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In the published article, there was an error in affiliation(s) 29. Instead of “Departement of Pediatrics, Diabetes Research Institute, IRCCS San Raffaele, Milano, Italy”, it should be “Diabetes Research Institute, IRCCS San Raffaele Hospital, Milan, Italy”. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated.

ObjectiveAfter a previous survey on the incidence of diabetic ketoacidosis (DKA) at onset of type 1 diabetes in children in 2013–2014 in Italy, we aimed to verify a possible decline in the incidence of DKA at onset during a national prevention campaign.DesignProspective observational study.SettingMulticentre study throughout Italy.InterventionNational awareness campaign started in November 2015 and held until December 2017.PatientsDuring 2016 and 2017 we collected data on all patients aged 0–18 years with new-onset diabetes.Main outcome measuresDKA (pH ResultsRecords (n=2361) of children with newly diagnosed type 1 diabetes were collected from 58 out of 68 (85.3%) centres of the original survey participants and 100% of the previously surveyed tertiary centres. Overall, DKA was observed in 1124 patients, with an increased rate when compared with the previous survey (47.6% vs 38.5%, p=0.002), and severe DKA in 15.3%. In children below 6 years, DKA was observed in 323 out of 617 (52.5%) and severe DKA in 16.7%; in this age group, occurrence of DKA reduced by 21.3% (p=0.009). DKA treatment according to the ISPED guidelines was adopted in 95% of the centres, with a 27% improvement (p=0.025).ConclusionsDuring a 2-year awareness campaign, DKA at onset of diabetes in children and adolescents 0–18 years is still common and increased when compared with the 2013–2014 survey.

The acoustic radiation from a pile being driven into the sediment by a sequence of hammer strikes is studied with a linear, axisymmetric, structural acoustic frequency domain finite element model. Each hammer strike results in an impulsive sound that is emitted from the pile and then propagated in the shallow water waveguide. Measurements from accelerometers mounted on the head of a test pile and from hydrophones deployed in the water are used to validate the model results. Transfer functions between the force input at the top of the anvil and field quantities, such as acceleration components in the structure or pressure in the fluid, are computed with the model. These transfer functions are validated using accelerometer or hydrophone measurements to infer the structural forcing. A modeled hammer forcing pulse is used in the successive step to produce quantitative predictions of sound exposure at the hydrophones. The comparison between the model and the measurements shows that, although several simplifying assumptions were made, useful predictions of noise levels based on linear structural acoustic models are possible. In the final part of the paper, the model is used to characterize the pile as an acoustic radiator by analyzing the flow of acoustic energy. © 2013 Acoustical Society of America.

Divers, including closed circuit (rebreather) divers constitute a potential threat to waterside infrastructures. Active diver detection sonars are available commercially but present some shortcomings, particularly in highly reverberant environments. This has led to research on passive sonar for diver detection. Passive detection of open-circuit UBA (underwater breathing apparatus) has been demonstrated, but detection of rebreathers is more challenging due to their quiet operation. A study was conducted using an array of broadband hydrophones (100 kHz bandwidth). 10 hydrophones were arranged in a random array of 1.5 m baseline in order to achieve a favorable tradeoff between angular resolution (requiring a large array), side-lobe rejection (requiring low hydrophone spacing), and cost (requiring a limited number of sensors). The array was deployed from a pier in a basin that is nearby a busy shipping lane in the Port of Rotterdam. A diver equipped with an Inspiration Classic rebreather from Ambient Pressure Diving (a popular recreational rebreather) approached the array, towing a surface GPS that was used for validating detections. The collected data was processed using conventional beamforming and 4th order cumulant based beamforming. The detection of the rebreather at range up to 120 m in presence of shipping traffic was reported and validated against GPS ground truth. This result illustrates the potential of higher order statistics to improve passive acoustic detection. The relatively large detection range suggests that quieter military rebreathers may be detectable at closer range. Furthermore, the limited number of hydrophones used (10) compared to commercial active diver detection sonar, that include typically hundreds of sensors, indicates a strong potential for improvement.

The scattering from roughly meter-sized targets, such as pipes, cylinders and unexploded ordnance shells in the 130 kHz frequency band is studied by numerical simulations and compared to experimental results. The numerical tool used to compute the frequency and aspect-dependent target strength is a hybrid model, consisting of a local finite-element model for the vicinity of the target, based on the decomposition of the three-dimensional scattering problem for axially symmetric objects into a series of independent two-dimensional problems, and a propagation model based on the wavenumber spectral integral representation of the Green's functions for layered media. © 2012 IMACS.

The need for benchmarks of propagation loss, expressed eloquently by Felsen [1], was addressed in a series of propagation workshops in the 1980s. The main results of these workshops were a set of well defined propagation scenarios [2, 3] and a corresponding set of benchmark solutions [4, 5], which led in time to reliable models becoming available throughout the underwater acoustics community. Within the context of sonar performance modelling, these benchmarks provide a valuable means of testing one-way propagation models, and thereby help build confidence in passive sonar performance prediction tools.

Surveillance of waterside locations for protection against threats from small fast surface vessels and underwater intruders is a very relevant but challenging problem. For this reason, the Netherlands Organisation for Applied Scientific Research (TNO) is developing SOBEK – a family of passive sonar technologies for waterside surveillance. The advantages of passive sonar are several-fold: it is low-cost, it allows covert operation, it is not harmful to underwater life, and the reverberation, which can pose significant challenges for active sonar in confined water, is absent. Furthermore, passive acoustic signatures provide a wealth of information for target classification. This paper presents recent developments in our SOBEK passive sonar research, including new results from a 2011 sea trial in the Dutch Navy harbour of Den Helder, and an overview of future system concepts.

Naval mines, underwater improvised explosive devices (UW-IEDs), and underwater unexploded ordnance (UW-UXO) are concerns for harbour security. In conditions without burial, existing commercial systems, such as the REMUS unmanned underwater vehicle equipped with a (very) high frequency side scan sonar (900/1800 kHz), may be deployed for detection and classification. However, it is common that bottom conditions in harbours are such that objects may become covered by mud and sometimes by sand. In the case of burial, a high-frequency sonar system cannot detect objects due to its limited penetration depth. To counter the threat of buried objects in mud, a low frequency (LF: 4-26 kHz) side looking synthetic aperture sonar (SAS) demonstrator system has been developed. This type of system has a bottom penetrating detection potential, combined with a considerable swath. Even with a limited speed of advance (e.g. 2-4 kts) an operationally relevant area coverage rate can be obtained. The system performance has been evaluated in trials in the Haringvliet, an estuary in the Netherlands, conducted in close collaboration with the Royal Netherlands Navy (RNLN). In these trials, it is confirmed that the LF SAS system is capable of detecting buried objects that are not detected by REMUS. Furthermore, buried objects are detected at ranges up to four times the water depth, indicating that a relevant area coverage rate can be achieved

Divers constitute a potential threat to waterside infrastructures. Active diver detection sonars are available commercially but present some shortcomings, particularly in highly reverberant environments. This has led to research on passive sonar for diver detection. Passive detection of open-circuit UBA (underwater breathing apparatus) has been demonstrated. This letter reports on the detection of a diver wearing closed-circuit UBA (rebreather) in an operational harbor. Beamforming is applied to a passive array of 10 hydrophones in a pseudo-random linear arrangement. Experimental results are presented demonstrating detection of the rebreather at ranges up to 120m and are validated by GPS ground truth

A PHD particle filter implementation has been detailed for the fusion of measurements from multiple passive sonar nodes. It has been demonstrated on simulated metadata and on experimental passive acoustic data of divers and small boats collected in an operational port environment. Fusion at the metadata level lowers the necessary data bandwidth, which has practical benefits for long baseline systems. Moreover, the data fusion resolves sensor ambiguities permitting the localisation of targets, and results in an overall improvement in detection performance and a reduction of false alarms. The simulated and experimental results show great promise for our approach to data fusion. However, several improvements can be made and this will be one of the focuses of future work, including: - Improved implementation based on random finite sets (e.g., the Gaussian-mixture PHD filter for efficiency [9] and the cardinalised PHD filter for better performance [10]); - Improvements to the assumed sensor and target models and priors; - Inclusion of more measurements from the acoustic data (e.g., signature features) and possible integration with additional sensor types; - Self assessment of system performance and adaptation (e.g., adjusting the assumed clutter rate based on the conditions, such as during periods of rain or heavy shipping traffic).

Sidescan high-frequency (HF) sonar (i.e., with frequencies higher than 100 kHz) is ideally suited for providing high-resolution images of the seafloor. However, since sound does not penetrate into the sediment at these frequencies, such systems cannot be used for the detection of buried objects, such as naval mines, improvised explosive devices (IEDs), and unexploded ordinance (UXO). Sidescan low-frequency (LF) sonar is a promising technology for the detection of objects buried in soft seafloor sediment. Acoustic energy is attenuated less by the sediment at lower frequencies and can therefore penetrate deeper, facilitating the detection of buried objects. Furthermore, a sidelooking configuration yields a much higher area coverage rate compared to downward-looking systems (e.g., the BOSS system [1]), thus enabling efficient surveys. In practice there are two fundamental issues with sidescan LF sonar. The resolution of conventional sidescan sonar is poor at low frequencies due to the lower directivity of the beams. Moreover, in addition to the targets of interest, many clutter contacts are also observed, including other buried objects (e.g., boulders) and geological features below the mud (e.g., sand ripples). Thus, a means of classification is necessary to distinguish between targets and clutter and to suppress the false alarms. Synthetic aperture sonar (SAS) processing is essential for attaining adequate

Divers and small vessels are increasingly recognized as a potential threat to high value assets. Harbour and waterside surveillance systems that are used to counter the threat of divers are usually based on active sonar, whose performance can be limited by reverberation in a harbour environment. Passive techniques are based on the detection of the sound emitted by the target. They are covert and yield information on the sound radiated by the detected source that can be used for classification. These advantages justify considering passive sonar as the basis for a waterside surveillance system, or as a supplement to a system based on active sonar. Experimental results illustrating some capabilities of passive techniques, such as the detection and tracking of divers and surface vessels using a network of passive nodes, are presented. The experiment was performed in collaboration with the Stevens Institute of Technology (NJ, USA). Possible uses of these techniques in either purely passive systems or to augment active systems are discussed.

Situation awareness is an important component of security that justifies the equipment of sites with monitoring systems. For shore/harbour security, these systems are mostly composed of camera and radar, to monitor the land and the water surface, and of active sonar(s) when the underwater situation is monitored. An alternate approach for underwater monitoring is to use a network of passive sonars that detect targets by the sound they radiate. Unlike active sonar, a single passive sonar element cannot estimate the range of a target in the far field, only its direction; but it can characterize the sound radiated by a target, with obvious applications to target tracking and classification. Passive sonars, with frequency characteristics suitable for the target type of interest, have to be deployed as a network so that the source location can be estimated by appropriately crossing the estimated directions. TNO and the Stevens Institute of Technology are investigating this approach for diver detection and have conducted in 2010 a trial with the support of the Royal Netherlands Navy. A system involved in the trial presented a wide sampling dynamic and frequency range, making it suitable not only for diver detection but also for other forms of processing. Experimental results demonstrate that the deployed system can be used for diver detection and that its larger-than-required dynamic range enables other applications such as boat tracking and sound speed estimation, that can not only augment but improve the initial diver detection capability.

Previously published equations for the time dependence of the echo and reverberation in a Pekeris waveguide are combined with an expression derived for surface-generated noise. These closed form solutions are applied to the calculation of signal to reverberation ratio and signal to total background ratio for three CW pulses with centre frequencies between 250 Hz and 3.5 kHz. The scenario considered is Problem A2.I from the ‘Validation of Sonar Performance Assessment Tools’ meeting of the Institute of Acoustics, held in Memory of David E. Weston, in April 2010. This scenario involves the detection of a spherical target in a Pekeris waveguide, against a background of rain noise and Lambert-rule reverberation from the seafloor

In April 2010, a symposium in Memory of David Weston was held at Clare College in Cambridge (UK). International researchers from academia and research laboratories met to discuss two sets of test problems for sonar performance models, one aimed at understanding mammal echolocation sonar („Problem AI‟), and the other at benchmarking low frequency active sonar models („Problem A2‟) in range-dependent environments. Solutions for Problem A2 have been computed for selected test cases, and an international effort is under way for tackling the first range dependent scenario, which consists of two range independent sections joined by an upslope wedge, with a target in the shallow part of the waveguide and an active sonar in the deeper part, comprising an omnidirectional transmitter and a 65-element horizontal receiving array. The sonar parameters are based on those used for the ONR Reverberation Modeling Workshops of November 2006 and May 2008. The status of the benchmarking effort is discussed, in view of the way forward in this effort, for which the need is perceived in several nations concerned with anti-submarine warfare (ASW) system performance prediction and mission planning.

Ping-to-ping variations in echo level can be caused by time variations in sonar parameters (source level, orientation), target aspect, relative and absolute motion of sonar and target, and time varying environment (e.g. surface waves). Quantifying and understanding such fluctuations are important, since they enable an appropriate choice of receiver operating characteristics (ROC) curve, and suggest strategies for optimizing parameters such as the sonar frequency. One important aspect of this problem is given by the target echo fluctuations due to changes in target aspect and in sonar bandwidth. In some regions of aspect angle-frequency space the fluctuations are stronger and apparently less organized than in other regions. These effects can be explained in terms of scattering physics, and analyzed with high-fidelity target scatter modeling tools, such as those based on finite element methods. This paper presents a numerical study in which one target is analyzed over a broad range of aspect angles and frequencies. The fluctuations in target echo amplitude are studied and characterized in the angle-frequency space, with the objective of obtaining a better understanding of the underlying target-specific echo strength distribution. The result is discussed in view of the construction of target scattering physics-based ROC curves

A set of eight sonar problems, pertaining to man-made active sonar, with source frequencies ranging from 250 Hz to 3.5 kHz, is defined. The scenarios are designed to emphasize range dependent propagation aspects in coastal waters, with the aim of testing all terms of the sonar equation (except the detection threshold) both before and after signal processing, including beamforming and matched filtering. The starting point is a rangeindependent baseline problem, which is a generalization of the Second ONR Reverberation Modeling Workshop problem ‘T’. This problem is successively made more complex by adding surface roughness, summer and winter sound speed profiles, deforming the bathymetry into an upslope and a downslope propagation scenario, and by considering the presence of a solitary wave in the water column of the uniform water depth problem. The capability of modelling sub-bottom rough scattering layers and ship noise is also tested in two range-independent problems. A subset of initial results from a first round of comparisons between computations carried out by the participants of the David Weston Memorial Symposium on the Validation of Sonar Performance Assessment Tools, held in Cambridge on 7 – 9 April 2010, is presented

The Validation of Sonar Performance Assessment Tools Symposium, organised by the Institute of Acoustics was held in Cambridge, UK on 7-9 April 2010. The meeting was held in memory of David E. Weston and consequently is also known as the “Weston Memorial Symposium”. Two sonar scenarios were considered for the Weston Memorial Symposium, one man-made (low frequency active sonar) scenario and one bio-sonar scenario. The bio-sonar scenario, inspired by the work of [Au et al 2004] on a killer whale (Orcinus orca) hunting its prey of chinook salmon (Oncorhynchus tshawytscha), is the subject of the present paper. The problem is specified in Sec. 2 and an example solution is presented in Sec. 3, including the effect of reverberation on detection performance (not part of the problem specified). Solutions for the orcasalmon problem specified in Sec. 2 are also given by [Ehrlich 2010].

Understanding acoustic scattering from objects placed on the interface between two media requires incorporation of scattering off the interface. Here, this class of problems is studied in the particular context of a 61 cm long, 30.5 cm diameter solid aluminum cylinder placed on a flattened sand interface. Experimental results are presented for the monostatic scattering from this cylinder for azimuthal scattering angles from 0° to 90° and frequencies from 1 to 30 kHz. In addition, synthetic aperture sonar (SAS) processing is carried out. Next, details seen within these experimental results are explained using insight derived from physical acoustics. Subsequently, target strength results are compared to finite-element (FE) calculations. The simplest calculation assumes that the source and receiver are at infinity and uses the FE result for the cylinder in free space along with image cylinders for approximating the target/interface interaction. Then the effect of finite geometries and inclusion of a more complete Green's function for the target/interface interaction is examined. These first two calculations use the axial symmetry of the cylinder in carrying out the analysis. Finally, the results from a three dimensional FE analysis are presented and compared to both the experiment and the axially symmetric calculations. © 2010 Acoustical Society of America.

The diagnosis of GH deficiency (GHD) is based on the measurement of peak GH responses to pharmacological stimuli. Pharmacological stimuli, however, lack precision, accuracy, are not reproducible, are invasive, non-physiological and some may even be hazardous. Furthermore, different GH commercial assays used to measure GH in serum yield results that may differ considerably. In contrast to GH, IGF-I can be measured on a single, randomly-obtained blood sample. A review of the available data indicates that IGF-I measurement in the diagnosis of childhood-onset isolated GHD has a specificity of up to 100%, with a sensitivity ranging from about 70 to 90%. We suggest an algorithm in which circulating levels of IGF-I together with the evaluation of auxological data, such as growth rate and growth, may be used to assess the likelihood of GHD in pre-pubertal children.