TY  - JOUR
AU  - Blesić, Suzana
AU  - du Preez, D. Jean
AU  - Stratimirović, Đorđe
AU  - Ajtić, Jelena
AU  - Ramotsehoa, M. Cynthia
AU  - Allen, Martin W.
AU  - Wright, Caradee Y.
PY  - 2020
UR  - https://smile.stomf.bg.ac.rs/handle/123456789/2485
AB  - Studies of personal solar ultraviolet radiation (pUVR) exposure are important to identify populations at-risk of excess and insufficient exposure given the negative and positive health impacts, respectively, of time spent in the sun. Electronic UVR dosimeters measure personal solar UVR exposure at high frequency intervals generating large datasets. Sophisticated methods are needed to analyze these data. Previously, wavelet transform (WT) analysis was applied to high-frequency personal recordings collected by electronic UVR dosimeters. Those findings showed scaling behavior in the datasets that changed from uncorrelated to long-range correlated with increasing duration of time spent in the sun. We hypothesized that the WT slope would be influenced by the duration of time that a person spends in continuum outside. In this study, we address this hypothesis by using an experimental study approach. We aimed to corroborate this hypothesis and to characterize the extent and nature of influence time a person spends outside has on the shape of statistical functions that we used to analyze individual UVR exposure patterns. Detrended fluctuation analysis (DFA) was applied to personal sun exposure data. We analyzed sun exposure recordings from skiers (on snow) and hikers in Europe, golfers in New Zealand and outdoor workers in South Africa. Results confirmed validity of the DFA superposition rule for assessment of pUVR data and showed that pUVR scaling is determined by personal patterns of exposure on lower scales. We also showed that this dominance ends at the range of time scales comparable to the maximal duration of continuous exposure to solar UVR during the day; in this way the superposition rule can be used to quantify behavioral patterns, particularly accurate if it is determined on WT curves. These findings confirm a novel way in which large datasets of personal UVR data may be analyzed to inform messaging regarding safe sun exposure for human health.
PB  - Academic Press Inc Elsevier Science, San Diego
T2  - Environmental Research
T1  - Characterization of personal solar ultraviolet radiation exposure using detrended fluctuation analysis
VL  - 182
DO  - 10.1016/j.envres.2019.108976
ER  - 

@article{
author = "Blesić, Suzana and du Preez, D. Jean and Stratimirović, Đorđe and Ajtić, Jelena and Ramotsehoa, M. Cynthia and Allen, Martin W. and Wright, Caradee Y.",
year = "2020",
abstract = "Studies of personal solar ultraviolet radiation (pUVR) exposure are important to identify populations at-risk of excess and insufficient exposure given the negative and positive health impacts, respectively, of time spent in the sun. Electronic UVR dosimeters measure personal solar UVR exposure at high frequency intervals generating large datasets. Sophisticated methods are needed to analyze these data. Previously, wavelet transform (WT) analysis was applied to high-frequency personal recordings collected by electronic UVR dosimeters. Those findings showed scaling behavior in the datasets that changed from uncorrelated to long-range correlated with increasing duration of time spent in the sun. We hypothesized that the WT slope would be influenced by the duration of time that a person spends in continuum outside. In this study, we address this hypothesis by using an experimental study approach. We aimed to corroborate this hypothesis and to characterize the extent and nature of influence time a person spends outside has on the shape of statistical functions that we used to analyze individual UVR exposure patterns. Detrended fluctuation analysis (DFA) was applied to personal sun exposure data. We analyzed sun exposure recordings from skiers (on snow) and hikers in Europe, golfers in New Zealand and outdoor workers in South Africa. Results confirmed validity of the DFA superposition rule for assessment of pUVR data and showed that pUVR scaling is determined by personal patterns of exposure on lower scales. We also showed that this dominance ends at the range of time scales comparable to the maximal duration of continuous exposure to solar UVR during the day; in this way the superposition rule can be used to quantify behavioral patterns, particularly accurate if it is determined on WT curves. These findings confirm a novel way in which large datasets of personal UVR data may be analyzed to inform messaging regarding safe sun exposure for human health.",
publisher = "Academic Press Inc Elsevier Science, San Diego",
journal = "Environmental Research",
title = "Characterization of personal solar ultraviolet radiation exposure using detrended fluctuation analysis",
volume = "182",
doi = "10.1016/j.envres.2019.108976"
}

Blesić, S., du Preez, D. J., Stratimirović, Đ., Ajtić, J., Ramotsehoa, M. C., Allen, M. W.,& Wright, C. Y.. (2020). Characterization of personal solar ultraviolet radiation exposure using detrended fluctuation analysis. in Environmental Research
Academic Press Inc Elsevier Science, San Diego., 182.
https://doi.org/10.1016/j.envres.2019.108976

Blesić S, du Preez DJ, Stratimirović Đ, Ajtić J, Ramotsehoa MC, Allen MW, Wright CY. Characterization of personal solar ultraviolet radiation exposure using detrended fluctuation analysis. in Environmental Research. 2020;182.
doi:10.1016/j.envres.2019.108976 .

Blesić, Suzana, du Preez, D. Jean, Stratimirović, Đorđe, Ajtić, Jelena, Ramotsehoa, M. Cynthia, Allen, Martin W., Wright, Caradee Y., "Characterization of personal solar ultraviolet radiation exposure using detrended fluctuation analysis" in Environmental Research, 182 (2020),
https://doi.org/10.1016/j.envres.2019.108976 . .

TY  - JOUR
AU  - Sarvan, Darko
AU  - Stratimirović, Đorđe
AU  - Blesić, Suzana
AU  - Đurđević, Vladimir
AU  - Miljković, Vladimir
AU  - Ajtić, Jelena
PY  - 2017
UR  - https://smile.stomf.bg.ac.rs/handle/123456789/2198
AB  - The dynamics of the beryllium-7 specific activity in surface air over 1987-2011 is analyzed using wavelet transform (WT) analysis and time -dependent detrended moving average (tdDMA) method, WT analysis gives four periodicities in the beryllium-7 specific activity: one month, three months, one year, and three years. These intervals are further used in tdDMA to calculate local autocorrelation exponents for precipitation, tropopause height and teleconnection indices. Our results show that these parameters share common periods with the beryllium-7 surface concentration. tdDMA method indicates that on the characteristic intervals of one year and shorter, the beryllium-7 specific activity is strongly autocorrelated. On the three-year interval, the beryllium-7 specific activity shows periods of anticorrelat ion, implying slow changes in its dynamics that become evident only over a prolonged period of time. A comparison of the Hurst exponents of all the variables on the one- and three-year intervals suggest some similarities in their dynamics. Overall, a good agreement in the behavior of the teleconnection indices and specific activity of beryllium-7 in surface air is noted.
PB  - Elsevier, Amsterdam
T2  - Physica A-Statistical Mechanics & its Applications
T1  - Dynamics of beryllium-7 specific activity in relation to meteorological variables, tropopause height, teleconnection indices and sunspot number
VL  - 469
SP  - 813
EP  - 823
DO  - 10.1016/j.physa.2016.11.040
ER  - 

@article{
author = "Sarvan, Darko and Stratimirović, Đorđe and Blesić, Suzana and Đurđević, Vladimir and Miljković, Vladimir and Ajtić, Jelena",
year = "2017",
abstract = "The dynamics of the beryllium-7 specific activity in surface air over 1987-2011 is analyzed using wavelet transform (WT) analysis and time -dependent detrended moving average (tdDMA) method, WT analysis gives four periodicities in the beryllium-7 specific activity: one month, three months, one year, and three years. These intervals are further used in tdDMA to calculate local autocorrelation exponents for precipitation, tropopause height and teleconnection indices. Our results show that these parameters share common periods with the beryllium-7 surface concentration. tdDMA method indicates that on the characteristic intervals of one year and shorter, the beryllium-7 specific activity is strongly autocorrelated. On the three-year interval, the beryllium-7 specific activity shows periods of anticorrelat ion, implying slow changes in its dynamics that become evident only over a prolonged period of time. A comparison of the Hurst exponents of all the variables on the one- and three-year intervals suggest some similarities in their dynamics. Overall, a good agreement in the behavior of the teleconnection indices and specific activity of beryllium-7 in surface air is noted.",
publisher = "Elsevier, Amsterdam",
journal = "Physica A-Statistical Mechanics & its Applications",
title = "Dynamics of beryllium-7 specific activity in relation to meteorological variables, tropopause height, teleconnection indices and sunspot number",
volume = "469",
pages = "813-823",
doi = "10.1016/j.physa.2016.11.040"
}

Sarvan, D., Stratimirović, Đ., Blesić, S., Đurđević, V., Miljković, V.,& Ajtić, J.. (2017). Dynamics of beryllium-7 specific activity in relation to meteorological variables, tropopause height, teleconnection indices and sunspot number. in Physica A-Statistical Mechanics & its Applications
Elsevier, Amsterdam., 469, 813-823.
https://doi.org/10.1016/j.physa.2016.11.040

Sarvan D, Stratimirović Đ, Blesić S, Đurđević V, Miljković V, Ajtić J. Dynamics of beryllium-7 specific activity in relation to meteorological variables, tropopause height, teleconnection indices and sunspot number. in Physica A-Statistical Mechanics & its Applications. 2017;469:813-823.
doi:10.1016/j.physa.2016.11.040 .

Sarvan, Darko, Stratimirović, Đorđe, Blesić, Suzana, Đurđević, Vladimir, Miljković, Vladimir, Ajtić, Jelena, "Dynamics of beryllium-7 specific activity in relation to meteorological variables, tropopause height, teleconnection indices and sunspot number" in Physica A-Statistical Mechanics & its Applications, 469 (2017):813-823,
https://doi.org/10.1016/j.physa.2016.11.040 . .

TY  - JOUR
AU  - Blesić, Suzana
AU  - Stratimirović, Đorđe
AU  - Ajtić, Jelena
AU  - Wright, Caradee Y.
AU  - Allen, Martin W.
PY  - 2016
UR  - https://smile.stomf.bg.ac.rs/handle/123456789/2098
AB  - Personal sun exposure measurements provide important information to guide the development of sun awareness and disease prevention campaigns. We assess the scaling properties of personal ultraviolet radiation (pUVR) sun exposure measurements using the wavelet transform (WT) spectral analysis to process long-range, high-frequency personal recordings collected by electronic UVR dosimeters designed to measure erythemal UVR exposure. We analysed the sun exposure recordings of school children, farmers, marathon runners and outdoor workers in South Africa, and construction workers and work site supervisors in New Zealand. We found scaling behaviour in all the analysed pUVR data sets. We found that the observed scaling changes from uncorrelated to long-range correlated with increasing duration of sun exposure. Peaks in the WT spectra that we found suggest the existence of characteristic times in sun exposure behaviour that were to some extent universal across our data set. Our study also showed that WT measures enable group classification, as well as distinction between individual UVR exposures, otherwise unattainable by conventional statistical methods.
PB  - Nature Publishing Group, New York
T2  - Journal of Exposure Science & Environmental Epidemiology
T1  - Novel approach to analysing large data sets of personal sun exposure measurements
VL  - 26
IS  - 6
SP  - 613
EP  - 620
DO  - 10.1038/jes.2016.43
ER  - 

@article{
author = "Blesić, Suzana and Stratimirović, Đorđe and Ajtić, Jelena and Wright, Caradee Y. and Allen, Martin W.",
year = "2016",
abstract = "Personal sun exposure measurements provide important information to guide the development of sun awareness and disease prevention campaigns. We assess the scaling properties of personal ultraviolet radiation (pUVR) sun exposure measurements using the wavelet transform (WT) spectral analysis to process long-range, high-frequency personal recordings collected by electronic UVR dosimeters designed to measure erythemal UVR exposure. We analysed the sun exposure recordings of school children, farmers, marathon runners and outdoor workers in South Africa, and construction workers and work site supervisors in New Zealand. We found scaling behaviour in all the analysed pUVR data sets. We found that the observed scaling changes from uncorrelated to long-range correlated with increasing duration of sun exposure. Peaks in the WT spectra that we found suggest the existence of characteristic times in sun exposure behaviour that were to some extent universal across our data set. Our study also showed that WT measures enable group classification, as well as distinction between individual UVR exposures, otherwise unattainable by conventional statistical methods.",
publisher = "Nature Publishing Group, New York",
journal = "Journal of Exposure Science & Environmental Epidemiology",
title = "Novel approach to analysing large data sets of personal sun exposure measurements",
volume = "26",
number = "6",
pages = "613-620",
doi = "10.1038/jes.2016.43"
}

Blesić, S., Stratimirović, Đ., Ajtić, J., Wright, C. Y.,& Allen, M. W.. (2016). Novel approach to analysing large data sets of personal sun exposure measurements. in Journal of Exposure Science & Environmental Epidemiology
Nature Publishing Group, New York., 26(6), 613-620.
https://doi.org/10.1038/jes.2016.43

Blesić S, Stratimirović Đ, Ajtić J, Wright CY, Allen MW. Novel approach to analysing large data sets of personal sun exposure measurements. in Journal of Exposure Science & Environmental Epidemiology. 2016;26(6):613-620.
doi:10.1038/jes.2016.43 .

Blesić, Suzana, Stratimirović, Đorđe, Ajtić, Jelena, Wright, Caradee Y., Allen, Martin W., "Novel approach to analysing large data sets of personal sun exposure measurements" in Journal of Exposure Science & Environmental Epidemiology, 26, no. 6 (2016):613-620,
https://doi.org/10.1038/jes.2016.43 . .

TY  - CONF
AU  - Stratimirović, Đorđe
AU  - Blesić, Suzana
AU  - Wright, Caradee Y.
AU  - Allen, Martin W.
AU  - Ajtić, Jelena
PY  - 2015
UR  - https://smile.stomf.bg.ac.rs/handle/123456789/2057
AB  - Scaling properties of personal solar ultraviolet radiation exposure (pUVR) recordings are investigated using the Wavelet Transform (WT) spectral analysis. Personal UVR recordings are collected by UVR monitors designed to measure erythemal UVR. Sun exposure recordings of a school child, farmer, marathon runner and outdoor worker in South Africa are analyzed. A scaling behavior in all analyzed pUVR datasets is found. The scaling behavior changes from uncorrelated to long-range correlated as duration of a person's solar exposure increases. The slopes of calculated WT power vary from 0, in the uncorrelated case for persons with erratic activities in reference to their UVR exposure, to close to 1 in the case of long-range correlated pUVR data, for persons spending longer periods in the sun. Peaks in the WT power spectra are also found, pointing to the existence of characteristic times in sun exposure behavior. Characteristic peaks at approximately 15 minutes, half an hour and an hour are present in all pUVR data, while persons with longer sun exposure have additional peaks at longer periods.
PB  - RAD Association
C3  - RAD Conference Proceedings
T1  - Wavelet analysis of personal solar UVR exposure
VL  - 2015-June
SP  - 443
EP  - 446
UR  - https://hdl.handle.net/21.15107/rcub_veterinar_1253
ER  - 

@conference{
author = "Stratimirović, Đorđe and Blesić, Suzana and Wright, Caradee Y. and Allen, Martin W. and Ajtić, Jelena",
year = "2015",
abstract = "Scaling properties of personal solar ultraviolet radiation exposure (pUVR) recordings are investigated using the Wavelet Transform (WT) spectral analysis. Personal UVR recordings are collected by UVR monitors designed to measure erythemal UVR. Sun exposure recordings of a school child, farmer, marathon runner and outdoor worker in South Africa are analyzed. A scaling behavior in all analyzed pUVR datasets is found. The scaling behavior changes from uncorrelated to long-range correlated as duration of a person's solar exposure increases. The slopes of calculated WT power vary from 0, in the uncorrelated case for persons with erratic activities in reference to their UVR exposure, to close to 1 in the case of long-range correlated pUVR data, for persons spending longer periods in the sun. Peaks in the WT power spectra are also found, pointing to the existence of characteristic times in sun exposure behavior. Characteristic peaks at approximately 15 minutes, half an hour and an hour are present in all pUVR data, while persons with longer sun exposure have additional peaks at longer periods.",
publisher = "RAD Association",
journal = "RAD Conference Proceedings",
title = "Wavelet analysis of personal solar UVR exposure",
volume = "2015-June",
pages = "443-446",
url = "https://hdl.handle.net/21.15107/rcub_veterinar_1253"
}

Stratimirović, Đ., Blesić, S., Wright, C. Y., Allen, M. W.,& Ajtić, J.. (2015). Wavelet analysis of personal solar UVR exposure. in RAD Conference Proceedings
RAD Association., 2015-June, 443-446.
https://hdl.handle.net/21.15107/rcub_veterinar_1253

Stratimirović Đ, Blesić S, Wright CY, Allen MW, Ajtić J. Wavelet analysis of personal solar UVR exposure. in RAD Conference Proceedings. 2015;2015-June:443-446.
https://hdl.handle.net/21.15107/rcub_veterinar_1253 .

Stratimirović, Đorđe, Blesić, Suzana, Wright, Caradee Y., Allen, Martin W., Ajtić, Jelena, "Wavelet analysis of personal solar UVR exposure" in RAD Conference Proceedings, 2015-June (2015):443-446,
https://hdl.handle.net/21.15107/rcub_veterinar_1253 .

TY  - CONF
AU  - Ajtić, Jelena
AU  - Maletić, Dimitrije
AU  - Stratimirović, Đorđe
AU  - Blesić, Suzana
AU  - Nikolić, Jelena
AU  - Đurđević, Vladimir
AU  - Todorović, Dragana
PY  - 2015
UR  - https://smile.stomf.bg.ac.rs/handle/123456789/2056
AB  - Dependence of the lead-210 activity concentration in surface air on meteorological variables and teleconnection indices is investigated using multivariate analysis, which gives the Boosted Decision Trees method as the most suitable for variable analysis. A mapped functional behaviour of the lead-210 activity concentration is further obtained, and used to test predictability of lead-210 in surface air. The results show an agreement between the predicted and measured values. The temporal evolution of the measured activities is satisfactorily matched by the prediction. The largest qualitative differences are obtained for winter months.
PB  - RAD Association
C3  - RAD Conference Proceedings
T1  - Predictability of lead-210 in surface air based on multivariate analysis
VL  - 2015-June
SP  - 317
EP  - 322
UR  - https://hdl.handle.net/21.15107/rcub_vinar_7129
ER  - 

@conference{
author = "Ajtić, Jelena and Maletić, Dimitrije and Stratimirović, Đorđe and Blesić, Suzana and Nikolić, Jelena and Đurđević, Vladimir and Todorović, Dragana",
year = "2015",
abstract = "Dependence of the lead-210 activity concentration in surface air on meteorological variables and teleconnection indices is investigated using multivariate analysis, which gives the Boosted Decision Trees method as the most suitable for variable analysis. A mapped functional behaviour of the lead-210 activity concentration is further obtained, and used to test predictability of lead-210 in surface air. The results show an agreement between the predicted and measured values. The temporal evolution of the measured activities is satisfactorily matched by the prediction. The largest qualitative differences are obtained for winter months.",
publisher = "RAD Association",
journal = "RAD Conference Proceedings",
title = "Predictability of lead-210 in surface air based on multivariate analysis",
volume = "2015-June",
pages = "317-322",
url = "https://hdl.handle.net/21.15107/rcub_vinar_7129"
}

Ajtić, J., Maletić, D., Stratimirović, Đ., Blesić, S., Nikolić, J., Đurđević, V.,& Todorović, D.. (2015). Predictability of lead-210 in surface air based on multivariate analysis. in RAD Conference Proceedings
RAD Association., 2015-June, 317-322.
https://hdl.handle.net/21.15107/rcub_vinar_7129

Ajtić J, Maletić D, Stratimirović Đ, Blesić S, Nikolić J, Đurđević V, Todorović D. Predictability of lead-210 in surface air based on multivariate analysis. in RAD Conference Proceedings. 2015;2015-June:317-322.
https://hdl.handle.net/21.15107/rcub_vinar_7129 .

Ajtić, Jelena, Maletić, Dimitrije, Stratimirović, Đorđe, Blesić, Suzana, Nikolić, Jelena, Đurđević, Vladimir, Todorović, Dragana, "Predictability of lead-210 in surface air based on multivariate analysis" in RAD Conference Proceedings, 2015-June (2015):317-322,
https://hdl.handle.net/21.15107/rcub_vinar_7129 .

TY  - CONF
AU  - Ajtić, Jelena
AU  - Stratimirović, Đorđe
AU  - Đurđević, Vladimir
AU  - Todorović, D.
AU  - Nikolić, J.
PY  - 2014
UR  - https://smile.stomf.bg.ac.rs/handle/123456789/1934
AB  - Activities of beryllium-7 and lead-210 are monitored in ground level air in Belgrade, Serbia. The measuring sites are located at the Institute of Nuclear Sciences Vinča. The activities are determined on HPGe detectors by standard gamma spectrometry. Five teleconnection indices of large scale atmospheric circulation: North Atlantic Oscillation, East Atlantic Pattern, East Atlantic/West Russia Pattern, Scandinavia Pattern, and Polar/Eurasia Pattern are obtained from the data archive of the United States National Oceanic and Atmospheric Administration's Climate Prediction Center. The collected time series consist of monthly values and span more than two decades: beryllium-7 since 1991, lead-210 since 1985, and the teleconnection indices since 1950, thus offering data arrays of sufficient lengths for wavelet spectral analysis. A relation between the radionuclides' activities and the indices is first investigated using Pearson's correlation coefficients. The computed coefficients do not indicate a linear relationship between the variables. However, the wavelet spectral analysis shows a number of common characteristic frequencies in the data arrays. The annual cycle of all the variables is clearly evident. A common time period of two to three years is also found, as well as a higher frequency variability corresponding to five to six months.
PB  - RAD Association
C3  - RAD Conference Proceedings
T1  - Wavelet spectral analysis of teleconnection indices and activities of beryllium-7 and lead-210 in ground level air in Belgrade, Serbia
VL  - 2014-May
SP  - 53
EP  - 56
UR  - https://hdl.handle.net/21.15107/rcub_veterinar_1130
ER  - 

@conference{
author = "Ajtić, Jelena and Stratimirović, Đorđe and Đurđević, Vladimir and Todorović, D. and Nikolić, J.",
year = "2014",
abstract = "Activities of beryllium-7 and lead-210 are monitored in ground level air in Belgrade, Serbia. The measuring sites are located at the Institute of Nuclear Sciences Vinča. The activities are determined on HPGe detectors by standard gamma spectrometry. Five teleconnection indices of large scale atmospheric circulation: North Atlantic Oscillation, East Atlantic Pattern, East Atlantic/West Russia Pattern, Scandinavia Pattern, and Polar/Eurasia Pattern are obtained from the data archive of the United States National Oceanic and Atmospheric Administration's Climate Prediction Center. The collected time series consist of monthly values and span more than two decades: beryllium-7 since 1991, lead-210 since 1985, and the teleconnection indices since 1950, thus offering data arrays of sufficient lengths for wavelet spectral analysis. A relation between the radionuclides' activities and the indices is first investigated using Pearson's correlation coefficients. The computed coefficients do not indicate a linear relationship between the variables. However, the wavelet spectral analysis shows a number of common characteristic frequencies in the data arrays. The annual cycle of all the variables is clearly evident. A common time period of two to three years is also found, as well as a higher frequency variability corresponding to five to six months.",
publisher = "RAD Association",
journal = "RAD Conference Proceedings",
title = "Wavelet spectral analysis of teleconnection indices and activities of beryllium-7 and lead-210 in ground level air in Belgrade, Serbia",
volume = "2014-May",
pages = "53-56",
url = "https://hdl.handle.net/21.15107/rcub_veterinar_1130"
}

Ajtić, J., Stratimirović, Đ., Đurđević, V., Todorović, D.,& Nikolić, J.. (2014). Wavelet spectral analysis of teleconnection indices and activities of beryllium-7 and lead-210 in ground level air in Belgrade, Serbia. in RAD Conference Proceedings
RAD Association., 2014-May, 53-56.
https://hdl.handle.net/21.15107/rcub_veterinar_1130

Ajtić J, Stratimirović Đ, Đurđević V, Todorović D, Nikolić J. Wavelet spectral analysis of teleconnection indices and activities of beryllium-7 and lead-210 in ground level air in Belgrade, Serbia. in RAD Conference Proceedings. 2014;2014-May:53-56.
https://hdl.handle.net/21.15107/rcub_veterinar_1130 .

Ajtić, Jelena, Stratimirović, Đorđe, Đurđević, Vladimir, Todorović, D., Nikolić, J., "Wavelet spectral analysis of teleconnection indices and activities of beryllium-7 and lead-210 in ground level air in Belgrade, Serbia" in RAD Conference Proceedings, 2014-May (2014):53-56,
https://hdl.handle.net/21.15107/rcub_veterinar_1130 .