Radiocarbon Dating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buchholz, B A

Radiocarbon dating can be used to determine the age of objects that contain components that were once alive. In the case of human remains, a radiocarbon date can distinguish between a crime scene and an archeological site. Documents, museum artifacts and art objects can be dated to determine if their age is correct for the historical context. A radiocarbon date does not confirm authenticity, but it can help identify a forgery.

Some connectivity indices and zagreb index of polyhex nanotubes.

PubMed

Farahani, Mohammad Reza

2012-12-01

Several topological indices are investigated in polyhex nanotubes: Randić connectivity index, sum-connectivity index, atom-bond connectivity index, geometric-arithmetic index, First and Second Zagreb indices and Zagreb polynomials. Formulas for calculating the above topological descriptors in polyhex zigzag TUZC6[m,n] and armchair TUAC6[m,n] nanotube families are given.

Radiocarbon dating in archaeology: Interdisciplinary aspects and consequences (an overview)

NASA Astrophysics Data System (ADS)

Palincaş, Nona

2017-06-01

This paper is an overview of recent developments in the radiocarbon dating of the most frequently analyzed archaeological materials - wood, short-lived plants, and human and animal bones - and draws attention to two sets of consequences. Firstly, while radiocarbon dating has become more accessible to archaeologists thanks to an increase in the number of laboratories, a lowering of prices, and a reduction in sample sizes, it has also grown far more dependent on fields of research, other than the traditional chemical pretreatment of samples and the physics involved in their measurement, such as wood anatomy and other fields of botany, stable isotope-based diet studies, geochemistry, micromorphology, statistics, etc., most of which are not easily accessible by the vast majority of users of radiocarbon dating (and sometimes not familiar to practicing archaeologists). Secondly, given that, on the one hand, there is still much scope for research in radiocarbon dating and, on the other, archaeological sites are a limited resource, there is need to create archives containing the detailed documentation of samples and, whenever possible, sample residues.

The profile of scabies patients in Zagreb.

PubMed

Kosanović Ličina, Mirjana Lana; Quiaios, André; Tešić, Vanja; Domingues, José; Sá, Nelson

2014-12-01

Scabies is a mandatory notifiable disease according to Croatian law. Due to an increased reports of scabies within a couple of years in Zagreb, we decided to present epidemiological characteristics of patients diagnosed with scabies in Zagreb. A retrospective survey was carried out in county Public Health Institute "Dr. Andrija Stampar" in Zagreb and analysis was performed for the period of 2010-2013 upon individual notifications on scabies cases. The patients are presented by sociodemographic data, diagnosis and treatment. In a 4 year period there were 246 scabies cases recorded in Zagreb. Cases have been registered in all quarters of the City. The highest incidence (50/100 000) was recorded in every child age group following by incidence of over 30/100 000 in elderly institutionalized in nursing homes. In almost two thirds of patients management of scabies has not been conducted in accordance to current guidelines. 10% of scabies cases were found in medical health personnel predominantly in those working in nursing homes and psychiatric wards. A small amount of cases 19 (8%) were infected outside Croatia; the majority of these cases 15 (78%) are registered within last two years. High percentage of scabies cases registered in nursing homes and psychiatric wards suggests that there is a need of raising awareness on scabies epidemiology and management by public health officers. Due to a higher incidence of scabies in children age, the obligation of medical practitioners is also to emphasize the importance of following treatment guidelines. In order to control scabies cases as well to prevent outbreaks within hospital wards or nursing homes there is an obligation of implementation of strict guidelines regarding treatment of scabies and a public health service referral.

The role of inter-comparisons in radiocarbon quality assurance

NASA Astrophysics Data System (ADS)

Scott, Marian; Cook, Gordon; Naysmith, Philip

2016-04-01

Radiocarbon dating is used widely in many geochronology projects as a basis for the creation and testing of chronological constructs. Radiocarbon measurements are by their nature complex and the degree of sample pre-treatment varies considerably depending on the material. Within the UK and Europe, there are a number of well-established laboratories and increasingly, scientists are not just commissioning new dates, but also using statistical modelling of assemblages of dates, perhaps measured in different laboratories, to provide formal date estimates for their investigations. The issue of comparability of measurements (and thus bias, accuracy and precision of measurement) from the diverse laboratories is one which has been the focus of some attention both within the 14C community and the wider user communities for some time. As a result of this but also as part of laboratory benchmarking and quality assurance, the 14C community has undertaken a wide-scale, far-reaching and evolving programme of inter-comparisons, to the benefit of laboratories and users alike. This paper presents the results from the most recent exercise SIRI. The objectives of SIRI included, through choice of material, to contribute to the discussion concerning laboratory offsets and error multipliers in the context of IntCal (the International Calibration Programme) and to gain a better understanding of differences in background derived from a range of infinite age material types.

Entrepreneurialism at the University of Zagreb: Managing the Sustainability of Change

ERIC Educational Resources Information Center

Vidovic, Vlasta Vizek; Bjelis, Aleksa

2006-01-01

This article presents a study of the different aspects of entrepreneurialism at the University of Zagreb in the context of Croatian higher education. The recent history of changes at the University of Zagreb is described using a temporal perspective from the beginning of the development of the European Higher Education Area to the implementation…

Comparison of Psychotropic Drug Prescribing Quality between Zagreb, Croatia and Sarajevo, B&H.

PubMed

Polić-Vižintin, Marina; Štimac, Danijela; Čatić, Tarik; Šostar, Zvonimir; Zelić, Ana; Živković, Krešimir; Draganić, Pero

2014-12-01

The purpose of this paper was to compare outpatient consumption and quality of psychotropic drug prescribing between Croatia and Bosnia & Herzegovina 2006-2010. Data on drug utilization from Zagreb Municipal Pharmacy and Sarajevo Public Pharmacy were used to calculate the number of defined daily doses (DDD) and DDD per 1000 inhabitants per day (DDD/TID) using the WHO Anatomical-Therapeutic-Chemical methodology. Total utilization of psychopharmaceuticals increased in both cities; however, it was higher in Zagreb than in Sarajevo throughout the study period. The utilization of psycholeptics increased in Zagreb by 2.4% (from 74.5 to 76.3 DDD/TID) and in Sarajevo by 3.8% (from 62.4 to 64.8 DDD/TID). The utilization of anxiolytics decreased in Zagreb by 2.1% and in Sarajevo by even 18.7%. The utilization of antidepressants increased in both cities with predominance of SSRI over TCA utilization, greater in Sarajevo (96.6%) than in Zagreb (10.2%). The anxiolytic/antidepressant ratio decreased by 11.1% in Zagreb (from 2.87 to 2.55) and by 58.7% in Sarajevo (from 5.66 to 2.34). Outpatient utilization of antipsychotics increased significantly in Sarajevo, predominated by typical ones, whereas in Zagreb the utilization of antipsychotics was stable, predominated by atypical ones. In Croatia and Bosnia & Herzegovina, there was an obvious tendency to follow western trends in drug prescribing, as demonstrated by the increased use of antidepressants and reduced use of anxiolytics. Despite some improvement observed in the prescribing quality, high use of antipsychotics with dominance of typical antipsychotics in Sarajevo points to the need of prescribing guidelines for antipsychotics.

Influence of aeroallergens on the incidence of conjunctivitis in Zagreb and Zagreb County.

PubMed

Peternel, Renata; Toth, Ivan; Hercog, Predrag; Vojniković, Bozo; Cop, Rasa; Bradić-Hammoud, Mirna

2013-04-01

The aim of this study was to determine the temporal and spatial variations of pollen spectra in the City of Zagreb and Zagreb County according to frequency of inhalation allergy and rhino-conjunctivitis in the adult population by setting allergen/patient relationship. The study was carried out at three inland sites in Croatia during four years (2003-2006). A number of 2,192 patients have been tested for allergy skin prick tests over the same period. The majority of patients allergic to pollen allergens were sensitized to allergens from the plant pollen which belong to the botanical family of grass 46.91%, ambrosia 42.07%, birch 25.66%, hazel 15.19% (with symptoms of rhinoconjunctivitis (42.5%), conjunctivitis (28.3%) and rhinitis (23.9%). Increased symptoms in patients allergic to pollen allergens in the entire study period coincided with the presence of pollen in the air. Patients sensitized to dust mites have symptoms throughout the year with a slightly increased number of cases in April and June. In patients sensitized to fungi and mold spores and animal hairs, the number of cases with worsening of symptoms is equal during the same year.

Low energy cyclotron for radiocarbon dating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Welch, J.J.

1984-12-01

The measurement of naturally occurring radioisotopes whose half lives are less than a few hundred million years but more than a few years provides information about the temporal behavior of geologic and climatic processes, the temporal history of meteoritic bodies as well as the production mechanisms of these radioisotopes. A new extremely sensitive technique for measuring these radioisotopes at tandem Van de Graaff and cyclotron facilities has been very successful though the high cost and limited availability have been discouraging. We have built and tested a low energy cyclotron for radiocarbon dating similar in size to a conventional mass spectrometer.more » These tests clearly show that with the addition of a conventional ion source, the low energy cyclotron can perform the extremely high sensitivity /sup 14/C measurements that are now done at accelerator facilities. We found that no significant background is present when the cyclotron is tuned to accelerate /sup 14/C negative ions and the transmission efficiency is adequate to perform radiocarbon dating on milligram samples of carbon. The internal ion source used did not produce sufficient current to detect /sup 14/C directly at modern concentrations. We show how a conventional carbon negative ion source, located outside the cyclotron magnet, would produce sufficient beam and provide for quick sampling to make radiocarbon dating milligram samples with a modest laboratory instrument feasible.« less

Outpatient utilization of psychopharmaceuticals: comparison between the cities of Zagreb and Sarajevo (2006-2009).

PubMed

Catić, Tarik; Stimac, Danijela; Zivković, Krešimir; Zelić, Ana

2012-08-01

To determine the real outpatient utilization of psychiatric drugs in Zagreb (Croatia) and Sarajevo (Bosnia and Herzegovina) and to compare the outpatient utilization of psychiatric drugs between this two cities. Data on the outpatient utilization of psycholpetics and psychoanaleptics (N05 and N06) in both cities were received from pharmacies and collected during 2006-2009. Based on the data obtained, a number of DDD and DDD per 1000 inhabitants perday (DDD/1000/day) has been calculated. The data in Zagreb were received from all pharmacies in Zagreb, whereas only 50% of pharmacies in Sarajevo participated, thus an extrapolation of data for Sarajevo was required and accomplished. All drugs were classified according to the ATC system. Based on the data obtained, a number of DDD and DDD/1000/day was calculated for all N05 and N06 drugs. Overall utilization trend was similar between the cities Sarajevo and Zagreb and followed trends in other neighbouring countries. Total consumption of psycholeptics and psychoanaleptics in Sarajevo was 22.6% (on average) lower than in Zagreb, during the 4-year period. During the 2006-2009 period the total consumption of psychopharmaceuticals showed increasing trend with peak in 2008 with similar trend between Zagreb and Sarajevo. It is necessary to implement systematic approach to drug utilization monitoring in Sarajevo and Bosnia and Herzegovina in general in order to improve prescribing quality as it is done in Croatia.

Simultaneous measurement of tritium and radiocarbon by ultra-low-background proportional counting.

PubMed

Mace, Emily; Aalseth, Craig; Alexander, Tom; Back, Henning; Day, Anthony; Hoppe, Eric; Keillor, Martin; Moran, Jim; Overman, Cory; Panisko, Mark; Seifert, Allen

2017-08-01

Use of ultra-low-background capabilities at Pacific Northwest National Laboratory provide enhanced sensitivity for measurement of low-activity sources of tritium and radiocarbon using proportional counters. Tritium levels are nearly back to pre-nuclear test backgrounds (~2-8 TU in rainwater), which can complicate their dual measurement with radiocarbon due to overlap in the beta decay spectra. We present results of single-isotope proportional counter measurements used to analyze a dual-isotope methane sample synthesized from ~120mg of H 2 O and present sensitivity results. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simultaneous measurement of tritium and radiocarbon by ultra-low-background proportional counting

DOE PAGES

Mace, Emily; Aalseth, Craig; Alexander, Tom; ...

2016-12-21

Use of ultra-low-background capabilities at Pacific Northwest National Laboratory provide enhanced sensitivity for measurement of low-activity sources of tritium and radiocarbon using proportional counters. Tritium levels are nearly back to pre-nuclear test backgrounds (~2-8 TU in rainwater), which can complicate their dual measurement with radiocarbon due to overlap in the beta decay spectra. In this paper, we present results of single-isotope proportional counter measurements used to analyze a dual-isotope methane sample synthesized from ~120 mg of H 2O and present sensitivity results.

A combined method for DNA analysis and radiocarbon dating from a single sample.

PubMed

Korlević, Petra; Talamo, Sahra; Meyer, Matthias

2018-03-07

Current protocols for ancient DNA and radiocarbon analysis of ancient bones and teeth call for multiple destructive samplings of a given specimen, thereby increasing the extent of undesirable damage to precious archaeological material. Here we present a method that makes it possible to obtain both ancient DNA sequences and radiocarbon dates from the same sample material. This is achieved by releasing DNA from the bone matrix through incubation with either EDTA or phosphate buffer prior to complete demineralization and collagen extraction utilizing the acid-base-acid-gelatinization and ultrafiltration procedure established in most radiocarbon dating laboratories. Using a set of 12 bones of different ages and preservation conditions we demonstrate that on average 89% of the DNA can be released from sample powder with minimal, or 38% without any, detectable collagen loss. We also detect no skews in radiocarbon dates compared to untreated samples. Given the different material demands for radiocarbon dating (500 mg of bone/dentine) and DNA analysis (10-100 mg), combined DNA and collagen extraction not only streamlines the sampling process but also drastically increases the amount of DNA that can be recovered from limited sample material.

Cardiovascular drugs consumption--comparison between two Croatian regions, City of Zagreb and Lika-Senj County.

PubMed

Jurković, Drazen; Stimac, Danijela; Bajramović, Dubravko; Tiljak, Hrvoje; Stevanović, Ranko

2014-06-01

The aim of this paper is to determine the differences in the outpatient consumption of cardiovascular drugs between Croatian regions: the City of Zagreb and Lika-Senj County. The data on the number of packages and the purchase price for each drug have been obtained from all pharmacies in Lika-Senj County and all pharmacies in the City of Zagreb. Defined daily doses/1000 inhabitants/day (DDD/1000/day) was calculated for every drug in accordance with its code name and Anatomical Therapeutic Chemical/Defined Daily Dose (ATC/DDD) index of the World Health Organization (WHO) for 2007. For drug combinations without defined daily doses, equivalent doses (ED) were used. The quality of drug prescribing within the group of cardiovascular drugs was assessed using the Drug Utilization (DU90%) method and the adherence of the DU90% segment to the guidelines for prescribing individual drug groups. The statistical significance of differences in results between the City of Zagreb and Lika-Senj County was tested using the chi-square test at the level of statistical significance p < 0.05. The comparison of the share of the five most often prescribed drug groups in Lika-Senj County has shown statistically significant differences when compared to the City of Zagreb (chi2 = 28.93, df = 4, p < 0.001). The total outpatient consumption of cardiovascular drugs in the City of Zagreb and Lika-Senj County differs significantly. The consumption, quality of prescribing drugs and cost/DDD in the City of Zagreb is higher than in Lika-Senj County; in the City of Zagreb, newer and more expensive drugs are prescribed to a higher extent.

Radiocarbon Dating, Memories, and Hopes

DOE R&D Accomplishments Database

Libby, W. F.

1972-10-01

The history of radiocarbon dating from 1939 to the present is reviewed. The basic principles of radiocarbon dating are that cosmic rays make living things radioactive with {sup 14}C to a certain level fixed by the environment and that at death the intake of food stops so no replenishment of the {sup 14}C steadily lost by the immutable decay occurs. Therefore measurement of the degree of decay gives the time lapse since death, i.e., the radiocarbon age. The equipment developed and experiments performed to measure the specific activity of specimens to be dated are described. The results obtained by world-wide experimenters are discussed. These showed that on simultaneity radiocarbon dating is apparently reliable but that absolute dates may be incorrect by as much as 600 to 700 y. The value of radiocarbon dating to archaeologists, geologists, climatologists, and historians is stressed. (LCL)

An overview of mosquitoes and emerging arboviral infections in the Zagreb area, Croatia.

PubMed

Klobucar, Ana; Benic, Nikola; Krajcar, Darko; Kosanovic-Licina, Mirjana Lana; Tesic, Vanja; Merdic, Enrih; Vrucina, Ivana; Savic, Vladimir; Barbic, Ljubo; Stevanovic, Vladimir; Pem-Novosel, Iva; Vilibic-Cavlek, Tatjana

2016-12-30

Mosquito control in the Zagreb area has been conducted for many years, whereas the fauna has only been investigated in the last 20 years. So far 30 mosquito species have been detected in the city area. Culex pipiens form molestus is the dominant mosquito species in indoor breeding sites. In forested areas and areas exposed to flooding, the active period is early spring and the dominant species are Ochlerotatus sticticus, Ochlerotatus cantans, Ochlerotatus geniculatus and Aedes vexans. The eudominant mosquito species found in the artificial breeding sites are Culex pipiens and the Asian tiger mosquito, Aedes albopictus. Invasive Ae. albopictus, present in the Zagreb area since 2004, has expanded to a larger area of the city during the last three years. The recent emergence of the human West Nile virus and Usutu virus neuroinvasive disease in Zagreb and its surroundings highlighted the role of mosquitoes as vectors of emerging arboviruses. The paper focuses on mosquito species and arboviral infections detected in humans and animals in the Zagreb area, Croatia.

Influence of population diversity on neurovirulence potential of plaque purified L-Zagreb variants.

PubMed

Ivancic-Jelecki, Jelena; Forcic, Dubravko; Jagusic, Maja; Kosutic-Gulija, Tanja; Mazuran, Renata; Balija, Maja Lang; Isakov, Ofer; Shomron, Noam

2016-04-29

Despite continuing research efforts, determinants of mumps virus virulence are still largely unknown. One of consequences of this is difficulty in striking a balance between efficacy and safety of live attenuated mumps vaccines. Among mumps vaccine strains associated with occurrence of postvaccinal aseptic meningitis is L-Zagreb, developed by further attenuation of vaccine strain L-3. Starting from an archived L-Zagreb sample with suboptimal neuroattenuation score, we isolated different viral variants and compared their genetic and phenotypic properties, in investigation of neurovirulence markers. Six different L-Zagreb variants were isolated by plaque purification. Their neurovirulent status was determined by rat-based neurovirulence test; population structure was determined by deep sequencing. We isolated one well neuroattenuated viral variant, two marginally neuroattenuated, and three insufficiently neuroattenuated. No genetic markers of neurovirulence could be identified. None of variants had detectable amounts of defective interfering particles. Two characteristics set insufficiently neuroattenuated variants apart from less-neurovirulent ones: elevated variability level in regions 1293-3314, 5363-7773 and 9382-11657, and/or elevated number of mutations present in frequencies ≥ 1%. The most neurovirulent variants possessed both of these features. Distinctive heterogeneity profiles were obtained for insufficiently neuroattenuated L-Zagreb variants. No markers that would discriminate between marginally and well neuroattenuated variants were identified. The findings of this study may serve as a guideline during development of an improved L3/L-Zagreb vaccine strain. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Pharmacoeconomic indicators of cardiovascular drug utilization in the Republic of Croatia and city of Zagreb in 2008].

PubMed

Stimac, Danijela; Stambuk, Ivanka

2010-12-01

In comparison with original drugs, generic drugs have the same efficacy but considerably lower price and should therefore be preferred to original drugs on prescribing. The aim of the present study was to assess outpatient utilization and rationality of cardiovascular drug prescribing in the City of Zagreb and Republic of Croatia based on the generic to original drug prescribing ratio. Data on the financial indicators and number of cardiovascular drug packages issued in 2008 were obtained from the Croatian Institute of Health Insurance. These data were used to calculate the number of defined daily doses (DDD) and number of DDD per 1000 inhabitants per day (DDD/1000/day). The index of generic/original drug utilization was determined for Zagreb and Croatia as a measure for assessment of prescribing rationality; the significance of difference was determined by X2-test. The rate of prescribing original cardiovascular drugs was significantly higher in Zagreb as compared with Croatia as a whole. The index of prescribing generic versus original drugs was 1.20 (249/208 DDD/1000/day) in Zagreb and 1.65 (249/151 DDD/1000/day) in Croatia. Difference in the utilization of generic drugs between Zagreb and Croatia as determined by X2-test (the level of statistical significance was set at P<0.05) was statistically significant (P=0.021). The highest differences were recorded in the most widely prescribed drug groups, i.e. ACE inhibitors with the generic/original drug index of 1.38 in Zagreb and 2.02 in Croatia; and hypolipemics with the generic/original drug index of 0.96 in Zagreb and 1.34 in Croatia. According to financial indicators, the generic/original drug index was 1.44 in Croatia and only 0.96 in Zagreb. The significantly greater influence of pharmaceutical industry marketing in Zagreb entailed the significantly higher rate of original drug prescribing, which is associated with considerably greater drug expenses. Measures to stimulate prescribing generic drugs should be

Methods of intervention in the control of ragweed spread (Ambrosia artemisiifolia L.) in the area of Zagreb County and the city of Zagreb.

PubMed

Gajnik, Davorin; Peternel, Renata

2009-12-01

The increase in ragweed mediated health problems has led to the development of defense strategies in the countries with the most serious ragweed pollution, namely Hungary, Italy and France. The aim of this paper is to define the frequency of allergic disturbances brought by ragweed pollen in the period between 2002 and 2004, and to devise an action plan for its eradication in the area of Zagreb, as well as in Zagreb County. Thanks to the analysis of common methods of ragweed eradication, even by stating biological ragweed eradication, the best efficiency in ragweed eradication would be achieved through a method that combines several common methods, i.e., a mixed method. In its order on taking measures for obligatory eradication of ragweed, it has stated that the Ministry will ensure funds so that Plant Protection Department in Agriculture and Forestry of the Republic of Croatia, and Department of Herbology of the Faculty of Agriculture of Zagreb could observe the beginning and continuity of ragweed blossom, make an evaluation on the degree of weed overgrowth, establish how widespread it is in the Republic of Croatia, inform the public via the media on control measures and some other duties, but there is no financial help to those who are selected to eradicate ragweed.

Academic profile of students who transferred to Zagreb School of Medicine from other medical schools in Croatia.

PubMed

Dusek, Davorka; Dolovcak, Svjetlana; Kljaković-Gaspić, Marko

2004-02-01

To assess the academic performance of students who transferred to the Zagreb School of Medicine from other three medical schools in Croatia. Academic performance of medical students who moved from Rijeka, Osijek, or Split University Medical Schools to the Zagreb University School of Medicine at the second or third year was compared with academic performance of students enrolled at the Zagreb University School of Medicine. Using the Zagreb Medical School's registry, we made a list of 57 transfer students to Zagreb Medical School in the 1985-1994 period. Control group was formed of students enrolled at the Zagreb School of Medicine in the same period, whose names followed in alphabetical order after the names of transfer students. Students' performance was analyzed according to their grade average before transfer, grade average in the first year after transfer, total grade average after transfer, overall grade average, and duration of studies. We also analyzed the proportion of students in each group who did not pass the admission test at the Zagreb School of Medicine in the year before the enrollment in Zagreb, Osijek, Rijeka, and Split Medical Schools. Nineteen transfer students, transferred between 1985 and 1988, and their controls were excluded from the analysis because of incomplete data. Transfer students had significantly lower grade average before transfer (3.2-/+0.6 vs 3.5-/+0.7, p=0.03, Student t-test), lower grade average in the first year after transfer (3.2-/+0.6 vs 3.5-/+0.7, p=0.03), lower total grade average after transfer (3.6-/+0.5 vs 4.0-/+0.6, p<0.001), and lower overall grade average (3.5-/+0.5 vs 3.9-/+0.6, p<0.001) than control students. Median time to graduate for transfer students was 7 years (range, 5-9) and 6 years (range, 5-9) for control students (p=0.375, Mann-Whitney test). There were significantly more students among transfer students who did not pass the admission test at the Zagreb School of Medicine in the year before the final

Analysis of the high water wave volume for the Sava River near Zagreb

NASA Astrophysics Data System (ADS)

Trninic, Dusan

2010-05-01

The paper analyses volumes of the Sava River high water waves near Zagreb during the period: 1926-2008 (N = 83 years), which is needed for more efficient control of high and flood waters. The primary Sava flood control structures in the City of Zagreb are dikes built on both riverbanks, and the Odra Relief Canal with lateral spillway upstream from the City of Zagreb. Intensive morphological changes in the greater Sava area near Zagreb, and anthropological and climate variations and changes at the Sava catchment up to the Zagreb area require detailed analysis of the water wave characteristics. In one analysis, maximum annual volumes are calculated for high water waves with constant duration of: 10, 20, 30, 40, 50 and 60 days. Such calculations encompass total quantity of water (basic and surface runoff). The log Pearson III distribution is adapted for this series of maximum annual volumes. Based on the results obtained, the interrelations are established between the wave volume as function of duration and occurrence probability. In addition to the analysis of maximum volumes of constant duration, it is interesting to carry out the analyses of maximum volume in excess of the reference discharge since it is very important for the flood control. To determine the reference discharges, a discharge of specific duration is used from an average discharge duration curve. The adopted reference discharges have durations of 50, 40, 30, 20 and 10%. Like in the previous case, log Pearson III distribution is adapted to the maximum wave data series. For reference discharge Q = 604 m3/s (duration 10%), a linear trend is calculated of maximum annual volumes exceeding the reference discharge for the Sava near Zagreb during the analyzed period. The analysis results show a significant decrease trend. A similar analysis is carried out for the following three reference discharges: regular flood control measures at the Sava near Zagreb, which are proclaimed when the water level is 350 cm

[Standardization in laboratory hematology by participating in external quality assurance programs].

PubMed

Nazor, Aida; Siftar, Zoran; Flegar-Mestrić, Zlata

2011-09-01

Since 1985, Department of Clinical Chemistry and Laboratory Medicine, Merkur University Hospital, Zagreb, has been participating in the International External Quality Assessment Scheme for Hematology (IEQAS-H) organized by the World Health Organization (WHO). Owing to very good results, in 1987 the Department received a certificate of participation in this control scheme. Department has been cooperating in the external quality assessment program in laboratory hematology which has been continuously performed in Croatia since 1986 by the Committee for External Quality Assessment Schemes under the auspices of the Croatian Society of Medical Biochemists and School of Pharmacy and Biochemistry, University of Zagreb. Nowadays, 186 medical biochemical laboratories are included in the National External Quality Assessment program, which is performed three times per year. Our Department has participated in the international projects of the European Committee for External Quality Assurance Programs in Laboratory Medicine (EQALM).

Copper in household drinking water in the city of Zagreb, Croatia.

PubMed

Pizent, Alica; Butković, Sanja

2010-09-01

Copper concentration was estimated in tap water samples obtained from 70 households in Zagreb, serviced by a public water supply system. First-draw and flushed samples of tap water were collected in the morning and total copper concentration was determined by graphite furnace atomic absorption spectrometry with Zeeman-effect background correction. We also estimated the contribution of plumbing material to copper concentrations in tap water. In households with copper pipes, median and range copper values were 310 μg L-1 [(27 to 632) μg L-1] in first-draw samples and 16 μg L-1 [(5 to 52) μg L-1] in flushed samples. Corresponding values for households with galvanised pipes were 140 μg L-1 [(11 to 289) μg L-1] and 8 μg L-1 [(1 to 42) μg L-1], respectively. Copper concentrations in household tap water in Zagreb were far below the proposed safe limits set by the Croatian and WHO regulations and EPA standards, and drinking water in Zagreb is not a significant source of copper exposure.

Outpatient utilization of psychopharmaceuticals in the City of Zagreb 2001-2006.

PubMed

Stimac, Danijela; Culig, Josip

2009-03-01

A comprehensive insight into drug utilization as an economic and primarily a public health issue can only be acquired in the context of overall health state of the respective population. The objectives of the study were: 1) to determine the real outpatient utilization of psychopharmaceuticals in Zagreb, 2) to determine the psychopharmaceutical prescribing quality during the study period; and 3) to propose appropriate interventions in Zagreb on the basis of the results obtained. Data on drug utilization were obtained from all Zagreb pharmacies. The number of defined daily doses (DDD) and number of DDD per 1000 inhabitants per day (DDD/1000/day) were calculated from the number of particular drug packages. The Drug Utilization 90% (DU90%) method was used as a criterion of prescribing quality. Outpatient utilization of psychopharmaceuticals showed a declining pattern from 115.40 DDD/1000/day in 2001 to 93.15 DDD/1000/day in 2006. Anxiolytics accounted for the majority of this drug group utilization in the City of Zagreb, although the anxiolytic/antidepressant ratio decreased from 7.19 in 2001 to 3.86 in 2006. The utilization of selective serotonin reuptake inhibitors showed a 2.5-fold increase and accounted for 90% of overall antidepressant utilization. A 2.5-fold decrease was recorded in the utilization of antipsychotics, while the atypical/typical antipsychotic ratio changed from 1:2 in 2001 to 1.1:1 in 2006. Despite some improvement observed in the prescribing quality, the predominance of benzodiazepines in the utilization of psychopharmaceuticals points to the need of additional rationalization in the field.

FORENSIC SCIENCE:: 20 YEARS OF FORENSIC DENTISTRY AT THE UNIVERSITY OF ZAGREB, 1994 - 2014.

PubMed

Brkić, Hrvoje

2014-06-01

Data from available literature point to an early beginning of Forensic Dentistry in Croatia relating to a post-mortem examination of a female patient after a dental procedure in the 1930s. Later on, there were several mass casualties due to collisions and airplane crashes and a railway accident at the Zagreb Main Railway Station wherein the identity of the victims was established based on dental features. Foreign experts in forensics helped identify those victims, particularly forensic dentists because this specialty was almost unknown in our region at the time. During the twenty-year period of the development of Forensic Dentistry at the University of Zagreb, the School of Dental Medicine, the city of Zagreb and Croatia have become internationally recognised on the forensic map of the world.

Willard Libby, Radiocarbon, and Carbon Dating

Science.gov Websites

: Radiocarbon from Pile Graphite; Chemical Methods for Its Concentrations, DOE Technical Report Download Adobe Carbon Dating Chronological Methods 8 - Radiocarbon Dating, University of California, Santa Barbara Why

[Mortality rates of circulatory system diseases and malignant neoplasms in Zagreb population younger than sixty-five--call for alarm].

PubMed

Vizintin, Marina Polić; Mrcela, Nada Tomasović; Kovacić, Luka

2012-12-01

The aim of this work was to analyze the public health indicators for circulatory heart diseases and malignant neoplasms in the population younger than 65 in the City of Zagreb, Croatia, and compare them with the European Union (EU) countries. The purpose was to evaluate the situation and propose the public health preventive measures. The study population were Zagreb citizens aged 0-64 according to the 2001 census. Total Zagreb population was 779145, making 17.6% of total Croatian population. Data from the Croatian Bureau of Statistics and Dr Andrija Stampar Institute of Public Health were used. The standardized 0-64 mortality rates of the selected diseases 2006-2010 were used in the analysis. In 2010, the standardized mortality rates of all analyzed diseases were significantly higher in Zagreb population aged 0-64 than the EU averages except for cervical cancer. In 2010, the mortality rates in Zagreb population aged 0-64 were as follows: circulatory system diseases 61.22, ischemic heart disease 28.99, cerebrovascular diseases 12.51, malignant neoplasms 94.69, tracheal and lung cancer 24.92, breast cancer 21.08 and cervical cancer 2.05. Standardized mortality rates in Zagreb population aged 0-64 for circulatory system were lower than for Croatia (61.22 vs. 63.25), but higher for malignant neoplasms (94.69 vs. 91.2), except for cervical cancer (2.05 vs. 3.14). High standardized mortality rates for the selected diseases in the City of Zagreb, Croatia, were observed. The rates were higher in Zagreb population compared to EU averages except for cervical cancer. This situation urges revision of the public health strategy and implementation of more intensive preventive and screening measures to reduce the risk factors.

Extremal values on Zagreb indices of trees with given distance k-domination number.

PubMed

Pei, Lidan; Pan, Xiangfeng

2018-01-01

Let [Formula: see text] be a graph. A set [Formula: see text] is a distance k -dominating set of G if for every vertex [Formula: see text], [Formula: see text] for some vertex [Formula: see text], where k is a positive integer. The distance k -domination number [Formula: see text] of G is the minimum cardinality among all distance k -dominating sets of G . The first Zagreb index of G is defined as [Formula: see text] and the second Zagreb index of G is [Formula: see text]. In this paper, we obtain the upper bounds for the Zagreb indices of n -vertex trees with given distance k -domination number and characterize the extremal trees, which generalize the results of Borovićanin and Furtula (Appl. Math. Comput. 276:208-218, 2016). What is worth mentioning, for an n -vertex tree T , is that a sharp upper bound on the distance k -domination number [Formula: see text] is determined.

Pre- and post-bomb radiocarbon in fish otoliths

NASA Astrophysics Data System (ADS)

Kalish, John M.

1993-02-01

Measurements of radiocarbon in seawater dissolved inorganic carbon (DIC), or suitable proxies such as hermatypic corals, are a valuable source of information on carbon flux and ocean circulation. However, knowledge of the global distribution of both pre- and post-bomb radiocarbon is limited due to the sources of these data. Suitable hermatypic corals are restricted to shallow tropical and subtropical waters and oceanographic collections of seawater are prohibitively expensive. What is needed is a proxy for ocean radiocarbon that can be collected at most latitudes and depths, and which can be reliably aged. Here I report accelerator mass spectrometry analyses of radiocarbon from selected regions of fish otoliths and show that such measurements are suitable for determining both pre- and post-bomb radiocarbon in all oceans and at most depths. Radiocarbon data obtained from otoliths can extend our knowledge of carbon flux in the oceans and atmosphere and help to develop further understanding of the fate of atmospheric CO 2 and ocean circulation. The data presented here represent the first pre- and post-bomb time series of radiocarbon levels from temperate waters. Furthermore, I demonstrate that the dramatic increase in radiocarbon in the atmosphere and oceans, attributable to the atmospheric testing of thermonuclear bombs during the 1950's and 1960's, provides a chemical mark on fish otoliths that is suitable for the validation of age in fishes.

New radiocarbon measurement methods in the Hertelendi Laboratory, Hungary

NASA Astrophysics Data System (ADS)

Janovics, Róbert; Major, István; Rinyu, László; Veres, Mihály; Molnár, Mihály

2013-04-01

In this paper we present two very different and novel methods for C-14 measurement from dissolved inorganic carbonate (DIC) of water samples. A new LSC sample preparation method for liquid scintillation C-14 measurements was implemented in the ATOMKI. The first method uses direct absorption into a special absorbent (Carbosorb E®) and a following liquid scintillation measurement. Typical sample size is 20-40 litre of water. The developed CO2 absorption method is fast, and simple. The C-14 activities is measured by an ultra low background LSC (TRI-CARB 3170 TR/SL, Perkin Elmer) including quenching parameter (tSIE).The corresponding limit of C-14 dating is 31200 year. Several tests were executed with old borehole CO2 gas without significant content of C-14 and also performed on samples of known C-14 activities between 29 and 7000 pMC, previously measured by GPC. The combined uncertainty of the described determination is about 2 % in the case of recent carbon. It is a very cost-effective and easy to use method based on a novel and simple static absorption process for the CO2 extracted from groundwater. The other very sensitive method is based on accelerator mass spectrometry (AMS) using gas ion source. This method does not require graphite generation and a small volume of water sample (1-20mL) is enough for the radiocarbon measurement. The procedure is very similar to pre-treatment of carbonate contained sample preparation for stable isotope measurement with gasbench technique. We applied a MICADAS type accelerator mass spectrometry (AMS) with gas ion source for C-14 analysis. The radiocarbon content of water was sat free with phosphoric acid and then the headspace gas was rinsed vials. The whole measurement needs only 20 min of each sample. The precision of measurement is better than 1% for modern samples. The preparation is vastly reduced compared to the other AMS methods and principally allows fully automated measurements of groundwater samples with an auto

A Novel/Old Modification of the First Zagreb Index.

PubMed

Ali, Akbar; Trinajstić, Nenad

2018-03-14

In the seminal paper [I. Gutman, N. Trinajstić, Chem. Phys. Lett. 1972, 17, 535-538], it was shown that total electron energy (Eπ ) of any alternant hydrocarbon depends on the sum of the squares of the degrees of the corresponding molecular graph. Nowadays, this sum is known as the first Zagreb index. In the same paper, another molecular descriptor was proved to influence Eπ , but that descriptor was never restudied explicitly. We call this descriptor as modified first Zagreb connection index and denote it by ZC1* . In this paper, chemical applicability of the molecular descriptor ZC1* is tested for the octane isomers. Some basic properties of ZC1* are also established here. Furthermore, the alkanes with maximum and minimum ZC1* values are determined from the class of all alkanes having fixed number of carbon atoms. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Radiocarbon dating of open systems with bomb effect

NASA Technical Reports Server (NTRS)

Mckay, C. P.; Long, A.; Friedmann, E. I.

1986-01-01

The application of radiocarbon dating is extended to include systems that are slowly exchanging carbon with the atmosphere. Simple formulae are derived that relate the true age and the exchange rate of carbon to the apparent radiocarbon age. A radiocarbon age determination does not give a unique true age and exchange rate but determines a locus of values bounded by a minimum age and a minimum exchange rate. It is found that for radiocarbon ages as large as 10,000 years it is necessary to correct for the anthropogenic radiocarbon produced in the atmosphere by nuclear weapons testing. A one-term exponential approximation, with an e-folding time of 14.43 years, is used to model this effect and is shown to be accurate to within 3 percent for exchange time constants of 100 years and greater. The approach developed here is not specific to radiocarbon and can be applied to other radioisotopes in open systems.

Outpatient consumption of antibiotics in the City of Zagreb (2006-2010).

PubMed

Golub, Anja; Štimac, Danijela

2014-02-01

To investigate outpatient consumption of antibiotics during the 2006-2010 period in the City of Zagreb and compare it with other European countries. Data on outpatient consumption of antibiotics were obtained from all pharmacies in the City of Zagreb. Based on the data obtained, the number of defined daily doses per 1000 inhabitants per day (DDDs/TID) were calculated for each ATC subgroup. Drug Utilization 90% (DU90%) method and ratio indicators were used for the assessment of drug prescribing quality. During the period of five years total antibiotics consumption has declined from 37.38 DDDs/TID in 2006 to 33.28 DDDs/ TID in 2010. The most frequently prescribed subgroup was penicillins (J01C). DU90% segment included 10 out of a total of 32 antibiotics in the year 2006 and 10 out of a total of 23 antibiotics in the year 2010. Leading position in the consumption, in 2006 and 2010, was held by broad-spectrum antibiotics, moreover their consumption increased in 2010. Consumption of antibiotics in Zagreb is still very high and is similar to the consumption in European countries with the highest consumption of antibiotics. Reduced consumption of narrow-spectrum antibiotics and unjustified increase in the consumption of broad-spectrum antibiotics suggess that physicians do not follow clinical guidelines.

Si-Traceable Scale for Measurements of Radiocarbon Concentration

NASA Astrophysics Data System (ADS)

Hodges, Joseph T.; Fleisher, Adam J.; Liu, Qingnan; Long, David A.

2017-06-01

Radiocarbon (^{14}C) dating of organic materials is based on measuring the ^{14}C/^{12}C atomic fraction relative to the nascent value that existed when the material was formed by photosynthetic conversion of carbon dioxide present in the atmosphere. This field of measurement has numerous applications including source apportionment of anthropogenic and biogenic fuels and combustion emissions, carbon cycle dynamics, archaeology, and forensics. Accelerator mass spectrometry (AMS) is the most widely used method for radiocarbon detection because it can measure extremely small amounts of radiocarbon (background of nominally 1.2 parts-per-trillion) with high relative precision (0.4 %). AMS measurements of radiocarbon are typically calibrated by reference to standard oxalic-acid (C_2H_2O_4) samples of known radiocativity that are derived from plant matter. Specifically, the internationally accepted absolute dating reference for so-called "modern-equivalent" radiocarbon is 95 % of the specific radioactivity in AD 1950 of the National Bureau of Standards (NBS) oxalic acid standard reference material and normalized to δ^{13}C_{VPDB} = 19 per mil. With this definition, a "modern-equivalent" corresponds to 1.176(70) parts-per-trillion of ^{14}C relative to total carbon content. As an alternative radiocarbon scale, we propose an SI-traceable method to determine ^{14}C absolute concentration which is based on linear Beer-Lambert-law absorption measurements of selected ^{14}C^{16}O_2 ν_3-band line areas. This approach is attractive because line intensities of chosen radiocarbon dioxide transitions can be determined by ab initio calculations with relative uncertainties below 0.5 %. This assumption is justified by the excellent agreement between theoretical values of line intensities and measurements for stable isotopologues of CO_2. In the case of cavity ring-down spectroscopy (CRDS) measurements of ^{14}C^{16}O_2 peak areas, we show that absolute, SI-traceable concentrations of

[Assessing research productivity in Department of Internal Medicine, University of Zagreb, School of Medicine and University Hospital Centre Zagreb].

PubMed

Petrak, Jelka; Sember, Marijan; Granić, Davorka

2012-01-01

Bibliometric analysis may give an objective information about publishing activity, citation rate and collaboration patterns of individuals, groups and institutions. The publication productivity of the present medical staff (79 with specialist degree and 22 residents) in Department of Internal Medicine, University of Zagreb School of Medicine in University Hospital Centre Zagreb was measured by the number of papers indexed by Medline, their impact was measured by the number of times these papers had subsequently been cited in the medical literature, while the collaboration pattern was estimated by the authors' addresses listed in the papers. PubMed database was a source for verifying the bibliographic data, and the citation data were searched via Thomson Web of Scence (WoS) platform. There were a total of 1182 papers, published from 1974 to date. The number of papers per author ranged from 0 to 252. Sixty of papers were published in English, and 39% in Croatian language. The roughly equal share was published in local and foreign journals. The RCT studies and practice guidelines were among the most cited papers and were at the same time published by the highly ranked journals. The collaboration analysis confirmed the extensive involment in the international multicentric clinical trials as well as in the development of international/local practice guidelines.

Radiocarbon Dating the Anthropocene

NASA Astrophysics Data System (ADS)

Chaput, M. A.; Gajewski, K. J.

2015-12-01

The Anthropocene has no agreed start date since current suggestions for its beginning range from Pre-Industrial times to the Industrial Revolution, and from the mid-twentieth century to the future. To set the boundary of the Anthropocene in geological time, we must first understand when, how and to what extent humans began altering the Earth system. One aspect of this involves reconstructing the effects of prehistoric human activity on the physical landscape. However, for global reconstructions of land use and land cover change to be more accurately interpreted in the context of human interaction with the landscape, large-scale spatio-temporal demographic changes in prehistoric populations must be known. Estimates of the relative number of prehistoric humans in different regions of the world and at different moments in time are needed. To this end, we analyze a dataset of radiocarbon dates from the Canadian Archaeological Radiocarbon Database (CARD), the Palaeolithic Database of Europe and the AustArch Database of Australia, as well as published dates from South America. This is the first time such a large quantity of dates (approximately 60,000) has been mapped and studied at a global scale. Initial results from the analysis of temporal frequency distributions of calibrated radiocarbon dates, assumed to be proportional to population density, will be discussed. The utility of radiocarbon dates in studies of the Anthropocene will be evaluated and potential links between population density and changes in atmospheric greenhouse gas concentrations, climate, migration patterning and fire frequency coincidence will be considered.

Computer laboratory in medical education for medical students.

PubMed

Hercigonja-Szekeres, Mira; Marinović, Darko; Kern, Josipa

2009-01-01

Five generations of second year students at the Zagreb University School of Medicine were interviewed through an anonymous questionnaire on their use of personal computers, Internet, computer laboratories and computer-assisted education in general. Results show an advance in students' usage of information and communication technology during the period from 1998/99 to 2002/03. However, their positive opinion about computer laboratory depends on installed capacities: the better the computer laboratory technology, the better the students' acceptance and use of it.

Atmospheric conditions during high ragweed pollen concentrations in Zagreb, Croatia.

PubMed

Prtenjak, Maja Telišman; Srnec, Lidija; Peternel, Renata; Madžarević, Valentina; Hrga, Ivana; Stjepanović, Barbara

2012-11-01

We examined the atmospheric conditions favourable to the occurrence of maximum concentrations of ragweed pollen with an extremely high risk of producing allergy. Over the 2002-2009 period, daily pollen data collected in Zagreb were used to identify two periods of high pollen concentration (> 600 grains/m(3)) for our analysis: period A (3-4 September 2002) and period B (6-7 September 2003). Synoptic conditions in both periods were very similar: Croatia was under the influence of a lower sector high pressure system moving slowly eastward over Eastern Europe. During the 2002-2009 period, this type of weather pattern (on ~ 70% of days), in conjunction with almost non-gradient surface pressure conditions in the area (on ~ 30% of days) characterised days when the daily pollen concentrations were higher than 400 grains/m(3). Numerical experiments using a mesoscale model at fine resolution showed successful multi-day simulations reproducing the local topographic influence on wind flow and in reasonable agreement with available observations. According to the model, the relatively weak synoptic flow (predominantly from the eastern direction) allowed local thermal circulations to develop over Zagreb during both high pollen episodes. Two-hour pollen concentrations and 48-h back-trajectories indicated that regional-range transport of pollen grains from the central Pannonian Plain was the cause of the high pollen concentrations during period A. During period B, the north-westward regional-range transport in Zagreb was supplemented significantly by pronounced horizontal recirculation of pollen grains. This recirculation happened within the diurnal local circulation over the city, causing a late-evening increase in pollen concentration.

Atmospheric conditions during high ragweed pollen concentrations in Zagreb, Croatia

NASA Astrophysics Data System (ADS)

Prtenjak, Maja Telišman; Srnec, Lidija; Peternel, Renata; Madžarević, Valentina; Hrga, Ivana; Stjepanović, Barbara

2012-11-01

We examined the atmospheric conditions favourable to the occurrence of maximum concentrations of ragweed pollen with an extremely high risk of producing allergy. Over the 2002-2009 period, daily pollen data collected in Zagreb were used to identify two periods of high pollen concentration (> 600 grains/m3) for our analysis: period A (3-4 September 2002) and period B (6-7 September 2003). Synoptic conditions in both periods were very similar: Croatia was under the influence of a lower sector high pressure system moving slowly eastward over Eastern Europe. During the 2002-2009 period, this type of weather pattern (on ~ 70% of days), in conjunction with almost non-gradient surface pressure conditions in the area (on ~ 30% of days) characterised days when the daily pollen concentrations were higher than 400 grains/m3. Numerical experiments using a mesoscale model at fine resolution showed successful multi-day simulations reproducing the local topographic influence on wind flow and in reasonable agreement with available observations. According to the model, the relatively weak synoptic flow (predominantly from the eastern direction) allowed local thermal circulations to develop over Zagreb during both high pollen episodes. Two-hour pollen concentrations and 48-h back-trajectories indicated that regional-range transport of pollen grains from the central Pannonian Plain was the cause of the high pollen concentrations during period A. During period B, the north-westward regional-range transport in Zagreb was supplemented significantly by pronounced horizontal recirculation of pollen grains. This recirculation happened within the diurnal local circulation over the city, causing a late-evening increase in pollen concentration.

Geodetic, Geologic and Seismic Interdisciplinary Research of Tectonically Caused Movements in the Wider Area of the City of Zagreb

NASA Astrophysics Data System (ADS)

Dapo, A.; Pribicevic, B.; Herak, M.; Prelogovic, E.

2012-04-01

Since the last great earthquake in 1880 which shook the Zagreb area with IX° MCS, tectonic movements and models of numerous Zagreb faults have been the focal point of Croatian geologists, seismologists and in the last 15 years also geodetic scientists, who all have been working in the scope of their scientific branches on bringing the light to the tectonic mechanisms in the wider Zagreb area. Since it is tectonically very active area and being the Capitol city of the Croatia with very high population density it is of utmost importance to understand those mechanisms and to according to them find the best possible measures for protecting people and valuables. Best results are certainly going to be achieved through the interdisciplinary approach. That is why this paper presents first interdisciplinary results from geodetic, geologic and seismic researches and their contribution to the collective knowledge about tectonic movements in the wider area of the City of Zagreb.

RADIOCARBON SOURCE APPORTIONMENT IN A BIOFUELS ERA

EPA Science Inventory

Biofuels (gasohol and biodiesel) introduce radiocarbon into the U.S. mobile source fuel supply where it was previously absent. Initial measurements of radiocarbon in the PM_2.5 combustion emissions from engines using gasohol indicate that this may have less effect on r...

Caries prevalence among schoolchildren in Zagreb, Croatia.

PubMed

Dukić, Walter; Delija, Barbara; Lulić Dukić, Olga

2011-12-15

To investigate the prevalence of dental caries and treatment needs in schoolchildren aged 7-14 years from Zagreb. Dental examinations based on the World Health Organization criteria were performed on 1168 children in the period 2009-2010. The teeth were clinically examined with standard dental instruments using visual-tactile method under standard dental light. We recorded the clinical indexes of decayed, missed, and filled teeth (DMFT and dmft; upper-case letters refer to permanent and lower-case letters to primary teeth) and decayed, missed, and filled surfaces (DMFS), as well as the significant caries index (SiC). The median DMFT and DMFS of all children were 3 and 4, respectively. The median DMFT and DMFS of 12-year-old children were 4 and 5, respectively. The highest median DMFT score of 7 was found among 14-year-old children. There was a significant difference between age groups (7-10 years and 11-14 years) in DMFT and DMFS. Among 8-year-old children, the median dmft index was the highest (5.5) and SiC index was 7.4. As far as the location of caries on the surface of the first permanent molar is concerned, caries occurred mostly in the central occlusal surface (27.6%). Our results showed a high caries prevalence among schoolchildren in Zagreb, indicating a need for an extensive program of primary oral health care.

Learning Wellness: A Water Exercise Class in Zagreb, Croatia

ERIC Educational Resources Information Center

Roberson, Donald N., Jr.

2007-01-01

The research reported in this article investigated the dynamics of a water exercise class with older adults in Zagreb, Croatia. It focused on 3 classes of older swimmers at a community exercise center. A total of 105 participants were asked to complete a short questionnaire. The questionnaire contained items on demographics, use of free time, and…

Horizontal transmission of the Leningrad-Zagreb mumps vaccine strain: a report of six symptomatic cases of parotitis and one case of meningitis.

PubMed

Atrasheuskaya, Alina; Kulak, Mikhail; Fisenko, Elena G; Karpov, Igor; Ignatyev, George; Atrasheuskaya, Alena

2012-08-03

Here we report horizontal symptomatic transmission of the Leningrad-Zagreb (L-Zagreb) mumps vaccine virus. Children who were the source of transmission had been vaccinated with the MMR vaccine (Serum Institute of India) contained L-Zagreb mumps virus. This is the first report of horizontal symptomatic transmission of this vaccine. The etiology of all seven contact cases was confirmed by epidemiological linking, serology and by F, SH, NP and HN mumps virus genes sequencing. Copyright © 2012 Elsevier Ltd. All rights reserved.

An outbreak of haemorrhagic fever with renal syndrome linked with mountain recreational activities in Zagreb, Croatia, 2017.

PubMed

Lovrić, Z; Kolarić, B; Kosanović Ličina, M L; Tomljenović, M; Đaković Rode, O; Danis, K; Kaić, B; Tešić, V

2018-05-16

In 2017 Zagreb faced the largest outbreak of haemorrhagic fever with renal syndrome (HFRS) to date. We investigated to describe the extent of the outbreak and identify risk factors for infection. We compared laboratory-confirmed cases of Hantavirus infection in Zagreb residents with the onset of illness after 1 January 2017, with individually matched controls from the same household or neighbourhood. We calculated adjusted matched odds ratios (amOR) using conditional logistic regression. During 2017, 104 cases were reported: 11-81 years old (median 37) and 71% (73) male. Compared with 104 controls, cases were more likely to report visiting Mount Medvednica (amOR 60, 95% CI 6-597), visiting a forest (amOR 46, 95% CI 4.7-450) and observing rodents (amOR 20, 95% CI 2.6-159). Seventy per cent of cases (73/104) had visited Mount Medvednica prior to infection. Among participants who had visited Mount Medvednica, cases were more likely to have drunk water from a spring (amOR 22, 95% CI 1.9-265), observed rodents (amOR 17, 95% CI 2-144), picked flowers (amOR 15, 95% CI 1.2-182) or cycled (amOR 14, 95% CI 1.6-135). Our study indicated that recreational activity around Mount Medvednica was associated with HFRS. We recommend enhanced surveillance of the recreational areas during an outbreak.

Ocular related emergencies in Zagreb University Hospital Centre--ten month analysis.

PubMed

Skegro, Ivan; Kordić, Rajko; Kuzman, Tomislav; Perić, Sanja; Kutija, Marija Barisić; Jandroković, Sonja; Jukić, Tomislav

2013-04-01

To determine number, demographic characteristics and presenting symptoms of patients admitted to Emergency ophthalmologic department of Zagreb University hospital centre. Prospective analysis of data of 743 patients admitted to Emergency ophthalmologic department of University hospital centre Zagreb during period of 10 month. Main presenting symptoms at admission were red eye, pain and foreign body sensation. 64% of all patients admitted to emergency unit were male. Almost 40% of them were between 20 and 40 years of age. In female population majority is between 50 and 60 years old (19.33%). The study shows that the most frequent reason for admission in emergency ophthalmic unit is red eye, pain and foreign body sensation. These symptoms were present most frequently in young male patients. Considering fact of their working ability, data can suggest that they don't comply with occupational safety measures. Further research in this direction is needed.

Caries prevalence among schoolchildren in Zagreb, Croatia

PubMed Central

Dukić, Walter; Delija, Barbara; Lulić Dukić, Olga

2011-01-01

Aim To investigate the prevalence of dental caries and treatment needs in schoolchildren aged 7-14 years from Zagreb. Methods Dental examinations based on the World Health Organization criteria were performed on 1168 children in the period 2009-2010. The teeth were clinically examined with standard dental instruments using visual-tactile method under standard dental light. We recorded the clinical indexes of decayed, missed, and filled teeth (DMFT and dmft; upper-case letters refer to permanent and lower-case letters to primary teeth) and decayed, missed, and filled surfaces (DMFS), as well as the significant caries index (SiC). Results The median DMFT and DMFS of all children were 3 and 4, respectively. The median DMFT and DMFS of 12-year-old children were 4 and 5, respectively. The highest median DMFT score of 7 was found among 14-year-old children. There was a significant difference between age groups (7-10 years and 11-14 years) in DMFT and DMFS. Among 8-year-old children, the median dmft index was the highest (5.5) and SiC index was 7.4. As far as the location of caries on the surface of the first permanent molar is concerned, caries occurred mostly in the central occlusal surface (27.6%). Conclusion Our results showed a high caries prevalence among schoolchildren in Zagreb, indicating a need for an extensive program of primary oral health care. PMID:22180264

Sample preparation for radiocarbon ( 14C) measurements of carbonyl compounds in the atmosphere . quantifying the biogenic contribution

NASA Astrophysics Data System (ADS)

Larsen, B. R.; Brussol, C.; Kotzias, D.; Veltkamp, T.; Zwaagstra, O.; Slanina, J.

A method has been developed for the preparation of samples for radiocarbon ( 14C) measurements of carbonyl compounds in the atmosphere. Sampling on 25 ml 2,4-dinitrophenylhydrazine (DNPH)- coated silica gel cartridges can be carried out with up to 10.000 ℓ of ambient air with no adverse effects on sample integrity. Methods for the selective clean-up of the extracts have been investigated. This is a necessary step in preparing ambient carbonyl samples for a measurement of the radiocarbon ( 14C) content. The method which gave the best results include extraction of the DNPH cartridge with CH 3CN and purification of the carbonyl hydrazones over activated silica gel to remove excess DNPH and non target compounds. This method has been validated with laboratory samples and has been proved to give reliable results The radiocarbon data from the first field experiment showed that ambient air over a semi-rural test site in Ispra, Italy on a late summer day contained mainly five carbonyls (formaldehyde>acetaldehyde>acetone>propanal>butanal) of a mixed biogenic (41-57%) and anthropogenic (43-59%) origin. The method will be used in future monitoring of radiocarbon ( 14C) on a number of test sites in Europe.

[The establishment of Medical school in Zagreb in World War I].

PubMed

Dugački, Vlatka; Regan, Krešimir

2015-11-01

World War I irrevocably changed the face of the world, including Croatia and its capital Zagreb. While between 1880 and 1910 Zagreb became a modern European city, World War I (1914-1918) was marked by new municipal regulations that overturned the everyday life of the city. Social conditions reached catastrophic proportions, especially in the later years of the war. Soldiers and refugees swarmed the city, and famine and the Spanish flu epidemic hit it hard. In such harsh social and economic circumstances Milan Rojc, head of the Theology and Education Department and three doctors from the Sisters of Mercy Hospital, namely, Theodor Wikerhauser, Miroslav Čačković pl. Vrhovinski, and Dragutin Mašek, finally started the School of Medicine in December 1917. The School had formally been founded 43 years before, on January 5th, 1874., when the Croatian Parliament, passed the law concerning the establishment of the University, which was to have four faculties: Theology, Philosophy, Law, and Medicine.

Radiocarbon dating of twentieth century works of art

NASA Astrophysics Data System (ADS)

Petrucci, F.; Caforio, L.; Fedi, M.; Mandò, P. A.; Peccenini, E.; Pellicori, V.; Rylands, P.; Schwartzbaum, P.; Taccetti, F.

2016-11-01

The atmospheric tests of nuclear weapons caused a sudden increase in the radiocarbon concentration in the atmosphere from 1955, reaching its maximum value in 1963-1965. Once the nuclear tests in the atmosphere were halted, the 14C concentration started to decrease. This behavior of the radiocarbon concentration is called the "Bomb Peak", and it has successfully been used as a tool for high-precision radiocarbon measurements, in forensic sciences and biology. In the art field, the possibility of dating canvas, wood and paper, widely used as supports for paintings, may be an invaluable tool in modern art studies.

Impact of fossil fuel emissions on atmospheric radiocarbon and various applications of radiocarbon over this century.

PubMed

Graven, Heather D

2015-08-04

Radiocarbon analyses are commonly used in a broad range of fields, including earth science, archaeology, forgery detection, isotope forensics, and physiology. Many applications are sensitive to the radiocarbon ((14)C) content of atmospheric CO2, which has varied since 1890 as a result of nuclear weapons testing, fossil fuel emissions, and CO2 cycling between atmospheric, oceanic, and terrestrial carbon reservoirs. Over this century, the ratio (14)C/C in atmospheric CO2 (Δ(14)CO2) will be determined by the amount of fossil fuel combustion, which decreases Δ(14)CO2 because fossil fuels have lost all (14)C from radioactive decay. Simulations of Δ(14)CO2 using the emission scenarios from the Intergovernmental Panel on Climate Change Fifth Assessment Report, the Representative Concentration Pathways, indicate that ambitious emission reductions could sustain Δ(14)CO2 near the preindustrial level of 0‰ through 2100, whereas "business-as-usual" emissions will reduce Δ(14)CO2 to -250‰, equivalent to the depletion expected from over 2,000 y of radioactive decay. Given current emissions trends, fossil fuel emission-driven artificial "aging" of the atmosphere is likely to occur much faster and with a larger magnitude than previously expected. This finding has strong and as yet unrecognized implications for many applications of radiocarbon in various fields, and it implies that radiocarbon dating may no longer provide definitive ages for samples up to 2,000 y old.

Impact of fossil fuel emissions on atmospheric radiocarbon and various applications of radiocarbon over this century

PubMed Central

Graven, Heather D.

2015-01-01

Radiocarbon analyses are commonly used in a broad range of fields, including earth science, archaeology, forgery detection, isotope forensics, and physiology. Many applications are sensitive to the radiocarbon (14C) content of atmospheric CO2, which has varied since 1890 as a result of nuclear weapons testing, fossil fuel emissions, and CO2 cycling between atmospheric, oceanic, and terrestrial carbon reservoirs. Over this century, the ratio 14C/C in atmospheric CO2 (Δ14CO2) will be determined by the amount of fossil fuel combustion, which decreases Δ14CO2 because fossil fuels have lost all 14C from radioactive decay. Simulations of Δ14CO2 using the emission scenarios from the Intergovernmental Panel on Climate Change Fifth Assessment Report, the Representative Concentration Pathways, indicate that ambitious emission reductions could sustain Δ14CO2 near the preindustrial level of 0‰ through 2100, whereas “business-as-usual” emissions will reduce Δ14CO2 to −250‰, equivalent to the depletion expected from over 2,000 y of radioactive decay. Given current emissions trends, fossil fuel emission-driven artificial “aging” of the atmosphere is likely to occur much faster and with a larger magnitude than previously expected. This finding has strong and as yet unrecognized implications for many applications of radiocarbon in various fields, and it implies that radiocarbon dating may no longer provide definitive ages for samples up to 2,000 y old. PMID:26195757

Stability of the Zagreb realization of the Carnegie-Mellon-Berkeley coupled-channels unitary model

NASA Astrophysics Data System (ADS)

Osmanović, H.; Ceci, S.; Švarc, A.; Hadžimehmedović, M.; Stahov, J.

2011-09-01

In Hadžimehmedović [Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.84.035204 84, 035204 (2011)] we have used the Zagreb realization of Carnegie-Melon-Berkeley coupled-channel, unitary model as a tool for extracting pole positions from the world collection of partial-wave data, with the aim of eliminating model dependence in pole-search procedures. In order that the method is sensible, we in this paper discuss the stability of the method with respect to the strong variation of different model ingredients. We show that the Zagreb CMB procedure is very stable with strong variation of the model assumptions and that it can reliably predict the pole positions of the fitted partial-wave amplitudes.

Concept of sustainable waste management in the city of Zagreb: Towards the implementation of circular economy approach.

PubMed

Ribić, Bojan; Voća, Neven; Ilakovac, Branka

2017-02-01

Improvement of the current waste management is one of the main challenges for most municipalities in Croatia, mainly due to legal obligations set in different European Union (EU) directives regarding waste management, such as reduction of waste generation and landfilling, or increase of separately collected waste and recycling rates. This paper highlights the current waste management in the city of Zagreb by analyzing the waste generation, collection, and disposal scenario along with the regulatory and institutional framework. Since the present waste management system mainly depends upon landfilling, with the rate of separate waste collection and recycling far from being adequate, it is necessary to introduce a new system that will take into account the current situation in the city as well as the obligations imposed by the EU. Namely, in the coming years, the Waste Framework and Landfill Directives of the European Union will be a significant driver of change in waste management practices and governance of the city of Zagreb. At present, the yearly separate waste collection makes somewhat less than 5 kg per capita of various waste fractions, i.e., far below the average value for the (28) capital cities of the EU, which is 108 kg per capita. This is possible to achieve only by better and sustainable planning of future activities and facilities, taking into account of environmental, economic, and social aspects of waste management. This means that the city of Zagreb not only will have to invest in new infrastructure to meet the targets, but also will have to enhance public awareness in diverting this waste at the household level. The solution for the new waste management proposed in this paper will certainly be a way of implementing circular economy approach to current waste management practice in the city of Zagreb. Municipal waste management in the developing countries in the EU (new eastern EU members) is often characterized by its limited utilization of recycling

The radiocarbon hydroxyl technique

NASA Technical Reports Server (NTRS)

Campbell, Malcolm J.; Sheppard, John C.

1994-01-01

The Radiocarbon Technique depends upon measuring the rate of oxidation of CO in an essentially unperturbed sample of air. The airborne technique is slightly different. Hydroxyl concentrations can be calculated directly; peroxyl concentrations can be obtained by NO doping.

Secular trend of menarche in Zagreb (Croatia) adolescents.

PubMed

Veček, Nenad; Veček, Andrea; Zajc Petranović, Matea; Tomas, Zeljka; Arch-Veček, Branka; Skarić-Jurić, Tatjana; Miličić, Jasna

2012-01-01

To study the secular trend of menarche in high-school urban adolescent girls (Zagreb, Croatia) over the last two decades, and to evaluate the possible impact of worsening of socio-economic conditions on age at menarche during the Croatian War of Independence (1991-1995). Three surveys of female adolescents aged 15-19 years: (a) 523 girls interviewed in 1990, (b) 888 girls interviewed in 1997, and (c) 399 girls interviewed in 2010. Self-reported age at menarche (in decimal years) was presented by age groups and year of interview. Differences in mean age at menarche between adolescent age groups as well as between surveys were tested using One-way ANOVA. The mean age at menarche was 12.82 years in 1990, 12.92 years in 1997 and 12.31 years in 2010. It increased by 0.10 years from 1990 to 1997 (p=0.290) and then declined by 0.61 years from 1997 to 2010 (p<0.001). Over the 20-year period, the overall mean age at menarche declined by 0.51 years (p<0.001). The age at menarche in Zagreb adolescents continued to decline significantly from 1990 to 2010 (p<0.001), in spite of a statistically insignificant initial increase between 1990 and 1997. When put in broader context, age at menarche mirrored socio-economic changes in the war period. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

The Zagreb Collection of human brains: a unique, versatile, but underexploited resource for the neuroscience community.

PubMed

Judaš, Miloš; Šimić, Goran; Petanjek, Zdravko; Jovanov-Milošević, Nataša; Pletikos, Mihovil; Vasung, Lana; Vukšić, Mario; Kostović, Ivica

2011-05-01

The Zagreb Collection of developing and adult human brains was founded in 1974 by Ivica Kostović and consists of 1,278 developing and adult human brains, including 610 fetal, 317 children, and 359 adult brains. It is one of the largest collections of developing human brains. The collection serves as a key resource for many focused research projects and has led to several seminal contributions on mammalian cortical development, such as the discovery of the transient fetal subplate zone and of early bilaminar synaptogenesis in the embryonic and fetal human cerebral cortex, and the first description of growing afferent pathways in the human fetal telencephalon. The Zagreb Collection also serves as a core resource for ever-growing networks of international collaboration and represents the starting point for many young investigators who now pursue independent research careers at leading international institutions. The Zagreb Collection, however, remains underexploited owing to a lack of adequate funding in Croatia. Funding could establish an online catalog of the collection and modern virtual microscopy scanning methods to make the collection internationally more accessible. © 2011 New York Academy of Sciences.

Creating an Intercultural Learning Opportunity: Zagreb, Croatia and Plattsburgh, New York

ERIC Educational Resources Information Center

Mountcastle, Amy

2011-01-01

In the spring of 2009 I embarked on a teaching experiment in which I joined an online SUNY-Plattsburgh class taking my Anthropology of Human Rights course with a conventional class at the University of Zagreb, Croatia, where I was a visiting professor teaching the same course. My motivations were several, but prominent among them was to test the…

Optimization of simultaneous tritium–radiocarbon internal gas proportional counting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonicalzi, R. M.; Aalseth, C. E.; Day, A. R.

Specific environmental applications can benefit from dual tritium and radiocarbon measurements in a single compound. Assuming typical environmental levels, it is often the low tritium activity relative to the higher radiocarbon activity that limits the dual measurement. In this paper, we explore the parameter space for a combined tritium and radiocarbon measurement using a methane sample mixed with an argon fill gas in low-background proportional counters of a specific design. We present an optimized methane percentage, detector fill pressure, and analysis energy windows to maximize measurement sensitivity while minimizing count time. The final optimized method uses a 9-atm fill ofmore » P35 (35% methane, 65% argon), and a tritium analysis window from 1.5 to 10.3 keV, which stops short of the tritium beta decay endpoint energy of 18.6 keV. This method optimizes tritium counting efficiency while minimizing radiocarbon beta decay interference.« less

Comparing the Palmer Drought Index and the Standardized Precipitation Index for Zagreb-Gric Observatory

NASA Astrophysics Data System (ADS)

Pandzic, Kreso

2016-04-01

Conventional Palmer Drought Index (PDSI) and recent Standardized Precipitation Index (SPI) are compared for Zagreb-Gric weather station. Historical time series of PDSI and SPI are compared. For that purpose monthly precipitation, air temperature and air humidity data for Zagreb-Gric Observatory and period 1862-2012 are used. The results indicate that SPI is simpler for interpretation than PDSI. On the other side, lack of temperature within SPI, make impossible use of it on climate change applications. A comparison of PDSI and SPI for the periods from 1 to 24 months indicate the best agreement between PDSI and SPI for the periods from 6 to 12 months. In addition, correlation coefficients of determination between annual corn crop per hectare and SPI 9- months time scale and PDSI from May to October are shown as significant.

Comparing the Palmer Drought Index and the Standardized Precipitation Index for Zagreb-Gric Observatory

NASA Astrophysics Data System (ADS)

Pandzic, Kreso

2014-05-01

Conventional Palmer Drought Index (PDSI) and recent Standardized Precipitation Index (SPI) are compared for Zagreb-Gric weather station. Historical time series of PDSI and SPI are compared. For that purpose monthly precipitation, air temperature and air humidity data for Zagreb-Gric Observatory and period 1862-2010 are used. The results indicate that SPI is simpler for interpretation than PDI. On the other side, lack of temperature within SPI, make impossible use of it on climate change applications. Further development of both indices is required. Possible applications of them in irrigation scheduling system is considered as well for drought risk assessment. In addition, a comparison of PDSI and SPI for the periods from 1 to 24 months indicate the best agreement between PDSI and SPI for the periods from 6 to 12 months.

Comparison of safety and immunogenicity of purified chick embryo cell vaccine using Zagreb and Essen regimens in patients with category II exposure in China.

PubMed

Hu, Quan; Liu, Man-Qing; Zhu, Zheng-Gang; Zhu, Ze-Rong; Lu, Sha

2014-01-01

The aim was to compare the safety and immunogenicity of purified chick embryo cell vaccine (PCECV) with Zagreb 2-1-1 and Essen 1-1-1-1-1 regimens in patients with WHO category II exposure in China. Side effects including systemic and local symptoms were recorded for all patients during vaccination with purified chick embryo cell vaccine (PCECV) under Zagreb 2-1-1 or Essen 1-1-1-1-1 regimens, and the rabies neutralization antibody titers in patients' serum at days 0, 7, 14, 45, 365 post-immunization were measured to determine the immunogenicity. Fever and pain were the most common events for systemic and local symptoms respectively, and most side effects (86.78%, 105/121) occurred after the first dose of vaccination. Safety analysis showed differences in side effects in<5-year-old patients between Zagreb and Essen regimens, especially after the first dose of vaccination (P = 0.043). Immunogenicity analysis indicated that Zagreb can achieve higher neutralization antibody titers and a greater seroconversion rate in a shorter time but had less persistence than Essen. When compared with the Essen regimen, the Zagreb regimen had a different immunogenicity in all study subjects, and different safety profile in young children, and a further study with a larger population and longer surveillance is warranted.

Ocean science: Radiocarbon variability in the western North Atlantic during the last deglaciation

USGS Publications Warehouse

Robinson, L.F.; Adkins, J.F.; Keigwin, L.D.; Southon, J.; Fernandez, D.P.; Wang, S.-L.; Scheirer, D.S.

2005-01-01

We present a detailed history of glacial to Holocene radiocarbon in the deep western North Atlantic from deep-sea corals and paired benthic-planktonic foraminifera. The deglaciation is marked by switches between radiocarbon-enriched and -depleted waters, leading to large radiocarbon gradients in the water column. These changes played an important role in modulating atmospheric radiocarbon. The deep-ocean record supports the notion of a bipolar seesaw with increased Northern-source deep-water formation linked to Northern Hemisphere warming and the reverse. In contrast, the more frequent radiocarbon variations in the intermediate/deep ocean are associated with roughly synchronous changes at the poles.

Radiocarbon chronology of Black Sea sediments

NASA Astrophysics Data System (ADS)

Jones, Glenn A.; Gagnon, Alan R.

1994-03-01

Accelerator Mass Spectrometer (AMS) radiocarbon analyses have been made on 102 samples from 12 sediment cores and 23 samples from two water column profiles. These materials, collected during the first leg of the 1988 joint U.S.-Turkish Black Sea Expedition, provide the most comprehensive radiocarbon chronology of Black Sea sediments yet attempted. Radiocarbon analyses from carefully collected box cores and a mollusc shell collected live in 1931 suggest the prebomb surface waters had a Δ 14C value of -55% (460 years) and that the maximum detrital correction for radiocarbon ages of Unit I sediments is 580 years for the organic carbon and 260 years for the carbonate fractions. Evidence does not support the 1430-2000 years pre-bomb surface water and/or detrital corrections argued for in past studies. The best estimates for the age of the beginning of the final invasion of the coccolithophore Emiliania huxleyi (Unit 1/2 boundary of Ross and DEGENS, 1974, The Black Sea—geology, chemistry and biology, pp. 183-199) and the age of the first invasion of E. huxeleyi (Unit I/II boundary of HAYet al., 1991, Deep-Sea Research, 38, S1211-S1235) are 1635 ± 60 and 2720 ± 160 years BP, respectively. Sapropel formation began at approximately 7540 ± 130 years BP at all depths in the basin, a pattern in disagreement with those predicted by existing time-evolution models of sapropel formation for this basin. Our data suggest that the oxic-anoxic interface has remained relatively stable throughout the Holocene, is controlled largely by the physical oceanography of the basin, and has not evolved as assumed by previous workers.

Differential extraction of radiocarbon associated with soil biomass and humus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsao, C.W.; Bartha, R.

To detect the humification of organic compounds in soil that bypasses biomass incorporation, selective extraction procedures for radiocarbon from soil biomass and humus were evaluated. Following the incubation of [sup 14]C-glucose and [sup 14]C-benzoate in soil, fumigation--0.5 M K[sub 2]SO[sub 4] extraction and 0.15 M Na[sub 4]P[sub 2]O[sub 7] extraction selectively removed biomass-associated and humus-associated radiocarbon, respectively. Applying the recovery correction of 3.4[times] to biomass and 3.5[times] to humus, radiocarbon balances of 95 to 107% were obtained during a time window following the degradation of these substrates. Negligible overlap between the extractions renders the technique suitable for investigating the fatemore » of organics that, through cometabolism, attain unusual radiocarbon distributions in soil.« less

Bla g 1 allergen levels in Zagreb area household dust.

PubMed

Prester, Ljerka; Macan, Jelena

2011-03-01

Cockroach allergy is a health problem in many parts of the world. In urban environments, indoor exposure to cockroach allergens involves a risk of asthma. The aim of this study was to measure the mass fraction of Bla g 1, a major allergen of the German cockroach (Blatella germanica) in 30 house samples, collected at random from Zagreb area households, Croatia. Dust samples were collected on cellulose filters by vacuuming living rooms floors. After extraction, Bla g 1 was detected using the commercial enzyme-linked immunosorbent assay (ELISA). Only four of the thirty households had detectable Bla g 1 levels, and only in one was its concentration higher than 2.0 U g(-1), the threshold associated with sensitisation. The Bla g 1 ELISA proved highly sensitive, with the detection limit of 0.12 U g(-1). The within- and between-assay imprecision was 8.9 % and 14.4 %, respectively, and accuracy 85 % to 120 %. Low Bla g 1 levels in the household dust support previously reported low prevalence of skin sensitisation to B. germanica among Zagreb residents. Further monitoring should reveal if there are differences in cockroach allergen exposure and sensitisation between households from other geographic areas in Croatia.

Depression and auto-aggressiveness in adolescents in Zagreb.

PubMed

Tripković, Mara; Vuković, Iris Sarajlić; Frančišković, Tanja; Pisk, Sandra Vuk; Krnić, Silvana

2014-12-01

The aim of the study was to explore the frequency of depression among the general population of adolescents who were high school students in the city of Zagreb. As depression is associated with increased suicidal risk we wanted to check to what extent depression, as an emotional problem among youth, is associated with auto-aggression in the general population of adolescents. The study was conducted on a sample of high school students in Zagreb and it included 701 students of both genders aged from 14-19 years of age. To test the depression a Beck Depression Inventory (BDI) was administered for youth between 11-18 years of age (Youth Self Report for ages 11-18). To test auto-aggression a Scale of Auto-destructiveness (SAD) was used. Results obtained by this study show that about 20.7% of high school students have mild and borderline depressive disorders while moderate or severe depression shows about 5% of them, whereby depression is statistically significant among girls who, on average, report more symptoms of depression. It has also been proven a significant impact of depression levels (F (2,423)=35.860, p<0.001) on auto-aggression in subjects of both genders. In both genders, moderately depressed show more auto destructiveness than those without depression symptoms (p<0.01). In the group of heavily depressed (n=30), significantly higher self-destructiveness is shown by girls (p<0.01). The data suggest the importance of early recognition, understanding and treatment of depressive symptoms in adolescents in order to reduce the risk of subsequent chronic psychosocial damage.

Immunological Effect of aGV Rabies Vaccine Administered Using the Essen and Zagreb Regimens: A Double-Blind, Randomized Clinical Trial.

PubMed

Miao, Li; Shi, Liwei; Yang, Yi; Yan, Kunming; Sun, Hongliang; Mo, Zhaojun; Li, Li

2018-04-01

This study evaluated the immunological effect of an aGV rabies virus strain using the Essen and Zagreb immunization programs. A total of 1,944 subjects were enrolled and divided into three groups: the Essen test group, Essen control group, and Zagreb test group. Neutralizing antibody levels and antibody seroconversion rates were determined at 7 and 14 days after the initial inoculations and then 14 days after the final inoculation in all of the subjects. The seroconversion rates for the Essen test group, Essen control group, and Zagreb test group, which were assessed 7 days after the first dosing in a susceptible population, were 35.74%, 26.92%, and 45.49%, respectively, and at 14 days, the seroconversion rates in this population were 100%, 100%, and 99.63%, respectively. At 14 days after the final dosing, the seroconversion rates were 100% in all three of the groups. The neutralizing serum antibody levels of the Essen test group, Essen control group, and Zagreb test group at 7 days after the first dosing in the susceptible population were 0.37, 0.26, and 0.56 IU/mL, respectively, and at 14 days after the initial dosing, these levels were 16.71, 13.85, and 16.80 IU/mL. At 14 days after the final dosing, the neutralizing antibody levels were 22.9, 16.3, and 18.62 IU/mL, respectively. The results of this study suggested that the aGV rabies vaccine using the Essen program resulted in a good serum immune response, and the seroconversion rates and the neutralizing antibody levels generated with the Zagreb regimen were higher than those with the Essen regimen when measured 7 days after the first dose.

The prevalence of idiopathic osteosclerosis and condensing osteitis in Zagreb population.

PubMed

Verzak, Zeljko; Celap, Branka; Modrić, Vesna Erika; Sorić, Pjetra; Karlović, Zoran

2012-12-01

The aim of this study was to determine the prevalence of idiopathic osteosclerosis (IO) and condensing osteitis (CO) in Zagreb patient population sample according to age and sex, localization in the jaw, as well as dental relationship between IO and CO lesions. A retrospective study was performed using orthopantomograms of 1200 patients who underwent dental treatment. Descriptive characteristics of radiopacities, including the size and information concerning the tooth involved, were recorded and processed using chi2-test. A total of 114 radiopacities were identified, 34 IO in 29 subjects (16 female and 13 male, mean age 35), and 80 CO in 69 subjects (38 female and 31 male, mean age 37). There were no significant sex differences. Both CO and IO showed greater predilection for occurrence in the premolar to molar region of the mandible. Our results indicated a low prevalence of IO and CO in the population of Zagreb. Our findings support the theory that IO lesions should be considered developmental variants of normal bone architecture unrelated to local stimuli, whereas CO lesions could be considered reactive formations related to teeth with deep caries, large restoration, or pulpitis.

Transmission of the L-Zagreb mumps vaccine virus, Croatia, 2005-2008.

PubMed

Kaic, B; Gjenero-Margan, I; Aleraj, B; Ljubin-Sternak, S; Vilibic-Cavlek, T; Kilvain, S; Pavic, I; Stojanovic, D; Ilic, A

2008-04-17

We report on three cases of symptomatic transmission of the L-Zagreb mumps vaccine virus from three vaccinated children to five adult contacts. The five contact cases were parents of the vaccinated children and presented with parotitis and in one case also with aseptic meningitis. The etiology of the contacts' illness was determined by viral culture, genomic sequencing, serology and epidemiological linking. Two of the vaccinated children developed vaccine associated parotitis as an adverse event three weeks following immunization. Symptoms in contact cases developed five to seven weeks after the vaccination of the children. The five contact cases, as well as the three children with adverse events recovered completely. The children had been vaccinated with MMR vaccine produced by the Institute of Immunology Zagreb, each of them with a different lot. One of the possible explanations for these adverse events is that the very low levels of wild mumps virus circulation in the last decade, combined with waning immunity in those who received one dose of vaccine or suffered from mumps in childhood, resulted in susceptible young adults and that this unique epidemiological situation allows us to detect horizontal transmission of mumps vaccine virus.

Closed tubes preparation of graphite for high-precision AMS radiocarbon analysis

NASA Astrophysics Data System (ADS)

Hajdas, I.; Michczynska, D.; Bonani, G.; Maurer, M.; Wacker, L.

2009-04-01

Radiocarbon dating is an established tool applied in Geochronology. Technical developments of Accelerator Mass Spectrometry AMS, which allow measurements of samples containing less than 1 mg of carbon, opened opportunities for new applications. Moreover, high resolution records of the past changes require high-resolution chronologies i.e. sampling for 14C dating. In result, the field of applications is rapidly expanding and number of radiocarbon analysis is growing rapidly. Nowadays dedicated 14C AMS machines have great capacity for analysis but in order to keep up with the demand for analysis and provide the results as fast as possible a very efficient way of sample preparation is required. Sample preparation for 14C AMS analysis consists of two steps: separation of relevant carbon from the sample material (removing contamination) and preparation of graphite for AMS analysis. The last step usually involves reaction of CO2 with H2, in the presence of metal catalyst (Fe or Co) of specific mesh size heated to 550-625°C, as originally suggested by Vogel et al. (1984). Various graphitization systems have been built in order to fulfil the requirement of sample quality needed for high-precision radiocarbon data. In the early 90ties another method has been proposed (Vogel 1992) and applied by few laboratories mainly for environmental or biomedical samples. This method uses TiH2 as a source of H2 and can be easily and flexibly applied to produce graphite. Sample of CO2 is frozen in to the tube containing pre-conditioned Zn/TiH2 and Fe catalyst. Torch sealed tubes are then placed in the stepwise heated oven at 500/550°C and left to react for several hours. The greatest problem is the lack of control of the reaction completeness and considerable fractionation. However, recently reported results (Xu et al. 2007) suggest that high precision dating using graphite produced in closed tubes might be possible. We will present results of radiocarbon dating of the set of standards

Changes in the radiocarbon reservoir age in Lake Xingyun, Southwestern China during the Holocene.

PubMed

Zhou, Aifeng; He, Yuxin; Wu, Duo; Zhang, Xiaonan; Zhang, Can; Liu, Zhonghui; Yu, Junqing

2015-01-01

Chronology is a necessary component of paleoclimatology. Radiocarbon dating plays a central role in determining the ages of geological samples younger than ca. 50 ka BP. However, there are many limitations for its application, including radiocarbon reservoir effects, which may cause incorrect chronology in many lakes. Here we demonstrate temporal changes in the radiocarbon reservoir age of Lake Xingyun, Southwestern China, where radiocarbon ages based on bulk organic matter have been reported in previous studies. Our new radiocarbon ages, determined from terrestrial plant macrofossils suggest that the radiocarbon reservoir age changed from 960 to 2200 years during the last 8500 cal a BP years. These changes to the reservoir effect were associated with inputs from either pre-aged organic carbon or 14C-depleted hard water in Lake Xingyun caused by hydrological change in the lake system. The radiocarbon reservoir age may in return be a good indicator for the carbon source in lake ecosystems and depositional environment.

Radiocarbon dating the late Middle Paleolithic and the Aurignacian of the Swabian Jura.

PubMed

Conard, Nicholas J; Bolus, Michael

2008-11-01

Many lines of evidence point to the period between roughly 40 and 30 ka BP as the period in which modern humans arrived in Europe and displaced the indigenous Neandertal populations. At the same time, many innovations associated with the Upper Paleolithic--including new stone and organic technologies, use of personal ornaments, figurative art, and musical instruments--are first documented in the European archaeological record. Dating the events of this period is challenging for several reasons. In the period about six to seven radiocarbon half-lives ago, variable preservation, pre-treatment, and sample preparation can easily lead to a lack of reproducibility between samples and laboratories. A range of biological, cultural, and geological processes can lead to mixing of archaeological strata and their contents. Additionally, some data sets point to this period as a time of significant spikes in levels of atmospheric radiocarbon. This paper assesses these questions in the context of the well-excavated and intensively studied caves of Geissenklösterle and Hohle Fels in the Swabian Jura of southwestern Germany. We conclude that variable atmospheric radiocarbon production contributes to the problems of dating the late Middle Paleolithic and the early Upper Paleolithic. To help establish a reliable chronology for the Swabian Aurignacian, we are beginning to focus our dating program on short-lived, stratigraphically secure features to see if they yield reproducible results. This approach may help to test competing explanations for the noisy and often non-reproducible results that arise when trying to date the transition from the Middle to the Upper Paleolithic.

Predicted net efflux of radiocarbon from the ocean and increase in atmospheric radiocarbon content

NASA Astrophysics Data System (ADS)

Caldeira, Ken; Rau, Greg H.; Duffy, Philip B.

Prior to changes introduced by man, production of radiocarbon (14C) in the stratosphere nearly balanced the flux of 14C from the atmosphere to the ocean and land biosphere, which in turn nearly balanced radioactive decay in these 14C reservoirs. This balance has been altered by land-use changes, fossil-fuel burning, and atmospheric nuclear detonations. Here, we use a model of the global carbon cycle to quantify these radiocarbon fluxes and make predictions about their magnitude in the future. Atmospheric nuclear detonations increased atmospheric 14C content by about 80% by the mid-1960's. Since that time, the 14C content of the atmosphere has been diminishing as this bomb radiocarbon has been entering the oceans and terrestrial biosphere. However, we predict that atmospheric 14C content will reach a minimum and start to increase within the next few years if fossil-fuel burning continues according to a “business-as-usual” scenario, even though fossil fuels are devoid of 14C. This will happen because fossil-fuel carbon diminishes the net flux of 14C from the atmosphere to the oceans and land biosphere, forcing 14C to accumulate in the atmosphere. Furthermore, the net flux of both bomb and natural 14C into the ocean are predicted to continue to slow and then, in the middle of the next century, to reverse, so that there will be a net flux of 14C from the ocean to the atmosphere. The predicted reversal of net 14C fluxes into the ocean is a further example of human impacts on the global carbon cycle.

School health services in the City of Zagreb - do we meet adolescents' needs?

PubMed

Kuzman, Marina; Posavec, Marija; Marić, Ivana

2014-12-01

School health services (SHS) have in Croatia long tradition, established organizational structure, defined program and educated staff. The program is limited to the preventive activities. The aim of the study was to investigate the satisfaction of the children, school staff and parents with existing school health services in the City of Zagreb. The structured questionnaire was sent to the primary and secondary schools in the City of Zagreb, which were selected using random sample method. The questionnaires were anonymous and filled in supervised by class masters. In the secondary schools the structure of schooling was respected. Questionnaires were filled by 448 pupils from primary, 551 from secondary schools, by 596 parents and 595 teachers. In primary schools pupils rated SHS more available and accessible, staff complaisant and responsible, counselling being useful and justified, confidentiality respected higher than pupils from secondary schools (p<0.001). Teachers from primary and secondary schools perceived SHS as valuable school partners (88.9% and 82.3%). Teachers from primary and secondary schools (88.9% and 88.1%) and parents (78.3% and 67.5%) stated that SHS could not be replaced by GPs or paediatricians. Primary school pupils felt that most common problems were injuries and vocational counselling, secondary school pupils assessed behavioural and sexual related problems as mostly challenging. Satisfaction with the SHS response to the most challenging problems was rated higher by teachers from primary schools (p<0.001 for learning difficulties, chronic diseases, bullying and vocational counselling), by parents for learning difficulties and vocational counselling, but no significance was found for pupils' satisfactions. SHS in Zagreb are recognized as vital and necessary partners for schools, available and accessible for pupils, teachers and parents, especially for primary schools. Counselling is highly rated by all respondents, confidentiality considered

Beta-lactam antibiotics during pregnancy: a cross-sectional comparative study Zagreb-Novi Sad.

PubMed

Erić, M; Leppée, M; Sabo, A; Culig, J

2012-01-01

During pregnancy, a number of changes occur in women's body, and some medications are safe and some are not. The aim of our study was to establish the possible correlation between use of beta-lactam antibiotics in pregnancy and occurrence of congenital malformations. The study included 893 pregnant women from Zagreb and 6099 pregnant women from Novi Sad. 527 pregnant women used beta-lactams. First part of the study (one month study) was performed at four maternity hospitals in Zagreb, Croatia. Second part were collected as a part of the study analysing the teratogenicity of drugs used in pregnancy, a longitudinal study performed in Novi Sad district. Pregnant women most frequently used antibacterial agents in the first trimester of pregnancy. They used 15 different antibacterial medications, most often beta-lactams. In Zagreb arm, out of the total number of pregnant women that used medications during pregnancy (859), 231 (26.9%) used beta-lactam antibiotics. Malformations were detected in 8 (3.5%) cases. The prevalence of malformations in newborns whose mothers did not take beta-lactam antibiotics in pregnancy (662) was 2.7% (18 newborns with malformations). In Novi Sad arm, out of the total number of pregnant women that used medications during pregnancy (2013), 296 (14.7%) used beta-lactam antibiotics. Malformations were detected in 14 (4.7%) cases. The prevalence of malformations in newborns whose mothers did not take beta-lactam antibiotics in pregnancy (5803) was 1.7% (99 newborns with malformations). The results show possible teratogenic potential even with those antibacterials which are considered safe (amoxicillin) but as those are usually minor malformations they often pass undetected. International pharmacoepidemiological studies of drug use in pregnancy could substantially contribute to the improvement of pharmacotherapy, and could be of great help in assessing the fetal risks.

137Cs in soil and fallout around Zagreb (Croatia) at the time of the Fukushima accident.

PubMed

Šoštarić, Marko; Petrinec, Branko; Babić, Dinko

2013-12-01

This paper addresses the noticeable increase of 137Cs activity concentrations in soil and fallout in the area surrounding Zagreb (Croatia) that occurred at the time of the 2011 Fukushima accident. This topic is important for public health as 137Cs is highly toxic due to its long half-life of radioactive decay and chemical similarity to potassium. 137Cs concentrations in fallout were much greater than in soil, but remained present longer in the latter. While being detectable in our measurements, 137Cs did not spread through the food chain in amounts exceeding the maximum allowed level of radioactive food contamination. However, more thorough and consistent measurements need to be done in order to establish the precise activity trends of 137Cs in Zagreb soil and fallout.

The Worldwide Marine Radiocarbon Reservoir Effect: Definitions, Mechanisms, and Prospects

NASA Astrophysics Data System (ADS)

Alves, Eduardo Q.; Macario, Kita; Ascough, Philippa; Bronk Ramsey, Christopher

2018-03-01

When a carbon reservoir has a lower radiocarbon content than the atmosphere, this is referred to as a reservoir effect. This is expressed as an offset between the radiocarbon ages of samples from the two reservoirs at a single point in time. The marine reservoir effect (MRE) has been a major concern in the radiocarbon community, as it introduces an additional source of error that is often difficult to accurately quantify. For this reason, researchers are often reluctant to date marine material where they have another option. The influence of this phenomenon makes the study of the MRE important for a broad range of applications. The advent of Accelerator Mass Spectrometry (AMS) has reduced sample size requirements and increased measurement precision, in turn increasing the number of studies seeking to measure marine samples. These studies rely on overcoming the influence of the MRE on marine radiocarbon dates through the worldwide quantification of the local parameter ΔR, that is, the local variation from the global average MRE. Furthermore, the strong dependence on ocean dynamics makes the MRE a useful indicator for changes in oceanic circulation, carbon exchange between reservoirs, and the fate of atmospheric CO2, all of which impact Earth's climate. This article explores data from the Marine Reservoir Database and reviews the place of natural radiocarbon in oceanic records, focusing on key questions (e.g., changes in ocean dynamics) that have been answered by MRE studies and on their application to different subjects.

Atmosphere-ocean gas exchange based on radiocarbon data

NASA Astrophysics Data System (ADS)

Byalko, Alexey

2014-05-01

In recent decades, the intensity of global atmospheric convection has accelerated faster than climate warming; it is possible to judge this process from indirect data. Increasing ocean salinity contrasts provide evidence that evaporation has intensified [1]; sea surface wind velocities and wave heights have increased [2]. The CO2 gas exchange between the atmosphere and ocean must also simultaneously increase. Monthly measurements of atmospheric CO2 concentration have been published since 1958 [3], but directly measuring its fluxes from the atmosphere to the ocean and back is hardly possible. We show they can be reconstructed from 14C isotope concentration data. In the past century, two processes influenced the atmospheric 14C concentration in opposite directions: burning fossil fuels and testing nuclear weapons in the atmosphere. We compare the gas exchange theory with measurements of radiocarbon content in the atmosphere [4—6], which allows assessing the gas exchange quantitatively for the ocean to atmosphere and atmosphere to ocean fluxes separately for period 1960—2010 [7]. References 1. Durack P. J. and Wijffels S. E., J. Climate 23, 4342 (2010). 2. Young I. R., Sieger S., and Babanin A.V., Science 332, 451 (2011). 3. NOAA Earth System Research Laboratory Data: ftp://ftp.cmdl.noaa.gov/ccg/co2/trends/co2_mm_mlo.txt. 4. Nydal R., Lövseth K. // J. Geophys. Res. 1983. V. 88. P. 3579. 5. Levin I., Kromer B. // Radiocarbon. 1997. V. 39. P. 205. 6. Miller J.B., Lehman S.J., Montzka S.A., et al. // J. Geophys. Res. 2012. V. 117. D08302. 7. Byalko A.V. Doklady Physics, 2013. V. 58, 267-271.

Immunogenicity and safety of purified vero cell rabies vaccine (PVRV) produced by Liaoning Cheng Da Co. under Zagreb 2-1-1 or 5-dose Essen regimen in Chinese adults aged 50 and above.

PubMed

Wang, Jing; Luo, FengJi; Feng, ZiJian; Li, Li; Bai, YunHua; Ai, Xing; Ma, JianXin; Zhang, Zheng; Shi, NianMin

2017-01-02

Two kinds of regimens (2-1-1 and 1-1-1-1-1) can be selected after Zagreb regimen(2-1-1)of PVRV was officially approved in Beijing in January 2015. Up to now, the subjects for most studies about the comparison between Zagreb and Essen regimen are under 50 y old, rarely at and above. Aging of the immune system may result in decreasing efficacy of vaccination, especially for adults aged above 65-70 y. This study compared the safety and immunogenicity of the Zagreb and Essen regimen in Chinese adults aged 50 and above with the goal to provide a supplemental data for this age group. A total of 114 cases were divided into 2 groups randomly, received PVRV under the Zagreb and Essen regimens respectively. Serum samples were collected at D0, D7, D14, D42, D180 and D365 to determine the rabies serum neutralizing antibody by rapid fluorescent focus inhibition test (RFFIT). Safety analyses were made by comparing the AEs in day-3, day-7, and day-(7 + 21) in Zagreb or day-(7 + 28) in Essen by gender and age cohorts. 617 blood samples were obtained. Two groups showed similar immunogenicity, the neutralizing antibody titer of all subjects at D14 and D42 showed >0.5 IU/ml. Under the same regimen, Subjects ≥65 y had lower GMC than those who <65 years from D7 to D365 within 2 groups. This difference was significantly shown on D7, D14, D180 in Zagreb group, and on D180 in Essen group (t = 2.38, p = 0.02; t = 3.78, p < 0.001; t = 2.30, p = 0.03; t = 4.42, p < 0.001). Subjects<65 years had higher seroconversion rate compared to ≥65 y on D7, D180 and D365 in both 2 groups, this difference was also significantly shown on D180, D365 in Zagreb group and on D180 in Essen group (χ 2 = 20.66, p < 0.001; χ 2 = 6.56, p = 0.02; χ 2 = 10.96, p = 0.002). Two regimens all showed favorable performances with mildly or common adverse events (AEs). The incidence of local AEs after 3 d in Essen group was higher than Zagreb group (χ 2 = 9.69, p = 0.002). The most common local AE was pain

Immunogenicity and safety of purified vero cell rabies vaccine (PVRV) produced by Liaoning Cheng Da Co. under Zagreb 2-1-1 or 5-dose Essen regimen in Chinese adults aged 50 and above

PubMed Central

Wang, Jing; Luo, FengJi; Feng, ZiJian; Li, Li; Bai, YunHua; Ai, Xing; Ma, JianXin; Zhang, Zheng; Shi, NianMin

2017-01-01

ABSTRACT Background: Two kinds of regimens (2-1-1 and 1-1-1-1-1) can be selected after Zagreb regimen(2-1-1)of PVRV was officially approved in Beijing in January 2015. Up to now, the subjects for most studies about the comparison between Zagreb and Essen regimen are under 50 y old, rarely at and above. Aging of the immune system may result in decreasing efficacy of vaccination, especially for adults aged above 65–70 y. This study compared the safety and immunogenicity of the Zagreb and Essen regimen in Chinese adults aged 50 and above with the goal to provide a supplemental data for this age group. Methods: A total of 114 cases were divided into 2 groups randomly, received PVRV under the Zagreb and Essen regimens respectively. Serum samples were collected at D0, D7, D14, D42, D180 and D365 to determine the rabies serum neutralizing antibody by rapid fluorescent focus inhibition test (RFFIT). Safety analyses were made by comparing the AEs in day-3, day-7, and day-(7 + 21) in Zagreb or day-(7 + 28) in Essen by gender and age cohorts. Results: 617 blood samples were obtained. Two groups showed similar immunogenicity, the neutralizing antibody titer of all subjects at D14 and D42 showed >0.5 IU/ml. Under the same regimen, Subjects ≥65 y had lower GMC than those who <65 years from D7 to D365 within 2 groups. This difference was significantly shown on D7, D14, D180 in Zagreb group, and on D180 in Essen group (t = 2.38, p = 0.02; t = 3.78, p < 0.001; t = 2.30, p = 0.03; t = 4.42, p < 0.001). Subjects<65 years had higher seroconversion rate compared to ≥65 y on D7, D180 and D365 in both 2 groups, this difference was also significantly shown on D180, D365 in Zagreb group and on D180 in Essen group (χ2 = 20.66, p < 0.001; χ2 = 6.56, p = 0.02; χ2 = 10.96, p = 0.002). Two regimens all showed favorable performances with mildly or common adverse events (AEs). The incidence of local AEs after 3 d in Essen group was higher than Zagreb group (χ2 = 9.69, p = 0

Comparative AMS radiocarbon dating of pretreated versus non-pretreated tropical wood samples

NASA Astrophysics Data System (ADS)

Patrut, Adrian; von Reden, Karl F.; Lowy, Daniel A.; Mayne, Diana H.; Elder, Kathryn E.; Roberts, Mark L.; McNichol, Ann P.

2010-04-01

Several wood samples collected from Dorslandboom, a large iconic African baobab ( Adansonia digitata L.) from Namibia, were investigated by AMS radiocarbon dating subsequent to pretreatment and, alternatively, without pretreatment. The comparative statistical evaluation of results showed that there were no significant differences between fraction modern values and radiocarbon dates of the samples analyzed after pretreatment and without pretreatment, respectively. The radiocarbon date of the oldest sample was 993 ± 20 BP. Dating results also revealed that Dorslandboom is a multi-generation tree, with several stems showing different ages.

Mortar radiocarbon dating: preliminary accuracy evaluation of a novel methodology.

PubMed

Marzaioli, Fabio; Lubritto, Carmine; Nonni, Sara; Passariello, Isabella; Capano, Manuela; Terrasi, Filippo

2011-03-15

Mortars represent a class of building and art materials that are widespread at archeological sites from the Neolithic period on. After about 50 years of experimentation, the possibility to evaluate their absolute chronology by means of radiocarbon ((14)C) remains still uncertain. With the use of a simplified mortar production process in the laboratory environment, this study shows the overall feasibility of a novel physical pretreatment for the isolation of the atmospheric (14)CO(2) (i.e., binder) signal absorbed by the mortars during their setting. This methodology is based on the assumption that an ultrasonic attack in liquid phase isolates a suspension of binder carbonates from bulk mortars. Isotopic ((13)C and (14)C), % C, X-ray diffractometry (XRD), and scanning electron microscopy (SEM) analyses were performed to characterize the proposed methodology. The applied protocol allows suppression of the fossil carbon (C) contamination originating from the incomplete burning of the limestone during the quick lime production, providing unbiased dating for "laboratory" mortars produced operating at historically adopted burning temperatures.

Radiocarbon Analysis to Calculate New End-Member Values for Biomass Burning Source Samples Specific to the Bay Area

NASA Astrophysics Data System (ADS)

Yoon, S.; Kirchstetter, T.; Fairley, D.; Sheesley, R. J.; Tang, X.

2017-12-01

Elemental carbon (EC), also known as black carbon or soot, is an important particulate air pollutant that contributes to climate forcing through absorption of solar radiation and to adverse human health impacts through inhalation. Both fossil fuel combustion and biomass burning, via residential firewood burning, agricultural burning, wild fires, and controlled burns, are significant sources of EC. Our ability to successfully control ambient EC concentrations requires understanding the contribution of these different emission sources. Radiocarbon (14C) analysis has been increasingly used as an apportionment tool to distinguish between EC from fossil fuel and biomass combustion sources. However, there are uncertainties associated with this method including: 1) uncertainty associated with the isolation of EC to be used for radiocarbon analysis (e.g., inclusion of organic carbon, blank contamination, recovery of EC, etc.) 2) uncertainty associated with the radiocarbon signature of the end member. The objective of this research project is to utilize laboratory experiments to evaluate some of these uncertainties, particularly for EC sources that significantly impact the San Francisco Bay Area. Source samples of EC only and a mix of EC and organic carbon (OC) were produced for this study to represent known emission sources and to approximate the mixing of EC and OC that would be present in the atmosphere. These samples include a combination of methane flame soot, various wood smoke samples (i.e. cedar, oak, sugar pine, pine at various ages, etc.), meat cooking, and smoldering cellulose smoke. EC fractions were isolated using a Sunset Laboratory's thermal optical transmittance carbon analyzer. For 14C analysis, samples were sent to Woods Hole Oceanographic Institution for isotope analysis using an accelerated mass spectrometry. End member values and uncertainties for the EC isolation utilizing this method will be reported.

Annually resolved atmospheric radiocarbon records reconstructed from tree-rings

NASA Astrophysics Data System (ADS)

Wacker, Lukas; Bleicher, Niels; Büntgen, Ulf; Friedrich, Michael; Friedrich, Ronny; Diego Galván, Juan; Hajdas, Irka; Jull, Anthony John; Kromer, Bernd; Miyake, Fusa; Nievergelt, Daniel; Reinig, Frederick; Sookdeo, Adam; Synal, Hans-Arno; Tegel, Willy; Wesphal, Torsten

2017-04-01

The IntCal13 calibration curve is mainly based on data measured by decay counting with a resolution of 10 years. Thus high frequency changes like the 11-year solar cycles or cosmic ray events [1] are not visible, or at least not to their full extent. New accelerator mass spectrometry (AMS) systems today are capable of measuring at least as precisely as decay counters [2], with the advantage of using 1000 times less material. The low amount of material required enables more efficient sample preparation. Thus, an annually resolved re-measurement of the tree-ring based calibration curve can now be envisioned. We will demonstrate with several examples the multitude of benefits resulting from annually resolved radiocarbon records from tree-rings. They will not only allow for more precise radiocarbon dating but also contain valuable new astrophysical information. The examples shown will additionally indicate that it can be critical to compare AMS measurements with a calibration curve that is mainly based on decay counting. We often see small offsets between the two measurement techniques, while the reason is yet unknown. [1] Miyake F, Nagaya K, Masuda K, Nakamura T. 2012. A signature of cosmic-ray increase in AD 774-775 from tree rings in Japan. Nature 486(7402):240-2. [2] Wacker L, Bonani G, Friedrich M, Hajdas I, Kromer B, Nemec M, Ruff M, Suter M, Synal H-A, Vockenhuber C. 2010. MICADAS: Routine and high-precision radiocarbon dating. Radiocarbon 52(2):252-62.

Validation of a laboratory and hospital information system in a medical laboratory accredited according to ISO 15189.

PubMed

Biljak, Vanja Radisic; Ozvald, Ivan; Radeljak, Andrea; Majdenic, Kresimir; Lasic, Branka; Siftar, Zoran; Lovrencic, Marijana Vucic; Flegar-Mestric, Zlata

2012-01-01

The aim of the study was to present a protocol for laboratory information system (LIS) and hospital information system (HIS) validation at the Institute of Clinical Chemistry and Laboratory Medicine of the Merkur University Hospital, Zagreb, Croatia. Validity of data traceability was checked by entering all test requests for virtual patient into HIS/LIS and printing corresponding barcoded labels that provided laboratory analyzers with the information on requested tests. The original printouts of the test results from laboratory analyzer(s) were compared with the data obtained from LIS and entered into the provided template. Transfer of data from LIS to HIS was examined by requesting all tests in HIS and creating real data in a finding generated in LIS. Data obtained from LIS and HIS were entered into a corresponding template. The main outcome measure was the accuracy of transfer obtained from laboratory analyzers and results transferred from LIS and HIS expressed as percentage (%). The accuracy of data transfer from laboratory analyzers to LIS was 99.5% and of that from LIS to HIS 100%. We presented our established validation protocol for laboratory information system and demonstrated that a system meets its intended purpose.

[A refined institution was created: which serves to all of the members of insurance in the case of illness: foundation and development of Merkur's sanatorium in Zagreb until 1945].

PubMed

Fatović-Ferencić, Stella; Hofgräff, Darija

2013-01-01

The historiography of Zagreb sanatorium Merkur, founded by Merkur Insurance Society in 1930 is presented. The research is based on archival sources kept in the State's archives as well as in the National library in Zagreb aiming to identify the opening, building and governing the hospital until 1945. The analysis of the hospital historiography allowed the insight into social insurance development on our territory as well as of Zagreb's population receptivity towards the health institution and the quality of health service in the first half of the 20th century. The paper is dedicated to the 140th anniversary of Merkur Insurance Society foundation.

Youngest radiocarbon age for Jefferson's ground sloth, Megalonyx jeffersonii (Xenarthra, Megalonychidae)

NASA Astrophysics Data System (ADS)

Gregory McDonald, H.; Stafford, Thomas W.; Gnidovec, Dale M.

2015-03-01

A partial skeleton of the extinct ground sloth, Megalonyx jeffersonii, recovered from a farm near Millersburg, Ohio in 1890, was radiocarbon dated for the first time. The ungual dated is part of a skeleton mounted for exhibit at the Orton Geological Museum at Ohio State University and was the first mounted skeleton of this animal. From its initial discovery the bones were treated with multiple organic compounds that had the potential to compromise the radiocarbon age and the specimen required special treatments in order to obtain a valid radiocarbon age. The 14C measurement on the ungual from this skeleton (11,235 ± 40 14C yr BP = 13,180-13,034 cal yr BP) is the youngest 14C age presently determined for M. jeffersonii.

Biogenic contribution to PM-2.5 ambient aerosol from radiocarbon measurements

NASA Astrophysics Data System (ADS)

Lewis, C.; Klouda, G.; Ellenson, W.

2003-04-01

Knowledge of the relative contributions of biogenic versus anthropogenic sources to ambient aerosol is of great interest in the formulation of strategies to achieve nationally mandated air quality standards. Radiocarbon (14C) measurements provide a means to quantify the biogenic fraction of any carbon-containing sample of ambient aerosol. In the absence of an impact from biomass burning (e.g., during summertime) such measurements can provide an estimate of the contribution of biogenic secondary organic aerosol, from biogenic volatile organic compound precursors. Radiocarbon results for 11.5-h PM-2.5 samples collected near Nashville, Tennessee, USA, during summer 1999 will be presented. On average the measured biogenic fraction was surprisingly large (more than half), with the average biogenic fraction for night samples being only slightly smaller than for day samples. Discussion will include (a) description of the radiocarbon methodology, (b) use of radiocarbon measurements on local vegetation and fuel samples as calibration data, (c) concurrent measurements of organic carbon and elemental carbon ambient concentrations, (d) assessment of organic aerosol sampling artifact through use of organic vapor denuders, variable face velocities, and filter extraction, and (e) comparison with published radiocarbon results obtained in Houston, Texas in a similar study. Disclaimer: This work has been funded wholly or in part by the United States Environmental Protection Agency under Interagency Agreement No. 13937923 to the National Institute of Standards and Technology, and Contract No. 68-D5-0049 to ManTech Environmental Tecnology, Inc. It has been subjected to Agency review and approved for publication.

Ambulatory oral surgery: 1-year experience with 11680 patients from Zagreb district, Croatia.

PubMed

Jokić, Dražen; Macan, Darko; Perić, Berislav; Tadić, Marinka; Biočić, Josip; Đanić, Petar; Brajdić, Davor

2013-02-01

To examine the types and frequencies of oral surgery diagnoses and ambulatory oral surgical treatments during one year period at the Department of Oral Surgery, University Hospital Dubrava in Zagreb, Croatia. Sociodemographic and clinical data on 11680 ambulatory patients, treated between January 1 and of December 31, 2011 were retrieved from the hospital database using a specific protocol. The obtained data were subsequently analyzed in order to assess the frequency of diagnoses and differences in sex and age. The most common ambulatory procedure was tooth extraction (37.67%) and the most common procedure in ambulatory operating room was alveolectomy (57.25%). The test of proportions showed that significantly more extractions (P<0.001) and intraoral incisions (P<0.001) were performed among male patients, whereas significantly more alveolectomies and apicoectomies were performed among female patients (P<0.001). A greater prevalence of periodontal disease was found in patients residing in Zagreb than in patients residing in rural areas. The data from this study may be useful for planning of ambulatory oral surgery services, budgeting, and sustaining quality improvement, enhancing oral surgical curricula, training and education of primary health care doctors and oral surgery specialists, and promoting patients' awareness of the importance of oral health.

Concordance of Collagen-Based Radiocarbon and Aspartic-Acid Racemization Ages

PubMed Central

Bada, Jeffrey L.; Schroeder, Roy A.; Protsch, Reiner; Berger, Rainer

1974-01-01

By determining the extent of racemization of aspartic acid in a well-dated bone, it is possible to calculate the in situ first-order rate constant for the interconversion of the L and D enantiomers of aspartic acid. Collagen-based radiocarbon-dated bones are shown to be suitable samples for use in “calibrating” the racemization reaction. Once the aspartic-acid racemization reaction has been “calibrated” for a site, the reaction can be used to date other bones from the deposit. Ages deduced by this method are in good agreement with radiocarbon ages. These results provide evidence that the aspartic-acid racemization reaction is an important chronological tool for dating bones either too old or too small for radiocarbon dating. As an example of the potential application of the technique for dating fossil man, a piece of Rhodesian Man from Broken Hill, Zambia, was analyzed and tentatively assigned an age of about 110,000 years. PMID:4522802

New Radiocarbon Dates on Upper Mid-West Proboscideans: Determining Date Robustness

NASA Astrophysics Data System (ADS)

Hodgins, G.; Widga, C.; Lengyel, S. N.; Saunders, J.; Walker, J. D.

2013-12-01

With the objective of refining the picture of Megafaunal extinction patterns in the upper Midwest in the terminal Pleistocene, we have assembled for radiocarbon dating specimens from more than 80 distinct Mammut and Mammuthus remains from potentially late sites. So far, we have measurements for 65 bones, tusks and teeth, nearly double the extant number of published dates . These new specimens were all from museums rather than excavation sites, and 60% were known to be coated with a consolidant. The predominant consolidant was Butvar B-76, however shellac, Elmer's Glue, Glyptol were also noted in the conservation records, or deduced from knowledge of a particular museum's practices. Given the objective of the project is to identify extinction patterns, coupled with the wide prevalence of consolidants amongst the specimen set, it was imperative that testing be carried out to confirm that radiocarbon laboratory protocols removed the consolidants, so that ultimately the dates can be considered robust. To this end, key specimens were dated three times using different sample preparation protocols. These were 1) a solvent extraction followed by a modified Longin-plus -Base continuous flow collagen extraction method used in the NSF-Arizona AMS facility, 2) the solvent/modified Longin method plus ultrafiltration, and 3) solvent/modified Longin method plus hydroxyproline single amino acid dating. Among the specimens subjected to triplicate testing were some of the youngest late Wisconsin proboscidean specimens from the Upper Midwest Region. The data reveal general agreement between the different protocols, and suggested either limited penetration of consolidants into the specimens, or that the standard laboratory cleaning protocols were sufficient to remove traces from deep within bone, tooth or tusk tissue. The preservation of each specimen, recorded in terms of collagen content, C/N ratio and stable isotope values, indicated that most were actually well preserved, implying

Analysis of Users' Searches of CD-ROM Databases in the National and University Library in Zagreb.

ERIC Educational Resources Information Center

Jokic, Maja

1997-01-01

Investigates the search behavior of CD-ROM database users in Zagreb (Croatia) libraries: one group needed a minimum of technical assistance, and the other was completely independent. Highlights include the use of questionnaires and transaction log analysis and the need for end-user education. The questionnaire and definitions of search process…

Comparison of Soil Organic Matter Dynamics at Four Temperate Deciduous Forests with Physical Fractionation and Radiocarbon Measurements

NASA Astrophysics Data System (ADS)

McFarlane, K. J.; Torn, M. S.; Hanson, P. J.; Swanston, C.; Guilderson, T. P.; Porras, R. C.

2009-12-01

very little C recovered in the occluded light fraction. Radiocarbon-based SOM turnover times for the sites suggest that soil carbon pools in all three fractions turn over much more quickly at MOZ, the warmest site, than at the other sites. In addition, turnover times for free and occluded light fractions were slower at UMBS and BEF, the coolest sites, than at HAF and MOZ. These results suggest that soil type and climate interact to control soil organic matter cycling. Specifically, soil organic matter decomposition is slower in cooler than in warmer climates and there is more physically protected C in soils of finer texture, at least at the scale encompassed by our study. Acknowledgments This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and by Lawrence Berkeley National Laboratory under Contract DE-AC02-05CH11231.

A complete terrestrial radiocarbon record for 11.2 to 52.8 kyr B.P.

PubMed

Bronk Ramsey, Christopher; Staff, Richard A; Bryant, Charlotte L; Brock, Fiona; Kitagawa, Hiroyuki; van der Plicht, Johannes; Schlolaut, Gordon; Marshall, Michael H; Brauer, Achim; Lamb, Henry F; Payne, Rebecca L; Tarasov, Pavel E; Haraguchi, Tsuyoshi; Gotanda, Katsuya; Yonenobu, Hitoshi; Yokoyama, Yusuke; Tada, Ryuji; Nakagawa, Takeshi

2012-10-19

Radiocarbon ((14)C) provides a way to date material that contains carbon with an age up to ~50,000 years and is also an important tracer of the global carbon cycle. However, the lack of a comprehensive record reflecting atmospheric (14)C prior to 12.5 thousand years before the present (kyr B.P.) has limited the application of radiocarbon dating of samples from the Last Glacial period. Here, we report (14)C results from Lake Suigetsu, Japan (35°35'N, 135°53'E), which provide a comprehensive record of terrestrial radiocarbon to the present limit of the (14)C method. The time scale we present in this work allows direct comparison of Lake Suigetsu paleoclimatic data with other terrestrial climatic records and gives information on the connection between global atmospheric and regional marine radiocarbon levels.

Radiocarbon dating of plant macrofossils from tidal-marsh sediment

USGS Publications Warehouse

Kemp, A.C.; Nelson, Alan R.; Horton, B.P.

2013-01-01

Tidal-marsh sediment is an archive of Holocene environmental changes, including movements of sea and land levels, and extreme events such as hurricanes, earthquakes, and tsunamis. Accurate and precise radiocarbon dating of environmental changes is necessary to estimate rates of change and the recurrence interval (frequency) of events. Plant macrofossils preserved in growth position (or deposited soon after death) in tidal-marsh sediment are ideal samples for dating such changes. In this chapter, we focus on the selection of plant macrofossils for radiocarbon dating and the application of ages from different types of macrofossils to varied research projects, and make recommendations for selection and preparation of tidal-marsh samples for dating.

Validation of a laboratory and hospital information system in a medical laboratory accredited according to ISO 15189

PubMed Central

Biljak, Vanja Radisic; Ozvald, Ivan; Radeljak, Andrea; Majdenic, Kresimir; Lasic, Branka; Siftar, Zoran; Lovrencic, Marijana Vucic; Flegar-Mestric, Zlata

2012-01-01

Introduction The aim of the study was to present a protocol for laboratory information system (LIS) and hospital information system (HIS) validation at the Institute of Clinical Chemistry and Laboratory Medicine of the Merkur University Hospital, Zagreb, Croatia. Materials and methods: Validity of data traceability was checked by entering all test requests for virtual patient into HIS/LIS and printing corresponding barcoded labels that provided laboratory analyzers with the information on requested tests. The original printouts of the test results from laboratory analyzer(s) were compared with the data obtained from LIS and entered into the provided template. Transfer of data from LIS to HIS was examined by requesting all tests in HIS and creating real data in a finding generated in LIS. Data obtained from LIS and HIS were entered into a corresponding template. The main outcome measure was the accuracy of transfer obtained from laboratory analyzers and results transferred from LIS and HIS expressed as percentage (%). Results: The accuracy of data transfer from laboratory analyzers to LIS was 99.5% and of that from LIS to HIS 100%. Conclusion: We presented our established validation protocol for laboratory information system and demonstrated that a system meets its intended purpose. PMID:22384522

Measuring Carbon-based Contaminant Mineralization Using Combined CO2 Flux and Radiocarbon Analyses.

PubMed

Boyd, Thomas J; Montgomery, Michael T; Cuenca, Richard H; Hagimoto, Yutaka

2016-10-21

A method is described which uses the absence of radiocarbon in industrial chemicals and fuels made from petroleum feedstocks which frequently contaminate the environment. This radiocarbon signal - or rather the absence of signal - is evenly distributed throughout a contaminant source pool (unlike an added tracer) and is not impacted by biological, chemical or physical processes (e.g., the 14 C radioactive decay rate is immutable). If the fossil-derived contaminant is fully degraded to CO2, a harmless end-product, that CO2 will contain no radiocarbon. CO2 derived from natural organic matter (NOM) degradation will reflect the NOM radiocarbon content (usually <30,000 years old). Given a known radiocarbon content for NOM (a site background), a two end-member mixing model can be used to determine the CO2 derived from a fossil source in a given soil gas or groundwater sample. Coupling the percent CO2 derived from the contaminant with the CO2 respiration rate provides an estimate for the total amount of contaminant degraded per unit time. Finally, determining a zone of influence (ZOI) representing the volume from which site CO2 is collected allows determining the contaminant degradation per unit time and volume. Along with estimates for total contaminant mass, this can ultimately be used to calculate time-to-remediate or otherwise used by site managers for decision-making.

Measuring Carbon-based Contaminant Mineralization Using Combined CO2 Flux and Radiocarbon Analyses

PubMed Central

Boyd, Thomas J.; Montgomery, Michael T.; Cuenca, Richard H.; Hagimoto, Yutaka

2016-01-01

A method is described which uses the absence of radiocarbon in industrial chemicals and fuels made from petroleum feedstocks which frequently contaminate the environment. This radiocarbon signal — or rather the absence of signal — is evenly distributed throughout a contaminant source pool (unlike an added tracer) and is not impacted by biological, chemical or physical processes (e.g., the 14C radioactive decay rate is immutable). If the fossil-derived contaminant is fully degraded to CO2, a harmless end-product, that CO2 will contain no radiocarbon. CO2 derived from natural organic matter (NOM) degradation will reflect the NOM radiocarbon content (usually <30,000 years old). Given a known radiocarbon content for NOM (a site background), a two end-member mixing model can be used to determine the CO2 derived from a fossil source in a given soil gas or groundwater sample. Coupling the percent CO2 derived from the contaminant with the CO2 respiration rate provides an estimate for the total amount of contaminant degraded per unit time. Finally, determining a zone of influence (ZOI) representing the volume from which site CO2 is collected allows determining the contaminant degradation per unit time and volume. Along with estimates for total contaminant mass, this can ultimately be used to calculate time-to-remediate or otherwise used by site managers for decision-making. PMID:27805601

Vulcanism and Radiocarbon Dates

DOE R&D Accomplishments Database

Libby, L. M.; Libby, W. F.

1972-10-01

We consider whether the long term perturbation of radiocarbon dates, which is known to be approximately a sin function of period about 8000 years and amplitude of about 8% peak-to-peak, could have been caused in any major part by vulcanism. We conclude that this is not the case. On the contrary, present day volcanoes are a far less important source of inert CO{sub 2} (about 100 fold less) than is man's burning of fossil fuels which has caused the Suess dilution of about 2%. (auth)

Heavy metals and metalloid content in vegetables and soil collected from the gardens of Zagreb, Croatia.

PubMed

Puntarić, Dinko; Vidosavljević, Domagoj; Gvozdić, Vlatka; Puntarić, Eda; Puntarić, Ida; Mayer, Dijana; Bosnir, Jasna; Lasić, Dario; Jergović, Matijana; Klarić, Ivana; Vidosavljević, Marina; Krivdić, Ivancica

2013-09-01

Aim of this study was to determine concentration of Pb, Cd, As and Hg in green leafy vegetables and soil in the urban area of Zagreb, Croatia and to determine if there is a connection between the contamination of soil and vegetables. Green leafy vegetables and soil samples were taken from the gardens located in the outskirts of the city. Concentrations of Pb, Cd, As and Hg were determined by atomic absorption spectrometry; showing that average concentrations of metals and metalloids in vegetables and in soil, regardless of the location of sampling were below the maximum allowed concentration (MAC). The analysis determined that metal concentrations in only nine vegetable samples (9%) were above maximum allowed values prescribed by national and European legislation (three with higher concentrations of Pb, one with a higher concentration of Cd and five with higher concentrations of Hg). Concentrations of contaminants present in the analysed samples, in general, are lower than the ones published in similar studies. The final distribution and concentration of contaminants in vegetables of Zagreb, besides industry and traffic, is affected by the dominant wind direction.

Year of birth determination using radiocarbon dating of dental enamel

PubMed Central

Buchholz, B.A.; Spalding, K.L

2010-01-01

Radiocarbon dating is typically an archaeological tool rather than a forensic one. Recently however, we have shown that the amount of radiocarbon present in tooth enamel, as a result of nuclear bomb testing during the cold war, is a remarkably accurate indicator of when a person is born. Enamel isolated from human teeth is processed to form graphite and carbon-14 (14C) levels are measured using accelerator mass spectrometry. Since there is no turnover of enamel after it is formed, 14C levels in the enamel represent 14C levels in the atmosphere at the time of its formation. In this paper we describe the strategy used to determine the date of birth of an individual based on radiocarbon levels in tooth enamel, focusing on the methodology of this strategy. Year of birth information can significantly assist police investigators when the identity of a deceased individual is unknown. In such cases police will try to match particulars of the unidentified individual (which is often only gender and/or an estimate of age), with particulars from missing persons lists. PMID:20976120

Agriculture, population growth, and statistical analysis of the radiocarbon record.

PubMed

Zahid, H Jabran; Robinson, Erick; Kelly, Robert L

2016-01-26

The human population has grown significantly since the onset of the Holocene about 12,000 y ago. Despite decades of research, the factors determining prehistoric population growth remain uncertain. Here, we examine measurements of the rate of growth of the prehistoric human population based on statistical analysis of the radiocarbon record. We find that, during most of the Holocene, human populations worldwide grew at a long-term annual rate of 0.04%. Statistical analysis of the radiocarbon record shows that transitioning farming societies experienced the same rate of growth as contemporaneous foraging societies. The same rate of growth measured for populations dwelling in a range of environments and practicing a variety of subsistence strategies suggests that the global climate and/or endogenous biological factors, not adaptability to local environment or subsistence practices, regulated the long-term growth of the human population during most of the Holocene. Our results demonstrate that statistical analyses of large ensembles of radiocarbon dates are robust and valuable for quantitatively investigating the demography of prehistoric human populations worldwide.

Year of birth determination using radiocarbon dating of dental enamel.

PubMed

Buchholz, B A; Spalding, K L

2010-05-01

Radiocarbon dating is typically an archaeological tool rather than a forensic one. Recently however, we have shown that the amount of radiocarbon present in tooth enamel, as a result of nuclear bomb testing during the cold war, is a remarkably accurate indicator of when a person is born. Enamel isolated from human teeth is processed to form graphite and carbon-14 ((14)C) levels are measured using accelerator mass spectrometry. Since there is no turnover of enamel after it is formed, (14)C levels in the enamel represent (14)C levels in the atmosphere at the time of its formation. In this paper we describe the strategy used to determine the date of birth of an individual based on radiocarbon levels in tooth enamel, focusing on the methodology of this strategy. Year of birth information can significantly assist police investigators when the identity of a deceased individual is unknown. In such cases police will try to match particulars of the unidentified individual (which is often only gender and/or an estimate of age), with particulars from missing persons lists.

Constraining the Stratosphere-Troposphere Exchange of Radiocarbon using AirCore 14CO2 Measurements

NASA Astrophysics Data System (ADS)

Chen, H.

2016-12-01

Radiocarbon (14C) plays an important role in the carbon cycle studies to understand both natural and anthropogenic carbon fluxes, but also in atmospheric chemistry to constrain hydroxyl radical (OH) concentrations in the atmosphere. Apart from the enormous 14C emissions from nuclear bomb testing in the 1950s and 1960s, radiocarbon is primarily produced in the upper atmosphere due to reactions of nitrogen nuclei with thermal neutrons that are induced by cosmic rays. 14C is quickly oxidized to 14CO, which is then further oxidized to 14CO2 by OH. To this end, better understanding the radiocarbon source is very useful to advance the use of radiocarbon for these applications. However, upper atmospheric 14C observations have been very sparse to constrain the magnitude and the location of the 14C production as well as the transport of radiocarbon from the stratosphere to the troposphere. Recently we have successfully made stratospheric 14CO2 measurements using AirCore samples from Sodankylä, Northern Finland, along with regular AirCore profiles of CO2, CH4, and CO since 2013. In this study, we calculate the stratosphere-troposphere exchange of 14C using the correlation between 14CO2 and N2O, and the estimated N2O loss rate. Besides this, we assess the impact of the mean age of air on 14CO2 profiles. Furthermore, we will evaluate the influence of different cosmogenic 14C production scenarios and the uncertainties in the OH field on the seasonal cycles of radiocarbon and on the stratosphere-troposphere exchange.

Some cosmic radiation dose measurements aboard flights connecting Zagreb Airport.

PubMed

Vuković, B; Radolić, V; Lisjak, I; Vekić, B; Poje, M; Planinić, J

2008-02-01

When primary particles from space, mainly protons, enter the atmosphere, they produce interactions with air nuclei, and cosmic-ray showers are induced. The radiation field at aircraft altitude is complex, with different types of particles, mainly photons, electrons, positrons and neutrons, with a large energy range. The non-neutron component of cosmic radiation dose aboard A320 and ATR40 aircraft was measured with TLD-100 (LiF:Mg,Ti) detectors and the Mini 6100 semiconductor dosimeter; the neutron dose was measured with the neutron dosimeter consisted of LR-115 track detector and boron foil BN-1 or 10B converter. The estimated occupational effective dose for the aircraft crew (A320) working 500 h per year was 1.64 mSv. Another experiment was performed at the flights Zagreb-Paris-Buenos Aires and reversely, when one measured non-neutron cosmic radiation dose; for 26.7 h of flight, the MINI 6100 dosimeter gave an average dose rate of 2.3 microSv/h and the TLD dosimeter registered the dose equivalent of 75 microSv or the average dose rate of 2.7 microSv/h; the neutron dosimeter gave the dose rate of 2.4 microSv/h. In the same month, February 2005, a traveling to Japan (24-h-flight: Zagreb-Frankfurt-Tokyo and reversely) and the TLD-100 measurement showed the average dose rate of 2.4microSv/h; the neutron dosimeter gave the dose rate of 2.5 microSv/h. Comparing dose rates of the non-neutron component (low LET) and the neutron one (high LET) of the radiation field at the aircraft flight level, we could conclude that the neutron component carried about 50% of the total dose, that was near other known data.

Holocene age of the Yuha burial: Direct radiocarbon determinations by accelerator mass spectrometry

USGS Publications Warehouse

Stafford, Thomas W.; Jull, A.J.T.; Zabel, T.H.; Donahue, D.J.; Duhamel, R.C.; Brendel, K.; Haynes, C.V.; Bischoff, J.L.; Payen, L.A.; Taylor, R.E.

1984-01-01

The view that human populations may not have arrived in the Western Hemisphere before about 12,000 radiocarbon yr BP1,2 has been challenged by claims of much greater antiquity for a small number of archaeological sites and human skeleton samples. One such site is the Homo sapiens sapiens cairn burial excavated in 1971 from the Yuha desert, Imperial County, California3-5. Radiocarbon analysis of caliche coating one of the bones of the skeleton yielded a radiocarbon age of 21,500??1,000 yr BP4, while radiocarbon and uranium series analyses of caliche coating a cairn boulder yielded ages of 22,125??400 and 19,000??3,000 yr BP, respectively5. The late Pleistocene age assignment to the Yuha burial has been challenged by comparing the cultural context of the burial with other cairn burials in the same region6, on the basis of the site's geomorphological context and from radiocarbon analyses of soil caliches. 7,8 In rebuttal, arguments in defence of the original age assignment have been presented9,10 as well as an amino acid racemization analysis on the Yuha skeleton indicating an age of 23,600??2,600 yr BP11. The tandem accelerator mass spectrometer at the University of Arizona has now been used to measure the ratio of 14C/13C in several organic and inorganic fractions of post-cranial bone from the Yuha H. sapiens sapiens skeleton. Isotope ratios from six chemical fractions all yielded radiocarbon ages for the skeleton of less than 4,000 yr BP. These results indicate that the Yuha skeleton is of Holocene age, in agreement with the cultural context of the burial, and in disagreement with the previously assigned Pleistocene age of 19,000-23,000 yr. ?? 1984 Nature Publishing Group.

New radiocarbon ages from cirques in Colorado Front Range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, P.T.; Birkeland, P.W.; Caine, N.

The authors recovered sediment cores 3.1 m long from Blue Lake ([approximately]37m water depth, [approximately]3,445m a.s.l., 40[degree]5 minutes 20 seconds N, 105[degree]37 minutes 08 seconds W) and 2.7m long from Lake Dorothy ([approximately]35m water depth, [approximately]3,675m a.s.l., 40[degree]00 minutes 46 seconds N, 105[degree]41 minutes 11 seconds W). A light-weight percussion coring system suspended from perlon ropes was used because of sediment thicknesses, water depths, and ski-backpacking requirements. Lake ice provided a stable coring platform. One purpose of the project is provision of a high-resolution record of environmental change in the subalpine/alpine ecotone during the Holocene, under the auspices of themore » Niwot Ridge Long-Term Ecological Research program. The sediment cores also provide minimum-limiting radiocarbon ages for deglaciation of cirques and the deposits that impound their tarns. Here the authors report on this second purpose. The Blue Lake core bottomed in sandy, gray, inorganic sediment, presumably glacial diamict. A bulk sample from 2.8--2.9m depth yielded a conventional radiocarbon age of 12,275[+-]345 yrs BP. Thus, ice retreated from the site by 12 ka. Since 12 ka both glacial and rock-glacial sediments have been deposited upvalley; some of these events may be recognized in the core. In contrast, the Lake Dorothy core did not penetrate gray inorganic diamict and is entirely organic-rich. A bulk sample from 2.65--2.7m depth yielded a conventional radiocarbon age of 10,910 [+-] 320 yrs BP. Thus, the moraines impounding the lake are 2--3 times older than suggested by a combination of relative-age methods and one radiocarbon age from surface sediments.« less

A study on utilization of oral contraceptives in the City of Zagreb (2008-2010).

PubMed

Zelić-Kerep, Ana; Stimac, Danijela; Ozić, Sanja; Zivković, Kresimir; Zivković, Nikica

2014-06-01

Main aim of this study is to quantify and analyze the utilization and utilization trends of oral hormonal contraceptives in the City of Zagreb, 2008-2010, and to propose potential interventions, if necessary. Data gathered from Zagreb pharmacies were assessed by Anatomical Therapeutic Chemical Classification of drugs and Daily Defined Dose methodology. An alarming decrease in total utilization of hormonal contraceptives by 76% from 2008-2009 was found as the main result of this study. A major decrease by 95.5% in utilization of G03AB04 subgroup, sequential combined oral contraceptives, was noted in the year 2009. The subgroup G03AC0, progesterone-only pill group, showed a stable trend, and it became the most utilized subgroup in 2010, due to the decrease in utilization of both fixed and sequential combined oral contraceptives. Utilization of oral contraceptives in Croatia is not regulated adequately, since such dynamics in utilization can occur unnoticed. Measures need to take place in order to improve this situation. Proposed measures include organized farmacovigilance, prescription based on guidelines, and strict screening for risk factors in women seeking oral contraception. More research is required in Croatia to understand the pattern of utilization of hormonal contraceptives and to find the true cause of decrease in utilization of oral contraceptives.

The radiocarbon reservoir age of the Chukchi Sea, Arctic Ocean

NASA Astrophysics Data System (ADS)

Pearce, C.; Gyllencreutz, R.; West, G.; O'Regan, M.; Jakobsson, M.

2017-12-01

Radiocarbon (14C) dating is the standard method for obtaining the age of marine sediments of Holocene and late Pleistocene age. For accurate calibrations, however, this tool relies on precise knowledge of the local radiocarbon reservoir age of the surface ocean, i.e. the regional difference (ΔR) from the average global marine calibration dataset. This parameter has become impossible to measure from modern mollusk samples because of 14C contamination from extensive testing of thermo-nuclear bombs in the second half of the twentieth century. The local reservoir age can thus only be calculated from the radiocarbon age of samples collected before AD 1950 or from sediment records containing absolute age markers, derived from e.g. tephrochronology or paleomagnetism. Knowledge of the marine reservoir age in the Arctic Ocean is extremely sparse, and relies on work by only a few studies. No information exists for the entire East Siberian Sea, and the Chukchi Sea is represented solely by sites along the Alaskan coast. Here we present new radiocarbon measurements on historical mollusk collections from the East Siberian and Chukchi margins. Our results show a clear and consistent signal of "old" Pacific Water in the Chukchi Sea with ΔR values around 450 years. Towards the East Siberian Sea the values drop as Pacific Water has decreased influence further away from the Bering Strait. Complementing the modern data, we also provide constraints on the reservoir age during the late Holocene. These are based on tephrochronology and high resolution analyses of paleomagnetic secular variation from a sediment archive from Herald Canyon, Chukchi Sea.

Marine radiocarbon reservoir age simulations for the past 50,000 years

NASA Astrophysics Data System (ADS)

Butzin, M.; Köhler, P.; Lohmann, G.

2017-08-01

Radiocarbon (14C) dating calibration for the last glacial period largely relies on cross-dated marine 14C records. However, marine reservoirs are isotopically depleted with respect to the atmosphere and therefore have to be corrected by the Marine Radiocarbon Ages of surface waters (MRAs), whose temporal variabilities are largely unknown. Here we present simulations of the spatial and temporal variability in MRAs using a three-dimensional ocean circulation model covering the past 50,000 years. Our simulations are compared to reconstructions of past surface ocean Δ14C. Running the model with different climatic boundary conditions, we find that low-latitude to midlatitude MRAs have varied between 400 and 1200 14C years, with values of about 780 14C years at the Last Glacial Maximum. Reservoir ages exceeding 2000 14C years are simulated in the polar oceans. Our simulation results can be used as first-order approximation of the MRA variability in future radiocarbon calibration efforts.

Radiocarbon and stable isotopes in Palmyra corals during the past century

NASA Astrophysics Data System (ADS)

Druffel-Rodriguez, Kevin C.; Vetter, Desiree; Griffin, Sheila; Druffel, Ellen R. M.; Dunbar, Robert B.; Mucciarone, David A.; Ziolkowski, Lori A.; Sanchez-Cabeza, Joan-Albert

2012-04-01

Annual samples from two Palmyra Atoll corals (Porites lutea) that lived during the past 110 years were analyzed for radiocarbon (Δ14C) and δ18O. The Δ14C values decreased 7.6‰ from 1896 to 1953, similar to other coral records from the tropical and subtropical Pacific. Δ14C values rose from ˜-60‰ to ˜+110‰ by 1980 due to the input of bomb radiocarbon from the atmosphere. Elevated Δ14C values were observed for the mid- to late-1950s, suggesting early input of bomb radiocarbon, possibly from the largest Marshall Islands bomb tests in 1954. Secondary aragonite precipitation was identified in a portion of one core using scanning electron microscopy and X-radiography, and was responsible for high δ18O and δ13C values and a correlation between them. The Δ14C results were more resistant to alteration, except when contamination was from the bomb era (>1956).

Poles of the Zagreb analysis partial-wave T matrices

NASA Astrophysics Data System (ADS)

Batinić, M.; Ceci, S.; Švarc, A.; Zauner, B.

2010-09-01

The Zagreb analysis partial-wave T matrices included in the Review of Particle Physics [by the Particle Data Group (PDG)] contain Breit-Wigner parameters only. As the advantages of pole over Breit-Wigner parameters in quantifying scattering matrix resonant states are becoming indisputable, we supplement the original solution with the pole parameters. Because of an already reported numeric error in the S11 analytic continuation [Batinić , Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.57.1004 57, 1004(E) (1997); arXiv:nucl-th/9703023], we declare the old BATINIC 95 solution, presently included by the PDG, invalid. Instead, we offer two new solutions: (A) corrected BATINIC 95 and (B) a new solution with an improved S11 πN elastic input. We endorse solution (B).

Age estimation in forensic sciences: application of combined aspartic acid racemization and radiocarbon analysis.

PubMed

Alkass, Kanar; Buchholz, Bruce A; Ohtani, Susumu; Yamamoto, Toshiharu; Druid, Henrik; Spalding, Kirsty L

2010-05-01

Age determination of unknown human bodies is important in the setting of a crime investigation or a mass disaster because the age at death, birth date, and year of death as well as gender can guide investigators to the correct identity among a large number of possible matches. Traditional morphological methods used by anthropologists to determine age are often imprecise, whereas chemical analysis of tooth dentin, such as aspartic acid racemization, has shown reproducible and more precise results. In this study, we analyzed teeth from Swedish individuals using both aspartic acid racemization and radiocarbon methodologies. The rationale behind using radiocarbon analysis is that aboveground testing of nuclear weapons during the cold war (1955-1963) caused an extreme increase in global levels of carbon-14 ((14)C), which has been carefully recorded over time. Forty-four teeth from 41 individuals were analyzed using aspartic acid racemization analysis of tooth crown dentin or radiocarbon analysis of enamel, and 10 of these were split and subjected to both radiocarbon and racemization analysis. Combined analysis showed that the two methods correlated well (R(2) = 0.66, p < 0.05). Radiocarbon analysis showed an excellent precision with an overall absolute error of 1.0 +/- 0.6 years. Aspartic acid racemization also showed a good precision with an overall absolute error of 5.4 +/- 4.2 years. Whereas radiocarbon analysis gives an estimated year of birth, racemization analysis indicates the chronological age of the individual at the time of death. We show how these methods in combination can also assist in the estimation of date of death of an unidentified victim. This strategy can be of significant assistance in forensic casework involving dead victim identification.

The knowledge and understanding of preanalytical phase among biomedicine students at the University of Zagreb.

PubMed

Dukic, Lora; Jokic, Anja; Kules, Josipa; Pasalic, Daria

2016-01-01

The educational program for health care personnel is important for reducing preanalytical errors and improving quality of laboratory test results. The aim of our study was to assess the level of knowledge on preanalytical phase in population of biomedicine students through a cross-sectional survey. A survey was sent to students on penultimate and final year of Faculty of Pharmacy and Biochemistry--study of medical biochemistry (FPB), Faculty of Veterinary Medicine (FVM) and School of Medicine (SM), University of Zagreb, Croatia, using the web tool SurveyMonkey. Survey was composed of demographics and 14 statements regarding the preanalytical phase of laboratory testing. Comparison of frequencies and proportions of correct answers was done with Fisher's exact test and test of comparison of proportions, respectively. Study included 135 participants, median age 24 (23-40) years. Students from FPB had higher proportion of correct answers (86%) compared to students from other biomedical faculties 62%, P < 0.001. Students from FPB were more conscious of the importance of specimen mixing (P = 0.027), prevalence of preanalytical errors (P = 0.001), impact of hemolysis (P = 0.032) and lipemia interferences (P = 0.010), proper choice of anticoagulants (P = 0.001), transport conditions for ammonia sample (P < 0.001) and order of draw during blood specimen collection (P < 0.001), in comparison with students from SM and FVM. Students from FPB are more conscious of the importance of preanalytical phase of testing in comparison with their colleagues from other biomedical faculties. No difference in knowledge between penultimate and final year of the same faculty was found.

Year of Birth Determination Using Radiocarbon Dating of Dental Enamel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buchholz, B A; Spalding, K L

2009-03-10

Radiocarbon dating is typically an archaeological tool rather than a forensic one. Recently however, we have shown that the amount of radiocarbon present in tooth enamel, as a result of nuclear bomb testing during the cold war, is a remarkably accurate indicator of when a person is born. Enamel isolated from human teeth is processed to form graphite and carbon-14 ({sup 14}C) levels are measured using accelerator mass spectrometry. Since there is no turnover of enamel after it is formed, {sup 14}C levels in the enamel represent {sup 14}C levels in the atmosphere at the time of its formation. Inmore » this paper we describe the strategy used to determine the date of birth of an individual based on radiocarbon levels in tooth enamel, focusing on the methodology of this strategy. Year of birth information can significantly assist police investigators when the identity of a deceased individual is unknown. In such cases police will try to match particulars of the unidentified individual (which is often only gender and/or an estimate of age), with particulars from missing persons lists.« less

The Holocene Minimum of the West Antarctic Ice Sheet: Radiocarbon Model Ages for Subglacial Sediments

NASA Astrophysics Data System (ADS)

Tulaczyk, S. M.; Stansell, N.; Scherer, R. P.; Powell, R. D.

2017-12-01

It is commonly assumed that the West Antarctic Ice Sheet (WAIS) is at the present time as small as it has been since at least the last interglacial period about 125,000 years ago. Yet, our recent analyses of subglacial sediments recovered from beneath the ice sheet indicate regionally widespread presence of radiocarbon. This unstable isotope with half life of 5,730 years should decay to nil if the analyzed subglacial sediment samples have been isolated beneath the ice sheet from the atmosphere and the ocean for 125,000 years (over 20 half lives). However, the apparent radiocarbon ages for these samples are in the range of about 20,000-30,000 years BP, based on radiocarbon Fraction Modern (FM) of a few to several percent. The apparent sediment ages cannot be taken at face value because: (1) they overlap with the Last Glacial Maximum (LGM) when WAIS is known to have extended over 1,000 km past the sediment sampling locations, and (2) Antarctic glacigenic sediments commonly contain significant admixture of old, radiocarbon-dead organic matter. The latter biases apparent radiocarbon ages because it violates the assumption that the initial radiocarbon fraction in a sample was equal to FM. To mitigate the problem with apparent ages, we assume that initial radiocarbon fraction in subglacial sediments was equal to that determined by us independently in J-9 sediments from beneath the Ross Ice Shelf (RIS) and calculate radiocarbon 'model ages' between 1,000 and 6,000 years BP. This period of time overlaps with a regional climatic optimum and with late phases of post-LGM glacioisostatic adjustment in the region (e.g., Kingslake et al., this session). We propose that the grounding line of WAIS, at least on the RIS side, retreated in mid/late Holocene more than 300 km beyond its current position and then re-advanced to reach its modern geometry. This implies that the main body of WAIS was significantly smaller than today in mid/late Holocene and that the ice sheet is capable of

Comparing the Palmer Drought Index and the Standardized Precipitation Index for Zagreb Gric Observatory

NASA Astrophysics Data System (ADS)

Pandzic, K.; Likso, T.

2012-04-01

Conventional Palmer Drought Index (PDI) and recent Standardized Precipitation Index (SPI) for Zagreb Gric Observatory are compared by spectral analysis technique. Data for a period 1862-2010 are used. The results indicate that SPI is simpler for interpretation but PDI more comprehensive index. On the other side, lack of temperature within SPI, make impossible application of it on climate change interpretation. Possible applications of them in irrigation scheduling system is considered as well for drought risk assessment.

AMS radiocarbon dating and varve chronology of Lake Soppensee: 6000 to 12000 14C years BP

NASA Astrophysics Data System (ADS)

Hajdas, Irena; Ivy, Susan D.; Beer, Jürg; Bonani, Georges; Imboden, Dieter; Lotted, André F.; Sturm, Michael; Suter, Martin

1993-12-01

For the extension of the radiocarbon calibration curve beyond 10000 14C y BP, laminated sediment from Lake Soppensee (central Switzerland) was dated. The radiocarbon time scale was obtained using accelerator mass spectrometry (AMS) dating of terrestrial macrofossils selected from the Soppensee sediment. Because of an unlaminated sediment section during the Younger Dryas (10000 11000 14C y BP), the absolute time scale, based on counting annual layers (varves), had to be corrected for missing varves. The Soppensee radiocarbon-verve chronology covers the time period from 6000 to 12000 14C y BP on the radiocarbon time scale and 7000 to 13000 calendar y BP on the absolute time scale. The good agreement with the tree ring curve in the interval from 7000 to 11450 cal y BP (cal y indicates calendar year) proves the annual character of the laminations. The ash layer of the Vasset/Killian Tephra (Massif Central, France) is dated at 8230±140 14C y BP and 9407±44 cal y BP. The boundaries of the Younger Dryas biozone are placed at 10986±69 cal y BP (Younger Dryas/Preboreal) and 1212±86 cal y BP (Alleröd/Younger Dryas) on the absolute time scale. The absolute age of the Laacher See Tephra layer, dated with the radiocarbon method at 10 800 to 11200 14C y BP, is estimated at 12350 ± 135 cal y BP. The oldest radiocarbon age of 14190±120 14C y BP was obtained on macrofossils of pioneer vegetation which were found in the lowermost part of the sediment profile. For the late Glacial, the offset between the radiocarbon (10000 12000 14C y BP) and the absolute time scale (11400 13000 cal y BP) in the Soppensee chronology is not greater than 1000 years, which differs from the trend of the U/Th-radiocarbon curve derived from corals.

Extraneous carbon assessment in ultra-microscale radiocarbon analysis using benzene polycarboxylic acids (BPCA)

NASA Astrophysics Data System (ADS)

Hanke, Ulrich M.; McIntyre, Cameron P.; Schmidt, Michael W. I.; Wacker, Lukas; Eglinton, Timothy I.

2016-04-01

Measurements of the natural abundance of radiocarbon (14C) concentrations in inorganic and organic carbon-containing materials can be used to investigate their date of origin. Particularly, the biogeochemical cycling of specific compounds in the environment may be investigated applying molecular marker analyses. However, the isolation of specific molecules from environmental matrices requires a complex processing procedure resulting in small sample sizes that often contain less than 30 μg C. Such small samples are sensitive to extraneous carbon (Cex) that is introduced during the purification of the compounds (Shah and Pearson, 2007). We present a thorough radiocarbon blank assessment for benzene polycarboxylic acids (BPCA), a proxy for combustion products that are formed during the oxidative degradation of condensed polyaromatic structures (Wiedemeier et al, in press). The extraneous carbon assessment includes reference material for (1) chemical extraction, (2) preparative liquid chromatography (3) wet chemical oxidation which are subsequently measured with gas ion source AMS (Accelerator Mass Spectrometer, 5-100 μg C). We always use pairs of reference materials, radiocarbon depleted (14Cfossil) and modern (14Cmodern) to determine the fraction modern (F14C) of Cex.Our results include detailed information about the quantification of Cex in radiocarbon molecular marker analysis using BPCA. Error propagation calculations indicate that ultra-microscale samples (20-30 μg) are feasible with uncertainties of less than 10 %. Calculations of the constant contamination reveal important information about the source (F14C) and mass (μg) of Cex (Wacker and Christl, 2011) for each sub procedure. An external correction of compound specific radiocarbon data is essential for robust results that allow for a high degree of confidence in the 14C results. References Shah and Pearson, 2007. Ultra-microscale (5-25μg C) analysis of individual lipids by 14C AMS: Assessment and

Radiocarbon dating of planktonic foraminifer shells: A cautionary tale

NASA Astrophysics Data System (ADS)

Mekik, Figen

2014-01-01

rate, bioturbation, winnowing, and calcite dissolution produce significant radiocarbon age offsets among multiple species of coexisting planktonic foraminifers and pteropod fragments. We compare the radiocarbon age of foraminifer species and pteropod fragments with estimates of percent calcite dissolved made with a sedimentary proxy (Globorotalia menardii fragmentation index—MFI) to delineate the effect of dissolution on radiocarbon age of foraminifers. Data from two core top transects on the Rio Grande Rise (RIO) and Ontong Java Plateau (OJP) and from down core sediments of varying sedimentation rates in the tropical Pacific (ME-27, MD98 2177, and MW91-9 56GGC) reveal that sediments with the greatest accumulation rates produce the least age offsets among coexisting species. Age offsets among coexisting foraminifers are about 3500 years on RIO, and 1000 years on OJP. Two core tops from RIO yield an age of the Last Glacial Maximum possibly due to mass displacement of younger sediments downslope. Foraminifer age increases with increasing dissolution and there is a consistent pattern of older foraminifer fragments coexisting with younger whole shells of the same species. The only exception is sediments which have experienced high dissolution where fragments are younger than whole shells. The age offset between fragments of G. menardii and its coexisting whole shells does not exceed the age offset among other coexisting foraminifer species in the same core tops.

Late Holocene Radiocarbon Variability in Northwest Atlantic Slope Waters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sherwood, O; Edinger, E; Guilderson, T P

2008-08-15

Deep-sea gorgonian corals secrete a 2-part skeleton of calcite, derived from dissolved inorganic carbon at depth, and gorgonin, derived from recently fixed and exported particulate organic matter. Radiocarbon contents of the calcite and gorgonin provide direct measures of seawater radiocarbon at depth and in the overlying surface waters, respectively. Using specimens collected from Northwest Atlantic slope waters, we generated radiocarbon records for surface and upper intermediate water layers spanning the pre- and post bomb-{sup 14}C eras. In Labrador Slope Water (LSW), convective mixing homogenizes the pre-bomb {Delta}{sup 14}C signature (-67 {+-} 4{per_thousand}) to at least 1000 m depth. Surface watermore » bomb-{sup 14}C signals were lagged and damped (peaking at {approx} +45{per_thousand} in the early 1980s) relative to other regions of the northwest Atlantic, and intermediate water signals were damped further. Off southwest Nova Scotia, the vertical gradient in {Delta}{sup 14}C is much stronger. In surface water, pre-bomb {Delta}{sup 14}C averaged -75 {+-} 5{per_thousand}. At 250-475 m depth, prebomb {Delta}{sup 14}C oscillated quasi-decadally between -80 and -100{per_thousand}, likely reflecting interannual variability in the presence of Labrador Slope Water vs. Warm Slope Water (WSW). Finally, subfossil corals reveal no systematic changes in vertical {Delta}{sup 14}C gradients over the last 1200 years.« less

Ambulatory oral surgery: 1-year experience with 11 680 patients from Zagreb district, Croatia

PubMed Central

Jokić, Dražen; Macan, Darko; Perić, Berislav; Tadić, Marinka; Biočić, Josip; Đanić, Petar; Brajdić, Davor

2013-01-01

Aim To examine the types and frequencies of oral surgery diagnoses and ambulatory oral surgical treatments during one year period at the Department of Oral Surgery, University Hospital Dubrava in Zagreb, Croatia. Methods Sociodemographic and clinical data on 11 680 ambulatory patients, treated between January 1 and of December 31, 2011 were retrieved from the hospital database using a specific protocol. The obtained data were subsequently analyzed in order to assess the frequency of diagnoses and differences in sex and age. Results The most common ambulatory procedure was tooth extraction (37.67%) and the most common procedure in ambulatory operating room was alveolectomy (57.25%). The test of proportions showed that significantly more extractions (P < 0.001) and intraoral incisions (P < 0.001) were performed among male patients, whereas significantly more alveolectomies and apicoectomies were performed among female patients (P < 0.001). A greater prevalence of periodontal disease was found in patients residing in Zagreb than in patients residing in rural areas. Conclusion The data from this study may be useful for planning of ambulatory oral surgery services, budgeting, and sustaining quality improvement, enhancing oral surgical curricula, training and education of primary health care doctors and oral surgery specialists, and promoting patients’ awareness of the importance of oral health. PMID:23444246

Surface Ocean Radiocarbon Reservoir Ages From Land-Sea Tephra Correlation Constrains Deglacial Chronology and Ocean Circulation in the Southeast Bering Sea

NASA Astrophysics Data System (ADS)

Cook, M. S.; Miller, R.; White-Nockleby, C.; Chapman, A.; Mix, A. C.

2017-12-01

Radiocarbon estimates of the past ocean are valuable because unlike passive tracers, radiocarbon has the potential to trace both the distribution and rate of transport of water masses. Most studies using paired radiocarbon measurements on planktonic and benthic foraminifera assume that the surface reservoir age was constant at the preindustrial value, which if incorrect, can strongly bias radiocarbon reconstructions. The subarctic Pacific is ringed by volcanic arcs, and there is great potential to use tephrochronology as a stratigraphic tool in sediments from the last glacial and deglaciation, and assign calendar ages to the marine sediment without relying on calibrated planktonic radiocarbon ages. In this study, we use major and trace element analysis of volcanic glass to match tephras between radiocarbon-dated lake cores from Sanak Island in the eastern Aleutians to marine cores from Umnak Plateau in the southeast Bering Sea. There are numerous thin tephras preserved in laminated sediments from the Bolling-Allerod and early Holocene in marine cores from depths (1000-1500 m) within the modern oxygen minimum zone. We find that trace elements are crucial in distinguishing tephras from individual eruptions. Our preliminary radiocarbon measurements suggest that the benthic-atmosphere radiocarbon differences and marine surface reservoir ages in the Bolling-Allerod are similar to pre-industrial values, supporting previously published radiocarbon reconstructions from the region.

RADIOCARBON ANALYSIS OF PM 2.5 AMBIENT AEROSOL

EPA Science Inventory

The radiocarbon (14C) content of an ambient aerosol sample can be directly related to the fraction of the sample's total carbon mass contributed by natural (biogenic) sources. Such knowledge is difficult to determine by other means, and important for devising ambient PM contro...

RADIOCARBON MEASUREMENTS ON PM-2.5 AMBIENT AEROSOL

EPA Science Inventory

Radiocarbon (14C) measurements provide an estimate of the fraction of carbon in a sample that is biogenic. The methodology has been extensively used in past wintertime studies to quantify the contribution of wood smoke to ambient aerosol. In summertime such measurements can p...

The Pattern of Antibiotic Prescribing by Dental Practitioners in Zagreb, Croatia.

PubMed

Perić, Marina; Perković, Ivana; Romić, Martina; Simeon, Paris; Matijević, Jurica; Mehičić, Goranka Prpić; Krmek, Silvana Jukić

2015-06-01

Bacterial resistance is considered a consequence of misuse or overuse of antibiotics. Dentistry significantly contributes to this increasing public health problem. The aim of this cross-sectional study was to examine the pattern of antibiotics prescribed by Croatian dentists in Zagreb area. Out of 220 Doctors of Dental Medicine (DMDs) from Zagreb 110 responded to survey. Prior to the research an ethical approval was obtained. Participants were directly contacted. The questionnaire consisted of two parts: general data on DMDs and the part concerning indications, duration, type and dosage of antibiotic therapy. Data were processed using MS Excel and SPSS for Windows, Version 17.0. Statistical significance was tested by Fisher's exact test, chi-square test, Mann-Whitney U test and Spearman's rank correlation at the level of statistical significance p<0.05. During the period of two months, the doctors prescribed antibiotics to 1,500 patients, 690 (46%) were men and 810 (54%) women. The most often prescribed antibiotics were penicillin (72.5% of patients), represented mostly by amoxicillin in combination with clavulanic acid (57.6%). The most common indication for the prescribed antibiotics was periapical or periodontal abscess (44%). Definite clinical indication (71.2%) was stated as the most common reason for antibiotic prescription. Antibiotic therapy usually lasted 7 days (62.9%). The doctors prescribed daily doses of antibiotics according to the instructions for the use of specific drugs. The examined subjects prescribe antibiotics according to the curriculum taught at the School of Dental Medicine for majority of types, doses and duration of the treatments, although antibiotics over-prescription in cases without medical indication was observed. The national guidelines on antibiotic regimens are required in order to reduce unnecessary antibiotic use. Copyright© by the National Institute of Public Health, Prague 2015.

Towards constraining the stratosphere-troposphere exchange of radiocarbon: strategies of stratospheric 14CO2 measurements using AirCore

NASA Astrophysics Data System (ADS)

Chen, Huilin; Paul, Dipayan; Meijer, Harro; Miller, John; Kivi, Rigel; Krol, Maarten

2016-04-01

Radiocarbon (14C) plays an important role in the carbon cycle studies to understand both natural and anthropogenic carbon fluxes, but also in atmospheric chemistry to constrain hydroxyl radical (OH) concentrations in the atmosphere. Apart from the enormous 14C emissions from nuclear bomb testing in the 1950s and 1960s, radiocarbon is primarily produced in the stratosphere due to the cosmogenic production. To this end, better understanding the stratospheric radiocarbon source is very useful to advance the use of radiocarbon for these applications. However, stratospheric 14C observations have been very limited so that there are large uncertainties on the magnitude and the location of the 14C production as well as the transport of radiocarbon from the stratosphere to the troposphere. Recently we have successfully made stratospheric 14C measurements using AirCore samples from Sodankylä, Northern Finland. AirCore is an innovative atmospheric sampling system, which passively collects atmospheric air samples into a long piece of coiled stainless steel tubing during the descent of a balloon flight. Due to the relatively low cost of the consumables, there is a potential to make such AirCore profiling in other parts of the world on a regular basis. In this study, we simulate the 14C in the atmosphere and assess the stratosphere-troposphere exchange of radiocarbon using the TM5 model. The Sodankylä radiocarbon measurements will be used to verify the performance of the model at high latitude. Besides this, we will also evaluate the influence of different cosmogenic 14C production scenarios and the uncertainties in the OH field on the seasonal cycles of radiocarbon and on the stratosphere-troposphere exchange, and based on the results design a strategy to set up a 14C measurement program using AirCore.

A randomized open-labeled study to demonstrate the non-inferiority of purified chick-embryo cell rabies vaccine administered in the Zagreb regimen (2-1-1) compared with the Essen regimen in Chinese adults.

PubMed

Ma, Jingchen; Wang, Hongchang; Li, Jun; Chang, Likuan; Xie, Yun; Liu, Zhonglin; Zhao, Yuliang; Malerczyk, Claudius; Claudius, Malerczyk

2014-01-01

The Zagreb regimen has been used for 20 years in various countries. In China, until 2010, the Zagreb schedule was only approved for purified chick embryo cell vaccine (PCECV) and purified Vero cell rabies vaccines (PVRV). In this phase III clinical trial, we aimed to demonstrate the safety and immunogenic non-inferiority of the Zagreb regimen compared with the Essen regimen in healthy adult Chinese immunized with PCECV (Rabipur®). The study enrolled 825 subjects aged 18 to 50 years; serum samples were collected on Days 0, 7, 14, 42, and at 13 months to assess rabies virus neutralizing antibody (RVNA) concentrations. Solicited and unsolicited local and systemic reactions were recorded for 6 days following the day of vaccination, and collected throughout the entire study period (Day 1 until Month 13). The Zagreb regimen was non-inferior to the Essen regimen with regard to RVNA concentrations after 7, 14, and 42 days, and 13 months of immunization. The non-inferiority of seroconversion was established at Days 14 and 42. The incidence of local and systemic reactions was similar between groups, and mostly of mild or moderate severity. Vaccine-related adverse events occurred more frequently in the Essen group than in the Zagreb group. Vaccination with PCECV under a 2-1-1 regimen is as safe and immunogenic as under the traditional 5-dose Essen regimen for rabies post-exposure prophylaxis, and is a more cost-effective option, has a more practical vaccination schedule, and can potentially increase compliance.

A randomized open-labeled study to demonstrate the non-inferiority of purified chick-embryo cell rabies vaccine administered in the Zagreb regimen (2-1-1) compared with the Essen regimen in Chinese adults

PubMed Central

Ma, Jingchen; Wang, Hongchang; Li, Jun; Chang, Likuan; Xie, Yun; Liu, Zhonglin; Zhao, Yuliang; Claudius, Malerczyk

2014-01-01

The Zagreb regimen has been used for 20 years in various countries. In China, until 2010, the Zagreb schedule was only approved for purified chick embryo cell vaccine (PCECV) and purified Vero cell rabies vaccines (PVRV). In this phase III clinical trial, we aimed to demonstrate the safety and immunogenic non-inferiority of the Zagreb regimen compared with the Essen regimen in healthy adult Chinese immunized with PCECV (Rabipur®). The study enrolled 825 subjects aged 18 to 50 years; serum samples were collected on Days 0, 7, 14, 42, and at 13 months to assess rabies virus neutralizing antibody (RVNA) concentrations. Solicited and unsolicited local and systemic reactions were recorded for 6 days following the day of vaccination, and collected throughout the entire study period (Day 1 until Month 13). The Zagreb regimen was non-inferior to the Essen regimen with regard to RVNA concentrations after 7, 14, and 42 days, and 13 months of immunization. The non-inferiority of seroconversion was established at Days 14 and 42. The incidence of local and systemic reactions was similar between groups, and mostly of mild or moderate severity. Vaccine-related adverse events occurred more frequently in the Essen group than in the Zagreb group. Vaccination with PCECV under a 2-1-1 regimen is as safe and immunogenic as under the traditional 5-dose Essen regimen for rabies post-exposure prophylaxis, and is a more cost-effective option, has a more practical vaccination schedule, and can potentially increase compliance. PMID:25483635

Radiocarbon evidence for a smaller oceanic carbon dioxide sink than previously believed

NASA Astrophysics Data System (ADS)

Hesshaimer, Vago; Heimann, Martin; Levin, Ingeborg

1994-07-01

RADIOCARBON produced naturally in the upper atmosphere or arti-ficially during nuclear weapons testing is the main tracer used to validate models of oceanic carbon cycling, in particular the exchange of carbon dioxide with the atmosphere1-3 and the mixing parameters within the ocean itself4-7. Here we test the overall consistency of exchange fluxes between all relevant compartments in a simple model of the global carbon cycle, using measurements of the long-term tropospheric CO2 concentration8 and radiocarbon composition9-12, the bomb 14C inventory in the stratosphere13,14 and a compilation of bomb detonation dates and strengths15. We find that to balance the budget, we must invoke an extra source to account for 25% of the generally accepted uptake of bomb 14C by the oceans3. The strength of this source decreases from 1970 onwards, with a characteristic timescale similar to that of the ocean uptake. Significant radiocarbon transport from the remote high stratosphere and significantly reduced uptake of bomb 14C by the biosphere can both be ruled out by observational constraints. We therefore conclude that the global oceanic bomb 14C inventory should be revised downwards. A smaller oceanic bomb 14C inventory also implies a smaller oceanic radiocarbon penetration depth16, which in turn implies that the oceans take up 25% less anthropogenic CO2 than had previously been believed.

Decadally resolved Lateglacial radiocarbon evidence from New Zealand kauri

NASA Astrophysics Data System (ADS)

Hogg, Alan; Southon, John; Turney, Chris; Palmer, Jonathan; Bronk Ramsey, Christopher; Fenwick, Pavla; Boswijk, Gretel; Büntgen, Ulf; Friedrich, Michael; Helle, Gerhard; Hughen, Konrad; Jones, Richard; Kromer, Bernd; Noronha, Alexandra; Reinig, Frederick; Reynard, Linda; Staff, Richard; Wacker, Lukas

2017-04-01

The Last Glacial-Interglacial Transition (LGIT; 15,000 - 11,000 cal BP) was characterised by complex spatiotemporal patterns of climate change, with numerous studies requiring accurate chronological control to decipher leads from lags in global palaeoclimatic, -environmental and archaeological records. However, close scrutiny of the few available tree-ring chronologies and radiocarbon-dated sequences composing the IntCal13 radiocarbon (14C) calibration curve, indicates significant weakness in 14C calibration across key periods of the LGIT. Here, we present a decadally-resolved atmospheric 14C record derived from New Zealand kauri spanning Greenland Stadial 1 (GS-1; 12,900 - 11,650 cal BP). Two floating kauri 14C time series, curve-matched to IntCal13, serve as a radiocarbon backbone through GS-1. Floating Northern Hemisphere (NH) 14C datasets are matched against the new kauri data, forming a robust NH 14C time series to 14,200 cal BP. Our results show that IntCal13 is questionable from 12,200 - 11,900 cal BP and the 10,400 BP 14C plateau is approximately five decades too short. By precisely aligning Southern and Northern Hemisphere tree-ring 14C records with marine 14C sequences, we document two relatively short periods of North Atlantic Meridional Overturning Circulation (AMOC) collapse during GS-1. Hence, sustained North Atlantic cooling across GS-1 was not driven by a prolonged AMOC reduction but was probably due to an equatorward migration of the Polar Front.

The radiocarbon budget for Mono Lake: an unsolved mystery

USGS Publications Warehouse

Broecker, W.S.; Wanninkhof, R.; Mathieu, G.; Peng, T.-H.; Stine, S.; Robinson, S.; Herczeg, A.; Stuiver, M.

1988-01-01

Since 1957 the 14C C ratio of the dissolved inorganic carbon in Mono Lake has risen by about 60???. The magnitude of this increase is about four times larger than that expected from the invasion of bomb-produced 14C from the atmosphere. We have eliminated the following explanations: (1) measurement error, (2) an unusually high physical exchange rate for non-reactive gases, (3) inorganic enhancement of the CO2 exchange rate, and (4) biological enhancement of the CO2 exchange rate. Clandestine disposal of waste radiocarbon remains a dark-horse explanation. In the course of our investigations we have uncovered evidence for at least one episodic input of radiocarbon-free carbon to the lake over the last 1000 years. We speculate that this injection was related to a hydrothermal event resulting from sublacustrine volcanic activity. ?? 1988.

New Hydroxyproline Radiocarbon Dates from Sungir, Russia, Confirm Early Mid Upper Palaeolithic Burials in Eurasia

PubMed Central

Nalawade-Chavan, Shweta; McCullagh, James; Hedges, Robert

2014-01-01

Sungir (Russia) is a key Mid-Upper Palaeolithic site in Eurasia, containing several spectacular burials that disclose early evidence for complex burial rites in the form of a range of grave goods deposited along with the dead. Dating has been particularly challenging, with multiple radiocarbon dates ranging from 19,160±270 to 28,800±240 BP for burials that are believed to be closely similar in age. There are disparities in the radiocarbon dates of human bones, faunal remains and charcoal found on the floor of burials [1], [2], [3]. Our approach has been to develop compound-specific methods using High Performance Liquid Chromatography (HPLC) to separate single amino acids, such as hydroxyproline, and thereby avoid the known human contamination on the bones themselves. Previously, we applied this technique to obtain radiocarbon dates of ∼30,000 BP for Sungir 2, Sungir 3 and a mammoth bone from the occupation levels of the site [4]. The single amino acid radiocarbon dates were in good agreement with each other compared to all the dates previously reported, supporting their reliability. Here we report new hydroxyproline dates for two more human burials from the same site, Sungir 1 and Sungir 4. All five hydroxyproline dates reported are statistically indistinguishable and support an identical age for the group. The results suggest that compound-specific radiocarbon analysis should be considered seriously as the method of choice when precious archaeological remains are to be dated because they give a demonstrably contaminant-free radiocarbon age. The new ages are, together with the previously dated ‘Red Lady of Paviland’ human in the British Isles, the earliest for Mid Upper Palaeolithic burial behaviour in Eurasia, and point to the precocious appearance of this form of rite in Europe Russia. PMID:24416120

New hydroxyproline radiocarbon dates from Sungir, Russia, confirm early Mid Upper Palaeolithic burials in Eurasia.

PubMed

Nalawade-Chavan, Shweta; McCullagh, James; Hedges, Robert

2014-01-01

Sungir (Russia) is a key Mid-Upper Palaeolithic site in Eurasia, containing several spectacular burials that disclose early evidence for complex burial rites in the form of a range of grave goods deposited along with the dead. Dating has been particularly challenging, with multiple radiocarbon dates ranging from 19,160±270 to 28,800±240 BP for burials that are believed to be closely similar in age. There are disparities in the radiocarbon dates of human bones, faunal remains and charcoal found on the floor of burials. Our approach has been to develop compound-specific methods using High Performance Liquid Chromatography (HPLC) to separate single amino acids, such as hydroxyproline, and thereby avoid the known human contamination on the bones themselves. Previously, we applied this technique to obtain radiocarbon dates of ∼30,000 BP for Sungir 2, Sungir 3 and a mammoth bone from the occupation levels of the site. The single amino acid radiocarbon dates were in good agreement with each other compared to all the dates previously reported, supporting their reliability. Here we report new hydroxyproline dates for two more human burials from the same site, Sungir 1 and Sungir 4. All five hydroxyproline dates reported are statistically indistinguishable and support an identical age for the group. The results suggest that compound-specific radiocarbon analysis should be considered seriously as the method of choice when precious archaeological remains are to be dated because they give a demonstrably contaminant-free radiocarbon age. The new ages are, together with the previously dated 'Red Lady of Paviland' human in the British Isles, the earliest for Mid Upper Palaeolithic burial behaviour in Eurasia, and point to the precocious appearance of this form of rite in Europe Russia.

The knowledge and understanding of preanalytical phase among biomedicine students at the University of Zagreb

PubMed Central

Dukic, Lora; Jokic, Anja; Kules, Josipa; Pasalic, Daria

2016-01-01

Introduction The educational program for health care personnel is important for reducing preanalytical errors and improving quality of laboratory test results. The aim of our study was to assess the level of knowledge on preanalytical phase in population of biomedicine students through a cross-sectional survey. Materials and methods A survey was sent to students on penultimate and final year of Faculty of Pharmacy and Biochemistry – study of medical biochemistry (FPB), Faculty of Veterinary Medicine (FVM) and School of Medicine (SM), University of Zagreb, Croatia, using the web tool SurveyMonkey. Survey was composed of demographics and 14 statements regarding the preanalytical phase of laboratory testing. Comparison of frequencies and proportions of correct answers was done with Fisher’s exact test and test of comparison of proportions, respectively. Results Study included 135 participants, median age 24 (23-40) years. Students from FPB had higher proportion of correct answers (86%) compared to students from other biomedical faculties 62%, P < 0.001. Students from FPB were more conscious of the importance of specimen mixing (P = 0.027), prevalence of preanalytical errors (P = 0.001), impact of hemolysis (P = 0.032) and lipemia interferences (P = 0.010), proper choice of anticoagulants (P = 0.001), transport conditions for ammonia sample (P < 0.001) and order of draw during blood specimen collection (P < 0.001), in comparison with students from SM and FVM. Conclusions Students from FPB are more conscious of the importance of preanalytical phase of testing in comparison with their colleagues from other biomedical faculties. No difference in knowledge between penultimate and final year of the same faculty was found. PMID:26981023

An analysis of carbon and radiocarbon profiles across a range ecosystems types

NASA Astrophysics Data System (ADS)

Heckman, K. A.; Gallo, A.; Hatten, J. A.; Swanston, C.; Strahm, B. D.; Sanclements, M.

2016-12-01

Soil carbon stocks have become recognized as increasingly important in the context of climate change and global C cycle modeling. As modelers seek to identify key parameters affecting the size and stability of belowground C stocks, attention has been drawn to the mineral matrix and the soil physiochemical factors influenced by it. Though clay content has often been utilized as a convenient and key explanatory variable for soil C dynamics, its utility has recently come under scrutiny as new paradigms of soil organic matter stabilization have been developed. We utilized soil cores from a range of National Ecological Observatory Network (NEON) experimental plots to examine the influence of mineralogical parameters on soil C stocks and turnover and their relative importance in comparison to climatic variables. Results are presented for a total of 11 NEON sites, spanning Alfisols, Entisols, Mollisols and Spodosols. Soils were sampled by genetic horizon, density separated according to density fractionation: light fractions (particulate organics neither occluded within aggregates nor associated with mineral surfaces), occluded fractions (particulate organics occluded within aggregates), and heavy fractions (organics associated with mineral surfaces). Bulk soils and density fractions were measured for % C and radiocarbon abundance (as a measure of C stability). Carbon and radiocarbon abundances were examined among fractions and in the context of climatic variables (temperature, precipitation, elevation) and soil physiochemical variables (% clay and pH). No direct relationships between temperature and soil C or radiocarbon abundances were found. As a whole, soil radiocarbon abundance in density fractions decreased in the order of light>heavy>occluded, highlighting the importance of both surface sorption and aggregation to the preservation of organics. Radiocarbon concentrations of the heavy fraction (mineral adsorbed) were significantly, though weakly, correlated with pH (r

RADIOCARBON MEASUREMENT OF THE BIOGENIC CONTRIBUTION TO SUMMERTIME PM 2.5 AMBIENT AEROSOL IN NASHVILLE, TN

EPA Science Inventory

Radiocarbon (14C) measurements performed on PM-2.5 samples collected near Nashville, TN from June 21 to July 13, 1999, showed high levels of modern carbon, ranging from 56 to 80% of the total carbon in the samples. Radiocarbon measurements performed on dichloromethane extracts of...

Analysis of Artificial Radiocarbon in Different Skeletal and Dental Tissue Types to Evaluate Date of Death

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ubelaker, D H; Buchholz, B A; Stewart, J

Radiocarbon dating, with special reference to the modern bomb-curve, can provide useful information to elucidate the date of death of skeletonized human remains. Interpretation can be enhanced with analysis of different types of tissues within a single skeleton because of the known variability of formation times and remodeling rates. Analysis of radiocarbon content of teeth, especially the enamel in tooth crowns provides information about the date of formation in the childhood years and in consideration of the known timing of tooth formation can be used to estimate the birth date after 1950 A.D. Radiocarbon analysis of modern cortical and trabecularmore » bone samples from the same skeleton may allow proper placement on the pre-1963 or post-1963 sides of the bomb-curve since most trabecular bone generally undergoes more rapid remodeling than does most cortical bone. Pre-1963 bone formation would produce higher radiocarbon values for most trabecular bone than for most cortical bone. This relationship is reversed for formation after 1963. Radiocarbon analysis was conducted in this study on dental, cortical and trabecular bone samples from two adult individuals of known birth (1925 and 1926) and death dates (1995 and 1959). As expected, the dental results correspond to pre-bomb bomb-curve values reflecting conditions during the childhoods of the individuals. The curve radiocarbon content of most bone samples reflected the higher modern bomb-curve values. Within the bone sample analyses, the values of the trabecular bone were higher than those of cortical bone and supported the known placement on the pre-1963 side of the bomb-curve.« less

Combined dendrochronological and radiocarbon dating of six Russian icons from the 15th-17th centuries

NASA Astrophysics Data System (ADS)

Dolgikh, A. V.; Matskovsky, V. V.; Voronin, K. V.; Solomina, O. N.

2017-06-01

The results of dendrochronological and radiocarbon dating by means of accelerator mass spectrometry (AMS) of six medieval icons, originating from northern European Russia and painted on wooden panels made from Scots pine, dated to the 15th to 17th centuries are presented. The panels of each icon were studied using dendrochronology. Five to six AMS dates were obtained for four icons. Although five icons were dendro-dated successfully, one failed to be reliably cross-dated with the existing master tree-ring chronologies and it was dated by radiocarbon wiggle-matching. Dendrochronological dating and wiggle-matching of radiocarbon dates allowed us to determine the narrow chronological intervals of icon creation.

Revised age of deglaciation of Lake Emma based on new radiocarbon and macrofossil analyses

USGS Publications Warehouse

Elias, S.A.; Carrara, P.E.; Toolin, L.J.; Jull, A.J.T.

1991-01-01

Previous radiocarbon ages of detrital moss fragments in basal organic sediments of Lake Emma indicated that extensive deglaciation of the San Juan Mountains occurred prior to 14,900 yr B.P. (Carrara et al., 1984). Paleoecological analyses of insect and plant macrofossils from these basal sediments cast doubt on the reliability of the radiocarbon ages. Subsequent accelerator radiocarbon dates of insect fossils and wood fragments indicate an early Holocene age, rather than a late Pleistocene age, for the basal sediments of Lake Emma. These new radiocarbon ages suggest that by at least 10,000 yr B.P. deglaciation of the San Juan Mountains was complete. The insect and plant macrofossils from the basal organic sediments indicate a higher-than-present treeline during the early Holocene. The insect assemblages consisted of about 30% bark beetles, which contrasts markedly with the composition of insects from modern lake sediments and modern specimens collected in the Lake Emma cirque, in which bark beetles comprise only about 3% of the assemblages. In addition, in the fossil assemblages there were a number of flightless insect species (not subject to upslope transport by wind) indicative of coniferous forest environments. These insects were likewise absent in the modern assemblage. ?? 1991.

Radiocarbon as a Novel Tracer of Extra-Antarctic Feeding in Southern Hemisphere Humpback Whales.

PubMed

Eisenmann, Pascale; Fry, Brian; Mazumder, Debashish; Jacobsen, Geraldine; Holyoake, Carlysle Sian; Coughran, Douglas; Bengtson Nash, Susan

2017-06-29

Bulk stable isotope analysis provides information regarding food web interactions, and has been applied to several cetacean species for the study of migration ecology. One limitation in bulk stable isotope analysis arises when a species, such as Southern hemisphere humpback whales, utilises geographically distinct food webs with differing isotopic baselines. Migrations to areas with different baselines can result in isotopic changes that mimic changes in feeding relations, leading to ambiguous food web interpretations. Here, we demonstrate the novel application of radiocarbon measurement for the resolution of such ambiguities. Radiocarbon was measured in baleen plates from humpback whales stranded in Australia between 2007 and 2013, and in skin samples collected in Australia and Antarctica from stranded and free-ranging animals. Radiocarbon measurements showed lower values for Southern Ocean feeding than for extra-Antarctic feeding in Australian waters. While the whales mostly relied on Antarctic-derived energy stores during their annual migration, there was some evidence of feeding within temperate zone waters in some individuals. This work, to our knowledge, provides the first definitive biochemical evidence for supplementary feeding by southern hemisphere humpback whales within temperate waters during migration. Further, the work contributes a powerful new tool (radiocarbon) for tracing source regions and geographical feeding.

Radiocarbon Depression in Aquatic Foodwebs of the Colorado River, USA: Coupling Between Carbonate Weathering and the Biosphere

NASA Astrophysics Data System (ADS)

Sickman, J. O.; Huang, W.; Lucero, D.; Anderson, M.

2012-12-01

The 14C isotopic composition of living organisms is generally considered to be in isotopic equilibrium with atmosphere CO2. During the course of investigations of aquatic foodwebs of the Colorado River, we measured substantial radiocarbon depression of organisms within planktonic and benthic foodwebs of Copper Basin Reservoir, a short residence-time water body at the intake to the Colorado River Aqueduct. All trophic levels had depressed radiocarbon content with inferred "age" of ca. 1,200 radiocarbon years (range: 0.85 to 0.87 fraction modern carbon (fmc)). Additional measurements of the radiocarbon content of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) were made in other major rivers in California (New (near Salton Sea), Santa Ana (near Riverside), San Joaquin (near Fresno) and Salinas (near San Luis Obispo)). In the New River (which is composed primarily of irrigation tailwater derived from the Colorado River), the radiocarbon values for DIC closely matched those found in biota of the Copper Basin Reservoir (0.85 to 0.87 fmc), but radiocarbon values for DOC were slightly higher (0.91 to 0.95 fmc). In the other California rivers, radiocarbon concentrations in DIC were generally below modern and lower than corresponding levels in DOC; in the case of the Santa Ana River, DOC was older than DIC as a result of wastewater inputs from upstream treatment plants. Together these data suggest that the carbonate equilibrium of California rivers is influenced by weathering of carbonate minerals which produces HCO3- with no 14C. We hypothesize that this dead carbon can move into aquatic foodwebs via algae and phytoplankton uptake during photosynthesis, depressing the 14C content of aquatic foodwebs below that of the atmosphere. Based on a simple two-component mixing model incorporating carbonate weathering and atmospheric CO2, we estimate that 15-17% of the carbon in the aquatic foodweb of Copper Basin is derived directly from mineral weathering of

Collagen Fingerprinting: A New Screening Technique for Radiocarbon Dating Ancient Bone.

PubMed

Harvey, Virginia L; Egerton, Victoria M; Chamberlain, Andrew T; Manning, Phillip L; Buckley, Michael

2016-01-01

Collagen is the dominant organic component of bone and is intimately locked within the hydroxyapatite structure of this ubiquitous biomaterial that dominates archaeological and palaeontological assemblages. Radiocarbon analysis of extracted collagen is one of the most common approaches to dating bone from late Pleistocene or Holocene deposits, but dating is relatively expensive compared to other biochemical techniques. Numerous analytical methods have previously been investigated for the purpose of screening out samples that are unlikely to yield reliable dates including histological analysis, UV-stimulated fluorescence and, most commonly, the measurement of percentage nitrogen (%N) and ratio of carbon to nitrogen (C:N). Here we propose the use of collagen fingerprinting (also known as Zooarchaeology by Mass Spectrometry, or ZooMS, when applied to species identification) as an alternative screening method for radiocarbon dating, due to its ability to provide information on collagen presence and quality, alongside species identification. The method was tested on a series of sub-fossil bone specimens from cave systems on Cayman Brac (Cayman Islands), chosen due to the observable range in diagenetic alteration, and in particular, the extent of mineralisation. Six (14)C dates, of 18 initial attempts, were obtained from remains of extinct hutia, Capromys sp. (Rodentia; Capromyidae), recovered from five distinct caves on Cayman Brac, and ranging from 393 ± 25 to 1588 ± 26 radiocarbon years before present (yr BP). All of the bone samples that yielded radiocarbon dates generated excellent collagen fingerprints, and conversely those that gave poor fingerprints also failed dating. Additionally, two successfully fingerprinted bone samples were screened out from a set of 81. Both subsequently generated (14)C dates, demonstrating successful utilisation of ZooMS as an alternative screening mechanism to identify bone samples that are suitable for 1(4)C analysis.

Collagen Fingerprinting: A New Screening Technique for Radiocarbon Dating Ancient Bone

PubMed Central

Harvey, Virginia L.; Egerton, Victoria M.; Chamberlain, Andrew T.; Manning, Phillip L.; Buckley, Michael

2016-01-01

Collagen is the dominant organic component of bone and is intimately locked within the hydroxyapatite structure of this ubiquitous biomaterial that dominates archaeological and palaeontological assemblages. Radiocarbon analysis of extracted collagen is one of the most common approaches to dating bone from late Pleistocene or Holocene deposits, but dating is relatively expensive compared to other biochemical techniques. Numerous analytical methods have previously been investigated for the purpose of screening out samples that are unlikely to yield reliable dates including histological analysis, UV-stimulated fluorescence and, most commonly, the measurement of percentage nitrogen (%N) and ratio of carbon to nitrogen (C:N). Here we propose the use of collagen fingerprinting (also known as Zooarchaeology by Mass Spectrometry, or ZooMS, when applied to species identification) as an alternative screening method for radiocarbon dating, due to its ability to provide information on collagen presence and quality, alongside species identification. The method was tested on a series of sub-fossil bone specimens from cave systems on Cayman Brac (Cayman Islands), chosen due to the observable range in diagenetic alteration, and in particular, the extent of mineralisation. Six 14C dates, of 18 initial attempts, were obtained from remains of extinct hutia, Capromys sp. (Rodentia; Capromyidae), recovered from five distinct caves on Cayman Brac, and ranging from 393 ± 25 to 1588 ± 26 radiocarbon years before present (yr BP). All of the bone samples that yielded radiocarbon dates generated excellent collagen fingerprints, and conversely those that gave poor fingerprints also failed dating. Additionally, two successfully fingerprinted bone samples were screened out from a set of 81. Both subsequently generated 14C dates, demonstrating successful utilisation of ZooMS as an alternative screening mechanism to identify bone samples that are suitable for 14C analysis. PMID:26938469

Results of Radiocarbon Dating of Holocene Deposits from the Sea of Azov

NASA Astrophysics Data System (ADS)

Matishov, G. G.; Kovaleva, G. V.; Arslanov, Kh. A.; Dyuzhova, K. V.; Polshin, V. V.; Zolotareva, A. E.

2018-04-01

New data on the absolute age of Quaternary bottom deposits from the Sea of Azov based on the results of radiocarbon analysis (14C) are presented. Overall, 67 radiocarbon dating of bottom deposits of New and Ancient Azov Ages were obtained. The thickness of sediments of the New Azov Age and their distribution over different areas of the Sea of Azov was determined during the study; the results obtained were compared with the reference data available. An integrated approach to the study of deposits, based on the combination of the biostratigraphy methods and the results of absolute age dating, was applied.

Complexities in the Use of Bomb-Curve Radiocarbon to Determine Time Since Death of Human Skeletal Remains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ubelaker, D H; Buchholz, B A

2005-04-26

Atmospheric testing of nuclear weapons during the 1950s and early 1960s doubled the level of radiocarbon ({sup 14}C) in the atmosphere. From the peak in 1963, the level of {sup 14}CO{sub 2} has decreased exponentially with a mean life of about 16 years, not due to radioactive decay, but due to mixing with large marine and terrestrial carbon reservoirs. Since radiocarbon is incorporated into all living things, the bomb-pulse is an isotopic chronometer of the past half century. The absence of bomb radiocarbon in skeletonized human remains generally indicates a date of death before 1950. Comparison of the radiocarbon valuesmore » with the post 1950 bomb-curve may also help elucidate when in the post 1950 era, the individual was still alive. Such interpretation however, must consider the age at death of the individual and the type of tissue sampled.« less

Frontal sinus osteoma in a 16th century skeleton from Zagreb, Croatia.

PubMed

Premužić, Zrinka; Rajić Šikanjić, Petra; Mašić, Boris

2013-03-01

The analysis of 16th century graves from Zagreb, Croatia, revealed a case of frontal sinus osteoma in a middle-aged female. This lesion was discovered during visual examination, due to postmortem breakage of the frontal bone. The significance of this finding is based on the fact that frontal sinus osteomas are very rarely reported in the palaeopathological literature, despite the fact that they account for 80% of all paranasal sinus osteomas in modern populations. This paper presents results of macroscopic and radiographic analyses of the lesion, accompanied by a detailed differential diagnosis. Although tumours are commonly considered diseases of modern lifestyles, the described case confirms their occurrence in the past. Copyright © 2013 Elsevier Inc. All rights reserved.

[253 patients with acute pancreatitis treated at the surgical clinic in Zagreb].

PubMed

Bakran, I

1977-01-01

253 patients with acute pancreatitis were treated in clinic for surgery in Zagreb through last 23 years. The most frequent cause of pancreatitis were diseases of biliary tract, obesity, vascular deseases, alcoholism etc. In the symtomatology, the pain was present in all patients and majority of them had abdominal symptoms as well. Most of the patients came to the treatment within the firsts 24 to 48 hours. Besides Trasylol various conservative therapy was applied and some patients were operated either on billiary ducts or on pancreas. 85 patients had to be operated again on billiary tract afterwards. From 253 patients treated 24 died (9,48%) because of the necrosis of pancreas and alterations on various other organs.

High-precision radiocarbon dating and historical biblical archaeology in southern Jordan

PubMed Central

Levy, Thomas E.; Higham, Thomas; Bronk Ramsey, Christopher; Smith, Neil G.; Ben-Yosef, Erez; Robinson, Mark; Münger, Stefan; Knabb, Kyle; Schulze, Jürgen P.; Najjar, Mohammad; Tauxe, Lisa

2008-01-01

Recent excavations and high-precision radiocarbon dating from the largest Iron Age (IA, ca. 1200–500 BCE) copper production center in the southern Levant demonstrate major smelting activities in the region of biblical Edom (southern Jordan) during the 10th and 9th centuries BCE. Stratified radiocarbon samples and artifacts were recorded with precise digital surveying tools linked to a geographic information system developed to control on-site spatial analyses of archaeological finds and model data with innovative visualization tools. The new radiocarbon dates push back by 2 centuries the accepted IA chronology of Edom. Data from Khirbat en-Nahas, and the nearby site of Rujm Hamra Ifdan, demonstrate the centrality of industrial-scale metal production during those centuries traditionally linked closely to political events in Edom's 10th century BCE neighbor ancient Israel. Consequently, the rise of IA Edom is linked to the power vacuum created by the collapse of Late Bronze Age (LB, ca. 1300 BCE) civilizations and the disintegration of the LB Cypriot copper monopoly that dominated the eastern Mediterranean. The methodologies applied to the historical IA archaeology of the Levant have implications for other parts of the world where sacred and historical texts interface with the material record. PMID:18955702

AMS Radiocarbon Dating of Large Za Baobabs (Adansonia za) of Madagascar.

PubMed

Patrut, Adrian; Patrut, Roxana T; Danthu, Pascal; Leong Pock-Tsy, Jean-Michel; Rakosy, Laszlo; Lowy, Daniel A; von Reden, Karl F

2016-01-01

The article reports the radiocarbon investigation of Anzapalivoro, the largest za baobab (Adansonia za) specimen of Madagascar and of another za, namely the Big cistern baobab. Several wood samples collected from the large inner cavity and from the outer part/exterior of the tree were investigated by AMS (accelerator mass spectrometry) radiocarbon dating. For samples collected from the cavity walls, the age values increase with the distance into the wood up to a point of maximum age, after which the values decrease toward the outer part. This anomaly of age sequences indicates that the inner cavity of Anzapalivoro is a false cavity, practically an empty space between several fused stems disposed in a ring-shaped structure. The radiocarbon date of the oldest sample was 780 ± 30 bp, which corresponds to a calibrated age of around 735 yr. Dating results indicate that Anzapalivoro has a closed ring-shaped structure, which consists of 5 fused stems that close a false cavity. The oldest part of the biggest za baobab has a calculated age of 900 years. We also disclose results of the investigation of a second za baobab, the Big cistern baobab, which was hollowed out for water storage. This specimen, which consists of 4 fused stems, was found to be around 260 years old.

An effective method of UV-oxidation of dissolved organic carbon in natural waters for radiocarbon analysis by accelerator mass spectrometry

NASA Astrophysics Data System (ADS)

Xue, Yuejun; Ge, Tiantian; Wang, Xuchen

2015-12-01

Radiocarbon (14C) measurement of dissolved organic carbon (DOC) is a very powerful tool to study the sources, transformation and cycling of carbon in the ocean. The technique, however, remains great challenges for complete and successful oxidation of sufficient DOC with low blanks for high precision carbon isotopic ratio analysis, largely due to the overwhelming proportion of salts and low DOC concentrations in the ocean. In this paper, we report an effective UV-Oxidation method for oxidizing DOC in natural waters for radiocarbon analysis by accelerator mass spectrometry (AMS). The UV-oxidation system and method show 95%±4% oxidation efficiency and high reproducibility for DOC in both river and seawater samples. The blanks associated with the method was also low (about 3 µg C) that is critical for 14C analysis. As a great advantage of the method, multiple water samples can be oxidized at the same time so it reduces the sample processing time substantially compared with other UV-oxidation method currently being used in other laboratories. We have used the system and method for 14C studies of DOC in rivers, estuaries, and oceanic environments and have received promise results.

Radiocarbon content in the annual tree rings during last 150 years and time variation of cosmic rays

NASA Technical Reports Server (NTRS)

Kocharov, G. E.; Metskvarishvili, R. Y.; Tsereteli, S. L.

1985-01-01

The results of the high accuracy measurements of radiocarbon abundance in precisely dated tree rings in the interval 1800 to 1950 yrs are discussed. Radiocarbon content caused by solar activity is established. The temporal dependence of cosmic rays is constructed, by use of radio abundance data.

New radiocarbon dates on the cereals from Wadi Kubbaniya

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wendorf, F.; Schild, R.; Close, A.E.

1984-01-01

In 1978, three carbonized grains of barley and a carbonized grain of einkorn wheat were found in a buried hearth at a Late Paleolithic site at Wadi Kubbaniya in Egypt. In 1981, two large clusters of barley seeds, which were identified as six-row barley and thus domestic, were found at a nearby site of comparable age. Numerous grinding stones, presumed to have been used for processing the cereals, were found in these and other sites, often deeply buried, and 30 radiocarbon dates placed the occupations between 18,500 and 17,000 radiocarbon years ago. These finds led us to suggest an earlymore » origin of food production, with implications for the initial development of complex societies. Several barley seeds were analyzed by electron spin resonance spectroscopy to determine the maximal temperature to which they had been subjected before burial. Six barley seeds and three small pieces of wood charcoal were dated directly by using a tandem accelerator mass spectrometer.« less

Microflora distributions in paleosols: a method for calculating the validity of radiocarbon-dated surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahaney, W.C.; Boyer, M.G.

1986-08-01

Microflora (bacteria and fungi) distributions in several paleosols from Mount Kenya, East Africa, provide important information about contamination of buried soil horizons dated by radiocarbon. High counts of bacteria and fungi in buried soils provide evidence for contamination by plant root effects or ground water movement. Profiles with decreasing counts versus depth appear to produce internally consistent and accurate radiocarbon dates. Profiles with disjunct or bimodal distributions of microflora at various depths produce internally inconsistent chronological sequences of radiocarbon-dated buried surfaces. Preliminary results suggest that numbers up to 5 x 10/sup 2/ g/sup -1/ for bacteria in buried A horizonsmore » do not appear to affect the validity of /sup 14/C dates. Beyond this threshold value, contamination appears to produce younger dates, the difference between true age and /sup 14/C age increasing with the amount of microflora contamination.« less

Age estimation in forensic sciences: Application of combined aspartic acid racemization and radiocarbon analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alkass, K; Buchholz, B A; Ohtani, S

Age determination of unknown human bodies is important in the setting of a crime investigation or a mass disaster, since the age at death, birth date and year of death, as well as gender, can guide investigators to the correct identity among a large number of possible matches. Traditional morphological methods used by anthropologists to determine age are often imprecise, whereas chemical analysis of tooth dentin, such as aspartic acid racemization has shown reproducible and more precise results. In this paper we analyze teeth from Swedish individuals using both aspartic acid racemization and radiocarbon methodologies. The rationale behind using radiocarbonmore » analysis is that above-ground testing of nuclear weapons during the cold war (1955-1963) caused an extreme increase in global levels of carbon-14 ({sup 14}C) which have been carefully recorded over time. Forty-four teeth from 41 individuals were analyzed using aspartic acid racemization analysis of tooth crown dentin or radiocarbon analysis of enamel and ten of these were split and subjected to both radiocarbon and racemization analysis. Combined analysis showed that the two methods correlated well (R2=0.66, p < 0.05). Radiocarbon analysis showed an excellent precision with an overall absolute error of 0.6 {+-} 04 years. Aspartic acid racemization also showed a good precision with an overall absolute error of 5.4 {+-} 4.2 years. Whereas radiocarbon analysis gives an estimated year of birth, racemization analysis indicates the chronological age of the individual at the time of death. We show how these methods in combination can also assist in the estimation of date of death of an unidentified victim. This strategy can be of significant assistance in forensic casework involving dead victim identification.« less

Human-in-the-loop Control of Multi-agent Aerial Systems Under Intermittent Communication

DTIC Science & Technology

2015-06-08

Bogdan FAKULTET ELEKTROTEHNIKE I RACUNARS UNSKA 3 ZAGREB 10000 CROATIA EOARD GRANT #FA8655-13-1-3055 Report Date: June 2015...ELEKTROTEHNIKE I RACUNARS UNSKA 3 ZAGREB 10000 CROATIA 8. PERFORMING ORGANIZATION REPORT NUMBER N/A 9. SPONSORING/MONITORING AGENCY NAME...Laboratory for Robotics and Intelligent Control Systems Faculty of Electrical Engineering and Computing University of Zagreb PI:Prof.dr.sc. Stjepan Bogdan

Extension of the Southern Hemisphere Atmospheric Radiocarbon Curve, 2120-850 years BP: Results from Tasmanian Huon Pine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zimmerman, S R; P.Guilderson, T; Buckley, B M

2010-02-12

Decadal samples of dendrochronologically-dated pine (Lagorostrobos franklinii) from the Stanley River basin, Tasmania have been radiocarbon dated between 2120-850 yr BP. This data set overlaps and extends the current Southern Hemisphere record, which currently covers the period 110-995 yr BP. There is good agreement between the two records between 995-850 yr BP, between sample replicates and with consensus values for standards. As in the younger dataset, we find evidence for a distinct but variable offset between the southern hemisphere data and IntCal04; although this is likely due to real temporal variability in the interhemispheric offset, further work is planned tomore » rule out possible laboratory or sample preparation differences.« less

Radiocarbon dating of extinct fauna in the Americas recovered from tar pits

NASA Astrophysics Data System (ADS)

Jull, A. J. T.; Iturralde-Vinent, M.; O'Malley, J. M.; MacPhee, R. D. E.; McDonald, H. G.; Martin, P. S.; Moody, J.; Rincón, A.

2004-08-01

We have obtained radiocarbon dates by accelerator mass spectrometry on bones of extinct large mammals from tar pits. Results on some samples of Glyptodon and Holmesina (extinct large mammals similar to armadillos) yielded ages of >25 and >21 ka, respectively. We also studied the radiocarbon ages of three different samples of bones from the extinct Cuban ground sloth, Parocnus bownii, which yielded dates ranging from 4960 ± 280 to 11 880 ± 420 yr BP. In order to remove the tar component pretreat the samples sufficiently to obtain reliable dates, we cleaned the samples by Soxhlet extraction in benzene. Resulting samples of collagenous material were often small.

Application of Bomb Radiocarbon Chronologies to Shortfin Mako (Isurus oxyrinchus)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ardizzone, D; Cailliet, G M; Natanson, L J

performed and the number of samples for MIA analysis was insufficient for some months. Hence, unequivocal validation of shortfin mako age estimates has yet to be accomplished. Atmospheric testing of thermonuclear devices in the 1950s and 1960s effectively doubled the natural atmospheric radiocarbon ({sup 14}C). The elevated {sup 14}C levels were first recorded in 1957-58, with a peak around 1963. As a consequence, {sup 14}C entered the ocean through gas exchange with the atmosphere at the ocean surface and in terrestrial runoff. Despite variable oceanographic conditions, a worldwide rise of the bomb {sup 14}C signal entered the ocean mixed layer as dissolved inorganic carbon (DIC) in 1957-58. The large amounts of {sup 14}C released from the bomb tests produced a signature that can be followed through time, throughout the marine food web, and into deeper waters. The marked increase of radiocarbon levels was first measured in the DIC of seawater and in biogenic marine carbonates of hermatypic corals in Florida. Subsequently, this record was documented in corals from other regions and in the thallus of rhodoliths. The accumulation of radiocarbon in the hard parts of most marine organisms in the mixed layer (such as fish otoliths and bivalves) was synchronous with the coral time-series. This technique has been used to validate age estimates and longevity of numerous bony fishes to date, as well as to establish bomb radiocarbon chronologies from different oceans. In the first application of this technique to lamnoid sharks, validated annual band-pair deposition in vertebral growth bands for the porbeagle (Lamna nasus) aged up to 26 years. Radiocarbon values from samples obtained from 15 porbeagle caught in the western North Atlantic Ocean (some of which were known-age) produced a chronology similar in magnitude to the reference carbonate chronology for that region. The observed phase shift of about 3 years was attributed to different sources of carbon between vertebrae and those

Accreditation of medical laboratories in Croatia--experiences of the Institute of Clinical Chemistry, University Hospital "Merkur", Zagreb.

PubMed

Flegar-Mestrić, Zlata; Nazor, Aida; Perkov, Sonja; Surina, Branka; Kardum-Paro, Mirjana Mariana; Siftar, Zoran; Sikirica, Mirjana; Sokolić, Ivica; Ozvald, Ivan; Vidas, Zeljko

2010-03-01

Since 2003 when the international norm for implementation of quality management in medical laboratories (EN ISO 15189, Medical laboratories--Particular requirements for quality and competence) was established and accepted, accreditation has become practical, generally accepted method of quality management and confirmation of technical competence of medical laboratories in the whole world. This norm has been translated into Croatian and accepted by the Croatian Institute for Norms as Croatian norm. Accreditation is carried out on voluntary basis by the Croatian Accreditation Agency that has up to now accredited two clinical medical biochemical laboratories in the Republic of Croatia. Advantages of accredited laboratory lie in its documented management system, constant improvement and training, reliability of test results, establishing users' trust in laboratory services, test results comparability and interlaboratory (international) test results acceptance by adopting the concept of metrological traceability in laboratory medicine.

Radiocarbon dating casts doubt on the late chronology of the Middle to Upper Palaeolithic transition in southern Iberia.

PubMed

Wood, Rachel E; Barroso-Ruíz, Cecilio; Caparrós, Miguel; Jordá Pardo, Jesús F; Galván Santos, Bertila; Higham, Thomas F G

2013-02-19

It is commonly accepted that some of the latest dates for Neanderthal fossils and Mousterian industries are found south of the Ebro valley in Iberia at ca. 36 ka calBP (calibrated radiocarbon date ranges). In contrast, to the north of the valley the Mousterian disappears shortly before the Proto-Aurignacian appears at ca. 42 ka calBP. The latter is most likely produced by anatomically modern humans. However, two-thirds of dates from the south are radiocarbon dates, a technique that is particularly sensitive to carbon contaminants of a younger age that can be difficult to remove using routine pretreatment protocols. We have attempted to test the reliability of chronologies of 11 southern Iberian Middle and early Upper Paleolithic sites. Only two, Jarama VI and Zafarraya, were found to contain material that could be reliably dated. In both sites, Middle Paleolithic contexts were previously dated by radiocarbon to less than 42 ka calBP. Using ultrafiltration to purify faunal bone collagen before radiocarbon dating, we obtain ages at least 10 ka (14)C years older, close to or beyond the limit of the radiocarbon method for the Mousterian at Jarama VI and Neanderthal fossils at Zafarraya. Unless rigorous pretreatment protocols have been used, radiocarbon dates should be assumed to be inaccurate until proven otherwise in this region. Evidence for the late survival of Neanderthals in southern Iberia is limited to one possible site, Cueva Antón, and alternative models of human occupation of the region should be considered.

Radiocarbon dating casts doubt on the late chronology of the Middle to Upper Palaeolithic transition in southern Iberia

PubMed Central

Wood, Rachel E.; Barroso-Ruíz, Cecilio; Caparrós, Miguel; Jordá Pardo, Jesús F.; Galván Santos, Bertila; Higham, Thomas F. G.

2013-01-01

It is commonly accepted that some of the latest dates for Neanderthal fossils and Mousterian industries are found south of the Ebro valley in Iberia at ca. 36 ka calBP (calibrated radiocarbon date ranges). In contrast, to the north of the valley the Mousterian disappears shortly before the Proto-Aurignacian appears at ca. 42 ka calBP. The latter is most likely produced by anatomically modern humans. However, two-thirds of dates from the south are radiocarbon dates, a technique that is particularly sensitive to carbon contaminants of a younger age that can be difficult to remove using routine pretreatment protocols. We have attempted to test the reliability of chronologies of 11 southern Iberian Middle and early Upper Paleolithic sites. Only two, Jarama VI and Zafarraya, were found to contain material that could be reliably dated. In both sites, Middle Paleolithic contexts were previously dated by radiocarbon to less than 42 ka calBP. Using ultrafiltration to purify faunal bone collagen before radiocarbon dating, we obtain ages at least 10 ka 14C years older, close to or beyond the limit of the radiocarbon method for the Mousterian at Jarama VI and Neanderthal fossils at Zafarraya. Unless rigorous pretreatment protocols have been used, radiocarbon dates should be assumed to be inaccurate until proven otherwise in this region. Evidence for the late survival of Neanderthals in southern Iberia is limited to one possible site, Cueva Antón, and alternative models of human occupation of the region should be considered. PMID:23382220

A graphical method to evaluate predominant geochemical processes occurring in groundwater systems for radiocarbon dating

USGS Publications Warehouse

Han, Liang-Feng; Plummer, Niel; Aggarwal, Pradeep

2012-01-01

A graphical method is described for identifying geochemical reactions needed in the interpretation of radiocarbon age in groundwater systems. Graphs are constructed by plotting the measured 14C, δ13C, and concentration of dissolved inorganic carbon and are interpreted according to specific criteria to recognize water samples that are consistent with a wide range of processes, including geochemical reactions, carbon isotopic exchange, 14C decay, and mixing of waters. The graphs are used to provide a qualitative estimate of radiocarbon age, to deduce the hydrochemical complexity of a groundwater system, and to compare samples from different groundwater systems. Graphs of chemical and isotopic data from a series of previously-published groundwater studies are used to demonstrate the utility of the approach. Ultimately, the information derived from the graphs is used to improve geochemical models for adjustment of radiocarbon ages in groundwater systems.

AMS Radiocarbon Dating of Large Za Baobabs (Adansonia za) of Madagascar

PubMed Central

Patrut, Adrian; Patrut, Roxana T.; Danthu, Pascal; Leong Pock-Tsy, Jean-Michel; Rakosy, Laszlo; Lowy, Daniel A.; von Reden, Karl F.

2016-01-01

The article reports the radiocarbon investigation of Anzapalivoro, the largest za baobab (Adansonia za) specimen of Madagascar and of another za, namely the Big cistern baobab. Several wood samples collected from the large inner cavity and from the outer part/exterior of the tree were investigated by AMS (accelerator mass spectrometry) radiocarbon dating. For samples collected from the cavity walls, the age values increase with the distance into the wood up to a point of maximum age, after which the values decrease toward the outer part. This anomaly of age sequences indicates that the inner cavity of Anzapalivoro is a false cavity, practically an empty space between several fused stems disposed in a ring-shaped structure. The radiocarbon date of the oldest sample was 780 ± 30 bp, which corresponds to a calibrated age of around 735 yr. Dating results indicate that Anzapalivoro has a closed ring-shaped structure, which consists of 5 fused stems that close a false cavity. The oldest part of the biggest za baobab has a calculated age of 900 years. We also disclose results of the investigation of a second za baobab, the Big cistern baobab, which was hollowed out for water storage. This specimen, which consists of 4 fused stems, was found to be around 260 years old. PMID:26760300

[Radiocarbon dating of pollen and spores in wedge ice from Iamal and Kolyma].

PubMed

Vasil'chuk, A K

2004-01-01

Radiocarbon dating of pollen concentrate from late Pleistocene syngenetic wedge ice was carried out using acceleration mass spectrometry (AMS) in Seyakha and Bizon sections. Comparison of the obtained dating with palynological analysis and AMS radiocarbon dating previously obtained for other organic fractions of the same samples allowed us to evaluate accuracy of dating of different fractions. Quantitative tests for data evaluation were considered in terms of possible autochthonous or allochthonous accumulation of the material on the basis of pre-Pleistocene pollen content in these samples. Paleoecological information content of pollen spectra from late Pleistocene syngenetic wedge ice was evaluated.

Insights into soil carbon dynamics across climatic and geologic gradients from temporally-resolved radiocarbon measurements

NASA Astrophysics Data System (ADS)

van der Voort, T. S.; Hagedorn, F.; Mannu, U.; Walthert, L.; McIntyre, C.; Eglinton, T. I.

2016-12-01

Soil carbon constitutes the largest terrestrial reservoir of organic carbon, and therefore quantifying soil organic matter dynamics (carbon turnover, stocks and fluxes) across spatial gradients is essential for an understanding of the carbon cycle and the impacts of global change. In particular, links between soil carbon dynamics and different climatic and compositional factors remains poorly understood. Radiocarbon constitutes a powerful tool for unraveling soil carbon dynamics. Temporally-resolved radiocarbon measurements, which take advantage of "bomb-radiocarbon"-driven changes in atmospheric 14C, enable further constraints to be placed on C turnover times. These in turn can yield more precise flux estimates for both upper and deeper soil horizons. This project combines bulk radiocarbon measurements on a suite of soil profiles spanning strong climatic (MAT 1.3-9.2°C, MAP 600 to 2100 mm m-2y-1) and geologic gradients with a more in-depth approach for a subset of locations. For this subset, temporal and carbon-fraction specific radiocarbon data has been acquired for both topsoil and deeper soils. These well-studied sites are part of the Long-Term Forest Ecosystem Research (LWF) program of the Swiss Federal Institute for Forest, Snow and Landscape research (WSL). Resulting temporally-resolved turnover estimates are coupled to carbon stocks, fluxes across this wide range of forest ecosystems and are examined in the context of environmental drivers (temperature, precipitation, primary production and soil moisture) as well as composition (sand, silt and clay content). Statistical analysis on the region-scale - correlating radiocarbon signature with climatic variables such as temperature, precipitation, primary production and elevation - indicates that composition rather than climate is a key driver of ­­Δ14C signatures. Estimates of carbon turnover, stocks and fluxes derived from temporally-resolved measurements highlight the pivotal role of soil moisture as a

Zagreb Conference on English Contrastive Projects, 7-9 December 1970. Papers and Discussion. Studies 4. The Yugoslav Serbo-Croatian-English Contrastive Project.

ERIC Educational Resources Information Center

Filipovic, Rudolf, Ed.

The fourth volume in this series contains the papers presented at the Zagreb Conference on English Contrastive Projects. They are: "Recent Center Activities in Contrastive Linguistics," by William Nemser; "The Yugoslav Serbo-Croatian-English Contrastive Project So Far," by Rudolf Filipovic; "The Poznan Polish-English Contrastive Project," by Jacek…

Development of a TOF SIMS setup at the Zagreb heavy ion microbeam facility

NASA Astrophysics Data System (ADS)

Tadić, Tonči; Bogdanović Radović, Iva; Siketić, Zdravko; Cosic, Donny Domagoj; Skukan, Natko; Jakšić, Milko; Matsuo, Jiro

2014-08-01

We describe a new Time-of-flight Secondary Ion Mass Spectrometry (TOF SIMS) setup for MeV SIMS application, which is constructed and installed at the heavy ion microbeam facility at the Ruđer Bošković Institute in Zagreb. The TOF-SIMS setup is developed for high sensitivity molecular imaging using a heavy ion microbeam that focuses ion beams (from C to I) with sub-micron resolution. Dedicated pulse processing electronics for MeV SIMS application have been developed, enabling microbeam-scanning control, incoming ion microbeam pulsing and molecular mapping. The first results showing measured MeV SIMS spectra as well as molecular maps for samples of interest are presented and discussed.

Immunogenicity, safety and antibody persistence of a purified vero cell cultured rabies vaccine (Speeda) administered by the Zagreb regimen or Essen regimen in post-exposure subjects.

PubMed

Shi, Nianmin; Zhang, Yibin; Zheng, Huizhen; Zhu, Zhenggang; Wang, Dingming; Li, Sihai; Li, Yuhua; Yang, Liqing; Zhang, Junnan; Bai, Yunhua; Lu, Qiang; Zhang, Zheng; Luo, Fengji; Yu, Chun; Li, Li

2017-06-03

To compare the safety, immunogenicity and long-term effect of a purified vero cell cultured rabies vaccine in post-exposure subjects following 2 intramuscular regimens, Zagreb or Essen regimen. Serum samples were collected before vaccination and on days 7, 14, 42, 180 and 365 post vaccination. Solicited adverse events were recorded for 7 d following each vaccine dose, and unsolicited adverse events throughout the entire study period. This study was registered with ClinicalTrials.gov (NCT01821911 and NCT01827917). No serious adverse events were reported. Although Zagreb regimen had a higher incidence of adverse reactions than Essen regimen at the first and second injection, the incidence was similar at the third and fourth injection between these 2 groups as well. At day 42, 100% subjects developed adequate rabies virus neutralizing antibody concentrations (≥ 0.5IU/ml) for both regimens. At days 180 and 365, the antibody level decreased dramatically, however, the percentage of subjects with adequate antibody concentrations still remained high (above 75% and 50% respectively). None of confirmed rabies virus exposured subjects had rabies one year later, and percentage of subjects with adequate antibody concentrations reached 100% at days 14 and 42. Rabies post-exposure prophylaxis vaccination with PVRV following a Zagreb regimen had a similar safety, immunogenicity and long-term effect to the Essen regimen in China.

Immunogenicity, safety and antibody persistence of a purified vero cell cultured rabies vaccine (Speeda) administered by the Zagreb regimen or Essen regimen in post-exposure subjects

PubMed Central

Shi, Nianmin; Zhang, Yibin; Zheng, Huizhen; Zhu, Zhenggang; Wang, Dingming; Li, Sihai; Li, Yuhua; Yang, Liqing; Zhang, Junnan; Bai, Yunhua; Lu, Qiang; Zhang, Zheng; Luo, Fengji; Yu, Chun; Li, Li

2017-01-01

ABSTRACT Aim: To compare the safety, immunogenicity and long-term effect of a purified vero cell cultured rabies vaccine in post-exposure subjects following 2 intramuscular regimens, Zagreb or Essen regimen. Methods: Serum samples were collected before vaccination and on days 7, 14, 42, 180 and 365 post vaccination. Solicited adverse events were recorded for 7 d following each vaccine dose, and unsolicited adverse events throughout the entire study period. This study was registered with ClinicalTrials.gov (NCT01821911 and NCT01827917). Results: No serious adverse events were reported. Although Zagreb regimen had a higher incidence of adverse reactions than Essen regimen at the first and second injection, the incidence was similar at the third and fourth injection between these 2 groups as well. At day 42, 100% subjects developed adequate rabies virus neutralizing antibody concentrations (≥ 0.5IU/ml) for both regimens. At days 180 and 365, the antibody level decreased dramatically, however, the percentage of subjects with adequate antibody concentrations still remained high (above 75% and 50% respectively). None of confirmed rabies virus exposured subjects had rabies one year later, and percentage of subjects with adequate antibody concentrations reached 100% at days 14 and 42. Conclusions: Rabies post-exposure prophylaxis vaccination with PVRV following a Zagreb regimen had a similar safety, immunogenicity and long-term effect to the Essen regimen in China. PMID:28121231

Measurements and modeling of contemporary radiocarbon in the stratosphere

NASA Astrophysics Data System (ADS)

Kanu, A. M.; Comfort, L. L.; Guilderson, T. P.; Cameron-Smith, P. J.; Bergmann, D. J.; Atlas, E. L.; Schauffler, S.; Boering, K. A.

2016-02-01

Measurements of the 14C content of carbon dioxide in air collected by high-altitude balloon flights in 2003-2005 reveal the contemporary radiocarbon distribution in the northern midlatitude stratosphere, four decades after the Limited Test Ban Treaty restricted atmospheric testing of nuclear weapons. Comparisons with results from a 3-D chemical-transport model show that the 14CO2 distribution is now largely governed by the altitude/latitude dependence of the natural cosmogenic production rate, stratospheric transport, and propagation into the stratosphere of the decreasing radiocarbon trend in tropospheric CO2 due to fossil fuel combustion. From the observed correlation of 14CO2 with N2O mixing ratios, an annual global mean net flux of 14CO2 to the troposphere of 1.6(±0.4) × 1017‰ mol CO2 yr-1 and a global production rate of 2.2(±0.6) × 1026 atoms 14C yr-1 are empirically derived. The results also indicate that contemporary 14CO2 observations provide highly sensitive diagnostics for stratospheric transport and residence times in models.

Vertebral bomb radiocarbon suggests extreme longevity in white sharks.

PubMed

Hamady, Li Ling; Natanson, Lisa J; Skomal, Gregory B; Thorrold, Simon R

2014-01-01

Conservation and management efforts for white sharks (Carcharodon carcharias) remain hampered by a lack of basic demographic information including age and growth rates. Sharks are typically aged by counting growth bands sequentially deposited in their vertebrae, but the assumption of annual deposition of these band pairs requires testing. We compared radiocarbon (Δ(14)C) values in vertebrae from four female and four male white sharks from the northwestern Atlantic Ocean (NWA) with reference chronologies documenting the marine uptake of (14)C produced by atmospheric testing of thermonuclear devices to generate the first radiocarbon age estimates for adult white sharks. Age estimates were up to 40 years old for the largest female (fork length [FL]: 526 cm) and 73 years old for the largest male (FL: 493 cm). Our results dramatically extend the maximum age and longevity of white sharks compared to earlier studies, hint at possible sexual dimorphism in growth rates, and raise concerns that white shark populations are considerably more sensitive to human-induced mortality than previously thought.

Vertebral Bomb Radiocarbon Suggests Extreme Longevity in White Sharks

PubMed Central

Hamady, Li Ling; Natanson, Lisa J.; Skomal, Gregory B.; Thorrold, Simon R.

2014-01-01

Conservation and management efforts for white sharks (Carcharodon carcharias) remain hampered by a lack of basic demographic information including age and growth rates. Sharks are typically aged by counting growth bands sequentially deposited in their vertebrae, but the assumption of annual deposition of these band pairs requires testing. We compared radiocarbon (Δ14C) values in vertebrae from four female and four male white sharks from the northwestern Atlantic Ocean (NWA) with reference chronologies documenting the marine uptake of 14C produced by atmospheric testing of thermonuclear devices to generate the first radiocarbon age estimates for adult white sharks. Age estimates were up to 40 years old for the largest female (fork length [FL]: 526 cm) and 73 years old for the largest male (FL: 493 cm). Our results dramatically extend the maximum age and longevity of white sharks compared to earlier studies, hint at possible sexual dimorphism in growth rates, and raise concerns that white shark populations are considerably more sensitive to human-induced mortality than previously thought. PMID:24416189

Spatial and temporal distribution of platinum, palladium and rhodium in Zagreb air.

PubMed

Rinkovec, Jasmina; Pehnec, Gordana; Godec, Ranka; Davila, Silvije; Bešlić, Ivan

2018-09-15

Platinum (Pt), palladium (Pd) and rhodium (Rh) are most widely used in the production of automotive catalytic converters that serve to reduce toxic emissions from motor vehicles. The aim of this study was to quantitatively determine the levels of platinum, palladium and rhodium in the PM 10 and PM 2.5 fraction of airborne particle matter and find their spatial and temporal distribution at different polluted areas of the city of Zagreb, Croatia. The method used in this paper included weekly sampling of airborne particle matter on quartz filters, microwave digestion in acid under high pressure and temperature, and analysis by inductively coupled plasma mass spectrometry (ICP MS). The results have shown that the highest mean values at all three sampling stations (North, Center, South) were obtained for palladium (3.856 pg m -3 , 5.396 pg m -3 , 5.600 pg m -3 ) and the lowest for rhodium (0.444 pg m -3 , 0.643 pg m -3 , 0.750 pg m -3 ). The average mass concentrations of platinum group elements (PGE) in PM 10 increased for all three elements in the direction North < Center < South which had to do with the traffic load nearby the monitoring stations. The ratio of measured mass concentrations to all measuring stations was similar to platinum, palladium and rhodium content in automotive catalytic converters. Factor analysis grouped platinum, palladium and rhodium at all of the monitoring stations, and their relation to other metals together with the aforementioned results indicate that their main source of pollution is traffic or precisely automotive catalytic converters. At all three of the monitoring sites, higher values were measured during the colder part of the year. The results of measuring platinum, palladium and rhodium levels in the city of Zagreb are the first results of their kind for this area and will provide insights into the contribution of catalytic converters to the presence of these elements in the environment. Copyright �

Soil organic matter stability as indicated by compound-specific radiocarbon analyses

NASA Astrophysics Data System (ADS)

van der Voort, Tessa Sophia; Zell, Claudia; Hagedorn, Frank; McIntyre, Cameron; Eglinton, Timothy Ian

2017-04-01

Carbon storage in soils is increasingly recognized as a key ecosystem function, and molecular-level analyses could be a valuable potential indicator of this storage potential. In this framework, radiocarbon constitutes a powerful tool for unraveling soil carbon dynamics on both decadal as well as centennial and millennial timescales. In this study, we look at the radiocarbon signature of specific compounds (fatty acids and n-alkanes) in two forested ecosystems (temperate and pre-alpine) with the aim of attaining a better understanding of soil organic carbon stability on a molecular level. Radiocarbon dating of the fatty acids and n-alkanes has been coupled to abundance data of these compounds and additionally lignin phenols. We hypothesize that potentially, these long-chain apolar compounds could be a representative indicator of the mineral-bound soil organic carbon pool. These well-studied sites are part of the Long-Term Forest Ecosystem Research (LWF) program of the Swiss Federal Institute for Forest, Snow and Landscape research (WSL). Therefore, a wide suite of ancillary climatic and textural data is available for these sites. Initial results show a wide range of ages in the specific compounds which constitute a much larger range than the ages indicated by the density fractions done on the same samples. Overall, this study explores the use of molecular-level indicators to study soil organic matter dynamics, which could help assess the overall potential vulnerability of soil carbon in various ecosystems.

Performance report for the low energy compact radiocarbon accelerator mass spectrometer at Uppsala University

NASA Astrophysics Data System (ADS)

Salehpour, M.; Håkansson, K.; Possnert, G.; Wacker, L.; Synal, H.-A.

2016-03-01

A range of ion beam analysis activities are ongoing at Uppsala University, including Accelerator Mass Spectrometry (AMS). Various isotopes are used for AMS but the isotope with the widest variety of applications is radiocarbon. Up until recently, only the 5 MV Pelletron tandem accelerator had been used at our site for radiocarbon AMS, ordinarily using 12 MeV 14,13,12C3+ ions. Recently a new radiocarbon AMS system, the Green-MICADAS, developed at the ion physics group at ETH Zurich, was installed. The system has a number of outstanding features which will be described. The system operates at a terminal voltage of 175 kV and uses helium stripper gas, extracting singly charged carbon ions. The low- and high energy mass spectrometers in the system are stigmatic dipole permanent magnets (0.42 and 0.97 T) requiring no electrical power nor cooling water. The system measures both the 14C/12C and the 13C/12C ratios on-line. Performance of the system is presented for both standard mg samples as well as μg-sized samples.

Radiocarbon constraints on the glacial ocean circulation and its impact on atmospheric CO2

PubMed Central

Skinner, L. C.; Primeau, F.; Freeman, E.; de la Fuente, M.; Goodwin, P. A.; Gottschalk, J.; Huang, E.; McCave, I. N.; Noble, T. L.; Scrivner, A. E.

2017-01-01

While the ocean’s large-scale overturning circulation is thought to have been significantly different under the climatic conditions of the Last Glacial Maximum (LGM), the exact nature of the glacial circulation and its implications for global carbon cycling continue to be debated. Here we use a global array of ocean–atmosphere radiocarbon disequilibrium estimates to demonstrate a ∼689±53 14C-yr increase in the average residence time of carbon in the deep ocean at the LGM. A predominantly southern-sourced abyssal overturning limb that was more isolated from its shallower northern counterparts is interpreted to have extended from the Southern Ocean, producing a widespread radiocarbon age maximum at mid-depths and depriving the deep ocean of a fast escape route for accumulating respired carbon. While the exact magnitude of the resulting carbon cycle impacts remains to be confirmed, the radiocarbon data suggest an increase in the efficiency of the biological carbon pump that could have accounted for as much as half of the glacial–interglacial CO2 change. PMID:28703126

Radiocarbon constraints on the glacial ocean circulation and its impact on atmospheric CO2

NASA Astrophysics Data System (ADS)

Skinner, L. C.; Primeau, F.; Freeman, E.; de La Fuente, M.; Goodwin, P. A.; Gottschalk, J.; Huang, E.; McCave, I. N.; Noble, T. L.; Scrivner, A. E.

2017-07-01

While the ocean's large-scale overturning circulation is thought to have been significantly different under the climatic conditions of the Last Glacial Maximum (LGM), the exact nature of the glacial circulation and its implications for global carbon cycling continue to be debated. Here we use a global array of ocean-atmosphere radiocarbon disequilibrium estimates to demonstrate a ~689+/-53 14C-yr increase in the average residence time of carbon in the deep ocean at the LGM. A predominantly southern-sourced abyssal overturning limb that was more isolated from its shallower northern counterparts is interpreted to have extended from the Southern Ocean, producing a widespread radiocarbon age maximum at mid-depths and depriving the deep ocean of a fast escape route for accumulating respired carbon. While the exact magnitude of the resulting carbon cycle impacts remains to be confirmed, the radiocarbon data suggest an increase in the efficiency of the biological carbon pump that could have accounted for as much as half of the glacial-interglacial CO2 change.

[Historical Review of Cesarean Section at King's Maternity Hospital and Midwifery School Zagreb 1908-1918].

PubMed

Habek, D; Kruhak, V

2016-04-01

This article presents a historical review of the performance of 23 cesarean sections at the King’s Maternity Hospital and Midwifery School in Zagreb during the 1908-1918 period. Following prenatal screening by midwives and doctors in the hospital, deliveries in high risk pregnant women were performed at maternity hospitals, not at home. The most common indication for cesarean section was narrowed pelvis in 65.2% of women, while postpartum febrile condition was the most common complication in the puerperium. Maternal mortality due to sepsis after the procedure was 8.69% and overall perinatal mortality was 36.3% (stillbirths and early neonatal deaths).

AMS radiocarbon investigation of the African baobab: Searching for the oldest tree

NASA Astrophysics Data System (ADS)

Patrut, Adrian; von Reden, Karl F.; Mayne, Diana H.; Lowy, Daniel A.; Patrut, Roxana T.

2013-01-01

The Glencoe baobab, a very large specimen from South Africa, split twice in 2009. Several wood samples were collected from the eastern cavity, from the outer part of the main section and also from the largest broken segment which was connected to this section. These wood samples were processed and investigated by AMS radiocarbon dating. The radiocarbon date of the oldest sample was found to be 1838 ± 21 BP, which corresponds to a calibrated age of 1835 ± 40 years. Thus, the Glencoe baobab becomes the oldest dated baobab and also the oldest angiosperm tree with accurate dating results. The distribution of dating results revealed that the Glencoe baobab is a multi-generation tree, with several standing or collapsed and partially fused stems, showing different ages.

Morphology and Density Structure of Post-CME

DTIC Science & Technology

2010-06-26

Zagreb , Croatia 2 INAF-Arcetri Observatory, Firenze, Italy 3 Faculty of Science, Geophysical Department, Croatia 4 Naval Research Laboratory, Washington...AND ADDRESS(ES) Hvar Observatory,,Faculty of Geodes, Zagreb , Croatia, , 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME

BIOGENIC CONTRIBUTION TO PM-2.5 AMBIENT AEROSOL FROM RADIOCARBON MEASUREMENTS

EPA Science Inventory

Knowledge of the relative contributions of biogenic versus anthropogenic sources to ambient aerosol is of great interest in the formulation of strategies to achieve nationally mandated air quality standards. Radiocarbon (Carbon-14) measurements provide a means to quantify the ...

Grass material as process standard for compound-specific radiocarbon analysis

NASA Astrophysics Data System (ADS)

Cisneros-Dozal, Malu; Xu, Xiaomei; Bryant, Charlotte; Pearson, Emma; Dungait, Jennifer

2015-04-01

Compound-specific radiocarbon analysis (CSRA) is a powerful tool to study the carbon cycle and/or as a dating technique in paleoclimate reconstructions. The radiocarbon value of individual compounds can provide insight into turnover times, organic matter sources and in specific cases can be used to establish chronologies when traditional dating materials (e.g. macrofossils, pollen, charcoal) are not available. The isolation of compounds (or group of compounds) from parent material (e.g. soil, plant) for radiocarbon analysis can, however, introduce carbon contamination through chemical separation steps and preparative capillary gas chromatography (PCGC). In addition, the compounds of interest are often in low abundance which amplifies the contamination effect. The extraneous carbon can be of modern 14C age and/or 14C -free and its amount and 14C value must be determined for a given system/isolation procedure in order to report accurate 14C values. This can be achieved by using adequate standard materials but, by contrast with traditional radiocarbon dating, there are not established reference standards for CSRA work, in part because the type of standard material depends on the compounds of interest and the isolation procedure. Here we evaluate the use of n-alkanes extracted from single-year growth grass as modern process standard material for CSRA using PCGC isolation. The grass material has a known 14C value of 1.224 ± 0.006 fraction modern (FM) and the individual n-alkanes are expected to have a similar 14C value. In order to correct for the addition of extraneous carbon during PCGC isolation of the n-alkanes, we used commercially available compounds of modern 14C content and 14C -free (adipic acid, FM= 0.0015 ± 0.0001 and docosane, FM=1.059 ± 0.003) to evaluate our PCGC procedure. The corrected 14C values of the isolated n-alkanes extracted from the modern grass are within one sigma of the grass bulk 14C value for n-C29 and within two sigma for n-C23-C27, C31

Investigating the Impact of Past and Future CO2 Emissions on the Distribution of Radiocarbon in the Ocean

NASA Astrophysics Data System (ADS)

Khatiwala, S.; Payne, S.; Graven, H. D.; Heimbach, P.

2015-12-01

The ocean is a significant sink for carbon dioxide from fossil fuel burning, absorbing roughly a third of human CO2 emitted over the industrial period. This has implications not only for climate but also for the chemical and isotopic composition of the ocean. Human activities have increased the ocean radiocarbon content through nuclear bomb tests in the 1950s-60s, which released a large amount of radiocarbon (14C) into the atmosphere, but fossil fuel emissions are decreasing the radiocarbon content through the release of 14C-depleted CO2. Here, we use the ECCO-v4 ocean state estimate to examine the changing nature of the air-sea flux of radiocarbon and its spatial distribution in the ocean in response to past and future CO2 emissions, the latter taken from the the Representative Concentration Pathway (RCP) database used in IPCC simulations. In line with previous studies we find that the large air-sea gradient of 14C induced by nuclear bomb testing led to rapid accumulation of radiocarbon in the surface ocean. Surface fluxes of 14C have considerably weakened over the past several decades and in some areas 14C is being returned to the atmosphere. As fossil fuel emissions continue to reduce the atmospheric 14C/C ratio (Δ14C), in most RCP scenarios the total ocean 14C inventory starts decreasing by 2030. With strong emissions, the Δ14C of surface waters is driven to increasingly negative values and in RCP 8.5 by 2100 much of the surface ocean has apparent radiocarbon ages in excess of 2000 years, with subtropical gyres more depleted in 14C than the Southern Ocean. Surface waters become significantly more negative in Δ14C than underlying waters. As a result, turning conventional tracer oceanography on its head, recently ventilated waters are characterized by more negative Δ14C values. Similar patterns can be expected for CFCs in the ocean as atmospheric concentrations decrease over the next several decades. Our results have a number of implications, notably for

A coherent high-precision radiocarbon chronology for the Late-glacial sequence at Sluggan Bog, Co. Antrim, Northern Ireland

NASA Astrophysics Data System (ADS)

Lowe, J. J.; Walker, M. J. C.; Scott, E. M.; Harkness, D. D.; Bryant, C. L.; Davies, S. M.

2004-02-01

Seventy-five radiocarbon dates are presented from Sluggan Bog in Co. Antrim, Northern Ireland. The Holocene peats are underlain by Late-glacial sediments, which also appear to have accumulated largely in a mire environment. The radiocarbon dates, from the Late-glacial and early Holocene part of the profile, were obtained from the humic and humin fractions of the sedimentary matrix, and from plant macrofossils. The last-named were dated by AMS and the sediment samples by radiometric (beta counting) methods. Age-depth models for the three dating series show a very high level of agreement between the two fractions and the macrofossils. No statistically significant difference is found between the beta counting and AMS results. Three tephras were located in the profile, the uppermost of which is in a stratigraphical position suggestive of the Vedde Ash, but the geochemical and radiocarbon evidence do not support this interpretation. The lower ashes are in the correct stratigraphical position for the Laacher See and Borrobol tephras, attributions substantiated by the radiocarbon evidence, but not by the geochemical data. The Sluggan sequence has generated one of the most internally consistent radiocarbon chronologies for any Late-glacial site in the British Isles, and it is suggested that in future more effort should be devoted to the search for, and analysis of, Late-glacial mire sequences, rather than the limnic records that have formed the principal focus of Late-glacial investigations hitherto. Copyright

Drivers of soil organic matter vulnerability to climate change, Part II: RothC modelling of carbon dynamics including radiocarbon data

NASA Astrophysics Data System (ADS)

Studer, Mirjam S.; Abiven, Samuel; González Domínguez, Beatriz R.; Hagedorn, Frank; Reisser, Moritz; Walthert, Lorenz; Zimmermann, Stephan; Niklaus, Pascal A.

2016-04-01

It is still largely unknown what drives the vulnerability of soil organic carbon (SOC) stocks to climate change, i.e. the likelihood of a soil to loose its SOC along with the change in environmental conditions. Our objective is to assess the SOC vulnerability of Swiss forest soils and identify its potential drivers: climate (temperature, soil moisture), soil (clay content, pH) and landscape (slope, aspect) properties. Fifty-four sites were selected for balanced spatial and driver magnitudes distribution. We measured the SOC characteristics (content and radiocarbon) and studied the C decomposition by laboratory soil incubations (details in Part I, abstract by B. González Domínguez). In order to assess the current SOC pool distribution and its radiocarbon signatures, we extended the Rothamsted Carbon (RothC) model with radiocarbon (14C) isotope modelling (RothCiso). The RothC model distinguishes four active SOC pools, decomposable and resistant plant material, microbial biomass and humified organic matter, and an inert SOC pool (Jenkinson 1990). The active pools are decomposed and mineralized to CO2 by first order kinetics. The RothCiso assigns all pools a 14C signature, based on the atmospheric 14C concentrations of the past century (plant C inputs) and their turnover. Currently we constrain the model with 14C signatures measured on the 54 fresh and their corresponding archived bulk soil samples, taken 12-24 years before. We were able to reproduce the measured radiocarbon concentrations of the SOC with the RothCiso and first results indicate, that the assumption of an inert SOC pool, that is radiocarbon dead, is not appropriate. In a second step we will compare the SOC mean residence time assessed by the two methodological approaches - incubation (C efflux based) and modelling (C stock based) - and relate it to the environmental drivers mentioned above. With the combination of the two methodological approaches and 14C analysis we hope to gain more insights into

Changes in Soil Carbon Turnover after Five Years of Bioenergy Cropping Systems from a Long-Term Incubation Experiment and Radiocarbon Measurements.

NASA Astrophysics Data System (ADS)

Szymanski, L. M.; Sanford, G. R.; Heckman, K. A.; Jackson, R. D.; Marin-Spiotta, E.

2016-12-01

In the face of climate change, the global production of bioenergy crops has increased in response to policies calling for non-fossil energy sources as a means to mitigate rising atmospheric carbon (C) concentrations. To provide overall C sequestration benefits, identifying biomass crops that can maintain or enhance soil resources is desirable for sustainable bioenergy production. The objective of our study was to compare the effects of four bioenergy cropping systems on SOM dynamics in two agricultural soils: Mollisols at the University of Wisconsin Agricultural Research Station in Arlington, Wisconsin and Alfisols at Kellogg Biological Station in Hickory Corners, Michigan, USA. We used fresh soils collected in 2013 and archived soils collected in 2008 to measure differences among biofuel crops after 5 years of management. Using a 365-day laboratory soil incubation and radiocarbon measurements of bulk soil and respired C, we separated soils into three SOM pools and determined their corresponding turnover times. Total soil C respired from surface soils increased in the order: mixed species perennials > monoculture perennials > monoculture annuals. More C was associated with the active fraction in the sandy loam Alfisol and with the slow-cycling fraction in the silt loam Mollisol. Radiocarbon content of respired CO2 did not differ between corn and switchgrass, but did differ between 2008 and 2013. The respiration of more radiocarbon-depleted C after 5 years of cultivation may be due to an initial flux of young C following tillage in 2008 or to depletion of labile plant inputs with continued harvest. All bioenergy cropping systems lost soil C after 5 years. Monoculture perennial switchgrass systems did not provide significant C sequestration benefits, as expected, compared to monoculture annual corn systems. Bioenergy crop land-use change affects soil C dynamics, with implications for assessing C costs associated with biofuel production.

RADIOCARBON MEASUREMENTS ON PM 2.5 AMBIENT AEROSOL FROM NASHVILLE, TN

EPA Science Inventory

Radiocarbon (Carbon-14) measurements provide an estimate of the fraction of carbon in a sample that is biogenic. The methodology has been extensively used in past wintertime studies to quantify the contribution of wood smoke to ambient aerosol. In summertime such measurements...

Measurements and modeling of contemporary radiocarbon in the stratosphere

DOE PAGES

Kanu, A. M.; Comfort, L. L.; Guilderson, T. P.; ...

2016-01-29

Measurements of the 14C content of carbon dioxide in air collected by high-altitude balloon flights in 2003–2005 reveal the contemporary radiocarbon distribution in the northern midlatitude stratosphere, four decades after the Limited Test Ban Treaty restricted atmospheric testing of nuclear weapons. Comparisons with results from a 3-D chemical-transport model show that the 14CO 2 distribution is now largely governed by the altitude/latitude dependence of the natural cosmogenic production rate, stratospheric transport, and propagation into the stratosphere of the decreasing radiocarbon trend in tropospheric CO 2 due to fossil fuel combustion. From the observed correlation of 14CO 2 with N 2Omore » mixing ratios, an annual global mean net flux of 14CO 2 to the troposphere of 1.6(±0.4) × 10 17‰ mol CO 2 yr –1 and a global production rate of 2.2(±0.6) × 10 26 atoms 14C yr –1 are empirically derived. Furthermore, the results also indicate that contemporary 14CO 2 observations provide highly sensitive diagnostics for stratospheric transport and residence times in models.« less

A Chronology of Late-Glacial and Holocene Advances of Quelccaya Ice Cap, Peru, Based on 10Be and Radiocarbon Dating

NASA Astrophysics Data System (ADS)

Kelly, M. A.; Lowell, T. V.; Schaefer, J. M.

2007-12-01

The Quelccaya Ice Cap region in the southeastern Peruvian Andes (~13-14°S latitude) is a key location for the development of late-glacial and Holocene terrestrial paleoclimate records in the tropics. We present a chronology of past extents of Quelccaya Ice Cap based on ~thirty internally consistent 10Be dates of boulders on moraines and bedrock as well as twenty radiocarbon dates of organic material associated with moraines. Based on results from both dating methods, we suggest that significant advances of Quelccaya Ice Cap occurred during late-glacial time, at ~12,700-11,400 yr BP, and during Late Holocene time ~400-300 yr BP. Radiocarbon dating of organic material associated with moraines provides maximum and minimum ages for ice advances and recessions, respectively, thus providing an independent check on 10Be dates of boulders on moraines. The opportunity to use both 10Be and radiocarbon dating makes the Quelccaya Ice Cap region a potentially important low-latitude calibration site for production rates of cosmogenic nuclides. Our radiocarbon chronology provides a tighter constraint on maximum ages of late-glacial and Late Holocene ice advances. Upcoming field research will obtain organic material for radiocarbon dating to improve minimum age constrains for late-glacial and Late Holocene ice recessions.

Reconciling radiocarbon and ice core timescales over the Holocene - Cosmogenic radionuclides as synchronization tools

NASA Astrophysics Data System (ADS)

Muscheler, R.; Adolphi, F.; Mekhaldi, F.

2015-12-01

The atmospheric production rates of cosmogenic radionuclides, such as 14C and 10Be, vary globally due to external processes, namely the solar and geomagnetic modulation of the galactic cosmic ray flux as well as solar proton events. This signature is recorded in various archives such as ice cores (10Be) and tree-rings (14C). Hence, cosmogenic radionuclides offer a means to continuously assess timescale differences between two of the most widely used timescales in paleoclimatology - the radiocarbon and the ice core timescales. Short lived solar proton events additionally provide distinct marker horizons that allow synchronization of discrete horizons at annual precision. We will present a cosmogenic radionuclide based synchronization of the Greenland ice core timescale (GICC05, Svensson et al., 2008) and the radiocarbon timescale (IntCal13, Reimer et al., 2013) over the Holocene. This synchronization allows radiocarbon dated and ice core paleoclimate records to be compared on a common timescale at down to sub-decadal precision. We will compare these results to independent discrete isochrones obtained from tephrochronology and solar proton events. In addition, we will discuss implications for the accuracy and uncertainty estimates of GICC05 over the Holocene. Reimer, P. J., Bard, E., Bayliss, A., Beck, J. W., Blackwell, P. G., Bronk Ramsey, C., Buck, C. E., Cheng, H., Edwards, R. L., Friedrich, M., Grootes, P. M., Guilderson, T. P., Haflidason, H., Hajdas, I., Hatté, C., Heaton, T. J., Hoffmann, D. L., Hogg, A. G., Hughen, K. A., Kaiser, K. F., Kromer, B., Manning, S. W., Niu, M., Reimer, R. W., Richards, D. A., Scott, E. M., Southon, J. R., Staff, R. A., Turney, C. S. M., and van der Plicht, J.: IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0-50,000 Years cal BP, Radiocarbon, 55, 1869-1887, 10.2458/azu_js_rc.55.16947, 2013. Svensson, A., Andersen, K. K., Bigler, M., Clausen, H. B., Dahl-Jensen, D., Davies, S. M., Johnsen, S. J., Muscheler, R., Parrenin

[Frequencies of airborne moulds in Zagreb].

PubMed

Segvić, Maja; Pepeljnjak, Stjepan

2004-06-01

Airborne fungi are sometimes associated with several respiratory diseases and allergies. This paper describes a study of qualitative and quantitative variations in the occurrence of airborne moulds in Zagreb area on three locations: centre of the city (C), Pharmaceutical Botanical Garden "Fran Kusan" (BG) and the mountain Medvednica (M) during autumn, winter, spring and summer 2002-03. Lower concentrations of airborne moulds were found in all three locations in autumn (up to 76.88 CFU/m3) and winter (31.46 CFU/m3), with significantly higher levels in C and BG than in M (P<0.001). In spring and summer, these concentrations were much higher in all sampling sites and were significantly higher in C (160.00 CFU/m3) and BG (134.00 CFU/m3) in spring than in M (90.07 CFU/m3) (P<0.001). In summer, significantly higher concentration was found in C (237.5 CFU/m3) than in BG (186.50 CFU/m3) (P<0.01), while concentrations in C and M (216.70 CFU/m3) were similar. Airspora belonging to 29 fungal genera were identified, and allergologicaly significant moulds, Cladosporium (up to 79.5%) and Alternaria (up to 59.4%) dominated in all sampling sites. Penicillium, Fusarium and Aspergillus were also constant fungal entities (43.0-70.5%), but in much lower concentrations than Cladosporium and Alternaria. Airsporas of Cladosporium and Alternaria were more frequent in spring and summer in all locations, with significantly higher concentrations in C and BG (P<0.05). The risk from allergies increases with higher airspora concentrations in spring and summer due to an increase in Cladosporium and Alternaria.

Radiocarbon Production by Thunderstorms

NASA Astrophysics Data System (ADS)

Babich, L. P.

2017-11-01

In view of the neutron flux enhancements observed in thunderstorms, a contribution of thunderstorm neutrons to atmospheric radiocarbon (isotope 614C) production is analyzed in connection with the archaeometry. Herein, estimates of neutron fluence per lightning electromagnetic pulse in regions with severe thunderstorm activity, at which a local rate of the 614C production is comparable to the observed rates, are shown to be consistent with the measured magnitudes of thunderstorm neutron fluence. At present, available observations of atmospheric neutron and parent gamma ray flashes correlated with thunderstorms do not allow making final conclusions about thunderstorm contributions to 614C production. For this, numerous studies of high-energy phenomena in thunderstorms are required, especially in the tropical belt where the thunderstorm activity is especially severe and where the 614C production by galactic cosmic rays is almost independent of the solar activity disturbing the Earth's magnetic field shielding the Earth from cosmic rays.

Radiocarbon dating of terrestrial carbonates

USGS Publications Warehouse

Pigati, Jeffrey S.; Rink, W. Jack; Thompson, Jeroen

2014-01-01

Terrestrial carbonates encompass a wide range of materials that potentially could be used for radiocarbon (14C) dating. Biogenic carbonates, including shells and tests of terrestrial and aquatic gastropods, bivalves, ostracodes, and foraminifera, are preserved in a variety of late Quaternary deposits and may be suitable for 14C dating. Primary calcareous deposits (marls, tufa, speleothems) and secondary carbonates (rhizoliths, fracture fill, soil carbonate) may also be targeted for dating when conditions are favorable. This chapter discusses issues that are commonly encountered in 14C dating of terrestrial carbonates, including isotopic disequilibrium and open-system behavior, as well as methods used to determine the reliability of ages derived from these materials. Recent methodological advancements that may improve the accuracy and precision of 14C ages of terrestrial carbonates are also highlighted.

Collection of radiocarbon dates on the mammoths ( Mammuthus primigenius) and other genera of Wrangel Island, northeast Siberia, Russia

NASA Astrophysics Data System (ADS)

Vartanyan, Sergey L.; Arslanov, Khikmat A.; Karhu, Juha A.; Possnert, Göran; Sulerzhitsky, Leopold D.

2008-07-01

We present and discuss a full list of radiocarbon dates for woolly mammoth and other species of the Mammoth fauna available from Wrangel Island, northeast Siberia, Russia. Most of the radiocarbon dates are published here for the first time. Of the124 radiocarbon dates on mammoth bone, 106 fall between 3700 and 9000 yr ago. We believe these dates bracket the period of mammoth isolation on Wrangel Island and their ultimate extinction, which we attribute to natural causes. The absence of dates between 9-12 ka probably indicates a period when mammoths were absent from Wrangel Island. Long bone dimensions of Holocene mammoths from Wrangel Island indicate that these animals were comparable in size to those on the mainland; although they were not large animals, neither can they be classified as dwarfs. Occurrence of mammoth Holocene refugia on the mainland is suggested. Based on other species of the Mammoth fauna that have also been radiocarbon on Wrangel Island, including horse, bison, musk ox and woolly rhinoceros, it appears that the mammoth was the only species of that fauna that inhabited Wrangel Island in the mid-Holocene.

The Role of Discussion Boards in Facilitating Communities of Inquiry: A Case of ICT and Sociology Courses at Zagreb School of Economics and Management

ERIC Educational Resources Information Center

Aleksic-Maslac, Karmela; Magzan, Masha; Juric, Visnja

2009-01-01

The study focuses on the use of technology to design an electronic learning community for students. The importance of social experience in education and social participation through communication is examined through discussion boards of two different freshmen courses offered at Zagreb School of Economics and Management (ZSEM). Effectiveness and…

Coral radiocarbon constraints on the source of the Indonesian throughflow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, M.D.; Schrag, D.P.; Kashgarian, M.

1997-06-01

Radiocarbon variability in {ital Porites} spp. corals from Guam and the Makassar Strait (Indonesian Seaway) was used to identify the source waters contributing to the Indonesian throughflow. Time series with bimonthly resolution were constructed using accelerator mass spectrometry. The seasonal variability ranges from 15 to 60{per_thousand}, with large interannual variability. {Delta}{sup 14}C values from Indonesia and Guam have a nearly identical range. Annual mean {Delta}{sup 14}C values from Indonesia are 50 to 60{per_thousand} higher than in corals from Canton in the South Equatorial Current [{ital Druffel}, 1987]. These observations support a year-round North Pacific source for the Indonesian throughflow andmore » imply negligible contribution by South Equatorial Current water. The large seasonality in {Delta}{sup 14}C values from both sites emphasizes the dynamic behavior of radiocarbon in the surface ocean and suggests that {Delta}{sup 14}C time series of similar resolution can help constrain seasonal and interannual changes in ocean circulation in the Pacific over the last several decades.{copyright} 1997 American Geophysical Union« less

Radiocarbon analysis of halophilic microbial lipids from an Australian salt lake

NASA Astrophysics Data System (ADS)

Bray, P. Sargent; Jones, Claudia M.; Fallon, Stewart J.; Brocks, Jochen J.; George, Simon C.

2012-01-01

Assigning accurate dates to hypersaline sediments opens important terrestrial records of local and regional paleoecologies and paleoclimatology. However, as of yet no conventional method of dating hypersaline systems has been widely adopted. Biomarker, mineralogical, and radiocarbon analyses of sediments and organic extracts from a shallow (13 cm) core from a hypersaline playa, Lake Tyrrell, southeastern Australia, produce a coherent age-depth curve beginning with modern microbial mats and extending to ~ 7500 cal yr BP. These analyses are furthermore used to identify and constrain the timing of the most recent change in hydrological regime at Lake Tyrrell, a shift from a clay deposit to the precipitation of evaporitic sands occurring at some time between ~ 4500 and 7000 yr. These analyses show the potential for widespread dating of hypersaline systems integrating the biomarker approach, reinforce the value of the radiocarbon content of biomarkers in understanding the flow of carbon in modern ecologies, and validate the temporal dimension of data provided by biomarkers when dating late Quaternary sediments.

On the Origin of the Solar Moreton Wave of 2006 December 6

DTIC Science & Technology

2010-11-01

Flight Center. Huntsville. AL 35812. USA 9 National Solar Observatory. Tucson, AZ 85719, USA 10 Faculty of Geodesy, University of Zagreb , Hvar...Observatory, HR 10000 Zagreb , Croatia 1’ Space Vehicles Directorate, Air Force Research Laboratory, Kirtland AFB, NM 87117, US A Received 2010 April 7

Protective efficacy of standard Edmonston-Zagreb measles vaccination in infants aged 4.5 months: interim analysis of a randomised clinical trial.

PubMed

Martins, Cesário L; Garly, May-Lill; Balé, Carlito; Rodrigues, Amabelia; Ravn, Henrik; Whittle, Hilton C; Lisse, Ida M; Aaby, Peter

2008-07-24

To examine the protective efficacy of measles vaccination in infants in a low income country before 9 months of age. Randomised clinical trial. 1333 infants aged 4.5 months: 441 in treatment group and 892 in control group. Urban area in Guinea-Bissau. Measles vaccination using standard titre Edmonston-Zagreb vaccine at 4.5 months of age. Vaccine efficacy against measles infection, admission to hospital for measles, and measles mortality before standard vaccination at 9 months of age. 28% of the children tested at 4.5 months of age had protective levels of maternal antibodies against measles at enrolment. After early vaccination against measles 92% had measles antibodies at 9 months of age. A measles outbreak offered a unique situation for testing the efficacy of early measles vaccination. During the outbreak, 96 children developed measles; 19% of unvaccinated children had measles before 9 months of age. The monthly incidence of measles among the 441 children enrolled in the treatment arm was 0.7% and among the 892 enrolled in the control arm was 3.1%. Early vaccination with the Edmonston-Zagreb measles vaccine prevented infection; vaccine efficacy for children with serologically confirmed measles and definite clinical measles was 94% (95% confidence interval 77% to 99%), for admissions to hospital for measles was 100% (46% to 100%), and for measles mortality was 100% (-42% to 100%). The number needed to treat to prevent one case of measles between ages 4.5 months and 9 months during the epidemic was 7.2 (6.8 to 9.2). The treatment group tended to have lower overall mortality (mortality rate ratio 0.18, 0.02 to 1.36) although this was not significant. In low income countries, maternal antibody levels against measles may be low and severe outbreaks of measles can occur in infants before the recommended age of vaccination at 9 months. Outbreaks of measles may be curtailed by measles vaccination using the Edmonston-Zagreb vaccine as early as 4.5 months of age. TRIAL

[Clinical and epidemiologic characteristics of hemorrhagic fever with renal syndrome in patients treated at the Dr. Fran Mihaljević Clinic for Infectious Diseases in Zagreb].

PubMed

Puljiz, Ivan; Kuzman, Ilija; Turcinov, Drago; Markotić, Alemka; Celjuska, Elvira

2003-01-01

The aim of the study was to examine and analyze the main epidemiologic and clinical data of 94 patients with hemorrhagic fever with renal syndrome (HFRS) hospitalized at the University Hospital for Infectious Diseases in Zagreb during the HFRS outbreak in Croatia in 2002. A total of 110 patients with clinical diagnosis HFRS were treated at the University Hospital for Infectious Diseases in Zagreb. In 110 of HFRS suspected patients, the clinical diagnosis was verified serologically in 94 patients and they were included in the retrospective study. In 93 patients the diagnosis was confirmed by enzyme-linked immunosorbent assay (ELISA), and in one patient by indirect immunofluorescence assay (IFA). Results were analyzed by the use of descriptive statistics. Puumala (PUU) virus infection was verified in 80 (85.1%), Dobrava (DOB) infection in 8 (8.5%) and cross-reactive antibodies to both PUU and DOB viruses in 5 (5.3%) HFRS patients. In one patient who was confirmed by IFA the hantavirus serotype causing HFRS could not be determined. The localities of the presumed HFRS patient exposure to hantaviruses were mostly in the Zagreb area. Most patients were aged 21-50 (83.0%) and male (76.6%). The majority of HFRS cases occurred between May and August (75.5%). A high proportion of HFRS cases were found in the general population from Zagreb and its surroundings (78.7%). The majority of patients were hospitalized in the febrile stage of the disease (70.2%). The main symptoms were: fever (100%), headache (88.3%) and backache (87.2%). Oliguria was recorded in 56.4% and, anuria in 7.5% of patients, however, only three (3.2%) patients required hemodialysis. Six patients developed hemorrhagic manifestations, especially petechiae on the skin and mucosa. One patient in the convalescent stage had subarachnoidal bleeding. Six patients had pathologic electroencephalogram (EEG) findings and two developed epileptic seizures. Lumbar puncture was performed in 12 patients without inflammatory

Atmospheric radiocarbon as a Southern Ocean wind proxy over the last 1000 years

NASA Astrophysics Data System (ADS)

Rodgers, K. B.; Mikaloff Fletcher, S.; Galbraith, E.; Sarmiento, J. L.; Gnanadesikan, A.; Slater, R. D.; Naegler, T.

2009-04-01

Measurements of radiocarbon in tree rings over the last 1000 years indicate that there was a pre-industrial latitudinal gradient of atmospheric radiocarbon of 3.9-4.5 per mail and that this gradient had temporal variability of order 6 per mil. Here we test the idea that the mean gradient as well as variability in he gradient is dominated by the strength of the winds over the Southern Ocean. This is done using an ocean model and an atmospheric transport model. The ocean model is used to derive fluxes of 12CO2 and 14CO2 at the sea surface, and these fluxes are used as a lower boundary condition for the transport model. For the mean state, strong winds in the Southern Ocean drive significant upwelling of radiocarbon-depleted Circumpolar Deep Water (CDW), leading to a net flux of 14CO2 relative to 12CO2 into the ocean. This serves to maintain a hemispheric gradient in pre-anthropogenic atmospheric delta-c14. For perturbations, increased/decreased Southern Ocean winds drive increased/decreased uptake of 14CO2 relative to 12CO2, thus increasing/decreasing the hemispheric gradient in atmospheric delta-c14. The tree ring data is interpreted to reveal a decrease in the strength of the Southern Ocean winds at the transition between the Little Ice Age and the Medieval Warm Period.

Acceptance Tests for AMS Radiocarbon Measurements at iThemba LABS, Gauteng, South Africa

NASA Astrophysics Data System (ADS)

Mbele, Vela L.; Mullins, Simon M.; Winkler, Stephan R.; Woodborne, Stephan

The accelerator mass spectrometer was commissioned recently at the iThemba LABS 6 MV tandem accelerator. Improvements in the vacuum system, requiring procurement of cryo-pumps and the reducing the tank pressure of the N2 + CO2 insulation gas mixture below the level used for IBA measurements, were necessary. This resulted in the reduction of the nitrogen background and improved the resolution of 14C from 14N background in the ionisation chamber. The nitrogen was leaking to the stripping canal because of inadequate sealing. The analysing magnet was scaled to detect C3+ ions, at 3 MV terminal potential. The first sensible spectra allowed for the pin-pointing of many persistent issues. This resulted in measurements with a precision better than 1 pMC, and current blank levels correspond to 12 half-lives of 14C or ∼68000 years. The radiocarbon sample preparation laboratory has reached production status. A brief outlook of the work towards the implementation of the measurement and chemical preparation protocols for radionuclides 10Be and 26Al is also summarised in the conclusion

Dissemination of the Project's Findings. National Seminar (14th, Zagreb, Yugoslavia, July 5-7, 1989). The CDCC's Project No. 8: "Innovation in Primary Education."

ERIC Educational Resources Information Center

Galton, Maurice

A 3-day conference was convened in Zagreb, Yugoslavia for the purpose of disseminating results of the Council of Europe's Council for Cultural Cooperation's (CDCC) Project 8, Innovation in Primary Education (IPE). Changes in theoretical approaches to and organizational practices of primary education in Yugoslavia were discussed. A total of 61…

Exploring global carbon turnover and radiocarbon cycling in terrestrial biosphere models

NASA Astrophysics Data System (ADS)

Graven, H. D.; Warren, H.

2017-12-01

The uptake of carbon into terrestrial ecosystems through net primary productivity (NPP) and the turnover of that carbon through various pathways are the fundamental drivers of changing carbon stocks on land, in addition to human-induced and natural disturbances. Terrestrial biosphere models use different formulations for carbon uptake and release, resulting in a range of values in NPP of 40-70 PgC/yr and biomass turnover times of about 25-40 years for the preindustrial period in current-generation models from CMIP5. Biases in carbon uptake and turnover impact simulated carbon uptake and storage in the historical period and later in the century under changing climate and CO2 concentration, however evaluating global-scale NPP and carbon turnover is challenging. Scaling up of plot-scale measurements involves uncertainty due to the large heterogeneity across ecosystems and biomass types, some of which are not well-observed. We are developing the modelling of radiocarbon in terrestrial biosphere models, with a particular focus on decadal 14C dynamics after the nuclear weapons testing in the 1950s-60s, including the impact of carbon flux trends and variability on 14C cycling. We use an estimate of the total inventory of excess 14C in the biosphere constructed by Naegler and Levin (2009) using a 14C budget approach incorporating estimates of total 14C produced by the weapons tests and atmospheric and oceanic 14C observations. By simulating radiocarbon in simple biosphere box models using carbon fluxes from the CMIP5 models, we find that carbon turnover is too rapid in many of the simple models - the models appear to take up too much 14C and release it too quickly. Therefore many CMIP5 models may also simulate carbon turnover that is too rapid. A caveat is that the simple box models we use may not adequately represent carbon dynamics in the full-scale models. Explicit simulation of radiocarbon in terrestrial biosphere models would allow more robust evaluation of biosphere

Zagreb Amblyopia Preschool Screening Study: near and distance visual acuity testing increase the diagnostic accuracy of screening for amblyopia.

PubMed

Bušić, Mladen; Bjeloš, Mirjana; Petrovečki, Mladen; Kuzmanović Elabjer, Biljana; Bosnar, Damir; Ramić, Senad; Miletić, Daliborka; Andrijašević, Lidija; Kondža Krstonijević, Edita; Jakovljević, Vid; Bišćan Tvrdi, Ana; Predović, Jurica; Kokot, Antonio; Bišćan, Filip; Kovačević Ljubić, Mirna; Motušić Aras, Ranka

2016-02-01

To present and evaluate a new screening protocol for amblyopia in preschool children. Zagreb Amblyopia Preschool Screening (ZAPS) study protocol performed screening for amblyopia by near and distance visual acuity (VA) testing of 15 648 children aged 48-54 months attending kindergartens in the City of Zagreb County between September 2011 and June 2014 using Lea Symbols in lines test. If VA in either eye was >0.1 logMAR, the child was re-tested, if failed at re-test, the child was referred to comprehensive eye examination at the Eye Clinic. 78.04% of children passed the screening test. Estimated prevalence of amblyopia was 8.08%. Testability, sensitivity, and specificity of the ZAPS study protocol were 99.19%, 100.00%, and 96.68% respectively. The ZAPS study used the most discriminative VA test with optotypes in line as they do not underestimate amblyopia. The estimated prevalence of amblyopia was considerably higher than reported elsewhere. To the best of our knowledge, the ZAPS study protocol reached the highest sensitivity and specificity when evaluating diagnostic accuracy of VA tests for screening. The pass level defined at ≤0.1 logMAR for 4-year-old children, using Lea Symbols in lines missed no amblyopia cases, advocating that both near and distance VA testing should be performed when screening for amblyopia.

Zagreb Amblyopia Preschool Screening Study: near and distance visual acuity testing increase the diagnostic accuracy of screening for amblyopia

PubMed Central

Bušić, Mladen; Bjeloš, Mirjana; Petrovečki, Mladen; Kuzmanović Elabjer, Biljana; Bosnar, Damir; Ramić, Senad; Miletić, Daliborka; Andrijašević, Lidija; Kondža Krstonijević, Edita; Jakovljević, Vid; Bišćan Tvrdi, Ana; Predović, Jurica; Kokot, Antonio; Bišćan, Filip; Kovačević Ljubić, Mirna; Motušić Aras, Ranka

2016-01-01

Aim To present and evaluate a new screening protocol for amblyopia in preschool children. Methods Zagreb Amblyopia Preschool Screening (ZAPS) study protocol performed screening for amblyopia by near and distance visual acuity (VA) testing of 15 648 children aged 48-54 months attending kindergartens in the City of Zagreb County between September 2011 and June 2014 using Lea Symbols in lines test. If VA in either eye was >0.1 logMAR, the child was re-tested, if failed at re-test, the child was referred to comprehensive eye examination at the Eye Clinic. Results 78.04% of children passed the screening test. Estimated prevalence of amblyopia was 8.08%. Testability, sensitivity, and specificity of the ZAPS study protocol were 99.19%, 100.00%, and 96.68% respectively. Conclusion The ZAPS study used the most discriminative VA test with optotypes in lines as they do not underestimate amblyopia. The estimated prevalence of amblyopia was considerably higher than reported elsewhere. To the best of our knowledge, the ZAPS study protocol reached the highest sensitivity and specificity when evaluating diagnostic accuracy of VA tests for screening. The pass level defined at ≤0.1 logMAR for 4-year-old children, using Lea Symbols in lines missed no amblyopia cases, advocating that both near and distance VA testing should be performed when screening for amblyopia. PMID:26935612

SUFFICIENT IODINE INTAKE IN SCHOOLCHILDREN FROM THE ZAGREB AREA: ASSESSMENT WITH DRIED BLOD SPOT THYROGLOBULIN AS A NEW FUNCTIONAL BIOMARKER FOR IODINE DEFICIENCY.

PubMed

Jukić, Tomislav; Zimmermann, Michael Bruce; Granić, Roko; Prpić, Marin; Krilić, Drazena; Juresa, Vesna; Katalenić, Marijan; Kusić, Zvonko

2015-12-01

Current methods for assessment of iodine intake in a population comprise measurements of urinary iodine concentration (UIC), thyroid volume by ultrasound (US-Tvol), and newborn TSH. Serum or dried blood spot thyroglobulin (DBS-Tg) is a new promising functional iodine status biomarker in children. In 1996, a new act on universal salt iodination was introduced in Croatia with 25 mg of potassium iodideper kg of salt. In 2002, Croatia finally reached iodine sufficiency. However, in 2009, median UIC in 101 schoolchildren from Zagreb, the capital of Croatia, was 288 µg/L, posing to be excessive. The aim of the study was to assess iodine intake in schoolchildren from the Zagreb area and to evaluate the value of DBS-Tg in schoolchildren as a new functional biomarker of iodine deficiency (and iodine excess). The study was part of a large international study in 6- to 12-year-old children supported by UNICEF, the Swiss Federal Institute of Technology (ETH Zurich) and the International Council for the Control of Iodine Deficiency Disorders (ICCIDD). According to international study results, the median cut-off Tg < 13 µg/L and/or < 3% Tg values > 40 µg/L indicate iodine sufficiency. The study included 159 schoolchildren (median age 9.1 ± 1.4 years) from Zagreb and a nearby small town of Jastrebarsko with measurements of UIC, US-Tvol, DBS-Tg, T4, TSH and iodine content in salt from households of schoolchildren (KI/kg of salt). Overall median UIC was 205 µg/L (range 1-505 µg/L). Thyroid volumes in schoolchildren measured by US were within the normal range according to reference values. Median DBS-Tg in schoolchildren was 12.1 µg/L with 3% of Tg values > 40 µg/L. High Tg values were in the UIC range < 50 µg/L and > 300 µg/L (U-shaped curve of Tg plotted against UIC). All children were euthyroid with geometric mean TSH 0.7 ± 0.3 mU/L and arithmetic mean T4 62 ± 12.5 nmol/L. The mean KI content per kg of salt was 24.9 ± 3.1 mg/kg (range 19-36 mg/kg). Study results

AMS radiocarbon dating of very large Grandidier's baobabs (Adansonia grandidieri)

NASA Astrophysics Data System (ADS)

Patrut, Adrian; von Reden, Karl F.; Danthu, Pascal; Leong Pock-Tsy, Jean-Michel; Rakosy, Laszlo; Patrut, Roxana T.; Lowy, Daniel A.; Margineanu, Dragos

2015-10-01

The article reports the AMS radiocarbon investigation of the two largest known Adansonia grandidieri specimens. The two baobabs, which are named Tsitakakoike and Pregnant baobab, are located in Southwestern Madagascar, near Andombiro. A third specimen from this area, the House baobab, was also investigated. According to measurements, Tsitakakoike is the biggest individual above ground level of all Adansonia species. The House baobab was selected for its exposed structure, which is identical to the closed ring-shaped structure with false cavities identified by us in large and old Adansonia digitata specimens. According to our research, Tsitakakoike and the Pregnant baobab have multi-stemmed cylindrical trunks which are mainly hollow; the two very large baobabs also possess a ring-shaped structure. The radiocarbon dates of the oldest wood samples collected from the large trunks were 1274 ± 20 BP for Tsitakakoike and 930 ± 20 BP for the Pregnant baobab. According to their original positions and to the architectures of the two A. grandidieri, the ages of Tsitakakoike and Pregnant baobab would be between 1300 and 1500 years. Therefore, A. grandidieri becomes the third Adansonia species with individuals that can live over 1000 years, according to accurate dating results.

Radiocarbon dating and compositional analysis of pre-Columbian human bones

NASA Astrophysics Data System (ADS)

Andrade, E.; Solís, C.; Canto, C. E.; de Lucio, O. G.; Chavez, E.; Rocha, M. F.; Villanueva, O.; Torreblanca, C. A.

2014-08-01

Analysis of ancient human bones found in "El Cóporo", an archaeological site in Guanajuato, Mexico; were performed using a multi techniques scheme: 14C radiocarbon dating, IBA (Ion Beam Analysis), SEM-EDS (Scanning Electron Microscope Energy Dispersive X-ray Spectroscopy). We measured the elemental composition of the bones, especially some with a superficial black pigmentation. Soil samples collected from the burial place were also analyzed. The 14C dating was performed with a new High Voltage Europe 1 MV Tandentron Accelerator Mass Spectrometer (AMS) recently installed in the IFUNAM (Instituto de Física, Universidad Nacional Autónoma de México). The radiocarbon dating allowed us to determine the date of death of the individual in a period between the year 890 and 975 AD, which is consistent with the late period of the Cóporo civilization. The element sample analysis of bones with the surface black pigmentation show higher levels of Fe, Mn and Ba compared when bone's black surface was mechanically removed. These three elements were found in soil samples from the skeleton burial place. These results indicate more likely that the bone black coloration is due to a postmortem alteration occurring in the burial environment.

Synthetic Constraint of Ecosystem C Models Using Radiocarbon and Net Primary Production (NPP) in New Zealand Grazing Land

NASA Astrophysics Data System (ADS)

Baisden, W. T.

2011-12-01

Time-series radiocarbon measurements have substantial ability to constrain the size and residence time of the soil C pools commonly represented in ecosystem models. Radiocarbon remains unique in the ability to constrain the large stabilized C pool with decadal residence times. Radiocarbon also contributes usefully to constraining the size and turnover rate of the passive pool, but typically struggles to constrain pools with residence times less than a few years. Overall, the number of pools and associated turnover rates that can be constrained depends upon the number of time-series samples available, the appropriateness of chemical or physical fractions to isolate unequivocal pools, and the utility of additional C flux data to provide additional constraints. In New Zealand pasture soils, we demonstrate the ability to constrain decadal turnover times with in a few years for the stabilized pool and reasonably constrain the passive fraction. Good constraint is obtained with two time-series samples spaced 10 or more years apart after 1970. Three or more time-series samples further improve the level of constraint. Work within this context shows that a two-pool model does explain soil radiocarbon data for the most detailed profiles available (11 time-series samples), and identifies clear and consistent differences in rates of C turnover and passive fraction in Andisols vs Non-Andisols. Furthermore, samples from multiple horizons can commonly be combined, yielding consistent residence times and passive fraction estimates that are stable with, or increase with, depth in different sites. Radiocarbon generally fails to quantify rapid C turnover, however. Given that the strength of radiocarbon is estimating the size and turnover of the stabilized (decadal) and passive (millennial) pools, the magnitude of fast cycling pool(s) can be estimated by subtracting the radiocarbon-based estimates of turnover within stabilized and passive pools from total estimates of NPP. In grazing

Can medical students recognize depression? A survey at the Zagreb School of Medicine.

PubMed

Kuzman, Martina Rojnic; Bosnjak, Dina; Vokal, Petra; Kuharic, Josip; Brkic, Ivana; Kuzman, Tomislav; Dujmovic, Josip

2014-06-01

The objective of this study was to investigate medical students' knowledge and attitudes towards depression. Students attending their final year at Zagreb School of Medicine completed a set of standardized questionnaires, including attitudes towards psychiatric medication, attitudes towards depression, and personality inventory. In total, 199 students completed the questionnaire (response rate 77 %). Most medical students were only partially able to correctly identify major symptoms of depression, but did suggest referral to mental health specialists as the most appropriate course of action. They recognized social and biological causes of depression. Degree of correct identification of symptoms of depression correlated positively with non-stigmatizing attitudes towards depression and negatively with stigmatizing attitudes towards depression. Students' attitudes toward depression may influence their recognition of symptoms of depression. Incorporation of these findings in development of undergraduate medical curricula may improve students' recognition of depression.

A study on the quality of outpatient prescription of psychopharmaceuticals in the City of Zagreb 2006-2009.

PubMed

Zivković, Kresimir; Zelić-Kerep, Ana; Stimac, Danijela; Ozić, Sanja; Zivković, Nikica

2014-06-01

The lack of Croatian studies which could determine the justifiability of excessive psychopharmaceutical utilization was an encouragement to conduct this research. Furthermore, regarding the conduction of this study, it would be possible to determine whether the trend of drug utilization has increased, decreased or perhaps stabilized. The data on the outpatient utilization of psycholeptics and psychoanaleptics were collected from all Zagreb pharmacies, 2006-2009. Based on the collected data for all N05 and N06 groups of drugs, the defined daily doses (DDD) and DDD per thousand inhabitants per day (DDD/TID) have been calculated using the Anatomical-Therapeutic-Chemical classification (ATC) for 2006, 2007, 2008 and 2009. To indicate the quality of drug prescription the Drug Utilization 90% (DU 90%) method was used. Moreover, in order to determine a more precise quality of individual drug group prescriptions, the indicators have been calculated by determining the proportion of the total utilization of individual therapeutic and pharmacological therapeutic subgroups in DDD/TID a day. The utilization of anxiolytics (N05B) accounts for most of the psycholeptic utilization in the City of Zagreb throughout the entire study period. In the study period, the utilization of antidepressants has slightly increased, by 10.5%, taking the first and the last years of the period into account. In 2006, 5 benzodiazepines and the hypnotic zolpidem, as well as 5 selective serotonin reuptake inhibitors (SSRIs) and 1 third generation antipsychotic (olanzapin) were found in the DU 90% segment. In 2009, the DU 90% segment also comprised 5 benzodiazepines and the hypnotic zolpidem, as well as 6 SSRIs and 1 third generation antipsychotic (olanzapin). In the City of Zagreb, a general insight into the quality of psychopharmaceutical prescriptions indicates stability in comparison to earlier studies. The ratio index of the first generation antipsychotic utilization, compared to the third

Radiocarbon dating with annual-resolution of subfossil trees from the Younger Dryas event in the southern French Alps

NASA Astrophysics Data System (ADS)

Capano, Manuela; Miramont, Cécile; Guibal, Frédéric; Kromer, Bernd; Tuna, Thibaut; Fagault, Yoann; Bard, Edouard

2017-04-01

Tree rings are an important archive for the calibration of radiocarbon data. The younger part of the IntCal curve is based essentially on tree-ring chronologies, absolutely dated by dendrochronological analysis. For the Northern Hemisphere (NH), a gap still exists between the absolutely dated sequences and a floating chronology. Based on the Southern Hemisphere (SH) tree-ring chronologies a link has been previously proposed (Reimer et al. 2013, Radiocarbon; see also update in Hogg et al. 2016, Radiocarbon). By measuring radiocarbon at annual resolution in French subfossil pines (Pinus sylvestris L.) we propose to improve the connection between the absolute chronology and the floating chronology. Several subfossil pines have been found in the Southern French Alps; they were buried by flood deposits, allowing their preservation. Some trees discovered in the Barbier riverbed were dated to the Younger Dryas periods by previous decadal radiocarbon measurements, performed in Heidelberg and Mannheim. The trees selected for our new study are Barb12 and Barb17 (analyzed sequences of 163 and 152 rings, respectively). These sequences were sampled at annual resolution when permitted by the ring width. As a first step, every third ring was pretreated for radiocarbon analysis. These samples were sliced in small pieces and pretreated by using the ABA-B method before being combusted, graphitized with the AGE system and measured with AixMICADAS (Bard et al. 2015, Nucl. Instr. Meth. B). From the comparison with the kauri sequence, the Barb12-17 sequence can be dated from about 12835 to 12606 cal. BP. It can also be used to calculate the interhemispheric gradient (IHG) over the overlapping period. In order to reduce the inter-annual variability, the Barb12-17 record was smoothed, grouped and averaged over the same decades as in the Kauri record. On the basis of twenty values, a mean IHG value of ca. 60 years was calculated. Quantification of the IHG around 50 yr is particularly

Study of a metallurgical site in Tuscany (Italy) by radiocarbon dating

NASA Astrophysics Data System (ADS)

Cartocci, A.; Fedi, M. E.; Taccetti, F.; Benvenuti, M.; Chiarantini, L.; Guideri, S.

2007-06-01

Tuscany represents one of the most important ancient mining districts of Italy. Metalworking activities have been present in the area since ancient times and several mining centres have been active in the region since the Etruscan period. Two of the more notable mining locations are the island of Elba and the towns of Populonia and Massa Marittima. In order to reconstruct the development of metallurgical techniques in the past, a multi-disciplinary approach is required, involving both archaeological study and archaeometric analysis of the sites of interest. One of the most complex problems is establishing the chronological history of metallurgical exploitation in ancient sites: archaeological remains are sometimes incomplete and the stratigraphy of archaeological horizons might have been deeply altered. Thus, direct dating of metallurgical slags and other remains of mining and metalworking activities using radiocarbon measurements is particularly useful for developing site chronologies. Charcoal samples from a recent excavation in Populonia were dated by AMS radiocarbon in order to reconstruct the chronological evolution of ancient metallurgical production; results reported here are consistent with archaeological observations.

Insights into soil carbon dynamics across climatic and geologic gradients from time-series and fraction-specific radiocarbon analysis

NASA Astrophysics Data System (ADS)

van der Voort, Tessa Sophia; Hagedorn, Frank; Zell, Claudia; McIntyre, Cameron; Eglinton, Tim

2016-04-01

Understanding the interaction between soil organic matter (SOM) and climatic, geologic and ecological factors is essential for the understanding of potential susceptibility and vulnerability to climate and land use change. Radiocarbon constitutes a powerful tool for unraveling SOM dynamics and is increasingly used in studies of carbon turnover. The complex and inherently heterogeneous nature of SOM renders it challenging to assess the processes that govern SOM stability by solely looking at the bulk signature on a plot-scale level. This project combines bulk radiocarbon measurements on a regional-scale spanning wide climatic and geologic gradients with a more in-depth approach for a subset of locations. For this subset, time-series and carbon pool-specific radiocarbon data has been acquired for both topsoil and deeper soils. These well-studied sites are part of the Long-Term Forest Ecosystem Research (LWF) program of the Swiss Federal Institute for Forest, Snow and Landscape research (WSL). Statistical analysis was performed to examine relationships of radiocarbon signatures with variables such as temperature, precipitation and elevation. Bomb-curve modeling was applied determine carbon turnover using time-series data. Results indicate that (1) there is no significant correlation between Δ14C signature and environmental conditions except a weak positive correlation with mean annual temperature, (2) vertical gradients in Δ14C signatures in surface and deeper soils are highly similar despite covering disparate soil-types and climatic systems, and (3) radiocarbon signatures vary significantly between time-series samples and carbon pools. Overall, this study provides a uniquely comprehensive dataset that allows for a better understanding of links between carbon dynamics and environmental settings, as well as for pool-specific and long-term trends in carbon (de)stabilization.

Revised direct radiocarbon dating of the Vindija G1 Upper Paleolithic Neandertals.

PubMed

Higham, Tom; Ramsey, Christopher Bronk; Karavanić, Ivor; Smith, Fred H; Trinkaus, Erik

2006-01-17

The 1998/1999 direct dating of two Neandertal specimens from level G(1) of Vindija Cave in Croatia to approximately 28,000 and approximately 29,000 radiocarbon ((14)C) years ago has led to interpretations concerning the late survival of Neandertals in south-central Europe, patterns of interaction between Neandertals and in-dispersing early modern humans in Europe, and complex biocultural scenarios for the earlier phases of the Upper Paleolithic. Given improvements, particularly in sample pretreatment techniques for bone radiocarbon samples, especially ultrafiltration of collagen samples, these Vindija G(1) Neandertal fossils are redated to approximately 32,000-33,000 (14)C years ago and possibly earlier. These results and the recent redating of a number of purportedly old modern human skeletal remains in Europe to younger time periods highlight the importance of fine chronological control when studying this biocultural time period and the tenuous nature of monolithic scenarios for the establishment of modern humans and earlier phases of the Upper Paleolithic in Europe.

Optical Measurement of Radiocarbon below Unity Fraction Modern by Linear Absorption Spectroscopy.

PubMed

Fleisher, Adam J; Long, David A; Liu, Qingnan; Gameson, Lyn; Hodges, Joseph T

2017-09-21

High-precision measurements of radiocarbon ( 14 C) near or below a fraction modern 14 C of 1 (F 14 C ≤ 1) are challenging and costly. An accurate, ultrasensitive linear absorption approach to detecting 14 C would provide a simple and robust benchtop alternative to off-site accelerator mass spectrometry facilities. Here we report the quantitative measurement of 14 C in gas-phase samples of CO 2 with F 14 C < 1 using cavity ring-down spectroscopy in the linear absorption regime. Repeated analysis of CO 2 derived from the combustion of either biogenic or petrogenic sources revealed a robust ability to differentiate samples with F 14 C < 1. With a combined uncertainty of 14 C/ 12 C = 130 fmol/mol (F 14 C = 0.11), initial performance of the calibration-free instrument is sufficient to investigate a variety of applications in radiocarbon measurement science including the study of biofuels and bioplastics, illicitly traded specimens, bomb dating, and atmospheric transport.

Dating of palaeomagnetic secular variation in Swedish varved lake sediments using radiocarbon wiggle-matching

NASA Astrophysics Data System (ADS)

Mellström, Anette; Nilsson, Andreas; Stanton, Tania; Muscheler, Raimund; Snowball, Ian

2013-04-01

Well-dated natural archives are crucial when investigating the timing between climate change and climate forcing. Annually laminated (varved) lake sediments, in particular, can provide valuable knowledge about past climatic and environmental conditions as the annual nature of the sediments enables the establishment of high-resolution archives. In addition, lake sediments can record variations in the Earth's magnetic field, which has the potential to be used as a dating validation technique if the palaeo-secular and -intensity curves are dated correctly. If individual and well-defined geomagnetic events can be dated accurately, they can then be used as isochrones, thereby allowing the synchronisation of different records. We therefore aim to date the "f" event, a late Holocene secular variation change, which is recorded in many sites in the northern hemisphere. Varved sites in Sweden have dated the "f" event to ~2700 cal. yrs BP. In order to constrain this date further, we have used the radiocarbon wiggle-matching method on a lake in central west Sweden, Kälksjön (Stanton et al., 2010), whose chronology has previously been validated using a number of complimentary dating methods. With the radiocarbon wiggle-matching technique, closely spaced samples are measured and matched to distinct wiggles in the radiocarbon calibration curve. The advantage of using varve-dated sediments is that it is possible to know the exact number of years between each sample, and therefore improve the initial age model. We compare the wiggle-match results of Kälksjön with results from a newly discovered varved lake sediment sequence in southern Sweden, Gyltigesjön. This comparison can provide information about magnetisation processes in sediments, such as the length of the palaeomagnetic lock-in delay. Stanton, T., Snowball, I., Zillén, L., Wastegård, S., 2010. Validating a Swedish varve chronology using radiocarbon, palaeomagnetic secular variation, lead pollution history and

The effect of changing land use on soil radiocarbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrison, K.G.; Broecker, W.S.; Bonani, G.

Most carbon budgets require greening of the terrestrial biosphere as a sink for some of the excess carbon dioxide produced by fossil fuel burning and deforestation. Much of this storage is thought to occur in soils, but running counter to this conclusion is the observation that cultivation has reduced the agricultural reservoir of soil humus. Radiocarbon measurements in agricultural soils lend support to this browning of agricultural lands. Moreover, the loss is from the fast cycling portion of the humus.

Radiocarbon ages on late pleistocene loess stratigraphy of Nebraska and Kansas, Central Great Plains, U.S.A.

NASA Astrophysics Data System (ADS)

Martin, Charles W.

In the central Great Plains of the United States, radiocarbon dating of loess and buried soils is clarifying the late Quaternary loess chronology for the period 25,000 to 10,000 BP. Along Harland Lake, Nebraska, a soil developed in the Gilman Canyon Formation and overlain by Peoria Loess has radiocarbon ages on soil humates of 30,700 to 21,500 BP. At one site, two Picea charcoal bands in the lower meter of Peoria Loess have radiocarbon ages of 21,250 and 19,730 BP. Therefore, in the vicinity of Harlan Lake, deposition of Peoria Loess apparently began around 21,000 BP. Peoria Loess deposition appears to have been interrupted by an episode of river entrenchment prior to 12,600 BP. Spring activity shortly thereafter suggests that incision was coeval to an increase in effective moisture. The termination of Peoria Loess deposition is marked by the Brady Soil, which in the Harlan Lake area has radiocarbon ages on soil humates of 11,800 to 10,200 BP. Comparison of the Harlan Lake chronology with chronologies completed elsewhere in the central Great Plains reveals general synchrony among periods of pedogenesis and Peoria Loess deposition. Little is known, however, about vegetation conditions in the region when loess was accumulating. Charcoal has been noted chiefly in the basal Peoria Loess, suggesting that some trees were present during initial Peoria Loess deposition. The extent of this tree cover is unknown, however. Charcoal is rare in the middle and upper Peoria Loess.

New radiocarbon dates for Columbian mammoth and Mexican horse from southern Alberta and the Lateglacial regional fauna

NASA Astrophysics Data System (ADS)

Hills, Leonard V.; Harington, C. Richard

2003-06-01

New radiocarbon dates on Columbian mammoth ( Mammuthus columbi) and Mexican horse ( Equus conversidens) specimens from southern Alberta are 10,930±100 BP and 10,870±45 years BP, respectively—older than originally thought. These specimens are reviewed in the light of 10 other sites in southern Alberta that have yielded large mammal remains radiocarbon dated to about 11,000 BP. Thus, the regional fauna includes at least 11 mammalian species. This fauna was not restricted to the foothills, but extended well onto the plains and may prove useful in correlating foothills terraces with those of the plains.

Comparative study on the immunogenicity and safety of a purified chick embryo cell rabies vaccine (PCECV) administered according to two different simulated post exposure intramuscular regimens (Zagreb versus Essen).

PubMed

Mahendra, B J; Narayana, Dh Ashwath; Agarkhedkar, Sharad; Ravish, H S; Harish, B R; Agarkhedkar, Shalaka; Madhusudana, S N; Belludi, Ashwin; Ahmed, Khaleel; Jonnalagedda, Rekha; Vakil, Hoshang; Bhusal, Chiranjiwi; Arora, Ashwani Kumar

2015-01-01

Despite availability of effective rabies vaccines, India has the highest global mortality rate for rabies. Low socio-economic communities are most affected due to lack of awareness of the disease and poor compliance to post-exposure prophylactic regimens. Currently, the only approved intramuscular regimen for post-exposure prophylaxis (PEP) against rabies in India is the Essen regimen, which consists of 5 injections administered over 5 separate days in a period of one month. The high number of doses and clinical visits, however, are major reasons for non-compliance, and thus a shorter regimen would be beneficial. In a simulated PEP trial in healthy, adult subjects, this study evaluated whether purified chick embryo cell vaccine (PCECV), administered according to the WHO-recommended 4-dose/3 visit Zagreb vaccination regimen is of equal immunogenicity and safety as the standard Essen regimen in Indian subjects. Two hundred and 50 healthy adults were enrolled and randomized into a Zagreb or Essen group, each receiving PCECV according to their respective regimen. Blood samples were collected on Days 0, 7, 14 and 42 and analyzed using the rapid fluorescent focus inhibition test (RFFIT). By Day 14, all subjects across both groups attained rabies virus neutralizing antibody (RVNA) concentrations of ≥ 0.5IU/ml. The Zagreb regimen was then demonstrated to be immunologically non-inferior to the Essen regimen by Day 14, which was the primary endpoint of the study. No safety issues were noted and the occurrence of adverse events was similar in both groups (17% and 15%, respectively). NCT01365494. CTRI No.: CTRI/2011/07/001857.

Alkenone radiocarbon stratigraphy at high resolution continental marigin sites

NASA Astrophysics Data System (ADS)

Mollenhauer, G.; Eglinton, T.; Freudenthal, T.; Lamy, F.

2003-04-01

Radiocarbon stratigraphy is an essential tool for high resolution Late Quaternary paleoceanographic studies. For this purpose, radiocarbon ages of foraminifera have been extensively measured. Age models based on these measurements are commonly applied to a wide range of sediment proxy information, including the investigation of temporal leads and lags. The critical assumption made in these studies is that temporal coupling between foraminifera and other sediment constituents, including specific biomarkers of marine phytoplankton, e.g. alkenones, is maintained in the sediments. A recent study using coupled foraminifera and alkenone ages was conducted at a high sedimentation rate site situated at the Bermuda Rise sediment drift body. Ages of formanifera and alkenones differed by up to 8000 years. As an interpreation of these data, it was suggested that sediment constituents residing in different grain size fractions may have different current transport properties and may thus originate from different source areas separated by large geographical distances. Sediment retrieved from a site influenced by lateral advection would thus have to be regarded as a mixture of material from different sources. The time span between production and final deposition may be site dependent and remains largely unknown. Continental margins underlying high productivity areas are sites of high sediment accumulation. The major part of this sediment is believed to be biogenic and is produced in the overlying water column. Sediment particles are expected to be deposited rapidly at or near the site of production regardless of their size. To evaluate this premise, we have measured coupled radiocarbon ages of foraminifera, TOC and alkenones in samples taken from sediment cores retreived from three continental margin high accumulation rate sites. Cores from the Benguela upwelling system, the North West African upwelling system and from the Chilean margin high productivity area were chosen. All

Characterization of Arctic elemental carbon in Barrow, AK using radiocarbon source apportionment

NASA Astrophysics Data System (ADS)

Barrett, T. E.; Usenko, S.; Robinson, E. M.; Sheesley, R. J.

2013-12-01

Currently, the Arctic is one of the fastest warming regions on earth with surface temperatures increasing at a rate nearly double the global mean over recent decades. Despite the fact that atmospheric concentrations of elemental carbon (EC) are lower in the Arctic than in lower latitudes, deposition of EC on snow and ice may exacerbate regional warming by simultaneously decreasing albedo and increasing melt rates. Due to the intensifying Arctic oil exploration in areas such as the Beaufort and Chukchi seas, the impact of new emission sources such as heavy fuel and heavy diesel combustion on regional carbon needs to be assessed. The first step in developing mitigation strategies for reducing current and future EC emissions in the Arctic is to determine emission source contributions. This study aims to determine the relative contributions of fossil fuel and biomass combustion and to identify major source regions of EC to the Arctic. Radiocarbon analysis of both total organic carbon (TOC) and EC combined with organic tracer and back trajectory analysis has been applied to a set of wintertime coarse particulate matter (PM10) samples from Barrow, AK. Preliminary apportionment for January 2013 indicates roughly half of TOC is from biogenic/biomass burning emissions and one third of EC is due to biomass burning emissions. The radiocarbon results will be combined with organic tracer analysis (polycyclic aromatic hydrocarbons, petroleum biomarkers and normal alkanes), increasing the specificity of the relative contribution of both the fossil and modern (biogenic/biomass burning) carbon emission sources. This research represents the first reported radiocarbon values for Arctic EC, providing highly conclusive source apportionment prior to the influence of increased drilling operations and ship traffic in the Beaufort and Chukchi seas.

Millennial-scale variability in the local radiocarbon reservoir age of the Florida Keys reef tract during the Holocene

NASA Astrophysics Data System (ADS)

Ashe, E.; Toth, L. T.; Cheng, H.; Edwards, R. L.; Richey, J. N.

2016-12-01

The oceanic passage between the Florida Keys and Cuba, known as the Straits of Florida, provides a critical connection between the tropics and northern Atlantic. Changes in the character of water masses transported through this region may ultimately have important impacts on high-latitude climate variability. Although recent studies have documented significant changes in the density of regional surface waters over millennial timescales, little is known about the contribution of local- to regional-scale changes in circulation to surface-water variability. Local variability in the radiocarbon age, ΔR, of surface waters can be used to trace changes in local water-column mixing and/or changes in regional source water over a variety of spatial and temporal scales. We reconstructed "snapshots" of ΔR variability across the Florida Keys reef tract during the last 10,000 years by dating 68 unaltered corals collected from Holocene reef cores with both U-series and radiocarbon techniques. We combined the snapshots of ΔR into a semi-empirical model to develop a robust statistical reconstruction of millennial-scale variability in ΔR on the Florida Keys reef tract. Our model demonstrates that ΔR varied significantly during the Holocene, with relatively high values during the early Holocene and around 3000 years BP and relatively low values around 7000 years BP and at present. We compare the trends in ΔR to existing paleoceanographic reconstructions to evaluate the relative contribution of local upwelling versus changes in source water to the region as a whole in driving local radiocarbon variability, and discuss the importance of these results to our understanding of regional-scale oceanographic and climatic variability during the Holocene. We also discuss the implications of our results for radiocarbon dating of marine samples from south Florida and present a model of ΔR versus 14C age that can be used to improve the accuracy of radiocarbon calibrations from this region.

The radiocarbon signature of microorganisms in the mesopelagic ocean.

PubMed

Hansman, Roberta L; Griffin, Sheila; Watson, Jordan T; Druffel, Ellen R M; Ingalls, Anitra E; Pearson, Ann; Aluwihare, Lihini I

2009-04-21

Several lines of evidence indicate that microorganisms in the meso- and bathypelagic ocean are metabolically active and respiring carbon. In addition, growing evidence suggests that archaea are fixing inorganic carbon in this environment. However, direct quantification of the contribution from deep ocean carbon sources to community production in the dark ocean remains a challenge. In this study, carbon flow through the microbial community at 2 depths in the mesopelagic zone of the North Pacific Subtropical Gyre was examined by exploiting the unique radiocarbon signatures (Delta(14)C) of the 3 major carbon sources in this environment. The radiocarbon content of nucleic acids, a biomarker for viable cells, isolated from size-fractionated particles (0.2-0.5 microm and >0.5 microm) showed the direct incorporation of carbon delivered by rapidly sinking particles. Most significantly, at the 2 mesopelagic depths examined (670 m and 915 m), carbon derived from in situ autotrophic fixation supported a significant fraction of the free-living microbial community (0.2-0.5 microm size fraction), but the contribution of chemoautotrophy varied markedly between the 2 depths. Results further showed that utilization of the ocean's largest reduced carbon reservoir, (14)C-depleted, dissolved organic carbon, was negligible in this environment. This isotopic portrait of carbon assimilation by the in situ, free-living microbial community, integrated over >50,000 L of seawater, implies that recent, photosynthetic carbon is not always the major carbon source supporting microbial community production in the mesopelagic realm.

RADIOCARBON 14C MEASUREMENTS ON ATMOSPHERIC SAMPLES OF PARTICULATE MATTER (& VOLATILE ORGANIC COMPOUNDS)

EPA Science Inventory

Following a brief history of radiocarbon work at EPA since the 1980's, the presentation focuses on recent non-winter measurements for PM-2.5 in the Southeastern U.S. (Houston, TX; Nashville, TN; and particularly, Tampa, FL) and what the measurements suggest about the importance o...

A portable molecular-sieve-based CO2 sampling system for radiocarbon measurements

NASA Astrophysics Data System (ADS)

Palonen, V.

2015-12-01

We have developed a field-capable sampling system for the collection of CO2 samples for radiocarbon-concentration measurements. Most target systems in environmental research are limited in volume and CO2 concentration, making conventional flask sampling hard or impossible for radiocarbon studies. The present system captures the CO2 selectively to cartridges containing 13X molecular sieve material. The sampling does not introduce significant under-pressures or significant losses of moisture to the target system, making it suitable for most environmental targets. The system also incorporates a significantly larger sieve container for the removal of CO2 from chambers prior to the CO2 build-up phase and sampling. In addition, both the CO2 and H2O content of the sample gas are measured continuously. This enables in situ estimation of the amount of collected CO2 and the determination of CO2 flux to a chamber. The portable sampling system is described in detail and tests for the reliability of the method are presented.

A portable molecular-sieve-based CO2 sampling system for radiocarbon measurements.

PubMed

Palonen, V

2015-12-01

We have developed a field-capable sampling system for the collection of CO2 samples for radiocarbon-concentration measurements. Most target systems in environmental research are limited in volume and CO2 concentration, making conventional flask sampling hard or impossible for radiocarbon studies. The present system captures the CO2 selectively to cartridges containing 13X molecular sieve material. The sampling does not introduce significant under-pressures or significant losses of moisture to the target system, making it suitable for most environmental targets. The system also incorporates a significantly larger sieve container for the removal of CO2 from chambers prior to the CO2 build-up phase and sampling. In addition, both the CO2 and H2O content of the sample gas are measured continuously. This enables in situ estimation of the amount of collected CO2 and the determination of CO2 flux to a chamber. The portable sampling system is described in detail and tests for the reliability of the method are presented.

Assessing Soil Organic C Stability at the Continental Scale: An Analysis of Soil C and Radiocarbon Profiles Across the NEON Sites

NASA Astrophysics Data System (ADS)

Heckman, K. A.; Gallo, A.; Hatten, J. A.; Swanston, C.; McKnight, D. M.; Strahm, B. D.; Sanclements, M.

2017-12-01

Soil carbon stocks have become recognized as increasingly important in the context of climate change and global C cycle modeling. As modelers seek to identify key parameters affecting the size and stability of belowground C stocks, attention has been drawn to the mineral matrix and the soil physiochemical factors influenced by it. Though clay content has often been utilized as a convenient and key explanatory variable for soil C dynamics, its utility has recently come under scrutiny as new paradigms of soil organic matter stabilization have been developed. We utilized soil cores from a range of National Ecological Observatory Network (NEON) experimental plots to examine the influence of physicochemical parameters on soil C stocks and turnover, and their relative importance in comparison to climatic variables. Soils were cored at NEON sites, sampled by genetic horizon, and density separated into light fractions (particulate organics neither occluded within aggregates nor associated with mineral surfaces), occluded fractions (particulate organics occluded within aggregates), and heavy fractions (organics associated with mineral surfaces). Bulk soils and density fractions were measured for % C and radiocarbon abundance (as a measure of C stability). Carbon and radiocarbon abundances were examined among fractions and in the context of climatic variables (temperature, precipitation, elevation) and soil physiochemical variables (% clay and pH). No direct relationships between temperature and soil C or radiocarbon abundances were found. As a whole, soil radiocarbon abundance in density fractions decreased in the order of light>heavy>occluded, highlighting the importance of both surface sorption and aggregation to the preservation of organics. Radiocarbon abundance was correlated with pH, with variance also grouping by dominate vegetation type. Soil order was also identified as an important proxy variable for C and radiocarbon abundance. Preliminary results suggest that

Assessment of Contribution of Contemporary Carbon Sources to Size-Fractionated Particulate Matter and Time-Resolved Bulk Particulate Matter Using the Measurement of Radiocarbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hwang, H M; Young, T M; Buchholz, B A

2009-04-16

This study was motivated by a desire to improve understanding of the sources contributing to the carbon that is an important component of airborne particulate matter (PM). The ultimate goal of this project was to lay a ground work for future tools that might be easily implemented with archived or routinely collected samples. A key feature of this study was application of radiocarbon measurement that can be interpreted to indicate the relative contributions from fossil and non-fossil carbon sources of atmospheric PM. Size-resolved PM and time-resolved PM{sub 10} collected from a site in Sacramento, CA in November 2007 (Phase I)more » and March 2008 (Phase II) were analyzed for radiocarbon and source markers such as levoglucosan, cholesterol, and elemental carbon. Radiocarbon data indicates that the contributions of non-fossil carbon sources were much greater than that from fossil carbon sources in all samples. Radiocarbon and source marker measurements confirm that a greater contribution of non-fossil carbon sources in Phase I samples was highly likely due to residential wood combustion. The present study proves that measurement of radiocarbon and source markers can be readily applied to archived or routinely collected samples for better characterization of PM sources. More accurate source apportionment will support ARB in developing more efficient control strategies.« less

Rate estimates for lateral bedrock erosion based on radiocarbon ages, Duck River, Tennessee

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brakenridge, G.R.

Rates of bedrock erosion in ingrown meandering rivers can be inferred from the location of buried relict flood-plain and river-bank surfaces, associated paleosols, and radiocarbon dates. Two independent methods are used to evaluate the long-term rates of limestone bedrock erosion by the Duck River. Radiocarbon dates on samples retrieved from buried Holocene flood-plain and bank surfaces indicate lateral migration of the river bank at average rates of 0.6-1.9 m/100 yr. Such rates agree with lateral bedrock cliff erosion rates of 0.5-1.4 m/100 yr, as determined from a comparison of late Pleistocene and modern bedrock cliff and terrace scarp positions. Thesemore » results show that lateral bedrock erosion by this river could have occurred coevally with flood-plain and terrace formation and that the resulting evolution of valley meander bends carved into bedrock is similar in many respects to that of channel meanders cut into alluvium. 11 references, 5 figures.« less

Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus).

PubMed

Nielsen, Julius; Hedeholm, Rasmus B; Heinemeier, Jan; Bushnell, Peter G; Christiansen, Jørgen S; Olsen, Jesper; Ramsey, Christopher Bronk; Brill, Richard W; Simon, Malene; Steffensen, Kirstine F; Steffensen, John F

2016-08-12

The Greenland shark (Somniosus microcephalus), an iconic species of the Arctic Seas, grows slowly and reaches >500 centimeters (cm) in total length, suggesting a life span well beyond those of other vertebrates. Radiocarbon dating of eye lens nuclei from 28 female Greenland sharks (81 to 502 cm in total length) revealed a life span of at least 272 years. Only the smallest sharks (220 cm or less) showed signs of the radiocarbon bomb pulse, a time marker of the early 1960s. The age ranges of prebomb sharks (reported as midpoint and extent of the 95.4% probability range) revealed the age at sexual maturity to be at least 156 ± 22 years, and the largest animal (502 cm) to be 392 ± 120 years old. Our results show that the Greenland shark is the longest-lived vertebrate known, and they raise concerns about species conservation. Copyright © 2016, American Association for the Advancement of Science.

Direct radiocarbon dating and DNA analysis of the Darra-i-Kur (Afghanistan) human temporal bone.

PubMed

Douka, Katerina; Slon, Viviane; Stringer, Chris; Potts, Richard; Hübner, Alexander; Meyer, Matthias; Spoor, Fred; Pääbo, Svante; Higham, Tom

2017-06-01

The temporal bone discovered in the 1960s from the Darra-i-Kur cave in Afghanistan is often cited as one of the very few Pleistocene human fossils from Central Asia. Here we report the first direct radiocarbon date for the specimen and the genetic analyses of DNA extracted and sequenced from two areas of the bone. The new radiocarbon determination places the find to ∼4500 cal BP (∼2500 BCE) contradicting an assumed Palaeolithic age of ∼30,000 years, as originally suggested. The DNA retrieved from the specimen originates from a male individual who carried mitochondrial DNA of the modern human type. The petrous part yielded more endogenous ancient DNA molecules than the squamous part of the same bone. Molecular dating of the Darra-i-Kur mitochondrial DNA sequence corroborates the radiocarbon date and suggests that the specimen is younger than previously thought. Taken together, the results consolidate the fact that the human bone is not associated with the Pleistocene-age deposits of Darra-i-Kur; instead it is intrusive, possibly re-deposited from upper levels dating to much later periods (Neolithic). Despite its Holocene age, the Darra-i-Kur specimen is, so far, the first and only ancient human from Afghanistan whose DNA has been sequenced. Copyright © 2017 Elsevier Ltd. All rights reserved.

Immunogenicity and safety of purified chick-embryo cell rabies vaccine under Zagreb 2-1-1 or 5-dose Essen regimen in Chinese children 6 to 17 years old and adults over 50 years: a randomized open-label study.

PubMed

Li, RongCheng; Li, YanPing; Wen, ShuQing; Wen, HuiChun; Nong, Yi; Mo, Zhaojun; Xie, Fang; Pellegrini, Michele

2015-01-01

The aim of this Phase IIIb, open-label, randomized study was to demonstrate the non-inferiority of immune responses and to assess the safety of a purified chick-embryo cell rabies vaccine (PCECV) in healthy Chinese children (6 to 17 years) and older adults (≥51 years) following 2 alternative intramuscular (IM) simulated post-exposure prophylaxis (PEP) regimens: 4-dose Zagreb or 5-dose Essen regimen. Serum samples were collected prior to vaccination on Days 1 and 15 and on day 43 to assess immune response by rabies virus neutralizing antibody (RVNA) concentrations. Solicited adverse events (AEs) were recorded for up to 7 days following each vaccine dose, and unsolicited AEs throughout the entire study period. PCECV vaccination induced a strong immune response at Day 15, and the non-inferiority in immune response of the Zagreb vs. the Essen regimen was demonstrated in children and older adults. At Day 15,100% of children (N = 224), and 99% of subjects ≥51 years of age (N = 376) developed adequate RVNA concentrations (≥0.5 IU/mL); at Day 43 all subjects achieved RVNA concentrations ≥0.5 IU/mL, for both PEP regimens. The well-known tolerability and safety profile of the PCECV was again observed in this study following either Zagreb or Essen regimens. Rabies PEP vaccination with PCECV following a Zagreb regimen induced immune responses non-inferior to those of the Essen regimen, and had a similar safety and tolerability profile to the Essen regimen in Chinese children, adolescents, and adults over 51 years. ClinicalTrials.gov identifier: NCT01680016.

Increase of radiocarbon concentration in tree rings from Kujawy (SE Poland) around AD 774-775

NASA Astrophysics Data System (ADS)

Rakowski, Andrzej Z.; Krąpiec, Marek; Huels, Mathias; Pawlyta, Jacek; Dreves, Alexander; Meadows, John

2015-10-01

Evidence of a rapid increase in atmospheric radiocarbon (14C) content in AD 774-775 was presented by Miyake et al. (2012), who observed an increase of about 12‰ in the 14C content in annual tree rings from Japanese cedar. Usoskin et al. (2013) report a similar 14C spike in German oak, and attribute it to exceptional solar activity. If this phenomenon is global in character, such rapid changes in 14C concentration may affect the accuracy of calibrated dates, as the existing calibration curve is composed mainly of decadal samples. Single-year samples of dendro-chronologically dated tree rings of deciduous oak (Quercus robur) from Kujawy, a village near Krakow (SE Poland), spanning the years AD 765-796, were collected and their 14C content was measured using the AMS system in the Leibniz Laboratory. The results clearly show a rapid increase of 9.2 ± 2.1‰ in the 14C concentration in tree rings between AD 774 and AD 775, with maximum Δ14C = 4.1 ± 2.3‰ noted in AD 776.

High precise measurements of cosmogenic radiocarbon abundance by complex of scintillation equipments

NASA Technical Reports Server (NTRS)

Kocharov, G. E.; Metskvarishvili, R. Y.; Tsereteli, S. L.

1985-01-01

The main characteristics of scintillation equipments which enable the measurements of radiocarbon content with high accuracy of 0.2 to 0.3% were considered. The complex of scintillation devices operated very well for the last 15 years and allowed the investigation of the temporal variation of solar activity and intensity of cosmic rays for the last 300 years.

Analysis of biennial outbreak pattern of respiratory syncytial virus according to subtype (A and B) in the Zagreb region.

PubMed

Mlinaric-Galinovic, Gordana; Tabain, Irena; Kukovec, Tamara; Vojnovic, Gordana; Bozikov, Jadranka; Bogovic-Cepin, Jasna; Ivkovic-Jurekovic, Irena; Knezovic, Ivica; Tesovic, Goran; Welliver, Robert C

2012-06-01

The epidemic pattern of respiratory syncytial virus (RSV) in Croatia is biennial. In order to determine if the circulation of different RSV subtypes affects the outbreak cycle, the aim of the present study was to analyze the epidemic pattern of RSV in children in Croatia (Zagreb region) over a period of 3 consecutive years. The study group consisted of 696 inpatients, aged 0-5 years, who were hospitalized with acute respiratory tract infections caused by RSV, in Zagreb, in the period 1 January 2006-31 December 2008. The virus was identified in nasopharyngeal secretions using direct immunofluorescence. The virus subtype was determined on real-time polymerase chain reaction. Of 696 RSV infections identified in children, subtype A virus caused 374 infections, and subtype B, 318. Four patients had a dual RSV infection (subtypes A and B). The period of study was characterized by four epidemic waves of RSV infections: the first, smaller, in the spring of 2006; the second, larger, in December 2006/January 2007; the third in spring 2008, followed by a fourth outbreak beginning in November of 2008. The biennial virus cycles were persistent although the predominant RSV subtype in the first two epidemic waves was subtype B, and in the second two it was subtype A. Over a 3 year period of observation, the biennial RSV cycle in Croatia cannot be explained by a difference in the predominant circulating subtype of RSV. Other unknown factors account for the biennial cycle of RSV epidemics in Croatia. © 2011 The Authors. Pediatrics International © 2011 Japan Pediatric Society.

Drivers of soil organic matter vulnerability to climate change. Part I: Laboratory incubations of Swiss forest soils and radiocarbon analysis

NASA Astrophysics Data System (ADS)

González Domínguez, Beatriz; Studer, Mirjam S.; Niklaus, Pascal A.; Haghipour, Negar; McIntyre, Cameron; Wacker, Lukas; Zimmermann, Stephan; Walthert, Lorenz; Hagedorn, Frank; Abiven, Samuel

2016-04-01

Given the key role of soil organic carbon (SOC) on climate and greenhouse gas regulation, there is an increasing need to incorporate the carbon (C) feedback between SOC and the atmosphere into earth system models. The evaluation of these models points towards uncertainties on the response of CO2-C fluxes, derived from the decomposition of SOC, to the influence of controls/drivers. SOC vulnerability refers to the likelihood of losing previously stabilized soil organic matter, by the effect of environmental factors. The objective of this study is to produce a SOC vulnerability ranking of soils and to provide new insights into the influence of environmental and soil properties controls. Research on SOC vulnerability tends to focus on climatic controls and neglect the effect of other factors, such as soil geochemistry and mineralogy, on C stabilization/de-stabilization processes. In this work, we hypothesized that climate (mean annual temperature and soil moisture status proxy at the research sites in the period 1981-2010), soil (pH and % clay) and terrain (slope gradient and orientation) characteristics are the main controls of the CO2-C fluxes from SOC. Following a statistics-based approach, we selected 54 forest sites across Switzerland, which cover a broad spectrum of values for the hypothesized controls. Then, we selected the study sites so that the controls are orthogonal to each other; thus, their effect was not confounded. At each site, we collected three non-overlapping topsoil (i.e. 20 cm) composites within 40 x 40 m2 plots. In the laboratory, we sieved fresh soils at 2 mm and run a 2-weeks pre-incubation, before beginning a 6-months aerobic soil incubation under controlled conditions of moisture and temperature. Periodically, we collected NaOH (1M) traps containing the CO2-C derived from microbial heterotrophic respiration. We calculated the cumulative CO2-C respired and the one-pool SOC decomposition rates from the 54 forest sites, and linked these data to

Radiocarbon dating of charcoal and bone collagen associated with early pottery at Yuchanyan Cave, Hunan Province, China

PubMed Central

Boaretto, Elisabetta; Wu, Xiaohong; Yuan, Jiarong; Bar-Yosef, Ofer; Chu, Vikki; Pan, Yan; Liu, Kexin; Cohen, David; Jiao, Tianlong; Li, Shuicheng; Gu, Haibin; Goldberg, Paul; Weiner, Steve

2009-01-01

Yuchanyan Cave in Daoxian County, Hunan Province (People's Republic of China), yielded fragmentary remains of 2 or more ceramic vessels, in addition to large amounts of ash, a rich animal bone assemblage, cobble and flake artifacts, bone tools, and shell tools. The artifacts indicate that the cave was a Late Paleolithic foragers' camp. Here we report on the radiocarbon ages of the sediments based on analyses of charcoal and bone collagen. The best-preserved charcoal and bone samples were identified by prescreening in the field and laboratory. The dates range from around 21,000 to 13,800 cal BP. We show that the age of the ancient pottery ranges between 18,300 and 15,430 cal BP. Charcoal and bone collagen samples located above and below one of the fragments produced dates of around 18,000. These ceramic potsherds therefore provide some of the earliest evidence for pottery making in China. PMID:19487667

Co-Development of Conceptual Understanding and Critical Attitude: Analyzing Texts on Radiocarbon Dating

ERIC Educational Resources Information Center

Décamp, N.; Viennot, L.

2015-01-01

This research documents the impact of a teaching interview aimed at developing a critical attitude in students, and focused on a particular topic: radiocarbon dating. This teaching interview is designed to observe students' reaction to limited written explanations of the phenomenon under study, and their possible frustration or intellectual…

Difference in radiocarbon ages of carbonized material from the inner and outer surfaces of pottery from a wetland archaeological site.

PubMed

Miyata, Yoshiki; Minami, Masayo; Onbe, Shin; Sakamoto, Minoru; Matsuzaki, Hiroyuki; Nakamura, Toshio; Imamura, Mineo

2011-01-01

AMS (Accelerator Mass Spectrometry) radiocarbon dates for eight potsherds from a single piece of pottery from a wetland archaeological site indicated that charred material from the inner pottery surfaces (5052 ± 12 BP; N = 5) is about 90 (14)C years older than that from the outer surfaces (4961 ± 22 BP; N = 7). We considered three possible causes of this difference: the old wood effect, reservoir effects, and diagenesis. We concluded that differences in the radiocarbon ages between materials from the inner and outer surfaces of the same pot were caused either by the freshwater reservoir effect or by diagenesis. Moreover, we found that the radiocarbon ages of carbonized material on outer surfaces (soot) of pottery from other wetland archaeological sites were the same as the ages of material on inner surfaces (charred food) of the same pot within error, suggesting absence of freshwater reservoir effect or diagenesis.

Correlation between Annual Corn Crop per Hectare in Croatia and Drought Indices for Zagreb-Gric Observatory

NASA Astrophysics Data System (ADS)

Pandzic, Kreso; Likso, Tanja

2017-04-01

Correlation coefficients between annual corn crop per hectare in Croatia and 9-month Standardized Precipitation Index (SPI) and Palmer Drought Severity Index (PDSI) for Zagreb - Gric for August are shown as significant. The results indicate that there is also a significant correlation between those drought indices and drought damages. Thus a forecast of the indices for August could be used for estimation e.g. annual corn crop per hectare in Croatia. Better results could be expected if statistical relationship between annual corn crops per hectare will be considered on county level instead the whole Croatia and indices calculated for weather stations for the same county. Effective way for reduction of drought damages is irrigation which need to be significantly improved in future in Croatia

A reevaluation of the Pallett Creek earthquake chronology based on new AMS radiocarbon dates, San Andreas fault, California

NASA Astrophysics Data System (ADS)

Scharer, Katherine M.; Biasi, Glenn P.; Weldon, Ray J., II

2011-12-01

The Pallett Creek paleoseismic record occupies a keystone position in most attempts to develop rupture histories for the southern San Andreas fault. Previous estimates of earthquake ages at Pallett Creek were determined by decay counting radiocarbon methods. That method requires large samples which can lead to unaccounted sources of uncertainty in radiocarbon ages because of the heterogeneous composition of organic layers. In contrast, accelerator mass spectrometry (AMS) radiocarbon dates may be obtained from small samples that have known carbon sources and also allow for a more complete sampling of the section. We present 65 new AMS radiocarbon dates that span nine ground-rupturing earthquakes at Pallett Creek. Overall, the AMS dates are similar to and reveal no dramatic bias in the conventional dates. For many layers, however, individual charcoal samples were younger than the conventional dates, leading to earthquake ages that are overall slightly younger than previously reported. New earthquake ages are determined by Bayesian refinement of the layer ages based on stratigraphic ordering and sedimentological constraints. The new chronology is more regular than previously published records in large part due to new samples constraining the age of event R. The closed interval from event C to 1857 has a mean recurrence of 135 years (σ = 83.2 years) and a quasiperiodic coefficient of variation (COV) of 0.61. We show that the new dates and resultant earthquake chronology have a stronger effect on COV than the specific membership of this long series and dating precision improvements from sedimentation rates.

Radiocarbon and stable isotope investigations at the Central Rhineland sites of Gönnersdorf and Andernach-Martinsberg, Germany.

PubMed

Stevens, Rhiannon E; O'Connell, Tamsin C; Hedges, Robert E M; Street, Martin

2009-08-01

The late glacial open-air sites of Gönnersdorf and Andernach-Martinsberg in the German Central Rhineland are well known for their Magdalenian occupation and activities. The latter site also produced evidence for a younger, Final Palaeolithic occupation of the locality by people of the Federmessergruppen. Both sites are particularly well preserved, largely due to their burial beneath volcanic deposits of the late glacial Laacher See eruption. We conducted a program of AMS radiocarbon dating and stable isotope analyses with the aim of improving understanding of the chronological history and ecological setting of the two sites. Previously published radiocarbon dates appeared to indicate that the earliest Magdalenian occupation at Gönnersdorf fell around 12,900 uncalibrated (14)C yr BP, while the earliest occupation at Andernach may have been more than 500 radiocarbon years earlier. The AMS determinations presented here revise this impression and suggest that the onset of occupation at the two sites was in fact simultaneous and prior to the warming of Greenland Interstadial GI 1e. At Gönnersdorf, a chronological hiatus exists between the main Magdalenian faunal assemblage and mega-faunal remains interpreted as collected sub-fossil material. At Andernach-Martinsberg, there is a clear chronological hiatus between the Magdalenian occupation and subsequent Federmessergruppen activities at the site. However, an intermediate radiocarbon date on an atypically preserved horse bone is suggestive of ephemeral human visits to the site between these well demonstrated phases. A date of similar age on an elk bone from Gönnersdorf may indicate broadly contemporaneous human presence at Gönnersdorf too. Stable isotope analysis of faunal remains from Gönnersdorf and Andernach-Martinsberg was conducted with the aim of both reconstructing and comparing local environmental conditions at the two sites, and also potentially identifying subtle variations in the chronological development

Comparative study on the immunogenicity and safety of a purified chick embryo cell rabies vaccine (PCECV) administered according to two different simulated post exposure intramuscular regimens (Zagreb versus Essen)

PubMed Central

Mahendra, BJ; Narayana, DH Ashwath; Agarkhedkar, Sharad; Ravish, HS; Harish, BR; Agarkhedkar, Shalaka; Madhusudana, SN; Belludi, Ashwin; Ahmed, Khaleel; Jonnalagedda, Rekha; Vakil, Hoshang; Bhusal, Chiranjiwi; Arora, Ashwani Kumar

2015-01-01

Despite availability of effective rabies vaccines, India has the highest global mortality rate for rabies. Low socio-economic communities are most affected due to lack of awareness of the disease and poor compliance to post-exposure prophylactic regimens. Currently, the only approved intramuscular regimen for post-exposure prophylaxis (PEP) against rabies in India is the Essen regimen, which consists of 5 injections administered over 5 separate days in a period of one month. The high number of doses and clinical visits, however, are major reasons for non-compliance, and thus a shorter regimen would be beneficial. In a simulated PEP trial in healthy, adult subjects, this study evaluated whether purified chick embryo cell vaccine (PCECV), administered according to the WHO-recommended 4-dose/3 visit Zagreb vaccination regimen is of equal immunogenicity and safety as the standard Essen regimen in Indian subjects. Two hundred and 50 healthy adults were enrolled and randomized into a Zagreb or Essen group, each receiving PCECV according to their respective regimen. Blood samples were collected on Days 0, 7, 14 and 42 and analyzed using the rapid fluorescent focus inhibition test (RFFIT). By Day 14, all subjects across both groups attained rabies virus neutralizing antibody (RVNA) concentrations of ≥ 0.5IU/ml. The Zagreb regimen was then demonstrated to be immunologically non-inferior to the Essen regimen by Day 14, which was the primary endpoint of the study. No safety issues were noted and the occurrence of adverse events was similar in both groups (17% and 15%, respectively). NCT01365494. CTRI No.: CTRI/2011/07/001857 PMID:25692792

Test of Martin's overkill hypothesis using radiocarbon dates on extinct megafauna.

PubMed

Surovell, Todd A; Pelton, Spencer R; Anderson-Sprecher, Richard; Myers, Adam D

2016-01-26

Following Martin [Martin PS (1973) Science 179:969-974], we propose the hypothesis that the timing of human arrival to the New World can be assessed by examining the ecological impacts of a small population of people on extinct Pleistocene megafauna. To that end, we compiled lists of direct radiocarbon dates on paleontological specimens of extinct genera from North and South America with the expectation that the initial decline of extinct megafauna should correspond in time with the initial evidence for human colonization and that those declines should occur first in eastern Beringia, next in the contiguous United States, and last in South America. Analyses of spacings and frequency distributions of radiocarbon dates for each region support the idea that the extinction event first commenced in Beringia, roughly 13,300-15,000 BP. For the United States and South America, extinctions commenced considerably later but were closely spaced in time. For the contiguous United States, extinction began at ca. 12,900-13,200 BP, and at ca. 12,600-13,900 BP in South America. For areas south of Beringia, these estimates correspond well with the first significant evidence for human presence and are consistent with the predictions of the overkill hypothesis.

Radiocarbon-based assessment of fossil fuel-derived contaminant associations in sediments.

PubMed

White, Helen K; Reddy, Christopher M; Eglinton, Timothy I

2008-08-01

Hydrophobic organic contaminants (HOCs) are associated with natural organic matter (OM) in the environment via mechanisms such as sorption or chemical binding. The latter interactions are difficult to quantitatively constrain, as HOCs can reside in different OM pools outside of conventional analytical windows. Here, we exploited natural abundance variations in radiocarbon (14C) to trace various fossil fuel-derived HOCs (14C-free) within chemically defined fractions of contemporary OM (modern 14C content) in 13 samples including marine and freshwater sediments and one dust and one soil sample. Samples were sequentially treated by solvent extraction followed by saponification. Radiocarbon analysis of the bulk sample and resulting residues was then performed. Fossil fuel-derived HOCs released by these treatments were quantified from an isotope mass balance approach as well as by gas chromatography-mass spectrometry. For the majority of samples (n = 13), 98-100% of the total HOC pool was solvent extractable. Nonextracted HOCs are only significant (29% of total HOC pool)in one sample containing p,p-2,2-bis(chlorophenyl)-1,1,1-trichloroethane and its metabolites. The infrequency of significant incorporation of HOCs into nonextracted OM residues suggests that most HOCs are mobile and bioavailable in the environment and, as such, have a greater potential to exert adverse effects.

Immunogenicity and safety of purified chick-embryo cell rabies vaccine under Zagreb 2-1-1 or 5-dose Essen regimen in Chinese children 6 to 17 years old and adults over 50 years: A randomized open-label study

PubMed Central

Li, RongCheng; Li, YanPing; Wen, ShuQing; Wen, HuiChun; Nong, Yi; Mo, Zhaojun; Xie, Fang; Pellegrini, Michele

2015-01-01

The aim of this Phase IIIb, open-label, randomized study was to demonstrate the non-inferiority of immune responses and to assess the safety of a purified chick-embryo cell rabies vaccine (PCECV) in healthy Chinese children (6 to 17 years) and older adults (≥51 years) following 2 alternative intramuscular (IM) simulated post-exposure prophylaxis (PEP) regimens: 4-dose Zagreb or 5-dose Essen regimen. Serum samples were collected prior to vaccination on Days 1 and 15 and on day 43 to assess immune response by rabies virus neutralizing antibody (RVNA) concentrations. Solicited adverse events (AEs) were recorded for up to 7 days following each vaccine dose, and unsolicited AEs throughout the entire study period. PCECV vaccination induced a strong immune response at Day 15, and the non-inferiority in immune response of the Zagreb vs. the Essen regimen was demonstrated in children and older adults. At Day 15,100% of children (N = 224), and 99% of subjects ≥51 years of age (N = 376) developed adequate RVNA concentrations (≥0.5 IU/mL); at Day 43 all subjects achieved RVNA concentrations ≥0.5 IU/mL, for both PEP regimens. The well-known tolerability and safety profile of the PCECV was again observed in this study following either Zagreb or Essen regimens. Rabies PEP vaccination with PCECV following a Zagreb regimen induced immune responses non-inferior to those of the Essen regimen, and had a similar safety and tolerability profile to the Essen regimen in Chinese children, adolescents, and adults over 51 years. ClinicalTrials.gov identifier: NCT01680016. PMID:25692350

African Baobabs with False Inner Cavities: The Radiocarbon Investigation of the Lebombo Eco Trail Baobab

PubMed Central

Patrut, Adrian; Woodborne, Stephan; von Reden, Karl F.; Hall, Grant; Hofmeyr, Michele; Lowy, Daniel A.; Patrut, Roxana T.

2015-01-01

The article reports the radiocarbon investigation results of the Lebombo Eco Trail tree, a representative African baobab from Mozambique. Several wood samples collected from the large inner cavity and from the outer part of the tree were investigated by AMS radiocarbon dating. According to dating results, the age values of all samples increase from the sampling point with the distance into the wood. For samples collected from the cavity walls, the increase of age values with the distance into the wood (up to a point of maximum age) represents a major anomaly. The only realistic explanation for this anomaly is that such inner cavities are, in fact, natural empty spaces between several fused stems disposed in a ring-shaped structure. We named them false cavities. Several important differences between normal cavities and false cavities are presented. Eventually, we dated other African baobabs with false inner cavities. We found that this new architecture enables baobabs to reach large sizes and old ages. The radiocarbon date of the oldest sample was 1425 ± 24 BP, which corresponds to a calibrated age of 1355 ± 15 yr. The dating results also show that the Lebombo baobab consists of five fused stems, with ages between 900 and 1400 years; these five stems build the complete ring. The ring and the false cavity closed 800–900 years ago. The results also indicate that the stems stopped growing toward the false cavity over the past 500 years. PMID:25621989

[VASCULITIDES IN CHILDHOOD: A RETROSPECTIVE STUDY IN A PERIOD FROM 2002 TO 2012 AT THE DEPARTMENT OF PAEDIATRICS, UNIVERSITY HOSPITAL CENTRE ZAGREB].

PubMed

Jelusić, Marija; Kostić, Lucija; Frković, Marijan; Davidović, Masa; Malcić, Ivan

2015-01-01

The aim of our study was to analyze clinical features, laboratory findings, treatment, course and outcome of different types of vasculitis in children. All children aged up to 18 years that have been diagnosed with a vasculitis disorder from 2002. to 2012. at the Department of Paediatric, University Hospital Centre Zagreb according to EULAR/PRES/PRINTO criteria were included in the study. Vasculitis was diagnosed in 180 children, 101 girls and 79 boys, mean age 7.19 ± 3.7 years, with an average follow-up of 5.58 ± 3.28 years. Most of the children (155 or 86%) were diagnosed with Henoch-Shönlein purpura (HSP), polyarteritis nodosa (PAN) was diagnosed in 6 children (3.3%), isolated cutaneous leukocytoclastic vasculitis in 5 (2.8%), Takayasu arteritis (TA) and Kawasaki disease in 2 (1.1%) respectively, hypocomplementemic urticarial vasculitis in one patient (0.5%) and other types of vasculitis in 10 (5.5%) patients (vasculitides in systemic connective tissue disorders in 7 and unclassified vasculitides in 3 patients). All patients had elevated inflammatory markers (C-reactive protein and erythrocyte sedimentation rate). Anti-neutrophil cytoplasmatic antibodies (ANCA) were positive only in one patient, suffering from microscopic polyangiitis. Treatment modality in most patients were NSAIDs, while children with kidney or gastrointestinal system affection were treated with glucocorticoids and/or immunosuppresive drugs. Biological therapy (anti-CD20, rituximab) was used in patients with most severe symptoms. One child (0.56%), suffering from microscopic polyangiitis, died due to kidney failure during the follow-up. Forty patients (22.6%) had one disease relapse, while 6 (3.4%) had two relapses. In conclusion, we found some differences in laboratory parameters (e.g. lower incidence of elevated antistreptolysin O titer in HSP) and epidemiological data (e.g. higher prevalence of PAN in female children) in comparison to data from available studies, while other clinical

Radiocarbon signal of a low and intermediate level radioactive waste disposal facility in nearby trees.

PubMed

Janovics, R; Kelemen, D I; Kern, Z; Kapitány, S; Veres, M; Jull, A J T; Molnár, M

2016-03-01

Tree ring series were collected from the vicinity of a Hungarian radioactive waste treatment and disposal facility and from a distant control background site, which is not influenced by the radiocarbon discharge of the disposal facility but it represents the natural regional (14)C level. The (14)C concentration of the cellulose content of tree rings was measured by AMS. Data of the tree ring series from the disposal facility was compared to the control site for each year. The results were also compared to the (14)C data of the atmospheric (14)C monitoring stations at the disposal facility and to international background measurements. On the basis of the results, the excess radiocarbon of the disposal facility can unambiguously be detected in the tree from the repository site. Copyright © 2016 Elsevier Ltd. All rights reserved.

New radiocarbon dates for terminal Pleistocene and early Holocene settlements in West Turkana, northern Kenya

NASA Astrophysics Data System (ADS)

Beyin, Amanuel; Prendergast, Mary E.; Grillo, Katherine M.; Wang, Hong

2017-07-01

The Turkana Basin in northern Kenya is located in an environmentally sensitive region along the eastern African Rift system. Lake Turkana's sensitivity to fluctuations in precipitation makes this an ideal place to study prehistoric human adaptations during key climatic transitions. Here we present eleven radiocarbon dates from two recently excavated sites in West Turkana, Kokito 01 and Kokito 02. The sites span the Pleistocene-Holocene transition, a time of fluctuating lake levels and novel cultural responses within the region. Several scenarios are laid out for the interpretation of site chronologies, and these are discussed with reference to the terminal Pleistocene and early Holocene chronological record for the region. Given the paucity of well-dated sites from this timespan in the Turkana Basin, the new radiocarbon dates are an important step toward establishing human settlement history and associated cultural developments in the region.

Radiocarbon and stable-isotope geochemistry of organic and inorganic carbon in Lake Superior

NASA Astrophysics Data System (ADS)

Zigah, Prosper K.; Minor, Elizabeth C.; Werne, Josef P.

2012-03-01

We present a lake-wide investigation of Lake Superior carbon and organic matter biogeochemistry using radiocarbon, stable isotope, and carbon concentrations. Dissolved inorganic carbon (DIC) abundance in the lake was 121-122 Tg C, with offshore concentration andδ13C values being laterally homogenous and tightly coupled to the physical and thermal regime and biochemical processes. Offshore Δ14C of DIC (50-65‰) exhibited lateral homogeneity and was more 14C enriched than co-occurring atmospheric CO2 (˜38‰); nearshore Δ14C of DIC (36-38‰) was similar to atmospheric CO2. Dissolved organic carbon (DOC) abundance was 14.2-16.4 Tg C. DOC's concentration and δ13C were homogenous in June (mixed lake), but varied laterally during August (stratification) possibly due to spatial differences in lake productivity. Throughout sampling, DOC had modern radiocarbon values (14-58‰) indicating a semilabile nature with a turnover time of ≤60 years. Lake particulate organic carbon (POC, 0.9-1.3 Tg C) was consistently 13C depleted relative to DOC. The δ15N of epilimnetic particulate organic nitrogen shifted to more negative values during stratification possibly indicating greater use of nitrate (rather than ammonium) by phytoplankton in August. POC's radiocarbon was spatially heterogeneous (Δ14C range: 58‰ to -303‰), and generally 14C depleted relative to DOC and DIC. POC 14C depletion could not be accounted for by black carbon in the lake but, because of its spatial and temporal distribution, is attributed to sediment resuspension. The presence of old POC within the epilimnion of the open lake indicates possible benthic-pelagic coupling in the lake's organic carbon cycle; the ultimate fate of this old POC bears further investigation.

A portable molecular-sieve-based CO{sub 2} sampling system for radiocarbon measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palonen, V., E-mail: vesa.palonen@helsinki.fi

We have developed a field-capable sampling system for the collection of CO{sub 2} samples for radiocarbon-concentration measurements. Most target systems in environmental research are limited in volume and CO{sub 2} concentration, making conventional flask sampling hard or impossible for radiocarbon studies. The present system captures the CO{sub 2} selectively to cartridges containing 13X molecular sieve material. The sampling does not introduce significant under-pressures or significant losses of moisture to the target system, making it suitable for most environmental targets. The system also incorporates a significantly larger sieve container for the removal of CO{sub 2} from chambers prior to the CO{submore » 2} build-up phase and sampling. In addition, both the CO{sub 2} and H{sub 2}O content of the sample gas are measured continuously. This enables in situ estimation of the amount of collected CO{sub 2} and the determination of CO{sub 2} flux to a chamber. The portable sampling system is described in detail and tests for the reliability of the method are presented.« less

Cosmic ray event in 994 C.E. recorded in radiocarbon from Danish oak

NASA Astrophysics Data System (ADS)

Fogtmann-Schulz, A.; Østbø, S. M.; Nielsen, S. G. B.; Olsen, J.; Karoff, C.; Knudsen, M. F.

2017-08-01

We present measurements of radiocarbon in annual tree rings from the time period 980-1006 Common Era (C.E.), hereby covering the cosmic ray event in 994 C.E. The new radiocarbon record from Danish oak is based on both earlywood and latewood fractions of the tree rings, which makes it possible to study seasonal variations in 14C production. The measurements show a rapid increase of ˜10‰ from 993 to 994 C.E. in latewood, followed by a modest decline and relatively high values over the ensuing ˜10 years. This rapid increase occurs from 994 to 995 C.E. in earlywood, suggesting that the cosmic ray event most likely occurred during the period between April and June 994 C.E. Our new record from Danish oak shows strong agreement with existing Δ14C records from Japan, thus supporting the hypothesis that the 994 C.E. cosmic ray event was uniform throughout the Northern Hemisphere and therefore can be used as an astrochronological tie point to anchor floating chronologies of ancient history.

Fifty-five years (1955-2010) of the Coagulation Section at Laboratory of Hematology, Sestre milosrdnice University Hospital, and its founder, hematologist Ljubomir Popović.

PubMed

Stancić, Vladimir; Stancić, Nevenka; Vucelić, Vesna; Lang, Nada; Grbac, Ljiljana

2011-09-01

The Coagulation Section at Laboratory of Hematology, Sestre milosrdnice University Hospital, Zagreb, was founded in 1955 by Ljubomir Popović, hematologist and assistant at School of Medicine, University of Zagreb, in cooperation with hard-working laboratory technicians. Apart from papers on hematologic neoplasms, plasmacytoma and lymphoma, Ljubomir Popović published a number of papers in the field of anticoagulant therapy with heparin and oral anticoagulants, some of which are also in use today. After Ljubomir Popović left the Hospital in 1964, the Laboratory was run by Professor Nedjeljko Milić, head of the newly founded Division of Hematology. In 1968, the management of the Laboratory of Hematology was taken over by Biserka Raić, MS, medical biochemist, until her retirement in 2007. Great development in morphological and cytometric studies of blood and blood cells has been paralleled by continuous progress and almost dominating activities in the diagnosis of hemostasis disorders. In the 1970s, Marko Koprcina, hematologist, and Biserka Raić introduced the then latest tests in practice at all Hospital departments. In that golden age of the Coagulation Section, M. Koprcina, B. Raić and their associates transferred their knowledge to all colleagues in the Hospital. Through that collaboration, high standards in the diagnosis of hemostasis disorders were achieved, from which the currently high level of clinical knowledge about coagulation disorders and their treatment has derived, making Sestre milosrdnice University Hospital one of the leading hospitals in this field in the country. By describing development of the Coagulation Section and the life of its founder Ljubomir Popović, the authors tried to provide an answer to the following question: can today's clinicians still have a deciding role in laboratory development, considering that assessments of different phenomena are always initiated by an interested clinician who is trying to interpret and understand

THE INCIDENCE OF JACKAL BITES AND INJURIES IN THE ZAGREB ANTI RABIES CLINIC DURING THE 1995-2014 PERIOD.

PubMed

Vodopija, Radovan; Racz, Aleksandar; Pahor, Đana

2016-03-01

Rabies is a zoonotic disease (a disease transmitted to humans from animals) that is caused by a virus. The disease affects domestic and wild animals, and is spread to people through close contact with infectious material, usually saliva, via bites or scratches. Rabies is present on all continents with the exception of Antarctica, but more than 95% of human deaths occur in Asia and Africa. Once the symptoms of the disease have developed, rabies is nearly always fatal. People are usually infected following deep bite or scratch by an infected animal. Dogs are the main host and transmitter of rabies. They are the source of infection in all of the estimated 55 000 human rabies deaths annually in Asia and Africa. Bats are the source of most human rabies deaths in the Americas. Bat rabies has also recently emerged as a public health threat in Australia and Western Europe. Human deaths following exposure to foxes, raccoons, skunks, jackals, mongooses and other wild carnivore host species are very rare. In the Zagreb Anti Rabies Clinic, from 1995 to 2014, there were 18,094 patients bitten by various animals, but only 2 cases were caused by jackals. One was imported (from France), and the other was from Croatia. The incidence of jackal injuries during the observed period was extremely low, accounting for 0.011% of all animals. When the imported case is excluded, the incidence was 0.0055%. Accordingly, it is concluded that jackal bites and injuries are exceptionally low and that they pose no risk for patients who present routinely to the Zagreb Anti Rabies Clinic. Therefore, it is justified that jackal as an animal species be classified in the group of 'other animals', when officially reported.

Millennial-scale variability in the local radiocarbon reservoir age of south Florida during the Holocene

USGS Publications Warehouse

Toth, Lauren T.; Cheng, Hai; Edwards, R. Lawrence; Ashe, Erica; Richey, Julie N.

2017-01-01

A growing body of research suggests that the marine environments of south Florida provide a critical link between the tropical and high-latitude Atlantic. Changes in the characteristics of water masses off south Florida may therefore have important implications for our understanding of climatic and oceanographic variability over a broad spatial scale; however, the sources of variability within this oceanic corridor remain poorly understood. Measurements of ΔR, the local offset of the radiocarbon reservoir age, from shallow-water marine environments can serve as a powerful tracer of water-mass sources that can be used to reconstruct variability in local-to regional-scale oceanography and hydrology. We combined radiocarbon and U-series measurements of Holocene-aged corals from the shallow-water environments of the Florida Keys reef tract (FKRT) with robust statistical modeling to quantify the millennial-scale variability in ΔR at locations with (“nearshore”) and without (“open ocean”) substantial terrestrial influence. Our reconstructions demonstrate that there was significant spatial and temporal variability in ΔR on the FKRT during the Holocene. Whereas ΔR was similar throughout the region after ∼4000 years ago, nearshore ΔR was significantly higher than in the open ocean during the middle Holocene. We suggest that the elevated nearshore ΔR from ∼8000 to 5000 years ago was most likely the result of greater groundwater influence associated with lower sea level at this time. In the open ocean, which would have been isolated from the influence of groundwater, ΔR was lowest ∼7000 years ago, and was highest ∼3000 years ago. We evaluated our open-ocean model of ΔR variability against records of local-to regional-scale oceanography and conclude that local upwelling was not a significant driver of open-ocean radiocarbon variability in this region. Instead, the millennial-scale trends in open-ocean ΔR were more likely a result of broader

Marine04 Marine radiocarbon age calibration, 26 ? 0 ka BP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hughen, K; Baille, M; Bard, E

2004-11-01

New radiocarbon calibration curves, IntCal04 and Marine04, have been constructed and internationally ratified to replace the terrestrial and marine components of IntCal98. The new calibration datasets extend an additional 2000 years, from 0-26 ka cal BP (Before Present, 0 cal BP = AD 1950), and provide much higher resolution, greater precision and more detailed structure than IntCal98. For the Marine04 curve, dendrochronologically dated tree-ring samples, converted with a box-diffusion model to marine mixed-layer ages, cover the period from 0-10.5 ka cal BP. Beyond 10.5 ka cal BP, high-resolution marine data become available from foraminifera in varved sediments and U/Th-dated corals.more » The marine records are corrected with site-specific {sup 14}C reservoir age information to provide a single global marine mixed-layer calibration from 10.5-26.0 ka cal BP. A substantial enhancement relative to IntCal98 is the introduction of a random walk model, which takes into account the uncertainty in both the calendar age and the radiocarbon age to calculate the underlying calibration curve. The marine datasets and calibration curve for marine samples from the surface mixed layer (Marine04) are discussed here. The tree-ring datasets, sources of uncertainty, and regional offsets are presented in detail in a companion paper by Reimer et al.« less

Chronostratigraphy of a salt marsh sediment core from North Cinder Island in the Town of Hempstead, Long Island, NY, using radiocarbon and pollen

NASA Astrophysics Data System (ADS)

Farmer, E. C.; Browne, J.; Peteet, D. M.; Cochran, K. K.; Heilbrun, C.; Chery, N.; LongJohn, T.; Mayo, J.; Ricigliano, V.

2016-12-01

A 122 cm long sediment core was collected from the salt marsh of North Cinder Island (73.6092W, 40.6097N), a small uninhabited island in Middle Bay between Oceanside and Point Lookout, in the Town of Hempstead, NY, on 2 July 2013, in order to investigate the age of the marsh and the history of trace metal pollution in the area. First, to determine the chronostratigraphy of the core, pollen counts were compared to radiocarbon measurements. Sediment samples at several depths in the core were analyzed for Pine, Oak, Hickory, Birch, Grass (S. alterniflora and S. patens), and Ragweed pollen. The concentration of Ragweed was below 3% in samples below 80cm, and greater than 7% in samples above 80cm. This proliferation of a disturbance species suggests that layers deeper than 81cm were deposited prior to widespread European settlement, sometime in the 1600s AD. Paired radiocarbon measurements on sieved fine sediment at 42-43 cm depth, however, match well with each other (their 1-sigma confidence intervals overlap), but suggest a calendar age between 932 and 997 years before present. Paired radiocarbon measurements from the 60-61 cm depth also match well with each other, but represent an age that is approximately 200 years younger. Additional paired radiocarbon measurements at 78-79 cm and 96-97 cm depths give older ages, as expected stratigraphically. Perhaps the reversal between 43 and 60 cm represents reworking of sediments in the marsh by tidal currents. Interestingly, root matter extracted from the sediment at the same depths gives radiocarbon ages that range from 600-1200 years younger. Perhaps the roots penetrate down through older sediment, or perhaps the fine sediment is comprised of recaptured sediment with lignin or other residual organic matter that is older because it is difficult to break down. This would explain the apparent contradiction between the radiocarbon dates on fine sediment and the younger pollen date at a deeper depth.

Radiocarbon dating late Quaternary loess deposits using small terrestrial gastropod shells

USGS Publications Warehouse

Pigati, Jeff S.; McGeehin, John P.; Muhs, Daniel R.; Bettis, E. Arthur

2013-01-01

Constraining the ages and mass accumulation rates of late Quaternary loess deposits is often difficult because of the paucity of organic material typically available for 14C dating and the inherent limitations of luminescence techniques. Radiocarbon dating of small terrestrial gastropod shells may provide an alternative to these methods as fossil shells are common in loess and contain ∼12% carbon by weight. Terrestrial gastropod assemblages in loess have been used extensively to reconstruct past environmental conditions but have been largely ignored for dating purposes. Here, we present the results of a multi-faceted approach to understanding the potential for using small terrestrial gastropod shells to date loess deposits in North America. First, we compare highly resolved 14C ages of well-preserved wood and gastropod shells (Succineidae) recovered from a Holocene loess section in Alaska. Radiocarbon ages derived from the shells are nearly identical to wood and plant macrofossil ages throughout the section, which suggests that the shells behaved as closed systems with respect to carbon for at least the last 10 ka (thousands of calibrated 14C years before present). Second, we apply 14C dating of gastropod shells to late Pleistocene loess deposits in the Great Plains using stratigraphy and independent chronologies for comparison. The new shell ages require less interpretation than humic acid radiocarbon ages that are commonly used in loess studies, provide additional stratigraphic coverage to previous dating efforts, and are in correct stratigraphic order more often than their luminescence counterparts. Third, we show that Succineidae shells recovered from historic loess in the Matanuska River Valley, Alaska captured the 20th century 14C bomb spike, which suggests that the shells can be used to date late Holocene and historic-aged loess. Finally, results from Nebraska and western Iowa suggest that, similar to other materials, shell ages approaching ∼40 ka should

Insights into soil carbon dynamics across climatic gradients from carbon-pool specific radiocarbon analyses

NASA Astrophysics Data System (ADS)

van der Voort, Tessa Sophia; Hagedorn, Frank; McIntyre, Cameron; Zell, Claudia; Eglinton, Timothy Ian

2017-04-01

Soil carbon constitutes the largest terrestrial reservoir of organic carbon, and therefore understanding the mechanisms and drivers of carbon stabilization is crucial, especially in the framework of climate change. The understanding of the dependence of soil organic turnover in specific carbon pools as related to e.g. climate, soil texture and mineralogy is limited. In this framework, radiocarbon constitutes a uniquely powerful tool that help to unravel carbon dynamics from decadal to millennial timescales. This project combines bulk and pool-specific radiocarbon analyses in the top and deep soil on a wide range of forested soils that span a large climatic gradient (MAT 1.3-9.2°C, MAP 600 to 2100 mm m-2y-1). These well-studies sites are part of the Long-Term Forest Ecosystem Research (LWF) program of the Swiss Federal Institute for Forest, Snow and Landscape research (WSL). This study aims to combine the insights gained from bulk and pool-specific turnover to environmental conditions and molecular composition of soil carbon. The pools investigated span the mineral-associated (occluded and heavy fractions from density fractionation) and potentially water-soluble (free light fractions from density fractionation and water extractable organic carbon) organic carbon fractions. Pool-specific radiocarbon work is augmented by the measurement of abundance of compounds such as alkanes, fatty acids and lignin phenols on a subset of samples. Initial results show disparate patterns depending on soil type and in particular soil texture, which could be indicative of various stabilization mechanisms in different soils. Overall, this study provides new insights into the controls of soil organic matter dynamics as related to environmental conditions, in particular in specific sub-pools of carbon.

Intercomparison of radiocarbon bomb pulse and 210Pb age models. A study in a peat bog core from North Poland

NASA Astrophysics Data System (ADS)

Piotrowska, Natalia; De Vleeschouwer, François; Sikorski, Jarosław; Pawlyta, Jacek; Fagel, Nathalie; Le Roux, Gaël; Pazdur, Anna

2010-04-01

Radiocarbon and 210Pb were measured on the uppermost 40 cm of a Wardenaar peat core retrieved from a Baltic raised bog at Słowińskie Błota (Pomerania, North Poland). This site is the subject of ongoing multiproxy studies covering the last 1300 years. Radiocarbon age model was constructed on the basis of 14 AMS dates obtained on selected Sphagnum spp. fragments, with use of P_Sequence tool. We present here a comparison of this model with the age model obtained using CRS model classically applied to 210Pb measurements.

Reassessment of the 13C/12C and 14C/12C isotopic fractionation ratio and its impact on high-precision radiocarbon dating

NASA Astrophysics Data System (ADS)

Fahrni, Simon M.; Southon, John R.; Santos, Guaciara M.; Palstra, Sanne W. L.; Meijer, Harro A. J.; Xu, Xiaomei

2017-09-01

The vast majority of radiocarbon measurement results (14C/12C isotopic ratios or sample activities) are corrected for isotopic fractionation processes (measured as 13C/12C isotopic ratios) that occur in nature, in sample preparation and measurement. In 1954 Harmon Craig suggested a value of 2.0 for the fractionation ratio b that is used to correct 14C/12C ratios for shifts in the 13C/12C ratios and this value has been applied by the radiocarbon community ever since. While theoretical considerations suggest moderate deviations of b from 2.0, some measurements have suggested larger differences (e.g. b = 2.3, measured by Saliège and Fontes in 1984). With the high precision attained in radiocarbon measurements today (±2‰), even a relatively small deviation of b from 2.0 can impact the accuracy of radiocarbon data, and it is, therefore, of interest to re-evaluate the fractionation corrections. In the present study, the fractionation ratio b was determined by independent experiments on the chemical reduction of carbon dioxide (CO2) to elemental carbon (graphitization reaction) and on the photosynthetic uptake of CO2 by C3 and C4 plants. The results yielded b = 1.882 ± 0.019 for the reduction of CO2 to solid graphite and b = 1.953 ± 0.025 for the weighted mean of measurements involving C3 and C4 photosynthesis pathways. In addition, the analysis of over 9600 full-sized OX-I and OX-II normalizing standards measured between 2002 and 2012 confirms b values lower than 2.0. The obtained values are in good agreement with quantum mechanical estimates of the equilibrium fractionation and classic kinetic fractionation as well as with results from other light three-isotope systems (oxygen, magnesium, silicon and sulfur). While the value of the fractionation ratio varies with the relative importance of kinetic and equilibrium fractionation, the values obtained in the present study cluster around b = 1.9. Our findings suggest that a significant fraction of all samples

Attitudes towards and knowledge about homosexuality among medical students in Zagreb.

PubMed

Grabovac, Igor; Abramović, Marija; Komlenović, Gordana; Milosević, Milan; Mustajbegović, Jadranka

2014-03-01

The aim of the study was to investigate whether students in their fifth and sixth years of medical school in Zagreb have homophobic attitudes and assess their knowledge about homosexuality. A survey was conducted among fifth and sixth year medical students during the 2009/2010 academic year. The survey consisted of general demographic data, two validated questionnaires--"Knowledge about Homosexuality Questionnaire" and "Heterosexual Attitudes towards Homosexuality Scale"--and questions about personal experiences created for this study. The mean knowledge scores were X = 14.8 out of 20. Furthermore, gender differences in attitudes were observed, indicating less negative attitudes among the female participants. The regression model was significant (ANOVA: Sum of Squares = 38.065; df = 17, Mean Square= 2239, F = 10.6; p < 0.001) with 38% of explained variance. The significant predictor variables that indicate lower attitudes about homosexuality score were female gender (beta= -0.14, p = 0.015), sixth year of study (beta = -0.16, p = 0.009) and more knowledge about homosexuality (beta = -0.48, p < 0.001). Negative attitudes are present among the students; therefore, educational efforts should be included in the curricula of medical schools to diminish the negative perceptions of the lesbian, gay, bisexual and transgender community.

Collaboration, campaigns and champions for appropriate imaging: feedback from the Zagreb workshop.

PubMed

Remedios, D; Brkljacic, B; Ebdon-Jackson, S; Hierath, M; Sinitsyn, V; Vassileva, J

2018-04-01

Leading radiologists and representatives from national radiation protection regulatory authorities and health ministries from 19 countries of the European region worked together with five experts at the workshop on justification and appropriate use of imaging in Zagreb, Croatia, from 26 to 28 October 2017 jointly organised by the IAEA and the European Society of Radiology. The workshop served as a forum to exchange information on challenges and solutions for improving justification and the appropriate use of diagnostic imaging. Common barriers to improving the use of imaging referral guidelines were discussed and the need for increased collaboration identified. Examples of good practices were presented, including use of Clinical Decision Support (CDS) systems to facilitate rapid and good justification decisions. The workshop identified some of the needs of European countries for achieving more appropriate imaging proposing wider use of collaboration, campaigns and champions. • Drivers for appropriate imaging in Europe are similar to those elsewhere globally. • Implementing imaging referral guidelines is the main barrier to more appropriate imaging. • Clinical Decision Support systems (CDS) facilitates good referral practice and justification decisions. • Collaboration, campaigns and champions may improve awareness, appropriateness and audit.

Evolution of size-specific foraminiferal assemblages and the consequences for radiocarbon dating in bioturbated sediment

NASA Astrophysics Data System (ADS)

Costa, K.; Faith, E. S.; McManus, J. F.

2017-12-01

Deep-sea sediment mixing by bioturbation is ubiquitous on the seafloor, and it can be an important influence on the fidelity of paleoceanographic records. Bioturbation can be difficult to quantify, especially in the past, but diffusive models based on radioactive tracer profiles have provided a relatively successful approach. Stable isotope and radiocarbon data from five different foraminiferal species from sediment on the Juan de Fuca Ridge, Northeast Pacific, have previously identified age plateaus that correspond to peak foraminiferal abundances, related to assemblage shifts and carbonate preservation changes since the last glacial period. Here we present size-specific foraminiferal assemblages and over 100 radiocarbon dates to better constrain the effects of bioturbation on fossil chronometers. N. pachyderma is the dominant species in the 150-212µm while G. bulloides is the dominant species in all other size fractions (212-250 µm, 250-300 µm, 300-355 µm). The foraminiferal assemblage of 212-300 µm is found to be representative of the entire adult foraminiferal population >150 µm. Size-specific radiocarbon analyses on G. bulloides demonstrate that larger specimens are generally younger than smaller specimens, but all sizes are susceptible to abundance peak age plateaus. The young bias towards larger specimens may reflect their greater susceptibility to fragmentation during prolonged bioturbation, so that the influence of abundance peaks is shorter-lived in these size fractions. When foraminiferal abundance peaks are unavoidable, e.g. due to large shifts in carbonate preservation, we suggest that larger foraminiferal may provide a more accurate chronometer for sediment age.

Santorini eruption radiocarbon dated to 1627-1600 B.C.

PubMed

Friedrich, Walter L; Kromer, Bernd; Friedrich, Michael; Heinemeier, Jan; Pfeiffer, Tom; Talamo, Sahra

2006-04-28

Precise and direct dating of the Minoan eruption of Santorini (Thera) in Greece, a global Bronze Age time marker, has been made possible by the unique find of an olive tree, buried alive in life position by the tephra (pumice and ashes) on Santorini. We applied so-called radiocarbon wiggle-matching to a carbon-14 sequence of tree-ring segments to constrain the eruption date to the range 1627-1600 B.C. with 95.4% probability. Our result is in the range of previous, less precise, and less direct results of several scientific dating methods, but it is a century earlier than the date derived from traditional Egyptian chronologies.

A novel tertiary prep-HPLC method for the isolation of single amino acids for AMS-radiocarbon measurement.

PubMed

Fernandes, Ricardo; Koudelka, Tomas; Tholey, Andreas; Dreves, Alexander

2017-07-15

AMS-radiocarbon measurements of amino acids can potentially provide more reliable radiocarbon dates than bulk collagen analysis. Nonetheless, the applicability of such an approach is often limited by the low-throughput of existing isolation methods and difficulties in determining the contamination introduced during the separation process. A novel tertiary prep-HPLC amino acid isolation method was developed that relies on the combustion of eluted material without requiring any additional chemical steps. Amino acid separation was carried out using a gradient mix of pure water and phosphoric acid with an acetonitrile step in-between runs to remove hydrophobic molecules from the separation column. The amount of contaminant carbon and its 14 C content were determined from two-point measurements of collagen samples of known 14 C content. The amount of foreign carbon due to the isolation process was estimated at 4±1μg and its 14 C content was 0.43±0.01 F 14 C. Radiocarbon values corrected for carbon contamination have only a minor increase in uncertainties. For Holocene samples, this corresponds to an added uncertainty typically smaller than 10 14 Cyears. The developed method can be added to routine AMS measurements without implying significant operational changes and offers a level of measurement uncertainty that is suitable for many archaeological, ecological, environmental, and biological applications. Copyright © 2017. Published by Elsevier B.V.

50(th) Anniversary of the Central Dental Library of School of Dental Medicine University of Zagreb.

PubMed

Borić, Vesna

2014-12-01

Libraries have an exceptional place in the history, culture, education and scientific life of a nation. They collect all aspects of our linguistics and literacy, all out theoretical assumptions as well as all the results of experience and practice. The importance of a library is not mirrored only in the national and historical role and heritage, but in a more permanent, informational role, since a modern library must, above all, be an effective information system. Since a library of a university operates as a part of its matrix, it is easily shadowed by other forms of educational and scientific infrastructure. 50(th) anniversary of the Central Dental Library of the School of Dental Medicine University of Zagreb is an excellent opportunity to make a call to the institution and public to its unique and irreplaceable role.

Rewriting the Central European Early Bronze Age Chronology: Evidence from Large-Scale Radiocarbon Dating

PubMed Central

Knipper, Corina; Friedrich, Ronny; Kromer, Bernd; Lindauer, Susanne; Radosavljević, Jelena; Wittenborn, Fabian; Krause, Johannes

2015-01-01

The transition from the Neolithic to the Early Bronze Age in Central Europe has often been considered as a supra-regional uniform process, which led to the growing mastery of the new bronze technology. Since the 1920s, archaeologists have divided the Early Bronze Age into two chronological phases (Bronze A1 and A2), which were also seen as stages of technical progress. On the basis of the early radiocarbon dates from the cemetery of Singen, southern Germany, the beginning of the Early Bronze Age in Central Europe was originally dated around 2300/2200 BC and the transition to more complex casting techniques (i.e., Bronze A2) around 2000 BC. On the basis of 140 newly radiocarbon dated human remains from Final Neolithic, Early and Middle Bronze Age cemeteries south of Augsburg (Bavaria) and a re-dating of ten graves from the cemetery of Singen, we propose a significantly different dating range, which forces us to re-think the traditional relative and absolute chronologies as well as the narrative of technical development. We are now able to date the beginning of the Early Bronze Age to around 2150 BC and its end to around 1700 BC. Moreover, there is no transition between Bronze (Bz) A1 and Bronze (Bz) A2, but a complete overlap between the type objects of the two phases from 1900–1700 BC. We thus present a revised chronology of the assumed diagnostic type objects of the Early Bronze Age and recommend a radiocarbon-based view on the development of the material culture. Finally, we propose that the traditional phases Bz A1 and Bz A2 do not represent a chronological sequence, but regionally different social phenomena connected to the willingness of local actors to appropriate the new bronze technology. PMID:26488413

On the radiocarbon record in banded corals: exchange parameters and net transport of /sup 14/CO/sub 2/ between atmosphere and surface ocean

DOE Office of Scientific and Technical Information (OSTI.GOV)

Druffel, E.M.; Suess, H.E.

1983-02-20

We have made radiocarbon measurements of banded hermatypic corals from Florida, Belize, and the Galapagos Islands. Interpretation is presented here of these previously reported results. These measurements represent the /sup 14/C//sup 12/C ratios in dissolved inorganic carbon (DIOC) in the surface ocean waters of the Gulf Stream and the Peru Current at the time of coral ring formation. A depletion in radiocarbon concentration was observed incoral rings that grew from A.D. 1900--1952. It was caused by dilution of existing /sup 14/C levels with dead CO/sub 2/ from fossil fuel burning (the Suess effect, or S/sub e/). A similar trend wasmore » observed in the distribution of bomb-produced /sup 14/C in corals that had grown during the years following A.D. 1952. The concentration of bomb-produced radiocarbon was much higher in corals from temperate regions (Florida, Belize, Hawaiian Islands) than in corals from tropical regions (Galapagos Islands and Canton Island). The apparent radiocarbon ages of the surface waters in temperate and tropical oceans during the preanthropogenic period range from about 280 to 520 years B.P. (-40 to -69%). At all investigated locations, it is likely that waters at subsurface depths have the same apparent radiocarbon age of about 670 years B.P. From the change of oceanic ..delta../sup 14/C in the surface during post-bomb times, the approximate annual rate of net input of /sup 14/CO/sub 2/ to the ocean waters is calculated to be about 8% of the prevailing /sup 14/C difference between atmosphere and ocean. From this input and from preanthropogenic ..delta../sup 14/C values found at each location, it can be seen that vertical mixing of water in the Peru Current is about 3 times greater than that in the Gulf Stream.« less

Single ion hit detection set-up for the Zagreb ion microprobe

NASA Astrophysics Data System (ADS)

Smith, R. W.; Karlušić, M.; Jakšić, M.

2012-04-01

Irradiation of materials by heavy ions accelerated in MV tandem accelerators may lead to the production of latent ion tracks in many insulators and semiconductors. If irradiation is performed in a high resolution microprobe facility, ion tracks can be ordered by submicrometer positioning precision. However, full control of the ion track positioning can only be achieved by a reliable ion hit detection system that should provide a trigger signal irrespectively of the type and thickness of the material being irradiated. The most useful process that can be utilised for this purpose is emission of secondary electrons from the sample surface that follows the ion impact. The status report of the set-up presented here is based on the use of a channel electron multiplier (CEM) detector mounted on an interchangable sample holder that is inserted into the chamber in a close geometry along with the sample to be irradiated. The set-up has been tested at the Zagreb ion microprobe for different ions and energies, as well as different geometrical arrangements. For energies of heavy ions below 1 MeV/amu, results show that efficient (100%) control of ion impact can be achieved only for ions heavier than silicon. The successful use of the set-up is demonstrated by production of ordered single ion tracks in a polycarbonate film and by monitoring fluence during ion microbeam patterning of Foturan glass.

Radiocarbon dating of American pika fecal pellets provides insights into population extirpations and climate refugia

Treesearch

Constance I. Millar; Katherine Heckman; Christopher Swanston; Karena Schmidt; Robert D. Westfall; Diane L. Delany

2014-01-01

The American pika (Ochotona princeps) has become a species of concern for its sensitivity to warm temperatures and potential vulnerability to global warming. We explored the value of radiocarbon dating of fecal pellets to address questions of population persistence and timing of site extirpation. Carbon was extracted from pellets collected at 43...

Time in tortoiseshell: a bomb radiocarbon-validated chronology in sea turtle scutes.

PubMed

Van Houtan, Kyle S; Andrews, Allen H; Jones, T Todd; Murakawa, Shawn K K; Hagemann, Molly E

2016-01-13

Some of the most basic questions of sea turtle life history are also the most elusive. Many uncertainties surround lifespan, growth rates, maturity and spatial structure, yet these are critical factors in assessing population status. Here we examine the keratinized hard tissues of the hawksbill (Eretmochelys imbricata) carapace and use bomb radiocarbon dating to estimate growth and maturity. Scutes have an established dietary record, yet the large keratin deposits of hawksbills evoke a reliable chronology. We sectioned, polished and imaged posterior marginal scutes from 36 individual hawksbills representing all life stages, several Pacific populations and spanning eight decades. We counted the apparent growth lines, microsampled along growth contours and calibrated Δ(14)C values to reference coral series. We fit von Bertalanffy growth function (VBGF) models to the results, producing a range of age estimates for each turtle. We find Hawaii hawksbills deposit eight growth lines annually (range 5-14), with model ensembles producing a somatic growth parameter (k) of 0.13 (range 0.1-0.2) and first breeding at 29 years (range 23-36). Recent bomb radiocarbon values also suggest declining trophic status. Together, our results may reflect long-term changes in the benthic community structure of Hawaii reefs, and possibly shed light on the critical population status for Hawaii hawksbills. © 2016 The Author(s).

Time in tortoiseshell: a bomb radiocarbon-validated chronology in sea turtle scutes

PubMed Central

Van Houtan, Kyle S.; Andrews, Allen H.; Jones, T. Todd; Murakawa, Shawn K. K.; Hagemann, Molly E.

2016-01-01

Some of the most basic questions of sea turtle life history are also the most elusive. Many uncertainties surround lifespan, growth rates, maturity and spatial structure, yet these are critical factors in assessing population status. Here we examine the keratinized hard tissues of the hawksbill (Eretmochelys imbricata) carapace and use bomb radiocarbon dating to estimate growth and maturity. Scutes have an established dietary record, yet the large keratin deposits of hawksbills evoke a reliable chronology. We sectioned, polished and imaged posterior marginal scutes from 36 individual hawksbills representing all life stages, several Pacific populations and spanning eight decades. We counted the apparent growth lines, microsampled along growth contours and calibrated Δ14C values to reference coral series. We fit von Bertalanffy growth function (VBGF) models to the results, producing a range of age estimates for each turtle. We find Hawaii hawksbills deposit eight growth lines annually (range 5–14), with model ensembles producing a somatic growth parameter (k) of 0.13 (range 0.1–0.2) and first breeding at 29 years (range 23–36). Recent bomb radiocarbon values also suggest declining trophic status. Together, our results may reflect long-term changes in the benthic community structure of Hawaii reefs, and possibly shed light on the critical population status for Hawaii hawksbills. PMID:26740617

Frequency of tuberculosis at autopsies in a large hospital in Zagreb, Croatia: a 10-year retrospective study

PubMed Central

Pavić, Ivana; Radulović, Petra; Bujas, Tatjana; Perić Balja, Melita; Ostojić, Jelena; Baličević, Drinko

2012-01-01

Aim To assess the frequency and forms of pulmonary tuberculosis at autopsy in a high-traffic hospital in the capital city of a country with a low tuberculosis incidence. Methods We performed a retrospective search of autopsy data from the period 2000 to 2009 at Sestre Milosrdnice University Hospital Center, Zagreb, Croatia. We also examined patients’ records and histological slides. Results Of 3479 autopsies, we identified 61 tuberculosis cases, corresponding to a frequency of 1.8%. Active tuberculosis was found in 33 cases (54%), 23 of which (70%) were male. Of the 33 active cases, 25 (76%) were clinically unrecognized and 19 (76%) of these were male. Conclusion Clinically undiagnosed tuberculosis accounted for a substantial proportion of active tuberculosis cases diagnosed at autopsy. Autopsy data may be an important complement to epidemiological data on tuberculosis frequency. PMID:22351578

Dating of the Basal Aurignacian Sandwich at Abric Romanı́ (Catalunya, Spain) by Radiocarbon and Uranium-Series

USGS Publications Warehouse

Bischoff, James L.; Ludwig, Kenneth R.; Garcia, Jose Francisco; Carbonell, E.; Vaquero, Manola; Stafford, Thomas W.; Jull, A.J.T.

1994-01-01

Abric Romani{dotless}??, a rock shelter located near Barcelona, Spain, contains a charcoal-bearing basal Aurignacian occupation level sandwiched between beds of moss-generated carbonate. The Aurignacian culture is the oldest artefact industry in Europe with which anatomically modern human remains have been associated. Radiocarbon analysis of charcoal fragments by accelerator mass spectrometry (AMS) dates the basal Aurignacian to about 37 ?? 2 ka bp. U-series analyses by alpha spectrometry (AS) and mass spectrometry (MS) date the enclosing carbonate to 43 ?? 1 ka bp. These results confirm the great antiquity of the Aurignacian in northern Spain and support the similar AMS dates from El Castillo and l'Arbreda caves. They also show that radiocarbon dates are significantly younger than U-series at 40 ka bp, as predicted by theory. ?? 1994 Academic Press. All rights reserved.

Environmental tritium and radiocarbon studies in the Vedavati River basin, Karnataka and Andhra Pradesh, India

NASA Astrophysics Data System (ADS)

Sukhija, B. S.; Achutha Rao, A.

1983-01-01

Environmental tritium and radiocarbon studies were undertaken in the Vedavati river basin situated partly in Karnataka and partly in Andhra Pradesh, India, aimed at the determination of the general recharge condition of the water-bearing zones in the gneissic complex, granites and the Dharwar Group of metamorphic rocks, where groundwater occurs under semi-unconfined to semi-confined conditions and at places under the water-table condition. The groundwater movement is controlled by fractures, fissures, a weathered zone and surficial mantle. An attempt was also made to find out whether substantial recharge occurs along fractured lineaments; whether the water-bearing zones can be considered as interconnected or isolated, and whether the recharge and discharge areas identified by geohydrological considerations can be confirmed. Environmental tritium and radiocarbon contents, measured in ˜ 45 groundwater samples, show that a large number of samples are very young, containing water from post-thermonuclear-era rain, thus indicating an age less than 25 yr. In some other samples, despite radiocarbon ages found to be older, some component of recent precipitation is found to be present as indicated by bomb tritium. Groundwater dating in the area shows an excellent correlation between hydro-isochrons of minimum age with the recharge contour of maximum magnitude. This study has clearly resulted in the demarcation of the recharge areas. However, the discharge areas as such cannot be clearly delineated because of lack of a pattern indicating increase of ages in any particular direction. This, however, also reflects somewhat discontinuous groundwater bodies, which may also be expected from the general structure and hydrogeology of the region. Along a major lineament the groundwater is found to be very young thus confirming that substantial recharge occurs along lineaments.

Radiocarbon dating of American pika fecal pellets provides insights into population extirpations and climate refugia.

PubMed

Millar, Constance I; Heckman, Katherine; Swanston, Christopher; Schmidt, Karena; Westfall, Robert D; Delany, Diane L

The American pika (Ochotona princeps) has become a species of concern for its sensitivity to warm temperatures and potential vulnerability to global warming. We explored the value of radiocarbon dating of fecal pellets to address questions of population persistence and timing of site extirpation. Carbon was extracted from pellets collected at 43 locations in the western Great Basin, USA, including three known occupied sites and 40 sites of uncertain status at range margins or where previous studies indicated the species is vulnerable. We resolved calibrated dates with high precision (within several years), most of which fell in the period of the mid-late 20th century bomb curve. The two-sided nature of the bomb curve renders far- and near-side dates of equal probability, which are separated by one to four decades. We document methods for narrowing resolution to one age range, including stratigraphic analysis of vegetation collected from pika haypiles. No evidence was found for biases in atmospheric 14C levels due to fossil-derived or industrial CO2 contamination. Radiocarbon dating indicated that pellets can persist for >59 years; known occupied sites resolved contemporary dates. Using combined evidence from field observations and radiocarbon dating, and the Bodie Mountains as an example, we propose a historical biogeographic scenario for pikas in minor Great Basin mountain ranges adjacent to major cordillera, wherein historical climate variability led to cycles of extirpation and recolonization during alternating cool and warm centuries. Using this model to inform future dynamics for small ranges in biogeographic settings similar to the Bodie Mountains in California, extirpation of pikas appears highly likely under directional warming trends projected for the next century, even while populations in extensive cordillera (e.g., Sierra Nevada, Rocky Mountains, Cascade Range) are likely to remain viable due to extensive, diverse habitat and high connectivity.

High-precision radiocarbon dating shows recent and rapid initial human colonization of East Polynesia.

PubMed

Wilmshurst, Janet M; Hunt, Terry L; Lipo, Carl P; Anderson, Atholl J

2011-02-01

The 15 archipelagos of East Polynesia, including New Zealand, Hawaii, and Rapa Nui, were the last habitable places on earth colonized by prehistoric humans. The timing and pattern of this colonization event has been poorly resolved, with chronologies varying by >1000 y, precluding understanding of cultural change and ecological impacts on these pristine ecosystems. In a meta-analysis of 1,434 radiocarbon dates from the region, reliable short-lived samples reveal that the colonization of East Polynesia occurred in two distinct phases: earliest in the Society Islands A.D. ∼1025-1120, four centuries later than previously assumed; then after 70-265 y, dispersal continued in one major pulse to all remaining islands A.D. ∼1190-1290. We show that previously supported longer chronologies have relied upon radiocarbon-dated materials with large sources of error, making them unsuitable for precise dating of recent events. Our empirically based and dramatically shortened chronology for the colonization of East Polynesia resolves longstanding paradoxes and offers a robust explanation for the remarkable uniformity of East Polynesian culture, human biology, and language. Models of human colonization, ecological change and historical linguistics for the region now require substantial revision.

Searching for the oldest baobab of Madagascar: radiocarbon investigation of large Adansonia rubrostipa trees.

PubMed

Patrut, Adrian; von Reden, Karl F; Danthu, Pascal; Pock-Tsy, Jean-Michel Leong; Patrut, Roxana T; Lowy, Daniel A

2015-01-01

We extended our research on the architecture, growth and age of trees belonging to the genus Adansonia, by starting to investigate large individuals of the most widespread Malagasy species. Our research also intends to identify the oldest baobabs of Madagascar. Here we present results of the radiocarbon investigation of the two most representative Adansonia rubrostipa (fony baobab) specimens, which are located in south-western Madagascar, in the Tsimanampetsotse National Park. We found that the fony baobab called "Grandmother" consists of 3 perfectly fused stems of different ages. The radiocarbon date of the oldest sample was found to be 1136 ± 16 BP. We estimated that the oldest part of this tree, which is mainly hollow, has an age close to 1,600 yr. This value is comparable to the age of the oldest Adansonia digitata (African baobab) specimens. By its age, the Grandmother is a major candidate for the oldest baobab of Madagascar. The second investigated specimen, called the "polygamous baobab", consists of 6 partially fused stems of different ages. According to dating results, this fony baobab is 1,000 yr old. This research is the first investigation of the structure and age of Malagasy baobabs.

High-precision radiocarbon dating shows recent and rapid initial human colonization of East Polynesia

PubMed Central

Wilmshurst, Janet M.; Hunt, Terry L.; Lipo, Carl P.; Anderson, Atholl J.

2011-01-01

The 15 archipelagos of East Polynesia, including New Zealand, Hawaii, and Rapa Nui, were the last habitable places on earth colonized by prehistoric humans. The timing and pattern of this colonization event has been poorly resolved, with chronologies varying by >1000 y, precluding understanding of cultural change and ecological impacts on these pristine ecosystems. In a meta-analysis of 1,434 radiocarbon dates from the region, reliable short-lived samples reveal that the colonization of East Polynesia occurred in two distinct phases: earliest in the Society Islands A.D. ∼1025–1120, four centuries later than previously assumed; then after 70–265 y, dispersal continued in one major pulse to all remaining islands A.D. ∼1190–1290. We show that previously supported longer chronologies have relied upon radiocarbon-dated materials with large sources of error, making them unsuitable for precise dating of recent events. Our empirically based and dramatically shortened chronology for the colonization of East Polynesia resolves longstanding paradoxes and offers a robust explanation for the remarkable uniformity of East Polynesian culture, human biology, and language. Models of human colonization, ecological change and historical linguistics for the region now require substantial revision. PMID:21187404

Radiocarbon in CO2 and Soil Organic Matter from Laboratory Incubations, Barrow, Alaska, 2012

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lydia Vaughn; Margaret Torn

Dataset includes Delta14C measurements made from soil organic matter and CO2 from laboratory soil incubations of active layer soils collected in Barrow, Alaska in 2012. In addition to Delta14CO2, dataset CO2 production rates and carbon and nitrogen concentrations. Samples were collected from intensive study site 1 areas A, B, and C, and the site 0 and AB transects, from specified positions in high-centered, flat-centered, and low centered polygons.

Rapid isolation of biomarkers for compound specific radiocarbon dating using high-performance liquid chromatography and flow injection analysis-atmospheric pressure chemical ionisation mass spectrometry.

PubMed

Smittenberg, Rienk H; Hopmans, Ellen C; Schouten, Stefan; Sinninghe Damsté, Jaap S

2002-11-29

Repeated semi-preparative normal-phase HPLC was performed to isolate selected biomarkers from sediment extracts for radiocarbon analysis. Flow injection analysis-mass spectrometry was used for rapid analysis of collected fractions to evaluate the separation procedure, taking only 1 min per fraction. In this way 100-1000 microg of glycerol dialkyl glycerol tetraethers, sterol fractions and chlorophyll-derived phytol were isolated from typically 100 g of marine sediment, i.e., in sufficient quantities for radiocarbon analysis, without significant carbon isotopic fractionation or contamination.

Source apportionment of elevated wintertime PAHs by compound-specific radiocarbon analysis

NASA Astrophysics Data System (ADS)

Sheesley, R. J.; Kruså, M.; Krecl, P.; Johansson, C.; Gustafsson, Ã.-.

2009-05-01

Natural abundance radiocarbon analysis facilitates distinct source apportionment between contemporary biomass/biofuel (14C "alive") versus fossil fuel (14C "dead") combustion. Here, the first compound-specific radiocarbon analysis (CSRA) of atmospheric polycyclic aromatic hydrocarbons (PAHs) was demonstrated for a set of samples collected in Lycksele, Sweden a small town with frequent episodes of severe atmospheric pollution in the winter. Renewed interest in using residential wood combustion (RWC) means that this type of seasonal pollution is of increasing concern in many areas. Five individual/paired PAH isolates from three pooled fortnight-long filter collections were analyzed by CSRA: phenanthrene, fluoranthene, pyrene, benzo[b+k]fluoranthene and indeno[cd]pyrene plus benzo[ghi]perylene; phenanthrene was the only compound also analyzed in the gas phase. The measured Δ14C for PAHs spanned from -138.3‰ to 58.0‰. A simple isotopic mass balance model was applied to estimate the fraction biomass (fbiomass) contribution, which was constrained to 71-87% for the individual PAHs. Indeno[cd]pyrene plus benzo[ghi]perylene had an fbiomass of 71%, while fluoranthene and phenanthrene (gas phase) had the highest biomass contribution at 87%. The total organic carbon (TOC, defined as carbon remaining after removal of inorganic carbon) fbiomass was estimated to be 77%, which falls within the range for PAHs. This CSRA data of atmospheric PAHs established that RWC is the dominating source of atmospheric PAHs to this region of the boreal zone with some variations among RWC contributions to specific PAHs.

Quantifying archaeal community autotrophy in the mesopelagic ocean using natural radiocarbon

PubMed Central

Ingalls, Anitra E.; Shah, Sunita R.; Hansman, Roberta L.; Aluwihare, Lihini I.; Santos, Guaciara M.; Druffel, Ellen R. M.; Pearson, Ann

2006-01-01

An ammonia-oxidizing, carbon-fixing archaeon, Candidatus “Nitrosopumilus maritimus,” recently was isolated from a salt-water aquarium, definitively confirming that chemoautotrophy exists among the marine archaea. However, in other incubation studies, pelagic archaea also were capable of using organic carbon. It has remained unknown what fraction of the total marine archaeal community is autotrophic in situ. If archaea live primarily as autotrophs in the natural environment, a large ammonia-oxidizing population would play a significant role in marine nitrification. Here we use the natural distribution of radiocarbon in archaeal membrane lipids to quantify the bulk carbon metabolism of archaea at two depths in the subtropical North Pacific gyre. Our compound-specific radiocarbon data show that the archaea in surface waters incorporate modern carbon into their membrane lipids, and archaea at 670 m incorporate carbon that is slightly more isotopically enriched than inorganic carbon at the same depth. An isotopic mass balance model shows that the dominant metabolism at depth indeed is autotrophy (83%), whereas heterotrophic consumption of modern organic carbon accounts for the remainder of archaeal biomass. These results reflect the in situ production of the total community that produces tetraether lipids and are not subject to biases associated with incubation and/or culture experiments. The data suggest either that the marine archaeal community includes both autotrophs and heterotrophs or is a single population with a uniformly mixotrophic metabolism. The metabolic and phylogenetic diversity of the marine archaea warrants further exploration; these organisms may play a major role in the marine cycles of nitrogen and carbon. PMID:16614070

Radiocarbon dating of individual lignin phenols: a new approach for establishing chronology of late quaternary lake sediments.

PubMed

Hou, Juzhi; Huang, Yongsong; Brodsky, Corynn; Alexandre, Marcelo R; McNichol, Ann P; King, John W; Hu, Feng Sheng; Shen, Ji

2010-09-01

The reliability of chronology is a prerequisite for meaningful paleoclimate reconstructions from sedimentary archives. The conventional approach of radiocarbon dating bulk organic carbon in lake sediments is often hampered by the old carbon effect, i.e., the assimilation of ancient dissolved inorganic carbon (DIC) derived from carbonate bedrocks or other sources. Therefore, radiocarbon dating is ideally performed on organic compounds derived from land plants that use atmospheric CO(2) and rapidly delivered to sediments. We demonstrate that lignin phenols isolated from lake sediments using reversed phase high performance liquid chromatography (HPLC) can serve as effective (14)C dating materials for establishing chronology during the late Quaternary. We developed a procedure to purify lignin phenols, building upon a published method. By isolating lignin from standard wood reference substances, we show that our method yields pure lignin phenols and consistent ages as the consensus ages and that our procedure does not introduce radiocarbon contamination. We further demonstrate that lignin phenol ages are compatible with varve counted and macrofossil dated sediment horizons in Steel Lake and Fayetteville Green Lake. Applying the new method to lake sediment cores from Lake Qinghai demonstrates that lignin phenol ages in Lake Qinghai are consistently younger than bulk total organic carbon (TOC) ages which are contaminated by old carbon effect. We also show that the age offset between lignin and bulk organic carbon differs at different Lake Qinghai sedimentary horizons, suggesting a variable hard water effect at different times and that a uniform age correction throughout the core is inappropriate.

[Publications in the Croatian medical journals by doctoral candidates at University of Zagreb School of Medicine].

PubMed

Sember, Marijan; Petrak, Jelka

2014-01-01

By searching Medline/PubMed bibliographic database we collected data on publications of two groups of PhD candidates who earned their PhD degrees at University of Zagreb Medical School in 2000 and 2010. We identifed their publications in the Croatian medical journals and separately in the Croatian language. First group of PhD candidates (y 2000) published in the Croatian journals 34% of all published papers, with a share of 29% in the Croatian language. Another group (y 2010) published in the Croatian journals 44% of all published papers in which the number of papers published in the Croatian journals in English language grow significantly (5% vs. 31%). The number of papers published in the Croatian language decreased to 13%. Our results agreed with the global decreasing trend of the number of medical papers in non-English languages. The importance of mother-tongue in the medical education and health care may have influence on preserving scientific communication in non-English medical journals.

Forgery at the Snite Museum of Art? Improving AMS Radiocarbon Dating at the University of Notre Dame

NASA Astrophysics Data System (ADS)

Troyer, Laura; Bagwell, Connor; Anderson, Tyler; Clark, Adam; Nelson, Austin; Skulski, Michael; Collon, Philippe

2017-09-01

The Snite Museum of Art recently obtained several donations of artifacts. Five of the pieces lack sufficient background information to prove authenticity and require further analysis to positively determine the artwork's age. One method to determine the artwork's age is radiocarbon dating via Accelerator Mass Spectrometry (AMS) performed at the University of Notre Dame's Nuclear Science Laboratory. Samples are prepared by combustion of a small amount of material and subsequent reduction to carbon into an iron powder matrix (graphitization). The graphitization procedure affects the maximum measurement rate, and a poor graphitization can be detrimental to the AMS measurement of the sample. Previous graphitization procedures resulted in a particle current too low or inconsistent to optimize AMS measurements. Thus, there was a desire to design and refine the graphitization system. The finalized process yielded physically darker samples and increased sample currents by two orders of magnitude. Additionally, the first testing of the samples was successful, yet analysis of the dates proved inconclusive. AMS measurements will be performed again to obtain better sampling statistics in the hopes of narrowing the reported date ranges. NSF and JINA-CEE.

Radiocarbon in CO2 and Soil Organic Matter from Laboratory Incubations, Barrow, Alaska, 2014

DOE Data Explorer

Lydia Vaughn; Margaret Torn

2018-02-20

Dataset includes 14C measurements made from soil organic matter and CO2 from paired anaerobic and aerobic laboratory soil incubations of active layer soils collected in Barrow, Alaska in 2014. In addition to 14CO2, dataset includes CO2 production rates and carbon and nitrogen concentrations. Samples were collected from intensive study site 1 areas A, B, and C, and the site 0 and AB transects, from specified positions in high-centered, flat-centered, and low centered polygons.

Radiocarbon Dating of an Olive Tree Cross-Section: New Insights on Growth Patterns and Implications for Age Estimation of Olive Trees.

PubMed

Ehrlich, Yael; Regev, Lior; Kerem, Zohar; Boaretto, Elisabetta

2017-01-01

The age of living massive olive trees is often assumed to be between hundreds and even thousands of years. These estimations are usually based on the girth of the trunk and an extrapolation based on a theoretical annual growth rate. It is difficult to objectively verify these claims, as a monumental tree may not be cut down for analysis of its cross-section. In addition, the inner and oldest part of the trunk in olive trees usually rots, precluding the possibility of carting out radiocarbon analysis of material from the first years of life of the tree. In this work we present a cross-section of an olive tree, previously estimated to be hundreds of years old, which was cut down post-mortem in 2013. The cross-section was radiocarbon dated at numerous points following the natural growth pattern, which was made possible to observe by viewing the entire cross-section. Annual growth rate values were calculated and compared between different radii. The cross-section also revealed a nearly independent segment of growth, which would clearly offset any estimations based solely on girth calculations. Multiple piths were identified, indicating the beginning of branching within the trunk. Different radii were found to have comparable growth rates, resulting in similar estimates dating the piths to the 19th century. The estimated age of the piths represent a terminus ante quem for the age of the tree, as these are piths of separate branches. However, the tree is likely not many years older than the dated piths, and certainly not centuries older. The oldest radiocarbon-datable material in this cross-section was less than 200 years old, which is in agreement with most other radiocarbon dates of internal wood from living olive trees, rarely older than 300 years.

Southern Appalachian hillslope erosion rates measured by soil and detrital radiocarbon in hollows

USGS Publications Warehouse

Hales, T.C.; Scharer, K.M.; Wooten, R.M.

2012-01-01

Understanding the dynamics of sediment generation and transport on hillslopes provides important constraints on the rate of sediment output from orogenic systems. Hillslope sediment fluxes are recorded by organic material found in the deposits infilling unchanneled convergent topographic features called hollows. This study describes the first hollow infilling rates measured in the southern Appalachian Mountains. Infilling rates (and bedrock erosion rates) were calculated from the vertical distribution of radiocarbon ages at two sites in the Coweeta drainage basin, western North Carolina. At each site we dated paired charcoal and silt soil organic matter samples from five different horizons. Paired radiocarbon samples were used to bracket the age of the soil material in order to capture the range of complex soil forming processes and deposition within the hollows. These dates constrain hillslope erosion rates of between 0.051 and 0.111mmyr-1. These rates are up to 4 times higher than spatially-averaged rates for the Southern Appalachian Mountains making creep processes one of the most efficient erosional mechanisms in this mountain range. Our hillslope erosion rates are consistent with those of forested mountain ranges in the western United States, suggesting that the mechanisms (dominantly tree throw) driving creep erosion in both the western United States and the Southern Appalachian Mountains are equally effective. ?? 2011 Elsevier B.V.

Fire and Fish: Using Radiocarbon And Stratigraphy To Discern The Impact Of Wildfire On Fish Metapopulations

NASA Astrophysics Data System (ADS)

Schaffrath, K. R.; Finch, C.; Belmont, P.; Budy, P.

2015-12-01

Wildfires have profound and variable impacts on erosion, channel morphology, and aquatic habitat. Previous research has quantified post-fire geomorphic response on event and millennial timescales. While these studies have informed our understanding of post-fire geomorphic response during the Holocene, we have yet to fully understand the variability of post-wildfire geomorphic response and how it might change in response to changing climate. Response of aquatic biota is just as variable as post-wildfire response yet we know very little about effects on metapopulations and how management decisions affect aquatic populations. Barriers to movement are installed to isolate native fish populations and prescribed fire and thinning are used to try to reduce future wildfire severity and extent. In order to improve understanding of the implications of management decisions, we evaluated geomorphic response and synchronicity of wildfires over the Holocene relative to the impact to the metapopulation of Bonneville cutthroat trout from a recent wildfire. The Twitchell Canyon fire burned 45,000 acres near Beaver, UT in July 2010. Over 30% of the area burned at high severity, which included two major headwater streams that sustained a trout population. In summer 2011, monsoonal thunderstorms caused massive debris flows and sheetflow erosion that altered channel morphology and aquatic habitat in the burned area. A previously robust, non-native trout fishery was nearly extirpated as a result of the geomorphic response to the wildfire. We used radiocarbon dating of burned material to determine how often headwater streams burned synchronously over the Holocene. Radiocarbon dates are associated with field observations of stratigraphy in order to infer geomorphic response to historic wildfires. Thirty samples were collected from sediment layers in 10 alluvial fans distributed among three watersheds (two burned and one unburned in the 2010 fire). Preliminary results suggest that we

Searching for the Oldest Baobab of Madagascar: Radiocarbon Investigation of Large Adansonia rubrostipa Trees

PubMed Central

Patrut, Adrian; von Reden, Karl F.; Danthu, Pascal; Leong Pock-Tsy, Jean-Michel; Patrut, Roxana T.; Lowy, Daniel A.

2015-01-01

We extended our research on the architecture, growth and age of trees belonging to the genus Adansonia, by starting to investigate large individuals of the most widespread Malagasy species. Our research also intends to identify the oldest baobabs of Madagascar. Here we present results of the radiocarbon investigation of the two most representative Adansonia rubrostipa (fony baobab) specimens, which are located in south-western Madagascar, in the Tsimanampetsotse National Park. We found that the fony baobab called “Grandmother” consists of 3 perfectly fused stems of different ages. The radiocarbon date of the oldest sample was found to be 1136 ± 16 BP. We estimated that the oldest part of this tree, which is mainly hollow, has an age close to 1,600 yr. This value is comparable to the age of the oldest Adansonia digitata (African baobab) specimens. By its age, the Grandmother is a major candidate for the oldest baobab of Madagascar. The second investigated specimen, called the “polygamous baobab”, consists of 6 partially fused stems of different ages. According to dating results, this fony baobab is 1,000 yr old. This research is the first investigation of the structure and age of Malagasy baobabs. PMID:25806967

Tips and traps in the 14C bio-AMS preparation laboratory

NASA Astrophysics Data System (ADS)

Buchholz, Bruce A.; Freeman, Stewart P. H. T.; Haack, Kurt W.; Vogel, John S.

2000-10-01

Maintaining a contamination free sample preparation lab for biological 14C AMS requires the same or more diligence as a radiocarbon dating prep lab. Isotope ratios of materials routinely range over 4-8 orders of magnitude in a single experiment, dosing solutions contain thousands of DPM and gels used to separate proteins possess 14C ratios of 1 amol 14C/mg C. Radiocarbon contamination is a legacy of earlier tracer work in most biological laboratories, even if they were never hot labs. Removable surface contamination can be found and monitored using swipes. Contamination can be found on any surface routinely touched: door knobs, light switches, drawer handles, water faucets. In general, all surfaces routinely touched need to be covered with paper, foil or plastic that can be changed frequently. Shared air supplies can also present problems by distributing hot aerosols throughout a building. Aerosols can be monitored for 14C content using graphitized coal or fullerene soot mixed with metal powder as an absorber. The monitors can be set out in work spaces for 1-2 weeks and measured by AMS with regular samples. Frequent air changes help minimize aerosol contamination in many cases. Cross-contamination of samples can be minimized by using disposable plastic or glassware in the prep lab, isolating samples from the air when possible and using positive displacement pipettors.

Clinical and Laboratoy Characteristics of Parvovirus B19 Infection During 2013/2014 Outbreak in Zagreb, Croatia

PubMed Central

Ajdukovic, Mia; Pejic, Lucija; Papic, Neven; Vince, Adriana

2017-01-01

Abstract Background Human Parvovirus B19 (HPV-B19) occurs worldwide and causes mild, acute exanthematous disease that occurs in a form of cyclic local epidemics. The aim of this study was to analyze clinical features and complication rates of acute HPV-B19 infection in different age groups. Methods We retrospectively reviewed the charts of 718 consecutive patients clinicaly diagnosed with acute HPV-B19 infection who visited outpatient department at the University Hospital for Infectious Diseases in Zagreb, Croatia during 2013–2014 outbreak. In 212 patients (of 298 tested) diagnosis was confirmed by positive IgM antibodies and/or HPV-B19 DNA in peripheral blood. Results Outbreak started in June 2013 and had a peak in April 2014, with highest prevalence in schoolchildren. There were no difference in clinical presentation or laboratory findings between clinicaly and serologicaly diagnosed patients. Biphasic presentation, fever, myalgia, arthralgia, headache and peripheral edema were more frequent in adults, but „slapped cheeks” was found predominantly in children. Complications were more common in adults, most commonly hematological disordes (mild anemia, thrombocytopenia and leukopenia), vasculitis, hepatitis and aseptic meningitis. There were no deaths in our cohort. Children 
(n = 52) Adults 
(n = 160) P-value Age, years 8.8 ± 4.1 39 ± 10.7 Male sex 31 (59.6%) 26 (12.3%) 0.0001 Clinical presentation Biphasic presentation 8 (15.4%) 48 (30.0 %) 0.0460 Fever 26 (50.0%) 110 (68.7%) 0.0194 Rash 51 (98.1%) 127 (79.4%) 0.0008 Myalgia 5 (9.6%) 50 (31.2%) 0.0017 Arthralgia 9 (17.3%) 100 (62.5%) 0.0001 Headache 3 (5.8%) 34 (21.2%) 0.0107 “Slapped cheeks” 29 (55,8%) 24 (15.0%) 0.0001 Peripheral edema 6 (11.5%) 63 (39.4%) 0.0001 Anemia 4 (7.7%) 19 (11.8%) 0.6076 Leukopenia 1 (1.9%) 23 (14.5%) 0.0111 Thrombocytopenia 4 (7.7%) 35 (21.8%) 0.0231 Hepatitis 1 (1.9%) 11 (6.87%) 0.3011 Vasculitis 1 (1.9%) 2 (1.25%) 0.5721 Other 2 (3.8%) 3 (1.9%) 0.5982 Conclusion

Turnover of Grassland Roots in Mountain Ecosystems Revealed by Their Radiocarbon Signature: Role of Temperature and Management

PubMed Central

Leifeld, Jens; Meyer, Stefanie; Budge, Karen; Sebastia, Maria Teresa; Zimmermann, Michael; Fuhrer, Juerg

2015-01-01

Root turnover is an important carbon flux component in grassland ecosystems because it replenishes substantial parts of carbon lost from soil via heterotrophic respiration and leaching. Among the various methods to estimate root turnover, the root’s radiocarbon signature has rarely been applied to grassland soils previously, although the value of this approach is known from studies in forest soils. In this paper, we utilize the root’s radiocarbon signatures, at 25 plots, in mountain grasslands of the montane to alpine zone of Europe. We place the results in context of a global data base on root turnover and discuss driving factors. Root turnover rates were similar to those of a subsample of the global data, comprising a similar temperature range, but measured with different approaches, indicating that the radiocarbon method gives reliable, plausible and comparable results. Root turnover rates (0.06–1.0 y-1) scaled significantly and exponentially with mean annual temperatures. Root turnover rates indicated no trend with soil depth. The temperature sensitivity was significantly higher in mountain grassland, compared to the global data set, suggesting additional factors influencing root turnover. Information on management intensity from the 25 plots reveals that root turnover may be accelerated under intensive and moderate management compared to low intensity or semi-natural conditions. Because management intensity, in the studied ecosystems, co-varied with temperature, estimates on root turnover, based on mean annual temperature alone, may be biased. A greater recognition of management as a driver for root dynamics is warranted when effects of climatic change on belowground carbon dynamics are studied in mountain grasslands. PMID:25734640

Source apportionment of elevated wintertime PAHs by compound-specific radiocarbon analysis

NASA Astrophysics Data System (ADS)

Sheesley, R. J.; Kruså, M.; Krecl, P.; Johansson, C.; Gustafsson, Ã.-.

2008-12-01

Natural abundance radiocarbon analysis facilitates distinct source apportionment between contemporary biomass/biofuel (14C "alive") versus fossil fuel (14C "dead") combustion. Here, the first compound-specific radiocarbon analysis (CSRA) of atmospheric polycylic aromatic hydrocarbons (PAHs) was demonstrated for a set of samples collected in Lycksele, Sweden a small town with frequent episodes of severe atmospheric pollution in the winter. Renewed interest in residential wood combustion means than this type of seasonal pollution is of increasing concern in many areas. Five individual/paired PAH isolates from three pooled fortnight-long filter collections were analyzed by CSRA: phenanthrene, fluoranthene, pyrene, benzo[b+k]fluoranthene and indeno[cd]pyrene plus benzo[ghi]perylene; phenanthrene was the only compound also analyzed in the gas phase. The measured Δ14C for PAHs spanned from -138.3‰ to 58.0‰. A simple isotopic mass balance model was applied to estimate the fraction biomass (fbiomass) contribution that was constrained to a range of 71% for indeno[cd]pyrene+benzo[ghi]perylene to 87% for the gas phase phenanthrene and particulate fluoranthene, respectively. Indeno[cd]pyrene plus benzo[ghi]perylene, known to be enhanced in gasoline-powered motor vehicle exhaust compared to diesel exhaust, had the lowest contribution of biomass combustion of the measured PAHs by 9%. The total organic carbon (TOC, defined as carbon remaining after removal of inorganic carbon) fbiomass was estimated to be 77%, which falls within the range for PAHs. This CSRA data of atmospheric PAHs demonstrate the non-uniformity of biomass combustion contribution to different PAHs even in a location with limited local emission sources and illustrates that regulatory efforts would not evenly reduce all PAHs.

Bomb-curve radiocarbon measurement of recent biologic tissues and applications to wildlife forensics and stable isotope (paleo)ecology

NASA Astrophysics Data System (ADS)

Uno, Kevin T.; Quade, Jay; Fisher, Daniel C.; Wittemyer, George; Douglas-Hamilton, Iain; Andanje, Samuel; Omondi, Patrick; Litoroh, Moses; Cerling, Thure E.

2013-07-01

Above-ground thermonuclear weapons testing from 1952 through 1962 nearly doubled the concentration of radiocarbon (14C) in the atmosphere. As a result, organic material formed during or after this period may be radiocarbon-dated using the abrupt rise and steady fall of the atmospheric 14C concentration known as the bomb-curve. We test the accuracy of accelerator mass spectrometry radiocarbon dating of 29 herbivore and plant tissues collected on known dates between 1905 and 2008 in East Africa. Herbivore samples include teeth, tusks, soft tissue, hair, and horn. Tissues formed after 1955 are dated to within 0.3-1.3 y of formation, depending on the tissue type, whereas tissues older than ca. 1955 have high age uncertainties (>17 y) due to the Suess effect. 14C dating of tissues has applications to stable isotope (paleo)ecology and wildlife forensics. We use data from 41 additional samples to determine growth rates of tusks, molars, and hair, which improve interpretations of serial stable isotope data for (paleo)ecological studies. 14C dating can also be used to calculate the time interval represented in periodic histological structures in dental tissues (i.e., perikymata), which in turn may be used as chronometers in fossil teeth. Bomb-curve 14C dating of confiscated animal tissues (e.g., ivory statues) can be used to determine whether trade of the item is legal, because many Convention of International Trade of Endangered Species restrictions are based on the age of the tissue, and thus can serve as a powerful forensic tool to combat illegal trade in animal parts.

Bomb-curve radiocarbon measurement of recent biologic tissues and applications to wildlife forensics and stable isotope (paleo)ecology.

PubMed

Uno, Kevin T; Quade, Jay; Fisher, Daniel C; Wittemyer, George; Douglas-Hamilton, Iain; Andanje, Samuel; Omondi, Patrick; Litoroh, Moses; Cerling, Thure E

2013-07-16

Above-ground thermonuclear weapons testing from 1952 through 1962 nearly doubled the concentration of radiocarbon ((14)C) in the atmosphere. As a result, organic material formed during or after this period may be radiocarbon-dated using the abrupt rise and steady fall of the atmospheric (14)C concentration known as the bomb-curve. We test the accuracy of accelerator mass spectrometry radiocarbon dating of 29 herbivore and plant tissues collected on known dates between 1905 and 2008 in East Africa. Herbivore samples include teeth, tusks, soft tissue, hair, and horn. Tissues formed after 1955 are dated to within 0.3-1.3 y of formation, depending on the tissue type, whereas tissues older than ca. 1955 have high age uncertainties (>17 y) due to the Suess effect. (14)C dating of tissues has applications to stable isotope (paleo)ecology and wildlife forensics. We use data from 41 additional samples to determine growth rates of tusks, molars, and hair, which improve interpretations of serial stable isotope data for (paleo)ecological studies. (14)C dating can also be used to calculate the time interval represented in periodic histological structures in dental tissues (i.e., perikymata), which in turn may be used as chronometers in fossil teeth. Bomb-curve (14)C dating of confiscated animal tissues (e.g., ivory statues) can be used to determine whether trade of the item is legal, because many Convention of International Trade of Endangered Species restrictions are based on the age of the tissue, and thus can serve as a powerful forensic tool to combat illegal trade in animal parts.

Radiocarbon of Respired CO2 Following Fire in Alaskan Boreal Forest: Can Disturbance Release Old Soil Carbon to the Atmosphere?

NASA Astrophysics Data System (ADS)

Schuur, E. A.; Randerson, J. A.; Fessenden, J.; Trumbore, S. E.

2002-12-01

Fire in the boreal forest releases carbon stored in vegetation and soil to the atmosphere. Following fire, microbial decomposition is stimulated by inputs of plant detritus and changes in soil microclimate, which can result in large losses of carbon. Furthermore, warmer summer soil temperatures and deeper thaw depths in burned ecosystems may make carbon that was previously climatically protected by low soil temperatures susceptible to decomposition. We used radiocarbon measurements to estimate the age of carbon released by soil respiration following fire in two black spruce (Picea mariana) forests in interior Alaska that burned during the summer of 1999. To isolate soil respiration, we established manipulated plots where vegetation was prevented from recolonizing, and paired control plots in nearby unburned forest. Soil respiration radiocarbon signatures in the burned manipulation ranged from +112\\permil to +192\\permil and differed significantly from the unburned controls that ranged from +100\\permil to +130\\permil. Burned plots appear to respire older carbon than unburned forest, which could either be due to the stimulation of decomposition of intermediate age soil organic matter pools, to the lack of plant respiration that reflects the atmospheric radiocarbon signature of +92\\permil, or both. At least during the initial phase following fire, these data suggest that carbon fluxes from soil are dominated by soil organic matter pools with decadal scale turnover times.

The impact of Last Glacial climate variability in west-European loess revealed by radiocarbon dating of fossil earthworm granules.

PubMed

Moine, Olivier; Antoine, Pierre; Hatté, Christine; Landais, Amaëlle; Mathieu, Jérôme; Prud'homme, Charlotte; Rousseau, Denis-Didier

2017-06-13

The characterization of Last Glacial millennial-timescale warming phases, known as interstadials or Dansgaard-Oeschger events, requires precise chronologies for the study of paleoclimate records. On the European continent, such chronologies are only available for several Last Glacial pollen and rare speleothem archives principally located in the Mediterranean domain. Farther north, in continental lowlands, numerous high-resolution records of loess and paleosols sequences show a consistent environmental response to stadial-interstadial cycles. However, the limited precision and accuracy of luminescence dating methods commonly used in loess deposits preclude exact correlations of paleosol horizons with Greenland interstadials. To overcome this problem, a radiocarbon dating protocol has been developed to date earthworm calcite granules from the reference loess sequence of Nussloch (Germany). Its application yields a consistent radiocarbon chronology of all soil horizons formed between 47 and 20 ka and unambiguously shows the correlation of every Greenland interstadial identified in isotope records with specific soil horizons. Furthermore, eight additional minor soil horizons dated between 27.5 and 21 ka only correlate with minor decreases in Greenland dust records. This dating strategy reveals the high sensitivity of loess paleoenvironments to Northern Hemisphere climate changes. A connection between loess sedimentation rate, Fennoscandian ice sheet dynamics, and sea level changes is proposed. The chronological improvements enabled by the radiocarbon "earthworm clock" thus strongly enhance our understanding of loess records to a better perception of the impact of Last Glacial climate changes on European paleoenvironments.

Radiocarbon dating the appearance of modern humans and timing of cultural innovations in Europe: new results and new challenges.

PubMed

Conard, Nicholas J; Bolus, Michael

2003-03-01

New radiocarbon dates from the sites of Bockstein-Törle, Geissenklösterle, Hohle Fels, Hohlenstein-Stadel, Sirgenstein, and Vogelherd in the Swabian Jura of southwestern Germany indicate that the Aurignacian of the region spans the period from ca. 40-30ka BP. If the situation at Vogelherd, in which skeletal remains from modern humans underlie an entire Aurignacian sequence, is viewed as representative for the region, the dates from the Swabian Jura support the hypothesis that populations of modern humans entered the region by way of the "Danube Corridor." The lithic technology from the lower Aurignacian of Geissenklösterle III is fully developed, and classic Aurignacian forms are well represented. During the course of the Aurignacian, numerous assemblages rich in art works, jewelry, and musical instruments are documented. By no later than 29ka BP the Gravettian was well established in the region. These dates are consistent with the "Kulturpumpe" hypothesis that important cultural innovations of the Aurignacian and Gravettian in Swabia predate similar developments in other regions of Europe. The radiocarbon dates from Geissenklösterle corroborate observations from other non-archaeological data sets indicating large global fluctuations in the atmospheric concentrations of radiocarbon between 30 and 50ka calendar years ago. These fluctuations lead to complications in building reliable chronologies during this period and cause the "Middle Paleolithic Dating Anomaly" and the "Coexistence Effect," which tend to exaggerate the temporal overlap between Neanderthals and modern humans.

The impact of Last Glacial climate variability in west-European loess revealed by radiocarbon dating of fossil earthworm granules

PubMed Central

Moine, Olivier; Antoine, Pierre; Hatté, Christine; Landais, Amaëlle; Mathieu, Jérôme; Prud’homme, Charlotte

2017-01-01

The characterization of Last Glacial millennial-timescale warming phases, known as interstadials or Dansgaard–Oeschger events, requires precise chronologies for the study of paleoclimate records. On the European continent, such chronologies are only available for several Last Glacial pollen and rare speleothem archives principally located in the Mediterranean domain. Farther north, in continental lowlands, numerous high-resolution records of loess and paleosols sequences show a consistent environmental response to stadial–interstadial cycles. However, the limited precision and accuracy of luminescence dating methods commonly used in loess deposits preclude exact correlations of paleosol horizons with Greenland interstadials. To overcome this problem, a radiocarbon dating protocol has been developed to date earthworm calcite granules from the reference loess sequence of Nussloch (Germany). Its application yields a consistent radiocarbon chronology of all soil horizons formed between 47 and 20 ka and unambiguously shows the correlation of every Greenland interstadial identified in isotope records with specific soil horizons. Furthermore, eight additional minor soil horizons dated between 27.5 and 21 ka only correlate with minor decreases in Greenland dust records. This dating strategy reveals the high sensitivity of loess paleoenvironments to Northern Hemisphere climate changes. A connection between loess sedimentation rate, Fennoscandian ice sheet dynamics, and sea level changes is proposed. The chronological improvements enabled by the radiocarbon “earthworm clock” thus strongly enhance our understanding of loess records to a better perception of the impact of Last Glacial climate changes on European paleoenvironments. PMID:28559353

Changes in groundwater reserves and radiocarbon and chloride content due to a wet period intercalated in an arid climate sequence in a large unconfined aquifer

NASA Astrophysics Data System (ADS)

Custodio, E.; Jódar, J.; Herrera, C.; Custodio-Ayala, J.; Medina, A.

2018-01-01

The concentration of atmospheric tracers in groundwater samples collected from springs and deep wells is, in most cases, the result of a mixture of waters with a wide range of residence times in the ground. Such is the case of an unconfined aquifer recharged over all its surface area. Concentrations greatly differ from the homogeneous residence time case. Data interpretation relies on knowledge of the groundwater flow pattern. To study relatively large systems, the conservative ion chloride and the decaying radiocarbon (14C) are considered. Radiocarbon (14C) activity in groundwater, after correction to discount the non-biogenic contribution, is often taken as an indication of water age, while chloride can be used to quantify recharge. In both cases, the observed tracer content in groundwater is an average value over a wide range which is related to water renewal time in the ground. This is shown considering an unconfined aquifer recharged all over its area under arid conditions, in which a period of greater recharge happened some millennia ago. The mathematical solution is given. As the solution cannot be made general, to show and discuss the changes in water reserve and in chloride and radiocarbon concentration (apparent ages), two scenarios are worked out, which are loosely related to current conditions in Northern Chile. It is shown that tracer concentration and the estimated water age are not directly related to the time since recharge took place. The existence of a previous wetter-than-present period has an important and lasting effect on current aquifer water reserves and chloride concentration, although the effect on radiocarbon activity is less pronounced. Chloride concentrations are smaller than in current recharge and apparent 14C ages do not coincide with the timing, duration and characteristics of the wet period, except in the case in which recharge before and after the wet period is negligible and dead aquifer reserves are non-significant. The use of

Assessment of the trace element distribution in soils in the parks of the city of Zagreb (Croatia).

PubMed

Roje, Vibor; Orešković, Marko; Rončević, Juraj; Bakšić, Darko; Pernar, Nikola; Perković, Ivan

2018-02-07

This paper presents the results of the preliminary testing of the selected trace elements in the soils of several parks in the city of Zagreb, Republic of Croatia. In each park, the samples were taken from several points-at various distances from the roads. The samples were taken at two different depths: 0-5 and 30-45 cm. Composite samples were done for each sampling point. Microwave-assisted wet digestion of the soil samples was performed and the determination by ICP-AES technique was done. Results obtained for Al, As, Ba, Mn, Ti, V, and K are in a good agreement with the results published in the scientific literature so far. The mass fraction values of Cd, Cr, Cu, Ni, Pb, and Zn are somewhat higher than the maximum values given in the Croatian Directive on agricultural land protection against pollution. Be, Mo, Sb, Se, and Tl in the samples were present in the concentrations that are lower than their method detection limit values.

Medical Students’ Clinical Skills Do Not Match Their Teachers’ Expectations: Survey at Zagreb University School of Medicine, Croatia

PubMed Central

Sičaja, Mario; Romić, Dominik; Prka, Željko

2006-01-01

Aim To evaluate self-assessed level of clinical skills of graduating medical students at Zagreb University School of Medicine and compare them with clinical skill levels expected by their teachers and those defined by a criterion standard. Method The study included all medical students (n = 252) graduating from the Zagreb University School of Medicine in the 2004-2005 academic year and faculty members (n = 129) teaching clinical skills. The participants completed anonymous questionnaire listing 99 clinical skills divided into nine groups. Students were asked to assess their clinical skills on a 0-5 scale, and faculty members were asked to assess the minimum necessary level of clinical skills expected from graduating medical students, using the same 0-5 scale. We compared the assessment scores of faculty members with students’ self-assessment scores. Participants were grouped according to their descriptive characteristics for further comparison. Results The response rate was 91% for students and 70% for faculty members. Students’ self-assessment scores in all nine groups of clinical skills ranged from 2.2 ± 0.8 to 3.8 ± 0.5 and were lower than those defined by the criterion standard (3.0-4.0) and those expected by teachers (from 3.1 ± 1.0 to 4.4 ± 0.5) (P<0.001 for all). Students who had additional clinical skills training had higher scores in all groups of skills, ranging from 2.6 ± 0.9 to 4.0 ± 0.5 (P<0.001 for all). Male students had higher scores than female students in emergency (P<0.001), neurology (P = 0.017), ear, nose, and throat (P = 0.002), urology (P = 0.003), and surgery skills (P = 0.002). Teachers’ expectations did not vary according to their sex, academic position, or specialty. Conclusion Students’ self-assessed level of clinical skills was lower than that expected by their teachers. Education during clinical rotations is not focused on acquiring clinical skills, and additional clinical

Indian Ocean radiocarbon: Data from the INDIGO 1, 2, and 3 cruises

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sepanski, R.J.

1991-01-01

This document presents {sup 14}C activities (expressed in the internationally adopted {Delta}{sup 14}C scale) from water samples taken at various locations and depths in the Indian and Southern oceans through the Indien Gaz Ocean (INDIGO) project. These data were collected as part of the INDIGO 1, INDIGO 2, and INDIGO 3 cruises, which took place during the years 1985, 1986, and 1987, respectively. These data have been used to estimate the penetration of anthropogenic CO{sub 2} in the Indian and Southern oceans. The document also presents supporting data for potential temperature, salinity, density (sigma-theta), {delta}{sup 13}C, and total CO{sub 2}.more » All radiocarbon measurements have been examined statistically for quality of sample counts and stability of counting efficiency and background. In addition, all data have been reviewed by the Carbon Dioxide Information Analysis Center and assessed for gross accuracy and consistency (absence of obvious outliers and other anomalous values). These data are available free of charge as a numeric data package (NDP) from the Carbon Dioxide Information Analysis Center. The NDP consists of this document and a magnetic tape containing machine-readable files. This document provides sample listing of the Indian Ocean radiocarbon data as they appear on the magnetic tape, as well as a complete listing of these data in tabular form. This document also offers retrieval program listings, furnishes information on sampling methods and data selection, defines limitations and restrictions of the data, and provides reprints of pertinent literature. 13 refs., 4 tabs.« less

Antibiotic susceptibility of isolates from paediatric intensive care units in Zagreb.

PubMed

Bedenić, Branka; Prahin, Esmina; Vranić-Ladavac, Mirna; Atalić, Vlasta; Sviben, Mario; Frančula-Zaninović, Sonja; Plečko, Vanda; Kalenić, Smilja

2014-02-01

Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program is a longitudinal global surveillance study to monitor in vitro data on microbial susceptibility in centers that prescribe meropenem. Results of the six years period (2002-2007) for the antimicrobial efficacy of meropenem compared to other broad-spectrum agents against Gram-negative and Gram-positive isolates collected at pediatric intensive care units of the University Hospital Center Zagreb in Croatia were reported. A total of 110 Gram-negative and 43 Gram-positive pathogens from pediatric specimens were tested. The minimum-inhibitory concentrations (MICs) were determined by broth microdilution method according to CLSI. There was no resistance to either imipenem or meropenem observed for Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis. High resistance rates of K. pneumoniae to ceftazidime and gentamicin (50%) are a raising concern. Pseudomonas aeruginosa was the most resistant Gram-negative species with two (12%) of the strains resistant to meropenem, three (18%) to imipenem, 10 (47%) to gentamicin and six (35%) to piperacillin/tazobactam and ciprofloxacin. According to our results meropenem remains an appropriate antibiotic for the treatment of severe infections caused by Gram-negative bacteria in pediatric population. The results indicate that meropenem has excellent potency and spectrum of activity despite being prescribed for a long time for the treatment of seriously ill patients, and still appears to be a reliable option for the initial empirical therapy of serious nosocomial infections in children. However, later studies have shown the emergence of carbapenem-resistant Gram-negative bacteria after 2008.

Radiocarbon Evidence That Millennial and Fast-Cycling Soil Carbon are Equally Sensitive to Warming

NASA Astrophysics Data System (ADS)

Vaughn, L. S.; Torn, M. S.; Porras, R. C.

2017-12-01

Within the century, the Arctic is expected to shift from a sink to a source of atmospheric CO2 due to climate-induced increases in soil carbon mineralization. The magnitude of this effect remains uncertain, due in large part to unknown temperature sensitivities of organic matter decomposition. In particular, the distribution of temperature sensitivities across soil carbon pools remains unknown. New experimental approaches are needed, because studies that fit multi-pool models to CO2 flux measurements may be sensitive to model assumptions, statistical effects, and non-steady-state changes in substrate availability or microbial activity. In this study, we developed a new methodology using natural abundance radiocarbon to evaluate temperature sensitivities across soil carbon pools. In two incubation experiments with soils from Barrow, AK, we (1) evaluated soil carbon age and decomposability, (2) disentangled the effects of temperature and substrate depletion on carbon mineralization, and (3) compared the temperature sensitivities of fast- and slow-cycling soil carbon pools. From a long-term incubation, both respired CO2 and the remaining soil organic matter were highly depleted in radiocarbon. At 20 cm depth, median Δ14C values were -167‰ in respired CO2 and -377‰ in soil organic matter, corresponding to turnover times of 1800 and 4800 years, respectively. Such negative Δ14C values indicate both storage and decomposition of old, stabilized carbon, while radiocarbon differences between the mineralized and non-mineralized fractions suggest that decomposability varies along a turnover time gradient. Applying a new analytical method combining CO2 flux and Δ14C, we found that fast- and slow-cycling carbon pools were equally sensitive to temperature, with a Q10 of 2 irrespective of turnover time. We conclude that in these Arctic soils, ancient soil carbon is vulnerable to warming under thawed, aerobic conditions. In contrast to many previous studies, we found no

Late Quaternary sedimentological and climate changes at Lake Bosumtwi Ghana: new constraints from laminae analysis and radiocarbon age modeling

USGS Publications Warehouse

Shanahan, Timothy M.; Beck, J. Warren; Overpeck, Jonathan T.; McKay, Nicholas P.; Pigati, Jeffrey S.; Peck, John A.; Scholz, Christopher A.; Heil, Clifford W.; King, John W.

2012-01-01

The Lake Bosumtwi sediment record represents one of the longest and highest-resolution terrestrial records of paleoclimate change available from sub-Saharan Africa. Here we report a new sediment age model framework for the last ~ 45 cal kyr of sedimentation using a combination of high-resolution radiocarbon dating, Bayesian age-depth modeling and lamination counting. Our results highlight the practical limits of these methods for reducing age model uncertainties and suggest that even with very high sampling densities, radiocarbon uncertainties of at least a few hundred years are unavoidable. Age model uncertainties are smallest during the Holocene (205 yr) and the glacial (360 yr) but are large at the base of the record (1660 yr), due to a combination of decreasing sample density, larger calibration uncertainties and increases in radiocarbon age scatter. For portions of the chronology older than ~ 35 cal kyr, additional considerations, such as the use of a low-blank graphitization system and more rigorous sample pretreatment were necessary to generate a reliable age depth model because of the incorporation of small amounts of younger carbon. A comparison of radiocarbon age model results and lamination counts over the time interval ~ 15–30 cal kyr agree with an overall discrepancy of ~ 10% and display similar changes in sedimentation rate, supporting the annual nature of sediment laminations in the early part of the record. Changes in sedimentation rates reconstructed from the age-depth model indicate that intervals of enhanced sediment delivery occurred at 16–19, 24 and 29–31 cal kyr, broadly synchronous with reconstructed drought episodes elsewhere in northern West Africa and potentially, with changes in Atlantic meridional heat transport during North Atlantic Heinrich events. These data suggest that millennial-scale drought events in the West African monsoon region were latitudinally extensive, reaching within several hundred kilometers of the Guinea coast

Associated terrestrial and marine fossils in the late-glacial Presumpscot Formation, southern Maine, USA, and the marine reservoir effect on radiocarbon ages

USGS Publications Warehouse

Thompson, W.B.; Griggs, C.B.; Miller, N.G.; Nelson, R.E.; Weddle, T.K.; Kilian, T.M.

2011-01-01

Excavations in the late-glacial Presumpscot Formation at Portland, Maine, uncovered tree remains and other terrestrial organics associated with marine invertebrate shells in a landslide deposit. Buds of Populus balsamifera (balsam poplar) occurred with twigs of Picea glauca (white spruce) in the Presumpscot clay. Tree rings in Picea logs indicate that the trees all died during winter dormancy in the same year. Ring widths show patterns of variation indicating responses to environmental changes. Fossil mosses and insects represent a variety of species and wet to dry microsites. The late-glacial environment at the site was similar to that of today's Maine coast. Radiocarbon ages of 14 tree samples are 11,907??31 to 11,650??5014C yr BP. Wiggle matching of dated tree-ring segments to radiocarbon calibration data sets dates the landslide occurrence at ca. 13,520+95/??20calyr BP. Ages of shells juxtaposed with the logs are 12,850??6514C yr BP (Mytilus edulis) and 12,800??5514C yr BP (Balanus sp.), indicating a marine reservoir age of about 1000yr. Using this value to correct previously published radiocarbon ages reduces the discrepancy between the Maine deglaciation chronology and the varve-based chronology elsewhere in New England. ?? 2011 University of Washington.

Associated terrestrial and marine fossils in the late-glacial Presumpscot Formation, southern Maine, USA, and the marine reservoir effect on radiocarbon ages

NASA Astrophysics Data System (ADS)

Thompson, Woodrow B.; Griggs, Carol B.; Miller, Norton G.; Nelson, Robert E.; Weddle, Thomas K.; Kilian, Taylor M.

2011-05-01

Excavations in the late-glacial Presumpscot Formation at Portland, Maine, uncovered tree remains and other terrestrial organics associated with marine invertebrate shells in a landslide deposit. Buds of Populus balsamifera (balsam poplar) occurred with twigs of Picea glauca (white spruce) in the Presumpscot clay. Tree rings in Picea logs indicate that the trees all died during winter dormancy in the same year. Ring widths show patterns of variation indicating responses to environmental changes. Fossil mosses and insects represent a variety of species and wet to dry microsites. The late-glacial environment at the site was similar to that of today's Maine coast. Radiocarbon ages of 14 tree samples are 11,907 ± 31 to 11,650 ± 50 14C yr BP. Wiggle matching of dated tree-ring segments to radiocarbon calibration data sets dates the landslide occurrence at ca. 13,520 + 95/-20 cal yr BP. Ages of shells juxtaposed with the logs are 12,850 ± 65 14C yr BP ( Mytilus edulis) and 12,800 ± 55 14C yr BP ( Balanus sp.), indicating a marine reservoir age of about 1000 yr. Using this value to correct previously published radiocarbon ages reduces the discrepancy between the Maine deglaciation chronology and the varve-based chronology elsewhere in New England.

Mauna Loa eruptive history—The preliminary radiocarbon record

NASA Astrophysics Data System (ADS)

Lockwood, John P.

Radiocarbon dating of charcoal from beneath lava flows of Mauna Loa has provided the most detailed prehistoric eruptive chronology of any volcano on Earth. Three hundred and fifty-five 14C dates have been reviewed, stratigraphically contradictory dates have been rejected, and multiple dates on single flows averaged to give "reliable" ages on 170 separate lava flows (about 35% of the total number of prehistoric Mauna Loa flows mapped to date). The distribution of these ages has revealed fundamental variations in the time and place of Mauna Loa eruptive activity, particularly for Holocene time. As lava flow activity from Mauna Loa's summit waxes, activity on the rift zones wanes. A cyclic model is proposed which involves a period of concentrated summit shield-building activity associated with long-lived lava lakes and frequent overflows of pahoehoe lavas on the north and southeast flanks. At this time, compressive stresses across Mauna Loa's rift zones are relatively high, inhibiting eruptions in these areas. This period is then followed by a relaxation of stresses across Mauna Loa's rift zones and a long period of frequent rift zone eruptions as magma migrates downrift. This change of eruptive style is marked by summit caldera collapse (possibly associated with massive eruptions of picritic lavas low on the rift zones). Concurrent with this increased rift zone activity, the summit caldera is gradually filled by repeated summit eruptions, stress across the rift zones increases, magma rises more easily to the summit, rift activity wanes, and the cycle repeats itself. Two such cycles are suggested within the late Holocene, each lasting 1,500-2,000 years. Earlier evidence for such cycles is obscure. Mauna Loa appears to have been quiescent between 6-7 ka, for unknown reasons. A period of increased eruptive activity marked the period 8-11 ka, coincident with the Pleistocene-Holocene boundary. Other volcanoes on the Island of Hawaii for which (limited) radiocarbon dating

Fine structure of the absorbed dose rate monitored in Zagreb, Croatia, in the period 1985-2011.

PubMed

Babić, D; Senčar, J; Petrinec, B; Marović, G; Bituh, T; Skoko, B

2013-04-01

We report on the fine structure of the absorbed dose rate D which was measured and recorded on a daily basis at the Institute for Medical Research and Occupational Health in Zagreb, Croatia, throughout the period 1985-2011. After the Chernobyl accident, D increased steeply by a factor of 3.5, but this is the only prominent feature in the D versus time (t) curve. In the absence of accidental conditions, the D(t) is flat and amounts to 30-35 pGy/s. Despite the apparent plainness of D(t), its Fourier transform reveals several periodic modulations hidden in the noise. Some of the corresponding periods (6 and 12 months) can be related to seasonal atmospheric changes but this is not the case with the other periods identified (9.3, 13.7, 15.7, 20, 31, and 39 months). These are found to agree well with literature data on periodicities in solar activity, which implies that they are most probably linked to variations in the atmospheric production of (7)Be by cosmic rays. Copyright © 2012 Elsevier Ltd. All rights reserved.

Curricular and extracurricular activities of medical students during war, Zagreb University School of Medicine, 1991-1995.

PubMed

Gluncić, V; Pulanić, D; Prka, M; Marusíc, A; Marusíc, M

2001-01-01

War, as a major human disaster, affects many aspects of life, including medical education. This report describes curricular and extracurricular activities of the students at the Zagreb University School of Medicine during the wars in Croatia and neighboring Bosnia and Herzegovina. Although condensed versions of the curricula were prepared in case of a major breakdown in civilian life, the school maintained the continuity and quality of its curriculum throughout the war. Students engaged in extracurricular activities related to medical aspects of the war, including organization of resuscitation and first aid courses, collecting medical documentation on war victims, humanitarian help to refugees, and peace-promoting activities. Some students joined mobile surgical teams on the battlefronts. After army service, most of them returned to the school and successfully continued with their studies. The school also accepted guest-students from other new states emerged from former Yugoslavia. The authors found that the students' engagement in extracurricular activities related to medicine was enormously beneficial both to the psychological well-being of the students and to the region's peace-building efforts.

Bomb-curve radiocarbon measurement of recent biologic tissues and applications to wildlife forensics and stable isotope (paleo)ecology

PubMed Central

Uno, Kevin T.; Quade, Jay; Fisher, Daniel C.; Wittemyer, George; Douglas-Hamilton, Iain; Andanje, Samuel; Omondi, Patrick; Litoroh, Moses; Cerling, Thure E.

2013-01-01

Above-ground thermonuclear weapons testing from 1952 through 1962 nearly doubled the concentration of radiocarbon (14C) in the atmosphere. As a result, organic material formed during or after this period may be radiocarbon-dated using the abrupt rise and steady fall of the atmospheric 14C concentration known as the bomb-curve. We test the accuracy of accelerator mass spectrometry radiocarbon dating of 29 herbivore and plant tissues collected on known dates between 1905 and 2008 in East Africa. Herbivore samples include teeth, tusks, soft tissue, hair, and horn. Tissues formed after 1955 are dated to within 0.3–1.3 y of formation, depending on the tissue type, whereas tissues older than ca. 1955 have high age uncertainties (>17 y) due to the Suess effect. 14C dating of tissues has applications to stable isotope (paleo)ecology and wildlife forensics. We use data from 41 additional samples to determine growth rates of tusks, molars, and hair, which improve interpretations of serial stable isotope data for (paleo)ecological studies. 14C dating can also be used to calculate the time interval represented in periodic histological structures in dental tissues (i.e., perikymata), which in turn may be used as chronometers in fossil teeth. Bomb-curve 14C dating of confiscated animal tissues (e.g., ivory statues) can be used to determine whether trade of the item is legal, because many Convention of International Trade of Endangered Species restrictions are based on the age of the tissue, and thus can serve as a powerful forensic tool to combat illegal trade in animal parts. PMID:23818577

Determination of 14C/ 12C of acetaldehyde in indoor air by compound specific radiocarbon analysis

NASA Astrophysics Data System (ADS)

Kato, Yoshimi; Shinohara, Naohide; Yoshinaga, Jun; Uchida, Masao; Matsuda, Ayuri; Yoneda, Minoru; Shibata, Yasuyuki

A method of compound-specific radiocarbon analysis (CSRA) for acetaldehyde in indoor air was established for the source apportionment purpose and the methodology was applied to indoor air samples. Acetaldehyde in indoor air samples was collected using the conventional 2,4-dinitrophenylhydrazine (DNPH) derivatization method. Typically 24-h air sampling at 5-10 L min -1 allowed collection of adequate amount of acetaldehyde for radiocarbon analysis by accelerator mass spectrometry (AMS). The 14C abundance of acetaldehyde in indoor air was measured by AMS after solvent extraction of derivatized acetaldehyde and sequential purification by a preparative liquid chromatography system and a preparative capillary gas chromatography system. The recovery and purity of the derivatized acetaldehyde was satisfactory for 14C analysis by AMS. 14C abundance of acetaldehyde was calculated by considering that of derivatizing agent DNPH. Our preliminary survey showed that percent modern carbon (pMC) values of acetaldehyde isolated from indoor air sampled in newly built, unoccupied housings ( n=5) in the suburb of Tokyo ranged from 49.4 to 67.0. This result indicated that contribution of anthropogenic source was greater than previously expected.

Radiocarbon dating of the Late Cycladic building and destruction phases at Akrotiri, Thera: New evidence

NASA Astrophysics Data System (ADS)

Maniatis, Yannis

2012-01-01

Akrotiri was a flourishing prehistoric settlement on the Cycladic island of Santorini (Thera) until its life was ended by a huge volcanic eruption in the LCI period. There is much debate as to when this final destruction occurred. Based on the Egyptian historical dating this happened around 1540-1530 BC, while, based on radiocarbon and other scientific data, around 1640-1600 BC. This work is an attempt to date with radiocarbon the whole settlement's life starting from the earlier phases of occupation but focusing in the sequence of the latest events. The samples, coming from the deep shafts dug in the site for the pillars of the new shelter, are pieces of wood and charcoal from house architectural elements and other constructions, including the final earthquake victims temporary camps. Therefore, the dates obtained represent the beginning of the different cultural phases plus the latest events. The results provide novel absolute dates for the commencement of the LMC and LCI Phases at Akrotiri, giving mean ranges around 1820-1790 BC and 1775-1722 BC, respectively, while the final destruction is dated around 1622-1548 BC. These results show that the LCI phase started about 100 years earlier than estimated with the Egyptian Historical chronology while the final destruction around 60 years or less earlier.

Age validation of quillback rockfish (Sebastes maliger) using bomb radiocarbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kerr, L A; Andrews, A H; Munk, K

2005-01-05

Rockfishes (Sebastes spp.) support one of the most economically important fisheries of the Pacific Northwest and it is essential for sustainable management that age estimation procedures be validated for these species. Atmospheric testing of thermonuclear devices during the 1950s and 1960s created a global radiocarbon ({sup 14}C) signal in the ocean environment that scientists have identified as a useful tracer and chronological marker in natural systems. In this study, we first demonstrated that fewer samples are necessary for age validation using the bomb-generated {sup 14}C signal by emphasizing the utility of the time-specific marker created by the initial rise ofmore » bomb-{sup 14}C. Second, the bomb-generated {sup 14}C signal retained in fish otoliths was used to validate the age and age estimation methodology of the quillback rockfish (Sebastes maliger) in the waters of southeast Alaska. Radiocarbon values from the first year's growth of quillback rockfish otoliths were plotted against estimated birth year producing a {sup 14}C time series spanning 1950 to 1985. The initial rise of bomb-{sup 14}C from pre-bomb levels ({approx} -90 {per_thousand}) occurred in 1959 {+-} 1 year and {sup 14}C levels rose relatively rapidly to peak {Delta}{sup 14}C values in 1967 (+105.4 {per_thousand}), with a subsequent declining trend through the end of the record in 1985 (+15.4 {per_thousand}). The agreement between the year of initial rise of {sup 14}C levels from the quillback rockfish record and the chronometer determined for the waters of southeast Alaska from yelloweye rockfish (S. ruberrimus) otoliths validated the ageing methodology for the quillback rockfish. The concordance of the entire quillback rockfish {sup 14}C record with the yelloweye rockfish time series demonstrated the effectiveness of this age validation technique, confirmed the longevity of the quillback rockfish up to a minimum of 43 years, and strongly supports higher age estimates of up to 90 years.« less

A case of early Wisconsinan ;over-chill;: New radiocarbon evidence for early extirpation of western camel (Camelops hesternus) in eastern Beringia

NASA Astrophysics Data System (ADS)

Zazula, Grant D.; MacPhee, Ross D. E.; Southon, John; Nalawade-Chavan, Shweta; Reyes, Alberto V.; Hewitson, Susan; Hall, Elizabeth

2017-09-01

There are comparatively few fossils that document the presence of the Pleistocene western camel (Camelops hesternus) in the unglaciated regions of Alaska and Yukon, northwestern North America (eastern Beringia). It has been previously reported on the basis of stratigraphic and radiocarbon data that this species was present within this region from the Sangamonian interglaciation (Marine Isotope Stage (MIS) 5) through the Last Glacial Maximum (LGM, MIS 2). However, the continued presence of western camel through the LGM is at odds with its ecological preferences as inferred from more southerly parts of the continent. Here we report 43 new radiocarbon dates on 34 western camel fossils from Alaska and Yukon, including specimens that have been dated previously. To minimize exogenous carbon contamination, we utilized either ultrafiltered collagen or single amino acid (hydroxyproline) methodologies in conducting the analyses. All samples, including previously reported specimens with finite ages, yielded ages that were either non-finite or close to the effective limit of radiocarbon dating. These results indicate that dates implying local presence of western camels in Alaska and Yukon during full-glacial conditions of MIS 2 are erroneous by as much as several tens of millennia, probably because of carbon contamination from glue or varnish used in fossil preparation and conservation. The revised radiocarbon chronology, together with other evidence, indicates that western camels were only able to occupy eastern Beringia only during Pleistocene interglaciations such as MIS 5, when forests and shrublands became the dominant regional biomes. The subsequent transition to cold, arid full-glacial conditions during the early Wisconsinan glaciation (MIS 4) around 75 000 years ago created unfavorable environmental conditions, eliminated browse, and led to their local extirpation in eastern Beringia. After their complete population loss in the Arctic and Subarctic, the range of

Prevalence of the metabolic syndrome in the old institutionalized people in Zagreb, Croatia.

PubMed

Nevajda, Branimir; Havelka-Mestrović, Ana; Bilić, Morana; Nevajda, Andreja Podvez; Romić, Dominik; Vuletić, Vladimira; Cukljek, Snjezana; Sicaja, Mario; Bocina, Zeljko

2013-03-01

Metabolic syndrome (MeS) is defined by a cluster of abnormalities comprising obesity, hypertension, carbohydrate intolerance and dyslipidemia. MeS increases the risk of developing various diseases, including coronary heart disease, stroke, peripheral angiopathy and type 2 diabetes. In our study, the subjects were 561 persons, residents of 11 homes for the elderly in Zagreb, Croatia. There were 160 men (28.5%) and 401 women (71.5%), aged from 56 to 96 years (the average being 79 years). Physical examination was conducted, which included blood pressure measurement, and body height and weight. Blood samples were taken for biochemical analysis. Along with other biochemical parameters, the levels of glucose, triglycerides and cholesterol (LDL, HDL-C) were also measured. The results have shown the prevalence of MeS in the elderly instutionalised people to be in the range of 20.8%, according to WHO criteria. The most common MeS component was hypertension, and it was significantly more frequent in women than in men; also, the elevated triglyceride levels were more often found in women; the difference between men and women was also statistically significant. MeS is a serious and growing health problem not only in Croatia but worldwide as well. Further studies are needed to verify the prevalence of MeS in Croatia, as it is a major risk for CVD and many other severe diseases.

Head-to-head immunogenicity comparison of Edmonston-Zagreb vs. AIK-C measles vaccine strains in infants aged 8-12 months: A randomized clinical trial.

PubMed

Izadi, Shahrokh; Zahraei, Seyed Mohsen; Salehi, Masoud; Mohammadi, Mahdi; Tabatabaei, Seyed Mehdi; Mokhtari-Azad, Talat

2018-01-29

A non-inferiority multi-centre parallel randomized double-blind trial was implemented in Zahedan district, Sistan-va-Baluchestan province, Iran, to compare the performance of the two measles vaccines which are in use in the National Immunization Programme of Iran and are of two different measles virus vaccine strains: Edmonston-Zagreb (EZ) strain vs. AIK-C strain. The main outcome measure was appearance of anti-measles antibody in sera. 200 infants, 8-12 months old, whose parents consented for their children to be included in the study, were randomized in permutation blocks of size 4-8 in four Urban Health Clinics. Having given a pre-vaccination blood sample, they received measles-rubella vaccine containing one of the vaccine strains mentioned before. After 60 days, the second blood sample was taken. The sera of the pre- and post-vaccination blood samples were tested for anti-measles antibodies in the National Reference Measles Laboratory. Parents, laboratory technicians and statistician were blind to groupings. Of the 200 children equally randomized in the two arms, 185 who were seronegative before vaccination (88 in the EZ arm and 97 in the AIK-C arm) were entered in the final analysis. The seroconversion rate in the EZ arm was 76.1% (95% CI: 60.2-85.2%), and that in the AIK-C arm was 58.7%; (95% CI: 48.8-68.7%). The absolute rate difference was 17. 4% (4.1-30.9%; P-value: .012), and the relative seroconversion rate of EZ to AIK-C was 1.3 (95% CI: 1.1-1.6; P-value: .012). No adverse events were reported during the study period. A considerable difference in the seropositivity of different measles containing vaccines could be demonstrated in the first year of life. Iranian Registry of Clinical Trials Registration Number: IRCT2016032827144N1; May 10, 2016 (www.who.int/ictrp/network/irct/en/). Copyright © 2017 Elsevier Ltd. All rights reserved.

[Resistance of uropathogenic strains of Escherichia coli in pregnant women and other women in generative ages in comparison with antibiotics consumption in Zagreb].

PubMed

Culig, Josip; Mlinarić-Dzepina, Ana; Leppée, Marcel; Vranes, Jasmina

2010-02-01

To compare resistance of uropathogenic strains of Escherichia coli (UPEC) to antibiotics in women in generative ages and pregnant women during two year period (2004 and 2008) in Zagreb, and comparison of resistance and the consumption of antibiotics. The standard disk-diffusion method was used for sensitivity testing to 16 different antibiotics. Data on antibiotic utilization were used to calculate the number of defined daily doses (DDD) and DDD per 1000 inhabitants using Anatomical-Therapeutic-Chemical/DDD methodology. Data on antibiotic consumption during pregnancy were collected using a questionnaire filled in by 893 women after delivery. During 2004 resistance of UPEC to antimicrobial drugs was not different in pregnant and in non-pregnant women, with the exception of amoxicillin and nitrofurantoin, with statistically higher resistance in pregnant women (p < 0.01). Four years later the statistically higher resistance to norfloxacin was observed in non-pregnant women (p < 0.01). Comparing the resistance in 2004 and 2008, in the both groups of women a statistically significant decrease of resistance to cefalexin and nitrofurantoin was detected (p < 0.01). Outpatient utilization of antimicrobial drugs in Zagreb increased significantly, from 32 to 39 DDD/1000 inhabitants per day. The most used antibiotic was co-amoxiclav, and its utilization increased from 9.6 to 12.2 DDD/1000/day. Amoxicillin and co-amoxiclav were used during pregnancy by 9.6% interviewed women. The observed significant decrease of resistance to cefalexin makes that antibiotic the drug of choice for treatment of urinary tract infections in women in generative ages, and together with coamoxiclav can be administered in pregnancy. Constant monitoring of urinary tract pathogens resistance to antimicrobial agents ensures the effectiveness of empirical therapy, whose versatile use is limited due the potentially harmful effects of antimicrobial drugs on fetus.

Radiocarbon chronology of Manot Cave, Israel and Upper Paleolithic dispersals

PubMed Central

Alex, Bridget; Barzilai, Omry; Hershkovitz, Israel; Marder, Ofer; Berna, Francesco; Caracuta, Valentina; Abulafia, Talia; Davis, Lauren; Goder-Goldberger, Mae; Lavi, Ron; Mintz, Eugenia; Regev, Lior; Bar-Yosef Mayer, Daniella; Tejero, José-Miguel; Yeshurun, Reuven; Ayalon, Avner; Bar-Matthews, Mira; Yasur, Gal; Frumkin, Amos; Latimer, Bruce; Hans, Mark G.; Boaretto, Elisabetta

2017-01-01

The timing of archeological industries in the Levant is central for understanding the spread of modern humans with Upper Paleolithic traditions. We report a high-resolution radiocarbon chronology for Early Upper Paleolithic industries (Early Ahmarian and Levantine Aurignacian) from the newly excavated site of Manot Cave, Israel. The dates confirm that the Early Ahmarian industry was present by 46,000 calibrated years before the present (cal BP), and the Levantine Aurignacian occurred at least between 38,000 and 34,000 cal BP. This timing is consistent with proposed migrations or technological diffusions between the Near East and Europe. Specifically, the Ahmarian could have led to the development of the Protoaurignacian in Europe, and the Aurignacian in Europe could have spread back to the Near East as the Levantine Aurignacian. PMID:29152566

Radiocarbon chronology of Manot Cave, Israel and Upper Paleolithic dispersals.

PubMed

Alex, Bridget; Barzilai, Omry; Hershkovitz, Israel; Marder, Ofer; Berna, Francesco; Caracuta, Valentina; Abulafia, Talia; Davis, Lauren; Goder-Goldberger, Mae; Lavi, Ron; Mintz, Eugenia; Regev, Lior; Bar-Yosef Mayer, Daniella; Tejero, José-Miguel; Yeshurun, Reuven; Ayalon, Avner; Bar-Matthews, Mira; Yasur, Gal; Frumkin, Amos; Latimer, Bruce; Hans, Mark G; Boaretto, Elisabetta

2017-11-01

The timing of archeological industries in the Levant is central for understanding the spread of modern humans with Upper Paleolithic traditions. We report a high-resolution radiocarbon chronology for Early Upper Paleolithic industries (Early Ahmarian and Levantine Aurignacian) from the newly excavated site of Manot Cave, Israel. The dates confirm that the Early Ahmarian industry was present by 46,000 calibrated years before the present (cal BP), and the Levantine Aurignacian occurred at least between 38,000 and 34,000 cal BP. This timing is consistent with proposed migrations or technological diffusions between the Near East and Europe. Specifically, the Ahmarian could have led to the development of the Protoaurignacian in Europe, and the Aurignacian in Europe could have spread back to the Near East as the Levantine Aurignacian.

YALE NATURAL RADIOCARBON MEASUREMENTS. PART VI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stuiver, M.; Deevey, E.S.

1961-01-01

Most of the measurements made since publication of Yale V are included; some measurements, such as a series collected in Greenland, are withneld pending additional information or field work that will make better interpretations possible. In addition to radiocarbon dates of geologic and/or archaeologic interest, recent assays are given of C/sup 14/ in lake waters and other lacustrine materials, now normalized for C/sup 13/ content. The newly accepted convention is followed in expressing normalized C/sup 14/ values as DELTA = delta C/sup 14/ (2 delta C/sup 13/ + 50)STAl + ( delta C/sup 14//1000)! where DELTA is the per milmore » deviation of the C/sup 14/ if the sample from any contemporary standard (whether organic or a carbonate) after correction of sample and/or standard for real age, for the Suess effect, for normal isotopic fractionation, and for deviations of C/sup 14/ content of the age- and pollution- corrected l9th-century wood standard from that of 95% of the NBS oxalic acid standard; delta C/sup 14/ is the measured deviation from 95% of the NBS standard, and delta C/sup 13/ is the deviation from the NBS limestone standard, both in per mil. These assays are variously affected by artificial C/sup 14/ resulting from nuclear tests. (auth)« less

The Remarkable Metrological History of Radiocarbon Dating [II].

PubMed

Currie, Lloyd A

2004-01-01

This article traces the metrological history of radiocarbon, from the initial breakthrough devised by Libby, to minor (evolutionary) and major (revolutionary) advances that have brought (14)C measurement from a crude, bulk [8 g carbon] dating tool, to a refined probe for dating tiny amounts of precious artifacts, and for "molecular dating" at the 10 µg to 100 µg level. The metrological advances led to opportunities and surprises, such as the non-monotonic dendrochronological calibration curve and the "bomb effect," that gave rise to new multidisciplinary areas of application, ranging from archaeology and anthropology to cosmic ray physics to oceanography to apportionment of anthropogenic pollutants to the reconstruction of environmental history. Beyond the specific topic of natural (14)C, it is hoped that this account may serve as a metaphor for young scientists, illustrating that just when a scientific discipline may appear to be approaching maturity, unanticipated metrological advances in their own chosen fields, and unanticipated anthropogenic or natural chemical events in the environment, can spawn new areas of research having exciting theoretical and practical implications.

The Remarkable Metrological History of Radiocarbon Dating [II

PubMed Central

Currie, Lloyd A.

2004-01-01

This article traces the metrological history of radiocarbon, from the initial breakthrough devised by Libby, to minor (evolutionary) and major (revolutionary) advances that have brought 14C measurement from a crude, bulk [8 g carbon] dating tool, to a refined probe for dating tiny amounts of precious artifacts, and for “molecular dating” at the 10 µg to 100 µg level. The metrological advances led to opportunities and surprises, such as the non-monotonic dendrochronological calibration curve and the “bomb effect,” that gave rise to new multidisciplinary areas of application, ranging from archaeology and anthropology to cosmic ray physics to oceanography to apportionment of anthropogenic pollutants to the reconstruction of environmental history. Beyond the specific topic of natural 14C, it is hoped that this account may serve as a metaphor for young scientists, illustrating that just when a scientific discipline may appear to be approaching maturity, unanticipated metrological advances in their own chosen fields, and unanticipated anthropogenic or natural chemical events in the environment, can spawn new areas of research having exciting theoretical and practical implications. PMID:27366605

Radiocarbon Dating and Wood Density Chronologies of Mangrove Trees in Arid Western Australia

PubMed Central

Santini, Nadia S.; Hua, Quan; Schmitz, Nele; Lovelock, Catherine E.

2013-01-01

Mangrove trees tend to be larger and mangrove communities more diverse in tropical latitudes, particularly where there is high rainfall. Variation in the structure, growth and productivity of mangrove forests over climatic gradients suggests they are sensitive to variations in climate, but evidence of changes in the structure and growth of mangrove trees in response to climatic variation is scarce. Bomb-pulse radiocarbon dating provides accurate dates of recent wood formation and tree age of tropical and subtropical tree species. Here, we used radiocarbon techniques combined with X-ray densitometry to develop a wood density chronology for the mangrove Avicennia marina in the Exmouth Gulf, Western Australia (WA). We tested whether wood density chronologies of A. marina were sensitive to variation in the Pacific Decadal Oscillation Index, which reflects temperature fluctuations in the Pacific Ocean and is linked to the instrumental rainfall record in north WA. We also determined growth rates in mangrove trees from the Exmouth Gulf, WA. We found that seaward fringing A. marina trees (∼10 cm diameter) were 48±1 to 89±23 years old (mean ± 1σ) and that their growth rates ranged from 4.08±2.36 to 5.30±3.33 mm/yr (mean ±1σ). The wood density of our studied mangrove trees decreased with increases in the Pacific Decadal Oscillation Index. Future predicted drying of the region will likely lead to further reductions in wood density and their associated growth rates in mangrove forests in the region. PMID:24265797

Radiocarbon dating and wood density chronologies of mangrove trees in arid Western Australia.

PubMed

Santini, Nadia S; Hua, Quan; Schmitz, Nele; Lovelock, Catherine E

2013-01-01

Mangrove trees tend to be larger and mangrove communities more diverse in tropical latitudes, particularly where there is high rainfall. Variation in the structure, growth and productivity of mangrove forests over climatic gradients suggests they are sensitive to variations in climate, but evidence of changes in the structure and growth of mangrove trees in response to climatic variation is scarce. Bomb-pulse radiocarbon dating provides accurate dates of recent wood formation and tree age of tropical and subtropical tree species. Here, we used radiocarbon techniques combined with X-ray densitometry to develop a wood density chronology for the mangrove Avicennia marina in the Exmouth Gulf, Western Australia (WA). We tested whether wood density chronologies of A. marina were sensitive to variation in the Pacific Decadal Oscillation Index, which reflects temperature fluctuations in the Pacific Ocean and is linked to the instrumental rainfall record in north WA. We also determined growth rates in mangrove trees from the Exmouth Gulf, WA. We found that seaward fringing A. marina trees (~10 cm diameter) were 48 ± 1 to 89 ± 23 years old (mean ± 1 σ) and that their growth rates ranged from 4.08 ± 2.36 to 5.30 ± 3.33 mm/yr (mean ± 1 σ). The wood density of our studied mangrove trees decreased with increases in the Pacific Decadal Oscillation Index. Future predicted drying of the region will likely lead to further reductions in wood density and their associated growth rates in mangrove forests in the region.

Radiocarbon ages of pre-bomb clams and the hard-water effect in Lakes Michigan and Huron

USGS Publications Warehouse

Rea, David K.; Colman, Steven M.

1995-01-01

Five radiocarbon ages, all determined by accelerator mass spectrometry, have been obtained for two pre-bomb bivalves from Lake Michigan and one from Lake Huron. After correcting those ages for the fractionation of14C in calcite and for the radioactively inert CO2 in the atmosphere, we find residual ages, caused by the hard water effect, of about 250 years for Lake Michigan and 440 years for Lake Huron.

Radial ooids from Great Salt Lake (Utah) as paleoenvironmental archives: Insights from radiocarbon chronology and stable isotopes

NASA Astrophysics Data System (ADS)

Paradis, O. P.; Corsetti, F. A.; Bardsley, A.; Hammond, D. E.; Xu, X.; Walker, J. C.

2017-12-01

Ooids (laminated, carbonate coated grains) are ubiquitous in the geologic record in marine and lacustrine settings, and thus remain a common target for geochemical analysis to understand modern and ancient aqueous environments. However, the processes governing ooid formation remain unclear. Recently, radiocarbon dating has revealed that modern marine ooids grow slowly (Beaupre et al. 2015), and laboratory experiments have highlighted the importance of sediment transport and abrasion on net growth rates and ooid size (Trower et al. 2017). Ooid cortex structure includes micritic, tangential and/or radially oriented fabrics. Most modern marine ooids have tangential or micritic cortices, whereas many ancient ooids have radial cortices—thus, there is a need to understand how radial ooids in ancient rocks might inform us about their depositional environment. The Great Salt Lake (GSL), Utah, provides a unique environment to assess the growth rate of primary radial aragonitic ooids. Ooids collected near Antelope Island in the south arm of GSL were sieved, the 355-500 µm fraction was sequentially leached, and 14C of the evolved gas was analyzed to provide a time series of growth. The oldest inorganic carbon of this size fraction has an apparent 14C age of 6600 yr BP, with subsequent growth spanning over 6,000 years. Closed-basin lakes are particularly susceptible to a "reservoir effect" which results in anomalously old apparent radiocarbon ages. The 14C age of the modern dissolved inorganic carbon (DIC) of the south arm was measured to be 295 yr BP, a reservoir age comparable to estimates from lacustrine cave carbonates (McGee et al. 2012). Net growth rate of south arm ooids ranges between 0.01-0.025 µm per year. The δ13C of the outermost cortex suggests that the ooids resemble the modern DIC in the south arm water, suggesting ooids precipitate in equilibrium with lake water. Finer-scale structure in the δ13C of the ooid cortex through time suggests lake level changed

Radiocarbon dating of archaeological samples (sambaqui) using CO(2) absorption and liquid scintillation spectrometry of low background radiation.

PubMed

Mendonça, Maria Lúcia T G; Godoy, José M; da Cruz, Rosana P; Perez, Rhoneds A R

2006-01-01

Sambaqui means, in the Tupi language, a hill of shells. The sambaquis are archaeological sites with remains of pre-historical Brazilian occupation. Since the sambaqui sites in the Rio de Janeiro state region are older than 10,000 years, the applicability of CO(2) absorption on Carbo-sorb and (14)C determination by counting on a low background liquid scintillation counter was tested. In the present work, sambaqui shells were treated with H(3)PO(4) in a closed vessel in order to generate CO(2). The produced CO(2) was absorbed on Carbo-sorb. On saturation about 0.6g of carbon, as CO(2), was mixed with commercial liquid scintillation cocktail (Permafluor), and the (14)C activity determined by counting on a low background counter, Packard Tricarb 3170 TR/SL, for a period of 1000 mins to enable detection of a radiocarbon age of 22,400 BP. But only samples with ages up to 3500 BP were submitted to the method because the samples had been collected in the municipality of Guapimirim, in archaeological sambaqui-type sites belonging to this age range. The same samples were sent to the (14)C Laboratory of the Centro de Energia Nuclear na Agricultura (CENA/USP) where similar results were obtained.

Recent sediment remolding on a deep shelf, Ross Sea: implications for radiocarbon dating of Antarctic marine sediments

NASA Astrophysics Data System (ADS)

Domack, Eugene W.; Taviani, Marco; Rodriguez, Anthonio

1999-11-01

Coarse, bioclastic rich sands have been widely reported from the banks of the Antarctic continental shelf but their origin is still poorly known. We report on a suite of coarse sediments recovered from the top of the Mawson Bank in the northwestern Ross Sea. Radiocarbon ages of biogenic calcite, for modern and apparently late Pleistocene deposits, range from 1085±45 to 20,895±250 yr B.P.. Discovery of soft tissue (Ascidian) preserved as an incrustation on a pebble at 2 m depth indicates aggregation of the sediment within several months or a year of core recovery. Radiocarbon ages of acid insoluble organic matter (aiom) are less than those of the foraminifera calcite. The aiom ages are also reversed in sequence, indicating reworking of the sediment during deposition. These observations and a review of recently published literature suggest that much of the bank top sediment in Antarctica is presently undergoing remobilization, under the influence of strong currents and/or icebergs even under interglacical (high-stand) sea levels. These observations point out the need for careful, integrated studies on high latitude marine sediment cores before resultant "ages" alone are used as the foundation for paleoglacial reconstructions.

Towards an Absolute Chronology for the Aegean Iron Age: New Radiocarbon Dates from Lefkandi, Kalapodi and Corinth

PubMed Central

Toffolo, Michael B.; Fantalkin, Alexander; Lemos, Irene S.; Felsch, Rainer C. S.; Niemeier, Wolf-Dietrich; Sanders, Guy D. R.; Finkelstein, Israel; Boaretto, Elisabetta

2013-01-01

The relative chronology of the Aegean Iron Age is robust. It is based on minute stylistic changes in the Submycenaean, Protogeometric and Geometric styles and their sub-phases. Yet, the absolute chronology of the time-span between the final stages of Late Helladic IIIC in the late second millennium BCE and the archaic colonization of Italy and Sicily toward the end of the 8th century BCE lacks archaeological contexts that can be directly related to events carrying absolute dates mentioned in Egyptian/Near Eastern historical sources, or to well-dated Egyptian/Near Eastern rulers. The small number of radiocarbon dates available for this time span is not sufficient to establish an absolute chronological sequence. Here we present a new set of short-lived radiocarbon dates from the sites of Lefkandi, Kalapodi and Corinth in Greece. We focus on the crucial transition from the Submycenaean to the Protogeometric periods. This transition is placed in the late 11th century BCE according to the Conventional Aegean Chronology and in the late 12th century BCE according to the High Aegean Chronology. Our results place it in the second half of the 11th century BCE. PMID:24386150

On radiocarbon and plutonium leakage to groundwater in the vicinity of a shallow-land radioactive waste repository.

PubMed

Gudelis, A; Gvozdaite, R; Kubareviciene, V; Druteikiene, R; Lukosevicius, S; Sutas, A

2010-06-01

A shallow-land radioactive waste repository operated in boggy forest environment from 1963 to 1989. During the operation period, a considerable amount of technogenic radionuclides, in solidified state, was disposed into the vault established in the geological structure at the depth of up to 3m. Environmental monitoring activities started after the closure of the repository in 1989. Recent investigations revealed transfer of radiocarbon and plutonium to the groundwater in the prevailing flow direction. Activity concentration of (239,240)Pu in non-filtered fraction of the groundwater from observation well no. 4 determined by alpha-spectrometry was 6.4 x 10(-5) Bq l(-1) in 2005, and 3.2 x 10(-4) Bq l(-1) in 2006. Further analysis of colloid-facilitated transport of plutonium is planned. Variation of (14)C activity concentration in the same well was monitored in 2006. It varied from 0.2+/-0.1 Bq l(-1) in October to 2.8+/-0.6 Bq l(-1) in June and July. Results imply further research into radiocarbon transfer to atmosphere and selected plant species. Copyright (c) 2008 Elsevier Ltd. All rights reserved.

Comment on "Radiocarbon Calibration Curve Spanning 0 to 50,000 Years B.P. Based on Paired 230Th/234U/238U and 14C Dates on Pristine Corals" by R.G. Fairbanks, R. A. Mortlock, T.-C. Chiu, L. Cao, A. Kaplan, T. P. Guilderson, T. W. Fairbanks, A. L. Bloom, P

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reimer, P J; Baillie, M L; Bard, E

2005-10-02

Radiocarbon calibration curves are essential for converting radiocarbon dated chronologies to the calendar timescale. Prior to the 1980's numerous differently derived calibration curves based on radiocarbon ages of known age material were in use, resulting in ''apples and oranges'' comparisons between various records (Klein et al., 1982), further complicated by until then unappreciated inter-laboratory variations (International Study Group, 1982). The solution was to produce an internationally-agreed calibration curve based on carefully screened data with updates at 4-6 year intervals (Klein et al., 1982; Stuiver and Reimer, 1986; Stuiver and Reimer, 1993; Stuiver et al., 1998). The IntCal working group hasmore » continued this tradition with the active participation of researchers who produced the records that were considered for incorporation into the current, internationally-ratified calibration curves, IntCal04, SHCal04, and Marine04, for Northern Hemisphere terrestrial, Southern Hemisphere terrestrial, and marine samples, respectively (Reimer et al., 2004; Hughen et al., 2004; McCormac et al., 2004). Fairbanks et al. (2005), accompanied by a more technical paper, Chiu et al. (2005), and an introductory comment, Adkins (2005), recently published a ''calibration curve spanning 0-50,000 years''. Fairbanks et al. (2005) and Chiu et al. (2005) have made a significant contribution to the database on which the IntCal04 and Marine04 calibration curves are based. These authors have now taken the further step to derive their own radiocarbon calibration extending to 50,000 cal BP, which they claim is superior to that generated by the IntCal working group. In their papers, these authors are strongly critical of the IntCal calibration efforts for what they claim to be inadequate screening and sample pretreatment methods. While these criticisms may ultimately be helpful in identifying a better set of protocols, we feel that there are also several erroneous and misleading

RADIOCARBON DATING: A CASE AGAINST THE PROPOSED LINK BETWEEN RIVER MOLLUSKS AND SOIL HUMUS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Broecker, W.

The C/sup 14/ link between river mollusks and soil humus is discussed. It is stated that the explanation that the C/sup 13/ deficiency should be attributed to the uptake of soil CO/sub 2/ by ground water (oxidation of humus in the soil, rather than after it has been transported into streams) and the C/sup 14/ deficiency to the solution of limestone is far more plausible. It was concluded that any relation between the radiocarbon concentrations in soil humus and fresh water mollusks is almost certainly coincidental. (P.C.H.)

Solar activity around AD 775 from aurorae and radiocarbon

NASA Astrophysics Data System (ADS)

Neuhäuser, R.; Neuhäuser, D. L.

2015-04-01

A large variation in 14C around AD 775 has been considered to be caused by one or more solar super-flares within one year. We critically review all known aurora reports from Europe as well as the Near, Middle, and Far East from AD 731 to 825 and find 39 likely true aurorae plus four more potential aurorae and 24 other reports about halos, meteors, thunderstorms etc., which were previously misinterpreted as aurorae or misdated; we assign probabilities for all events according to five aurora criteria. We find very likely true aurorae in AD 743, 745, 762, 765, 772, 773, 793, 796, 807, and 817. There were two aurorae in the early 770s observed near Amida (now Diyarbak\\i r in Turkey near the Turkish-Syrian border), which were not only red, but also green-yellow - being at a relatively low geomagnetic latitude, they indicate a relatively strong solar storm. However, it cannot be argued that those aurorae (geomagnetic latitude 43 to 50°, considering five different reconstructions of the geomagnetic pole) could be connected to one or more solar super-flares causing the 14C increase around AD 775: There are several reports about low- to mid-latitude aurorae at 32 to 44° geomagnetic latitude in China and Iraq; some of them were likely observed (quasi-)simultaneously in two of three areas (Europe, Byzantium/Arabia, East Asia), one lasted several nights, and some indicate a particularly strong geomagnetic storm (red colour and dynamics), namely in AD 745, 762, 793, 807, and 817 - always without 14C peaks. We use 39 likely true aurorae as well as historic reports about sunspots together with the radiocarbon content from tree rings to reconstruct the solar activity: From AD {˜ 733} to {˜ 823}, we see at least nine Schwabe cycles; instead of one of those cycles, there could be two short, weak cycles - reflecting the rapid increase to a high 14C level since AD 775, which lies at the end of a strong cycle. In order to show the end of the dearth of naked-eye sunspots, we

Oral health attitudes and behavior of dental students at the University of Zagreb, Croatia.

PubMed

Badovinac, Ana; Božić, Darko; Vučinac, Ivana; Vešligaj, Jasna; Vražić, Domagoj; Plancak, Darije

2013-09-01

The aim of this study was to investigate oral health behavior and attitudes of dental students in years 1 to 6 at the University of Zagreb, Croatia. The Croatian version of the Hiroshima University-Dental Behavioral Inventory (HU-DBI) was administered to predoctoral dental students, and collected data were analyzed. A total of 503 students (22.3 ± 2.6 mean age) completed the questionnaire. The response rate was 85.1 percent, and 72.4 percent of the respondents were female. These dental students' answers to eleven out of twenty HU-DBI items differed significantly by academic year. The mean questionnaire score was 6.62 ± 1.54, and the highest value of the HU-DBI score was in the fourth year (7.24 ± 1.54). First-year students were most likely to have a toothbrush with hard bristles and felt they had not brushed well unless done with hard strokes. Students in the sixth year were least worried about visiting a dentist and most frequently put off going to a dentist until having a toothache, indicating that rise of knowledge contributes to higher self-confidence. The mean HU-DBI score for these students showed average value, pointing out the need for a comprehensive oral hygiene and preventive program from the start of dental school.

Joint and fascial chronic graft-vs-host disease: correlations with clinical and laboratory parameters

PubMed Central

Vukić, Tamara; Smith, Sean Robinson; Ljubas Kelečić, Dina; Desnica, Lana; Prenc, Ema; Pulanić, Dražen; Vrhovac, Radovan; Nemet, Damir; Pavletic, Steven Z.

2016-01-01

Aim To determine if there are correlations between joint and fascial chronic graft-vs-host disease (cGVHD) with clinical findings, laboratory parameters, and measures of functional capacity. Methods 29 patients were diagnosed with cGVHD based on National Institutes of Health (NIH) Consensus Criteria at the University Hospital Centre Zagreb from October 2013 to October 2015. Physical examination, including functional measures such as 2-minute walk test and hand grip strength, as well as laboratory tests were performed. The relationship between these evaluations and the severity of joint and fascial cGVHD was tested by logistical regression analysis. Results 12 of 29 patients (41.3%) had joint and fascial cGVHD diagnosed according to NIH Consensus Criteria. There was a significant positive correlation of joint and fascial cGVHD and skin cGVHD (P < 0.001), serum C3 complement level (P = 0.045), and leukocytes (P = 0.032). There was a significant negative correlation between 2-minute walk test (P = 0.016), percentage of cytotoxic T cells CD3+/CD8+ (P = 0.022), serum albumin (P = 0.047), and Karnofsky score (P < 0.001). Binary logistic regression model found that a significant predictor for joint and fascial cGVHD was cGVHD skin involvement (odds ratio, 7.79; 95 confidence interval 1.87-32.56; P = 0.005). Conclusion Joint and fascial cGVHD manifestations correlated with multiple laboratory measurements, clinical features, and cGVHD skin involvement, which was a significant predictor for joint and fascial cGVHD. PMID:27374828

Opportunities in low-level radiocarbon microtracing: applications and new technology

PubMed Central

Vuong, Le Thuy; Song, Qi; Lee, Hee Joo; Roffel, Ad F; Shin, Seok-Ho; Shin, Young G; Dueker, Stephen R

2016-01-01

14C-radiolabeled (radiocarbon) drug studies are central to defining the disposition of therapeutics in clinical development. Concerns over radiation, however, have dissuaded investigators from conducting these studies as often as their utility may merit. Accelerator mass spectrometry (AMS), originally designed for carbon dating and geochronology, has changed the outlook for in-human radiolabeled testing. The high sensitivity of AMS affords human clinical testing with vastly reduced radiative (microtracing) and chemical exposures (microdosing). Early iterations of AMS were unsuitable for routine biomedical use due to the instruments’ large size and associated per sample costs. The situation is changing with advances in the core and peripheral instrumentation. We review the important milestones in applied AMS research and recent advances in the core technology platform. We also look ahead to an entirely new class of 14C detection systems that use lasers to measure carbon dioxide in small gas cells. PMID:28031933

Accelerator radiocarbon dating of evidence for prehistoric horticulture in Illinois

USGS Publications Warehouse

Conard, N.; Asch, D.L.; Asch, N.B.; Elmore, D.; Gove, H.; Rubin, M.; Brown, J.A.; Wiant, M.D.; Farnsworth, K.B.; Cook, T.G.

1984-01-01

With the development of direct detection radiocarbon dating, which uses an accelerator as part of a highly selective mass spectrometer, it is now possible to determine the age of milligram samples of organic materials1-5. One application of accelerator dating is in evaluating scanty, sometimes controversial evidence for early horticulture throughout the world. We have now used the technique to date small samples of carbonized, cultivated plant remains from archaeological sites in Illinois. The results, reported here, establish (1) that squash was introduced by 7,000 yr ago, 2,500 yr before eastern North American records previously reported; (2) that horticulture involving indigenous plants had begun by 4,000 BP in eastern North America with domestication of Iva annua, a small-seeded annual; (3) that anomalous discoveries of Archaic period maize represent contaminants; and (4) that introduction of maize by initial Middle Woodland times (~2,000 BP) is questionable.

Anomalous elevated radiocarbon measurements of PM2.5

NASA Astrophysics Data System (ADS)

Buchholz, Bruce A.; Fallon, Stewart J.; Zermeño, Paula; Bench, Graham; Schichtel, Bret A.

2013-01-01

Two-component models are often used to determine the contributions made by fossil fuel and natural sources of carbon in airborne particulate matter (PM). The models reduce thousands of actual sources to two end members based on isotopic signature. Combustion of fossil fuels produces PM free of carbon-14 (14C). Wood or charcoal smoke, restaurant fryer emissions, and natural emissions from plants produce PM with the contemporary concentration of 14C approximately 1.2 × 10-1214C/C. Such data can be used to estimate the relative contributions of fossil fuels and biogenic aerosols to the total aerosol loading and radiocarbon analysis is becoming a popular source apportionment method. Emissions from incinerators combusting medical or biological wastes containing tracer 14C can skew the 14C/C ratio of PM, however, so critical analysis of sampling sites for possible sources of elevated PM needs to be completed prior to embarking on sampling campaigns. Results are presented for two ambient monitoring sites in different areas of the United States where 14C contamination is apparent. Our experience suggests that such contamination is uncommon but is also not rare (∼10%) for PM sampling sites.

Radiocarbon and DNA evidence for a pre-Columbian introduction of Polynesian chickens to Chile

PubMed Central

Storey, Alice A.; Ramírez, José Miguel; Quiroz, Daniel; Burley, David V.; Addison, David J.; Walter, Richard; Anderson, Atholl J.; Hunt, Terry L.; Athens, J. Stephen; Huynen, Leon; Matisoo-Smith, Elizabeth A.

2007-01-01

Two issues long debated among Pacific and American prehistorians are (i) whether there was a pre-Columbian introduction of chicken (Gallus gallus) to the Americas and (ii) whether Polynesian contact with South America might be identified archaeologically, through the recovery of remains of unquestionable Polynesian origin. We present a radiocarbon date and an ancient DNA sequence from a single chicken bone recovered from the archaeological site of El Arenal-1, on the Arauco Peninsula, Chile. These results not only provide firm evidence for the pre-Columbian introduction of chickens to the Americas, but strongly suggest that it was a Polynesian introduction. PMID:17556540

Radiocarbon and DNA evidence for a pre-Columbian introduction of Polynesian chickens to Chile.

PubMed

Storey, Alice A; Ramírez, José Miguel; Quiroz, Daniel; Burley, David V; Addison, David J; Walter, Richard; Anderson, Atholl J; Hunt, Terry L; Athens, J Stephen; Huynen, Leon; Matisoo-Smith, Elizabeth A

2007-06-19

Two issues long debated among Pacific and American prehistorians are (i) whether there was a pre-Columbian introduction of chicken (Gallus gallus) to the Americas and (ii) whether Polynesian contact with South America might be identified archaeologically, through the recovery of remains of unquestionable Polynesian origin. We present a radiocarbon date and an ancient DNA sequence from a single chicken bone recovered from the archaeological site of El Arenal-1, on the Arauco Peninsula, Chile. These results not only provide firm evidence for the pre-Columbian introduction of chickens to the Americas, but strongly suggest that it was a Polynesian introduction.

Source Apportionment of Background PAHs in the Peace-Athabasca Delta (Alberta, Canada) Using Molecular Level Radiocarbon Analysis.

PubMed

Jautzy, Josué J; Ahad, Jason M E; Hall, Roland I; Wiklund, Johan A; Wolfe, Brent B; Gobeil, Charles; Savard, Martine M

2015-08-04

The downstream accumulation of polycyclic aromatic hydrocarbons (PAHs) in the Peace-Athabasca Delta (PAD), an ecologically important landscape, is a key issue of concern given the rapid development of the oil sands industry in Northern Alberta, Canada. In addition to PAHs derived from industrial activity (i.e., oil sands mining) within the Athabasca watershed, however, forest fires and erosion of fossil fuel deposits within both the Athabasca and Peace watersheds are two potentially important natural sources of PAHs delivered to the PAD. Consequently, evaluating the environmental impact of mining activities requires a quantitative understanding of natural, background PAHs. Here, we utilize molecular-level natural-abundance radiocarbon measurements on an amalgamated sediment record from a Peace River flood-susceptible oxbow lake in the northern Peace sector of the PAD to quantitatively discriminate sources of naturally occurring alkylated PAHs (fossil and modern biomass). A radiocarbon mass balance quantified a predominantly natural petrogenic source (93% petrogenic, 7% forest fire) for alkylated PAHs during the past ∼50 years. Additionally, a significant petrogenic component determined for retene, a compound usually considered a biomarker for softwood combustion, suggests that its use as a unique forest fire indicator may not be suitable in PAD sediments receiving Peace watershed-derived fluvial inputs.

[Laboratory findings in patients with hemorrhagic fever with renal syndrome].

PubMed

Puljiz, Ivan; Kuzman, Ilija; Turcinov, Drago; Makek, Nikola; Markotić, Alemka

2005-01-01

To examine the frequency and distribution of hematologic and biochemical laboratory findings in 94 patients with hemorrhagic fever with renal syndrome (HFRS) in the epidemic year 2002. The following laboratory findings were retrospectively analyzed: erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), hemoglobin, hematocrit, leukocyte count and differential percentage (segmented neutrophils, band neutrophils, atypical lymphocytes), platelet count, coagulation tests, blood urea nitrogen (BUN), creatinine, urine, potassium, bilirubin (BIL), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltransferase (GT), alkaline phosphatase (ALP), and serum protein electrophoresis. The study included 94 HFRS patients treated at the Dr Fran Mihaljević University Hospital for Infectious Diseases in Zagreb during 2002. ESR increase, mostly mild to moderate, was found in 86.2% of study patients. Increased CRP was recorded in 98.9% of study patients, however, one-fourth had CRP higher than 100 mg/L. Leukocytosis was recorded in 38.3% (10.1 +/- 4.2 x 10(9)/L), thrombocytopenia in 89.4% patients (68.2 +/- 48.3 x 10(9)/L), and severe thrombocytopenia (x 10(9)/L) in six patients. Three patients had abnormal coagulation tests. Increased values of BUN and creatinine were recorded in more than a half of patients, while only four patients had mild hyperkalemia. Only three patinets required hemodialysis. Mildly to moderately increased values of aminotransferases (AST, ALT, GT) were observed in more than 2/3; hypoalbuminaemia in nearly 1/3, and elevated alpha-2 fraction in more than 2/3 of patients. The majority of patients had pathologic urine findings. First laboratory abnormalities were usually found between day 5 and 7 of the disease (increased CRP level, thrombocytopenia, leukocytosis, and elevation of hemoglobin and hematocrit). Biochemical abnormalities(elevation of cratinine and urea, increased levels of aminotransferases) usually occurred at

Combined use of radiocarbon and stable carbon isotope to constrain the sources and cycling of particulate organic carbon in a large freshwater lake, China.

PubMed

Chen, Jingan; Yang, Haiquan; Zeng, Yan; Guo, Jianyang; Song, Yilong; Ding, Wei

2018-06-01

The concentrations and isotopic compositions of dissolved inorganic carbon (DIC) and particulate organic carbon (POC) were measured in order to better constrain the sources and cycling of POC in Lake Fuxian, the largest deep freshwater lake in China. Model results based on the combined δ 13 C and Δ 14 C, showed that the average lake-wide contributions of autochthonous POC, terrestrial POC, and resuspended sediment POC to the bulk POC in Lake Fuxian were 61%, 22%, and 17%, respectively. This indicated autochthonous POC might play a dominant role in sustaining large oligotrophic lake ecosystem. A mean 17% contribution of resuspended sediment POC to the bulk POC implied that sediment might have more significant influence on aquatic environment and ecosystem than previously recognized in large deep lakes. The contributions of different sources POC to the water-column POC were a function of the initial composition of the source materials, photosynthesis, physical regime of the lake, sediment resuspension, respiration and degradation of organic matter, and were affected indirectly by environmental factors such as light, temperature, DO, wind speed, turbidity, and nutrient concentration. This study is not only the first systematic investigation on the radiocarbon and stable isotope compositions of POC in large deep freshwater lake in China, but also one of the most extensive radiocarbon studies on the ecosystem of any great lakes in the world. The unique data constrain relative influences of autochthonous POC, terrestrial POC, and resuspended sediment POC, and deepen the understanding of the POC cycling in large freshwater lakes. This study is far from comprehensive, but it serves to highlight the potential of combined radiocarbon and stable carbon isotope for constraining the sources and cycling of POC in large lake system. More radiocarbon investigations on the water-column POC and the aquatic food webs are necessary to illuminate further the fate of autochthonous POC

77 FR 75663 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-Telemanagement Forum

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-21

...; University of Zagreb, Faculty of Electrical Engineering and Computing, Zagreb, CROATIA; University of Zagreb, Faculty of Transport and Traffic Sciences, Zagreb, CROATIA; EPAEON LTD, Nicosia, CYPRUS; UNIVERSITY OF... Costarricense S.A, San Jose, COSTA RICA; University of Zagreb to University of Zagreb, Faculty of Electrical...

Single amino acid radiocarbon dating of Upper Paleolithic modern humans

PubMed Central

Marom, Anat; McCullagh, James S. O.; Higham, Thomas F. G.; Sinitsyn, Andrey A.; Hedges, Robert E. M.

2012-01-01

Archaeological bones are usually dated by radiocarbon measurement of extracted collagen. However, low collagen content, contamination from the burial environment, or museum conservation work, such as addition of glues, preservatives, and fumigants to “protect” archaeological materials, have previously led to inaccurate dates. These inaccuracies in turn frustrate the development of archaeological chronologies and, in the Paleolithic, blur the dating of such key events as the dispersal of anatomically modern humans. Here we describe a method to date hydroxyproline found in collagen (∼10% of collagen carbon) as a bone-specific biomarker that removes impurities, thereby improving dating accuracy and confidence. This method is applied to two important sites in Russia and allows us to report the earliest direct ages for the presence of anatomically modern humans on the Russian Plain. These dates contribute considerably to our understanding of the emergence of the Mid-Upper Paleolithic and the complex suite of burial behaviors that begin to appear during this period. PMID:22517758

Single amino acid radiocarbon dating of Upper Paleolithic modern humans.

PubMed

Marom, Anat; McCullagh, James S O; Higham, Thomas F G; Sinitsyn, Andrey A; Hedges, Robert E M

2012-05-01

Archaeological bones are usually dated by radiocarbon measurement of extracted collagen. However, low collagen content, contamination from the burial environment, or museum conservation work, such as addition of glues, preservatives, and fumigants to "protect" archaeological materials, have previously led to inaccurate dates. These inaccuracies in turn frustrate the development of archaeological chronologies and, in the Paleolithic, blur the dating of such key events as the dispersal of anatomically modern humans. Here we describe a method to date hydroxyproline found in collagen (~10% of collagen carbon) as a bone-specific biomarker that removes impurities, thereby improving dating accuracy and confidence. This method is applied to two important sites in Russia and allows us to report the earliest direct ages for the presence of anatomically modern humans on the Russian Plain. These dates contribute considerably to our understanding of the emergence of the Mid-Upper Paleolithic and the complex suite of burial behaviors that begin to appear during this period.

Attitudes of Students of Differenet Schools of University of Zagreb on Tooth Bleaching.

PubMed

Diklić, Dinka; Sever, Eva Klarić; Galić, Nada; Spajić, Jelena; Prskalo, Katica

2016-12-01

To compare the awareness that students from four different faculties within the University of Zagreb have of oral health and tooth bleaching procedure. The study included 158 subjects (both male and female) - 38 students from the School of Dental Medicine and 40 students from each of the following faculties: the School of Medicine, the Faculty of Economics and the Faculty of Civil Engineering. The respondents were asked to fill out the survey with multiple choices by marking the answers they considered correct. Only 12% of the respondents followed the information on oral health. More than two thirds of all subjects brush their teeth twice a day, but there were no statistically significant differences between the subjects with respect to college or gender. More than half of the participants (55%) were satisfied, and 12% were completely satisfied with their dental appearance. About 80% of the respondents were aware of differences between teeth bleaching and teeth polishing procedures, with greater prevalence among Dental Medicine and Medicine students. 80% of all subjects would go to a dental office if they decided to whiten their teeth while less than a half (46%) of all the subjects believed that a tooth bleaching has some adverse side-effects. There is a difference in knowledge on oral hygiene and tooth bleaching between the students from the School of Dental Medicine, the School of Medicine, the Faculty of Economics and those from the Faculty of Civil Engineering. Dental students have the best knowledge on tooth bleaching and oral health, which was in accordance with their educational guidance and level of education.

Radiocarbon dating uncertainty and the reliability of the PEWMA method of time-series analysis for research on long-term human-environment interaction

PubMed Central

Carleton, W. Christopher; Campbell, David

2018-01-01

Statistical time-series analysis has the potential to improve our understanding of human-environment interaction in deep time. However, radiocarbon dating—the most common chronometric technique in archaeological and palaeoenvironmental research—creates challenges for established statistical methods. The methods assume that observations in a time-series are precisely dated, but this assumption is often violated when calibrated radiocarbon dates are used because they usually have highly irregular uncertainties. As a result, it is unclear whether the methods can be reliably used on radiocarbon-dated time-series. With this in mind, we conducted a large simulation study to investigate the impact of chronological uncertainty on a potentially useful time-series method. The method is a type of regression involving a prediction algorithm called the Poisson Exponentially Weighted Moving Average (PEMWA). It is designed for use with count time-series data, which makes it applicable to a wide range of questions about human-environment interaction in deep time. Our simulations suggest that the PEWMA method can often correctly identify relationships between time-series despite chronological uncertainty. When two time-series are correlated with a coefficient of 0.25, the method is able to identify that relationship correctly 20–30% of the time, providing the time-series contain low noise levels. With correlations of around 0.5, it is capable of correctly identifying correlations despite chronological uncertainty more than 90% of the time. While further testing is desirable, these findings indicate that the method can be used to test hypotheses about long-term human-environment interaction with a reasonable degree of confidence. PMID:29351329

Radiocarbon dating uncertainty and the reliability of the PEWMA method of time-series analysis for research on long-term human-environment interaction.

PubMed

Carleton, W Christopher; Campbell, David; Collard, Mark

2018-01-01

Statistical time-series analysis has the potential to improve our understanding of human-environment interaction in deep time. However, radiocarbon dating-the most common chronometric technique in archaeological and palaeoenvironmental research-creates challenges for established statistical methods. The methods assume that observations in a time-series are precisely dated, but this assumption is often violated when calibrated radiocarbon dates are used because they usually have highly irregular uncertainties. As a result, it is unclear whether the methods can be reliably used on radiocarbon-dated time-series. With this in mind, we conducted a large simulation study to investigate the impact of chronological uncertainty on a potentially useful time-series method. The method is a type of regression involving a prediction algorithm called the Poisson Exponentially Weighted Moving Average (PEMWA). It is designed for use with count time-series data, which makes it applicable to a wide range of questions about human-environment interaction in deep time. Our simulations suggest that the PEWMA method can often correctly identify relationships between time-series despite chronological uncertainty. When two time-series are correlated with a coefficient of 0.25, the method is able to identify that relationship correctly 20-30% of the time, providing the time-series contain low noise levels. With correlations of around 0.5, it is capable of correctly identifying correlations despite chronological uncertainty more than 90% of the time. While further testing is desirable, these findings indicate that the method can be used to test hypotheses about long-term human-environment interaction with a reasonable degree of confidence.

An absolute chronology for early Egypt using radiocarbon dating and Bayesian statistical modelling

PubMed Central

Dee, Michael; Wengrow, David; Shortland, Andrew; Stevenson, Alice; Brock, Fiona; Girdland Flink, Linus; Bronk Ramsey, Christopher

2013-01-01

The Egyptian state was formed prior to the existence of verifiable historical records. Conventional dates for its formation are based on the relative ordering of artefacts. This approach is no longer considered sufficient for cogent historical analysis. Here, we produce an absolute chronology for Early Egypt by combining radiocarbon and archaeological evidence within a Bayesian paradigm. Our data cover the full trajectory of Egyptian state formation and indicate that the process occurred more rapidly than previously thought. We provide a timeline for the First Dynasty of Egypt of generational-scale resolution that concurs with prevailing archaeological analysis and produce a chronometric date for the foundation of Egypt that distinguishes between historical estimates. PMID:24204188

Geographic and temporal trends in proboscidean and human radiocarbon histories during the late Pleistocene

NASA Astrophysics Data System (ADS)

Ugan, Andrew; Byers, David

2007-12-01

The causes of large animal extinctions at the end of the Pleistocene remain a hotly debated topic focused primarily on the effects of human over hunting and climate change. Here we examine multiple, large radiocarbon data sets for humans and extinct proboscideans and explore how variation in their temporal and geographic distributions were related prior to proboscidean extinction. These data include 4532 archaeological determinations from Europe and Siberia and 1177 mammoth and mastodont determinations from Europe, Siberia, and North America. All span the period from 45,000 to 12,000 calendar years BP. We show that while the geographic ranges of dated human occupations and proboscidean remains overlap across the terminal Pleistocene of the Old World, the two groups remain largely segregated and increases in the frequency of human occupations do not coincide with declines in proboscidean remains. Prior to the Last Glacial Maximum (LGM; ca 21,000 years BP), archaeological 14C determinations increase slightly in frequency worldwide while the frequency of dated proboscidean remains varies depending on taxon and location. After the LGM, both sympatric and allopatric groups of humans and proboscideans increase sharply as climatic conditions ameliorate. Post-LGM radiocarbon frequencies among proboscideans peak at different times, also depending upon taxon and location. Woolly mammoths in Beringia reach a maximum and then decline beginning between 16,000 and 15,500 years BP, woolly mammoths in Europe and Siberia ca 14,500 and 13,500 BP, and Columbian mammoth and American mastodont only after 13,000 BP. Declines among woolly mammoths appear to coincide with the restructuring of biotic communities following the Pleistocene-Holocene transition.

Factors predisposing to early childhood caries (ECC) in children of pre-school age in the city of Zagreb, Croatia.

PubMed

Lulić-Dukić, O; Jurić, H; Dukić, W; Glavina, D

2001-06-01

The aim of this study was to investigate factors predisposing to early childhood caries (ECC) in pre-school children in the city of Zagreb, Croatia. The investigation was carried out on the sample of 145 children (77 boys and 68 girls) aged between 2 and 5 years, including clinical examination of dental status and survey on the habits among the parents. The overall prevalence of ECC was 30%: in girls it was 25%, and in boys 48%. The study on the risk factors was designed as a classic case-control study. The mean value of dmfs index among the cases amounted to 8.6, in comparison to 5.2 in the control group (p<0.05). Bottle-feeding did not represent a significant risk, but night consumption of sweet beverages after first 24 months and the lack of introduction of teeth-brushing habit after first 24 months did (p < 0.001 for both predictors). The study revealed the importance of early introduction of teeth-brushing and giving up the nightly consumption of sweet beverages in prevention of ECC.

Residence time revisited: The role of radiocarbon in reactive transport modeling

NASA Astrophysics Data System (ADS)

Lawrence, C. R.; Druhan, J. L.; Schulz, M. S.

2016-12-01

In recent years, our changing understanding of the dominant controls on soil carbon (C) storage and stability has cast a greater emphasis on the importance of physical and hydrological processes. These shifts in our understanding of C cycling have fostered increasingly commonplace measurements of soil physical and hydrological parameters in soil C studies (e.g. specific surface area, quantitative mineralogy, porosity) that reflect the importance of microbial accessibility to soil C. As a result, we are now poised to reassess the applicability of our approaches for conceptualizing and modeling soil C dynamics, particularly with regard to our representation of soil C pools. The goal of this work is to explore how the quantity and turnover of C, as approximated by radiocarbon measurements, is mechanistically linked to the physical and hydrologic parameters of soils. We utilize a reactive transport (RT) approach to link hydrologic transport, geochemical transformations and microbial activity influencing the magnitude and residence time of different carbon pools under variably saturated conditions. A newly developed version of the CrunchTope software is used to explicitly simulate the coupled transport, transformation, fractionation and decay of the three isotopes of carbon (12C, 13C and 14C) through a mechanistic framework. We constrain this model with a high-resolution dataset of soil carbon content, stable isotope composition and radiocarbon ages as well as physical and hydrologic data measured from a chronosequence of soils located near Santa Cruz, California. The Santa Cruz dataset is highly amenable to this task in that it demonstrates both seasonal and millennial variations in soil C distributions and associated soil properties. We present data from a series of simulations examining the sensitivity of C stocks, fluxes and mean residence times to transient processes spanning a range of temporal scales, including redox conditions, fluid flow and the distribution of

Radiocarbon-based impact assessment of open biomass burning on regional carbonaceous aerosols in North China.

PubMed

Zong, Zheng; Chen, Yingjun; Tian, Chongguo; Fang, Yin; Wang, Xiaoping; Huang, Guopei; Zhang, Fan; Li, Jun; Zhang, Gan

2015-06-15

Samples of total suspended particulates (TSPs) and fine particulate matter (PM2.5) were collected from 29th May to 1st July, 2013 at a regional background site in Bohai Rim, North China. Mass concentrations of particulate matter and carbonaceous species showed a total of 50% and 97% of the measured TSP and PM2.5 levels exceeded the first grade national standard of China, respectively. Daily concentrations of organic carbon (OC) and elemental carbon (EC) were detected 7.3 and 2.5 μg m(-3) in TSP and 5.2 and 2.0 μg m(-3) in PM2.5, which accounted 5.8% and 2.0% of TSP while 5.6% and 2.2% for PM2.5, respectively. The concentrations of OC, EC, TSP and PM2.5 were observed higher in the day time than those in the night time. The observations were associated with the emission variations from anthropogenic activities. Two merged samples representing from south and north source areas were selected for radiocarbon analysis. The radiocarbon measurements showed 74% of water-insoluble OC (WINSOC) and 59% of EC in PM2.5 derived from biomass burning and biogenic sources when the air masses were from south region, and 63% and 48% for the air masses from north, respectively. Combined with backward trajectories and daily burned area, open burning of agricultural wastes was found to be predominating, which was confirmed by the potential source contribution function (PSCF). Copyright © 2015 Elsevier B.V. All rights reserved.

Electronic Learning in Yugoslavia.

ERIC Educational Resources Information Center

Barker, Philip G.

1990-01-01

Describes a course taught at the University of Zagreb (Yugoslavia) on electronic learning methods based upon computer-assisted learning techniques. The course content is outlined, including lectures, workshops, videotapes, demonstration software, and courseware authoring; a multimedia teaching laboratory is described; and an evaluation of course…

Origin of PCDDs in ball clay assessed with compound-specific chlorine isotope analysis and radiocarbon dating.

PubMed

Holmstrand, Henry; Gadomski, Damien; Mandalakis, Manolis; Tysklind, Mats; Irvine, Robert; Andersson, Per; Gustafsson, Orjan

2006-06-15

Polychlorinated dibenzo-p-dioxins (PCDDs) of high concentrations in a ball clay deposit from the Mississippi Embayment were found to be consistent with a natural abiotic and non-pyrogenic origin by investigation with bulk radiocarbon analysis, compound-specific chlorine isotope analysis (CSIA-delta37Cl) of octachlorodibenzo-p-dioxin (OCDD), and black carbon (BC) analysis. The conventional radiocarbon date of total organic carbon from a depth of approximately 10 m in three parallel cores ranged from 14 700 years to >48 000 years, indicating that the strata with elevated levels of PCDDs have remained isolated from recent anthropogenic input in these >40 Ma old clay sediments. The CSIA-delta37Cl of OCDD yielded a delta37Cl of -0.2 per thousandth, which is significantly higher than the postulated range for biotic chlorination by chloroperoxidase enzymes, -11 to -10 per thousandth, and falls within the known range for abiotic organochlorines, -6 to +3 per thousandth. The absence of correlations between concentrations of PCDDs and corresponding pyrogenic black carbon (BC), together with estimations of BC sorptive loadings and the absence of polychlorinated dibenzofurans (PCDFs), suggest that vegetation fires did not form these ball-clay PCDDs. Results from this study indicate that the high levels of the toxic and carcinogenic PCDDs found in kaolinite-bearing clays may result from natural abiotic formation via in situ surface-promoted reactions on the clay mineral, including a so-far unknown organic precursor, rather than being the result of anthropogenic contamination.

Annual variability in the radiocarbon age and source of dissolved CO2 in a peatland stream.

PubMed

Garnett, Mark H; Dinsmore, Kerry J; Billett, Michael F

2012-06-15

Radiocarbon dating has the capacity to significantly improve our understanding of the aquatic carbon cycle. In this study we used a new passive sampler to measure the radiocarbon ((14)C) and stable carbon (δ(13)C) isotopic composition of dissolved CO(2) for the first time in a peatland stream throughout a complete year (May 2010-June 2011). The in-stream sampling system collected time-integrated samples of CO(2) continuously over approximately 1 month periods. The rate of CO(2) trapping was proportional to independently measured streamwater CO(2) concentrations, demonstrating that passive samplers can be used to estimate the time-averaged dissolved CO(2) concentration of streamwater. While there was little variation and no clear trend in δ(13)CO(2) values (suggesting a consistent CO(2) source), we found a clear temporal pattern in the (14)C concentration of dissolved CO(2). The (14)C age of CO(2) varied from 707±35 to 1210±39 years BP, with the youngest CO(2) in the autumn and oldest in spring/early summer. Mean stream discharge and (14)C content of dissolved CO(2) were positively correlated. We suggest that the observed pattern in the (14)C content of dissolved CO(2) reflects changes in its origin, with older carbon derived from deeper parts of the peat profile contributing proportionally more gaseous carbon during periods of low stream flow. Copyright © 2012 Elsevier B.V. All rights reserved.

Year-round Source Contributions of Fossil Fuel and Biomass Combustion to Elemental Carbon on the North Slope Alaska Utilizing Radiocarbon Analysis

NASA Astrophysics Data System (ADS)

Barrett, T. E.; Gustafsson, O.; Winiger, P.; Moffett, C.; Back, J.; Sheesley, R. J.

2015-12-01

It is well documented that the Arctic has undergone rapid warming at an alarming rate over the past century. Black carbon (BC) affects the radiative balance of the Arctic directly and indirectly through the absorption of incoming solar radiation and by providing a source of cloud and ice condensation nuclei. Among atmospheric aerosols, BC is the most efficient absorber of light in the visible spectrum. The solar absorbing efficiency of BC is amplified when it is internally mixed with sulfates. Furthermore, BC plumes that are fossil fuel dominated have been shown to be approximately 100% more efficient warming agents than biomass burning dominated plumes. The renewal of offshore oil and gas exploration in the Arctic, specifically in the Chukchi Sea, will introduce new BC sources to the region. This study focuses on the quantification of fossil fuel and biomass combustion sources to atmospheric elemental carbon (EC) during a year-long sampling campaign in the North Slope Alaska. Samples were collected at the Department of Energy Atmospheric Radiation Measurement (ARM) climate research facility in Barrow, AK, USA. Particulate matter (PM10) samples collected from July 2012 to June 2013 were analyzed for EC and sulfate concentrations combined with radiocarbon (14C) analysis of the EC fraction. Radiocarbon analysis distinguishes fossil fuel and biomass burning contributions based on large differences in end members between fossil and contemporary carbon. To perform isotope analysis on EC, it must be separated from the organic carbon fraction of the sample. Separation was achieved by trapping evolved CO2 produced during EC combustion in a cryo-trap utilizing liquid nitrogen. Radiocarbon results show an average fossil contribution of 85% to atmospheric EC, with individual samples ranging from 47% to 95%. Source apportionment results will be combined with back trajectory (BT) analysis to assess geographic source region impacts on the EC burden in the western Arctic.

Active Reconfigurable Metamaterial Unit Cell Based on Non-Foster Elements

DTIC Science & Technology

2013-10-01

Krois Ivan Bonic Aleksandar Kiricenko Damir Muha University of Zagreb Faculty of Electrical Engineering and Computing Unksa 3 Zagreb ...PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) University of Zagreb Faculty of Electrical Engineering and Computing Unksa 3 Zagreb , HR-10000 CROATIA 8...Electrical Engineering and Computing University of Zagreb Unska 3 Zagreb , HR-10000, Croatia 14 October 2013 Distribution A: Approved for

Attitudes of Students of Differenet Schools of University of Zagreb on Tooth Bleaching

PubMed Central

Diklić, Dinka; Galić, Nada; Spajić, Jelena; Prskalo, Katica

2016-01-01

Objective To compare the awareness that students from four different faculties within the University of Zagreb have of oral health and tooth bleaching procedure. Materials and Methods The study included 158 subjects (both male and female) - 38 students from the School of Dental Medicine and 40 students from each of the following faculties: the School of Medicine, the Faculty of Economics and the Faculty of Civil Engineering. The respondents were asked to fill out the survey with multiple choices by marking the answers they considered correct. Results Only 12% of the respondents followed the information on oral health. More than two thirds of all subjects brush their teeth twice a day, but there were no statistically significant differences between the subjects with respect to college or gender. More than half of the participants (55%) were satisfied, and 12% were completely satisfied with their dental appearance. About 80% of the respondents were aware of differences between teeth bleaching and teeth polishing procedures, with greater prevalence among Dental Medicine and Medicine students. 80% of all subjects would go to a dental office if they decided to whiten their teeth while less than a half (46%) of all the subjects believed that a tooth bleaching has some adverse side-effects. Conclusions There is a difference in knowledge on oral hygiene and tooth bleaching between the students from the School of Dental Medicine, the School of Medicine, the Faculty of Economics and those from the Faculty of Civil Engineering. Dental students have the best knowledge on tooth bleaching and oral health, which was in accordance with their educational guidance and level of education. PMID:28275277

Scientific Production of Research Fellows at the Zagreb University School of Medicine, Croatia

PubMed Central

Polašek, Ozren; Kolčić, Ivana; Buneta, Zoran; Čikeš, Nada; Pećina, Marko

2006-01-01

Aim To evaluate scientific production among research fellows employed at the Zagreb University School of Medicine and identify factors associated with their scientific output. Method We conducted a survey among research fellows and their mentors during June 2005. The main outcome measure was publication success, defined for each fellow as publishing at least 0.5 articles per employment year in journals indexed in the Current Contents bibliographic database. Bivariate methods and binary logistic regression were used in data analysis. Results A total of 117 fellows (response rate 95%) and 83 mentors (100%) were surveyed. The highest scientific production was recorded among research fellows employed in public health departments (median 3.0 articles, interquartile range 4.0), compared with those from pre-clinical (median 0.0, interquartile range 2.0) and clinical departments (median 1.0, interquartile range 2.0) (Kruskal-Wallis, P = 0.003). A total of 36 (29%) research fellows published at least 0.5 articles per employment year and were considered successful. Three variables were associated with fellows’ publication success: mentor’s scientific production (odds ratio [OR], 3.14; 95% confidence interval [CI], 1.31-7.53), positive mentor’s assessment (OR, 3.15; 95% CI, 1.10-9.05), and fellows’ undergraduate publication in journals indexed in the Current Contents bibliographic database (OR, 4.05; 95% CI, 1.07-15.34). Conclusion Undergraduate publication could be used as one of the main criteria in selecting research fellows. One of the crucial factors in a fellow’s scientific production and career advancement is mentor’s input, which is why research fellows would benefit most from working with scientifically productive mentors. PMID:17042070

Geochemistry, radiocarbon ages, and paleorecharge conditions along a transect in the central High Plains aquifer, southwestern Kansas, USA

USGS Publications Warehouse

McMahon, P.B.; Böhlke, J.K.; Christenson, S.C.

2004-01-01

Water samples from short-screen monitoring wells installed along a 90-km transect in southwestern Kansas were analyzed for major ions, trace elements, isotopes (H, B, C, N, O, S, Sr), and dissolved gases (He, Ne, N2, Ar, O2, CH4) to evaluate the geochemistry, radiocarbon ages, and paleorecharge conditions in the unconfined central High Plains aquifer. The primary reactions controlling water chemistry were dedolomitization, cation exchange, feldspar weathering, and O2 reduction and denitrification. Radiocarbon ages adjusted for C mass transfers ranged from <2.6 ka (14C) B.P. near the water table to 12.8 ± 0.9 ka (14C) B.P. at the base of the aquifer, indicating the unconfined central High Plains aquifer contained a stratified sequence of ground water spanning Holocene time. A cross-sectional model of steady-state ground-water flow, calibrated using radiocarbon ages, is consistent with recharge rates ranging from 0.8 mm/a in areas overlain by loess to 8 mm/a in areas overlain by dune sand. Paleorecharge temperatures ranged from an average of 15.2 ± 0.7 °C for the most recently recharged waters to 11.6 ± 0.4 °C for the oldest waters. The temperature difference between Early and Late Holocene recharge was estimated to be 2.4 ± 0.7 °C, after taking into account variable recharge elevations. Nitrogen isotope data indicate NO3 in paleorecharge (average concentration=193 μM) was derived from a relatively uniform source such as soil N, whereas NO3 in recent recharge (average concentration=885 μM) contained N from varying proportions of fertilizer, manure, and soil N. Deep water samples contained components of N2 derived from atmospheric, denitrification, and deep natural gas sources. Denitrification rates in the aquifer were slow (5 ± 2× 10−3 μmol N L−1 a−1), indicating this process would require >10 ka to reduce the average NO3 concentration in recent recharge to the Holocene background concentration.

Motivation and Career Perceptions of Dental Students at the School of Dental Medicine University of Zagreb, Croatia.

PubMed

Kobale, Mihaela; Klaić, Marija; Bavrka, Gabriela; Vodanović, Marin

2016-09-01

Health care studies are usually considered to be complex, demanding and time consuming. The right motivation toward choosing a career in the health field is of utmost importance for the successful completion of studies. The aim of this study was to gain insight into the factors motivating students at the School of Dental Medicine University of Zagreb, Croatia and, also, to examine their career perceptions. Based on specific questions from available literature, a questionnaire was designed and a total of 270 questionnaires were distributed to the first year students during 2013, 2014 and 2015. A total of 206 students responded, for a response rate of 76.3%. 26.9% of students enrolled in dental studies because it was their first career choice; 16.4% of them believed that it is easy to find a regular job in dentistry. 9.9% of students thought that salaries are high in the field of dental medicine. 45.4% of the first year students were interested in a career in private practice after graduation. These results provide interesting clues to motivation and give additional insights into the expectations of students regarding their studies and profession. The obtained data can be used for the further improvements in the quality of dental study curricula and teaching process.

THE ABSOLUTE AGE OF THE UPPER PALEOLITHIC PERIOD (SOLUTREAN, GRAVETTIAN TYPE) IN THE REGION ADJOINING THE DNESTER RIVER, DETERMINED BY RADIOCARBON DATING (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivanova, I.K.; Chernysh, A.P.

1963-01-11

Determination of the age of the dwellings of primitive man is of interest both from the point of view of the stratigraphy of quaternary deposits and for solving anthropogenetic problems. For this reason, radiocarbon dating techniques were used for layers containing paleolithic residue of Molodova V, located in a 200-m deep canyon at the right bank of the Dnester River in the Chernowith region. The measurements were carried out at a depth of 3.1 to 3.25 m from the surface. The age of layer VI was calculated at 23,000 plus or minus 800 years which is close to the agemore » reported for the Czechoslovak gravette and from samples from the French Abri plateau. Thus, radiocarbon dating results confirmed earlier findings obtained by topological means concerning the age of the region near the Dnester River. (TTT)« less

Vibracore, Radiocarbon, Microfossil, and Grain-Size Data from Apalachicola Bay, Florida

USGS Publications Warehouse

Twichell, D.C.; Pendleton, E.A.; Poore, R.Z.; Osterman, L.E.; Kelso, K.W.

2009-01-01

In 2007, the U.S. Geological Survey collected 24 vibracores within Apalachicola Bay, Florida. The vibracores were collected by using a Rossfelder electric percussive (P-3) vibracore system during a cruise on the Research Vessel (R/V) G.K. Gilbert. Selection of the core sites was based on a geophysical survey that was conducted during 2005 and 2006 in collaboration with the National Oceanic and Atmospheric Administration's (NOAA) Coastal Services Center (CSC) and the Apalachicola Bay National Estuarine Research Reserve. This report contains the vibracore data logs, photographs, and core-derived data including grain-size analyses, radiocarbon ages, microfossil counts, and sedimentological interpretations. The long-term goal of this study is to provide maps, data, and assistance to the Apalachicola Bay National Estuarine Research Reserve in their effort to monitor and understand the geology and ecology of Apalachicola Bay Estuary. These data will inform coastal managers charged with the responsibility for resource preservation.

A six decades long follow-up on body size in adolescents from Zagreb, Croatia (1951-2010).

PubMed

Zajc Petranović, Matea; Tomas, Željka; Smolej Narančić, Nina; Škarić-Jurić, Tatjana; Veček, Andrea; Miličić, Jasna

2014-03-01

Most studies analysing the influence of socioeconomic deterioration on body size focus on the impact of food shortages and diseases on the growth in early childhood. To evaluate how socioeconomic conditions influence the growth during the adolescence, we tracked the body size of 15-19 year-olds over the last sixty years covering the socialist period (1951-1990), the war (1991-1995) and the transition to capitalistic economy. This study of Zagreb, Croatia, adolescent population provides information on the secular trend in height, weight and Body Mass Index (BMI) and examines their relation with Real Gross Domestic Product. From 1951 to 2010 the girls' height approximately increased by 6.2cm and weight by 6.8kg, while the boys' height increased by 12.2cm and weight by 17.3kg. Prior to 1991 mean BMI in girls was higher than in boys, but from 1991 on, the interrelation between the sexes has been opposite, possibly mirroring the cultural trends that started in mid-1970s and reflecting higher sensitivity of boys to the socioeconomic changes. In conclusion, the secular trend in body size over the investigated period reflects the positive economic trends interrupted by the war. The recent increase in BMI corresponds to the country's economic recovery and indicates the "nutrition transition". Copyright © 2013 Elsevier B.V. All rights reserved.

Characteristics of self-medication for pain relief among first-year health care students in Zagreb, Croatia.

PubMed

Brlić, Kristina Čuljak; Janev Holcer, Nataša; Sović, Slavica; Štimac, Danijela

2014-12-01

Taking over the responsibility for one's own health and active participation in eliminating the existing health problems is ever more widespread in the world. Self-medication in the form of using any kind of therapy without previous consultation with medical professionals has been ever more common among student populations in many countries. The aim of this study was to determine the attitudes about self-medication for pain relief and features of self-medication in first-year students of the University of Applied Health Studies in Zagreb. The study was conducted using an anonymous questionnaire, which was completed by 389 respondents. Taking painkillers in the past year was reported by 74.6% of respondents, significantly more by female students (80.8%); 62.6% of female students used painkillers once a month versus 45.7% of male students taking analgesics once a year. Ibuprofen was preferred by female students and acetylsalicylic acid by male students. Headache was the most common indication for taking painkillers (76.6%), followed by menstrual discomforts in female students (66.2%) and toothache (28.6%). Significant sex differences were recorded in the choice of drugs, indications for self-medication, and frequency of drug use. There were no differences between study courses. Appropriate student education and improved information transfer between professionals and students are the key elements to ensure judicious, quality and knowledge based use of drugs among students.

Attitude towards Oral Health at Various Colleges of the University of Zagreb: A Pilot Study.

PubMed

Ivica, Anja; Galić, Nada

2014-06-01

The aim of this study was to compare the oral status of three various groups of students: students of the School of Dental Medicine, students of technical sciences and students of humanities. Research included 58 students of the University of Zagreb. They answered 3 questions: how often they brush their teeth, how often they visit their dentist and how important dental health is to them. After a standard dental check-up we calculated the DMFT index. They were given an indicator for plaque Mira-2-Ton® (Hager Werken, Duisburg, Germany) and we calculated the plaque index. For statistical analysis the ANOVA test was used. Students of the School of Dental Medicine had a lower plaque index than other students and this was statistically significant (p=0.0018; f=7.14). They also had a lower DMFT index, but it was not statistically significant (p=0.1004; f=2.4). 83% of students said that they brushed their teeth 2-3 times a day. Only 17% of all students brush their teeth more than 3 times a day and they are all students of the School of Dental Medicine (21% of them). Perception of oral health is on a high level, but perception of oral disease is not. The social approval of the answer was also an important factor. Students of the School of Dental Medicine are an illustrative example of improving our habits due to education.

Nutritional Issues and Nutrition Support in Older Home Care Patients in the City of Zagreb.

PubMed

Vranešić Bender, Darija; Kovačević, Marta; Hanževački, Miro; Vrabec, Božena; Benković, Vanesa; Domislović, Viktor; Krznarić, Željko

2017-12-01

Population aging is a global demographic trend showing continuous growth and among its consequences is a rise in malnutrition that is characteristic for the elderly. The objective of this study was to evaluate nutritional status of elderly home care patients immediately after hospital discharge and to determine factors that affect nutritional status using questionnaires based on validated tools (NRS-2002, DETERMINE checklist) and basic medical history data. The study involved 76 elderly individuals (51.3% of them older than 70) living in the City of Zagreb. The nutritional status assessment using the NRS-2002 tool showed that 57.6% of the subjects were at nutritional risk. The findings of the assessment by use of the DETERMINE tool were also unfavorable, indicating that 82.1% of persons older than 70 were categorized as being at a high nutritional risk, while 17.9% were at moderate risk. The DETERMINE checklist elements (illness; reduced intake of fruits, vegetables or dairy products; alcohol consumption; oral health problems; and weight loss) were linked to a higher NRS score. The mean number of hospital days in subjects at nutritional risk was 14.27 (the mean number in the Republic of Croatia is 8.56 days). Although the study involved a small number of subjects, the results showed a substantial presence of malnutrition among the elderly. A timely -intervention by the healthcare system and training of healthcare personnel can be a step towards achieving a better nutritional status.

Attitude towards Oral Health at Various Colleges of the University of Zagreb: A Pilot Study

PubMed Central

Ivica, Anja; Galić, Nada

2014-01-01

Purpose The aim of this study was to compare the oral status of three various groups of students: students of the School of Dental Medicine, students of technical sciences and students of humanities. Material and methods Research included 58 students of the University of Zagreb. They answered 3 questions: how often they brush their teeth, how often they visit their dentist and how important dental health is to them. After a standard dental check-up we calculated the DMFT index. They were given an indicator for plaque Mira-2-Ton® (Hager Werken, Duisburg, Germany) and we calculated the plaque index. For statistical analysis the ANOVA test was used. Results Students of the School of Dental Medicine had a lower plaque index than other students and this was statistically significant (p=0.0018; f=7.14). They also had a lower DMFT index, but it was not statistically significant (p=0.1004; f=2.4). 83% of students said that they brushed their teeth 2-3 times a day. Only 17% of all students brush their teeth more than 3 times a day and they are all students of the School of Dental Medicine (21% of them). Perception of oral health is on a high level, but perception of oral disease is not. The social approval of the answer was also an important factor. Conclusion Students of the School of Dental Medicine are an illustrative example of improving our habits due to education. PMID:27688358

Radiocarbon Releases from the 2011 Fukushima Nuclear Accident

PubMed Central

Xu, Sheng; Cook, Gordon T.; Cresswell, Alan J.; Dunbar, Elaine; Freeman, Stewart P. H. T.; Hou, Xiaolin; Jacobsson, Piotr; Kinch, Helen R.; Naysmith, Philip; Sanderson, David C. W.; Tripney, Brian G.

2016-01-01

Radiocarbon activities were measured in annual tree rings for the years 2009 to 2015 from Japanese cedar trees (Cryptomeria japonica) collected at six sites ranging from 2.5–38 km northwest and north of the Fukushima Dai-ichi nuclear power plant. The 14C specific activity varied from 280.4 Bq kg−1 C in 2010 to 226.0 Bq kg−1 C in 2015. The elevated 14C activities in the 2009 and 2010 rings confirmed 14C discharges during routine reactor operations, whereas those activities that were indistinguishable from background in 2012–2015 coincided with the permanent shutdown of the reactors after the accident in 2011. High-resolution 14C analysis of the 2011 ring indicated 14C releases during the Fukushima accident. The resulted 14C activity decreased with increasing distance from the plant. The maximum 14C activity released during the period of the accident was measured 42.4 Bq kg−1 C above the natural ambient 14C background. Our findings indicate that, unlike other Fukushima-derived radionuclides, the 14C released during the accident is indistinguishable from ambient background beyond the local environment (~30 km from the plant). Furthermore, the resulting dose to the local population from the excess 14C activities is negligible compared to the dose from natural/nuclear weapons sources. PMID:27841312

Radiocarbon Releases from the 2011 Fukushima Nuclear Accident

NASA Astrophysics Data System (ADS)

Xu, Sheng; Cook, Gordon T.; Cresswell, Alan J.; Dunbar, Elaine; Freeman, Stewart P. H. T.; Hou, Xiaolin; Jacobsson, Piotr; Kinch, Helen R.; Naysmith, Philip; Sanderson, David C. W.; Tripney, Brian G.

2016-11-01

Radiocarbon activities were measured in annual tree rings for the years 2009 to 2015 from Japanese cedar trees (Cryptomeria japonica) collected at six sites ranging from 2.5-38 km northwest and north of the Fukushima Dai-ichi nuclear power plant. The 14C specific activity varied from 280.4 Bq kg-1 C in 2010 to 226.0 Bq kg-1 C in 2015. The elevated 14C activities in the 2009 and 2010 rings confirmed 14C discharges during routine reactor operations, whereas those activities that were indistinguishable from background in 2012-2015 coincided with the permanent shutdown of the reactors after the accident in 2011. High-resolution 14C analysis of the 2011 ring indicated 14C releases during the Fukushima accident. The resulted 14C activity decreased with increasing distance from the plant. The maximum 14C activity released during the period of the accident was measured 42.4 Bq kg-1 C above the natural ambient 14C background. Our findings indicate that, unlike other Fukushima-derived radionuclides, the 14C released during the accident is indistinguishable from ambient background beyond the local environment (~30 km from the plant). Furthermore, the resulting dose to the local population from the excess 14C activities is negligible compared to the dose from natural/nuclear weapons sources.

Radiocarbon Records of Fossil Fuel Emissions From Urban Trees in the Greater Salt Lake Valley From Mid-Century to Present.

NASA Astrophysics Data System (ADS)

Chritz, K.; Buchert, M.; Walker, J. C.; Mendoza, D.; Pataki, D. E.; Xu, X.; Lin, J. C.

2017-12-01

Generating long term records of fossil fuel emissions of urban environments is complicated by the fact that direct observations of emissions and urban atmospheric CO2 concentrations were only collected in the recent past. Radiocarbon (14C) in tree rings from urban trees can provide archives of fossil fuel emissions that may track population growth over time, as higher population density is typically correlated with increased vehicular traffic and associated CO2 emissions, which are radiocarbon dead. We present radiocarbon measurements (n=125) from five roadside green ash trees (Fraxinus pennsylvanica) located in three cities of northern Utah - Salt Lake City (urban, 2016 population: 193,744), Logan City (agricultural, 2016 population: 49,110) and Heber (rural, 2016 population: 14,969). Urban trees were cored in four cardinal directions and ring widths were measured and counted to establish a chronology. One ring from every third year in a single core from each tree was removed and holocellulose was extracted from bulk wood of individual rings for 14C analysis. Fraction CO2 from fossil fuel burning (CO2-ff) was calculated using a simple mass-balance calculation from measured 14C values and remote background atmospheric 14CO2 values for NH Zone 2. The data from all three cities indicate a general trend of increasing CO2-ff uptake by the trees from 1980s to present, as expected with increased population growth and vehicular traffic. However, records in all three cities show unique elevated CO2-ff prior to the 1980s, assuming similar climate patterns through time, diverging from historic population size. We employed atmospheric simulations from the STILT (Stochastic Time-Inverted Lagrangian Transport) models for each of these trees to create footprints to determine source areas for CO2. These footprints reveal that atmospheric sampling areas can be large for certain trees, and other sources of 14C dead carbon, such as coal and natural gas from industrial emissions

Re-Emergence of Excess Bomb Radiocarbon in Upwelling Waters with High-Latitude Origins

NASA Astrophysics Data System (ADS)

Lindsay, C. M.; Lehman, S.

2016-02-01

The quantity of radiocarbon (14C) in the atmosphere was nearly doubled by nuclear weapons testing in the 1960s. Since then, the terrestrial biosphere and the ocean have absorbed most of the excess 14C from the atmosphere, although atmospheric radiocarbon activity (∆14C) continues to decline due to ongoing emissions of 14C-free CO2 from combustion of fossil fuels. The large transient decline in atmospheric ∆14C combined with gas exchange at the surface and spatially variable time scales of ocean mixing have led to large ∆14C gradients in the surface ocean between upwelling- and downwelling-dominated regions. These gradients continue to evolve over time. We examine the rate of change of surface ocean ∆14C between CLIVAR (2000-2011) and WOCE era (1990s) or other slightly earlier (1980s) datasets and find spatial patterns that reveal mixing between 14C-enriched mode waters, 14C-depleted deep waters and surface waters that are well-equilibrated with the atmosphere. The ∆14C of mode water reaching equatorial upwelling regions has increased between the WOCE and CLIVAR time periods, and the greater contribution of 14C to the low-latitude surface ocean appears to have significantly offset the ∆14C decline otherwise imparted by air-sea gas exchange with the atmosphere. Consequently, ∆14C gradients between low-latitude upwelling regions and gyre centers have weakened proportionally more than between gyre centers and regions where pre-industrial water still upwells, such as the Southern Ocean. Properly accounting for the re-emergence of water with post-industrial characteristics is important to constrain earth system models that seek to explain DIC, pH and other anthropogenically perturbed tracers in the surface ocean. Because of the history of ∆14C in the atmosphere, ocean ∆14C is a useful tracer for this purpose.

High-precision radiocarbon dating of political collapse and dynastic origins at the Maya site of Ceibal, Guatemala

PubMed Central

Inomata, Takeshi; Triadan, Daniela; MacLellan, Jessica; Burham, Melissa; Aoyama, Kazuo; Palomo, Juan Manuel; Yonenobu, Hitoshi; Pinzón, Flory; Nasu, Hiroo

2017-01-01

The lowland Maya site of Ceibal, Guatemala, had a long history of occupation, spanning from the Middle Preclassic Period through the Terminal Classic (1000 BC to AD 950). The Ceibal-Petexbatun Archaeological Project has been conducting archaeological investigations at this site since 2005 and has obtained 154 radiocarbon dates, which represent the largest collection of radiocarbon assays from a single Maya site. The Bayesian analysis of these dates, combined with a detailed study of ceramics, allowed us to develop a high-precision chronology for Ceibal. Through this chronology, we traced the trajectories of the Preclassic collapse around AD 150–300 and the Classic collapse around AD 800–950, revealing similar patterns in the two cases. Social instability started with the intensification of warfare around 75 BC and AD 735, respectively, followed by the fall of multiple centers across the Maya lowlands around AD 150 and 810. The population of Ceibal persisted for some time in both cases, but the center eventually experienced major decline around AD 300 and 900. Despite these similarities in their diachronic trajectories, the outcomes of these collapses were different, with the former associated with the development of dynasties centered on divine rulership and the latter leading to their downfalls. The Ceibal dynasty emerged during the period of low population after the Preclassic collapse, suggesting that this dynasty was placed under the influence from, or by the direct intervention of, an external power. PMID:28115691

High-precision radiocarbon dating of political collapse and dynastic origins at the Maya site of Ceibal, Guatemala.

PubMed

Inomata, Takeshi; Triadan, Daniela; MacLellan, Jessica; Burham, Melissa; Aoyama, Kazuo; Palomo, Juan Manuel; Yonenobu, Hitoshi; Pinzón, Flory; Nasu, Hiroo

2017-02-07

The lowland Maya site of Ceibal, Guatemala, had a long history of occupation, spanning from the Middle Preclassic Period through the Terminal Classic (1000 BC to AD 950). The Ceibal-Petexbatun Archaeological Project has been conducting archaeological investigations at this site since 2005 and has obtained 154 radiocarbon dates, which represent the largest collection of radiocarbon assays from a single Maya site. The Bayesian analysis of these dates, combined with a detailed study of ceramics, allowed us to develop a high-precision chronology for Ceibal. Through this chronology, we traced the trajectories of the Preclassic collapse around AD 150-300 and the Classic collapse around AD 800-950, revealing similar patterns in the two cases. Social instability started with the intensification of warfare around 75 BC and AD 735, respectively, followed by the fall of multiple centers across the Maya lowlands around AD 150 and 810. The population of Ceibal persisted for some time in both cases, but the center eventually experienced major decline around AD 300 and 900. Despite these similarities in their diachronic trajectories, the outcomes of these collapses were different, with the former associated with the development of dynasties centered on divine rulership and the latter leading to their downfalls. The Ceibal dynasty emerged during the period of low population after the Preclassic collapse, suggesting that this dynasty was placed under the influence from, or by the direct intervention of, an external power.

Using 50 years of soil radiocarbon data to identify optimal approaches for estimating soil carbon residence times

NASA Astrophysics Data System (ADS)

Baisden, W. T.; Canessa, S.

2013-01-01

In 1959, Athol Rafter began a substantial programme of systematically monitoring the flow of 14C produced by atmospheric thermonuclear tests through organic matter in New Zealand soils under stable land use. A database of ∼500 soil radiocarbon measurements spanning 50 years has now been compiled, and is used here to identify optimal approaches for soil C-cycle studies. Our results confirm the potential of 14C to determine residence times, by estimating the amount of ‘bomb 14C’ incorporated. High-resolution time series confirm this approach is appropriate, and emphasise that residence times can be calculated routinely with two or more time points as little as 10 years apart. This approach is generally robust to the key assumptions that can create large errors when single time-point 14C measurements are modelled. The three most critical assumptions relate to: (1) the distribution of turnover times, and particularly the proportion of old C (‘passive fraction’), (2) the lag time between photosynthesis and C entering the modelled pool, (3) changes in the rates of C input. When carrying out approaches using robust assumptions on time-series samples, multiple soil layers can be aggregated using a mixing equation. Where good archived samples are available, AMS measurements can develop useful understanding for calibrating models of the soil C cycle at regional to continental scales with sample numbers on the order of hundreds rather than thousands. Sample preparation laboratories and AMS facilities can play an important role in coordinating the efficient delivery of robust calculated residence times for soil carbon.

A simple radiocarbon dating method for determining the age and growth rate of deep-sea sponges

NASA Astrophysics Data System (ADS)

Fallon, S. J.; James, K.; Norman, R.; Kelly, M.; Ellwood, M. J.

2010-04-01

The ability to reliably age siliceous sponges is explored using radiocarbon dating of several hexactinellid sponge specimens including Rossella racovitzaeracovitzae Topsent, 1901 ( C. Hexactinellida: O. Lyssacinosida: F. Rossellidae), collected from the Ross Sea, Antarctica. The optimal pretreatment was found to consist of both sequential acid digestion and pre-roasting at temperatures >400 °C. Subsequent combustion at 900 °C liberated the proteinaceous material within the spicule matrix and once the reservoir age of the surrounding water was accounted for, a linear extension rate was calculated to be around 2.9 mm yr -1, aging the sponge at ˜440 years old.

Improved radiocarbon dating for contaminated archaeological bone collagen, silk, wool and hair samples via cross-flow nanofiltrated amino acids.

PubMed

Boudin, Mathieu; Boeckx, Pascal; Vandenabeele, Peter; Van Strydonck, Mark

2013-09-30

Radiocarbon dating and stable isotope analyses of bone collagen, wool, hair and silk contaminated with extraneous carbon (e.g. humic substances) does not yield reliable results if these materials are pre-treated using conventional methods. A cross-flow nanofiltration method was developed that can be applied to various protein materials like collagen, hair, silk, wool and leather, and should be able to remove low-molecular and high-molecular weight contaminants. To avoid extraneous carbon contamination via the filter a ceramic filter (molecular weight cut-off of 200 Da) was used. The amino acids, released by hot acid hydrolysis of the protein material, were collected in the permeate and contaminants in the retentate (>200 Da). (14)C-dating results for various contaminated archaeological samples were compared for bulk material (pre-treated with the conventional methods) and for cross-flow nanofiltrated amino acids (permeate) originating from the same samples. Contamination and quality control of (14)C dates of bulk and permeate samples were obtained by measuring C:N ratios, fluorescence spectra, and δ(13)C and δ(15)N values of the samples. Cross-flow nanofiltration decreases the C:N ratio which means that contaminants have been removed. Cross-flow nanofiltration clearly improved sample quality and (14)C results. It is a quick and non-labor-intensive technique and can easily be implemented in any (14)C and stable isotope laboratory for routine sample pre-treatment analyses. Copyright © 2013 John Wiley & Sons, Ltd.

[Bacteremia and sepsis in patients hospitalized at the Dr. Fran Mihaljevíc Clinic for Infectious Diseases in Zagreb 1987-1991].

PubMed

Skerk, V; Schönwald, S; Bobinac, E; Bejuk, D; Zrinsćak, J

1995-01-01

A total number of 836 episodes of bacteremia and fungemia were examined in 823 hospitalized patients in the University Hospital of Infectious Diseases "Dr Fran Mihaljević" Zagreb from the beginning of 1987 to the end of 1991. Twenty-five percent of them were nosocomial bacteremias and 5% were polymicrobial bacteremias. The most frequently isolated causative agents were Salmonella spp. (26%), Escherichia coli (17%), Streptococcus pneumoniae (11%) and Staphylococcus aureus (8%). There were 34% of gram-positive bacteremias. The increased frequency of nosocomial bacteremias caused by coagulase-negative staphylococci was recorded. The frequency of coagulase-negative staphylococci strains resistant to gentamicin and Klebsiella spp. strains resistant to cefotaxime was increased. Shock was present in 19% of episodes. Relation between septic shock occurrence and causative agent of bacteremia was not proved. Mortality in patients with bacteremia was 13%, and total mortality was 20%. The outcome of the disease was in direct relation with causative agent of bacteremia. The initial empiric antimicrobial therapy was prolonged in 91% of episodes of bacteremia after blood culture results were known.

Radiocarbon-depleted CO2 evidence for fuel biodegradation at the Naval Air Station North Island (USA) fuel farm site.

PubMed

Boyd, Thomas J; Pound, Michael J; Lohr, Daniel; Coffin, Richard B

2013-05-01

Dissolved CO(2) radiocarbon and stable carbon isotope ratios were measured in groundwater from a fuel contaminated site at the North Island Naval Air Station in San Diego, CA (USA). A background groundwater sampling well and 16 wells in the underground fuel contamination zone were evaluated. For each sample, a two end-member isotopic mixing model was used to determine the fraction of CO(2) derived from fossil fuel. The CO(2) fraction from fossil sources ranged from 8 to 93% at the fuel contaminated site, while stable carbon isotope values ranged from -14 to +5‰VPDB. Wells associated with highest historical and contemporary fuel contamination showed the highest fraction of CO(2) derived from petroleum (fossil) sources. Stable carbon isotope ratios indicated sub-regions on-site with recycled CO(2) (δ(13)CO(2) as high as +5‰VPDB) - most likely resulting from methanogenesis. Ancillary measurements (pH and cations) were used to determine that no fossil CaCO(3), for instance limestone, biased the analytical conclusions. Radiocarbon analysis is verified as a viable and definitive technique for confirming fossil hydrocarbon conversion to CO(2) (complete oxidation) at hydrocarbon-contaminated groundwater sites. The technique should also be very useful for assessing the efficacy of engineered remediation efforts and by using CO(2) production rates, contaminant mass conversion over time and per unit volume.

Earliest Human Presence in North America Dated to the Last Glacial Maximum: New Radiocarbon Dates from Bluefish Caves, Canada.

PubMed

Bourgeon, Lauriane; Burke, Ariane; Higham, Thomas

2017-01-01

The timing of the first entry of humans into North America is still hotly debated within the scientific community. Excavations conducted at Bluefish Caves (Yukon Territory) from 1977 to 1987 yielded a series of radiocarbon dates that led archaeologists to propose that the initial dispersal of human groups into Eastern Beringia (Alaska and the Yukon Territory) occurred during the Last Glacial Maximum (LGM). This hypothesis proved highly controversial in the absence of other sites of similar age and concerns about the stratigraphy and anthropogenic signature of the bone assemblages that yielded the dates. The weight of the available archaeological evidence suggests that the first peopling of North America occurred ca. 14,000 cal BP (calibrated years Before Present), i.e., well after the LGM. Here, we report new AMS radiocarbon dates obtained on cut-marked bone samples identified during a comprehensive taphonomic analysis of the Bluefish Caves fauna. Our results demonstrate that humans occupied the site as early as 24,000 cal BP (19,650 ± 130 14C BP). In addition to proving that Bluefish Caves is the oldest known archaeological site in North America, the results offer archaeological support for the "Beringian standstill hypothesis", which proposes that a genetically isolated human population persisted in Beringia during the LGM and dispersed from there to North and South America during the post-LGM period.

Earliest Human Presence in North America Dated to the Last Glacial Maximum: New Radiocarbon Dates from Bluefish Caves, Canada

PubMed Central

Bourgeon, Lauriane; Burke, Ariane; Higham, Thomas

2017-01-01

The timing of the first entry of humans into North America is still hotly debated within the scientific community. Excavations conducted at Bluefish Caves (Yukon Territory) from 1977 to 1987 yielded a series of radiocarbon dates that led archaeologists to propose that the initial dispersal of human groups into Eastern Beringia (Alaska and the Yukon Territory) occurred during the Last Glacial Maximum (LGM). This hypothesis proved highly controversial in the absence of other sites of similar age and concerns about the stratigraphy and anthropogenic signature of the bone assemblages that yielded the dates. The weight of the available archaeological evidence suggests that the first peopling of North America occurred ca. 14,000 cal BP (calibrated years Before Present), i.e., well after the LGM. Here, we report new AMS radiocarbon dates obtained on cut-marked bone samples identified during a comprehensive taphonomic analysis of the Bluefish Caves fauna. Our results demonstrate that humans occupied the site as early as 24,000 cal BP (19,650 ± 130 14C BP). In addition to proving that Bluefish Caves is the oldest known archaeological site in North America, the results offer archaeological support for the “Beringian standstill hypothesis”, which proposes that a genetically isolated human population persisted in Beringia during the LGM and dispersed from there to North and South America during the post-LGM period. PMID:28060931

Report of the Third Heart Surgery Forum Scientific Sessions: Zagreb, Croatia December 6-8, 2017: Conference Highlights.

PubMed

Firstenberg, Michael S; Nguyen, Tom C; Roberts, Harold; Levinson, Mark M; Rudez, Igo

2018-02-26

The Heart Surgery Forum is an online community dedicated to topics related to all aspects of cardiothoracic surgery. It consists of an informative website (www.hsforum.com), a traditional indexed journal both in print and online, and an email-based "list-serv" for discussion of surgical cases and techniques. The email list-serv, "OpenHeart-L" (The Forum) is composed of surgeons and allied specialties (perfusion, anesthesia, nursing). Dr. Mark Levinson (USA) started The Forum originally in 1995. He also served as the first Editor-in-Chief of the print journal for many years. Coinciding with the popularity of The Forum, and the desire by many members to meet in person, the First Heart Surgery Forum Conference (#1 HSF) was held in Savudrija, Istria, Croatia in 2010. The overwhelming success of this meeting, in terms of attendance and scientific content, resulted in #2 HSF being held in Split, Croatia in 2014. Recently, the #3 HSF meeting was held in Zagreb, Croatia on December 6-8th, 2017. This report highlights the scientific events of this meeting, and more importantly aims to inspire greater involvement by the international cardiothoracic community. Substantial increasing attendance was seen at each subsequent meeting, not only in terms of the number of participants and lectures, but also in the number of countries represented.

Motivation and Career Perceptions of Dental Students at the School of Dental Medicine University of Zagreb, Croatia

PubMed Central

Kobale, Mihaela; Klaić, Marija; Bavrka, Gabriela

2016-01-01

Purpose Health care studies are usually considered to be complex, demanding and time consuming. The right motivation toward choosing a career in the health field is of utmost importance for the successful completion of studies. The aim of this study was to gain insight into the factors motivating students at the School of Dental Medicine University of Zagreb, Croatia and, also, to examine their career perceptions. Material and Methods Based on specific questions from available literature, a questionnaire was designed and a total of 270 questionnaires were distributed to the first year students during 2013, 2014 and 2015. Results A total of 206 students responded, for a response rate of 76.3%. 26.9% of students enrolled in dental studies because it was their first career choice; 16.4% of them believed that it is easy to find a regular job in dentistry. 9.9% of students thought that salaries are high in the field of dental medicine. 45.4% of the first year students were interested in a career in private practice after graduation. These results provide interesting clues to motivation and give additional insights into the expectations of students regarding their studies and profession. Conclussion The obtained data can be used for the further improvements in the quality of dental study curricula and teaching process. PMID:27847393

Radiocarbon dating of dissolved inorganic carbon in groundwater from confined parts of the Upper Floridan aquifer, Florida, USA

USGS Publications Warehouse

Plummer, Niel; Sprinkle, C.L.

2001-01-01

Geochemical reaction models were evaluated to improve radiocarbon dating of dissolved inorganic carbon (DIC) in groundwater from confined parts of the Upper Floridan aquifer in central and northeastern Florida, USA. The predominant geochemical reactions affecting the 14C activity of DIC include (1) dissolution of dolomite and anhydrite with calcite precipitation (dedolomitization), (2) sulfate reduction accompanying microbial degradation of organic carbon, (3) recrystallization of calcite (isotopic exchange), and (4) mixing of fresh water with as much as 7% saline water in some coastal areas. The calculated cumulative net mineral transfers are negligibly small in upgradient parts of the aquifer and increase significantly in downgradient parts of the aquifer, reflecting, at least in part, upward leakage from the Lower Floridan aquifer and circulation that contacted middle confining units in the Floridan aquifer system. The adjusted radiocarbon ages are independent of flow path and represent travel times of water from the recharge area to the sample point in the aquifer. Downgradient from Polk City (adjusted age 1.7 ka) and Keystone Heights (adjusted age 0.4 ka), 14 of the 22 waters have adjusted 14C ages of 20-30 ka, indicating that most of the fresh-water resource in the Upper Floridan aquifer today was recharged during the last glacial period. All of the paleowaters are enriched in 18O and 2H relative to modern infiltration, with maximum enrichment in ??18O of approximately 2.0%o.

Radiocarbon dates for lava flows and pyroclastic deposits on Sao Miguel, Azores

USGS Publications Warehouse

Moore, R.B.; Rubin, M.

1991-01-01

We report 63 new radiocarbon analyses of samples from Sao Miguel, the largest island in the Azores archipelago. The samples are mainly carbonized tree roots and other plant material collected from beneath 20 mafic lava flows and spatter deposits and from within and beneath 42 trachytic pyroclastic flow, pyroclastic surge, mudflow, pumice-fall and lacustrine deposits and lava flows. One calcite date is reported. These dates establish ages for 48 previously undated lava flows and pyroclastic deposits, and revise three ages previously reported. These data are critical to deciphering the Holocene and late Pleistocene eruptive history of Sao Miguel and evaluating its potential volcanic hazards. Average dormant intervals during the past 3000 years are about 400 years for Sete Cidades volcano, 145 years for volcanic Zone 2, 1150 years for Agua de Pau volcano and 320 years for Furnas volcano. No known eruptions have occurred in volcanic Zone 4 during the past 3000 years. -from Authors

(Congressional Interest) Institute for Science, Space and Security (ISSS)

DTIC Science & Technology

2012-03-19

Studies program between UCCS and University of Zagreb , Croatia (City of Zagreb funding). Conducted three days of meetings with City/University of Zagreb ...security and assist the University of Zagreb in establishing a regional (Eastern Europe) Center of Excellence in Homeland Security. In the long-term...UCCS will assist the University of Zagreb in maturing the Center of Excellence and designing, developing and delivering masters and doctoral degrees

(Congressional Interest) Network Information and Space Security Center

DTIC Science & Technology

2011-09-30

Zagreb , Croatia (City of Zagreb funding). Conducted three days of meetings with City/University of Zagreb , Croatia officials to structure terms for a...partnership with UCCS. In the short-term, UCCS will develop and deliver several courses in homeland security and assist the University of Zagreb in... Zagreb in maturing the Center of Excellence and designing, developing and delivering masters and doctoral degrees in homeland security. Hosted a group of

Analysis of monthly, winter, and annual temperatures in Zagreb, Croatia, from 1864 to 2010: the 7.7-year cycle and the North Atlantic Oscillation

NASA Astrophysics Data System (ADS)

Sen, Asok K.; Ogrin, Darko

2016-02-01

Long instrumental records of meteorological variables such as temperature and precipitation are very useful for studying regional climate in the past, present, and future. They can also be useful for understanding the influence of large-scale atmospheric circulation processes on the regional climate. This paper investigates the monthly, winter, and annual temperature time series obtained from the instrumental records in Zagreb, Croatia, for the period 1864-2010. Using wavelet analysis, the dominant modes of variability in these temperature series are identified, and the time intervals over which these modes may persist are delineated. The results reveal that all three temperature records exhibit low-frequency variability with a dominant periodicity at around 7.7 years. The 7.7-year cycle has also been observed in the temperature data recorded at several other stations in Europe, especially in Northern and Western Europe, and may be linked to the North Atlantic Oscillation (NAO) and/or solar/geomagnetic activity.

Tracking of BMI, fatness and cardiorespiratory fitness from adolescence to middle adulthood: the Zagreb Growth and Development Longitudinal Study.

PubMed

Sorić, Maroje; Jembrek Gostović, Mirjana; Gostović, Mladen; Hočevar, Marija; Mišigoj-Duraković, Marjeta

2014-01-01

Effective intervention strategies aiming to improve cardiorespiratory fitness and to decrease body fatness are needed. However, long-term stability of these traits is not well understood. To assess long-term tracking of cardiorespiratory fitness and body fatness from late adolescence to middle adulthood. The sample consisted of 50 participants (31 boys) from the Zagreb Growth and Development Longitudinal Study who were followed up in adulthood (median age = 43). Fatness was evaluated through BMI and skin-folds, while cardiorespiratory fitness was assessed using a cardiopulmonary exercise test. Inter-age partial correlation coefficients were calculated to evaluate tracking. Body mass index and skin-folds showed moderate tracking from age 15 years to middle adulthood (partial r = 0.55, p < 0.001 and partial r = 0.52, p < 0.001, respectively), while tracking of subcutaneous fat distribution was somewhat lower (partial r = 0.38, p < 0.01). At the same time, the observed tracking of peak oxygen uptake was low-to-moderate (partial r = 0.30, p = 0.03), while ventilatory aerobic and anaerobic thresholds did not show significant tracking. The results of this study indicate that preventive efforts aiming to increase cardiorespiratory fitness should include all adolescents, irrespective of their cardiorespiratory fitness status. Conversely, strategies aiming at obesity prevention should focus on high-risk groups of adolescents.

Radiocarbon dating, chronologic framework, and changes in accumulation rates of holocene estuarine sediments from Chesapeake Bay

USGS Publications Warehouse

Colman, Steven M.; Baucom, P.C.; Bratton, J.F.; Cronin, T. M.; McGeehin, J.P.; Willard, D.; Zimmerman, A.R.; Vogt, P.R.

2002-01-01

Rapidly accumulating Holocene sediments in estuaries commonly are difficult to sample and date. In Chesapeake Bay, we obtained sediment cores as much as 20 m in length and used numerous radiocarbon ages measured by accelarator mass spectrometry methods to provide the first detailed chronologies of Holocene sediment accumulation in the bay. Carbon in these sediments is a complex mixture of materials from a variety of sources. Analyses of different components of the sediments show that total organic carbon ages are largely unreliable, because much of the carbon (including coal) has been transported to the bay from upstream sources and is older than sediments in which it was deposited. Mollusk shells (clams, oysters) and foraminifera appear to give reliable results, although reworking and burrowing are potential problems. Analyses of museum specimens collected alive before atmospheric nuclear testing suggest that the standard reservoir correction for marine samples is appropriate for middle to lower Chesapeake Bay. The biogenic carbonate radiocarbon ages are compatible with 210 Pb and 137 Cs data and pollen stratigraphy from the same sites. Post-settlement changes in sediment transport and accumulation is an important environmental issue in many estuaries, including the Chesapeake. Our data show that large variations in sediment mass accumulation rates occur among sites. At shallow water sites, local factors seem to control changes in accumulation rates with time. Our two relatively deep-water sites in the axial channel of the bay have different long-term average accumulation rates, but the history of sediment accumulation at these sites appears to reflect overall conditions in the bay. Mass accumulation rates at the two deep-water sites rapidly increased by about fourfold coincident with widespread land clearance for agriculture in the Chesapeake watershed.

Radiocarbon Dates from Volcanic Deposits of the Chaos Crags and Cinder Cone Eruptive Sequences and Other Deposits, Lassen Volcanic National Park and Vicinity, California

USGS Publications Warehouse

Clynne, Michael A.; Christiansen, Robert L.; Trimble, Deborah A.; McGeehin, John P.

2008-01-01

This contribution reports radiocarbon ages obtained from charcoal, wood and other samples collected between 1979 and 2001 in Lassen Volcanic National Park and vicinity and a few samples from other nearby localities. Most of the samples are from the Chaos Crags and Cinder Cone eruptive sequences. Brief summaries are given of the Chaos Crags and Cinder Cone eruptive sequences.

A retrospective study on traumatic dental and soft-tissue injuries in preschool children in Zagreb, Croatia.

PubMed

Vuletić, Marko; Škaričić, Josip; Batinjan, Goran; Trampuš, Zdenko; Čuković Bagić, Ivana; Jurić, Hrvoje

2014-02-01

The purpose of this study was to analyze data according to gender, age, cause, number of traumatized teeth, time elapsed before treatment and type of tooth from the records of traumatized children. A retrospective study was conducted in the Department of Paediatric Dentistry at the University Dental Clinic in Zagreb, Croatia using the documentation of 128 patients (61 males and 67 females) aged 1 month to 6 years with injuries of primary teeth between February 2009 and January 2013. Trauma was seen in 217 primary teeth, which implies that the number of injured primary teeth was 1.69 per child. The maxillary central incisors were the most frequently affected teeth (81.1%), they were followed by maxillary lateral incisors, while the least affected were mandibular central incisors. Traumatic dental injuries involved periodontal tissue 2.82 times more frequently than hard dental and pulp tissue. The main cause of teeth injury was fall (67.2%) and the majority of injuries occurred at home (51.6%) (p<0.05). Of 128 patients who received treatment 71 (55.5%) also had soft-tissue injuries. The distribution of soft-tissue injuries by gender (35 males, 36 females) was not statistically significant. Comparing children with soft-tissue injuries and those without them, a statistically significant difference was found in the time of arrival (p<0.01). The results of this study showed the need of informing about preventive measures against falls at home and the methods of providing first aid in dental trauma injuries.

A retrospective study on traumatic dental and soft-tissue injuries in preschool children in Zagreb, Croatia

PubMed Central

Vuletić, Marko; Škaričić, Josip; Batinjan, Goran; Trampuš, Zdenko; Bagić, Ivana Čuković; Jurić, Hrvoje

2014-01-01

The purpose of this study was to analyze data according to gender, age, cause, number of traumatized teeth, time elapsed before treatment and type of tooth from the records of traumatized children. A retrospective study was conducted in the Department of Paediatric Dentistry at the University Dental Clinic in Zagreb. Croatia using the documentation of 128 patients (61 males and 67 females) aged 1 month to 6 years with injuries of primary teeth between February 2009 and January 2013. Trauma was seen in 217 primary teeth, which implies that the number of injured primary teeth was 1.69 per child. The maxillary central incisors were the most frequently affected teeth (81.1%), they were followed by maxillary lateral incisors, while the least affected were mandibular central incisors. Traumatic dental injuries involved periodontal tissue 2.82 times more frequently than hard dental and pulp tissue. The main cause of teeth injury was fall (67.2%) and the majority of injuries occurred at home (51.6%) (p<0.05). Of 128 patients who received treatment 71 (55.5%) also had soft-tissue injuries. The distribution of soft-tissue injuries by gender (35 males, 36 females) was not statistically significant. Comparing children with soft-tissue injuries and those without them, a statistically significant difference was found in the time of arrival (p<0.01). The results of this study showed the need of informing about preventive measures against falls at home and the methods of providing first aid in dental trauma injuries. PMID:24579964

Source apportionment of carbonaceous aerosols in a megacity of northwest China: insights from radiocarbon measurement

NASA Astrophysics Data System (ADS)

Ni, Haiyan; Huang, Rujin; Dusek, Ulrike

2017-04-01

Fine particulate matter (PM2.5) samples were collected from 5 July 2008 to 27 June 2009 at Xi'an, a very polluted megacity in Northwest China. The 24 h averaged PM2.5concentrations (ranged from 32 μg m-3 to 339 μg m-3) were 1-14 times higher than the WHO guideline for 24 h PM2.5(25 μg m-3). In this work, we unambiguously quantify fossil (e.g., vehicle emissions, coal burning etc.) and non-fossil (e.g., biomass burning, cooking, biogenic emissions etc.) contributions to organic carbon (OC) and elemental carbon (EC) of PM2.5using radiocarbon (14C) measurement. In addition, we measured PM2.5 major components and source markers, including OC and EC, ions, trace elements, polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs (o-PAHs), anhydrous sugars and hopanes. The preliminary results of radiocarbon measurements in OC and EC show that the annual mean contributions from fossil-fuel combustion to EC was 76 ± 8% (6 ± 2 μg m-3). The remaining 24 ± 8% (2 ± 1 μg m-3) was attributed to biomass burning, with higher contribution in the cold period (˜33%) compared to the warm period (˜21%), due to enhanced emissions from local biomass burning activities in winter. In contrast with EC, OC was dominated by non-fossil sources, with an annual average of 54 ± 8 % (13 ± 10 μg m-3). Clear seasonal variations were seen in OC concentrations both from fossil fuel (OCff), and from non-fossil sources (OCnf), with maxima in the cold period and minima in the warm period, because of enhanced fossil and non-fossil activities in winter, mainly biomass burning and domestic coal burning. Further source apportionment of OC, including primary/secondary fossil OC, primary/secondary non-fossil OC, will be conducted by combining 14C results with positive matrix factorization (PMF) analysis of organic matter (OM).

Global Cooperation and Competition in the Defense and Aerospace Industries

DTIC Science & Technology

2010-04-26

Tuzla), then regional headquarters (Sarajevo, Bosnia), and, finally, headquarters for UN forces in former Yugoslavia ( Zagreb ). At Zagreb , air... Zagreb , the request would then be 11 A Model I (microeconomic) theorist would hypothesize this came about...Despite staff recommendations for an immediate strike, the UNPROFOR commander at Zagreb chose to include the Dutch government and the regional

Constitutive Parameters of Metamaterial Structures Used for Invisible Cloak Realization

DTIC Science & Technology

2013-10-01

Sipus Dario Bojanjac Marko Bosiljevac Fakultet Elektrotechnike I Racunarstva Unska 3 Zagreb 10000 Croatia EOARD Grant 12-2080...Racunarstva Unska 3 Zagreb 10000 Croatia 8. PERFORMING ORGANIZATION REPORT NUMBER N/A 9. SPONSORING/MONITORING AGENCY NAME(S) AND...University of Zagreb Unska 3 Zagreb , HR-10000, Croatia 13 October 2013 Distribution A: Approved for public release; distribution is

Radiocarbon reservoir between charred seeds and fish bone in Neolithic sites, northeastern Qinghai-Tibetan Plateau

NASA Astrophysics Data System (ADS)

Zhou, A.; Dong, G.; Ren, L.

2017-12-01

Many efforts have been done to understand the reservoir effect of Qinghai Lake, yet no agreement has been reached. Five archaeological sites, located around the junction between the estuary of Rivers and Qinghai Lake, are the earliest Neolithic Age sites in the Qinghai- Tibetan Plateau (QTP), which is critical for understanding patterns of prehistoric human inhabitation in the high plateau extreme environments. This study compares radiocarbon dates of fish bones and terrestrial plant remains uncovered from the same archaeological strata to see whether there was reservoir effect reference to reliable data. Results demonstrate that there were reservoir effects ranging from 300 to 600 years back to 3600 years ago, nevertheless, no reservoir was observed of the modern fish. Besides, stable isotopic analysis illustrated that modern fish consumed similar food to those of millennias ago.

Marine radiocarbon reservoir age variation in Donax obesulus shells from northern Peru: late Holocene evidence for extended El Niño

USGS Publications Warehouse

Etayo-Cadavid, Miguel F.; Andrus, C. Fred T.; Jones, Kevin B.; Hodgins, Gregory W. L.; Sandweiss, Daniel H.; Uceda-Castillo, Sandiago; Quilter, Jeffrey

2013-01-01

For at least 6 m.y., El Niño events have posed the greatest environmental risk on the Peruvian coast. A better understanding of El Niño is essential for predicting future risk and growth in this tropical desert. To achieve this we analyzed archaeological and modern pre-bomb shells from the surf clam Donax for the radiocarbon reservoir effect (ΔR) to characterize late Holocene coastal upwelling conditions in northern Peru (8°14′S). Mean ΔR values from these shells suggest that modern upwelling conditions in this region were likely established between A.D. 539 and A.D. 1578. Our radiocarbon data suggest that upwelling conditions ca. A.D. 539 were less intense than those in modern times. The observed coastal water enrichment in 14C may be consequence of frequent strong El Niño events or extended El Niño–like conditions. These ΔR-inferred marine conditions are in agreement with proposed extended El Niño activity in proxy and archaeological records of ca. A.D. 475–530. Extended El Niño conditions have been linked to political destabilization, societal transformation, and collapse of the Moche civilization in northern Peru. A return to such conditions would have significant impacts on the dense population of this region today and in the near future.

Broadband Epsilon-Near-Zero (ENZ) and Mu-Near-Zero (MNZ) Active Metamaterial

DTIC Science & Technology

2011-08-01

Krois Ivan Bonic Aleksandar Kiricenko Eduardo Ugarte Munoz University of Zagreb Faculty of Electrical Engineering and Computing Department...of Wireless Communications Unska 3 Zagreb , Croatia HR 10 000 EOARD GRANT 10-3030 August 2011 Final Report for 24 August 2010 to 24...ADDRESS(ES) University of Zagreb Faculty of Electrical Engineering and Computing Department of Wireless Communications Unska 3 Zagreb , Croatia

Metamaterial-Based Cylinders Used for Invisible Cloak Realization

DTIC Science & Technology

2011-08-01

Branimir Ivsic Tin Komljenovic University of Zagreb Faculty of Electrical Engineering and Computing Unska 3 Zagreb , Croatia HR-10000...NUMBER 5e. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) University of Zagreb Faculty of Electrical Engineering and Computing...Unska 3 Zagreb , Croatia HR-10000 8. PERFORMING ORGANIZATION REPORT NUMBER N/A 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS

Comparison of sampling methods for radiocarbon dating of carbonyls in air samples via accelerator mass spectrometry

NASA Astrophysics Data System (ADS)

Schindler, Matthias; Kretschmer, Wolfgang; Scharf, Andreas; Tschekalinskij, Alexander

2016-05-01

Three new methods to sample and prepare various carbonyl compounds for radiocarbon measurements were developed and tested. Two of these procedures utilized the Strecker synthetic method to form amino acids from carbonyl compounds with either sodium cyanide or trimethylsilyl cyanide. The third procedure used semicarbazide to form crystalline carbazones with the carbonyl compounds. The resulting amino acids and semicarbazones were then separated and purified using thin layer chromatography. The separated compounds were then combusted to CO2 and reduced to graphite to determine 14C content by accelerator mass spectrometry (AMS). All of these methods were also compared with the standard carbonyl compound sampling method wherein a compound is derivatized with 2,4-dinitrophenylhydrazine and then separated by high-performance liquid chromatography (HPLC).

Radiocarbon dates from the Grotte du Renne and Saint-Césaire support a Neandertal origin for the Châtelperronian

PubMed Central

Hublin, Jean-Jacques; Talamo, Sahra; Julien, Michèle; David, Francine; Connet, Nelly; Bodu, Pierre; Vandermeersch, Bernard; Richards, Michael P.

2012-01-01

The transition from the Middle Paleolithic (MP) to Upper Paleolithic (UP) is marked by the replacement of late Neandertals by modern humans in Europe between 50,000 and 40,000 y ago. Châtelperronian (CP) artifact assemblages found in central France and northern Spain date to this time period. So far, it is the only such assemblage type that has yielded Neandertal remains directly associated with UP style artifacts. CP assemblages also include body ornaments, otherwise virtually unknown in the Neandertal world. However, it has been argued that instead of the CP being manufactured by Neandertals, site formation processes and layer admixture resulted in the chance association of Neanderthal remains, CP assemblages, and body ornaments. Here, we report a series of accelerator mass spectrometry radiocarbon dates on ultrafiltered bone collagen extracted from 40 well-preserved bone fragments from the late Mousterian, CP, and Protoaurignacian layers at the Grotte du Renne site (at Arcy-sur-Cure, France). Our radiocarbon results are inconsistent with the admixture hypothesis. Further, we report a direct date on the Neandertal CP skeleton from Saint-Césaire (France). This date corroborates the assignment of CP assemblages to the latest Neandertals of western Europe. Importantly, our results establish that the production of body ornaments in the CP postdates the arrival of modern humans in neighboring regions of Europe. This new behavior could therefore have been the result of cultural diffusion from modern to Neandertal groups. PMID:23112183

Constraining the sources and cycling of dissolved organic carbon in a large oligotrophic lake using radiocarbon analyses

NASA Astrophysics Data System (ADS)

Zigah, Prosper K.; Minor, Elizabeth C.; McNichol, Ann P.; Xu, Li; Werne, Josef P.

2017-07-01

We measured the concentrations and isotopic compositions of solid phase extracted (SPE) dissolved organic carbon (DOC) and high molecular weight (HMW) DOC and their constituent organic components in order to better constrain the sources and cycling of DOC in a large oligotrophic lacustrine system (Lake Superior, North America). SPE DOC constituted a significant proportion (41-71%) of the lake DOC relative to HMW DOC (10-13%). Substantial contribution of 14C-depleted components to both SPE DOC (Δ14C = 25-43‰) and HMW DOC (Δ14C = 22-32‰) was evident during spring mixing, and depressed their radiocarbon values relative to the lake dissolved inorganic carbon (DIC; Δ14C ∼ 59‰). There was preferential removal of 14C-depleted (older) and thermally recalcitrant components from HMW DOC and SPE DOC in the summer. Contemporary photoautotrophic addition to HMW DOC was observed during summer stratification in contrast to SPE DOC, which decreased in concentration during stratification. Serial thermal oxidation radiocarbon analysis revealed a diversity of sources (both contemporary and older) within the SPE DOC, and also showed distinct components within the HMW DOC. The thermally labile components of HMW DOC were 14C-enriched and are attributed to heteropolysaccharides (HPS), peptides/amide and amino sugars (AMS) relative to the thermally recalcitrant components reflecting the presence of older material, perhaps carboxylic-rich alicyclic molecules (CRAM). The solvent extractable lipid-like fraction of HMW DOC was very 14C-depleted (as old as 1270-2320 14C years) relative to the carbohydrate-like and protein-like substances isolated by acid hydrolysis of HMW DOC. Our data constrain relative influences of contemporary DOC and old DOC, and DOC cycling in a modern freshwater ecosystem.

Ancient human mitochondrial DNA and radiocarbon analysis of archived quids from the Mule Spring Rockshelter, Nevada, USA.

PubMed

Hamilton-Brehm, Scott D; Hristova, Lidia T; Edwards, Susan R; Wedding, Jeffrey R; Snow, Meradeth; Kruger, Brittany R; Moser, Duane P

2018-01-01

Chewed and expectorated quids, indigestible stringy fibers from the roasted inner pulp of agave or yucca root, have proven resilient over long periods of time in dry cave environments and correspondingly, although little studied, are common in archaeological archives. In the late 1960s, thousands of quids were recovered from Mule Spring Rockshelter (Nevada, USA) deposits and stored without consideration to DNA preservation in a museum collection, remaining unstudied for over fifty years. To assess the utility of these materials as repositories for genetic information about past inhabitants of the region and their movements, twenty-one quids were selected from arbitrary excavation depths for detailed analysis. Human mitochondrial DNA sequences from the quids were amplified by PCR and screened for diagnostic single nucleotide polymorphisms. Most detected single nucleotide polymorphisms were consistent with recognized Native American haplogroup subclades B2a5, B2i1, C1, C1c, C1c2, and D1; with the majority of the sample set consistent with subclades C1, C1c, and C1c2. In parallel with the DNA analysis, each quid was radiocarbon dated, revealing a time-resolved pattern of occupancy from 347 to 977 calibrated years before present. In particular, this dataset reveals strong evidence for the presence of haplogroup C1/C1c at the Southwestern edge of the US Great Basin from ~670 to 980 cal YBP, which may temporally correspond with the beginnings of the so-called Numic Spread into the region. The research described here demonstrates an approach which combines targeted DNA analysis with radiocarbon age dating; thus enabling the genetic analysis of archaeological materials of uncertain stratigraphic context. Here we present a survey of the maternal genetic profiles from people who used the Mule Spring Rockshelter and the historic timing of their utilization of a key natural resource.

Radiocarbon variability in the western equatorial Pacific inferred from a high-resolution coral record from Nauru Island

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guilderson, T.P.; Schrag, D.P.; Kashgarian, M.

1998-10-01

We have generated a high resolution coral {Delta}{sup 14}C record spanning the last 50 years to document the seasonal and interannual redistribution of surface waters in the western tropical Pacific. Prebomb (1947{endash}1956) {Delta}{sup 14}C values average {minus}63{per_thousand} and have a total range of 30{per_thousand}. Values begin to increase in 1957, reaching a maximum of 137{per_thousand} in mid-1983. Large interannual variability of up to 80{per_thousand} closely follows the El Ni{tilde n}o-Southern Oscillation (ENSO). During each ENSO warm phase, {Delta}{sup 14}C values begin to increase, reflecting the reduction of low-{sup 14}C water upwelling in the east and the invasion of subtropical watermore » into the western equatorial tropical Pacific. Maximum {Delta}{sup 14}C values are in phase or lag the corresponding sea surface temperature maxima in the eastern tropical Pacific, whereas the rapid return to more negative {Delta}{sup 14}C is in phase with eastern Pacific ENSO indices. The highest-amplitude excursions occur during the 1965/1966 and 1972/1973 events, when the {sup 14}C contrast is highest between the eastern Pacific and subtropics. The 1982/1983 El Ni{tilde n}o, although a larger ENSO event, has a lower {Delta}{sup 14}C amplitude, reflecting the penetration of bomb radiocarbon into the equatorial undercurrent and the reduced contrast in {Delta}{sup 14}C between thermocline and subtropical surface waters at that time. This coral record demonstrates the potential for using similar radiocarbon time series for documenting variability in Pacific shallow circulation over interannual and decadal timescales. {copyright} 1998 American Geophysical Union« less

Estimation of the fossil fuel component in atmospheric CO2 based on radiocarbon measurements at the Beromünster tall tower, Switzerland

NASA Astrophysics Data System (ADS)

Berhanu, Tesfaye A.; Szidat, Sönke; Brunner, Dominik; Satar, Ece; Schanda, Rüdiger; Nyfeler, Peter; Battaglia, Michael; Steinbacher, Martin; Hammer, Samuel; Leuenberger, Markus

2017-09-01

Fossil fuel CO2 (CO2ff) is the major contributor of anthropogenic CO2 in the atmosphere, and accurate quantification is essential to better understand the carbon cycle. Since October 2012, we have been continuously measuring the mixing ratios of CO, CO2, CH4, and H2O at five different heights at the Beromünster tall tower, Switzerland. Air samples for radiocarbon (Δ14CO2) analysis have also been collected from the highest sampling inlet (212.5 m) of the tower on a biweekly basis. A correction was applied for 14CO2 emissions from nearby nuclear power plants (NPPs), which have been simulated with the Lagrangian transport model FLEXPART-COSMO. The 14CO2 emissions from NPPs offset the depletion in 14C by fossil fuel emissions, resulting in an underestimation of the fossil fuel component in atmospheric CO2 by about 16 %. An average observed ratio (RCO) of 13.4 ± 1.3 mmol mol-1 was calculated from the enhancements in CO mixing ratios relative to the clean-air reference site Jungfraujoch (ΔCO) and the radiocarbon-based fossil fuel CO2 mole fractions. The wintertime RCO estimate of 12.5 ± 3.3 is about 30 % higher than the wintertime ratio between in situ measured CO and CO2 enhancements at Beromünster over the Jungfraujoch background (8.7 mmol mol-1) corrected for non-fossil contributions due to strong biospheric contribution despite the strong correlation between ΔCO and ΔCO2 in winter. By combining the ratio derived using the radiocarbon measurements and the in situ measured CO mixing ratios, a high-resolution time series of CO2ff was calculated exhibiting a clear seasonality driven by seasonal variability in emissions and vertical mixing. By subtracting the fossil fuel component and the large-scale background, we have determined the regional biospheric CO2 component that is characterized by seasonal variations ranging between -15 and +30 ppm. A pronounced diurnal variation was observed during summer modulated by biospheric exchange and vertical mixing, while no

Current state of open access to journal publications from the University of Zagreb School of Medicine.

PubMed

Škorić, Lea; Vrkić, Dina; Petrak, Jelka

2016-02-01

To identify the share of open access (OA) papers in the total number of journal publications authored by the members of the University of Zagreb School of Medicine (UZSM) in 2014. Bibliographic data on 543 UZSM papers published in 2014 were collected using PubMed advanced search strategies and manual data collection methods. The items that had "free full text" icons were considered as gold OA papers. Their OA availability was checked using the provided link to full-text. The rest of the UZSM papers were analyzed for potential green OA through self-archiving in institutional repository. Papers published by Croatian journals were particularly analyzed. Full texts of approximately 65% of all UZSM papers were freely available. Most of them were published in gold OA journals (55% of all UZSM papers or 85% of all UZSM OA papers). In the UZSM repository, there were additional 52 freely available authors' manuscripts from subscription-based journals (10% of all UZSM papers or 15% of all UZSM OA papers). The overall proportion of OA in our study is higher than in similar studies, but only half of gold OA papers are accessible via PubMed directly. The results of our study indicate that increased quality of metadata and linking of the bibliographic records to full texts could assure better visibility. Moreover, only a quarter of papers from subscription-based journals that allow self-archiving are deposited in the UZSM repository. We believe that UZSM should consider mandating all faculty members to deposit their publications in UZSM OA repository to increase visibility and improve access to its scientific output.

Current state of open access to journal publications from the University of Zagreb School of Medicine

PubMed Central

Škorić, Lea; Vrkić, Dina; Petrak, Jelka

2016-01-01

Aims To identify the share of open access (OA) papers in the total number of journal publications authored by the members of the University of Zagreb School of Medicine (UZSM) in 2014. Methods Bibliographic data on 543 UZSM papers published in 2014 were collected using PubMed advanced search strategies and manual data collection methods. The items that had “free full text” icons were considered as gold OA papers. Their OA availability was checked using the provided link to full-text. The rest of the UZSM papers were analyzed for potential green OA through self-archiving in institutional repository. Papers published by Croatian journals were particularly analyzed. Results Full texts of approximately 65% of all UZSM papers were freely available. Most of them were published in gold OA journals (55% of all UZSM papers or 85% of all UZSM OA papers). In the UZSM repository, there were additional 52 freely available authors’ manuscripts from subscription-based journals (10% of all UZSM papers or 15% of all UZSM OA papers). Conclusion The overall proportion of OA in our study is higher than in similar studies, but only half of gold OA papers are accessible via PubMed directly. The results of our study indicate that increased quality of metadata and linking of the bibliographic records to full texts could assure better visibility. Moreover, only a quarter of papers from subscription-based journals that allow self-archiving are deposited in the UZSM repository. We believe that UZSM should consider mandating all faculty members to deposit their publications in UZSM OA repository to increase visibility and improve access to its scientific output. PMID:26935617

Resampling soil profiles can constrain large-scale changes in the C cycle: obtaining robust information from radiocarbon measurements

NASA Astrophysics Data System (ADS)

Baisden, W. T.; Prior, C.; Lambie, S.; Tate, K.; Bruhn, F.; Parfitt, R.; Schipper, L.; Wilde, R. H.; Ross, C.

2006-12-01

Soil organic matter contains more C than terrestrial biomass and atmospheric CO2 combined, and reacts to climate and land-use change on timescales requiring long-term experiments or monitoring. The direction and uncertainty of soil C stock changes has been difficult to predict and incorporate in decision support tools for climate change policies. Moreover, standardization of approaches has been difficult because historic methods of soil sampling have varied regionally, nationally and temporally. The most common and uniform type of historic sampling is soil profiles, which have commonly been collected, described and archived in the course of both soil survey studies and research. Resampling soil profiles has considerable utility in carbon monitoring and in parameterizing models to understand the ecosystem responses to global change. Recent work spanning seven soil orders in New Zealand's grazed pastures has shown that, averaged over approximately 20 years, 31 soil profiles lost 106 g C m-2 y-1 (p=0.01) and 9.1 g N m{^-2} y-1 (p=0.002). These losses are unexpected and appear to extend well below the upper 30 cm of soil. Following on these recent results, additional advantages of resampling soil profiles can be emphasized. One of the most powerful applications afforded by resampling archived soils is the use of the pulse label of radiocarbon injected into the atmosphere by thermonuclear weapons testing circa 1963 as a tracer of soil carbon dynamics. This approach allows estimation of the proportion of soil C that is `passive' or `inert' and therefore unlikely to respond to global change. Evaluation of resampled soil horizons in a New Zealand soil chronosequence confirms that the approach yields consistent values for the proportion of `passive' soil C, reaching 25% of surface horizon soil C over 12,000 years. Across whole profiles, radiocarbon data suggest that the proportion of `passive' C in New Zealand grassland soil can be less than 40% of total soil C. Below 30 cm

Stable and radiocarbon isotopic composition of dissolved organic matter in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Walker, B. D.; Druffel, E. R. M.; Kolasinski, J.; Roberts, B. J.; Xu, X.; Rosenheim, B. E.

2017-08-01

Dissolved organic carbon (DOC) is of primary importance to marine ecosystems and the global carbon cycle. Stable carbon (δ13C) and radiocarbon (Δ14C) isotopic measurements are powerful tools for evaluating DOC sources and cycling. However, the isotopic signature of DOC in the Gulf of Mexico (GOM) remains almost completely unknown. Here we present the first DOC Δ14C and δ13C depth profiles from the GOM. Our results suggest the Mississippi River exports large amounts of DOC with an anthropogenic "bomb" Δ14C signature. Riverine DOC is removed and recycled offshore, and some marine production of DOC is observed in the river plume. Offshore profiles show that DOC has higher Δ14C than its Caribbean feed waters, indicative of a modern deep DOC source in the GOM basin. Finally, high DOC with negative δ13C and Δ14C values were observed near the Macondo Wellhead, suggesting a transformation of Deepwater Horizon hydrocarbons into a persistent population of DOC.

Chronometric investigations of the Middle to Upper Paleolithic transition in the Zagros Mountains using AMS radiocarbon dating and Bayesian age modelling.

PubMed

Becerra-Valdivia, Lorena; Douka, Katerina; Comeskey, Daniel; Bazgir, Behrouz; Conard, Nicholas J; Marean, Curtis W; Ollé, Andreu; Otte, Marcel; Tumung, Laxmi; Zeidi, Mohsen; Higham, Thomas F G

2017-08-01

The Middle to Upper Paleolithic transition is often linked with a bio-cultural shift involving the dispersal of modern humans outside of Africa, the concomitant replacement of Neanderthals across Eurasia, and the emergence of new technological traditions. The Zagros Mountains region assumes importance in discussions concerning this period as its geographic location is central to all pertinent hominin migration areas, pointing to both east and west. As such, establishing a reliable chronology in the Zagros Mountains is crucial to our understanding of these biological and cultural developments. Political circumstance, coupled with the poor preservation of organic material, has meant that a clear chronological definition of the Middle to Upper Paleolithic transition for the Zagros Mountains region has not yet been achieved. To improve this situation, we have obtained new archaeological samples for AMS radiocarbon dating from three sites: Kobeh Cave, Kaldar Cave, and Ghār-e Boof (Iran). In addition, we have statistically modelled previously published radiocarbon determinations for Yafteh Cave (Iran) and Shanidar Cave (Iraqi Kurdistan), to improve their chronological resolution and enable us to compare the results with the new dataset. Bayesian modelling results suggest that the onset of the Upper Paleolithic in the Zagros Mountains dates to 45,000-40,250 cal BP (68.2% probability). Further chronometric data are required to improve the precision of this age range. Copyright © 2017 Elsevier Ltd. All rights reserved.

The First Radiocarbon-Constrained Full-Vector Holocene Paleomagnetic Secular Variation Reconstruction for Eastern Canada

NASA Astrophysics Data System (ADS)

Barletta, F.; St-Onge, G.; Stoner, J.; Lajeunesse, P.

2009-05-01

Here we present the first high-resolution Holocene paleomagnetic secular variation (PSV) master curve and relative paleointensity stack constrained by radiocarbon dates for Eastern Canada. This reconstruction is based on seven sedimentary sequences collected from the St. Lawrence Estuary and Gulf from the head to the mouth of the Laurentian Channel. The natural remanent magnetization (NRM), the anhysteretic remanent magnetization (ARM) and the isothermal remanent magnetization (IRM) were measured on u-channel samples at the Paleomagnetism Laboratory of ISMER using a 2G Enterprises cryogenic magnetometer. Magnetic mineralogy was additionally assessed using a recently installed alternative gradient force magnetometer (AGM). The magnetic mineralogy of the Holocene postglacial sediments is mainly carried by low-coercivity ferrimagnetic minerals (most likely magnetite) in the pseudo-single domain size range. The characteristic remanent magnetization (ChRM), assessed by principal component analysis, reveals the presence of a stable and well-defined magnetization characterized by maximum angular deviation (MAD) values generally lower than 5°. Furthermore, ChRM inclinations fluctuate around the expected geocentric axial dipole (GAD) magnetic inclination for the latitude of the coring sites (from 63° to 66°). The similarity of these records on their own independent timescales implies that all of the individual sedimentary sequences record a reliable Holocene PSV record for Eastern Canada. Relative paleointensity (RPI) was estimated by normalizing the NRM by the ARM which provided the best coercivity match. Lastly, the paleomagnetic directional and RPI records were stacked on a common time scale spanning the last ~10 000 cal BP. The smoothed PSV stack reveal centennial- to millennial-scale geomagnetic features concordant with the CALS7K.2 time-varying spherical harmonic model, as well as with the US eastern stack (King and Peck, 2001). Comparisons further a field with the

Radiocarbon dating of magnetic and non magnetic soil fractions as a method to estimate the heterotrophic component of soil respiration in a primary forest of Ghana.

NASA Astrophysics Data System (ADS)

Chiti, T.; Certini, G.; Marzaioli, F.; Valentini, R.

2012-04-01

We estimated the heterotrophic component (Rh) of soil respiration in a primary forest of Ghana by radiocarbon dating, a method we already successfully applied in temperate and Mediterranean forests. In this case, given the advanced stage of alteration of tropical soils, which are thus rich in oxides, we implemented the method on soil fractions obtained by High Gradient Magnetic Separation (HGMS), hence based on different degrees of magnetic susceptibility. In particular, we separated an organic pool associated with magnetic minerals (e.g iron oxides) from an organic pool engaged with non-magnetic minerals. This non destructive method of fractionation, often applied to the finest fraction of soil (clay), is here attempted on the bulk fine earth (< 2 mm). We sampled the soil at 0-5, 5-15, 15-10, and 30-50 cm depth intervals, since a previous study in the same site suggested that only the first 50 cm of soil was enriched in bomb carbon (C younger than 1950). The samples of each layer were sieved at 2 mm and further at 0.5 mm ,so as to have two size fractions: 2 to 0.5 mm and <0.5 mm, and both of them were separated into a magnetic and non magnetic fraction. All the specimens were then investigated in terms of mineralogical assemblage (by X-Ray diffrattometry), chemical structure of the organic component (13C NMR spectroscopy), and 14C concentration (AMS) for inferring the mean residence time (MRT) of the organic component in the soil. Radiocarbon concentration was always higher in the finest SOC fractions (<0.5 mm), with the magnetic fraction always showing an higher 14C concentration than the non magnetic one. The magnetic and non magnetic materials of the coarser fraction (0.5-2 mm) showed quite similar 14C concentrations in all of the soil layers investigated. The composition of the organic matter is different in the different fractions and partly explains the differences in MRT, although a major role in preserving the organics from decomposition is probably played

Radiocarbon variability recorded in coral skeletons from the northwest of Luzon Island, Philippines

NASA Astrophysics Data System (ADS)

Hirabayashi, Shoko; Yokoyama, Yusuke; Suzuki, Atsushi; Miyairi, Yosuke; Aze, Takahiro; Siringan, Fernando; Maeda, Yasuo

2017-12-01

The North Equatorial Current (NEC) bifurcates at the eastern coast of the Philippines and moves northward as the Kuroshio, a North Pacific western boundary current. The NEC bifurcation point and Kuroshio variability are known to be affected by changes in climate such as the El Niño-Southern Oscillation and the pacific decadal oscillation. However, observational data are not sufficient to examine the mechanisms of decadal fluctuation. Here, we report seasonal radiocarbon data recorded from 1968 to 1995 in coral skeletons northwest of Luzon Island. The data suggest that the East Asian winter monsoon is a dominant factor in the seasonal fluctuations in water mass northwest of Luzon Island. Compared with other coral records reported for Guam, Ishigaki, Con Dao, and Hon Tre Island, the data suggest that the area of the Kuroshio loop current through the Luzon Strait decreased from the 1970s to 1980s as a result of the change in Kuroshio transport and the migration of the NEC bifurcation latitude after a regime shift in 1976.

Radiocarbon dating of prehistoric phytoliths: a preliminary study of archaeological sites in China

NASA Astrophysics Data System (ADS)

Zuo, Xinxin; Lu, Houyuan; Zhang, Jianping; Wang, Can; Sun, Guoping; Zheng, Yunfei

2016-05-01

Phytoliths can occlude some organic carbon during their deposition in plants. This carbon fraction is recognised as an ideal dating material because of its high resistance to decomposition and post-deposition contamination at the time of phytolith formation. However, the reliability of phytolith radiocarbon dating has recently been questioned. The development of a new extraction protocol for phytoliths, with paired dating between phytoliths and other materials from the same sediment, may provide further evidence for the reliability of phytolith dating. We present an improved method for extracting phytoliths from soils. We compared the dating of phytoliths and other materials (e.g., charcoal and plant seeds) recovered at the same depth from seven pits at six archaeological sites in China. The estimated ages of the phytoliths and other materials were generally consistent, except for one outlier. We attribute this inconsistency to the post-depositional processes of phytoliths in soil, rather than to the uptake of old carbon from the soil. Our results clearly show the potential for phytolith carbon dating at archaeological sites in the absence of other dating materials.

Toward Radiocarbon Measurement of Individual Amino Acids in Marine Dissolved Organic Matter (DOM): Δ14C Blank Quantification for an HPLC Purification Method.

NASA Astrophysics Data System (ADS)

Bour, A. L.; Broek, T.; Walker, B. D.; Mccarthy, M. D.

2014-12-01

The presence of much of the marine dissolved organic nitrogen (DON) pool as uncharacterized, biologically recalcitrant molecules is a central mystery in the marine nitrogen cycle. Radiocarbon (Δ14C) isotopic measurements have been perhaps the most important data constraining the cycling of dissolved organic matter (DOM), but little Δ14C data specific to DON is available. Amino acids (AAs) are the major component of DON that can be isolated on a molecular level. Δ14C measurements for the operational "protein-like" fraction of DOM in the deep ocean indicate that this compound class has radiocarbon ages greater than several ocean mixing cycles, suggesting remarkable preservation of labile AAs exported from the surface. However, it is possible that the previously defined operational "protein-like" fraction may also contain non-AA material. Radiocarbon measurement of purified individual AAs would provide a more direct and reliable proxy for DON Δ14C age and cycling rate. We present here Δ14C blank characterization of an AA purification method based on HPLC, with on-line fraction collection. This method allows the recovery of unmodified AAs, but accurate measurement of small AA samples that can be extracted from DOM requires a system with extremely low Δ 14C blanks. Here we assess the impact of HPLC purification on the Δ14C age of known amino acids standards. Individual AA standards with contrasting (modern vs. dead) and well- characterized Δ14C ages were processed in a range of sample sizes. The eluted peaks were collected and dried, and measurement of their post-chromatography Δ14C content allowed for determination of the Δ14C blank by method of additions. The same protocol was applied to a mixture of six AA standards, to evaluate tailing effects in consecutive AA peaks of contrasting Δ14C age. AA standards were selected to include both Δ14C modern and dead AAs that elute both early and late in the chromatographic solvent program. We discuss implications

Virtual Reality Adaptive Stimulation in Stress Resistance Training

DTIC Science & Technology

2011-04-01

Kukolja, Branimir Dropuljić University of Zagreb Faculty of Electrical Engineering and Computing, Unska 3, 10000 Zagreb , Croatia Ivica Kostović...Miloš Judaš, Marko Radoš, Milan Radoš, Lana Vasung, Branka Bartolić Spajić University of Zagreb School of Medicine, Croatian Institute for Brain...Research, Šalata 12, 10000 Zagreb , Croatia Svjetlana Doričić, Dalibor Mesić Ministry of Defense, Republic of Croatia ABSTRACT Serious mental health

Comparison of Radiocarbon Ages of Sediments, Plants, and Shells From Coastal Lakes in North Florida

NASA Astrophysics Data System (ADS)

Wang, Y.; Das, O.; Liu, J.; Xu, X.; Roy, R.; Donoghue, J. F.; Means, G. H.

2017-12-01

Coastal lakes sediments are valuable archives of paleo-hurricanes and environmental changes during the late Quaternary provided that they can be accurately dated. Here, we report new radiocarbon (14C) dates derived from various organic and inorganic substrates, including bulk sediment organic matter, plants, shells, particulate organic matter (POM) and dissolved organic matter (DOM), from three coastal lakes in Florida, and compare these ages to evaluate the "reservoir effect" on 14C dating of both organic and inorganic carbon in these lakes. Bulk sediment organic matter yielded consistently older 14C ages than contemporaneous plants and shell fragments, indicating significant radiocarbon deficiencies in sedimentary organic matter in these coastal lakes, caused by influx of old organic carbon from terrestrial sources (such as soils and ancient peat deposits) in the watershed. Several reversals are observed in the 14C ages of bulk sediment organic matter in sediment cores from these lakes, indicating that input of aged organic matter from terrestrial sources into these lakes can vary considerably over time. DOM and POM samples collected at different times also yielded variable 14C signatures, further confirming the temporal variability in the contribution of old organic carbon from terrestrial sources to the lakes. The 14C age discrepancy between bulk sediment organic matter and co-occurring plant fragments or shells varies from less than one hundred years to nearly three thousand years in sediment cores examined in this study. The results show that 14C ages obtained from bulk sediment organic matter in these coastal lakes are unreliable. Analyses of both modern and fossil shells from one of the lakes suggest that the 14C reservoir effect on inorganic carbon in the lake is small and thus freshwater shells (if preserved in the sediment cores) may serve as a good substrate for 14C dating in the absence of plant fragments. However, unidentifiable shell fragments

Effect of anthropogenic activities on atmospheric 14C content and radiocarbon chronologies of the future.

NASA Astrophysics Data System (ADS)

Hajdas, Irka

2017-04-01

Radiocarbon (14C) is a naturally produced radioactive isotope of carbon (T1/2=5700 yrs), which is continuously produced in the atmosphere. This occur in a reaction of thermal neutrons, which are secondary particles, products of cosmic rays reactions with the atmosphere, with nitrogen that is commonly present in the atmosphere. Until the mid 19th century the natural concentration showed temporal variability around the mean value (14C / 12C ratio =1.8 x 10-12). However anthropogenic activity created 2 types effects that are changing the 14C concentration of the atmosphere. Industrial revolution triggered adding 14C free (old) carbon that originates from the burning of fossil fuels (Suess effect). This in the late 19th century and early 20th century atmosphere was becoming older. The nuclear tests in the 1950ties caused additional production of radiocarbon atoms (artificial). The effect has been almost double of the natural production and created an excess 14C activity in the atmosphere and in terrestrial carbon bearing materials. The bomb produced 14C has been identified soon after the tests started but the peak (ca. 100% above the normal levels) reached its maximum in 1963 in the northern Hemisphere where most of the tests took place. In the southern Hemisphere the bomb peak reached lower values (ca. 80 % of normal level) and was delayed by ca. 2 years. After the ban on nuclear tests the atmospheric 14C content began to decrease mainly due to the uptake by the ocean but also due to the above mentioned addition old carbon. Continuous monitoring of the atmospheric 14C ratio during the years that followed the nuclear tests, provide basis for environmental studies. Applications range from studies of ocean circulation, CO2 uptake, carbon storage in soils and peat, root turn over time to the medical, forensic and detection of forgeries. However, the so called ' 14C bomb peak' nearly disappeared due to the combined effect of ocean uptake of CO2 and an input to the

Development of radiocarbon-based methods to investigate atmospheric fossil carbon pollution

NASA Astrophysics Data System (ADS)

Major, István; Vodila, Gergely; Furu, Enikő; Kertész, Zsófia; Haszpra, László; Hajdas, Irka; Molnár, Mihály

2013-04-01

Gaseous and solid state carbon containing compounds significantly affect global climate change based on current atmospheric research results. Major part of the anthropogenic changes of the atmospheric carbon dioxide can be attributed to the combustion of fossil fuels and 95% of their emission is realised in the industrially active areas of the northern hemisphere. Anthropogenic carbonaceous aerosol particles play also a key role in the atmosphere modifying indirectly climate change and the quality of the environment and affecting directly human health. Since September 2008, the CO2 concentration of the air and its specific radiocarbon content (14C) has been monitored in the city of Debrecen (Hungary) and in a rural background site, Hegyhátsál (Hungary). To obtain a more representative view regarding anthropogenic contribution of the atmospheric carbon species, our measurement programme was enhanced by including the investigation of atmospheric aerosols in 2010. An aerosol cascade sampler for continuous monitoring was installed close to the atmospheric CO2 sampling station in the inner city of Debrecen. For 14C measurements, special sample preparation system and method was developed for the tiny total carbon content of the aerosol samples collected synchronously with the carbon dioxide observations. The radiocarbon measurement of the aerosol samples was performed by a high-sensitivity accelerator mass spectrometer (AMS) dedicated to environmental samples (EnvironMICADAS) developed together with ETH Zürich. The δ13C values of the samples were measured by the Dual Inlet system of a Delta PLUS XP Isotope Ratio Mass Spectrometer from the tiny CO2 amount aimed to reserve. The atmospheric fossil CO2 and fossil PM2.5 concentration variations show high similarity in the air of Debrecen city. During the winter heating period, due to the meteorological conditions (frequent thermal inversion, decreasing rate of mixing and upwelling), significantly higher total PM2

No demonstrable association between the Leningrad-Zagreb mumps vaccine strain and aseptic meningitis in a large clinical trial in Egypt.

PubMed

Sharma, H J; Oun, S Aly; Bakr, S S Abou; Kapre, S V; Jadhav, S S; Dhere, R M; Bhardwaj, S

2010-04-01

To address the claim that the Leningrad-Zagreb (L-Z) mumps vaccine strain is causally associated with aseptic meningitis, a prospective, post-marketing safety study was conducted with a measles-mumps-rubella vaccine (MMR) (TRESIVAC(R); Serum Institute of India Ltd., Pune, India), which uses the L-Z strain as its mumps component in Egypt. In all, 453 119 children (65 423 children aged 16-24 months and 329 211 children aged 5-7 years) received MMR. The control groups which, as a result of local health regulations, were slightly younger than vaccinees, comprised 12 253 and 46 232 children, respectively. Using questionnaires, the parents recorded solicited local, systemic and neurological adverse events for up to 42 days post-vaccination. All data were analysed externally on an intention-to-treat basis by individuals not participating in the study. Local and/or systemic reactions were reported in a small percentage of participants, with pain, fever and parotitis being the most common signs among vaccinees in both age groups. No case of aseptic meningitis, encephalitis, anaphylaxis or convulsions was observed in any participant. Thus, in this series of more than 450 000 Egyptian children, the L-Z mumps vaccine strain in this vaccine did not cause aseptic meningitis. The vaccine is considerably cheaper than Western competitors and a valid alternative to other MMR vaccines.

Blade-order-dependent radiocarbon variability in brown seaweed (Undaria pinnatifida) reflected a cold Oyashio water intrusion event in an embayment of the Sanriku coast, northeastern Japan

NASA Astrophysics Data System (ADS)

Satoh, N.; Fukuda, H.; Miyairi, Y.; Yokoyama, Y.; Nagata, T.

2015-12-01

Radiocarbon in dissolved inorganic carbon (DIC) in seawater varies greatly, both geographically and with depth. This "reservoir effect" is thought to be reflected in the radiocarbon content (Δ14C) of marine organisms, via DIC fixation by primary producers and subsequent trophic transfer. The Δ14C of marine organismal soft tissues might thus provide unique information about their habitats, diets, migration and other environmental histories. However, the effectiveness of this approach has yet to be extensively explored, with data on Δ14C variability in soft tissues of marine organisms being markedly limited. Here we examined whether Δ14C values of individual pinnate blades (leaf-like structures) of brown seaweed (Undaria pinnatifida) reflect the Δ14C of DIC in the water current prevailing at the time of blade formation. The study was conducted in Otsuchi Bay located in the Sanriku coastal region, northeastern Japan, where 14C-depleted cold Oyashio current and warm Tsugaru current (high Δ14C) converge, affecting the physiology and growth of marine organisms growing there. U. pinnatifida individuals cultured in the bay (length of saprophytes, 140-215 cm) were harvested in April 2014 and Δ14C of blades were determined by accelerator mass spectrometry. Younger blades formed after the Oyashio water intrusion had significantly lower Δ14C values compared to older blades formed before the event. The Δ14C values of younger and older blades were generally consistent with the Δ14C of DIC in Oyashio (-60.5 ‰) and Tsugaru (24.9 ‰) waters, respectively. Thus, despite possible turnover of organic carbon in seaweed soft tissues, blade-order-dependent Δ14C variability appeared to strongly reflect the Oyashio intrusion event (radiocarbon shift) in the bay.

Titan's Radioactive Haze : Production and Fate of Radiocarbon On Titan

NASA Astrophysics Data System (ADS)

Lorenz, R. D.; Jull, A. J. T.; Swindle, T. D.; Lunine, J. I.

Just as cosmic rays interact with nitrogen atoms in the atmosphere of Earth to gener- ate radiocarbon (14C), the same process should occur in Titan`s nitrogen-rich atmo- sphere. Titan`s atmosphere is thick enough that cosmic ray flux, rather than nitrogen column depth, limits the production of 14 C. Absence of a strong magnetic field and the increased distance from the sun suggest production rates of 9 atom/cm2/s, approx- imately 4 times higher than Earth. On Earth the carbon is rapidly oxidised into CO2. The fate and detectability of 14C on Titan depends on the chemical species into which it is incorporated in Titan's reducing atmosphere : as methane it would be hopelessly diluted even in only the atmosphere (ignoring the other, much more massive carbon reservoirs likely to be present on Titan, like hydrocarbon lakes.) However, in the more likely case that the 14C attaches to the haze that rains out onto the surface (as tholin, HCN or acetylene and their polymers - a much smaller carbon reservoir) , haze in the atmosphere or recently deposited on the surface would therefore be quite intrinsically radioactive. Such activity may modify the haze electrical charging and hence its coag- ulation. Measurements with compact instrumentation on future in-situ missions could place useful constraints on the mass deposition rates of photochemical material on the surface and identify locations where surface deposits of such material are `freshest`.

Herbicide micropollutants in surface, ground and drinking waters within and near the area of Zagreb, Croatia.

PubMed

Fingler, Sanja; Mendaš, G; Dvoršćak, M; Stipičević, S; Vasilić, Ž; Drevenkar, V

2017-04-01

The frequency and mass concentrations of 13 herbicide micropollutants (triazines, phenylureas, chloroacetanilides and trifluralin) were investigated during 2014 in surface, ground and drinking waters in the area of the city of Zagreb and its suburbs. Herbicide compounds were accumulated from water by solid-phase extraction using either octadecylsilica or styrene-divinylbenzene sorbent cartridges and analysed either by high-performance liquid chromatography with UV-diode array detector or gas chromatography with mass spectrometric detection. Atrazine was the most frequently detected herbicide in drinking (84 % of samples) and ground (61 % of samples) waters in mass concentrations of 5 to 68 ng L -1 . It was followed by metolachlor and terbuthylazine, the former being detected in 54 % of drinking (up to 15 ng L -1 ) and 23 % of ground (up to 100 ng L -1 ) waters, and the latter in 45 % of drinking (up to 20 ng L -1 ) and 26 % of ground (up to 25 ng L -1 ) water samples. Acetochlor was the fourth most abundant herbicide in drinking waters, detected in 32 % of samples. Its mass concentrations of 107 to 117 ng L -1 in three tap water samples were the highest of all herbicides measured in the drinking waters. The most frequently (62 % of samples) and highly (up to 887 ng L -1 ) detected herbicide in surface waters was metolachlor, followed by terbuthylazine detected in 49 % of samples in mass concentrations of up to 690 ng L -1 , and atrazine detected in 30 % of samples in mass concentrations of up to 18 ng L -1 . The seasonal variations in herbicide concentrations in surface waters were observed for terbuthylazine, metolachlor, acetochlor, chlortoluron and isoproturon with the highest concentrations measured from April to August.

Prevalence of apical periodontitis and quality of root canal fillings in population of Zagreb, Croatia: a cross-sectional study

PubMed Central

Matijević, Jurica; Čižmeković Dadić, Tina; Prpić Mehičić, Goranka; Anić, Ivica; Šlaj, Mladen; Jukić Krmek, Silvana

2011-01-01

Aim To determine the prevalence of apical periodontitis and assess the quality of endodontic fillings in the population of the city of Zagreb, Croatia. Methods A total of 1462 orthopantomograms from new patients at 6 different dental practices was analyzed during 2006 and 2007. The presence of periapical lesions was determined by using the periapical index score (PAI). The quality of endodontic fillings was assessed according to the filling length and homogeinicity. Data were analyzed using t test and ANOVA with Scheffe post-hoc test. Results There were 75.9% of participants with endodontically treated teeth and 8.5% of all teeth were endodontically treated. Only 34.2% of endodontically treated roots had adequate root canal filling length, while 36.2% of root canal fillings had homogenous appearance. From the total number of teeth with intracanal post, 17.5% had no visible root canal filling. Using PAI 3 as a threshold value for apical periodontitis, periapical lesions were detected in 8.5% of teeth. Adequate quality of root canal fillings was associated with a lower prevalence of periapical lesions. Conclusion We found a large proportion of endodontically treated teeth with apical periodontitis and a correlation between the quality of endodontic filling and the prevalence of periapical lesions. This all suggests that it is necessary to improve the quality of endodontic treatment in order to reduce the incidence and prevalence of apical periodontitis. PMID:22180266

Mammoths inside the Alps during the last glacial period: Radiocarbon constraints from Austria and palaeoenvironmental implications

NASA Astrophysics Data System (ADS)

Spötl, Christoph; Reimer, Paula J.; Göhlich, Ursula B.

2018-06-01

This study examines remains of the woolly mammoth (Mammuthus primigenius) found inside the Austrian Alps, an area occupied by an extensive ice-stream network during the Last Glacial Maximum. The data demonstrate that these cold steppe-adapted animals locally migrated several tens of kilometers into alpine valleys. Radiocarbon analyses constrain the age of these fossils to the first half of Marine Isotope Stage 3, documenting ice-free conditions in major valleys at that time. We also provide a list of all traceable Austrian sites of Mammuthus primigenius, totaling about 230 localities, compiled through 15 museums and collections in Austria. The vast majority of these findings are from the corridors of the Danube and Mur rivers and their tributaries and the adjacent loess-covered foreland of the Alps, areas that were never ice-covered during Pleistocene glaciations.

Radiocarbon ages and age models for the past 30,000 years in Bear Lake, Utah and Idaho

USGS Publications Warehouse

Colman, Steven M.; Rosenbaum, J.G.; Kaufman, D.S.; Dean, W.E.; McGeehin, J.P.

2009-01-01

Radiocarbon analyses of pollen, ostracodes, and total organic carbon (TOC) provide a reliable chronology for the sediments deposited in Bear Lake over the past 30,000 years. The differences in apparent age between TOC, pollen, and carbonate fractions are consistent and in accord with the origins of these fractions. Comparisons among different fractions indicate that pollen sample ages are the most reliable, at least for the past 15,000 years. The post-glacial radiocarbon data also agree with ages independently estimated from aspartic acid racemization in ostracodes. Ages in the red, siliclastic unit, inferred to be of last glacial age, appear to be several thousand years too old, probably because of a high proportion of reworked, refractory organic carbon in the pollen samples. Age-depth models for five piston cores and the Bear Lake drill core (BL00-1) were constructed by using two methods: quadratic equations and smooth cubic-splinefits. The two types of age models differ only in detail for individual cores, and each approach has its own advantages. Specific lithological horizons were dated in several cores and correlated among them, producing robust average ages for these horizons. The age of the correlated horizons in the red, siliclastic unit can be estimated from the age model for BL00-1, which is controlled by ages above and below the red, siliclastic unit. These ages were then transferred to the correlative horizons in the shorter piston cores, providing control for the sections of the age models in those cores in the red, siliclastic unit. These age models are the backbone for reconstructions of past environmental conditions in Bear Lake. In general, sedimentation rates in Bear Lake have been quite uniform, mostly between 0.3 and 0.8 mm yr-1 in the Holocene, and close to 0.5 mm yr-1 for the longer sedimentary record in the drill core from the deepest part of the lake. Copyright ?? 2009 The Geological Society of America.

Radiocarbon Analysis of Individual Amino Acids: Carbon Blank Quantification for a Small-Sample High-Pressure Liquid Chromatography Purification Method.

PubMed

Bour, Amy L; Walker, Brett D; Broek, Taylor A B; McCarthy, Matthew D

2016-04-05

Compound-specific radiocarbon analysis (CSRA) of amino acids (AAs) is of great interest as a proxy for organic nitrogen (N) cycling rates, dating archeological bone collagen, and investigating processes shaping the biogeochemistry of global N reservoirs. However, recoverable quantities of individual compounds from natural samples are often insufficient for radiocarbon ((14)C) analyses (<50 μg C). Constraining procedural carbon (C) blanks and their isotopic contributions is critical for reporting of accurate CSRA measurements. Here, we report the first detailed quantification of C blanks (including sources, magnitudes, and variability) for a high-pressure liquid chromatography (HPLC) method designed to purify individual AAs from natural samples. We used pairs of AA standards with either modern (M) or dead (D) fraction modern (Fm) values to quantify MC and DC blanks within several chromatographic regions. Blanks were determined for both individual and mixed AA standard injections with peak loadings ranging from 10 to 85 μg C. We found 0.8 ± 0.4 μg of MC and 1.0 ± 0.5 μg of DC were introduced by downstream sample preparation (drying, combustion, and graphitization), which accounted for essentially the entire procedural blank for early eluting AAs. For late-eluting AAs, higher eluent organic content and fraction collected volumes contributed to total blanks of 1.5 ± 0.75 μg of MC and 3.0 ± 1.5 μg of DC. Our final measurement uncertainty for 20 μg of C of most AAs was ±0.02 Fm, although sample size requirements are larger for similar uncertainty in late-eluting AAs. These results demonstrate the first CSRA protocol for many protein AAs with uncertainties comparable to the lowest achieved in prior studies.

76 FR 19788 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-Telemanagement Forum

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-08

...Telematics, Inc., Atlanta, GA; Inducta d.o.o., Zagreb, CROATIA; Infinite Infosoft Services Pvt Ltd, Gurgaon, INDIA; ING Bank N.V., Amsterdam, NETHERLANDS; integracija od-do d.o.o., Zagreb, CROATIA; Intraway Corp...; HughesTelematics to HughesTelematics, Inc., Atlanta, GA; Inducta to Inducta d.o.o., Zagreb, CROATIA...

Centuries of marine radiocarbon reservoir age variation within archaeological Mesodesma Donacium shells from Southern Peru

USGS Publications Warehouse

Jones, K.B.; Hodgins, G.W.L.; Etayo-Cadavid, M. F.; Andrus, C.F.T.; Sandweiss, D.H.

2010-01-01

Mollusk shells provide brief (<5 yr per shell) records of past marine conditions, including marine radiocarbon reservoir age (R) and upwelling. We report 21 14C ages and R calculations on small (~2 mg) samples from 2 Mesodesma donacium (surf clam) shells. These shells were excavated from a semi-subterranean house floor stratum 14C dated to 7625 ?? 35 BP at site QJ-280, Quebrada Jaguay, southern Peru. The ranges in marine 14C ages (and thus R) from the 2 shells are 530 and 170 14C yr; R from individual aragonite samples spans 130 ?? 60 to 730 ?? 170 14C yr. This intrashell 14C variability suggests that 14C dating of small (time-slice much less than 1 yr) marine samples from a variable-R (i.e. variable-upwelling) environment may introduce centuries of chronometric uncertainty. ?? 2010 by the Arizona Board of Regents on behalf of the University of Arizona.

10th International Meeting on Cholinesterases

DTIC Science & Technology

2009-10-01

NATIVE, PHOSPHYLATED AND AGED HUMAN ACETYLCHOLINESTERASE AND BUTYRYLCHOLINESTERASE Page 9 Zrinka Kovarik ( Zagreb , Croatia): OXIME-ASSISTED...REACTIVATION OF PHOSPHORYLATED BUTYRYLCHOLINESTERASE Goran Šinko ( Zagreb , Croatia): INTERACTIONS OF PYRIDINIUM OXIMES WITH ACETYLCHOLINESTERASE...OF CHOLINESTERASES IN THE BRAIN Ninoslav Mimica ( Zagreb , Croatia): THE CHOLINESTERASE INHIBITORS – CURRENT CLINICAL VIEW AND CROATIAN REALITY

Radiocarbon constraints on the extent and evolution of the South Pacific glacial carbon pool

PubMed Central

Ronge, T. A.; Tiedemann, R.; Lamy, F.; Köhler, P.; Alloway, B. V.; De Pol-Holz, R.; Pahnke, K.; Southon, J.; Wacker, L.

2016-01-01

During the last deglaciation, the opposing patterns of atmospheric CO2 and radiocarbon activities (Δ14C) suggest the release of 14C-depleted CO2 from old carbon reservoirs. Although evidences point to the deep Pacific as a major reservoir of this 14C-depleted carbon, its extent and evolution still need to be constrained. Here we use sediment cores retrieved along a South Pacific transect to reconstruct the spatio-temporal evolution of Δ14C over the last 30,000 years. In ∼2,500–3,600 m water depth, we find 14C-depleted deep waters with a maximum glacial offset to atmospheric 14C (ΔΔ14C=−1,000‰). Using a box model, we test the hypothesis that these low values might have been caused by an interaction of aging and hydrothermal CO2 influx. We observe a rejuvenation of circumpolar deep waters synchronous and potentially contributing to the initial deglacial rise in atmospheric CO2. These findings constrain parts of the glacial carbon pool to the deep South Pacific. PMID:27157845

Atmospheric Observations of Carbon Dioxide and Quantification of Fossil Fuel Carbon Dioxide and Emission Inventories using Radiocarbon in the Korean Peninsula during the KORUS-AQ Field Campaign

NASA Astrophysics Data System (ADS)

Choi, Y.; DiGangi, J. P.; Diskin, G. S.; Nowak, J. B.; Halliday, H.; Pusede, S.; Arellano, A. F., Jr.; Tang, W.; Knote, C. J.; Woo, J. H.; Lee, Y.; Kim, Y.; Bu, C.; Blake, D. R.; Simpson, I. J.; Blake, N. J.; Xu, X.

2017-12-01

This presentation discusses a unique data set of airborne in situ carbon dioxide (CO2) and carbon monoxide (CO) soundings and radiocarbon measurements to accurately quantify anthropogenic CO2 emissions from the total measured CO2 signal. Precise assessment of fossil fuel (FF) CO2 gives a better understanding of source contributions to emission inventories in the study region. Fast response (1Hz) and high precision (<0.1 ppm) in situ measurements of atmospheric CO2 and other trace gases, including 60 CO2 radiocarbon measurements from flask samples, onboard the NASA DC-8 aircraft during KORUS-AQ (May-June, 2016), were used in combination with an updated emissions inventory named NIER/KU_CREATE (Comprehensive Regional Emissions inventory for Atmospheric Transport Experiment) to gain a better understanding of pollution characteristics in the study region. Fractional FF CO2 contributions were calculated using radiocarbon and in-situ CO2 concentrations. These quantified FF CO/CO2 ratios from the in situ measurements were compared to the updated emissions inventory. Distinctly higher ratios were found in Chinese outflow, relative to those from the Korean Peninsula, and the emission inventory shows higher CO/CO2 ratios than measurements both in the Korea and China regions. This quantified FF CO/CO2 ratio was applied to continuous measurements of in-situ CO and CO2 and used to identify the portion of biogenic CO2 observed during the field campaign (the biospheric contribution to the total CO2 is typically 20-30 % in this regions). This continuous partitioning of biogenic and anthropogenic sources will give a better understanding of diurnal variations of local sources and will be helpful for the evaluation of emission inventories, where mega-city fossil fuel combustion sources mix with biospheric sources. Also discussed is the comparison of quantified FF CO/CO2 ratios with the CAMS (Copernicus Atmosphere Monitoring Service) simulated products ratios and local source

Source apportionment of fine particulate matter organic carbon in Shenzhen, China by chemical mass balance and radiocarbon methods.

PubMed

Al-Naiema, Ibrahim M; Yoon, Subin; Wang, Yu-Qin; Zhang, Yuan-Xun; Sheesley, Rebecca J; Stone, Elizabeth A

2018-09-01

Chemical mass balance (CMB) modeling and radiocarbon measurements were combined to evaluate the sources of carbonaceous fine particulate matter (PM 2.5 ) in Shenzhen, China during and after the 2011 summer Universiade games when air pollution control measurements were implemented to achieve air quality targets. Ambient PM 2.5 filter samples were collected daily at two sampling sites (Peking University Shenzhen campus and Longgang) over 24 consecutive days, covering the controlled and uncontrolled periods. During the controlled period, the average PM 2.5 concentration was less than half of what it was after the controls were lifted. Organic carbon (OC), organic molecular markers (e.g., levoglucosan, hopanes, polycyclic aromatic hydrocarbons), and secondary organic carbon (SOC) tracers were all significantly lower during the controlled period. After pollution controls ended, at Peking University, OC source contributions included gasoline and diesel engines (24%), coal combustion (6%), biomass burning (12.2%), vegetative detritus (2%), biogenic SOC (from isoprene, α-pinene, and β-caryophyllene; 7.1%), aromatic SOC (23%), and other sources not included in the model (25%). At Longgang after the controls ended, similar source contributions were observed: gasoline and diesel engines (23%), coal combustion (7%), biomass burning (17.7%), vegetative detritus (1%), biogenic SOC (from isoprene, α-pinene, and β-caryophyllene; 5.3%), aromatic SOC (13%), and other sources (33%). The contributions of the following sources were smaller during the pollution controls: biogenic SOC (by a factor of 10-16), aromatic SOC (4-12), coal combustion (1.5-6.8), and biomass burning (2.3-4.9). CMB model results and radiocarbon measurements both indicated that fossil carbon dominated over modern carbon, regardless of pollution controls. However, the CMB model needs further improvement to apportion contemporary carbon (i.e. biomass burning, biogenic SOC) in this region. This work defines the

Ancient dissolved methane in inland waters at low concentrations revealed by a new collection method for radiocarbon (^{14}C) analysis

NASA Astrophysics Data System (ADS)

Dean, Joshua F.; Billett, Michael F.; Murray, Callum; Garnett, Mark H.

2017-04-01

Methane (CH4) is a powerful greenhouse gas and is released to the atmosphere from freshwater systems in numerous biomes globally. Radiocarbon (14C) analysis of methane can provide unique information about its age, source and rate of cycling in natural environments. Methane is often released from aquatic sediments in bubbles (ebullition), but dissolved methane is also present in lakes and streams at lower concentrations, and may not be of the same age or source. Obtaining sufficient non-ebullitive aquatic methane for 14C analysis remains a major technical challenge. Previous studies have shown that freshwater methane, in both dissolved and ebullitive form, can be significantly older than other forms of aquatic carbon (C), and it is therefore important to characterise this part of the terrestrial C balance. We present a novel method to capture sufficient amounts of dissolved methane from freshwater environments for 14C analysis by circulating water across a hydrophobic, gas-permeable membrane and collecting the methane in a large collapsible vessel. The results of laboratory and field tests show that reliable dissolved δ13CH4 and 14CH4 samples can be readily collected over short time periods (˜4 to 24 hours), at relatively low cost and from a variety of surface water types. The initial results further support previous findings that dissolved methane can be significantly older than other forms of aquatic C, especially in organic-rich catchments, and is currently unaccounted for in many terrestrial C balances and models. This method is suitable for use in remote locations, and could potentially be used to detect the leakage of unique 14CH4 signatures from point sources into waterways, e.g. coal seam gas and landfill gas.

Teaching Instrumentation and Methodology in Human Motion Analysis

DTIC Science & Technology

2001-10-25

TEACHING INSTRUMENTATION AND METHODOLOGY IN HUMAN MOTION ANALYSIS V. Medved Faculty of Physical Education , University of Zagreb, Zagreb, Croatia...the introducement of teaching curricula to implement the apropriate knowledge. Problems are discussed of educating professionals and disseminating...University of Zagreb, undergraduate teaching of locomotion biomechanics is provided only at the Faculty of Physical Education . Following a need to teach

Identifying sources of dissolved organic carbon in agriculturally dominated rivers using radiocarbon age dating: Sacramento-San Joaquin River Basin, California

USGS Publications Warehouse

Sickman, James O.; DiGiorgio, Carol L.; Davisson, M. Lee; Lucero, Delores M.; Bergamaschi, Brian A.

2010-01-01

We used radiocarbon measurements of dissolved organic carbon (DOC) to resolve sources of riverine carbon within agriculturally dominated landscapes in California. During 2003 and 2004, average Δ14C for DOC was −254‰ in agricultural drains in the Sacramento–San Joaquin Delta, −218‰ in the San Joaquin River, −175‰ in the California State Water Project and −152‰ in the Sacramento River. The age of bulk DOC transiting the rivers of California’s Central Valley is the oldest reported for large rivers and suggests wide-spread loss of soil organic matter caused by agriculture and urbanization. Using DAX 8 adsorbent, we isolated and measured 14C concentrations in hydrophobic acid fractions (HPOA); river samples showed evidence of bomb-pulse carbon with average Δ14C of 91 and 76‰ for the San Joaquin and Sacramento Rivers, respectively, with older HPOA, −204‰, observed in agricultural drains. An operationally defined non-HPOA fraction of DOC was observed in the San Joaquin River with seasonally computed Δ14C values of between −275 and −687‰; the source of this aged material was hypothesized to be physically protected organic-matter in high clay-content soils and agrochemicals (i.e., radiocarbon-dead material) applied to farmlands. Mixing models suggest that the Sacramento River contributes about 50% of the DOC load in the California State Water Project, and agricultural drains contribute approximately one-third of the load. In contrast to studies showing stabilization of soil carbon pools within one or two decades following land conversion, sustained loss of soil organic matter, occurring many decades after the initial agricultural-land conversion, was observed in California’s Central Valley.

The 3.6 ka Aniakchak tephra in the Arctic Ocean: a constraint on the Holocene radiocarbon reservoir age in the Chukchi Sea

NASA Astrophysics Data System (ADS)

Pearce, Christof; Varhelyi, Aron; Wastegård, Stefan; Muschitiello, Francesco; Barrientos, Natalia; O'Regan, Matt; Cronin, Thomas M.; Gemery, Laura; Semiletov, Igor; Backman, Jan; Jakobsson, Martin

2017-04-01

The caldera-forming eruption of the Aniakchak volcano in the Aleutian Range on the Alaskan Peninsula at 3.6 cal kyr BP was one of the largest Holocene eruptions worldwide. The resulting ash is found as a visible sediment layer in several Alaskan sites and as a cryptotephra on Newfoundland and Greenland. This large geographic distribution, combined with the fact that the eruption is relatively well constrained in time using radiocarbon dating of lake sediments and annual layer counts in ice cores, makes it an excellent stratigraphic marker for dating and correlating mid-late Holocene sediment and paleoclimate records. This study presents the outcome of a targeted search for the Aniakchak tephra in a marine sediment core from the Arctic Ocean, namely Core SWERUS-L2-2-PC1 (2PC), raised from 57 m water depth in Herald Canyon, western Chukchi Sea. High concentrations of tephra shards, with a geochemical signature matching that of Aniakchak ash, were observed across a more than 1.5 m long sediment sequence. Since the primary input of volcanic ash is through atmospheric transport, and assuming that bioturbation can account for mixing up to ca. 10 cm of the marine sediment deposited at the coring site, the broad signal is interpreted as sustained reworking at the sediment source input. The isochron is therefore placed at the base of the sudden increase in tephra concentrations rather than at the maximum concentration. This interpretation of major reworking is strengthened by analysis of grain size distribution which points to ice rafting as an important secondary transport mechanism of volcanic ash. Combined with radiocarbon dates on mollusks in the same sediment core, the volcanic marker is used to calculate a marine radiocarbon reservoir age offset ΔR = 477 ± 60 years. This relatively high value may be explained by the major influence of typically carbon-old Pacific waters, and it agrees well with recent estimates of ΔR along the northwest Alaskan coast

Investigations on alluvial deposits through borehole stratigraphy, radiocarbon dating and passive seismic technique (Carnic Alps, NE Italy)

NASA Astrophysics Data System (ADS)

Viero, Alessia; Marchi, Lorenzo; Cavalli, Marco; Crema, Stefano; Fontana, Alessandro; Mozzi, Paolo; Venturini, Corrado

2016-04-01

Alluvial sediment investigations provide fundamental tools to infer the processes that control geomorphological evolution of mountain environments. By analyzing sediment stratigraphy in depth, it is possible to retrieve the source, the geology, the time of deposition, the relative distance travelled by material as well as to distinguish among different type of transport (i.e., gravitational, fluvial or glacial). In this work, we present a combination of log stratigraphy, radiocarbon dating and geophysical surveys carried out on the valley floor of the But River (Carnic Alps, North East Italy). The But River basin drains an area of 326 km2 with a range in elevation from 2769 to 323 m a.s.l.; the bedrock mainly consists of carbonates and quartz arenites with minor inclusions of effusive rocks. After Pleistocene the gravitational deposits from mountain slopes have impounded the But River several times. In particular, we analyzed a sector of the upper portion of the But valley close to the confluence of the Moscardo Torrent, frequently affected by debris flows. A borehole was drilled in the But River floodplain, at the intersection with the Moscardo Torrent alluvial fan, down to a depth of 80 m. The analysis of the core samples allowed discerning three sedimentary levels rich in clay and organic materials, which testify the presence of small dam lakes, originated from the Moscardo debris-flow deposits. Three samples of wood and plant debris were collected from 13, 14 and 23 m of depth, respectively. They were analyzed through radiocarbon dating in order to determine the age of the lakes and, thus, to infer the activity of the debris flows building the Moscardo cone. The calibrated ages of the 3 samples are close to the younger limit of the radiocarbon method indicating a fast aggradation of the valley floor, starting from a period ranging between 1450 - 1632 AD. Historical maps and documents confirm the presence of the lakes until 19th century and they permit to assess

Variations of anthropogenic CO2 in urban area deduced by radiocarbon concentration in modern tree rings.

PubMed

Rakowski, Andrzej Z; Nakamura, Toshio; Pazdur, Anna

2008-10-01

Radiocarbon concentration in the atmosphere is significantly lower in areas where man-made emissions of carbon dioxide occur. This phenomenon is known as Suess effect, and is caused by the contamination of clean air with non-radioactive carbon from fossil fuel combustion. The effect is more strongly observed in industrial and densely populated urban areas. Measurements of carbon isotope concentrations in a study area can be compared to those from areas of clear air in order to estimate the amount of carbon dioxide emission from fossil fuel combustion by using a simple mathematical model. This can be calculated using the simple mathematical model. The result of the mathematical model followed in this study suggests that the use of annual rings of trees to obtain the secular variations of 14C concentration of atmospheric CO2 can be useful and efficient for environmental monitoring and modeling of the carbon distribution in local scale.

Chronostratigraphical Subdivision of the Late Glacial and the Holocene for the Alaska Region

NASA Astrophysics Data System (ADS)

Michczynska, D. J.; Hajdas, I.

2009-04-01

Our work is a kind of so called data mining. The first step of our work was collection of the radiocarbon data for samples coming from Alaska. We construct data base using Radiocarbon Measurements Lists published by different radiocarbon laboratories (mainly in the journal 'Radiocaron'). The next step was careful analysis of collected dates. We excluded from our analysis all dates suspected of contamination by younger or older organic matter. Such fact could be stated, for instance, on the base of inconsistency of radiocarbon age and stratigraphy or palynology. Finally, we calibrated whole large set of chosen radiocarbon dates and construct probability density function (PDF). Analysis of the shape of PDF was the subject of the previous research (eg. Michczynska and Pazdur, 2004; Macklin et al., 2006; Starkel et al., 2006, Michczynska et al., 2007). In our analysis we take into account the distinct tendency to collect samples from specific horizons. It is a general rule to take samples for radiocarbon dating from places of visible sedimentation changes or changes in palynological diagram. Therefore the culminations of the PDF represent periods of environmental changes and could be helpful in identifying the chronostratigraphical boundaries on the calendar time scale. References: Michczyńska D.J., Pazdur A., 2004. A shape analysis of cumulative probability density function of radiocarbon dates set in the study of climate change in Late Glacial and Holocene. Radiocarbon 46(2): 733-744. Michczyńska D.J., Michczyński A., Pazdur A. 2007. Frequency distribution of radiocarbon dates as a tool for reconstructing environmental changes. Radiocarbon 49(2): 799-806. Macklin M.G., Benito G., Gregory K.J., Johnstone E., Lewin J., Michczyńska D.J., Soja R., Starkel L., Thorndycraft V.R., 2006. Past hydrological events reflected in the Holocene fluvial record of Europe. CATENA 66: 145-154. Starkel L., Soja R., Michczyńska D.J., 2006. Past hydrological events reflected in

[Mumps vaccine virus transmission].

PubMed

Otrashevskaia, E V; Kulak, M V; Otrashevskaia, A V; Karpov, I A; Fisenko, E G; Ignat'ev, G M

2013-01-01

In this work we report the mumps vaccine virus shedding based on the laboratory confirmed cases of the mumps virus (MuV) infection. The likely epidemiological sources of the transmitted mumps virus were children who were recently vaccinated with the mumps vaccine containing Leningrad-Zagreb or Leningrad-3 MuV. The etiology of the described cases of the horizontal transmission of both mumps vaccine viruses was confirmed by PCR with the sequential restriction analysis.

Tritium and radiocarbon in the western North Pacific waters: post-Fukushima situation.

PubMed

Kaizer, Jakub; Aoyama, Michio; Kumamoto, Yuichiro; Molnár, Mihály; Palcsu, László; Povinec, Pavel P

2018-04-01

Impact of the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident on tritium ( 3 H) and radiocarbon ( 14 C) levels in the water column of the western North Pacific Ocean in winter 2012 is evaluated and compared with radiocesium ( 134,137 Cs) data collected for the same region. Tritium concentrations in surface seawater, varying between 0.4 and 2.0 TU (47.2-236 Bq m -3 ), follow the Fukushima radiocesium trend, however, some differences in the vertical profiles were observed, namely in depths of 50-400 m. No correlation was visible in the case of 14 C, whose surface Δ 14 C levels raised from negative values (about -40‰) in the northern part of transect, to positive values (∼68‰) near the equator. Homogenously mixed 14 C levels in the subsurface layers were observed at all stations. Sixteen surface (from 30 in total) and 6 water profile (from 7) stations were affected by the Fukushima tritium. Surface and vertical profile data together with the calculated water column inventories indicate that the total amount of the FNPP1-derived tritium deposited to the western North Pacific Ocean was 0.7 ± 0.3 PBq. No clear impact of the Fukushima accident on 14 C levels in the western North Pacific was observed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Noble gases, stable isotopes, and radiocarbon as tracers of flow in the Dakota aquifer, Colorado and Kansas

USGS Publications Warehouse

Clark, J.F.; Davisson, M.L.; Hudson, G.B.; Macfarlane, P.A.

1998-01-01

A suite of chemical and isotope tracers (dissolved noble gases, stable isotopes of water, radiocarbon, and CI) have been analyzed along a flow path in the Dakota aquifer system to determine likely recharge sources, ground water residence times, and the extent of mixing between local and intermediate flow systems, presumably caused by large well screens. Three water types were distinguished with the tracers, each having a very different history. Two of the water types were found in south-eastern Colorado where the Dakota is poorly confined. The tracer data suggest that the first group recharged locally during the last few thousand years and the second group was composed of ground water that recharged earlier during a cooler climate, presumably during the last glacial period (LGP) and mixed aged water. The paleotemperature record archived in this groundwater system indicates that south-eastern Colorado was about 5??C cooler during the LGP than during the late Holocene. Similar temperature changes derived from dissolved noble gases in other aquifer systems have been reported earlier for the south-western United States. The third water type was located down gradient of the first two in the confined Dakota in western and central Kansas. Groundwater residence time of this water mass is on the order of 104-105 yrs and its recharge location is near the Colorado and Kansas border down gradient of the other water types. The study shows the importance of using multiple tracers when investigating ground water systems.A suite of chemical and isotope tracers (dissolved noble gases, stable isotopes of water, radiocarbon, and CL) were analyzed along a flow path in the Dakota aquifer system to determine likely recharge sources, ground water residence times, and the extent of mixing between local and intermediate flow systems. Three water types were distinguished with the tracers, each having a very different history. Two of the water types were located in south-eastern Colorado

Numerical dating of a Late Quaternary spit-shoreline complex at the northern end of Silver Lake playa, Mojave Desert, California: A comparison of the applicability of radiocarbon, luminescence, terrestrial cosmogenic nuclide, electron spin resonance, U-series and amino acid racemization methods

USGS Publications Warehouse

Owen, L.A.; Bright, Jordon; Finkel, R.C.; Jaiswal, M.K.; Kaufman, D.S.; Mahan, S.; Radtke, U.; Schneider, J.S.; Sharp, W.; Singhvi, A.K.; Warren, C.N.

2007-01-01

A Late Quaternary spit-shoreline complex on the northern shore of Pleistocene Lake Mojave of southeastern California, USA was studied with the goal of comparing accelerator mass spectrometry (AMS) radiocarbon, luminescence, electron spin resonance (ESR), terrestrial cosmogenic radionuclide (TCN) surface exposure, amino acid racemization (AAR) and U-series dating methods. The pattern of ages obtained by the different methods illustrates the complexity of processes acting in the lakeshore environment and highlights the utility of a multi-method approach. TCN surface exposure ages (mostly ???20-30 ka) record the initial erosion of shoreline benches, whereas radiocarbon ages on shells (determined in this and previous studies) within the spit, supported by AAR data, record its construction at fluctuating lake levels from ???16 to 10 ka. Luminescence ages on spit sediment (???6-7 ka) and ESR ages on spit shells (???4 ka) are anomalously young relative to radiocarbon ages of shells within the same deposits. The significance of the surprisingly young luminescence ages is not clear. The younger ESR ages could be a consequence of post-mortem enrichment of U in the shells. High concentrations of detrital thorium in tufa coating spit gravels inhibited the use of single-sample U-series dating. Detailed comparisons such as this provide one of the few means of assessing the accuracy of Quaternary dating techniques. More such comparisons are needed. ?? 2007 Elsevier Ltd and INQUA.

Late Quaternary lake-level changes constrained by radiocarbon and stable isotope studies on sediment cores from Lake Titicaca, South America

NASA Astrophysics Data System (ADS)

Rowe, Harold D.; Guilderson, Thomas P.; Dunbar, Robert B.; Southon, John R.; Seltzer, Geoffrey O.; Mucciarone, David A.; Fritz, Sherilyn C.; Baker, Paul A.

2003-09-01

We present and compare AMS- 14C geochronologies for sediment cores recovered from Lake Titicaca, South America. Radiocarbon dates from three core sites constrain the timing of late Quaternary paleoenvironmental changes in the Central Andes and highlight the site-specific factors that limit the radiocarbon geochronometer. With the exception of mid-Holocene sediments, all cores are generally devoid of macrophyte fragments, thus bulk organic fractions are used to build core chronologies. Comparisons of radiocarbon results for chemically defined fractions (bulk decalcified, humate, humin) suggest that ages derived from all fractions are generally coherent in the post-13,500 yr BP time interval. In the pre-13,500 yr BP time interval, ages derived from humate extracts are significantly younger (300-7000 years) than ages from paired humin residues. Gross age incoherencies between paired humate and humin sub-fractions in pre-13,500 yr BP sediments from all core sites probably reflect the net downward migration of humates. Ages derived from bulk decalcified fractions at our shallow water (90 m) and deep water (230 m) core sites consistently fall between ages derived from humate and humin sub-fractions in the pre-13,500 yr BP interval, reflecting that the bulk decalcified fraction is predominantly a mixture of humate and humin sub-fractions. Bulk decalcified ages from the pre-13,500 yr BP interval at our intermediate depth core site (150 m) are consistently older than humate (youngest) and humin sub-fractions. This uniform, reproducible pattern can be explained by the mobilization of a relatively older organic sub-fraction during and after the re-acidification step following the alkaline treatment of the bulk sediment. The inferred existence of this 'alkali-mobile, acid-soluble' sub-fraction implies a different depositional/post-depositional history that is potentially associated with a difference in source material. While internally consistent geochronologies can be

The 3.6 ka Aniakchak tephra in the Arctic Ocean: A constraint on the Holocene radiocarbon reservoir age in the Chukchi Sea

USGS Publications Warehouse

Pearce, Christof; Varhelyi, Aron; Wastegård, Stefan; Muschitiello, Francesco; Barrientos Macho, Natalia; O'Regan, Matt; Cronin, Thomas M.; Gemery, Laura; Semiletov, Igor; Backman, Jan; Jakobsson, Martin

2017-01-01

The caldera-forming eruption of the Aniakchak volcano in the Aleutian Range on the Alaskan Peninsula at 3.6 cal kyr BP was one of the largest Holocene eruptions worldwide. The resulting ash is found as a visible sediment layer in several Alaskan sites and as a cryptotephra on Newfoundland and Greenland. This large geographic distribution, combined with the fact that the eruption is relatively well constrained in time using radiocarbon dating of lake sediments and annual layer counts in ice cores, makes it an excellent stratigraphic marker for dating and correlating mid–late Holocene sediment and paleoclimate records. This study presents the outcome of a targeted search for the Aniakchak tephra in a marine sediment core from the Arctic Ocean, namely Core SWERUS-L2-2-PC1 (2PC), raised from 57 m water depth in Herald Canyon, western Chukchi Sea. High concentrations of tephra shards, with a geochemical signature matching that of Aniakchak ash, were observed across a more than 1.5 m long sediment sequence. Since the primary input of volcanic ash is through atmospheric transport, and assuming that bioturbation can account for mixing up to ca. 10 cm of the marine sediment deposited at the coring site, the broad signal is interpreted as sustained reworking at the sediment source input. The isochron is therefore placed at the base of the sudden increase in tephra concentrations rather than at the maximum concentration. This interpretation of major reworking is strengthened by analysis of grain size distribution which points to ice rafting as an important secondary transport mechanism of volcanic ash. Combined with radiocarbon dates on mollusks in the same sediment core, the volcanic marker is used to calculate a marine radiocarbon reservoir age offset ΔR = 477 ± 60 years. This relatively high value may be explained by the major influence of typically "carbon-old" Pacific waters, and it agrees well with recent estimates of ΔR along the northwest

PREFACE: Sensors and Their Applications XVII

NASA Astrophysics Data System (ADS)

Bilas, V.; McConnell, G.; Kyriacou, P.

2013-06-01

Kyriacou Organising Committee Conference Organising Committee V Bilas, conference chair, University of Zagreb, Croatia G McConnell, conference chair, University of Strathclyde, UK P Kyriacou, conference chair, City University London, UK D Stewart, conference co-ordinator, Institute of Physics, UK Technical Programme Committee L Benini, University of Bologna, Italy M Butta, Czech Technical University in Prague, Czech Republic M Cifrek, University of Zagreb, Croatia G Collier, Kingston University London, UK J Deur, University of Zagreb, Croatia H Dzapo, University of Zagreb, Croatia M Gasulla, Universitat Politenica de Catalunya, BarcelonaTech, Spain S Hadjiloucas, University of Reading, UK P Kyriacou, City University of London, UK I Lackovic, University of Zagreb, Croatia R Magjarevic, University of Zagreb, Croatia G McConnell, University of Strathclyde, UK A O'Riordan, Tyndall National Institute, UK K Ozanyan, University of Manchester, UK A Peyton, University of Manchester, UK S Reilly, National Physical Laboratory, UK T Sun, City University London, UK A Tickle, Coventry University, UK D Vasic, University of Zagreb, Croatia S Welch, ESPKTN, UK Y Yan, University of Kent, UK H Zangl, Technical University of Graz, Austria

Landslide prediction using combined deterministic and probabilistic methods in hilly area of Mt. Medvednica in Zagreb City, Croatia

NASA Astrophysics Data System (ADS)

Wang, Chunxiang; Watanabe, Naoki; Marui, Hideaki

2013-04-01

The hilly slopes of Mt. Medvednica are stretched in the northwestern part of Zagreb City, Croatia, and extend to approximately 180km2. In this area, landslides, e.g. Kostanjek landslide and Črešnjevec landslide, have brought damage to many houses, roads, farmlands, grassland and etc. Therefore, it is necessary to predict the potential landslides and to enhance landslide inventory for hazard mitigation and security management of local society in this area. We combined deterministic method and probabilistic method to assess potential landslides including their locations, size and sliding surfaces. Firstly, this study area is divided into several slope units that have similar topographic and geological characteristics using the hydrology analysis tool in ArcGIS. Then, a GIS-based modified three-dimensional Hovland's method for slope stability analysis system is developed to identify the sliding surface and corresponding three-dimensional safety factor for each slope unit. Each sliding surface is assumed to be the lower part of each ellipsoid. The direction of inclination of the ellipsoid is considered to be the same as the main dip direction of the slope unit. The center point of the ellipsoid is randomly set to the center point of a grid cell in the slope unit. The minimum three-dimensional safety factor and corresponding critical sliding surface are also obtained for each slope unit. Thirdly, since a single value of safety factor is insufficient to evaluate the slope stability of a slope unit, the ratio of the number of calculation cases in which the three-dimensional safety factor values less than 1.0 to the total number of trial calculation is defined as the failure probability of the slope unit. If the failure probability is more than 80%, the slope unit is distinguished as 'unstable' from other slope units and the landslide hazard can be mapped for the whole study area.

The NOSAMS sample preparation laboratory in the next millenium: Progress after the WOCE program

NASA Astrophysics Data System (ADS)

Gagnon, Alan R.; McNichol, Ann P.; Donoghue, Joanne C.; Stuart, Dana R.; von Reden, Karl; Nosams

2000-10-01

Since 1991, the primary charge of the National Ocean Sciences AMS (NOSAMS) facility at the Woods Hole Oceanographic Institution has been to supply high throughput, high precision AMS 14C analyses for seawater samples collected as part of the World Ocean Circulation Experiment (WOCE). Approximately 13,000 samples taken as part of WOCE should be fully analyzed by the end of Y2K. Additional sample sources and techniques must be identified and incorporated if NOSAMS is to continue in its present operation mode. A trend in AMS today is the ability to routinely process and analyze radiocarbon samples that contain tiny amounts (<100 μg) of carbon. The capability to mass-produce small samples for 14C analysis has been recognized as a major facility goal. The installation of a new 134-position MC-SNICS ion source, which utilizes a smaller graphite target cartridge than presently used, is one step towards realizing this goal. New preparation systems constructed in the sample preparation laboratory (SPL) include an automated bank of 10 small-volume graphite reactors, an automated system to process organic carbon samples, and a multi-dimensional preparative capillary gas chromatograph (PCGC).

Determination of the Prebomb Southern (Antartic) Ocean Radiocarbon in Organic Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guilderson, T P

2001-02-26

The Southern Hemisphere is an important and unique region of the world's oceans for water-mass formation and mixing, upwelling, nutrient utilization, and carbon export. In fact, one of the primary interests of the oceanographic community is to decipher the climatic record of these processes in the source or sink terms for Southern Ocean surface waters in the CO{sub 2} balance of the atmosphere. Current coupled ocean-atmosphere modeling efforts to trace the input of CO{sub 2} into the ocean imply a strong sink of anthropogenic CO{sub 2} in the southern ocean. However, because of its relative inaccessibility and the difficulty inmore » directly measuring CO{sub 2} fluxes in the Southern Ocean, these results are controversial at best. An accepted diagnostic of the exchange of CO{sub 2} between the atmosphere and ocean is the prebomb distribution of radiocarbon in the ocean and its time-history since atmospheric nuclear testing. Such histories of {sup 14}C in the surface waters of the Southern Ocean do not currently exist, primarily because there are few continuous biological archives (e.g., in corals) such as those that have been used to monitor the {sup 14}C history of the tropics and subtropics. One of the possible long-term archives is the scallop Adamussium collbecki. Although not independently confirmed, relatively crude growth rate estimates of A. collbecki indicate that it has the potential to provide continuous 100 year time-series. We are exploring the suitability of this potential archive.« less

Mineralogy, geochemistry, and radiocarbon ages of deep sea sediments from the Gulf of Mexico, Mexico

NASA Astrophysics Data System (ADS)

Armstrong-Altrin, John S.; Machain-Castillo, María Luisa

2016-11-01

The mineralogy, geochemistry, and radiocarbon ages of two sediment cores (GMX1 and GMX2) collected from the deep sea area of the Southwestern Gulf of Mexico (∼876-1752 m water depth) were studied to infer the sedimentation rate, provenance, heavy metal contamination, and depositional environment. The sediments are dominated by silt and clay fractions. The mineralogy determined by X-Ray diffractometry for the sediment cores reveals that montmorillonite and muscovite are the dominant clay minerals. The sections between 100 and 210 cm of the sediment cores GMX1 and GMX2, respectively, are characterized by the G. menardii group and G. Inflata planktonic foraminiferal species, which represent the Holocene and Pleistocene, respectively. The radiocarbon-age measurements of mixed planktonic foraminifera varied from ∼268 to 45,738 cal. years B.P and ∼104 to 25,705 cal. years B.P, for the sediment cores GMX1 and GMX2, respectively. The variation in age between the two sediment cores is due to a change in sediment accumulation rate, which was lowest at the location GMX1 (0.006 cm/yr) and highest at the location GMX2 (0.017 cm/yr). The chemical index of alteration (CIA), chemical index of weathering (CIW), and index of chemical maturity (ICV) values indicated a moderate intensity of weathering in the source area. The total rare earth element concentrations (∑REE) in the cores GMX1 and GMX2 vary from ∼94 to 171 and ∼78 to 151, respectively. The North American Shale Composite (NASC) normalized REE patterns showed flat low REE (LREE), heavy REE (HREE) depletion with low negative to positive Eu anomalies, which suggested that the sediments were likely derived from intermediate source rocks. The enrichment factor of heavy metals indicated that the Cd and Zn concentrations in the sediment cores were impacted by an anthropogenic source. The redox-proxy trace element ratios such as V/Cr, Ni/Co, Cu/Zn, (Cu + Mo)/Zn, and Ce/Ce* indicated that the sediments were deposited

Database of Alluvial Radiocarbon Dates in European Russia and Siberia and its Palaeohydrological Interpretation

NASA Astrophysics Data System (ADS)

Matlakhova, Ekaterina; Panin, Andrei

2017-04-01

We collected and analyzed published radiocarbon dates from East European Plain (EEP) and Siberia to pick absolute dates on alluvial and associated deposits. After filtering unreliable dates, 1000 radiocarbon dates from EEP and 500 from Siberia were included into the database. Each date was supplied with information on geographic location and coordinates, catchment area, geomorphological position, characteristics of geological section and dated materials. Also the information about published sources was given. Documented sections refer to fluvial forms in a wide range of catchment sizes. To extract palaeohydrological signal we used two kinds of proxies: sedimentological and geomorphological. We used the following indicators of low activity: organic horizons (soil, peat) in overbank alluvium, balka bottoms and gully fans, small river palaeochannels; and the following indicators of high activity: active sedimentation on river floodplains (burial of organic horizons), balka bottoms and gully fans, erosion by flood flows on floodplains, in bottoms of balkas and gullies, river incision, big palaeochannels, channel avulsions and chute cutoffs. 
 Each date that received palaeohydrological interpretation was regarded as the indicator of a particular Local Palaeohydrological Event. Combined probability density functions of high- and low-activity dates were used to detect time intervals of different palaeohydrological status. For EEP after low fluvial activity during LGM two palaeohydrological epochs were designated: extremely high activity in the end of MIS 2 (ca. 18-11.7 ka b2k), and much lower activity in the Holocene. Within the Holocene two hierarchical levels of hydroclimatic variability were designated according to their duration and magnitude - regional palaeohydrological phases (centuries to few millennia) and regional palaeofluvial episodes (decades to few centuries). Tendency is rather clear of activity lowering in the first half and rise in the second half of

Radiocarbon Based Ages and Growth Rates: Hawaiian Deep Sea Corals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roark, E B; Guilderson, T P; Dunbar, R B

2006-01-13

The radial growth rates and ages of three different groups of Hawaiian deep-sea 'corals' were determined using radiocarbon measurements. Specimens of Corallium secundum, Gerardia sp., and Leiopathes glaberrima, were collected from 450 {+-} 40 m at the Makapuu deep-sea coral bed using a submersible (PISCES V). Specimens of Antipathes dichotoma were collected at 50 m off Lahaina, Maui. The primary source of carbon to the calcitic C. secundum skeleton is in situ dissolved inorganic carbon (DIC). Using bomb {sup 14}C time markers we calculate radial growth rates of {approx} 170 {micro}m y{sup -1} and ages of 68-75 years on specimensmore » as tall as 28 cm of C. secundum. Gerardia sp., A. dichotoma, and L. glaberrima have proteinaceous skeletons and labile particulate organic carbon (POC) is their primary source of architectural carbon. Using {sup 14}C we calculate a radial growth rate of 15 {micro}m y{sup -1} and an age of 807 {+-} 30 years for a live collected Gerardia sp., showing that these organisms are extremely long lived. Inner and outer {sup 14}C measurements on four sub-fossil Gerardia spp. samples produce similar growth rate estimates (range 14-45 {micro}m y{sup -1}) and ages (range 450-2742 years) as observed for the live collected sample. Similarly, with a growth rate of < 10 {micro}m y{sup -1} and an age of {approx}2377 years, L. glaberrima at the Makapuu coral bed, is also extremely long lived. In contrast, the shallow-collected A. dichotoma samples yield growth rates ranging from 130 to 1,140 {micro}m y{sup -1}. These results show that Hawaiian deep-sea corals grow more slowly and are older than previously thought.« less

Language Politics in Bosnia, Croatia, and Serbia

DTIC Science & Technology

2010-03-01

Toward a Common Standard ( Zagreb , Croatia: Globus, 1995), 14. 8 Alexander, Bosnian, Croatian, Serbian, 380–381. 9 Stanley G. Evans, A Short History...Yugoslav Academy of Sciences and Arts in Zagreb in 1867. The Yugoslav Academy contained the first institution concerned with south Slavic languages...northern Croatia, especially in the Zagreb area, and Čakavian is spoken along the Adriatic coast in Dalmatia and on the Istrian peninsula.33 Another

Corruption in the Balkans: An Examination of the Ties Between Government and Crime in Several Southeast European Countries

DTIC Science & Technology

2013-12-01

Mataković, Transparency in Funding Political Parties: Croatia 2011 ( Zagreb : Transparency International Croatia, 2011), 7, 19; Stevan Dojčinović et al...compulsory measures that could have forced Zagreb to further reduce its corruption have now been removed. Despite many recent steps in the right...authorities discovered the body of Ivana Hodak, the daughter of a recognized prosecutor in Zagreb , in the stairwell outside her apartment building

Who Is Guarding Serbia’s Borders? An Assessment of Serbia’s Progress in Border Security Development and Reform

DTIC Science & Technology

2011-06-01

For example, in 2009 the British embassies in Zagreb and Belgrade funded a project to have the International Organization for Migration (IOM) utilize...Embassy Zagreb , UK in Croatia, “UK-backed Croatia-Serbia border police project successfully completed,” (3 May 2010), accessed May 17, 2010, http...cocaine seizure was made and two people arrested at Zagreb airport bound for Serbia. Also in November 2009, Serbian police arrested four people in

The Bosnian Train and Equip Program: A Lesson in Interagency Integration of Hard and Soft Power

DTIC Science & Technology

2014-03-01

first week of January, 1996. In Zagreb , the Croatians were cautiously supportive on the condition that the program would be administered through the...and rail. That required support from Croatian officials in Zagreb to use the Croatian port of Ploce, which controlled the most efficient means of...the major impediment to passing the Defense Law and appealed to authorities in Zagreb to encourage their cooperation.199 Yet they also thought the

Estimates of upwelling rates in the Arabian Sea and the equatorial Indian Ocean based on bomb radiocarbon.

PubMed

Bhushan, R; Dutta, K; Somayajulu, B L K

2008-10-01

Radiocarbon measurements were made in the water column of the Arabian Sea and the equatorial Indian Ocean during 1994, 1995 and 1997 to assess the temporal variations in bomb 14C distribution and its inventory in the region with respect to GEOSECS measurements made during 1977-1978. Four GEOSECS stations were reoccupied (three in the Arabian Sea and one in the equatorial Indian Ocean) during this study, with all of them showing increased penetration of bomb 14C along with decrease in its surface water activity. The upwelling rates derived by model simulation of bomb 14C depth profile using the calculated exchange rates ranged from 3 to 9 m a(-1). The western region of the Arabian Sea experiencing high wind-induced upwelling has higher estimated upwelling rates. However, lower upwelling rates obtained for the stations occupied during this study could be due to reduced 14C gradient compared to that during GEOSECS.

Sensitivity of simulated deep ocean natural radiocarbon to gas exchange velocity and historical atmospheric Δ14C variations

NASA Astrophysics Data System (ADS)

Wagner, Hannes; Koeve, Wolfgang; Kriest, Iris; Oschlies, Andreas

2015-04-01

Simulated deep ocean natural radiocarbon is frequently used to assess model performance of deep ocean ventilation in Ocean General Circulation Models (OGCMs). It has been shown to be sensitive to a variety of model parameters, such as the mixing parameterization, convection scheme and vertical resolution. Here we use three different ocean models (MIT2.8, ECCO, UVic) to evaluate the sensitivity of simulated deep ocean natural radiocarbon to two other factors, while keeping the model physics constant: (1) the gas exchange velocity and (2) historic variations in atmospheric Δ^1^4C boundary conditions. We find that simulated natural Δ^1^4C decreases by 14-20 ‰ throughout the deep ocean and consistently in all three models, if the gas exchange velocity is lowered by 30 % with respect to the OCMIP-2 protocol, to become more consistent with newer estimates of the oceans uptake of bomb derived ^1^4C. Simulated deep ocean natural Δ^1^4C furthermore decreases by 3-9 ‰ throughout the deep Pacific, Indian and Southern Oceans and consistently in all three models, if the models are forced with the observed atmospheric Δ^1^4C history, instead of an often made pragmatic assumption of a constant atmospheric Δ^1^4C value of zero. Applying both improvements (gas exchange reduction, as well as atmospheric Δ^1^4C history implementation) concomitantly and accounting for the present uncertainty in gas exchange velocity estimates (between 10 and 40 % reduction with respect to the OCMIP-2 protocol) simulated deep ocean Δ^1^4C decreases by 10-30 ‰ throughout the deep Pacific, Indian and Southern Ocean. This translates to a ^1^4C-age increase of 100-300 years and indicates, that models, which in former assessments (based on the OCMIP-2 protocol) had been identified to have an accurate deep ocean ventilation, should now be regarded as rather having a bit too sluggish a ventilation. Models, which on the other hand had been identified to have a bit too fast a deep ocean ventilation

Radiocarbon-based carbon source quantification of anomalous isotopic foraminifera in last glacial sediments in the western North Pacific

NASA Astrophysics Data System (ADS)

Uchida, Masao; Ohkushi, Ken'ichi; Kimoto, Katsunori; Inagaki, Fumio; Ishimura, Toyoho; Tsunogai, Urumu; Tuzino, Taqumi; Shibata, Yasuyuki

2008-04-01

A previous study interpreted extremely 13C-depleted excursions of planktonic and benthic foraminifera in last glacial sediments (17,500 to 25,400 cal years B.P.) of the core retrieved from off Shimokita Peninsula and off Hokkaido, Japan, as evidence for periodic releases of methane, arising from the dissociation of methane hydrate. To better understand the formation process of the 13C-depleted excursions, we conducted high-resolution natural radiocarbon measurements and biogeochemical analyses. We found highly depleted 13C excursions ranging from -10.2‰ to -1.6‰ and -6.8‰ to -1.6‰ in planktonic and benthic foraminifera, respectively. Most of the foraminiferal tests in these horizons were brown, most likely as a result of postdepositional alteration, reflecting the formation of authigenic carbonate on the surface of tests. These alterations were also supported by high levels of Mg-calcite and the acid-leaching test for anomalous foraminifera. To evaluate the carbon sources in the altered foraminifera tests, we quantified the relative contributions of 14C-free methane-derived carbon sources to the formation of authigenic carbonates in foraminifera with depleted 13C excursions using a coupled mass balance isotopic model (14C/C and 13C/12C). The radiocarbon ages of both planktonic and benthic 13C-depleted foraminifera were approximately 600 to 2000 years older than those of normal tests from nearby horizons. The relative contributions of authigenic carbonates derived from the methane oxidizing process reached to ˜22 wt% for planktonic foraminifera and ˜15 wt% for benthic foraminifera. The δ13C values of methane calculated from the mass balance model were between -29‰ and -68‰ for planktonic foraminifera and between -40‰ and -108‰ for benthic foraminifera, consistent with δ13C values reported for thermogenic and abiogenic methane in global methane hydrate reservoirs. These data consistently suggest that methane-related drastic environmental change

Addressing the military gap in the western Balkans and closing the gap through regional cooperation

DTIC Science & Technology

2017-06-09

service so they use the services in Zagreb and Beograd.140 Croatia Based on Jane’s assessment (census in 2011), the Croatian population was estimated at...Another significant capability in the CAF is the Air Force and air defense system. The headquarters is in Zagreb and they provide control authority...New recruits and specialists are trained at the Naval Training Centre in Split (an integral part of the Croatian Military Academy [CMA] in Zagreb

Return of the Balkans: Challenges to European Integration and U.S. Disengagement

DTIC Science & Technology

2013-05-01

Zagreb than Sarajevo. The educational systems are separated, and there is no daily interaction between citizens in the two entities. This leaves young...generally supportive of the HDZ in an effort to protect Bosnian Croat inter- ests, and Zagreb was dismayed by the HDZ’s exclu- sion from the Federation...and Zagreb may coordinate a military response against attempts at RS secession, especially if Banja Luka is backed by Belgrade. For several years

Impact of the 20th Century War on Democratic Serbia Today

DTIC Science & Technology

2012-03-21

Zagreb . On April 12th, they entered Belgrade by simultaneous attacks from Bulgaria, Romania, and Austria, and by April 17th, Yugoslavia had capitulated...and it was in Zagreb that preparation for cultural assimilation, persecution and ethnic cleansing occurred.59 Hitler did not want the Balkans as... Zagreb , but Ustaša and German pressure forced him to move into Serbian territory, nearby Belgrade. This move brought Tito into conflict with Mihailović

Democratization in the Arab World: Prospects and Lessons from Around the Globe

DTIC Science & Technology

2012-01-01

Zagreb : Konrad-Adenauer-Stiftung, 2007. Egyptian Decision and Information Support Center The Role of Religion in Egyptian Society, June 2011 (in Arabic...in V. Dvořáková and A. Milardović, eds., Lustration and Consolidation of Democracy and the Rule of Law in Central and Eastern Europe, Zagreb ...Lustration and Consolidation of Democracy and the Rule of Law in Central and Eastern Europe, Zagreb : Konrad-Adenauer-Stiftung, 2007. Pew Research

Preparative separation of underivatized amino acids for compound-specific stable isotope analysis and radiocarbon dating of hydrolyzed bone collagen.

PubMed

Tripp, Jennifer A; McCullagh, James S O; Hedges, Robert E M

2006-01-01

Analysis of stable and radioactive isotopes from bone collagen provides useful information to archaeologists about the origin and age of bone artifacts. Isolation and analysis of single amino acids from the proteins can provide additional and more accurate information by removing contamination and separating a bulk isotope signal into its constituent parts. In this paper, we report a new method for the separation and isolation of underivatized amino acids from bone collagen, and their analysis by isotope ratio MS and accelerator MS. RP chromatography is used to separate the amino acids with nonpolar side chains, followed by an ion pair separation to isolate the remaining amino acids. The method produces single amino acids with little or no contamination from the separation process and allows for the measurement of accurate stable isotope ratios and pure samples for radiocarbon dating.

Sun, Ocean, Nuclear Bombs, and Fossil Fuels: Radiocarbon Variations and Implications for High-Resolution Dating

NASA Astrophysics Data System (ADS)

Dutta, Koushik

2016-06-01

Radiocarbon, or 14C, is a radiometric dating method ideally suited for providing a chronological framework in archaeology and geosciences for timescales spanning the last 50,000 years. 14C is easily detectable in most common natural organic materials and has a half-life (5,730±40 years) relevant to these timescales. 14C produced from large-scale detonations of nuclear bombs between the 1950s and the early 1960s can be used for dating modern organic materials formed after the 1950s. Often these studies demand high-resolution chronology to resolve ages within a few decades to less than a few years. Despite developments in modern, high-precision 14C analytical methods, the applicability of 14C in high-resolution chronology is limited by short-term variations in atmospheric 14C in the past. This article reviews the roles of the principal natural drivers (e.g., solar magnetic activity and ocean circulation) and the anthropogenic perturbations (e.g., fossil fuel CO2 and 14C from nuclear and thermonuclear bombs) that are responsible for short-term 14C variations in the environment. Methods and challenges of high-resolution 14C dating are discussed.