106 results on '"Spectrum analysis"'
Search Results
2. Comparison of the Analysis of Respirable Crystalline Silica in Workplace Air by Direct-on-Filter Methods using X-ray Diffraction and Fourier Transform Infrared Spectroscopy.
- Author
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Ichikawa, Akemi, Volpato, John, O'Donnell, Gregory E, and Mazereeuw, Martin
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AIR pollution , *X-rays , *DUST , *OCCUPATIONAL exposure , *COMPARATIVE studies , *FILTERS & filtration , *SILICA , *SPECTRUM analysis - Abstract
A comparison of the analysis of respirable crystalline silica direct-on-filter methods using X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy was undertaken using 253 real workplace air samples from road construction and tunnelling, coal mining, and kitchen benchtop manufacturing in Australia. Using pure α-quartz standards, XRD and FT-IR direct-on-filter analyses produced identical test results, however, the real workplace samples showed a clear discrepancy between FT-IR and XRD results with on average a 9% positive bias of the FT-IR results. The cause of the positive bias was due to matrix interferences which was confirmed by using synthetic mixture air samples. Approximately a third of the data by direct-on-filter method using FT-IR was assessed to be invalid based on the peak height ratio criterion due to excessive interferences and weight overload limitations. The XRD method showed better results due to less interference from the common matrices. XRD could handle up to twice the sample loading and at higher loadings up to 7 mg when a correction was applied. It was also able to achieve a lower limit of detection of 2 µg filter−1 when a slower scan condition was utilized. [ABSTRACT FROM AUTHOR]
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- 2022
- Full Text
- View/download PDF
3. Should TV move?
- Author
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Tanner, Giles and Given, Jock
- Published
- 2020
4. 利用GPS 和GRACE 研究澳大利亚地壳垂向 季节性变化.
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汪浩, 岳建平, and 向云飞
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ROOT-mean-squares , *SIGNAL reconstruction , *WATER storage , *SPECTRUM analysis , *GLOBAL Positioning System - Abstract
Objectives: There are obvious seasonal variations in the GPS height time series, which affect the improvement of precision and can be corrected by both mathematical modelling and geophysical mechanisms. Compared to least square fitting, singular spectrum analysis (SSA) can extract random seasonal signals effectively through signal reconstruction, which is unaffected by the assumed sinusoidal waves. According to the elastic loading theory, the gravity recovery and climate experiment (GRACE) can be used to calculate the vertical surface displacement caused by changes in terrestrial water storage. Methods: This paper mainly studies the feasibility of correcting the seasonal variations in GPS heights using SSA and GRACE inversion results. The height time series of 27 GPS stations in Australia with a time span of from 5 to 10 years were chosen and combined with GRACE simultaneous inversions. Results: Because the spatial resolutions of GRACE are coarse and the loading displacement is much more sensitive to near‑field mass changes than far‑field ones, the amplitudes of GRACE ‑inferred hydrological loading deformations are significantly smaller than GPS. The weighted root mean square (WRMS) are reduced at 22 stations after GRACE ‑inferred displacement corrections, and the correlation coefficients between deformations estimated by GPS and GRACE range from 0.12 to 0.78 with a mean value of 0.43, indicating that GPS and GRACE results have good consistency and correlation. SSA is used to extract the annual signals of vertical displacements derived from GPS and GRACE, and contribution rates of singular spectral variance of annual signals are 21.60% and 34.48%, respectively, expressing that annual signals are the main components of GRACE inferred results. Geographical climatic conditions have a significant impact on the consistency of annual signals derived from GPS and GRACE. Compared with the arid areas in central and western Australia, the amplitude and phase of annual signals derived from GPS and GRACE are more consistent in the northern region with seasonal rainfall. Furthermore, cross wavelet transform (XWT) finds that the vertical displacement series derived from GPS and GRACE of each station have a significant resonance period of one year. The circular average phase angles of GPS/GRACE at the period closet to 1 cycle per year (cpy) outside the cone of influence range from − 74.03° to 67.23° . The mean XWT ‑ based semblances range from 0.28 to 0.99 with an average value of 0.79, showing that there is a significant positive correlation between the annual variations derived from GPS and GRACE. Conclusions: Overall, GRACE‑inferred deformations can explain the annual variations of GPS‑derived displacements, particularly in areas with high hydrological loading. It is possible to correct the annual signals of GPS heights by GRACE inversions, but the effect is not as good as the SSA‑filtered annual signals. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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5. Effectiveness of bioimpedance spectroscopy on dry weight (DW) measurement in haemodialysis patients: A systematic review
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Ko, Hyeyoung, Jayasekara, Rasika, and Grech, Carol
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- 2019
6. Not your grandfather's HAM radio
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Wait, Phil
- Published
- 2015
7. Energy and angular distribution of positrons re-emitted from W(100)
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AIP ACOFT 2012 Conference (2012 : Sydney), Sudarshan, K, Samarin, SN, Guagliardo, P, Petrov, VN, Weiss, AH, and Williams, JF
- Published
- 2012
8. Intake of specific types of fruit and vegetables is associated with higher levels of skin yellowness in young women: A cross-sectional study.
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Coyle, Daisy H, Pezdirc, Kristine, Hutchesson, Melinda J, and Collins, Clare E
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APPLES , *BROCCOLI , *HUMAN skin color , *CORN , *FRUIT , *INGESTION , *PEARS , *QUESTIONNAIRES , *SOYBEAN , *SPECTRUM analysis , *SPINACH , *VEGETABLES , *MULTIPLE regression analysis , *CROSS-sectional method , *BETA carotene - Abstract
Carotenoids are fat-soluble pigments primarily found in fruits and vegetables. They accumulate in human skin and contribute to skin yellowness, which has a favorable effect on appearance. The association between specific fruit and vegetable intakes and skin yellowness is currently unknown and could help to promote increased fruit and vegetable consumption in those motivated by appearance, such as young women. The objective was to evaluate associations between specific fruit and vegetable intakes and skin yellowness in young women. It was hypothesized that the intake of fruits and vegetables known to be rich in carotenoids, particularly β-carotene, would account for the greatest variation in skin yellowness. One hundred and eighteen women (18–40 years) were recruited from the Hunter region, NSW, Australia. Fruit and vegetable intakes were assessed using the 2010 Australian Eating Survey Food Frequency Questionnaire and skin yellowness was measured using reflectance spectroscopy. Multiple linear regression was used to assess how much of the variation in skin yellowness is explained by fruit and vegetable intakes. Higher combined fruit and vegetable intake ( P = .0004) and higher total fruit intake ( P = .005) were associated with increased skin yellowness. Three specific fruits (apple/pear, mango/pawpaw and dried fruit) and five vegetables (beans/lentils, spinach, broccoli, corn, baked beans) also accounted for a significant proportion of the variation in skin yellowness ( P < .05). In conclusion, the consumption of eight specific fruits and vegetables and total combined fruit and vegetable intake are positively associated with skin yellowness and this confers a desirable effect on appearance. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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9. Pursuing sesterterpene lactams in Australian Irciniidae sponges.
- Author
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Prasad, Pritesh, Zhang, Ailian, Salim, Angela A., and Capon, Robert J.
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ORGANIC compound analysis , *ALTERNATIVE medicine , *PHYSICAL & theoretical chemistry , *INVERTEBRATES , *SPECTRUM analysis - Abstract
Chemical investigation of two Irciniidae sponges collected by hand (SCUBA) from Australian near shore waters, afforded six new examples of a rare class of sesterterpene lactam; ircinialactams B ( 1 ), G ( 2 ), H ( 5 ), and I ( 6 ), and 8-hydroxyircinialactams C ( 3 ) and G ( 4 ); together with the new biosynthetically related lactone, ircinialactone A ( 7 ). Also isolated were seven biosynthetically related known Irciniidae metabolites; ircinialactams A ( 8 ) and C ( 9 ), (7 E ,12 E ,20 Z ,18 S )-variabilin ( 10 ), (7 Z ,12 Z ,20 Z ,18 S )-variabilin ( 11 ), (7 E ,12 Z ,20 Z ,18 S )-variabilin ( 12 ), (7 Z ,12 E ,20 Z ,18 S )-variabilin ( 13 ) and irciniafuran A ( 14 ). The structure elucidation of 1 – 14 was achieved by detailed spectroscopic analysis, and consideration of a plausible biosynthetic relationship linking Irciniidae sesterterpene β-furans, lactams and lactones. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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10. WAVEGEN - a Hindcast Wave Model for Varying Water Depths
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Australasian Port and Harbour Conference (7th: 1999: Perth, W.A.) and Searle, Peter
- Published
- 1999
11. Analysis of sea level fluctuations around the Australian coast with anomaly time series analysis approach.
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Dehghan, Yaser, Amini Zenooz, Seyyed Mahdi, and Pour, Zahra Fazilat
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SEA level , *FOURIER transforms , *WATER levels , *HILBERT-Huang transform , *COASTS , *SPECTRUM analysis , *TIME series analysis - Abstract
Thirty two-year observations (1990–2022) of water level from a total of 14 high-quality acoustic tide stations around the coast of Australia deployed for the Australian Baseline Sea Level Monitoring Project were analyzed. The following three approaches were used: Fourier Transform (FT), Empirical Mode Decomposition (EMD), and Singular Spectrum Analysis (SSA). The water level anomaly was observed to have predominant annual variations with a period of about 12 months based on the Fourier transform. The intrinsic components of stations were extracted in the EMD analysis and the mean period of each of the components was calculated using the zero down crossing method. A regular association was observed between the order of modes and the mean period such that the periods increase by a factor of two on successive modes. The third method used for anomaly analysis was SSA. The number of the obtained components in this method was less than in the EMD. Moreover, the order observed for the components' period in the EMD was not seen in this method. Spectral analysis of Autocorrelation function (ACF) has demonstrated that peak frequencies are almost the same with anomaly spectra so the dominant modes in anomalies are also present in the ACF. • More than 30-year sea level data around the Australian coast have been analyzed. • Fourier Transform, Empirical Mode Decomposition, and Singular Spectrum Analysis have been used. • A predominant annual variation with a period of about 12 months was observed based on the Fourier transform. ACF analysis showed that: ✓ The periodic and regular signals have larger ACF with low rate decreasing amplitude. ✓ Irregular signal has a smaller ACF and its amplitude decreases more sever. ✓ In general, the more regular the time series, the more symmetrical its ACF. ✓ Spectral analysis of anomalies and ACF has demonstrated that peak frequencies are almost the same in both spectra. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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12. Cryptocaryoic acids A – C: New phenyl alkyl acids isolated from the leaves of Australian rainforest plant Cryptocarya mackinnoniana.
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Raju, Ritesh, Gunawardena, Dhanushka, Reddell, Paul, and Münch, Gerald
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ANTI-inflammatory agents , *MACROPHAGES , *PHYTOCHEMICALS , *INTERFERONS , *LEAVES , *TUMOR necrosis factors , *NATURE , *NITRIC oxide , *SPECTRUM analysis , *PHARMACODYNAMICS - Abstract
Phytochemical investigation of the leaves of the Australian rainforest tree Cryptocarya mackinnoniana led to the discovery of three new oxygenated phenyl alkyl acids, cryptocaryoic acids A – C and two known compounds, cryptocaryone and 2′,6′-dihydroxy-4′-methoxychalcone. The structures of all the compounds were determined by detailed spectroscopic analysis. Mosher's analysis was used for absolute stereochemistry determination at C-11, while the remaining stereochemistry determination of the one remaining stereocenter C-13 was based on NOESY correlations. All compounds isolated were also evaluated for their anti-inflammatory properties by assessing their inhibitory effects on LPS and interferon-γ induced nitric oxide (NO) production and TNF- α release in RAW 264.7 macrophages. The new cryptocaryoic acids exhibited weak to moderate anti-inflammatory activity (NO inhibition) ranging from (18.4–56 μM). [Display omitted] • Three new phenyl alkyl acids, cryptocaryoic acids A – C, were isolated from the leaves of Cryptocarya mackinnoniana • Cryptocaryoic acids exhibited weak to moderate anti-inflammatory activity • Cryptocaryoic acids are the first in the series of molecules bearing the phenyl oxy-alkyl acid from C.mackinnoniana [ABSTRACT FROM AUTHOR]
- Published
- 2022
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13. Wollamides: Antimycobacterial Cyclic Hexapeptidesfrom an Australian Soil Streptomyces.
- Author
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Khalil, Zeinab G., Salim, Angela A., Lacey, Ernest, Blumenthal, Antje, and Capon, Robert J.
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AMIDES , *ANTIBACTERIAL agents , *HEXAPEPTIDES , *STREPTOMYCES , *MYCOBACTERIA , *SPECTRUM analysis - Abstract
A soil Streptomycesnov. sp. (MST-115088) isolatedfrom semiarid terrain near Wollogorang Station, Queensland, returnedtwo known and two new examples of a rare class of cyclic hexapeptide,desotamides A and B (1and 2) and E andF (3and 4), respectively, together withtwo new d-Orn homologues, wollamides A and B (5and 6). Structures were assigned by detailed spectroscopicand C3Marfey’s analysis. The desotamides/wollamidesexhibit growth inhibitory activity against Gram-positive bacteria(IC500.6–7 μM) and are noncytotoxic to mammaliancells (IC50>30 μM). The wollamides exhibit antimycobacterialactivity (IC502.8 and 3.1 μM), including reductionin the intracellular mycobacterial survival in murine bone marrow-derivedmacrophages. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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14. The New Maia Detector System: Methods For High Definition Trace Element Imaging Of Natural Material.
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Ryan, C. G., Siddons, D. P., Kirkham, R., Dunn, P. A., Kuczewski, A., Moorhead, G., De Geronimo, G., Paterson, D. J., de Jonge, M. D., Hough, R. M., Lintern, M. J., Howard, D. L., Kappen, P., and Cleverley, J.
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IMAGING systems , *TRACE elements , *DECONVOLUTION (Mathematics) , *SPECTRUM analysis , *DETECTORS - Abstract
Motivated by the need for megapixel high definition trace element imaging to capture intricate detail in natural material, together with faster acquisition and improved counting statistics in elemental imaging, a large energy-dispersive detector array called Maia has been developed by CSIRO and BNL for SXRF imaging on the XFM beamline at the Australian Synchrotron. A 96 detector prototype demonstrated the capacity of the system for real-time deconvolution of complex spectral data using an embedded implementation of the Dynamic Analysis method and acquiring highly detailed images up to 77 M pixels spanning large areas of complex mineral sample sections. [ABSTRACT FROM AUTHOR]
- Published
- 2010
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15. Body composition following stem cell transplant: Comparison of bioimpedance and air-displacement plethysmography.
- Author
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Yun-Chi Hung, Bauer, Judith D., Horsely, Pamela, Ward, Leigh C., Bashford, John, and Isenring, Elisabeth A.
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BODY composition , *CONFIDENCE intervals , *HEMATOPOIETIC stem cell transplantation , *PLETHYSMOGRAPHY , *RESEARCH funding , *SPECTRUM analysis , *BODY mass index , *DATA analysis software , *DESCRIPTIVE statistics , *PHOTON absorptiometry , *ODDS ratio - Abstract
Objective: The aim of this study was to assess the agreement between detected changes in body composition determined by bioimpedance spectroscopy (BIS) and air-displacement plethysmography (ADP) among patients with cancer undergoing peripheral blood stem cell transplantation (PBSCT); and to assess the agreement of absolute values of BIS with ADP and dual energy x-ray (DXA). Methods: Forty-four adult hematologic cancer patients undergoing PBSCT completed both BIS and ADP assessment at preadmission and at 3 mo after transplantation. A subsample (n = 11) was assessed by DXA at 3 mo after transplantation. Results were examined for the BIS instrument's default setting and three alternative predictive equations from the literature. Agreement was assessed by the Bland-Altman limits of agreement analysis while correlation was examined using the Lin's concordance correlation. Results: Changes in body composition parameters assessed by BIS were comparable with those determined by ADP regardless of the predictive equations used. Bias of change in fat-free mass was clinically acceptable (all <1 kg), although limits of agreement were wide (more than ±6 kg). Overall, the BIS predictive equation accounting for body mass index performed the best. Absolute body composition parameters predicted by the alternative predictive equations agreed with DXA and ADP better than the BIS instrument's default setting. Conclusion: Changes predicted by BIS were similar to those determined by ADP on a group level; however, agreement of predicted changes at an individual level should be interpreted with caution due to wide limits of agreement. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
16. Anti-staphylococcal activity of C-methyl flavanones from propolis of Australian stingless bees (Tetragonula carbonaria) and fruit resins of Corymbia torelliana (Myrtaceae).
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Massaro, C.F., Katouli, M., Grkovic, T., Vu, H., Quinn, R.J., Heard, T.A., Carvalho, C., Manley-Harris, M., Wallace, H.M., and Brooks, P.
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MEDICINAL plants , *ALTERNATIVE medicine , *ANTI-infective agents , *FLAVONOIDS , *FRUIT , *GUMS & resins , *MASS spectrometry , *MICROBIAL sensitivity tests , *NUCLEAR magnetic resonance spectroscopy , *PSEUDOMONAS , *SPECTRUM analysis , *STAPHYLOCOCCUS aureus , *DESCRIPTIVE statistics , *FLAVANONES , *IN vitro studies , *PHARMACODYNAMICS - Abstract
Abstract: Propolis of Australian stingless bees (Tetragonula carbonaria, Meliponini) originating from Corymbia torelliana (Myrtaceae) fruit resins was tested for its antimicrobial activities as well as its flavonoid contents. This study aimed at the isolation, structural elucidation and antibacterial testing of flavanones of C. torelliana fruit resins that are incorporated into stingless bee propolis. Flavanones of this study were elucidated by spectroscopic and spectrometric methods including UV, 1D and 2D NMR, EI-MS, ESI-MS and HR-MS. The results indicated known C-methylated flavanones namely, 1 (2S)-cryptostrobin, its regioisomer 2 (2S)- stroboponin, 3 (2S)- cryptostrobin 7-methyl ether, and 6 (2S)- desmethoxymatteucinol, and known flavanones 4 (2S)- pinostrobin and 5 (2S)- pinocembrin as markers for C. torelliana fruit resins and one propolis type. Ethanolic preparations of propolis were shown to be active against Staphylococcus aureus (ATCC 25923) and to a lesser extent against Pseudomonas aeruginosa (ATCC 27853). C. torelliana flavanones inhibited the growth of S. aureus therefore contributing to the antibacterial effects observed for Australian stingless bee propolis extracts. [Copyright &y& Elsevier]
- Published
- 2014
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17. The effects of endmember selection on modelling impervious surfaces using spectral mixture analysis: a case study in Sydney, Australia.
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Jacobson, Carol R.
- Subjects
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CITIES & towns , *LAND cover , *IMAGE processing , *PIXELS , *MATHEMATICAL models , *VEGETATION & climate , *SPECTRUM analysis - Abstract
In urban areas, spectral mixture analysis (SMA) is a common technique for deriving the fractions of land covers within a pixel and information on the distribution of impervious surfaces. This study examined how the selection of endmembers affected the quantification of impervious surfaces using TM and ASTER imagery. Multiple subsets of endmembers derived using (1) extreme pixels from a minimum noise fraction (MNF) transformation, and (2) a manual approach usinga prioriknowledge of the study area were analysed. Two data sets were used to assess accuracy: (1) simulated image data comprising unmixed and mixed pixels of 10 typical and spectrally different urban land covers, and (2) detailed data derived from high-resolution aerial photography. The dimensionality of the imagery limited the number of endmembers, and as a result, unmixed land covers were modelled using multiple endmembers and some cells had abundance values that summed to more than one or were negative. The land covers of red roofs and concrete were the largest contributors to the error in impervious surfaces. The Sequential Maximum Angle Convex Cone (SMACC) endmember model was also used to unmix the images; however, the larger number of endmembers did not resolve the use of multiple endmembers to model the unmixed land covers and the accuracy was similar to that using SMA. The relationship between the pervious fraction estimated using the vegetation endmember and the ground reference data was stronger than that for the impervious fraction, although the fraction was underestimated. The problems in modelling highly variable impervious surfaces with a limited number of endmembers suggest that in urban environments with substantial vegetation, modelling the vegetation component as the inverse of the impervious fraction may lead to improved results. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
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18. Extended-spectrum β-lactamase producing Escherichia coli in hospital wastewaters and sewage treatment plants in Queensland, Australia.
- Author
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Gündoğdu, Aycan, Jennison, Amy V., Smith, Helen V., Stratton, Helen, and Katouli, Mohammad
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SPECTRUM analysis , *BETA lactamases , *ESCHERICHIA coli , *HOSPITAL waste disposal , *SEWAGE disposal plants - Abstract
We investigated the prevalence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in untreated hospital wastewaters and 2 sewage treatment plants (STPs). A collection of 252 ESBL-producing E. coli isolates from hospital wastewater and STPs were typed and tested for resistance to 17 antimicrobial agents and for the presence of integron-associated integrases ( intI gene) and ESBL genes. Eighty-nine percent ( n = 176) of the ESBL-producing E. coli strains from hospital wastewater were found in more than 1 sample (common types), with 1 common type accounting for 35% of isolates, found in all samples. These strains were also resistant to up to 9 non-β-lactam antibiotics and showed the same pattern of resistance in all samples. More than 73% of the hospital wastewater isolates possessed SHV-type ESBL as opposed to isolates from STPs that carried only CTX-M-type ESBL genes. The prevalence of the intI gene did not differ between the sources of the isolates. Certain ESBL-producing E. coli were dominant in hospital wastewaters. These strains possessed β-lactamase genes that were different from isolates found in STPs. From a public health point of view, the presence of such a high level of ESBL-producing E. coli strains in hospital wastewaters is of great importance. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
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19. THE VELOCITY CENTROID PERIODICITY OF L2 PUPPIS' SiO MASER EMISSION.
- Author
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MCINTOSH, GORDON C. and INDERMUEHLE, BALTHASAR
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CENTROID , *PERIODICITY in meteorology , *LARGE astronomical telescopes , *ASYMPTOTIC giant branch stars , *SPECTRUM analysis - Abstract
We report the first short term velocity centroid (VC) periodicity derived from SiO maser emission. L2 Puppis, a semi-regular AGB star, was observed using the Mopra radio telescope of the Australia Telescope National Facility in the SiO v = 1, J = 1-0 and v = 1, J = 2-1 transitions. It exhibits a 139 day period in its SiO maser VC based on a period folding analysis and a Lomb Scargle analysis. L2 Pup's SiO maser emission has an unusually large velocity range and an unusual three-peaked spectrum. To create the change in VC the entire spectrum does not shift in velocity, but changes in the relative emission of the peaks generate the variation. The changes in the VC may be due to differential illumination, an asymmetric circumstellar distribution of material, or a mixture of causes. The unusual velocity structure, similar to that observed in Orion source 1, may be due to revolution of the circumstellar material or asymmetries in the circumstellar environment. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
20. Positive backdrop for Australian bond investing
- Published
- 2011
21. Multi-frequency observations of SNR J0453-6829 in the LMC. A composite supernova remnant with a pulsar wind nebula.
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Haberl, F., Filipović, M. D., Bozzetto, L. M., Crawford, E. J., Points, S. D., Pietsch, W., De Horta, A. Y., Tothill, N., Payne, J. L., and Sasaki, M.
- Subjects
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NEBULAE , *SUPERNOVA remnants , *X-ray diffraction , *SPECTRUM analysis , *MAGELLANIC clouds ,PULSAR detection - Abstract
Context. The Large Magellanic Cloud (LMC) is rich in supernova remnants (SNRs), which can be investigated in detail with radio, optical, and X-ray observations. SNR-J0453-6829 is an X-ray and radio-bright remnant in the LMC, within which previous studies revealed the presence of a pulsar wind nebula (PWN), making it one of the most interesting SNRs in the Local Group of galaxies. Aims. We study the emission of SNR-J0453-6829 to improve our understanding of its morphology, spectrum, and thus the emission mechanisms in the shell and the PWN of the remnant. Methods. We obtained new radio data with the Australia Telescope Compact Array and analysed archival XMM-Newton observations of SNR-J0453-6829. We studied the morphology of SNR-J0453-6829 from radio, optical, and X-ray images and investigated the energy spectra in the different parts of the remnant. Results. Our radio results confirm that this LMC SNR hosts a typical PWN. The prominent central core of the PWN exhibits a radio spectral index αCore of −0.04 ± 0.04, while in the rest of the SNR shell the spectral slope is somewhat steeper with αShell = −0.43- ± -0.01. We detect regions with a mean polarisation of P ≅ (12 ± 4)% at 6 cm and (9 ± 2)% at 3 cm. The full remnant is of roughly circular shape with dimensions of (31 ± 1) pc- × (29 ± 1) pc. The spectral analysis of the XMM-Newton EPIC and RGS spectra allowed us to derive physical parameters for the SNR. Somewhat depending on the spectral model, we obtain for the remnant a shock temperature of around 0.2 keV and estimate the dynamical age to 12-000-15-000 years. Using a Sedov model we further derive an electron density in the X-ray emitting material of 1.56-cm-3, typical for LMC remnants, a large swept-up mass of 830 M⊙, and an explosion energy of 7.6 × 1050 erg. These parameters indicate a well evolved SNR with an X-ray spectrum dominated by emission from the swept-up material. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
22. Multi-frequency observations of SNRJ0453-6829 in the LMC A composite supernova remnant with a pulsar wind nebula.
- Author
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Haberl, F., Filipović, M.D., Bozzetto, L.M., Crawford, E.J., Points, S. D., Pietsch, W., De Horta, A.Y., Tothill, N., Payne, J. L., and Sasaki, M.
- Subjects
NEBULAE ,X-rays ,TELESCOPES ,SPECTRUM analysis - Abstract
Context. The Large Magellanic Cloud (LMC) is rich in supernova remnants (SNRs), which can be investigated in detail with radio, optical, and X-ray observations. SNRJ0453-6829 is an X-ray and radio-bright remnant in the LMC, within which previous studies revealed the presence of a pulsar wind nebula (PWN), making it one of the most interesting SNRs in the Local Group of galaxies. Aims. We study the emission of SNRJ0453-6829 to improve our understanding of its morphology, spectrum, and thus the emission mechanisms in the shell and the PWN of the remnant. Methods. We obtained new radio data with the Australia Telescope Compact Array and analysed archival XMM-Newton observations of SNRJ0453-6829. We studied the morphology of SNRJ0453-6829 from radio, optical, and X-ray images and investigated the energy spectra in the different parts of the remnant. Results. Our radio results confirm that this LMC SNR hosts a typical PWN. The prominent central core of the PWN exhibits a radio spectral index α
Core of -0.04 ± 0.04, while in the rest of the SNR shell the spectral slope is somewhat steeper with αShell = -0.43 ± 0.01. We detect regions with a mean polarisation of P (12 ± 4)% at 6 cm and (9 ± 2)% at 3 cm. The full remnant is of roughly circular shape with dimensions of (31±1) pc × (29±1) pc. The spectral analysis of the XMM-Newton EPIC and RGS spectra allowed us to derive physical parameters for the SNR. Somewhat depending on the spectral model, we obtain for the remnant a shock temperature of around 0.2 keV and estimate the dynamical age to 12 000-15 000 years. Using a Sedov model we further derive an electron density in the X-ray emitting material of 1.56 cm-3 , typical for LMC remnants, a large swept-up mass of 830 M☉ , and an explosion energy of 7.6 × 1050 erg. These parameters indicate a well evolved SNR with an X-ray spectrum dominated by emission from the swept-up material. [ABSTRACT FROM AUTHOR]- Published
- 2012
- Full Text
- View/download PDF
23. Long-term variations of surface and intermediate waters in the southern Indian Ocean along 32°S.
- Author
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Kobayashi, Taiyo, Mizuno, Keisuke, and Suga, Toshio
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WATER masses ,CLIMATE change ,TIME series analysis ,SALINITY ,SPECTRUM analysis - Abstract
Variations of water properties in surface and intermediate layers along 32°S in the southern Indian Ocean were examined using a 50-year (1960-2010) time series reproduced from historical hydrographic and Argo data by using optimum interpolation. Salinity in the 26.7-27.3σ density layer decreased significantly over the whole section, at a maximum rate of 0.02 decade at 26.8-26.9σ, for the 50-year average. Three deoxygenating cores were identified east of 75°E, and the increasing rate of apparent oxygen utilization in the most prominent core (26.9-27.0σ) exceeded 0.05 ml l decade. The pycnostad core of Subantarctic Mode Water (SAMW) and the salinity minimum of Antarctic Intermediate Water shifted slightly toward the lighter layers. Comparisons with trans-Indian Ocean survey data from 1936 suggest that the tendencies found in the time series began before 1960. Interestingly, cores of many prominent trends were located just offshore of Australia at 26.7-27.0σ, which is in the SAMW density range. Spectrum analysis revealed that two oscillation components with time scales of about 40 and 10 years were dominant in the subsurface layers. Our results are fairly consistent with, and thus support, the oceanic responses in the southern Indian Ocean to anthropogenic climate change predicted by model studies. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
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24. Spectral imaging of the Central Molecular Zone in multiple 3-mm molecular lines.
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Jones, P. A., Burton, M. G., Cunningham, M. R., Requena-Torres, M. A., Menten, K. M., Schilke, P., Belloche, A., Leurini, S., Martín-Pintado, J., Ott, J., and Walsh, A. J.
- Subjects
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RADIO telescopes , *IMAGING systems in astronomy , *BANDWIDTHS , *SPECTRUM analysis , *DIGITAL filters (Mathematics) , *GALACTIC center - Abstract
ABSTRACT We have mapped 20 spectral lines in the Central Molecular Zone (CMZ) around the Galactic Centre, emitting from 85.3 to 93.3 GHz. This work used the 22-m Mopra radio telescope in Australia, equipped with the 8-GHz bandwidth University of New South Wales-Mopra Spectrometer (UNSW-MOPS) digital filter bank, obtaining ∼2 km s−1 spectral and ∼40 arcsec spatial resolution. The lines measured include emission from the c-C3H2, CH3CCH, HOCO+, SO, H13CN, H13CO+, SO, H13NC, C2H, HNCO, HCN, HCO+, HNC, HC3N, 13CS and N2H+ molecules. The area covered is Galactic longitude −07 to 18 and latitude −03 to 02, including the bright dust cores around Sgr A, Sgr B2, Sgr C and G1.6−0.025. We present images from this study and conduct a principal component analysis on the integrated emission from the brightest eight lines. This is dominated by the first component, showing that the large-scale distribution of all molecules is very similar. We examine the line ratios and optical depths in selected apertures around the bright dust cores, as well as for the complete mapped region of the CMZ. We highlight the behaviour of the bright HCN, HNC and HCO+ line emission, together with that from the 13C isotopologues of these species, and compare the behaviour with that found in extragalactic sources where the emission is unresolved spatially. We also find that the isotopologue line ratios (e.g. HCO+/H13CO+) rise significantly with increasing redshifted velocity in some locations. Line luminosities are also calculated and compared to that of CO, as well as to line luminosities determined for external galaxies. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
25. Antibacterial spectrum and cytotoxic activities of serrulatane compounds from the Australian medicinal plant Eremophila neglecta.
- Author
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Anakok, O.F., Ndi, C.P., Barton, M.D., Griesser, H.J., and Semple, S.J.
- Subjects
- *
EREMOPHILA (Plants) , *SPECTRUM analysis , *CELL-mediated cytotoxicity , *GRAM-negative bacteria , *MICROBIOLOGICAL assay , *DITERPENES - Abstract
Aims: To determine the antibacterial spectrum and cytotoxic activities of serrulatane compounds from the Australian plant Eremophila neglecta. Methods and Results: Antimicrobial activities of serrulatane compounds 8,19-dihydroxyserrulat-14-ene ( 1) and 8-hydroxyserrulat-14-en-19-oic acid ( 2) were tested against Gram-negative and Gram-positive bacteria including human and veterinary pathogens and some multidrug-resistant isolates. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of the compounds were determined by broth microdilution assay. Both compounds exhibited antibacterial activity against all Gram-positive test strains. They showed antimycobacterial activity against isolates of Mycobacterium fortuitum and Mycobacterium chelonae. Of the five Gram-negative bacteria tested, only Moraxella catarrhalis showed susceptibility to the compounds. Cytotoxic activities were tested in the Vero cell line. Compound 1 showed more activity than 2 in both antibacterial and cytotoxicity assays with cytotoxicity at concentrations similar to the MBC. Conclusions: Serrulatane compounds showed significant activity against medically important bacteria, with 1 exhibiting stronger antibacterial activity. However, they also displayed toxicity to mammalian cells. Significance and Impact of the Study: Serrulatanes are of interest as novel antibacterial compounds for use in biomedical applications; this study reports data obtained with a range of bacterial strains and mammalian cells, essential for assessing the capabilities and limitations of potential applicability of these compounds. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
26. Instability of Antibacterial Serrulatane Compounds from the Australian Plant Species Eremophila duttonii.
- Author
-
Ndi, Chi P., Semple, Susan J., and Griesser, Hans J.
- Subjects
- *
ANTIBACTERIAL agents , *PLANT species , *DITERPENES , *SPECTRUM analysis , *HYDROXYL group - Abstract
Hydrophilically substituted diterpenes of the structural class of serrulatanes have attracted attention as novel antibacterial compounds that are effective even against multidrug-resistant Staphylococcus aureus, a key bacterium involved in human infections. The mechanism of action has, however, not been established yet. Available data on structure-activity relationships suggest that the aromatic hydroxy group is essential for activity, and the strongest activity has been found for naphthyl compounds. In this context, it is reported that two highly active serrulatanes isolated from leaf resin of the Australian plant species Eremophila duttonii showed instability upon separation. Acetylation of hydroxy groups generated stable compounds that could be isolated and identified by NMR spectroscopy. The acetylated compounds showed little antibacterial activity, but such activity, as well as oxidative instability, was restored after hydrolysis of the acetate groups. Thus, phenolic hydroxy groups are essential for the mechanism of action of these compounds. The reaction products were not purifiable in sufficient quantities, but indications point to oxidation to quinones. Such oxidation may be a key aspect of the antibacterial activity of this class of compounds. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
27. Airborne geophysical mapping of the Australian continent.
- Author
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Minty, Brian R. S.
- Subjects
GAMMA rays ,SPECTROMETRY ,SPECTRUM analysis ,EXPLORERS - Abstract
Many countries have significant coverage of publicly funded airborne magnetic and gamma-ray spectrometric surveys that are available to explorers as precompetitive information to encourage exploration. However, individual surveys are generally small, and after decades of data acquisition, explorers are faced with the problem of how to effectively combine the individual surveys into coherent regional compilations. The Australian government's response was to fly a baseline survey over the whole of Australia at approximately 75-km flight line spacing. This has enabled all of Australia's public-domain magnetic and gamma-ray spectrometric surveys to be leveled to common datums using new techniques facilitated by the baseline control provided by the new traverses. This adds significant value to these data, as they can now be used for the interpretation of regional-scale features and for direct comparison of geophysical signatures from different parts of the continent. Also, quantitative modeling and analysis of the data can now be carried out over much larger areas. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
28. The First Chemists an Australian Chronicle Part 7
- Author
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Collins, David J
- Published
- 2010
29. Heronapyrroles A−C: Farnesylated 2-Nitropyrroles from an Australian Marine-Derived Streptomycessp.
- Author
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Ritesh Raju, Andrew M. Piggott, Leticia X. Barrientos Diaz, Zeinab Khalil, and Robert. J. Capon
- Subjects
- *
PYRROLES , *ANALYTICAL chemistry , *TERPENES , *MOLECULAR structure , *STREPTOMYCES , *MARINE bacteria , *SPECTRUM analysis , *GRAM-positive bacteria , *CELL lines - Abstract
Chemical analysis of a marine-derived Streptomycessp. (CMB-M0423) isolated from beach sand off Heron Island, Australia, yielded three new members of the rare pyrroloterpene biosynthetic structure class. Identified by detailed spectroscopic analysis as the first reported examples of naturally occurring 2-nitropyrroles, heronapyrroles A−C (1−3) displayed promising biological activitywith low to submicromolar IC50activity against Gram-positive bacteria but no cytotoxicity toward mammalian cell lines. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
30. Characterising spectral sea wave conditions with statistical clustering of actual spectra
- Author
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Hamilton, L.J.
- Subjects
- *
OCEAN waves , *SPECTRUM analysis , *OCEAN engineering , *OCEANOGRAPHY , *SEA breeze - Abstract
Abstract: The Clustering LARge Applications (CLARA) statistical sampling and clustering algorithm is used to classify sea wave spectra into groups with different spectral properties. The actual spectrum is used in the classification, not proxy sets of spectral parameters. The clustering needs no a priori information on spectral properties, statistical distributions, or number of modes in the spectra. Cluster membership can be viewed as being essentially determined by the geometrical or shape properties of spectra, and is uninfluenced by the numerical dominance of particular shapes if a sufficient number of clusters is requested. The CLARA algorithm also enables outlier detection. CLARA provides a spectrum from each grouping or cluster as a central tendency measure or medoid. This allows a collection of spectra to be reduced to a set of basis or representative spectra according to the different spectral shapes present. However, other statistical measures constructed from the clusters form more suitable basis spectra than medoids. The methods are illustrated with a one-year long waverider data set from a shallow water coastal site off northwest Australia. The site experiences spectral peaks in three frequency bands, seasonally changing conditions, and daily sea breezes. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
31. 9-(5'-Deoxy-5'-thio-β-D-xylofuranosyl)adenine Disulfide from the Southern Australian Marine Sponge Trachycladus laevispirulifer: the First Natural Occurrence of a Nucleoside Disulfide.
- Author
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Chongsheng Peng, G. M. Kamal B. Gunaherath, Andrew M. Piggott, Zeinab Khalil, Melissa Conte, and Robert J. Capon
- Subjects
- *
ADENINE , *SPONGES (Invertebrates) , *NUCLEOSIDES , *SULFIDES , *MOLECULAR structure , *ANTIBACTERIAL agents , *SPECTRUM analysis - Abstract
Chemical fractionation of a southern Australian marine sponge, Trachycladus laevispirulifer, yielded 9-(5â²-deoxy-5â²-thio-β-d-xylofuranosyl)adenine disulfide as the first recorded natural occurrence of a nucleoside disulfide, and only the second of a xylo-nucleoside. Structure elucidation of the disulfide was achieved by detailed spectroscopic analysis and comparison to synthetic model compounds. The antibacterial, antifungal, and anticancer properties of the disulfide are documented and the literature surrounding natural and synthetic thionucleosides is reviewed. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
32. Determination of fecal contamination indicator sterols in an Australian water supply system.
- Author
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Hussain, Malik A., Ford, Rebecca, and Hill, Julian
- Subjects
RECONNAISSANCE operations ,WATER pollution ,SPECTRUM analysis ,STEROLS ,SEWAGE ,WATER supply ,FECAL contamination ,BACTERIAL pollution of water - Abstract
This paper reports a reconnaissance survey of the concentrations of sterol compounds (as indicators of fecal contamination) in a large water supply system in southeast Australia comprising a network of rivers, channels, and drains. Levels of coprostanol and cholestanol were determined in surface water and bottom sediment using gas chromatography–mass spectrometry analysis across 17 strategic sampling sites and over 12 months. Clear differences in the levels of fecal contamination were observed among sites. Four sites routinely contained high levels of the fecal indicator sterols indicated from surface water and sediment sample analysis. Coprostanol concentrations at each location varied from 0 ng/L at the reference site to 11,327 ng/L in a surface water sample of a drain directly downstream of a knackery. The majority of the sites contained coprostanol in the range of 500 to 800 ng/L. Since no fecal-associated sterol compounds were detected at the external reference sites, these were assumed to be free from fecal contamination. Sewage water discharge and/or substantial water runoff maybe the principal factors contributing to fecal contamination of the supply drains and channels. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
33. A silhouette envelope around GGD30IR detected by Spitzer.
- Author
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Smith, R. G. and Wright, C. M.
- Subjects
- *
GALAXIES , *ASTRONOMICAL observations , *SPECTRUM analysis , *TELESCOPES - Abstract
This paper presents a study of the envelope of the young stellar object (YSO) GGD30IR. What distinguishes this from most other YSOs is the elongated absorption feature seen in silhouette against the background emission in the Spitzer Galactic Legacy Infrared Midplane Survey Extraordinaire 8 μm Infrared Array Camera image of the region. The size and the symmetrical placement of GGD30IR in the centre of this feature suggest that it is an extended envelope, perhaps the remnant of the collapse of the GGD30 core. We have used the extinction in the envelope measured from (i) the reduction in the 8 μm background intensity and (ii) field star colour excesses, to estimate the envelope mass, obtaining values of 0.6 ± 0.2 and , respectively. To investigate the envelope further, we have obtained Australia Telescope Compact Array 3 mm continuum and HCO+ line observations of the region. The continuum emission at 3 mm arises from both a compact (unresolved; ≤730 au) core embedded in an extended envelope ∼18 000 au × 38 000 au in extent. We estimate the core mass to be 0.11 ± 0.02 . The HCO+ emission is extended in a direction perpendicular to the long axis of the envelope, suggesting it comes from an outflow. The spectral energy distribution (SED) provides a 2–24 μm spectral index, α= 1.0, which places GGD30IR in the Class I YSO category. Integrating the SED provides a luminosity of . [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
34. Study of the Periodicities of Lightning Activity in Three Main Thunderstorm Centers Based on Schumann Resonance Measurements.
- Author
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Nieckarz, Zenon, Zięba, Stanisław, Kułak, Andrzej, and Michalec, Adam
- Subjects
- *
LIGHTNING , *RESONANCE , *SPECTRUM analysis , *FACILITIES - Abstract
Time variations of lightning activity in the three main tropical thunderstorm centers located in the Maritime Continent (Pakistan, India, Southeast Asia, Indonesia, and Australia), Africa, and the Americas are analyzed using a lightning activity index IRS, which is calculated from the resonances of magnetic field in the extremely low frequency range—the Schumann resonances—which were observed at Hylaty station (Poland) in the time interval July 2005–May 2006. Power spectrum analysis of the IRS series is carried out for this time interval. The annual and semiannual variations are shown in all of the series together with the following characteristic periodicities: 45 (Madden–Julian oscillation), 17.6, 13.5, and 4.8 days, seen mainly in the series describing the lightning activity of the Maritime Continent. In addition, maps of the dynamical power spectrum are constructed. They present variability both in the values of characteristic periods 26–30, 17–22, 12–14, 9–10, and 5–7 days and in their duration. During the studied time interval, according to these indices, the African center was the most active, whereas the American and Maritime Continent centers showed a similar level of activity. The largest differences among the centers were observed in the summer months in the Northern Hemisphere. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
35. e-VLBI observations of GHz-peaked spectrum radio sources in nearby galaxies from the AT20G survey.
- Author
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Hancock, Paul J., Tingay, Steven J., Sadler, Elaine M., Phillips, Chris, and Deller, Adam T.
- Subjects
- *
VERY long baseline interferometry , *SPECTRUM analysis , *GALAXY clusters , *SURVEYS , *RADIO galaxies - Abstract
Gigahertz-peaked spectrum (GPS) radio sources are thought to be young objects which later evolve into Fanaro–Riley type I (FR I) and FR II radio galaxies. We have used the Australia Telescope 20 GHz (AT20G) survey catalogue to select a uniform sample of GPS sources with spectral peaks above 5 GHz, which should represent the youngest members of this class. In this paper, we present e-VLBI observations of 10 such objects which are associated with nearby galaxies and so represent a new population of local, low-power GPS sources. Our e-VLBI observations were carried out at 4.8 GHz with the Australia Telescope Long Baseline Array (LBA) using a real-time software correlator. All 10 sources were detected, and were unresolved on scales of ∼100 mas, implying that they are typically less than 100 pc in linear size. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
36. Search for main-line OH emission toward high-latitude IRAS sources in the southern hemisphere.
- Author
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Lyubchenko, S. Yu., Alakoz, A. V., Val'tts, I. E., and Slysh, V. I.
- Subjects
- *
MASERS , *ELECTROMAGNETISM , *SPECTRUM analysis , *QUANTUM electronics - Abstract
We present the results of a search for the emission in the main OH lines toward high-latitude IRAS sources using the Australia Telescope Compact Array (ATCA) in Narrabri. A sample of 239 sources from the IRAS catalog selected with the color criterion for ultracompact HII regions and with no restriction on flux was studied. No maser or thermal emission or absorption was detected in these sources. The reason for this could be the low sensitivity of the ATCA to faint high-latitude objects. However, we have mapped the regions of eight known masers in star-forming regions in the plane of the Galaxy. The results are given in the form of spectra and maps. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
37. A generalizable method for remote sensing of canopy nitrogen across a wide range of forest ecosystems
- Author
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Martin, M.E., Plourde, L.C., Ollinger, S.V., Smith, M.-L., and McNeil, B.E.
- Subjects
- *
FOREST canopy ecology , *REMOTE sensing , *FOLIAR diagnosis , *NITROGEN cycle , *SPECTRUM analysis - Abstract
Abstract: A growing number of investigations have shown that remote sensing of foliar nitrogen (N) concentration in plant canopies can be achieved with imaging spectroscopy, or hyperspectral remote sensing, from satellite or airborne sensors. Development of this approach has been fueled by recognition that foliar N is related to a variety of ecological and biogeochemical processes, ranging from the spread of invasive species to the ecosystem effects of insect defoliation events to patterns of N cycling in forest soils. To date, most studies have focused on building site-specific foliar N detection algorithms applied to individual scenes or small landscapes that have been intensively characterized with local field measurements. However, the growing number of well-measured sites, combined with improvements in image data quality and processing methods provide an opportunity to begin seeking more general N detection methods that can be applied to a broader range of sites or to locations that lack intensive field measurements. Here, we combine data from several independent efforts in North America, Central America and Australia, to examine whether development of calibration methods to determine canopy nitrogen concentration across a wide range of forest ecosystems is possible. The analysis included data from 137 individual field plots within eight study sites for which imagery has been acquired from NASA''s Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and/or Hyperion instruments. The combined dataset was used to evaluate site-specific calibration results as well as results obtained with data pooled across all sites. We evaluated the accuracy of results using plot- and site-level cross-validation wherein individual plots or entire sites were withheld and used as an independent validation of the resulting algorithms. In instances where all sites were represented in the calibration, canopy-level foliar N concentration was predicted to within 7–15% of the mean field-measured values indicating a strong potential for broadly applied foliar N detection. When whole sites were iteratively dropped from the calibration and predicted by remaining data, predictions were still significant, but less accurate (7–47% of mean canopy-level N concentration). This suggests that further development to include a wider range of ecosystems will be necessary before cross-site prediction accuracy approaches that seen in site-specific calibrations. Nevertheless, we view these results as promising, particularly given the potential value of foliar N estimates, even at a reduced level of confidence, at sites for which there is no possibility of conducting field data collections. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
38. OPTICAL SPECTRA OF RADIO PLANETARY NEBULAE IN THE LARGE MAGELLANIC CLOUD.
- Author
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Payne, J. L., Filipović, M. D., Millar, W. C., Crawford, E. J., De Horta, A. Y., Stootman, F. H., and Urošević, D.
- Subjects
- *
SPECTRUM analysis , *PLANETARY nebulae , *INTERSTELLAR medium , *MAGELLANIC clouds - Abstract
We present 11 spectra from 12 candidate radio sources co-identified with known planetary nebulae (PNe) in the Large Magellanic Cloud (LMC). Originally found in Australia Telescope Compact Array (ATCA) LMC surveys at 1.4, 4.8 and 8.64 GHz and confirmed by new high resolution ATCA images at 6 and 3 cm (400/200), these complement data recently presented for candidate radio PNe in the Small Magellanic Cloud (SMC). Their spectra were obtained using the Radclifie 1.9-meter telescope in Sutherland (South Africa). All of the optical PNe and radio candidates are within 200 and may represent a population of selected radio bright sample only. Nebular ionized masses of these objects are estimated to be as high as 1.8 Mʘ, supporting the idea that massive PNe progenitor central stars lose much of their mass in the asymptotic giant branch (AGB) phase or prior. We also identify a sub-political. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
39. Soil organic carbon prediction by hyperspectral remote sensing and field vis-NIR spectroscopy: An Australian case study
- Author
-
Gomez, Cécile, Viscarra Rossel, Raphael A., and McBratney, Alex B.
- Subjects
- *
SOIL testing , *SPECTRUM analysis , *REMOTE sensing - Abstract
Abstract: This paper compares predictions of soil organic carbon (SOC) using visible and near infrared reflectance (vis–NIR) hyperspectral proximal and remote sensing data. Soil samples were collected in the Narrabri region, dominated by Vertisols, in north western New South Wales (NSW), Australia. Vis–NIR spectra were collected over this region proximally with an AgriSpec portable spectrometer (350–2500 nm) and remotely from the Hyperion hyperspectral sensor onboard satellite (400–2500 nm). SOC contents were predicted by partial least-squares regression (PLSR) using both the proximal and remote sensing spectra. The spectral resolution of the proximal and remote sensing data did not affect prediction accuracy. However, predictions of SOC using the Hyperion spectra were less accurate than those of the Agrispec data resampled to similar resolution as the Hyperion spectra. Finally, the SOC map predicted using Hyperion data shows similarity with field observations. There is potential for the use of hyperspectral remote sensing for predictions of soil organic carbon. The use of these techniques will facilitate the implementation of digital soil mapping. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
40. The extragalactic radio-source population at 95 GHz.
- Author
-
Sadler, Elaine M., Ricci, Roberto, Ekers, Ronald D., Sault, Robert J., Jackson, Carole A., and De Zotti, Gianfranco
- Subjects
- *
RADIO sources (Astronomy) , *SPECTRUM analysis , *REDSHIFT , *COSMIC background radiation , *SURVEYS - Abstract
We have used the Australia Telescope Compact Array (ATCA) at 95 GHz to carry out continuum observations of 130 extragalactic radio sources selected from the Australia Telescope 20 GHz (AT20G) survey. We use a triple-correlation method to measure simultaneous 20- and 95-GHz flux densities for these objects, and over 90 per cent of our target sources are detected at 95 GHz. We demonstrate that the ATCA can robustly measure 95-GHz flux densities with an accuracy of ∼10 per cent in a few minutes for sources stronger than about 50 mJy. We measure the distribution of radio spectral indices in a flux-limited sample of extragalactic sources, and show that the median 20–95 GHz spectral index does not vary significantly with flux density for . This finding allows us to estimate the extragalactic radio source counts at 95 GHz by combining our observed 20–95 GHz spectral-index distribution with the accurate 20-GHz source counts measured in the AT20G survey. Our derived 95-GHz source counts at flux densities above 80 mJy are significantly lower than those found by several previous studies. The main reason is that most radio sources with flat or rising spectra in the frequency range 5–20 GHz show a spectral turnover between 20 and 95 GHz. As a result, there are fewer 95-GHz sources (by almost a factor of 2 at 0.1 Jy) than would be predicted on the basis of extrapolation from the source populations seen in lower-frequency surveys. We also derive the predicted confusion noise in cosmic microwave background surveys at 95 GHz and find a value 20–30 per cent lower than previous estimates. The 95-GHz source population at the flux levels probed by this study is dominated by quasi-stellar objects with a median redshift . We find a correlation between optical magnitude and 95-GHz flux density which suggests that many of the brightest 95-GHz sources may be relativistically beamed, with both the optical and millimetre continuum significantly brightened by Doppler boosting. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
41. Using strain birefringence in diamond to estimate the remnant pressure on an inclusion.
- Author
-
Barron, L.M., Mernagh, T.P., and Barron, B.J.
- Subjects
- *
DIAMONDS , *GARNET , *NATIVE element minerals , *MINERALS , *DOUBLE refraction , *RAMAN spectroscopy , *SPECTRUM analysis - Abstract
Raman spectroscopy is used to identify minerals in isolated sealed inclusion chambers in some New South Wales (Australia) diamonds and to determine the remnant internal pressure on each inclusion with values of each: 3.03, 3.31 and 3.54 - 3.62 GPa for coesite, 0.42, 1.36 and 2.3 GPa for diopsidic omphacite, and 0.8 GPa for grossular garnet, each determination for a different uncut stone. The diamond stress due to remnant pressure was found to be proportional to the maximum strain birefringence around each inclusion, as measured by the Berek compensator, with the constant (K = 1000 / 5.8, R2 = 0.93) independent of the inclusion mineral, size, orientation and shape within the limits of error. Thus, simple birefringence measurements of diamond adjacent to inclusions can be used to estimate remnant pressures on inclusions. The calibration shows that one of the stressed diamonds has an anomalously low strain birefringence. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
42. The Australia Telescope 20-GHz (AT20G) Survey: the Bright Source Sample.
- Author
-
Massardi, Marcella, Ekers, Ronald D., Murphy, Tara, Ricci, Roberto, Sadler, Elaine M., Burke, Sarah, De Zotti, Gianfranco, Edwards, Philip G., Hancock, Paul J., Jackson, Carole A., Kesteven, Michael J., Mahony, Elizabeth, Phillips, Christopher J., Staveley-Smith, Lister, Subrahmanyan, Ravi, Walker, Mark A., and Wilson, Warwick E.
- Subjects
- *
ASTRONOMICAL observations , *SPECTRUM analysis , *RADIO sources (Astronomy) , *REDSHIFT - Abstract
The Australia Telescope 20-GHz (AT20G) Survey is a blind survey of the whole southern sky at 20 GHz (with follow-up observations at 4.8 and 8.6 GHz) carried out with the Australia Telescope Compact Array from 2004 to 2007. The Bright Source Sample (BSS) is a complete flux-limited subsample of the AT20G Survey catalogue comprising 320 extragalactic ) radio sources south of with Jy. Of these, 218 have near simultaneous observations at 8 and 5 GHz. In this paper we present an analysis of radio spectral properties in total intensity and polarization, size, optical identifications and redshift distribution of the BSS sources. The analysis of the spectral behaviour shows spectral curvature in most sources with spectral steepening that increases at higher frequencies (the median spectral index α, assuming , decreases from between 4.8 and 8.6 GHz to between 8.6 and 20 GHz), even if the sample is dominated by flat spectra sources (85 per cent of the sample has . The almost simultaneous spectra in total intensity and polarization allowed us a comparison of the polarized and total intensity spectra: polarized fraction slightly increases with frequency, but the shapes of the spectra have little correlation. Optical identifications provided an estimation of redshift for 186 sources with a median value of 1.20 and 0.13, respectively, for QSO and galaxies. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
43. Equatorial wave analysis from SABER and ECMWF temperatures.
- Author
-
Ern, M., Preusse, P., Krebsbach, M., Mlynczak, M. G., and Russell III, J. M.
- Subjects
WAVE analysis ,GRAVITY waves ,HYDRODYNAMICS ,STRATOSPHERE ,SPECTRUM analysis ,TROPOSPHERE ,ATMOSPHERE - Abstract
Equatorial planetary scale wave modes such as Kelvin waves or Rossby-gravity waves are excited by convective processes in the troposphere. In this paper an analysis for these and other equatorial wave modes is carried out with special focus on the stratosphere using temperature data from the SABER satellite instrument as well as ECMWF temperatures. Space-time spectra of symmetric and antisymmetric spectral power are derived to separate the different equatorial wave types and the contribution of gravity waves is determined from the spectral background of the space-time spectra. Both gravity waves and equatorial planetary scale wave modes are main drivers of the quasi-biennial oscillation (QBO) in the stratosphere. Temperature variances attributed to the different wave types are calculated for the period from February 2002 until March 2006 and compared to previous findings. A comparison between SABER and ECMWF wave analyses shows that in the lower stratosphere SABER and ECMWF spectra and temperature variances agree remarkably well while in the upper stratosphere ECMWF tends to overestimate Kelvin wave components. Gravity wave variances are partly reproduced by ECMWF but have a significant low-bias. For the examples of a QBO westerly phase (October-December 2004) and a QBO easterly phase (November/December 2005, period of the SCOUT-O3 tropical aircraft campaign in Darwin/Australia) in the lower stratosphere we find qualitatively good agreement between SABER and ECMWF in the longitude-time distribution of Kelvin, Rossby (n=1), and Rossby-gravity waves. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
44. Second-Order Theory and Setup in Surface Gravity Waves: A Comparison with Experimental Data.
- Author
-
Toffoli, A., Onorato, M., Babanin, A. V., Bitner-Gregersen, E., Osborne, A. R., and Monbaliu, J.
- Subjects
- *
NUMERICAL analysis , *LAKES , *SPECTRUM analysis , *HYDRODYNAMICS , *QUALITATIVE chemical analysis - Abstract
The second-order, three-dimensional, finite-depth wave theory is here used to investigate the statistical properties of the surface elevation and wave crests of field data from Lake George, Australia. A direct comparison of experimental and numerical data shows that, as long as the nonlinearity is small, the second-order model describes the statistical properties of field data very accurately. By low-pass filtering the Lake George time series, there is evidence that some energetic wave groups are accompanied by a setup instead of a setdown. A numerical study of the coupling coefficient of the second-order model reveals that such an experimental result is consistent with the second-order theory, provided directional spreading is included in the wave spectrum. In particular, the coupling coefficient of the second-order difference contribution predicts a setup as a result of the interaction of two waves with the same frequency but with different directions. This result is also confirmed by numerical simulations. Bispectral analysis, furthermore, indicates that this setup is a statistically significant feature of the observed wave records. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
45. Geotechnical properties of cemented paste backfill from Cannington Mine, Australia.
- Author
-
Rudd Rankine and Nagaratnam Sivakugan
- Subjects
PASTE ,MINERAL industries ,SPECTRUM analysis - Abstract
Abstract  Paste fill is the newest form of backfill material in the spectrum available to international mines and is made from full mill tailings. Tailings have an effective grain size of approximately 5 μm and are combined with a small portion of binder and water to make paste. It is deposited into the voids created by mining which are referred to as stopes. The empty voids are approximated as vertical rectangular prisms, with plan dimensions of 15â40 m and heights of 100 m or more. Backfilling of mined stopes provide an increased level of local and regional stability to the ore body, as well as providing a suitable and economic dump of mining related waste. Paste is a relatively new technology in the mining industry and a review of the physical properties and mechanical fill behaviour was considered pertinent. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
46. Discrimination of blackberry (Rubus fruticosus sp. agg.) using hyperspectral imagery in Kosciuszko National Park,NSW, Australia
- Author
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Dehaan, Remy, Louis, John, Wilson, Andrea, Hall, Andrew, and Rumbachs, Rod
- Subjects
- *
PLANT protection laws , *BLACKBERRIES , *SPECTRUM analysis - Abstract
Abstract: Blackberry, Rubus fruticosus sp. agg., is a perennial, semi-deciduous shrub which forms dense thickets that infest approximately 8.8 million ha of land in Australia. It is highly invasive with a high potential for spread, and causes significant negative economic and environmental impacts. During 2004, HyMap hyperspectral imagery was acquired across the foreshores of Blowering Dam in Kosciuszko National Park, NSW, Australia to evaluate its utility for mapping the distribution of blackberry. Strategies for mapping image-derived blackberry spectra using hyperspectral imagery were assessed using Spectral Angle Mapper, Spectral Feature Fitting, Matched Filter, and Mixture-Tuned Matched Filter mapping algorithms. A Mixture-Tuned Matched Filter (MTMF) approach using the blackberry spectrum with a restricted wavelength range was adopted. MTMF distribution maps showed the highest agreement to the distribution of blackberry as assessed using an error matrix and independent groundtruth data. The MTMF distribution map generated a producer''s accuracy of 91%, user''s accuracy of 81%, overall accuracy of 92% and a Kappa coefficient of 0.715. This study has demonstrated that hyperspectral imagery can effectively quantify the distribution of blackberry in open canopies. [Copyright &y& Elsevier]
- Published
- 2007
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47. Effect of Overlying Windrowed Harvest Residues on Soil Carbon and Nitrogen in Hoop Pine Plantations of Subtropical Australia.
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Blumfield, Timothy J., Zhihong Xu, Prasolova, Nina V., and Mathers, Nicole J.
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ARAUCARIA cunninghamii ,TROPICAL plants ,BIODEGRADATION ,PLANTATIONS ,NITROGEN ,ANAEROBIC bacteria ,NUCLEAR magnetic resonance ,SPECTRUM analysis - Abstract
Background, Aims and Scope. Harvest residues were formed into windrows to prevent nitrogen (N) losses through volatilisation and erosion that occurred following pile and burn operations in hoop pine (Araucaria cunninghamii Aiton ex A. Cunn.) plantations of subtropical Australia. We selected second rotation (2R) hoop pine sites where the windrows (10–15 m apart) had been formed 1, 2 and 3 years prior to sampling in order to examine soil carbon (C) and N in the areas beneath and between the windrows. Methods. We used conventional chemical methods, anaerobic incubation assay,
13 C and15 N natural abundance analyses and, solid-state13 C nuclear magnetic resonance (NMR) spectroscopy. Results. Percent mineralisable N (PCMN) was the only parameter in the underneath windrow position at the Year 1 site that did not show a significant difference to the rest of the positions along the transect. However positions adjacent to windrows did have significantly greater PCMN at the Year 1 site than other positions along the transect. PCMN, total N and total C were significantly greater underneath the windrows at the Year 3 site, whilst δ13 C was significantly more negative in the underneath windrow positions. Discussion. PCMN was the most sensitive biological indicator of the changes occurring in the soil due to decomposition of the windrows, with the beneath-windrow position having a significantly higher PCMN than the inter-windrow position (p<.0.001) at the Year 3 site. Isotopic natural abundance for both13 C and was able to detect the influx of labile materials from new residues. Solid-state13 C NMR was able to detect inputs of labile C from the windrows at the Year 1 site, whilst the increase in aromatic C at the Year 3 site was indicative of the more advanced stages of windrow decomposition. Conclusions. Decomposition of windrowed residues had a beneficial effect on soil N and C pools. However, the effect remained localised after 3 years, indicating that trees needed to be planted close to the windrows to gain any benefit from residue decomposition. Recommendations and Perspectives. The use of windrows allows a clear planting area and provides a good barrier against soil erosion. However, trees can only gain access to the nutrients from the decomposing residues if they are planted close to the windrows. Limiting the width of the cleared areas to allow for only 2 planting rows will give the maximum benefit to the developing trees. [ABSTRACT FROM AUTHOR]- Published
- 2006
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48. 1.4-GHz polarimetric observations of the two fields imaged by the DASI experiment.
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Bernardi, G., Carretti, E., Sault, R. J., Cortiglioni, S., and Poppi, S.
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SPECTRUM analysis , *EMISSION spectroscopy , *COSMIC background radiation , *TELESCOPES , *SYNCHROTRONS - Abstract
We present results of polarization observations at 1.4 GHz of the two fields imaged by the DASI experiment ( and , respectively). Data were taken with the Australia Telescope Compact Array with 3.4-arcmin resolution and ∼0.18-mJy beam−1 sensitivity. The emission is dominated by point sources, and we do not find evidence for diffuse synchrotron radiation even after source subtraction. This allows to estimate an upper limit of the diffuse polarized emission. The extrapolation to 30 GHz suggests that the synchrotron radiation is lower than the polarized signal measured by the DASI experiment by at least two orders of magnitude. This further supports the conclusions drawn by the DASI team itself about the negligible Galactic foreground contamination in their data set, improving by a factor of ∼5 the upper limit estimated by Leitch et al. The dominant point-source emission allows us to estimate the contamination of the cosmic microwave background (CMB) by extragalactic foregrounds. We computed the power spectrum of their contribution, and its extrapolation to 30 GHz provides a framework where the CMB signal should dominate. However, our results do not match the conclusions of the DASI team about the negligibility of point-source contamination, suggesting taking into account a source subtraction from the DASI data. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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49. Combining mass spectrometry based electronic nose, visible–near infrared spectroscopy and chemometrics to assess the sensory properties of Australian Riesling wines
- Author
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Cozzolino, Daniel, Smyth, Heather E., Lattey, Kate A., Cynkar, Wies, Janik, Les, Dambergs, Robert G., Francis, I. Leigh, and Gishen, Mark
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RIESLING , *INFRARED spectroscopy , *SPECTRUM analysis - Abstract
Abstract: The combination of mass spectrometry (MS) based electronic nose (eNose) with visible (VIS) and near infrared spectroscopy (NIR) was explored as an objective tool to measure sensory attributes in commercial Riesling wines grown in Australia. Calibration models were developed between instrumental data and sensory scores using partial least squares (PLS) regression with full cross validation. Good correlations (r >0.70, root mean square standard error in cross validation (RMSECV): 0.66) were found for developed and floral; intermediate (0.70> r >0.60, RMSECV: 0.84 and 0.63) for tropical and low (r<0.50, RMSECV: 0.98) for green characters measured by a sensory panel and the combination of both techniques. The results suggested that data from instrumental techniques coupled with chemometrics might be related with sensory scores measured by a trained panel. The study is considered a starting point in order to evaluate useful sources of information generated by different instrumental techniques with the objective to select combination of sensors for specific wine quality attributes. [Copyright &y& Elsevier]
- Published
- 2006
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50. Integration of Optical and Radar Classifications for Mapping Pasture Type in Western Australia.
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Michael J. Hill, Catherine J. Ticehurst, Jong-sen Lee, Mitchell R. Grunes, Graham E. Donald, and David Henry
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SYNTHETIC aperture radar , *OPTICS , *IMAGING systems , *COHERENT radar , *SPECTRUM analysis - Abstract
In this study, independent classifications of Landsat Thematic Mapper imagery and Jet Propulsion Laboratory AirSAR were combined to create an integrated classification of pasture and other vegetation types for a study area in the agricultural zone of Western Australia. The resulting classification combines greenness and brightness information from optical data with structure and water content information from synthetic aperture radar (SAR). Field observations of vegetation type, botanical composition, ground cover percentage, wet and dry biomass, canopy height, and soil water content were collected at 34 sites representing a range of pastures, browse shrubs, and crops. An unsupervised version of the Complex Wishart classification procedure, based on preserving scattering characteristics from the Freeman and Durden backscatter decomposition, was applied to the C-, L-, and P-band polarimetric SAR data. The optical classification was carried out using a principle component analysis on the green, red, and near-infrared bands and clustering on the basis of a class centroid distance measure and knowledge of ground targets. These two classification results were then fused together. Assessment of a confusion matrix using the individual sites showed that identification of more uniform, dense, and structurally distinct canopies was better than that of more diverse, sparse, and structurally ambiguous canopies, as the former were better represented by the canopy height attribute used in the SAR classification component. The optical classification enabled correction of SAR misclassification of vegetation due to surface roughness and soil moisture effects, or similar backscatter responses from herbaceous or arboreal canopies. The results show that simplification of vegetation into groups based upon properties with sensitive responses in both the optical and SAR domains, and combination of separate SAR and optical classifications, has potential for improving classification of diverse and heterogeneous herbaceous and browse cover in grazing lands. However, collection of ground calibration data must be at an appropriate spatial scale and include canopy and surface measurements directly related to backscatter mechanisms and spectral sensitivity. [ABSTRACT FROM AUTHOR]
- Published
- 2005
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