Natural vs. Anthropic Influence on the Multidecadal Shoreline Changes of Mediterranean Urban Beaches: Lessons from the Gulf of Cagliari (Sardinia)

Urban Mediterranean beaches are often characterized by a fragile and unstable equilibrium that can be easily altered by ongoing climate change and by the increase in human pressure. This may pose serious threats to the survival of beach systems that cannot accommodate these modifications. In this paper, the spatio-temporal shift of the shoreline was investigated along two urban beaches in the Gulf of Cagliari (Poetto and Giorgino; southern Sardinia, western Mediterranean Sea) across a time frame of 62 years (1954–2016). The Digital Shoreline Analysis System (DSAS) ArcGIS™ extension was used to extract different statistical parameters which allowed us to quantify the erosion and accretion rates. These data were further examined in relation to a number of anthropic and natural forcings in order to disentangle the factors controlling shoreline evolution. Eight sectors with interchanging net erosive and accretion trends were identified along the Poetto and Giorgino beaches. In six decades, some sectors of the two study sites appeared to have undergone great shoreline modification as a result of the intense anthropogenic activities impacting these coastal areas. The westernmost portions of both beaches were found to be the most vulnerable to erosion processes; such conditions were likely controlled by the interplaying of local hydrodynamics and by the intense coastal development which affected these sectors. The highest retreat rates (mean end point rate (EPR) = −0.51/year) were recorded in the western limit of Giorgino beach. Along the western limit of Poetto beach, EPR erosion rates (mean EPR = −2.92/year) considerably increased in the years after the artificial beach nourishment carried out in 2002, suggesting that the majority of the nourished material was lost offshore or partly redistributed along the beach. Coastal structures, urban development, river catchment modification, industrial and port activities, beach cleaning and touristic and recreational activities have been identified as the ongoing causes of coastal alteration. If these factors remain constant, under projected climate change scenarios, these beaches are at risk of further increased flooding and erosion. In this context, the application of DSAS appeared as an essential tool, supporting a monitoring system able to provide understanding and, potentially, predictions of the short- to long-term evolution of these beach system

Laser system generating 250-mJ bunches of 5-GHz repetition rate, 12-ps pulses.

We report on a high-energy solid-state laser based on a master-oscillator power-amplifier system seeded by a 5-GHz repetition-rate mode-locked oscillator, aimed at the excitation of the dynamic Casimir effect by optically modulating a microwave resonator. Solid-state amplifiers provide up to 250 mJ at 1064 nm in a 500-ns (macro-)pulse envelope containing 12-ps (micro-)pulses, with a macro/micropulse format and energy resembling that of near-infrared free-electron lasers. Efficient second-harmonic conversion allowed synchronous pumping of an optical parametric oscillator, obtaining up to 40 mJ in the range 750-850 nm

PixFEL: development of an X-ray diffraction imager for future FEL applications

A readout chip for diffraction imaging applications at new generation X-ray FELs (Free Electron Lasers) has been designed in a 65 nm CMOS technology. It consists of a 32 × 32 matrix, with square pixels and a pixel pitch of 110 µm. Each cell includes a low-noise charge sensitive amplifier (CSA) with dynamic signal compression, covering an input dynamic range from 1 to 104 photons and featuring single photon resolution at small signals at energies from 1 to 10 keV. The CSA output is processed by a time-variant shaper performing gated integration and correlated double sampling. Each pixel includes also a small area, low power 10-bit time-interleaved Successive Approximation Register (SAR) ADC for in-pixel digitization of the amplitude measurement. The channel can be operated at rates up to 4.5 MHz, to be compliant with the rates foreseen for future X-ray FEL machines. The ASIC has been designed in order to be bump bonded to a slim/active edge pixel sensor, in order to build the first demonstrator for the PixFEL (advanced X-ray PIXel cameras at FELs) imager

Elettronica dei sistemi digitali

Il testo tratta essenzialmente di circuiti digitali in tecnologia CMOS: partendo dalla descrizione della tecnologia, si introducono alcuni elementi combinatori e sequenziali, per poi affrontare la progettazione di sistemi logici più complessi. Vengono discusse la convenienza economica e le caratteristiche elettriche che si ottengono nella realizzazione di un progetto digitale che utilizzi approcci tecnologici più o meno dedicati: dall’ASIC (Application Specific Integrated Circuit), all’FPGA (Field Programmable Gate Array), per concludere con l’esposizione di alcuni concetti legati alla progettazione orientata al collaudo (Design For Testability), elemento chiave nella industrializzazione di un moderno sistema digitale. Il testo ha come scopo quello di fornire le competenze necessarie per la progettazione di semplici circuiti digitali, evidenziando gli aspetti legati alla realizzazione fisica degli stessi

Seagrass ecosystems status between the sliding baseline syndrome and the need for reference conditions

Marine coastal ecosystems are facing compositional and functional changes due to the increasing human footprint worldwide, and the assessment of their long-term changes becomes particularly challenging in this new "Anthropocene Epoch". Measures of change can be done by comparing the present ecosystem status to a defined baseline representing the reference condition. The "syndrome" of the sliding (or shifting) baselines, which describes the incremental lowering of ecological standards, has become a major concern when long-term changes have to be assessed because an already degraded environment status could be accepted as reference. The challenge of delineating ecosystems change in the context of sliding baselines is particularly relevant along highly anthropized coasts, as the case of the Liguria (NW Mediterranean Sea), where pristine coastal areas could not be expected anymore. The Marine Strategy Framework Directive (MSFD, 2008/56/EEC) suggests three approaches to define reference conditions: i) comparison with the status in Marine Protected Areas (MPAs); ii) use of historical information; iii) modelling. Here we report recent applications of these three approaches in Liguria to assess the status of seagrass meadow ecosystem. Ligurian MPAs are too recent and often insufficiently enforced, so that Posidonia oceanica meadows developing in MPAs are far from the expected good ecological status. Available historical information on seagrass distribution was sometime unreliable. Models are promising but face intellectual difficulties (e.g., choice of descriptors). Validating historical data with predictive models showed effective in delineating the trajectory of change experienced by the Ligurian seagrass meadows. Many meadows have been lost and most are showing structural degradation, which favoured the substitution by alien green algae of the genus Caulerpa and triggered a phase shift in the seagrass ecosystems, with the consequent loss of biodiversity, functioning and economic value of the ecosystem services provided by healthy meadows.</jats:p

A receiver for standard IEEE 1596-1992 scalable coherent interface

A CMOS receiver able to correctly answer to the standard IEEE 1596-1992 Scalable Coherent Interface specifications is proposed. The receiver recognises and translates into CMOS digital levels a differential signal of amplitude down to 100 mV and frequency up to 1 GHz and, with 2.5V of voltage supply, exhibits a power dissipation always lower than 11.5mW and a duty-cycle output always between 45% and 55%, independently on the input common mode value. The circuit has been designed in CMOS technology, 0.25um minimum litography

A self-biased low voltage, low power, CMOS transconductor stage

A self-biased CMOS transconductor stage, able to work with a low-voltage supply and low-power dissipation, is proposed. A fully differential configuration in a 0.25 μm minimum lithography technology has been utilized to design the circuit. Paying particular attention to the mismatch problems, a correct sizing of the circuit has been made. With a voltage supply of 1.2 V, the power consumption is 200 μW and the gain bandwidth product is equal to 30 MHz. Utilizing the transconductor proposed here, a biquadratic cell has been simulated: imposing a central frequency of 1 MHz, the filter reaches 1% of THD with 275 mV peak differential sinusoidal input signal, while the total input noise is about 190 μVr.m.s.. With a power consumption of 1 mW, the cell presents a dynamic range of 60 dB and a SNDR peak of 48.6 d

A CMOS 800-MHz continuous-time biquadratic cell

A CMOS continuous time biquadratic cell with a centre frequency of 800 MHz is proposed. The circuit was designed in a 0.25 um minimum lithography technology using gm-C fully differential configuration. To make a correct sizing of the circuit, particular attention was paid to the mathematical transfer functions of transconductor, integrator and filter. At 2.7 V of voltage supply, the filter presents a power consumption of 51 mW; 1% of THD is reached with 385 mV peak differential sinusoidal input signal, while the total input noise is lower than 319 mVrms. The dynamic range is 58.6 dB and the peak of SNDR is 53.2dB. The necessary integrated capacitance is 4 pF and the total area of the filter is 0.013 mm2

Pipelined inner product function generator

A method for synthesis of pipelined innerproduct function is presented. A merged architecture is at the base of our method. An algorithm for the optimal pipelines insertion in partial product reduction tree is described. Our technique allows designers to obtain fast design of inner product function at a reference frequency. Lower area and lower power are further results achieved by automatic pipelines insertion. Our technique has been implemented by a program that furnishes an optimized netlist. The performance of the latter has been compared to the result obtained by cell-based synthesis software in the design of a pipelined FIR filter for hard disk drive equalization