2,146 research outputs found

    EFFECT OF RECREATIONAL TRAIL TRAFFIC LEVEL ON EASTERN RED-BACKED SALAMANDER (PLETHODON CINEREUS) RELATIVE ABUNDANCE

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    The effects of roads and trails on terrestrial salamanders, primarily plethodontids, can be important. The abundance of terrestrial salamanders often increases with distance from roads. Less is known about the effects of recreational or hiking trails on terrestrial salamanders than is known about the effects of roads. We explored how low and high traffic trails in a suburban biological reserve affect the relative abundance of Eastern Red-backed Salamanders (Plethodon cinereus). We found more salamanders under cover objects next to low traffic trails compared to either high traffic trails or wooded areas without trails. At wooded sites, we found only striped morphs whereas at high traffic sites we found only unstriped morphs. Low traffic sites included a range of color morph frequencies. The proportion of females found in each site did not differ, nor did the mean size of the salamanders. Our results suggest that the impact of recreational walking trails needs to be examined more closely to see how and why the distributions of P. cinereus, and potentially other woodland salamanders, are affected and what trail characteristics are important in driving the apparent effects. Such information will contribute to the design and maintenance of walking trails in natural areas that minimize effects on terrestrial salamanders, and likely other organisms

    Long slit spectroscopy of NH2 in comets Halley, Wilson, and Nishikawa-Takamizawa-Tago

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    Long-slit spectra of comets Halley, Wilson and Nishikawa-Takamizawa-Tago were obtained with the 3.9 meter Anglo-Australian Telescope. Spectra of comets Halley and Wilson were obtained with the IPCS at a spectral resolution of 0.5 A and a spatial resolution of 10(exp 3) km. Spectra of comets Wilson and Nishikawa-Takamizawa-Tago were obtained with a CCD at a spectral resolution of 1.5 A and a spatial resolution of approximately 3 x 10(exp 3) km. Surface brightness profiles for NH2 were extracted from the long-slit spectra of each comet. The observed surface brightness profiles extend along the slit to approximately 6 x 10(exp 4) km from the nucleus in both sunward and tailward directions. By comparing surface distribution calculated from an appropriate coma model with observed surface brightness distributions, the photodissociation timescale of the parent molecule of NH2 can be inferred. The observed NH2 surface brightness profiles in all three comets compares well with a surface brightness profile calculated using the vectorial model, an NH3 photodissociation timescale of 7 x 10(exp 3) seconds, and an NH2 photodissociation timescale of 34,000 seconds

    Integrated aircraft scheduling problem: An auto-adapting algorithm to find robust aircraft assignments for large flight plans

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    The overall airline scheduling process involves hierarchical steps starting with the network design and ending with crew assignment. Aircraft routing is especially important with respect to timing and costs for an airline. In this contribution, we focus on aircraft routing where aircraft are assigned to flight legs further considering maintenance requirements. We developed and implemented algorithms that extend the aircraft routing problem (ARP) by including profit and robustness. The latter objective is important as the dependencies of flights and airlines increases and deviations to the original time plan as unexpected events like volcano eruptions or heavy weather-related issues are difficult to handle. A robust aircraft routing ensures that unforeseen events have less impact. The results are compared to current state-of-the-art solutions. We developed a test instance-generator to create specific problems and build a library for future benchmarking tests

    CO Line Emission and Absorption from the HL Tau Disk: Where is all the dust?

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    We present high-resolution infrared spectra of HL Tau, a heavily embedded young star. The spectra exhibit broad emission lines of hot CO gas as well as narrow absorption lines of cold CO gas. The column density for this cooler material (7.5+/-0.2 x 10^18 cm-2) indicates a large column of absorbing gas along the line of sight. In dense interstellar clouds, this column density of CO gas is associated with Av~52 magnitudes. However, the extinction toward this source (Av~23) suggests that there is less dust along the line of sight than inferred from the CO absorption data. We discuss three possibilities for the apparent paucity of dust along the line of sight through the flared disk: 1) the dust extinction has been underestimated due to differences in circumstellar grain properties, such as grain agglomeration; 2) the effect of scattering has been underestimated and the actual extinction is much higher; or (3) the line of sight through the disk is probing a gas-rich, dust-depleted region, possibly due to the stratification of gas and dust in a pre-planetary disk.Comment: To be published in The Astrophysical Journa

    Maintaining Oral Health with Parkinson’s disease and Arthritis.

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    PosterObjective: The objective of this case presentation is to discuss the modifications of dental care for a patient with Parkinson’s disease. Background: A 72 year old Caucasian male presented to the dental hygiene clinic for a periodontal maintenance appointment. Significant findings in the medical history include current treatment of Parkinson’s disease, arthritis in the hands and feet, and medications Omeprazole, Fluoxetine, Gemfibrozil, Gabapentin, Levodopa, and Clonazepam. Assessment: Patient presents with generalized moderate plaque induced gingivitis evidenced by reddish-pink gingiva, 60% BOP, bulbous, spongy papillae. Clinically the patient presented with generalized 4-8mm clinical attachment levels. Radiographically, the patient presented with generalized mild to moderate bone loss evidenced by 3-5mm from the CEJ. The primary contributing factor to the gingival inflammation was the plaque score of 97%. The patient struggles with oral hygiene due to his Parkinson’s disease and arthritis in hands. DH Care Plan: patient received full mouth debridement, instruction on a modified floss holder with clay, product recommendations of xylitol gum and toothpaste to reduce xerostomia. Results: Oral health indicators from previous appointments showed minimal or no improvements due to the patient’s medical condition. Conclusions: Since last recall a few sites had improved including probing depths by 1-2mm. Patient was referred to a comprehensive care clinic for extraction of tooth number four, and an implant is treatment planned for replacement. It is recommended that the patient continue on 3 month intervals to monitor his oral health status and identify dental disease earl

    Phenotypic plasticity's role in the origins and diversification of feeding strategies in spadefoot toad larvae

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    Phenotypic plasticity - the ability of one genotype to produce many phenotypes in response to environmental change - may play a critical role in allowing populations to endure environmental transitions. Moreover, selection on genetic variation underlying plastic phenotypes may modify and refine these traits such that they are adaptive in novel environments. Yet the prevalence of such genetic variation in natural populations, and the proximate mechanisms underlying its expression, remain relatively uncharacterized. My research sought to address this gap by assessing the role of environmentally-dependent phenotypes and their underlying genetic variation in the origins and diversification of feeding strategies among spadefoot toad larvae. While most spadefoot larvae feed on a range of diets, two lineages specialize on specific resources. Tadpoles of the genus Spea can develop as a carnivore morph that preys on, and is induced by fairy shrimp. In contrast, Sc. couchii, which cooccurs with Spea, specializes on detritus. Using a comparative approach, I determined that Sc. couchii have been excluded from the shrimp resource because of predation pressure imposed by Spea, and that Sc. couchii minimize this predation risk via behavioral plasticity. Furthermore, this dietary exclusion has been followed by evolutionary modification of Sc. couchii's behavioral, physiological and morphological responses to shrimp. Relaxed selection on traits that are no longer used - such as those involved with consuming shrimp in Sc. couchii - can result in the accumulation of neutral population genetic variation. When these populations encounter a new environment (or revisit an old one), such genetic variation may be expressed and is potentially adaptive. I found that feeding Sc. couchii shrimp amplifies the expression of genetic variation in a trait that is adaptive for consuming shrimp (as seen in Spea). Additionally, the hormone corticosterone, which is elevated in Sc. couchii fed the shrimp diet, can mediate the expression of this variation. In summary, ecological interactions can influence genetic variation underlying environmentally-dependent phenotypes and, by extension, phenotypes that are expressed and potentially adaptive when populations transition to novel environments. Furthermore, characterizing environmentally-dependent physiological processes may help us to better understand when and how such phenotypes are expressed

    Comet outbursts and polymers of HCN

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    Dramatic cometary outbursts have been noted by observers for many years. These outbursts can sometimes increase the apparent brightness of a comet up to 9 mag and release energy on the order of 10 exp 19 ergs. A number of mechanisms have been suggested for outburst activity; however, none has been generally accepted. HCN is a known constituent of both interstellar icy grain mantles and cometary nuclei, and HCN polymers have been postulated to exist on the dark surface of comets such as P/Halley. Since polymerization is a strongly exothermic process, we investigate the possibility that HCN polymerization can provide the energy needed for outbursts. Polymerization may be continuing in the inhomogeneous interior of comets. In addition, the reactive CN groups in these oligomers can be hydrolyzed and may contribute to CO2 and CO pressure buildup in the interior of comets
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