Juvenile salamander dispersal and use of terrestrial microhabitat cues

Abstract only availableThe effects of deforestation are profound on amphibian populations. In order to balance land use practices with amphibian conservation, biologists and land managers must understand the habitat requirements of amphibians at all life stages. Ambystomatid salamanders have an aquatic larval stage followed by metamorphosis and dispersal into terrestrial habitats. In our study, we were interested in understanding the olfactory cues juvenile salamanders perceive from the microhabitat surrounding their natal pond that can lead them to a moist, cool environment. In particular, we wanted to know if forest-associated salamanders receive an olfactory cue from forest leaf litter that they do not receive from grassland litter. Further, if they are getting the cue from leaf litter, is it present in both decomposing and freshly fallen leaves? We hypothesized that forest-associated salamanders would respond positively to cues in forest leaf litter, and that because decomposing leaf litter contains fungi and other decomposing organisms, it would provide a better cue than fresh leaves. To test our hypothesis, we conducted experimental choice tests with two salamander species (n=72). Each salamander was presented with two substrate options. First we tested grassland versus forest litter, followed by decomposing versus freshly fallen leaves. An individual's substrate location ,recorded at 3- minute intervals for 60 minutes determined preference. Ambystoma maculatum, a forest dependent species, showed a preference for forest leaf litter, suggesting they use an olfactory cue found in forest litter to select favorable microhabitats. The second experiment demonstrated a preference for decomposing rather than fresh leaves by both species, suggesting the cue is from forest-associated fungi and decomposers. Immediately fallowing timber harvesting, there is likely a lag period in which the substrate retains the forest olfactory cues. The result is an ecological trap for dispersing juvenile salamanders, which may select clearcuts while the litter maintains the favorable cue.NSF grant to R. Semlitsc

The effect of host structure on the selectivity and mechanism of supramolecular catalysis of Prins cyclizations.

The effect of host structure on the selectivity and mechanism of intramolecular Prins reactions is evaluated using K12Ga4L6 tetrahedral catalysts. The host structure was varied by modifying the structure of the chelating moieties and the size of the aromatic spacers. While variation in chelator substituents was generally observed to affect changes in rate but not selectivity, changing the host spacer afforded differences in efficiency and product diastereoselectivity. An extremely high number of turnovers (up to 840) was observed. Maximum rate accelerations were measured to be on the order of 105, which numbers among the largest magnitudes of transition state stabilization measured with a synthetic host-catalyst. Host/guest size effects were observed to play an important role in host-mediated enantioselectivity

Long period planets from dynamical relaxation

Recent imaging campaigns indicate the likely existence of massive planets (~ 1-10 MJ) on ~1000 year orbits about a few percent of stars. Such objects are not easily explained in most current planet formation models. In this Letter we use ensembles of 100 N-body simulations to evaluate the potential for planet scattering during relaxation of dynamically active systems to explain the population of giant planets with projected separations up to a few 100 AU. We find that such a mechanism could indeed be at play, and that statistical samples of long period planets could place interesting constraints on early stage planet formation scenarios. Results from direct imaging and microlensing surveys are complementary probes of this dynamical relaxation process.Comment: Accepted for publication in ApJ Letters, this is final versio

U.S. Department of Energy Competition: Solar District Cup

The Solar District Cup is a two-semester design competition sponsored by the U.S. Dept. of Energy. For this competition, teams from across the nation are tasked with designing the most efficient and cost-effective solar plus storage system for a unique district case. The Embry Riddle team was tasked with designing such a system for New Mexico State University (NMSU) in Las Cruses, NM. During the first semester, the team\u27s primary focus was on selecting the photovoltaic panels and equipment used, placing/wiring that equipment across the campus, and developing a plan that would finish construction of the system within 6-months. For this second semester our focus has been on how to incorporate an energy storage system that will allow NMSU to lower their daily peak demand charges without affecting the 6-month construction period, and, per the competition requirements, ensure that the entire project will be fully paid back within 25 years. Our results showcase our proposed design, with a focus on the benefits associated with installing such a system

Habitable Climates: The Influence of Eccentricity

In the outer regions of the habitable zone, the risk of transitioning into a globally frozen "snowball" state poses a threat to the habitability of planets with the capacity to host water-based life. We use a one-dimensional energy balance climate model (EBM) to examine how obliquity, spin rate, orbital eccentricity, and ocean coverage might influence the onset of such a snowball state. For an exoplanet, these parameters may be strikingly different from the values observed for Earth. Since, for constant semimajor axis, the annual mean stellar irradiation scales with (1-e^2)^(-1/2), one might expect the greatest habitable semimajor axis (for fixed atmospheric composition) to scale as (1-e^2)^(-1/4). We find that this standard ansatz provides a reasonable lower bound on the outer boundary of the habitable zone, but the influence of obliquity and ocean fraction can be profound in the context of planets on eccentric orbits. For planets with eccentricity 0.5, our EBM suggests that the greatest habitable semimajor axis can vary by more than 0.8 AU (78%!) depending on obliquity, with higher obliquity worlds generally more stable against snowball transitions. One might also expect that the long winter at an eccentric planet's apoastron would render it more susceptible to global freezing. Our models suggest that this is not a significant risk for Earth-like planets around Sun-like stars since such planets are buffered by the thermal inertia provided by oceans covering at least 10% of their surface. Since planets on eccentric orbits spend much of their year particularly far from the star, such worlds might turn out to be especially good targets for direct observations with missions such as TPF-Darwin. Nevertheless, the extreme temperature variations achieved on highly eccentric exo-Earths raise questions about the adaptability of life to marginally or transiently habitable conditions.Comment: References added, text and figures updated, accepted by Ap

Biological, Social, and Urban Design Factors Affecting Young Street Tree Mortality in New York City

In dense metropolitan areas, there are many factors including traffic congestion, building development and social organizations that may impact the health of street trees. The focus of this study is to better understand how social, biological and urban design factors affect the mortality rates of newly planted street trees. Prior analyses of street trees planted by the New York City Department of Parks & Recreation between 1999 and 2003 (n=45,094) found 91.3% of those trees were alive after two years and 8.7% were either standing dead or missing completely. Using a site assessment tool, a randomly selected sample of 13,405 of these trees was surveyed throughout the City of New York during the summers of 2006 and 2007. Overall, 74.3% of the sample trees were alive when surveyed and the remainder were either standing dead or missing. Results of our initial analyses reveal that highest mortality rates occur within the first few years after planting, and that land use has a significant effect on street tree mortality. Trees planted in one- and two-family residential areas had the highest survival rates (82.7%), while young street trees planted in industrial areas, open space and vacant land had the lowest rates of street tree survival (60.3% -62.9%). Also significant in predicting street tree success and failure are species type, tree pit enhancements, direct tree care/stewardship, and local traffic conditions. These results are intended to inform urban forest managers in making decisions about the best conditions for planting new street trees

The effect of iliac crest autograft on the outcome of fusion in the setting of degenerative spondylolisthesis: a subgroup analysis of the Spine Patient Outcomes Research Trial (SPORT).

BACKGROUND: There is considerable controversy about the long-term morbidity associated with the use of posterior autologous iliac crest bone graft for lumbar spine fusion procedures compared with the use of bone-graft substitutes. The hypothesis of this study was that there is no long-term difference in outcome for patients who had posterior lumbar fusion with or without iliac crest autograft. METHODS: The study population includes patients enrolled in the degenerative spondylolisthesis cohort of the Spine Patient Outcomes Research Trial who underwent lumbar spinal fusion. Patients were divided according to whether they had or had not received posterior autologous iliac crest bone graft. RESULTS: There were 108 patients who had fusion with iliac crest autograft and 246 who had fusion without iliac crest autograft. There were no baseline differences between groups in demographic characteristics, comorbidities, or baseline clinical scores. At baseline, the group that received iliac crest bone graft had an increased percentage of patients who had multilevel fusions (32% versus 21%; p=0.033) and L5-S1 surgery (37% versus 26%; p=0.031) compared with the group without iliac crest autograft. Operative time was higher in the iliac crest bone-graft group (233.4 versus 200.9 minutes; p CONCLUSIONS: The outcome scores associated with the use of posterior iliac crest bone graft for lumbar spinal fusion were not significantly lower than those after fusion without iliac crest autograft. Conversely, iliac crest bone-grafting was not associated with an increase in the complication rates or rates of reoperation. On the basis of these results, surgeons may choose to use iliac crest bone graft on a case-by-case basis for lumbar spinal fusion

Chandra Observations of the Dwarf Nova WX Hyi in Quiescence

We report Chandra observations of the dwarf nova WX Hyi in quiescence. The X-ray spectrum displays strong and narrow emission lines of N, O, Mg, Ne, Si, S and Fe. The various ionization states implied by the lines suggest that the emission is produced within a flow spanning a wide temperature range, from T ~ 10^6 K to T >~ 10^8 K. Line diagnostics indicate that most of the radiation originates from a very dense region, with n ~ 10^{13}-10^{14} cm^{-3}. The Chandra data allow the first tests of specific models proposed in the literature for the X-ray emission in quiescent dwarf novae. We have computed the spectra for a set of models ranging from hot boundary layers, to hot settling flows solutions, to X-ray emitting coronae. WX Hyi differs from other dwarf novae observed at minimum in having much stronger low temperature lines, which prove difficult to fit with existing models, and possibly a very strong, broad O VII line, perhaps produced in a wind moving at a few x 10^3 km/s. The accretion rate inferred from the X-rays is lower than the value inferred from the UV. The presence of high-velocity mass ejection could account for this discrepancy while at the same time explaining the presence of the broad O VII line. If this interpretation is correct, it would provide the first detection of a wind from a dwarf nova in quiescence.Comment: accepted to ApJ; 19 pages, 3 figures, 1 tabl

Reactivation of herpes simplex virus type 1 is associated with cytomegalovirus and age

Recent studies have shown that Cytomegalovirus (CMV) may be an emerging marker of immunosenescence. CMV can affect the immune system by directly infecting leukocytes and hematopoietic cells or by eliciting an expansion of oligoclonal CD8+ T cells/contraction of the naïve T cell compartment that may reduce the host’s ability to fight other pathogens. To investigate further CMV-associated changes in immunity, a study was conducted with 1,454 adults (ages 25–91) to determine the association between CMV and reactivation of another latent herpesvirus, Herpes simplex virus type 1 (HSV-1), as indexed by antibody titers. Elevated antibody titers to latent HSV-1 were significantly associated with both CMV seropositivity and high CMV antibody levels. Evaluation by specific age groups (<45, 45–64, and 65+ years old) revealed that this association was detectable early in life (<45 years of age). Increases in HSV-1 antibodies by age occurred in CMV seropositive individuals but not CMV seronegative subjects. Within CMV seropositive subjects, increases in HSV-1 antibodies by age were only found in individuals with low CMV antibody levels as those with high CMV antibodies already exhibited elevated HSV-1 antibodies. These associations remained significant after accounting for body mass index, gender, and socioeconomic status. These results suggest that CMV can influence the immune response to another pathogen and support the concept that CMV may accelerate immunosenescence

Modeling the impact of the 13-valent pneumococcal conjugate vaccine serotype catch-up program using United States claims data

Background: Analysis of US claims data from April 2010 to June 2011 estimated that 39% of the 13-valent pneumococcal conjugate vaccine (PCV13) catch-up eligible cohort would ever receive the catch-up vaccination; a previous analysis assumed 87%. Methods: This updated figure was applied to a previously published 10-year Markov model while holding all other inputs constant. Results: Our model estimated that the catch-up program as currently implemented is estimated to prevent an additional 1.7 million cases of disease in children aged ≤59 months over a 10-year period, compared with routine PCV13 vaccination with no catch-up program. Conclusions: Because 39% catch-up uptake is less than the level of completion of the 4-dose primary PCV13 series, vaccine-preventable cases of pneumococcal disease and related deaths could be decreased further with additional uptake of catch-up vaccination in the catch-up eligible cohort