Testing against stochastic trend and seasonality in the presence of unattended breaks and unit roots

This paper considers the problem of testing against stochastic trend and seasonality in the presence of structural breaks and unit roots at frequencies other than those directly under test, which we term unattended breaks and unattended unit roots respectively. We show that under unattended breaks the true size of the Kwiatkowski et. al. (1992) [KPSS] test at frequency zero and the Canova and Hansen (1995) [CH] test at the seasonal frequencies fall well below the nominal level under the null with an associated, often very dramatic, loss of power under the alternative. We demonstrate that a simple modification of the statistics can recover the usual limiting distribution appropriate to the case where there are no breaks, provided unit roots do not exist at any of the unattended frequencies. Where unattended unit roots occur we show that the above statistics converge in probability to zero under the null. However, computing the KPSS and CH statistics after pre-filtering the data is simultaneously efficacious against both unattended breaks and unattended unit roots, in the sense that the statistics retain their usual pivotal limiting null distributions appropriate to the case where neither occurs. The case where breaks may potentially occur at all frequencies is also discussed. The practical relevance of the theoretical contribution of the paper is illustrated through a number of empirical examples.stationarity tests, structural breaks, pre-filtering, unattended unit roots

Common faith or parting ways? A time varying parameters factor analysis of euro-area inflation

We analyze the interaction among the common and country specific components for the inflation rates in twelve euro area countries through a factor model with time varying parameters. The variation of the model parameters is driven by the score of the predictive likelihood, so that, conditionally on past data, the model is Gaussian and the likelihood function can be evaluated using the Kalman filter. The empirical analysis uncovers significant variation over time in the model parameters. We find that, over an extended time period, inflation persistence has fallen over time and the importance of common shocks has increased relatively to the idiosyncratic disturbances. According to the model, the fall in inflation observed since the sovereign debt crisis, is broadly a common phenomenon, since no significant cross country inflation differentials have emerged. Stressed countries, however, have been hit by unusually large shocks

Testing stock market convergence: a non-linear factor approach

This paper applies the Phillips and Sul (Econometrica 75(6):1771–1855, 2007) method to test for convergence in stock returns to an extensive dataset including monthly stock price indices for five EU countries (Germany, France, the Netherlands, Ireland and the UK) as well as the US between 1973 and 2008. We carry out the analysis on both sectors and individual industries within sectors. As a first step, we use the Stock and Watson (J Am Stat Assoc 93(441):349–358, 1998) procedure to filter the data in order to extract the long-run component of the series; then, following Phillips and Sul (Econometrica 75(6):1771–1855, 2007), we estimate the relative transition parameters. In the case of sectoral indices we find convergence in the middle of the sample period, followed by divergence, and detect four (two large and two small) clusters. The analysis at a disaggregate, industry level again points to convergence in the middle of the sample, and subsequent divergence, but a much larger number of clusters is now found. Splitting the cross-section into two subgroups including euro area countries, the UK and the US respectively, provides evidence of a global convergence/divergence process not obviously influenced by EU policies

The 10 Meter South Pole Telescope

The South Pole Telescope (SPT) is a 10 m diameter, wide-field, offset Gregorian telescope with a 966-pixel, multi-color, millimeter-wave, bolometer camera. It is located at the Amundsen-Scott South Pole station in Antarctica. The design of the SPT emphasizes careful control of spillover and scattering, to minimize noise and false signals due to ground pickup. The key initial project is a large-area survey at wavelengths of 3, 2 and 1.3 mm, to detect clusters of galaxies via the Sunyaev-Zeldovich effect and to measure the small-scale angular power spectrum of the cosmic microwave background (CMB). The data will be used to characterize the primordial matter power spectrum and to place constraints on the equation of state of dark energy. A second-generation camera will measure the polarization of the CMB, potentially leading to constraints on the neutrino mass and the energy scale of inflation.Comment: 47 pages, 14 figures, updated to match version to be published in PASP 123 903 (May, 2011

Gypsum Dissolution Rate, New Data and Insights

Sinkholes linked to covered evaporite karst in urban environments still represent a challenge in hazard and risk assessment. The Quinis hamlet, located in Friuli Venezia Giulia region (NE Italy), is heavily affected by sinkhole phenomena (linked to an evaporitic bedrock), which deeply interested infrastructures and houses. In order to understand the evolution of the sinking phenomena, a field experiment started on the dissolution rate of the gypsum. In 17 existing piezometers, at different depths, 51 evaporitic rock samples were exposed to the naturally occurring variation of relative humidity, air flow and hydrodynamics. The rock samples were placed respectively in the aeration, in the fluctuation and in the phreatic section of the piezometric tubes. Data related to groundwater level fluctuations, temperature and electrical conductivity were collected. After four months, rock samples were removed, weighted and the volume loss evaluated. The obtained results indicate that rock sample reduction is not only dependent on the groundwater level fluctuations and on the number of days during which the samples are immersed in the groundwaters but also on the mineralization of the latter. Some of the rock samples have been almost completely dissolved, with dissolution rate values almost eight times bigger than expected if compared to the available literature data. The proposed approach had as aim to evaluate the quickness of the dissolution process, which is dependant on several causes (groundwater level fluctuations, type of rocks, chemical characteristics of the groundwaters, etc.) and represents a novel contribution to the overall knowledge of karst processes with noticeable impacts on human-built construction

Non-invasive methodological approach to detect and characterize high-risk sinkholes in urban cover evaporite karst: Integrated reflection seismics, PS-INSAR, leveling, 3D-GPR and ancillary data. a Ne Italian case study

Sinkholes linked to cover evaporite karst in urban environments still represent a challenge in terms of their clear identification and mapping considering the rehash and man-made structures. In the present research, we have proposed and tested a methodology to identify the subsiding features through an integrated and non-invasive multi-scale approach combining seismic reflection, PS-InSAR (PSI), leveling and full 3D Ground Penetrating Radar (GPR), and thus overpassing the limits of each method. The analysis was conducted in a small village in the Alta Val Tagliamento Valley (Friuli Venezia Giulia region, NE Italy). Here, sinkholes have been reported for a long time as well as the hazards linked to their presence. Within past years, several houses have been demolished and at present many of them are damaged. The PSI investigation allowed the identification of an area with higher vertical velocities; seismic reflection imagined the covered karst bedrock, identifying three depocenters; leveling data presented a downward displacement comparable with PSI results; 3D GPR, applied here for the first time in the study and characterization of sinkholes, defined shallow sinking features. Combining all the obtained results with accurate field observations, we identified and mapped the highest vulnerable zone

Coastal Storm-Induced Sinkholes: Insights from Unmanned Aerial Vehicle Monitoring

In recent decades, the scientific community has increasingly focused on extreme events linked to climate change, which are leading to more intense and frequent natural disasters. The Mediterranean can be considered a hotspot where the effects of these changes are expected to be more intense compared to other regions of the planet. Italy is not exempt; in fact, with its extensive shoreline, it is particularly vulnerable, especially to high sea levels and coastal erosions. In this framework, from late October to early November 2023, six storm surges occurred in the Gulf of Trieste (NE Italy). These events, characterized by winds from 190°N to 220°N and the significant wave height, which reached up to 1.81 m nearshore—an uncommon meteorological condition in the northern Adriatic Sea—caused the occurrence of eight coastal sinkholes and substantial damages to man-made structures. Thanks to Unmanned Aerial Vehicles (UAVs) and their derived products (high-resolution orthomosaics, Digital Elevation Models—DEMs, and point clouds), it was possible to study these features over time, enabling long-term coastal dynamics monitoring, which can be crucial for timely and effective response and restoration efforts

Predictors of choice of initial antifungal treatment in intraabdominal candidiasis

Intraabdominal candidiasis (IAC) is the second most frequent form of invasive candidiasis, and is associated with high mortality rates. This study aims to identify current practices in initial antifungal treatment (IAT) in a real-world scenario and to define the predictors of the choice of echinocandins or azoles in IAC episodes. Secondary analysis was performed of a multinational retrospective cohort at 13 teaching hospitals in four countries (Italy, Greece, Spain and Brazil), over a 3-year period (2011\u20132013). IAC was identified in 481 patients, 323 of whom received antifungal therapy (classified as the treatment group). After excluding 13 patients given amphotericin B, the treatment group was further divided into the echinocandin group (209 patients; 64.7%) and the azole group (101 patients; 32.3%). Median APACHE II scores were significantly higher in the echinocandin group (p 0.013), but IAT did not differ significantly with regard to the Candida species involved. Logistic multivariate stepwise regression analysis, adjusted for centre effect, identified septic shock (adjusted OR (aOR) 1.54), APACHE II > 15 (aOR 1.16) and presence in surgical ward at diagnosis (aOR 1.16) as the top three independent variables associated with an empirical echinocandin regimen. No differences in 30-day mortality were observed between groups. Echinocandin regimen was the first choice for IAT in patients with IAC. No statistical differences in mortality were observed between regimens, but echinocandins were administered to patients with more severe disease. Some disagreements were identified between current clinical guidelines and prescription of antifungals for IAC at the bedside, so further educational measures are required to optimize therapies

Characterization of an onshore–offshore aquifer system in the Venetian Friulian Plain and north Adriatic Basin: a 3D modeling approach

Continental coastal aquifer systems are well-studied worldwide and are often characterized on the basis of extensive and diverse borehole datasets. However, while it is postulated that in some cases, these aquifers may extend offshore, their seaward reach remains widely unknown due to the frequently limited availability of data, particularly for subsurface sediments and their pore water salinity. This paper presents a valuable characterization of the onshore aquifers in the Venetian-Friulian Plain (northeastern Italy) and their offshore extension in the Northern Adriatic Shelf, within ~20 km from the coastline. Three-dimensional digital geological and stratigraphic modeling was used to investigate geometries of the layered artesian aquifer system hosted in the Middle to Late Pleistocene sedimentary succession. Near-coastal and offshore aquifers are found to have mainly formed during coastline migration driven by sea level changes and low-permeability layers, sealing these aquifers, result from fine alluvial sediments during sea level lowstands or fine marine sediments during highstands. This study suggests that Quaternary glacio-eustatic fluctuations are mainly responsible for the genesis of the layered aquifer system in the study area. Given the consistency of depositional processes active in the Northern Adriatic Basin since Middle-Pleistocene, and that coastal fresh groundwater extends hundreds of meters below the topographic surface, this study confirms that the Northern Adriatic Basin has significant potential to host widespread offshore freshened groundwater aquifers. This resource might represent an additional freshwater supply in the future

Behaviour and fate of nine recycled water trace organics during managed aquifer recharge in an aerobic aquifer

The fate of nine trace organic compounds was evaluated during a 12 month large-scale laboratory column experiment. The columns were packed with aquifer sediment and evaluated under natural aerobic and artificial anaerobic geochemical conditions, to assess the potential for natural attenuation of these compounds during aquifer passage associated with managed aquifer recharge (MAR). The nine trace organic compounds were bisphenol A (BPA), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMOR), carbamazepine, oxazepam, iohexol and iodipamide. In the loworganic carbon content Spearwood sediment, all trace organicswere non-retardedwith retardation coefficients between 1.0 and 1.2, indicating that these compounds would travel at near groundwater velocities within the aquifer. The natural aerobic geochemical conditions provided a suitable environment for the rapid degradation for BPA, E2, iohexol (half life b1 day). Lag-times for the start of degradation of these compounds ranged from b15 to 30 days. While iodipamide was persistent under aerobic conditions, artificial reductive geochemical conditions promoted via the addition of ethanol, resulted in rapid degradation (half life b1 days). Pharmaceuticals (carbamazepine and oxazepam) and disinfection by-products (NDMA and NMOR) did not degrade under either aerobic or anaerobic aquifer geochemical conditions (half life N50 days). Field-based validation experiments with carbamazepine and oxazepam also showed no degradation. If persistent trace organics are present in recycled waters at concentrations in excess of their intended use, natural attenuation during aquifer passage alonemay not result in extracted watermeeting regulatory requirements. Additional pre treatment of the recycled water would therefore be required