A time-dependent extension of the projected normal regression model for longitudinal circular data based on a hidden Markov heterogeneity structure

The modelling of animal movement is an important ecological and environmental issue. It is well-known that animals change their movement patterns over time, according to observable and unobservable factors. To trace the dynamics of behaviors, to identify factors influencing these dynamics and unobserved characteristics driving intra-subjects correlations, we introduce a time-dependent mixed effects projected normal regression model. A set of animal-specific parameters following a hidden Markov chain is introduced to deal with unobserved heterogeneity. For the maximum likelihood estimation of the model parameters, we outline an expectation–maximization algorithm. A large-scale simulation study provides evidence on model behavior. The data analysis approach based on the proposed model is finally illustrated by an application to a dataset, which derives from a population of Talitrus saltator from the beach of Castiglione della Pescaia (Italy).     

The Ricker Hills Tillite provides evidence of Oligocene warm-based glaciation in Victoria Land, Antarctica

The relationship between the Ricker Hills Tillite (RHT), which represents the northernmost outcrop of lithified continental glacial deposits in Victoria Land, is discussed with respect to the glacial landscape assemblage of the Ricker Hills, a nunatak at the internal border of the Transantarctic Mountains. A warm-based ice sheet deposited the tillite and induced syn- to post-depositional glacial deformation under wet conditions both of the tillite and of the bedrock. The thickness of the ice sheet on the nunatak is estimated to have been 600 m, at most. The area had been deeply eroded before deposition of the RHT as documented by the low elevation of tillite outcrops located in overdeepened depressions of the nunatak. Micropaleontological analysis evidences only the presence of Permian to Jurassic palynomorphs. X-ray diffraction and SEM–EDS analyses of clay minerals in the RHT indicate continental chemical weathering under wet conditions after the RHT deposition. As documented by clay mineral assemblage variation in CRP drillholes, the progressive cooling of the Antarctic continent allowed chemical weathering in “warm” conditions until the Late Oligocene period in southern Victoria Land, leading to a chronological constrain for RHT deposition. Conservatively estimating the sea level to have been between the tillite outcrops and the erosional trimline limiting horns in the Ricker Hills, at the time of RHT deposition, we suggest that the maximum uplift of the area would not have exceeded 900–1500 m since at least Late Oligocene.     

Methods for point source analysis in high energy neutrino telescopes

Neutrino telescopes are moving steadily toward the goal of detecting astrophysical neutrinos from the most powerful galactic and extragalactic sources. Here we describe analysis methods to search for high energy point-like neutrino sources using detectors deep in the ice or sea. We simulate an ideal cubic kilometer detector based on real world performance of existing detectors such as AMANDA, IceCube, and ANTARES. An unbinned likelihood ratio method is applied, making use of the point spread function and energy distribution of simulated neutrino signal events to separate them from the background of atmospheric neutrinos produced by cosmic ray showers. The unbinned point source analyses are shown to perform better than binned searches and, depending on the source spectral index, the use of energy information is shown to improve discovery potential by almost a factor of two.     

Alluvial terraces on the Ionian coast of northern Calabria, southern Italy: Implications for tectonic and sea level controls

In this paper we present the results of an integrated geomorphological, pedological and stratigraphical study carried out along the Ionian coast of northern Calabria (southern Italy). This area is characterised by the occurrence of five orders of alluvial terraces that are striking features of the landscape, where large and steep catchments debouch from the mountain front to the hilly coastal belt.Field investigations indicate that the deposits of all five terraces are suggestive of shallow gravel-bed braided streams.On the basis of the age of the Pleistocene substratum and morphostratigraphic correlation with marine terraces cropping out in the nearby areas, each order has been associated to specific marine oxygen isotope stages.Consequently, we focused on the interplay of allocyclic factors influencing stream aggradation/degradation. Soil features and other climatic proxies suggest that climate didn't play an important role with respect to tectonic and base-level changes in controlling fluvial dynamics.In particular, we recognised that during the middle Pleistocene the study area experienced a period of subaerial landscape modelling, as suggested by the thick and complex alluvial sequence of the highest terrace (T1). The onset of regional uplift marks a change in the geomorphic scenario, with tectonic and eustatically driven changes in base-level working together in causing switches in fluvial aggradational/erosional phases (T2–T5 terraces). Because of the uplift, river dissection occurred during phases of sea level fall, whereas aggradation phases occurred during periods of climate amelioration (sea level rise) just before highstands were attained.As a consequence, the stepped terraces in the study area reflect the interplay between tectonics (uplift) and sea level changes, in which terraces define episodes of relative sea level fall during the late Quaternary.     

Ultramafic intrusion triggers hydrothermal explosions at Colle Fabbri (Spoleto, Umbria), Italy

The eroded Colle Fabbri volcano comprises intrusive and extrusive rocks which cover an area of about 10,000 m² in the Umbria region, Central Italy. The outcrop is located at the SW boundary of the Umbria Valley Graben (Umbria Region) on an N140 normal fault inside the Intramountain Ultra-Alkaline Province of carbonatite and melilitite rocks of central–southern Italy. A field survey of the outcrop allowed a reconstruction of igneous activity events of this unusual small-scale volcano. It is younger than 0.7 m.y. and rests on Lower Pleistocene conglomerates with intercalated clay beds. A palaeosoil marks the base of the volcanic sequence. It follows several metres of extrusive breccias composed of fragments of thermometamorphosed clay and travertine. Key features of these breccias are mud shells on blocks, plastic mud lumps, slumps, and mechanical injection from one layer into another, as well as plastic and vesiculated, micro-brecciated matrix. The breccias are cemented by a variety of silicate, sulphate, and sulphate–carbonate minerals deposited by intense hydrothermal circulation. The breccias are related to phreatic explosions triggered by the eruption of a superficial hydrothermal system. Up to 1 m thick sill and a dykelet swarm intrude the breccias. In the southern part of the outcrop there is a plug of melilitolitic composition which intrudes the breccias and deforms them upward. A variety of contact breccias is also scattered around the sill and the plug. In some places, hyaloclastite formed when melt invaded water pockets contained in the encasing rocks under hydrostatic pressure conditions. A thermal aureole, which moves up to 10 m away from the contact, is characterised by cordierite–trydimite association, thus indicating high-temperature (>>1000 °C) contact phenomena.     

The Effect of Velocity Inversions on H/V

We analyzed the phenomenology of microtremor H/V curves under inversions in the shear-wave velocity (V_s) profile in the subsoil. Under no V_s inversion the spectral signature of the H/V peaks is found to be ‘eye-shaped’ with the horizontal components higher than the vertical. Conversely, under negative velocity gradients, numerous of differences emerge. I) A H/V ratio below 1 is observed for a wide range of frequencies, due to the decrease of the horizontal components below the vertical one. II) In the presence of persistent H/V < 1, small bumps in the H/V ratio given by local minima in the vertical spectral component may represent the relics of the peaks indicating resonances and stratigraphic discontinuities. As a consequence, in the presence of velocity inversions the H/V > 2 SESAME (2004) criterion fails but a stratigraphic interpretation may still be possible. III) The H/V curves should always be interpreted together with the single component spectra. IV) Microtremor H/V measurements for stratigraphic/microzonation purposes on stiff artificial soils, (asphalt, concrete, cement, pavements) should always be avoided since the latter often produce velocity inversions. This may have consequences in the intermediate to high frequency domain ( > 1 Hz) also in the application of reference site methods, like H_site/H_bedrock, to microtremor. Theoretical modeling confirms these experimental findings.     

Hydraulic Tomography: Continuity and Discontinuity of High‐K and Low‐K Zones

Hydraulic tomography is an emerging field and modeling method that provides a continuous hydraulic conductivity (K) distribution for an investigated region. Characterization approaches that rely on interpolation between one‐dimensional (1D) profiles have limited ability to accurately identify high‐K channels, juxtapositions of lenses with high K contrast, and breaches in layers or channels between such profiles. However, locating these features is especially important for groundwater flow and transport modeling, and for design and operation of in situ remediation in complex hydrogeologic environments. We use transient hydraulic tomography to estimate 3D K in a volume of 15‐m diameter by 20‐m saturated thickness in a highly heterogeneous unconfined alluvial (clay to sand‐and‐gravel) aquifer with a K range of approximately seven orders of magnitude at an active industrial site in Assemini, Sardinia, Italy. A modified Levenberg‐Marquardt algorithm was used for geostatistical inversion to deal with the nonlinear nature of the highly heterogeneous system. The imaging results are validated with pumping tests not used in the tomographic inversion. These tests were conducted from three of five clusters of continuous multichannel tubing (CMTs) installed for observation in the tomographic testing. Locations of high‐K continuity and discontinuity, juxtaposition of very high‐K and very low‐K lenses, and low‐K “plugs” are evident in regions of the investigated volume where they likely would not have been identified with interpolation from 1D profiles at the positions of the pumping well and five CMT clusters. Quality assessment methods identified a suspect high‐K feature between the tested volume and a lateral boundary of the model.     

Bedload hysteresis in a glacier‐fed mountain river

Sediment transport during flood events often reveals hysteretic patterns because flow discharge can peak before (counterclockwise hysteresis) or after (clockwise hysteresis) the peak of bedload. Hysteresis in sediment transport has been used in the literature to infer the degree of sediment availability. Counterclockwise and clockwise hysteresis have been in fact interpreted as limited and unlimited sediment supply conditions, respectively. Hysteresis has been mainly explored for the case of suspended sediment transport, but it was rarely reported for bedload transport in mountain streams. This work focuses on the temporal variability of bedload transport in an alpine catchment (Saldur basin, 18.6 km², Italian Alps) where bedload transport was monitored by means of an acoustic pipe sensor which detects the acoustic vibrations induced by particles hitting a 0.5m‐long steel pipe. Runoff dynamics are dominated by snowmelt in late spring/early summer, mostly by glacier melt in late summer/early autumn, and by a combination of the snow and glacier melt in mid‐summer. The results indicate that hysteretic patterns during daily discharge fluctuations are predominantly clockwise during the snowmelt period, likely due to the ready availability of unpacked sediments within the channel or through bank erosion in the lower part of the basin. On the contrary, counterclockwise hysteresis tend to be more frequent during late glacier melting period, possibly due to the time lag needed for sediment provided by the glacial and peri‐glacial area to be transported to the monitoring section. However, intense rainfall events occurring during the glacier melt period generated predominantly clockwise hysteresis, thus indicating the activation of different sediment sources. These results indicate that runoff generation processes play a crucial role on sediment supply and temporal availability in mountain streams. Copyright © 2014 John Wiley & Sons, Ltd.