1,430 research outputs found

    In the Line of Fire: The Challenges of Managing Tourism Operations in the Victorian Alps

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    Understanding the impact of bushfires on tourism operations in Australian national parks and regional communities is of growing importance, with evidence of their increased frequency and severity linked, in part, to climate change. This is particularly critical for Australian alpine regions, given their greater emphasis on the summer season in the wake of lighter winter snowfalls. This article focuses on management issues and challenges of maintaining tourist operations within the Victorian Alps post-bushfire, including operator reactions to the bushfires and their subsequent implementation (or not) of crisis management and disaster recovery strategies. It is based on a qualitative study involving semistructured interviews with 13 tour operators based in the Mt. Buller and Alpine National Parks. Findings of this study suggest that the majority of operators will experience some impact on their business after the fires, albeit to different degrees, and point to a paucity of forward recovery planning. Operators expressed their concerns about prolonged negative media attention about the fires, but did not have strategies in place to deal with this issue proactively. There appears to be scope for assisting operators on the ground with disaster recovery, including the provision of more positive and timely media communication

    Control of Plasma Membrane Cl~ Fluxes in Chora corallina by External Cl~ and Light

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    ABSTRACT The efflux of Cl~ at the plasma membrane of Chara was studied in relation to two treatments known to affect the flux: that of removal of external Cl~ and of light. It is shown that although removal of external Cl~ results in a rapid reduction in Cl~ efflux (consistent with a direct effect of external ClÔ n the transport system) the magnitude of this reduction in the dark is greater than the measured dark influx. Therefore, in the dark at least, it is proposed that 1:1 exchange diffusion cannot account for the trans-stimulation of efflux by external Cl~. Light induces an inhibition of efflux and a concomitant stimulation of Cl~ influx at 20 °C, but at 10 °C the responses to light of the two fluxes can be separated temporally. It is therefore suggested that the fluxes are not reciprocally dependent on the same factor which mediates in the light response. Further considerations show that it is unlikely that the cytoplasmic Cl~ concentration mediates in the light response of either flux, but that changes in cytoplasmic pH may do so

    Transcriptional analysis of calcium-dependent and calcium-independent signalling pathways induced by oligogalacturonides

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    alpha-1,4-linked oligogalacturonides (OGs) are pectic fragments of plant cell walls that are able to induce defence and developmental responses. To understand plant responses to OGs at the transcriptional level, changes in gene expression were examined using oligonucleotide-based microarrays that cover almost the entire Arabidopsis transcriptome. In suspension-cultured Arabidopsis thaliana (L.) Columbia hypocotyl cells, approximately 4% of the total transcriptome exhibited significant change in abundance in response to treatment with OGs for 2 h. Steady-state changes in the abundance of transcripts encoding stress- and disease-related proteins, signalling components, and transcription factors were particularly noteworthy. As in other plant cell types, OGs elicit a rapid, but transient, elevation in cytosolic free Ca(2+). The Ca(2+) transient can be abolished by the protein kinase inhibitor 4,5,6,7-tetrabromobenzotriazole (TBB) and by the Ca(2+) channel inhibitor La(3+), thereby facilitating a distinction between Ca(2+)-dependent and -independent transcriptional responses. Among the 244 transcripts that were up-regulated by OGs, the response of 93 (38%) was selectively sensitive to abolition of the Ca(2+) transient. These OG-up-regulated, Ca(2+)-dependent transcripts included two noteworthy classes, the first comprising genes involved in cell wall modification following pathogen attack, and the second consisting of genes involved in the biosynthesis of jasmonate and C6 volatile compounds. These results support the notion of an important role for cytosolic Ca(2+) signalling in jasmonate biosynthesis following OG perception. Promoter analysis of OG-induced, inhibitor-sensitive and -insensitive genes identified several putative cis-elements that might be involved specifically in Ca(2+)-dependent transcriptional regulation

    The infrared compactness-temperature relation for quiescent and starburst galaxies

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    IRAS observations show the existence of a correlation between the infrared luminosity Lir and dust temperature Td in star-forming galaxies, in which larger Lir leads to higher dust temperature. The Lir-Td relation is commonly seen as reflecting the increase in dust temperature in galaxies with higher star formation rate. Even though the correlation shows a significant amount of dispersion, a unique relation has been commonly used to construct spectral energy distributions of galaxies in distant universe studies, such as source number counting or photometric redshift determination. In this work, we introduce a new parameter, namely the size of the star-forming region Rir and lay out the empirical and modelled relation between the global parameters Lir, Td and Rir of IR-bright non-AGN galaxies. IRAS 60-to-100um color is used as a proxy for the dust temperature and the 1.4GHz radio contiuum emission for the infrared spatial distribution. The analysis has been carried out on two samples. The first one is made of the galaxies from the 60um flux-limited IRAS Revised Bright Galaxy Samples which have a reliable RC size estimate from the VLA follow-ups of the IRAS Bright Galaxy Samples. The second is made of the sources from the 170um ISOPHOT Serendipity Sky Survey which are resolved by the NVSS or FIRST surveys. We show that the dispersion in the Lir-Td diagram can be reduced to a relation between the infrared surface brightness and the dust temperature, a relation that spans 5 orders of magnitude in surface brightness. We explored the physical processes giving rise to the Sir-Td relation, and show that it can be derived from the Schmidt law, which relates the star formation rate to the gas surface density.Comment: 13 pages, 7 figures, accepted for publication in A&

    Mid-infrared luminosity as an indicator of the total infrared luminosity of galaxies

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    The infrared (IR) emission plays a crucial role for understanding the star formation in galaxies hidden by dust. We first examined four estimators of the IR luminosity of galaxies, L_fir (Helou et al. 1988), L_tir (Dale et al. 2001), revised version of L_tir (Dale & Helou 2002) (we denote L_tir2), and L_ir (Sanders & Mirabel 1996) by using the observed SEDs of well-known galaxies. We found that L_ir provides excellent estimates of the total IR luminosity for a variety of galaxy SEDs. The performance of L_tir2 was also found to be very good. Using L_ir, we then statistically analyzed the IRAS PSCz galaxy sample (Saunders et al. 2000) and found useful formulae relating the MIR monochromatic luminosities [L(12um) and L(25um)], and L_ir. For this purpose we constructed a subsample of 1420 galaxies with all IRAS four band (12, 25, 60, and 100um) flux densities. We found linear relations between L_ir and MIR luminosities, L(12um) and L(25um). The prediction error with 95-% confidence level is a factor of 4-5. Hence, these formulae are useful for the estimation of the total IR luminosity only from 12um or 25um observations. We further tried to make an `interpolation' formula for galaxies at 0<z<1. For this purpose we construct the formula of the relation between 15-um luminosity and the total IR luminosity. We conclude that the 15-um formula can be used as an estimator of the total IR luminosity from 24um observation of galaxies at z \simeq 0.6.Comment: A&A in press, 8 pages, 9 figures, numerical errors correcte

    A controlled study of cold dust content in galaxies from z=0−2z=0-2

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    At z=1−3z=1-3, the formation of new stars is dominated by dusty galaxies whose far-IR emission indicates they contain colder dust than local galaxies of a similar luminosity. We explore the reasons for the evolving IR emission of similar galaxies over cosmic time using: 1) Local galaxies from GOALS (LIR=1011−1012 L⊙)(L_{\rm IR}=10^{11}-10^{12}\,L_\odot); 2) Galaxies at z∌0.1−0.5z\sim0.1-0.5 from the 5MUSES (LIR=1010−1012 L⊙L_{\rm IR}=10^{10}-10^{12}\,L_\odot); 3) IR luminous galaxies spanning z=0.5−3z=0.5-3 from GOODS and Spitzer xFLS (LIR>1011 L⊙L_{\rm IR}>10^{11}\,L_\odot). All samples have Spitzer mid-IR spectra, and Herschel and ground-based submillimeter imaging covering the full IR spectral energy distribution, allowing us to robustly measure LIRSFL_{\rm IR}^{\rm\scriptscriptstyle SF}, TdustT_{\rm dust}, and MdustM_{\rm dust} for every galaxy. Despite similar infrared luminosities, z>0.5z>0.5 dusty star forming galaxies have a factor of 5 higher dust masses and 5K colder temperatures. The increase in dust mass is linked with an increase in the gas fractions with redshift, and we do not observe a similar increase in stellar mass or star formation efficiency. L160SF/L70SFL_{160}^{\rm\scriptscriptstyle SF}/L_{70}^{\rm\scriptscriptstyle SF}, a proxy for TdustT_{\rm dust}, is strongly correlated with LIRSF/MdustL_{\rm IR}^{\rm\scriptscriptstyle SF}/M_{\rm dust} independently of redshift. We measure merger classification and galaxy size for a subsample, and there is no obvious correlation between these parameters and LIRSF/MdustL_{\rm IR}^{\rm \scriptscriptstyle SF}/M_{\rm dust} or L160SF/L70SFL_{160}^{\rm\scriptscriptstyle SF}/L_{70}^{\rm\scriptscriptstyle SF}. In dusty star forming galaxies, the change in LIRSF/MdustL_{\rm IR}^{\rm\scriptscriptstyle SF}/M_{\rm dust} can fully account for the observed colder dust temperatures, suggesting that any change in the spatial extent of the interstellar medium is a second order effect.Comment: Accepted for publication in ApJ. 21 pages, 11 figure

    Extinction risk of the world's freshwater mammals

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    The continued loss of freshwater habitats poses a significant threat to global biodiversity. We reviewed the extinction risk of 166 freshwater aquatic and semiaquatic mammals—a group rarely documented as a collective. We used the International Union for the Conservation of Nature Red List of Threatened Species categories as of December 2021 to determine extinction risk. Extinction risk was then compared among taxonomic groups, geographic areas, and biological traits. Thirty percent of all freshwater mammals were listed as threatened. Decreasing population trends were common (44.0%), including a greater rate of decline (3.6% in 20 years) than for mammals or freshwater species as a whole. Aquatic freshwater mammals were at a greater risk of extinction than semiaquatic freshwater mammals (95% CI –7.20 to –1.11). Twenty-nine species were data deficient or not evaluated. Large species (95% CI 0.01 to 0.03) with large dispersal distances (95% CI 0.03 to 0.15) had a higher risk of extinction than small species with small dispersal distances. The number of threatening processes associated with a species compounded their risk of extinction (95% CI 0.28 to 0.77). Hunting, land clearing for logging and agriculture, pollution, residential development, and habitat modification or destruction from dams and water management posed the greatest threats to these species. The basic life-history traits of many species were poorly known, highlighting the need for more research. Conservation of freshwater mammals requires a host of management actions centered around increased protection of riparian areas and more conscientious water management to aid the recovery of threatened species

    Technologies that assess the location of physical activity and sedentary behavior: a systematic review

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    Background: The location in which physical activity and sedentary behavior are performed can provide valuable behavioral information, both in isolation and synergistically with other areas of physical activity and sedentary behavior research. Global positioning systems (GPS) have been used in physical activity research to identify outdoor location; however, while GPS can receive signals in certain indoor environments, it is not able to provide room- or subroom-level location. On average, adults spend a high proportion of their time indoors. A measure of indoor location would, therefore, provide valuable behavioral information. Objective: This systematic review sought to identify and critique technology which has been or could be used to assess the location of physical activity and sedentary behavior. Methods: To identify published research papers, four electronic databases were searched using key terms built around behavior, technology, and location. To be eligible for inclusion, papers were required to be published in English and describe a wearable or portable technology or device capable of measuring location. Searches were performed up to February 4, 2015. This was supplemented by backward and forward reference searching. In an attempt to include novel devices which may not yet have made their way into the published research, searches were also performed using three Internet search engines. Specialized software was used to download search results and thus mitigate the potential pitfalls of changing search algorithms. Results: A total of 188 research papers met the inclusion criteria. Global positioning systems were the most widely used location technology in the published research, followed by wearable cameras, and radio-frequency identification. Internet search engines identified 81 global positioning systems, 35 real-time locating systems, and 21 wearable cameras. Real-time locating systems determine the indoor location of a wearable tag via the known location of reference nodes. Although the type of reference node and location determination method varies between manufacturers, Wi-Fi appears to be the most popular method. Conclusions: The addition of location information to existing measures of physical activity and sedentary behavior will provide important behavioral information

    Novel technology to help understand the context of physical activity and sedentary behaviour.

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    When used in large, national surveillance programmes, objective measurement tools provide prevalence estimates of low physical activity guideline compliance and high amounts of sedentary time. There are undoubtedly a plethora of reasons for this but one possible contributing factor is the current lack of behavioural context offered by accelerometers and posture sensors. Context includes information such as where the behaviour occurs, the type of activity being performed and is vital in allowing greater refinement of intervention strategies. Novel technologies are emerging with the potential to provide this information. Example data from three ongoing studies is used to illustrate the utility of these technologies. Study one assesses the concurrent validity of electrical energy monitoring and wearable cameras as measures of television viewing. This study found that on average the television is switched on for 202 min d(-1) but is visible in just 90 min of wearable camera images with a further 52 min where the participant is in their living room but the television is not visible in the image. Study two utilises indoor location monitoring to assess where older adult care home residents accumulate their sedentary time. This study found that residents were highly sedentary (sitting for an average of 720 min d(-1)) and spent the majority of their time in their own rooms with more time spent in communal areas in the morning than in the afternoon. Lastly, study three discusses the use of proximity sensors to quantify exposure to a height adjustable desk. These studies are example applications of this technology, with many other technologies available and applications possible. The adoption of these technologies will provide researchers with a more complete understanding of the behaviour than has previously been available
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