wide-angle-tail radio galaxy VLA J123725.7+621128 at z~1-2. With rest-frame 0.5--2.0 keV X-ray luminosities of <(3-15)e42 ergs s^{-1}, the environments of both sources are either likely to have a significant deficit of hot intra-cluster gas compared to local clusters of galaxies, or they are X-ray groups. We find the surface density of extended X-ray sources in this observation to be 167 (+97,-67) deg^{-2} at a limiting soft-band flux of approximately 3e-16 ergs s^{-1} cm^{-2}. No evolution in the X-ray luminosity function of clusters is needed to explain this value. (Abridged)Comment: 16 pages, 14 figures (8 color), LaTeX emulateapj5.sty, accepted for publication by the Astronomical Journal. Manuscript with full resolution embedded images available at http://www.astro.psu.edu/users/niel/hdf/hdf-chandra.htm

Constraining q_0 with Cluster Gas Mass Fractions: A Feasibility Study

As the largest gravitationally bound objects in the universe, clusters of galaxies may contain a fair sample of the baryonic mass fraction of the universe. Since the gas mass fraction from the hot ICM is believed to be constant in time, the value of the cosmological deceleration parameter $q_0$ can be determined by comparing the calculated gas mass fraction in nearby and distant clusters (Pen 1997). To test the potential of this method, we compare the gas fractions derived for a sample of luminous ($L_X > 10^{45}$erg s$^{-1}$), nearby clusters with those calculated for eight luminous, distant ($0.3 < z < 0.6$) clusters using ASCA and ROSAT observations. For consistency, we evaluate the gas mass fraction at a fixed physical radius of 1 $h_{50}^{-1}$ Mpc (assuming $q_0=0.0$). We find a best fit value of $q_0 = 0.07$ with -0.47 < q_0 < 0.67 at 95% confidence. We also determine the gas fraction using the method of Evrard, Metzler, & Navarro (1997) to find the total mass within $r_{500}$, the radius where the mean overdensity of matter is 500 times the critical density. In simulations, this method reduces the scatter in the determination of gravitational mass without biasing the mean. We find that it also reduces the scatter in actual observations for nearby clusters, but not as much as simulations suggest. Using this method, the best fit value is $q_0 = 0.04$ with -0.50 < q_0 < 0.64. The excellent agreement between these two methods suggests that this may be a useful technique for determining $q_0$. The constraints on $q_0$ should improve as more distant clusters are studied and precise temperature profiles are measured to large radii.Comment: 8 pages, 4 figures, uses emulateapj.sty, onecolfloat.st

Linking Categorical and Dimensional Approaches to Assess Food-Related Emotions

Reflecting the two main prevailing and opposing views on the nature of emotions, emotional responses to food and beverages are typically measured using either (a) a categorical (lexicon-based) approach where users select or rate the terms that best express their food-related feelings or (b) a dimensional approach where they rate perceived food items along the dimensions of valence and arousal. Relating these two approaches is problematic since a response in terms of valence and arousal is not easily expressed in terms of emotions (like happy or disgusted). In this study, we linked the dimensional approach to a categorical approach by establishing mapping between a set of 25 emotion terms (EsSense25) and the valence&ndash;arousal space (via the EmojiGrid graphical response tool), using a set of 20 food images. In two &lsquo;matching&rsquo; tasks, the participants first imagined how the food shown in a given image would make them feel and then reported either the emotional terms or the combination of valence and arousal that best described their feelings. In two labeling tasks, the participants first imagined experiencing a given emotion term and then they selected either the foods (images) that appeared capable to elicit that feeling or reported the combination of valence and arousal that best reflected that feeling. By combining (1) the mapping between the emotion terms and the food images with (2) the mapping of the food images to the valence&ndash;arousal space, we established (3) an indirect (via the images) mapping of the emotion terms to the valence&ndash;arousal space. The results show that the mapping between terms and images was reliable and that the linkages have straightforward and meaningful interpretations. The valence and arousal values that were assigned to the emotion terms through indirect mapping to the valence&ndash;arousal space were typically less extreme than those that were assigned through direct mapping

The interactive effect of change in perceived stress and trait anxiety on vagal recovery from cognitive challenge

The present study tested the hypothesis that the change in state negative affect (measured as perceived stress) after cognitive challenge moderates the relationship of trait anxiety and anger to vagal recovery from that challenge. Cardiac vagal control (assessed using heart rate variability) and respiratory rate were measured in a sample of 905 participants from the Midlife in the United States Study. Cognitive challenges consisted of computerized mental arithmetic and Stroop color–word matching tasks. Multiple regression analyses controlling for the effects of the demographic, lifestyle, and medical factors influencing cardiac vagal control showed a significant moderating effect of change in perceived stress on the relationship of trait anxiety to vagal recovery from cognitive challenges (Beta = .253, p = .013). After adjustment for respiratory rate, this effect became marginally significant (Beta = .177, p = .037). In contrast, for the relationship of trait anger to vagal recovery, this effect was not significant either before (Beta = .141, p = .257) or after (Beta = .186, p = .072) adjusting for respiratory rate. Secondary analyses revealed that among the individuals with higher levels of trait anxiety, greater reductions in perceived stress were associated with greater increases in cardiac vagal control after the challenge. In contrast, among the individuals with lower levels of trait anxiety, changes in perceived stress had no impact on vagal recovery. Therefore, change in perceived stress moderates the relationship of trait anxiety, but not trait anger, to vagal recovery from cognitive challenge

Synchronized Audio-Visual Transients Drive Efficient Visual Search for Motion-in-Depth

In natural audio-visual environments, a change in depth is usually correlated with a change in loudness. In the present study, we investigated whether correlating changes in disparity and loudness would provide a functional advantage in binding disparity and sound amplitude in a visual search paradigm. To test this hypothesis, we used a method similar to that used by van der Burg et al. to show that non-spatial transient (square-wave) modulations of loudness can drastically improve spatial visual search for a correlated luminance modulation. We used dynamic random-dot stereogram displays to produce pure disparity modulations. Target and distractors were small disparity-defined squares (either 6 or 10 in total). Each square moved back and forth in depth in front of the background plane at different phases. The target’s depth modulation was synchronized with an amplitude-modulated auditory tone. Visual and auditory modulations were always congruent (both sine-wave or square-wave). In a speeded search task, five observers were asked to identify the target as quickly as possible. Results show a significant improvement in visual search times in the square-wave condition compared to the sine condition, suggesting that transient auditory information can efficiently drive visual search in the disparity domain. In a second experiment, participants performed the same task in the absence of sound and showed a clear set-size effect in both modulation conditions. In a third experiment, we correlated the sound with a distractor instead of the target. This produced longer search times, indicating that the correlation is not easily ignored

Heart Rate Recovery After Cognitive Challenge Is Preserved With Age

Objective: To investigate the effect of age on heart rate recovery (HRR) from cognitive challenge. Background: Aging is an independent risk factor for the development of cardiovascular disease. HRR from exercise is an established predictor of cardiac morbidity and mortality, and evidence suggests that HRR from cognitive challenge is predictive of cardiac morbidity as well. Aging is associated with delayed HRR from exercise stress, but little is known about the effect of aging on HRR from psychological stress. We tested the hypothesis that age would be related to delayed HRR from psychological stress. Methods: HRR post exposure to cognitive challenge (mental arithmetic and Stroop) was investigated in a sample of 436 participants aged 35 to 84 years in MIDUS II, a national study of health and well-being. HRR was measured as 1) the amount of change from the stress level; 2) time to recover; and 3) the area under the curve. The analyses were controlled for medical comorbidities and medications that influence HR, such as body mass index, smoking, sex, menopausal status, and amount of physical activity/exercise. Results: There was no effect for age on HRR as evaluated by all three recovery assessment methods. Conclusions: Contrary to expectation and in contrast to findings concerning HRR from exercise, HRR from cognitive challenge was preserved with age. These findings require further inquiry into differential mechanism(s) underlying HRR from psychological versus exercise stress, including any role for improved emotion regulation with greater age

ESA Voyage 2050 white paper: Unveiling the faint ultraviolet Universe

New and unique science opportunities in several different fields of astrophysics are offered by conducting spectroscopic studies of the Universe in the ultraviolet (UV), a wavelength regime that is not accessible from the ground. We present some of the scientific challenges that can be addressed with a space-based mission in 2035 - 2050. (1) By detecting the intergalactic medium in emission it will be possible to unveil the cosmic web, whose existence is predicted by current theories of structure formation, but it has not been probed yet. (2) Observations of the neutral gas distribution (by mapping the Lyman-alpha emission) in low-redshift galaxy cluster members will clarify the efficiency with which ram-pressure stripping removes the gas from galaxies and the role of the environment in quenching star formation. (3) By observing statistical samples of supernovae in the UV it will be possible to characterize the progenitor population of core-collapse supernovae, providing the initial conditions for any forward-modeling simulation and allowing the community to progress in the understanding of the explosion mechanism of stars and the final stages of stellar evolution. (4) Targeting populations of accreting white dwarfs in globular clusters it will be possible to constrain the evolution and fate of these stars and investigate the properties of the most compact systems with the shortest orbital periods which are expected to be the brightest low frequency gravitational wave sources. A UV-optimized telescope (wavelength range ~ 90 - 350 nm), equipped with a panoramic integral field spectrograph with a large field of view (FoV ~ 1 x 1 arcmin^2), with medium spectral (R = 4000) and spatial (~ 1" - 3") resolution will allow the community to simultaneously obtain spectral and photometric information of the targets, and tackle the science questions presented in this paper

Vagal Recovery From Cognitive Challenge Moderates Age-Related Deficits in Executive Functioning

Decline in executive functioning (EF) is a hallmark of cognitive aging. We have previously reported that faster vagal recovery from cognitive challenge is associated with better EF. This study examined the association between vagal recovery from cognitive challenge and age-related differences in EF among 817 participants in the Midlife in the U.S. study (aged 35–86). Cardiac vagal control was measured as high-frequency heart rate variability. Vagal recovery moderated the association between age and EF (β = .811, p = .004). Secondary analyses revealed that older participants (aged 65–86) with faster vagal recovery had superior EF compared to their peers who had slower vagal recovery. In contrast, among younger (aged 35–54) and middle-aged (aged 55–64) participants, vagal recovery was not associated with EF. We conclude that faster vagal recovery from cognitive challenge is associated with reduced deficits in EF among older, but not younger individuals

"Peeling property" for linearized gravity in null coordinates

A complete description of the linearized gravitational field on a flat background is given in terms of gauge-independent quasilocal quantities. This is an extension of the results from gr-qc/9801068. Asymptotic spherical quasilocal parameterization of the Weyl field and its relation with Einstein equations is presented. The field equations are equivalent to the wave equation. A generalization for Schwarzschild background is developed and the axial part of gravitational field is fully analyzed. In the case of axial degree of freedom for linearized gravitational field the corresponding generalization of the d'Alembert operator is a Regge-Wheeler equation. Finally, the asymptotics at null infinity is investigated and strong peeling property for axial waves is proved.Comment: 27 page