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The Centre for Dating and Diagnostics was established in 2001 at the University of Salento with the aim of becoming a National Centre for radiocarbon dating by AMS. After more than fifteen years of operation this goal has been fully achieved with thousands of dated samples for researches spanning from Archaeological, Earth and Forensics sciences to industrial and environmental applications. Furthermore, in the frame of different large scale National projects, the experimental potential of the facility has been substantially improved through the installation of new beam lines and experimental set-ups.

The Capitoline she wolf is a Bronze statue located at the “Capitoline Museums” in Rome, Italy. The extraordinary cultural and symbolic importance of the statue is mainly related to the myth of the Capitoline she wolf and to the legendary origin of the city of Rome. Though traditionally considered an Etruscan bronze, recently a much more recent age was suggested on the base of consideration related to the used casting technique. In this paper we present the results of an AMS radiocarbon dating campaign carried out on the organic residues found in the casting cores recovered from the inner part of the statue. The obtained results firmly anchor the statue to the XI-XII centuries CE, in the Middle Ages.

The determination of the age of elephant ivory is a crucial aspect in the fight against illegal ivory trade which is still a relevant problem having triggered the decline of elephant populations due to poaching in different areas of the globe. Indeed, the absolute dating of the ivory allows, in forensics practice, to establish whether a determined sample or object was obtained and imported illegally, violating the international trade ban. In this frame the use radiocarbon dating has surely a great potential and is widely used. In this paper we review the potential of the method in this field, highlighting its advantages and drawbacks. In particular we show, through the discussion of real cases, how it is possible to improve the achievable chronological resolution by refining the obtained ages trough the proper use of available information and considerations.

A new sputtering ion source has been installed at CEDAD (Centre for Dating and Diagnostics) at the University of Salento in Lecce, Italy. The installation of the new ion source, capable of accepting both solid and gas samples, required significant modifications of the existing low energy injector of the accelerator mass spectrometry (AMS) system. The new ion source is connected, through an in-house designed gas handling interface, to an elemental analyzer which combusts the samples to carbon dioxide and splits the gas into an IRMS system and also to the gas feed line of the ion source. This arrangement allows the simultaneous measurement of C, N content (in the EA), carbon and nitrogen stable isotopic ratios by IRMS and radiocarbon (14C) by AMS on samples with masses in the microgram range. The results of different tests performed to find optimal operational conditions and to improve the system performances are presented. The performances of the system as a function of the diameter of the glass capillary used to feed the source and the pressure of the gas mixture in the syringe are also presented. The achievable precision and blank levels are discussed together with the results obtained in environmental studies.

Parabens and phenoxyethanol are chemical compounds widely used as preservatives and antimicrobial agents in cosmetic and personal care products. The issue of their effect on human and environmental health is a particularly topical and relevant one that many national and international agencies reported about the risk from the use of such compounds. In the present paper, iron doped TiO2 nanoparticles were synthetized and characterized by morphological and spectroscopic techniques. The proposed synthesis was designed to improve the photocatalytic activity of the nanostructures towards the two preservatives compounds when irradiated by a visible light, in order to optimize the effect of natural irradiation on the photodegradation of the two compounds. Preliminary photocatalytic tests showed that the analytes’ concentration in water solutions under illumination in presence of both iron-doped TiO2 and pure TiO2 decreased. A sensible enhancement of photocatalysis of both propylparaben and phenoxyethanol was recorded in presence of the Fe-doped nanostructures as a consequence of the physical and chemical properties of the catalyst.

In this paper, we present the results of the accelerator mass spectrometry radiocarbon (AMS14C) dating campaign performed on samples selected from different levels in Grotta Romanelli (Castro, Italy). Grotta Romanelli is one of the key sites for the chronology of Middle Pleistocene–Holocene in Mediterranean region. After the first excavation campaigns carried out in the first decades of the 1900s, the cave has been systematically re-excavated only since 2015. During the last excavation campaigns different faunal remains were selected and submitted for 14C dating in order to confirm the chronology of the cave with a higher resolution. Isotopic ratio mass spectrometry (IRMS) measurements were also carried out on faunal remains.

A new type of “speleothem” was recently found and described in submarine caves along the Southern coast of the Adriatic Sea in Italy. Previous studies demonstrated the fully biogenic and submarine origin of these structures which appeared to be formed by calcareous tubules of worms, embedded in a much finer texture matrix. AMS radiocarbon dating analyses allowed the determination of the age of these structures and to study the temporal evolution of their growth rate. In this paper, we report new dates obtained on the matrix around the already dated core tubules. Compositional analyses demonstrated that the matrix is mainly formed by calcium carbonate and AMS radiocarbon age measurements performed at CEDAD suggest its biogenic origin. Absolute ages on the matrix are statistically consistent internally and with the calcareous tubules. The obtained results are highly complementary to other studies being performed in order to identify the biological processes governing the formation and growth of these structures.

We propose a scalar variation of the multivariate HEAVY model of Noureldin et al. (2012) featuring a time-varying long run (co)volatility component coupled with DCC dynamics. The new model outperforms the original HEAVY model by delivering more accurate multi-step-ahead predictions.

A new experimental set-up dedicated to the simultaneous measurements of stable carbon and nitrogen isotopic ratios by IRMS (Isotope Ratio Mass Spectrometry) and 14C by AMS (Accelerator Mass Spectrometry) has been installed at CEDAD (Centre for Dating and Diagnostics)-University of Salento. The new set-up is formed by different functional blocks: an elemental analyzer, an IRMS spectrometer, a gas handling unit and a new hybrid sputtering ion source, connected to the AMS system. The general features of the new system are presented as well as the technical solutions adopted for its integration with the existing AMS system. Different tests were performed by analyzing samples of known isotopic composition and of different masses in order to define optimal operating conditions. In particular it is shown how radiocarbon measurements with precision of 0.6–0.7% and 1% are possible with the new system on samples of mass of the order of ∼20 μg and ∼10 μg, respectively. Background levels of the order of 10−14 (14C/12C) have been also demonstrated. The new system has then significantly extended the experimental potential of the Centre in several research fields where the possibility to date very low mass samples is either a crucial advantage or mandatory such as in environmental sciences and cultural heritage dating.

A dedicated sample processing line for the extraction of dissolved inorganic carbon (DIC) from seawater and groundwater for accelerator mass spectrometry (AMS) radiocarbon analysis has been developed at CEDAD, the Center for Dating and Diagnostic of the University of Salento, Lecce, Italy. The features of the new system are presented together with tests carried out to determine its functionality and background levels. The first results obtained at CEDAD for analyzing seawater samples taken from the Northern Adriatic compare well with results obtained for the same samples analyzed at ETH Zurich. DOI: 10.2458/azu_js_rc.55.16268

The Multiplicative MIDAS Realized DCC (MMReDCC) model simultaneously accounts for short and long term dynamics in the conditional (co)volatilities of asset returns, in line with the empirical evidence suggesting that their level is changing over time as a function of economic conditions. Herein the applicability of the model is improved along two directions. First, by proposing an algorithm that relies on the maximization of an iteratively re-computed moment-based profile likelihood function and keeps estimation feasible in large dimensions by mitigating the incidental parameter problem. Second, by illustrating a conditional bootstrap procedure to generate multi-step ahead predictions from the model. In an empirical application on a dataset of forty-six equities, the MMReDCC model is found to statistically outperform the selected benchmarks in terms of in-sample fit as well as in terms of out-of-sample covariance predictions. The latter are mostly significant in periods of high market volatility.

Archaeological surface surveys carried out near Salve in southern Italy led to the identification of about 90 stone mounds spread over an area of about 100 ha. Systematic archaeological investigations allowed to identify the mounds as funeral structures with some having megalithic features. In the necropolis, both the inhumation and cremation rituals are evident, in some cases within the same mound. This article presents the results of an accelerator mass spectrometry (AMS) radiocarbon dating campaign carried out on different kinds of samples recovered from several structures: unburned and cremated bones, charcoals, and organic residues extracted from pottery sherds. The results allowed to assess the chronology of the site and to shed new light on the different funeral practices in Copper Age southern Italy. DOI: 10.2458/56.17887

Financial asset returns are known to be conditionally heteroskedastic and generally non-normally distributed, fat-tailed and often skewed. These features must be taken into account to produce accurate forecasts of Value-at-Risk (VaR). We provide a comprehensive look at the problem by considering the impact that different distributional assumptions have on the accuracy of both univariate and multivariate GARCH models in out-of-sample VaR prediction. The set of analyzed distributions comprises the normal, Student, Multivariate Exponential Power and their corresponding skewed counterparts. The accuracy of the VaR forecasts is assessed by implementing standard statistical backtesting procedures used to rank the different specifications. The results show the importance of allowing for heavy-tails and skewness in the distributional assumption with the skew-Student outperforming the others across all tests and confidence levels.

Accelerator mass spectrometry (AMS) radiocarbon analyses were performed on biobased unsaturated polyester resins in order to assess the potential of the method for the determination of the bio-fraction. Different resins were synthesized in the laboratory with different proportions of raw materials of biogenic origin, and analyzed both in the liquid and in the solid form. As a preliminary step of the study, both the biobased and the fossil-derived raw materials were analyzed in order to determine their 14C content. A comparison of the obtained results with the expected ones allowed us to investigate the potential of the 14C method in this field as well as to address some still open issues such as the levels of uncertainty and accuracy as related to the calculation procedures, the correction for isotopic fractionation, and the effect of the presence of volatile components in the analyzed materials.

Automatic test generators pursue some type of systematic coverage of the program code or heuristic sampling of the program inputs. Test generators are effective after the assumption, often (enthusiastically) embraced by researchers, that the generated test cases produce informative data for domain experts, e.g., pinpoint important bugs. This paper investigates the validity of such assumption through a case study of using test generators on industrial software with nontrivial domain-specific peculiarities. Our results properly enhance the available body of knowledge on the strengths and weaknesses of test generators.

Novel model specifications that include a time-varying long run component in the dynamics of realized covariance matrices are proposed. The adopted modeling framework allows the secular component to enter the model structure either in an additive fashion or as a multiplicative factor, and to be specified parametrically, using a MIDAS filter, or non-parametrically. Estimation is performed by maximizing a Wishart quasi-likelihood function. The one-step ahead forecasting performance of the models is assessed by means of three approaches: the Model Confidence Set, (global) minimum variance portfolios and Value-at-Risk. The results provide evidence in favour of the hypothesis that the proposed models outperform benchmarks incorporating a constant long run component, both in and out-of sample.