The federally threatened California red-legged frog
Rana aurora draytonii occupies both aquatic and terrestrial habitats in its adult life stage. The terrestrial activities of this species are not ...well known and require documentation to assist in the development of appropriate levels of protection under the US Endangered Species Act. We studied the terrestrial activities of radio-tagged red-legged frogs (
n=8–26) inhabiting a coastal watershed in Santa Cruz County, California, during 1997–1998. In particular, we investigated (1) the use of terrestrial habitats by non-migrating adults in relation to season, breeding chronology, and precipitation, and (2) adult migration behavior, including seasonal timing, duration, distances traveled, and the use of corridors. Non-migrating red-legged frogs occupied terrestrial habitats briefly (median=4–6 days) following infrequent summer rains, but resided nearly continuously on land (median=20–30 days) from the onset of the winter wet-season until breeding activities commenced 1–2 months later. All of the non-migrating frogs remained within 130 m of their aquatic site of residence (median <25 m). Intervals spent on land were again brief during mid/late winter (median=1–4 days), despite frequent and copious rainfall. Adult migration to and from breeding sites occurred from late October through mid-May (wet season). We monitored 25 migration events between aquatic sites that were 200–2800 m apart. Short distance movements (<300 m) were completed in 1–3 days, longer movements required up to 2 months. Most migrating frogs moved overland in approximately straight lines to target sites without apparent regard to vegetation type or topography. Riparian corridors were neither essential nor preferred as migration routes. Frogs traveling overland occurred in upland habitats as far as 500 m from water. Approximately 11–22% of the adult population was estimated to migrate to and from breeding sites annually, whereas the bulk of the adult population was resident at these sites. Adequate protection of red-legged frog populations inhabiting relatively undeveloped landscapes is liable to be achieved by retaining an array of suitable habitat elements within at least 100 m of occupied aquatic sites, and by imposing seasonal limitations on detrimental human activities occurring within this zone. Specific protections for migrating frogs are probably unwarranted in forest and rangeland environments because dispersal habitat is ubiquitous and migrating frogs are widely distributed across the landscape in space and time.
Data on sexual consortships in a troop of chacma baboons are analyzed in relation to a priority-of-access model and to critical demographic and social variables. The data show a robust association ...between adult male rank and mating success, and a close approximation to priority-of-access type mating. Principal findings were: (1) Mating activity peaked during the four most likely days of ovulation, and was greater on conceptive than on nonconceptive cycles. (2) On each day of estrus, males of the alpha rank consorted more frequently than did males of other ranks for both classes of cycles. (3) Moreover, on each day of estrus, alpha males consorted at higher rates on conceptive cycles than they did on nonconceptive cycles. (4) Male dominance rank and consorting success were positively correlated, including a perfect rank correlation on conceptive cycles. (5) Mean consort duration was also positively correlated with male dominance rank. (6) The most striking aspect of male mating patterns was the predominance of alpha males. Male dominance rank and consort success were in qualitative but not perfect quantitative agreement with predictions of a priority-of-access model. Alpha males consorted on 86% of the days and 94% of the conceptive cycles they were expected to, and were selective of conceptive over nonconceptive cycles. (7) The size of the adult male cohort had no effect on the consort success of alpha males. (8) Alpha male consort success was reduced during intervals when two or more females were synchronously in estrus. Inconsistent results from other savanna baboon field studies have often led to the conclusion that dominance rank is not important as a determinant of male mating success. Analysis of the literature indicates that some of the reported variability among studies is explained by factors that are associated with differences in group demography. In addition, the importance of male dominance rank has often been treated superficially in discussions emphasizing alternative mating tactics, due in part to the uneven representation of published accounts emerging from individual study sites. I conclude that there is a general, underlying relationship between male dominance rank and access to mates in savanna baboons. Dominance rank is inarguably the primary determinant of mating success among high-ranking males, while the mating success of subordinate males is determined both by rank and the extent to which coalitions are expressed in the group. Rank/mating measures tend to be strongest in the chacma subspecies, among which male-male coalitions over mates are unknown. Male-male competition based in both solo and coalitional tactics appears to dominate the expression of individual partner preferences.
Academic medical centers should try to become therapeutic organizations. Academic medical centers are clinics and hospitals that are affiliated with a medical school. A therapeutic organization is ...one that adopts many of the characteristics of an individual doctor. These include scientific and technical competence, an understanding of suffering, death and dying, knowledge of the placebo effect and its role in scientific health care practice, and an ability to communicate and especially to listen. Academic medical centers that adopt this model will combine humanism with scientific and technical excellence.
Principal Component Analysis (PCA) was used to derive estuarine salinity zones based on field data on the salinity ranges of 316 species/life stages in the mid-Atlantic region (chiefly Chesapeake Bay ...and Delaware Bay species). Application of PCA to the data matrix showed that the structure underlying a diversity of salinity distributions could be represented by only five Principal Components corresponding to five overlapping salinity zones: freshwater to 4‰, 2-14‰, 11-18‰, 16-27‰, and 24‰ to marine. The derived salinity zonation showed both differences and similarities to the Venice System of estuarine zonation. However, unlike the static and essentially descriptive Venice System, the new method will allow researchers to establish biologically-relevant local salinity zones, and then develop hypotheses about the processes that give rise to the resulting patterns. Examples of this procedure are given for the mid-Atlantic region. The method used here may also be useful for studying distributions across other environmental gradients, such as temperature, pH, substrate, turbidity, vegetation, or latitude.
Abstract
We present new near-infrared Gemini Planet Imager (GPI) spectroscopy of HD 206893 B, a substellar companion orbiting within the debris disk of its F5V star. The
J
,
H
,
K1
, and
K2
spectra ...from GPI demonstrate the extraordinarily red colors of the object, confirming it as the reddest substellar object observed to date. The significant flux increase throughout the infrared presents a challenging atmosphere to model with existing grids. Best-fit values vary from 1200 to 1800 K for effective temperature and from 3.0 to 5.0 for log(
g
), depending on which individual wavelength band is fit and which model suite is applied. The extreme redness of the companion can be partially reconciled by invoking a high-altitude layer of submicron dust particles, similar to dereddening approaches applied to the peculiar red field L dwarf population. However, reconciling the HD 206893 B spectra with even those of the reddest low-gravity L dwarf spectra still requires the contribution of additional atmospheric dust, potentially due to the debris disk environment in which the companion resides. Orbit fitting from 4 yr of astrometric monitoring is consistent with a ∼30 yr period, an orbital inclination of 147°, and a semimajor axis of 10 au, well within the estimated disk inner radius of ∼50 au. As one of a very few substellar companions imaged interior to a circumstellar disk, the properties of this system offer important dynamical constraints on companion–disk interaction and provide a benchmark for substellar and planetary atmospheric study.
ABSTRACT
SN 2017jgh is a type IIb supernova discovered by Pan-STARRS during the C16/C17 campaigns of the Kepler/K2 mission. Here, we present the Kepler/K2 and ground based observations of SN 2017jgh, ...which captured the shock cooling of the progenitor shock breakout with an unprecedented cadence. This event presents a unique opportunity to investigate the progenitors of stripped envelope supernovae. By fitting analytical models to the SN 2017jgh light curve, we find that the progenitor of SN 2017jgh was likely a yellow supergiant with an envelope radius of $\sim 50{\!-\!}290\, {\rm R}_{\odot }$, and an envelope mass of $\sim 0{\!-\!}1.7\, {\rm M}_{\odot }$. SN 2017jgh likely had a shock velocity of ∼7500−10 300 km s−1. Additionally, we use the light curve of SN 2017jgh to investigate how early observations of the rise contribute to constraints on progenitor models. Fitting just the ground based observations, we find an envelope radius of $\sim 50{\!-\!}330\, {\rm R}_{\odot }$, an envelope mass of $\sim 0.3{\!-\!}1.7\, {\rm M}_{\odot }$ and a shock velocity of ∼9000−15 000 km s−1. Without the rise, the explosion time cannot be well constrained that leads to a systematic offset in the velocity parameter and larger uncertainties in the mass and radius. Therefore, it is likely that progenitor property estimates through these models may have larger systematic uncertainties than previously calculated.
With the PACS instrument on Herschel, 134 low mass members of the Taurus star-forming region spanning the M4-L0 spectral type range and covering the transition from low mass stars to brown dwarfs ...were observed. Combining the new Herschel results with other Herschel programs, a total of 150 of the 154 M4-L0 Taurus members have observations, and we have added an additional 3 targets from Spitzer to form the 153-object TBOSS (Taurus Boundary of Stellar/Substellar) sample, a 99% complete study. Among the 150 targets, 70 μm flux densities were measured for 7 of the 7 Class I objects, 48 of the 67 Class II objects, and 3 of the 76 Class III objects. For the detected Class II objects, the median 70 μm flux density level declines with spectral type; however, the distribution of excess relative to central object flux density does not change across the stellar/substellar boundary in the M4-L0 range. Connecting the 70 μm TBOSS values with the results from K0-M3 Class II members results in the first comprehensive census of far-IR emission across the full mass spectrum of the stellar and substellar population of a star-forming region, and the median flux density declines with spectral type in a trend analogous to the flux density decline expected for the central objects. Spectral energy distributions (SEDs) were constructed for all TBOSS targets covering the optical to far-IR range and extending to the submm/mm for a subset of sources with longer wavelength data. Based on an initial exploration of the impact of different physical parameters on the Herschel flux densities, geometrical factors such as inclination and structural parameters such as scale height and flaring have the largest influence on the flux densities in the PACS bands. From the 24 μm to 70 μm spectral index of the SEDs, 5 new candidate transition disks were identified. Considering the previously known and new candidate transition disks, the spectral indices over longer wavelengths (≥70 μm) are not distinct from those of the full Class II population, suggesting that the outer regions of the transition disks are similar to Class II disks. The steep 24 μm to 70 μm slope for a subset of 8 TBOSS targets may be an indication of truncated disks in these systems, however additional measurements are required to establish the outer radii of these disks conclusively. From existing high angular resolution companion search observations, two examples of mixed pair systems that include secondaries with disks were measured in the Herschel data. Finally, comparing the TBOSS results with a Herschel study of Ophiuchus brown dwarfs reveals a lower fraction of disks around the Taurus substellar population with flux densities comparable to the Ophiuchus disks. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia, and with important participation from NASA.Appendices are available in electronic form at www.aanda.org Tables 1, 2, 4, 5, and A.1-A.4 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/570/A29
We present the preliminary findings of an investigation of the multiplicity of debris disk stars identified within our Volume-limited A-star (VAST) multiplicity survey. Previous studies have produced ...conflicting results regarding the multiplicity fraction of debris disk-hosting stars compared with non-excess stars. By combining our large-scale volume-limited AO survey of A-type stars with the all-sky WISE catalogue, we have investigated the frequency of binary companions to a large sample of A-type stars with and without measured 22μm excess. The results of this study will allow for a greater understanding of the interaction between a companion star and a circumstellar debris disk, informing future study into the formation and stability of planetary-mass companions within binary systems.
With the combination of Herschel PACS (far-IR), submillimeter (submm) and millimeter (mm) ground-based observations, we are leading an investigation of all members with spectral types M4 and onwards ...in the Taurus star-forming region. This complete census spans the stellar to substellar boundary (M6.25), and the wavelength range covers the transition from optically thick to optically thin emission. From our Hershel PACS observations of ~135 sources, we obtain a detection rate of ~40% at 70 μm and a detection rate of ~20% at 160 μm, and provide the first far-IR measurements for the majority of these members. With our complementary submm and mm observations, best fit SED models from the radiative transfer code MCFOST will be used to infer disk properties such as scale height, mass, outer radius and maximum dust grain size. These comprehensive population statistics of disks are critical for testing star/brown dwarf and planet formation models around these later type members of Taurus.
We present new near-infrared Gemini Planet Imager (GPI) spectroscopy of HD 206893 B, a substellar companion orbiting within the debris disk of its F5V star. The J, H, K1, and K2 spectra from GPI ...demonstrate the extraordinarily red colors of the object, confirming it as the reddest substellar object observed to date. The significant flux increase throughout the infrared presents a challenging atmosphere to model with existing grids. Best-fit values vary from 1200 to 1800 K for effective temperature and from 3.0 to 5.0 for log(g), depending on which individual wavelength band is fit and which model suite is applied. The extreme redness of the companion can be partially reconciled by invoking a high-altitude layer of submicron dust particles, similar to dereddening approaches applied to the peculiar red field L dwarf population. However, reconciling the HD 206893 B spectra with even those of the reddest low-gravity L dwarf spectra still requires the contribution of additional atmospheric dust, potentially due to the debris disk environment in which the companion resides. Orbit fitting from 4 yr of astrometric monitoring is consistent with a ∼30 yr period, an orbital inclination of 147°, and a semimajor axis of 10 au, well within the estimated disk inner radius of ∼50 au. As one of a very few substellar companions imaged interior to a circumstellar disk, the properties of this system offer important dynamical constraints on companion–disk interaction and provide a benchmark for substellar and planetary atmospheric study.
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