128 research outputs found

    Initial results from a GIS-based unsupervised classification study of the Martian surface

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    Maps of thermal inertia-albedo units and thermal inertia-elevation units on Mars’ surface have been generated by choosing thresholds that fit the strongest peaks in the histograms of these datasets. The units thus defined were then interpreted as distinct mixtures of materials on the surface, such as: bright fines, rock + bedrock and ice. We have conducted an initial classification of Thermal Emission Spectrometer (TES) night-time thermal inertia and TES albedo using a hard classifier. The methods used here are largely unsupervised and differ from those of previous studies. The aim of our study is to investigate what information can be obtained by utilising unsupervised classification algorithms to investigate the distribution of thermal materials on the surface of Mars. We find that unsupervised classification reveals additional structure in the clustering and spatial distribution of surface materials with moderate-low albedo and moderate-high thermal inertia. We highlight a number of regions such as Acidalia and Valles Marineris for future detailed studies of this type.National Committee for Space Science (NCSS), National Space Society of Australia (NSSA

    Epidemiology and geographical distribution of enteric protozoan infections in Sydney, Australia

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    © 2014 S. Fletcher et al., 2014. Results: Frequently detected protozoa were Blastocystis spp. (57%), Giardia intestinalis (27%) and Dientamoeba fragilis (12%). The age distribution showed that the prevalence of protozoa decreased with age up to 24 years but increasing with age from 25 years onwards. The geographic provenance of the patients indicates that the majority of cases of Blastocystis (53.1%) are clustered in and around the Sydney City Business District, while pockets of giardiasis were identified in regional/rural areas. The distribution of cases suggests higher risk of protozoan infection may exist for some communities.Conclusions: These findings provide useful information for policy makers to design and tailor interventions to target high risk communities Follow-up investigation into the risk factors for giardiasis in regional/rural areas is needed.Background: Enteric protozoa are associated with diarrhoeal illnesses in humans; however there are no recent studies on their epidemiology and geographical distribution in Australia. This study describes the epidemiology of enteric protozoa in the state of New South Wales and incorporates spatial analysis to describe their distribution.Design and methods: Laboratory and clinical records from four public hospitals in Sydney for 910 patients, who tested positive for enteric protozoa over the period January 2007 - December 2010, were identified, examined and analysed. We selected 580 cases which had residence post code data available, enabling us to examine the geographic distribution of patients, and reviewed the clinical data of 252 patients to examine possible links between protozoa, demographic and clinical features

    A Long Term ISU-UNISA Partnership: The SHSSP

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    Since 2011, the Southern Hemisphere Space Studies Program (SHSSP) has been held six times in Adelaide, Australia. The last program, which ran from January 9 to February 10, 2017, saw the engagement of 39 participants from around the world and over 45 international experts, whose backgrounds encompassed the entire spectrum of disciplines relevant to space exploration, industry and technology. The participants had a broad range of experiences, being represented by undergraduate students all the way to professionals employed in national space agencies, and entrepreneurs. This provided an exciting mix of motivations and abilities, which clearly epitomised the purpose of the program: to expose highly achieving students in training as well as accomplished professionals to a proxy of the multidisciplinary and multifaceted environment typical of space enterprises. The international, intercultural, and interdisciplinary philosophy of the program was reflected in a diversity of lectures, hands-on workshops, public events and team exercises, delivered by experts from Australia, America, Asia and Europe. A capstone project on the small satellite revolution involving participants, faculty and consulting experts, was synthesised in a paper entitled ‘Small Sats Big Shift: Recommendations for the Global South”. The 2017 program was highly successful, and the five week live-in program, complemented by one optional week of intensive English as second language program carried out before the commencement of the SHSSP, is now an established educational offering of the International Space University - University of South Australia (UniSA) consortium, which is presently exploring longer term agreements to continue and expand this productive educational collaboration beyond the next program, to be held at UniSA in January-February 2018

    Epidemiology and geographical distribution of enteric protozoan infections in Sydney, Australia

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    Background. Enteric protozoa are associated with diarrhoeal illnesses in humans; however there are no recent studies on their epidemiology and geographical distribution in Australia. This study describes the epidemiology of enteric protozoa in the state of New South Wales and incorporates spatial analysis to describe their distribution. Design and methods. Laboratory and clinical records from four public hospitals in Sydney for 910 patients, who tested positive for enteric protozoa over the period January 2007-December 2010, were identified, examined and analysed. We selected 580 cases which had residence post code data available, enabling us to examine the geographic distribution of patients, and reviewed the clinical data of 252 patients to examine possible links between protozoa, demographic and clinical features. Results. Frequently detected protozoa were Blastocystis spp. (57%), Giardia intestinalis (27%) and Dientamoeba fragilis (12%). The age distribution showed that the prevalence of protozoa decreased with age up to 24 years but increasing with age from 25 years onwards. The geographic provenance of the patients indicates that the majority of cases of Blastocystis (53.1%) are clustered in and around the Sydney City Business District, while pockets of giardiasis were identified in regional/rural areas. The distribution of cases suggests higher risk of protozoan infection may exist for some communities. Conclusions. These findings provide useful information for policy makers to design and tailor interventions to target high risk communities. Follow-up investigation into the risk factors for giardiasis in regional/rural area is needed

    An Analysis of MARSIS Radar Flash Memory Data from Lunae Planum, Mars: Searching for Subsurface Structures

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    Lunae Planum is a Martian plain measuring approximately 1000 km in width and 2000 km in length, centered at coordinates 294°E-11°N. MOLA elevations range from +2500 m to +500 m in the south, gently sloping northward to -500 m. The plain is part of a belt of terrains located between the southern highlands and the northern lowlands, that are transitional in character (e.g., by elevation, age and morphology). These transitional terrains are poorly understood, in part because of their relative lack of major geomorphological features. They record however a very significant part of Mars's geologic history. The most evident features on Lunae Planum's Hesperian surface are regularly spaced, longitudinally striking, wrinkle ridges. These indicate the presence of blind thrust faults cutting through thick stacks of layers of volcanic or sedimentary rocks. The presence of fluidized ejecta craters scattered all over the region suggests also the presence of ice or volatiles in the subsurface. In a preliminary study of Lunae Planum's subsurface we used the Mars Express ground penetrating radar MARSIS dataset [1], in order to detect reflectors that could indicate the presence of fault planes or layering. Standard radargrams however, provided no evidence of changes in value of dielectric constant that could indicate possible geologic discontinuities or stratification of physically diverse materials. We thus started a new investigation based on processing of raw MARSIS data. Here we report on the preliminary results of this study. We searched the MARSIS archive for raw data stored in flash memory. When operating with flash storage, the radar collects 2 frequency bands along-track covering a distance = 100-250 km, depending on the orbiter altitude [2]. We found flash memory data from 24 orbits over the area. We processed the data focusing radar returns in off-nadir directions, to maximize the likelihood of detecting sloping subsurface structures, including those striking parallel to the Mars Express sub-polar orbits. We plan to follow this study by applying a new processor aimed at improving the resolution and signal to noise ratio of the data. [1] Caprarelli et al. (2017), LPSC 48, 1720. [2] Watters et al. (2017), LPSC 48, 1693

    Subsurface properties of Lucus Planum, Mars, as seen by MARSIS

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    Lucus Planum, extending for a radius of approximately 500 km around 181°E, 5°S, is part of the Medusae Fossae Formation (MFF), a set of several discontinuous deposits of fine-grained, friable material straddling across the Martian highland-lowland boundary. Parts of the MFF have been probed through radar sounding by MARSIS and SHARAD, synthetic-aperture, low-frequency radars carried respectively by ESA's Mars Express and NASA's Mars Reconnaissance Orbiter. They transmit low-frequency radar pulses that are capable of penetrating below the surface, and are reflected by any dielectric discontinuity present in the subsurface. The dielectric permittivity of the MFF material, estimated from data of both radars, is consistent with either a substantial component of water ice or a low-density, ice-poor material. There is no evidence for internal layering in SHARAD data, despite the fact that layering at scales of tens of meters has been reported in many parts of the MFF. This lack of detection can be the result of one or more factors, such as high interface roughness, low dielectric contrast between materials, or discontinuity of the layers. After more than 10 years of observations, MARSIS has acquired about 240 orbits across Lucus Planum, making it possible to map the presence and depth of subsurface interfaces to a much greater detail than in previous works. The positions and strengths of subsurface echoes were extracted manually from radargrams and mapped across Lucus Planum, converting echo time delay to apparent depth. The strongest subsurface echoes, resulting from weak internal attenuation, strong subsurface reflectivity, or both, are found within the deposits located NW of Apollinaris Patera, while no subsurface echoes could be detected in the central section of Lucus Planum, in spite of several high-SNR observations. Subsurface reflections are common in the Eastern and Northwestern sectors, in some cases to depths of more than 2000 m assuming a dielectric permittivity of about 3. The lack of subsurface reflections in the central part of Lucus Planum can be the result of several factors, some of which depend on surface properties. A high topographic roughness at scales comparable to the radar wavelength causes scattering of the impinging pulse, resulting in weaker surface and subsurface echoes. However, surface roughness estimated from MOLA data is higher in the Eastern part of Lucus Planum. Another possibility is that roughness at the base of the deposit is higher in its central part, although there is no indication of such kind of trend in the older surrounding terrains. Because subsurface echoes appear to be closely associated with areas of distinct surface morphology, it is possible that Lucus Planum is in fact laterally inhomogeneous and that the central part consists of denser, more radar-attenuating material. This work was supported by the Italian Space Agency (ASI) through contract no. I/032/12/1

    Spatial analysis of myocardial infarction in Iran: National report from the Iranian myocardial infarction registry

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    Background: Myocardial infarction (MI) is a leading cause of mortality and morbidity in Iran. No spatial analysis of MI has been conducted to date. The present study was conducted to determine the pattern of MI incidence and to identify the associated factors in Iran by province. Materials and Methods: This study has two parts. One part is prospective and hospital-based, and the other part is an ecological study. In this study, the data of 20,750 new MI cases registered in Iranian Myocardial Infarction Registry in 2012 were used. For spatial analysis in global and local, spatial autocorrelation, Moran's I, Getis-Ord, and logistic regression models were used. Data were analyzed by Stata software and ArcGIS 9.3. Results: Based on autocorrelation coefficient, a specific pattern was observed in the distribution of MI incidence in different provinces (Moran's I:0.75, P < 0.001). Spatial pattern of incidence was approximately the same in men and women. MI incidence was clustering in six provinces (North Khorasan, Yazd, Kerman, Semnan, Golestan, and Mazandaran). Out of the associated factors with clustered MI in six provinces, temperature, humidity, hypertension, smoking, and body mass index (BMI) could be mentioned. Hypertension, smoking, and BMI contributed to clustering with, respectively, 2.36, 1.31, and 1.31 odds ratio. Conclusion: Addressing the place-based pattern of incidence and clarifying their epidemiologic dimension, including spatial analysis, has not yet been implemented in Iran. Report on MI incidence rate by place and formal borders is useful and is used in the planning and prioritization in different levels of health system

    Radar Sounding by MARSIS Over Lucus Planum, Mars

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    Probed by the MARSIS radar sounder, Lucus Planum is found to be laterally inhomogeneous, its central part consisting of denser, more radar-attenuating material
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