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Clock synchronization is essential to support time-based medium access scheduling and distributed control over industrial networks relying on Real-Time Ethernet (RTE). PROFINET IO is one of the most widely used field-buses in large automation plants. The PROFINET IO Isochronous Real Time (IRT) implementation includes a Precision Transparent Clock Protocol (PTCP) for network-level synchronization. A similar scheme is also used in the second version of the Precision Time Protocol (PTP), standardized as IEEE 1588-2008. Unfortunately, synchronization uncertainty typically grows in the case of long chains of cascaded clocks. In this paper, the accuracy of a clock state estimator based on a Kalman filter is analyzed in the context of PROFINET IO IRT networks. The proposed estimator can be used to compensate the time offsets of every node with respect to the reference master, thus improving synchronization accuracy in the case of long linear topologies beyond the limits of other existing solutions. The presented results are obtained from multiparametric simulations based on the features of real hardware devices.

Real-time networks for substations automation systems are based on ICT technologies and they may take great advantages from ultra recent network technological improvements. A careful evaluation of the performance enhancement is required. Due to cost and system complexity, such an analysis can be performed only using a dedicated simulation environment, but the currently available simulation libraries are not focused on lower layers (L1, PHY, and L2 MAC). The main objective of this work is to introduce the architecture of a modular network simulator, with suitable models of L1 and L2 Ethernet layers, for the simulation and co-simulation of substation automation Real-time Ethernet networks. The modular simulator includes interfaces for both co-simulation with FPGA-hardware board and real network, and co-simulation with automation application software (e.g. IEC61850 SCADA system, etc.).

This paper proposes a novel architecture, compliant to IEC 61850, for a distributed IED based phasor measurement unit to be used in electrical substations. In particular, a measurement architecture based on process bus and sampled values synchronized with IEEE 1588-2008 is proposed, so that voltage and current signals are acquired by a Merging Unit, while the signal processing is performed on a IED (Intelligent Electronic Device) that uses a new algorithm for synchrophasor measurement, in compliance with IEEE C37.118.1-2011.

New needs of distribution system monitoring and automation have been raised in these years as the level of renewable energy sources penetration increases. Monitoring, protection, and synchronization applications needed by new Smart Grid systems mandate a capillary communication with primary and secondary substation, which cannot be implemented in time just with traditional media, such as Fiber Optics. Broadband Power Line over Medium Voltage (MV-BPL) grid could be a viable solution but a comprehensive characterization is still missing. The paper describes an experimental evaluation of service latency in a real MV-BPL design for the distribution grid management in Italy. The preliminary analysis states that 95% of the service requests are transferred on the network with a round-trip time lower than 120 ms even in the case of four hops.

Over the past few decades, centralized computing systems have been replaced by decentralized systems, consisting of simple nodes interconnected by a communication network. The time reference of the distributed nodes must be synchronized in order to be able to coordinate the operation or compare the data collected by the different nodes. Several synchronization protocols have been developed to be used instead of global positioning system or dedicated synchronization systems. For example, the network time protocol (NTP) is a very popular synchronization protocol used to synchronize computers over wide area networks, like the Internet. In addition, IEEE 1588, a synchronization protocol dedicated to high-performance synchronization in local networks, was recently established. However, submicroseconds synchronization can be obtained only using dedicated hardware devices, thereby increasing the cost of each node. For these reasons, PTP software-only implementations are quite common in real systems, with a resulting synchronization uncertainty varying from a few to hundreds of microseconds and quite burdensome to estimate or measure. The work presented in this paper focuses on the analysis of the major uncertainty contributions in a software-only implementation. Particularly, a careful analysis of timestamp mechanism and time management in a PC platform is carried out. In addition, a method for the experimental evaluation of uncertainty contributions is proposed. A test case based on a software implementation of the IEEE 1588 (the so-called PTPd) is presented. The experimental tests presented in the paper highlight that the main uncertainty source of a software-only synchronization approach is the timestamp method. Timestamping accuracy can be affected by the computational load of the node itself: in normal conditions, the maximum uncertainty introduced by the timestamp mechanism is in the order of 10 , but in case of high computational load, it can raise up to 224 μs.

The introduction of the IEC 61850 standard represents a milestone for the Substation Automation System (SAS): the network based control system simplifies the architecture, increasing the interoperability and decreasing the development cost. Looking at the network structure, IEC 61850 defines the Process bus that is used to connect the equipment and sensors which operate close to the power lines. This paper investigates the case in which the Process Bus is opened to other real-time systems that use Real-Time Ethernet protocols. A simulation environment has been used to analyze the Process bus behavior when non IEC 61850 devices are connected (in particular, PROFINET IO devices). The preliminary results suggest the possibility to mix different real-time data streams on the Process Bus, with tolerable variations of the performance of the IEC 61850 applications.

Nowadays, the wide diffusion of smartphones has completely changed the interaction of people with the surroundings. In fact these devices are equipped with a large number of sensors, like GPS receiver, 3-axis accelerator, which can enrich the user experience, collecting data from the external environment. Moreover, additional sensors can be used to enlarge the set of data providing information usually not available in a smartphone, like biomedical data. Usually, Bluetooth is used to connect external sensors to smartphone. Several commercial solutions are already available on the market. Unfortunately, different types of smartphone require the use of dedicated external sensors, due to the different Bluetooth data profile supported by the different Operative System (iOS, Android). In this paper the Bluetooth Hands-Free profile has been evaluated to transmit sensor information to smartphone, since it is the only profile supported both by Android as well as iOS devices. A prototype of a photoplethysmographic sensor with Hands-Free interface has been realized and interfaced to commercial smartphone, showing the feasibility of this approach.

Advantages of wireless fieldbuses, as cabling cost reduction, improved scalability and flexibility, are well known. In particular, the advent of WirelessHART, the first open and standard protocol dedicated to process control, has made wireless adoption a reality in industrial applications. This paper deals with the performance evaluation of WirelessHART network applied to a real-world testbed. The characterization of the network performance is done in the time domain, evaluating the latency of data transfer between sensors and host system. A straightforward but effective test network (comprising a supervisor, a gateway and two nodes) has been designed and implemented, then the impact of wireless and wired link delays have been measured. As a preliminary result, a latency of about 1 s characterizes the interaction between the wireless node and the gateway, although an overall transfer delay of about 3 s is measured at the host application side.

The paper describes the application of an improved Time Gateway for simplifying the integration of old IEC 61850 devices in new IEC 61850 Substation Automation System with IEEE 1588 PTP. Old devices typically retrieve time information with the well-known SNTP protocol which uses very different time representations and synchronization strategies with respect to PTP. Hence, the paper uses a transparent, full-software, Time Gateway for interfacing SNTP devices with a PTP synchronization domain, demonstrating its applicability by means of a prototype based on an FPGA. Experimental results show the Time Gateway improves the overall performance with respect to an SNTP-only system. Moreover, the experiments demonstrate that the synchronization accuracy is limited by the SNTP.

The work presented in this paper is related with time synchronization for wireless networks. In particular, it is focused on the proposal and experimental evaluation of a low-cost and high precision timestamping technique based on Ultra Wide Band (UWB) signalling. In recent years, the use of such systems has gained an increasing success thanks to their robustness to interferers and multipath. In this paper a new hybrid wireless node is proposed; a traditional IEEE802.15.4 radio, the reference physical layer for wireless sensor networks, is supported by an UWB transceiver. The former is used for communication purposes and allows to preserve compatibility with already installed infrastructures/networks; the latter is used for time of arrival estimation. Hardware prototypes have been realized and experimental tests have shown a sub-nanosecond accuracy. A comparison with commercial solutions has shown a performance improvement with respect to conventional approaches.

Nowadays, the energy management is a critical task for suppliers and network operators. A wide use of smart meters may improve the quality of service provided by suppliers thanks to the distributed measuring and controlling capabilities. Recently, the smart metering covers not only electrical distribution, but also other commodities such as gas, water and heat. The German standard OMS (Open Metering System) aims to connect in the infrastructure all the different meters belonging to the same system. In the paper, the advantages of the smart meters are examined and the architecture of OMS network is briefly described. The time requirements of typical meter applications are not strict. However, the estimation of the quality of local power network in a building would require a more accurate acquisition system, in which the time of the meters is synchronized below the millisecond. A characterization of the drift between the clocks of two M-bus meters is required to identify the main limits of the native OMS synchronization mechanism. The relative drift is 8 ppm, which means after 24 hours their time references could differ of 0.7 s.

This paper deals with time synchronization in mixed network infrastructures for automation of industrial and electric plants, where old devices, which retrieve time information with the well-known NTP, must coexist with new IEEE1588 PTP compliant devices. Since PTP and NTP use very different time representations and synchronization strategies, an easy integration is quite difficult and requires additional hardware. The paper describes a transparent Time Gateway that is able to interface SNTP devices with a PTP synchronization domain (PTP devices and PTP switches). The Time Gateway has been realized with an embedded system based on an FPGA with a soft processor and an open source operating system. Preliminary experimental results show the feasibility of the proposed architecture, even if some improvements may be needed to match the time synchronization accuracy required by the legacy SNTP devices.

A reliable source of time is a fundamental requirement for safety critical applications. For this class of applications, synchronization protocols like the IEEE1588 standard, can be adopted. This type of synchronization protocols was designed to achieve very precise clock synchronization, but they may not be sufficient to ensure safety of the whole system. For example an instability of the local oscillator of a reference node could influence the quality of synchronization of all nodes. In the recent years a new software clock, the Reliable and Self-Aware Clock (R&SAClock), which is designed to estimate the quality of synchronization through statistical analysis, was developed and tested. This paper describe and evaluate the design of a protocol for timing failure detection for internal synchronization based on a revised version of the R&SAClock software suitably modified to cross exploit the information on the quality of synchronization among all the nodes of the system.

The International Electrotechnical Commission (IEC) 61850 standard describes the communication inside the substation automation system (SAS) setting the base for new interoperating devices that share information using the Ethernet network infrastructure. More recently, the request of time synchronization among SAS components for the timestamping of critical events or synchrophasor measurement has generated a very high interest in the IEC 61850 working group for distributed synchronization protocols like IEEE 1588. This paper analyzes the current situation, matching different implementations of the IEEE 1588, and their respective accuracy, with the requirements of typical SAS applications: from the millisecond synchronization accuracy required by fault recorder application to the microsecond required by the sampled values (SV). The main focus of this paper is on the integration of IEEE 1588 with real already existing systems, and the goal is the performance comparison of different architectures. For these reasons, experimental tests have been carried out using a real SAS network infrastructure [redundant gigabit optical fiber Ethernet network managed using rapid spanning tree protocol (RSTP)]. The results show that, under ideal conditions, the IEEE 1588 protocol can achieve synchronization accuracy slightly worse (80 ns) than legacy IRIG-B systems (15 ns). However, IEEE 1588 makes possible a great cabling reduction and a simplified maintenance when synchronization is directly transferred on the SAS system bus. On the other hand, experiments highlight that nodes connected through a legacy RSTP infrastructure, which does not support IEEE 1588 messages, can lose the time synchronization in the case of network traffic or reconfiguration of the network. Therefore, the integration of IEEE 1588 over existing IEC 61850 station bus is basically a tradeoff between installation costs and performance since it requires the replacement of already installed Ethernet infrastructure. In the last part, this paper analyses the challenges for the next SAS generation that has to combine on the same plants the high accuracy IEEE 1588 implementation with high-availability protocols based on IEC 62439. Since the lifetime of an SAS is more than ten years and the adoption of these technologies takes several years, some solutions that introduce synchronization and high-availability protocols guaranteeing compatibility with existing technologies have been analyzed, too. For instance, an adaptation block that (when attached to a high-availability network) reconstructs the interface signals (e.g., synchronization signals) required by traditional bay has been proposed.

In the last years, Wireless Sensor Networks experienced a great success in the research community and also the interest of the industrial world seems increasing, as demonstrated by the definition of several standards (e.g. WirelessHART and ISA100.11a). Up to now, network robustness and optimization of the power consumption are the key point of a sensors network. However, the recent technology improvements offer a plenty of processing power and, in this scenario, some background aspects (e.g. advanced networking and time synchronization) cannot be ignored. This paper focuses its attention on synchronization on Wireless Sensor Network based on IPv6 protocol. The integration of IEEE 1588 protocol into this scenario has been analyzed. The synchronization stack has been implemented over a performing platform, which achieves a timestamping accuracy in the order of ±500 ns. However, the synchronization capabilities of the overall system is in the order of 1 ms.

The IEEE1588 became in the last years the de-facto solution to obtain a strict synchronization over a local area network. The purpose of the paper is to analyze the uncertainty sources that affect a software-only implementation of the IEEE1588 (the so called PTPd) based on off-the-shelf PC components. A careful analysis of timestamp mechanism and time management in a PC platform with an Operating System is carried out. The experimental setup presented in the paper highlights that the main uncertainty source of a software-only synchronization approach is the timestamp method. At the end of the paper, an index to evaluate the Timestamping uncertainty, called Timestamping Uncertainty Index (TUI) has been proposed and applied to the test case presented.

Nowadays the IEEE1588 synchronization protocol has been adopted in a growing number of fields, from automation to telecommunication systems. Usually, the quality of the services provided by these applications requires an accurate and reliable time synchronization. Several solutions have been already proposed to achieve these goals. However, the statistical instruments provided in the standard (PTP variance) appear to be inadequate to identify synchronization problems while unpredictable events affect the quality of the synchronization. This paper provides alternative instruments for the analysis and improvement of the synchronization quality of a IEEE 1588 system resorting to the Reliable & Self Aware (R&SA) clock. The R&SA clock provides statistical information which are shown to be able to correctly identify the different sources of problem that can affect the synchronization. The paper then makes a proposal to take advantage of the statistical data collected for improving reliability and accuracy of PTP nodes.

The introduction of the standard IEC 61850 for the communication of Substation Automation System (SAS) opens new scenarios in which products of different vendors can communicate on the same network infrastructure, based on Ethernet technology. The recent improvements in industrial communications are going to deeply influence two of the key points in the development of SAS: synchronization and availability. The challenge of SASs of the future is to combine on the same plants high accuracy synchronization protocols (e.g. IEEE 1588) with high-availability systems in order to increase the overall performance. The integration in real plants is hindered because of the large base of traditional SASs already deployed in the field. In this paper the implementation of mixed scenario SASs, with high-available synchronized Bays together with legacy Bays, is analyzed and a solution for smooth integration is proposed. The idea is based on the use of an adaptation block that, when attached to a high-availability network, reconstructs the interface signals (e.g. synchronization signals) required by traditional Bay.

In the last year the automation systems in power substation start to rely on networks thanks to the introduction of the IEC 61850 standard. Besides, it generates a general interest on synchronization also in the field of substation automation systems. In fact, timestamping of critical events or synchrophasor measurements can have a great advantage from distributed synchronization protocols like IEEE 1588. This paper analyzes the current situation and proposes new architecture for the test of IEEE 1588 solutions before introduction in the market. The focus is mainly on compatibility with real existing systems and its goal is the performance comparison of different implementations. First experimental results on real substation automation system show a great cabling reduction and a simplified maintenance in the IEEE1588-based systems. On the other hand, the synchronization performance are slightly worse: the maximum time difference among clocks of the system is about 80 ns for IEEE1588 with respect to 15 ns of typical IRIG-B-based system.

WirelessHART (WH) is a recently standardized wireless fieldbus. The connection between WH and the host plant network is obtained with Access Points and Gateways. These devices have complex (and costly) architecture, but do not offer flexibility with respect to new update of the specification, and have limited diagnostic capabilities. In this paper, the architecture of a smart WH Access Point, which takes advantage of the Software Defined Radio paradigm, is presented. Thanks to its extreme flexibility and adaptability, it can provide a good investment protection. Moreover, it has additional diagnostic features, like interfering protocol identification and decoding, that keep the network reliable and available. As proof of concept, a prototype of the proposed WH Access Point has been developed using GNU Radio, obtaining the first simulation results.

Wireless Sensor Networks (WSN) are used in a great number of applications. Unfortunately the programming of each node is till now a problem that limits the diffusion of this technology in commercial applications. In fact, in order to meet the strict requirements of the WSN, such as power optimization, specific operative systems (TinyOS) and programming languages have been used. On the contrary, the Sun SPOT platform introduces the Java language and high level programming environment. This very useful feature seems to decrease the synchronization capability of wireless nodes if compared to traditional low-level programming platforms. Aim of this paper is to enhance synchronization and timestamping of Sun SPOT allowing the implementation of time critical applications. Experimental results show how the timestamping resolution has been improved from 1 ms to about 1 µs.

In the last few years solutions adopted in industrial communication have been deeply changed thanks to the adoption of technologies borrowed from completely different areas. In particular, the advent of hybrid wired/wireless networks promises to greatly improve efficiency and scalability. However, their success will depend on the availability of standard solutions, that ensure multivendor compatibility. Recently, the WirelessHART specifications have been released, making it the only available standard for wireless networking in the industrial field. In this paper, authors present an innovative distributed instrument that will make easier the debug and the development of WirelessHART devices and networks.

Wireless communications in the industrial automation world still suffer from lack of standardization. WirelessHART, released in September 2007, is still the only open communication standard specifically designed for real-time process control applications. This paper presents an innovative distributed tool for capturing WirelessHART packets in the field. In fact, even if tools for compliance assessment have been already proposed, an instrument for in situ testing is not yet available. WirelessHART implements a time synchronized mesh network in order to ensure the reliability of the wired counterpart. For this reason, a distributed packet analyzer (“sniffer”) must ensure synchronization among all probes to provide a spatial/temporal image of wireless traffic. The solution we propose is based on commercial-off-the-shelf (COTS) hardware and exploits a wired measuring network that uses IEEE1588 to reach this goal. Several experiments have been conducted in order to verify the feasibility of our proposal and to evaluate performances.

This paper investigates Real-Time Ethernet (RTE) protocols for industrial applications and their clock synchronization performance. In fact, if different RTE protocols coexist on the same network sharing the same infrastructure, clock synchronization capabilities can be affected. This paper introduces a simulation environment to evaluate coexistence of RTE protocols. The proposed tool is described and validated by comparison with measurement data taken from real networks. Finally, simulation results are presented: the behavior of Ethernet/IP with IEEE1588-PTP, when it is transported over an isochronous PROFINET IO network, is shown and some improvements to the PTP tracking algorithms to ease coexistence are proposed.

The definition of several real-time Ethernet (RTE) protocols for industry use implies that new automation systems can include more than one technology. In the future different RTE protocols could share the same network infrastructure, raising the problem of coexistence. The paper introduces a new approach to evaluate coexistence of RTE protocols by means of a distributed RTE traffic emulator/logger that can simultaneously inject RTE traffic and measure its effect on existing infrastructure. In order to experimentally show effectiveness of the proposed method, a prototype instrument has been used to evaluate consequences of mixing RTE protocols that use IEEE 1588 for synchronization and RTE protocols based on time division multiple access. Measurements taken with the proposed instrument have uncertainty in the order of 50 ns.

A survey was performed in a number of Units of Radiology in Santiago, Chile, aimed at obtaining from each medical staff (physicians, technologists and ancillary personnel) estimations on what the Head of a Department of Radiology ideal profile should be. Five out of twelve desirable characteristics proposed had to be selected for statistical purposes. Results were analyzed in correlation with positions, age and workplace of those polled. From our findings we conclude that most valuable leading traits vary from different work units, mainly depending on positions held within each medical Imaging Department. Thus, a proactive leadership demands awareness of such considerations in order to improve organizational practices and results. Key words: Departments of radiology of Santiago, Head of service of diagnosis by images, Survey. Resumen: Se realizo una encuesta en algunos De-partamentos de Radiologia de Santiago, en la cual se consulto a funcionarios no administrativos de estos (medicos, tecnologos y auxiliares paramedicos) sobre los atributos que consideran mas importantes en un jefe de Departamento de Diagnostico por Imagen, mediante la eleccion de 5 de 12 aspectos enunciados. Se analizaron los resultados, relacionandolos con el tipo de cargo desempenado, edad y lugar de trabajo. En este estudio se concluye que los atributos mas valorados en un lider, por los diferentes estamentos dentro de un Servicio de Imaginologia, difieren de-pendiendo de los cargos de los funcionarios, por lo cual, para lograr un trabajo en equipo armonico y fructifero, el lider debe conocer y poner en practica estos aspectos de manera personalizada, en funcion de los intereses de sus subalternos.

If all clocks within a distributed system share the same notion of time, the application domain can gain several advantages. Among those is the possibility to implement real-time behavior, accurate time stamping, and event detection. However, with the wide spread application of clock synchronization another topic has to be taken into consideration: the fault tolerance. The well known clock synchronization protocol IEEE1588 (precision time protocol, PTP), is based on a master/slave principle, which has one severe disadvantage. This disadvantage is the fact that the failure of a master automatically requires the re-election of a new master. The start of a master election based on timeout and thus takes a certain time span during which the clocks are not synchronized and thus running freely. Moreover the usage of a new master also requires new delay measurements, which prolong the time of uncertainty as well. This paper analyzes the results of such a master failure and proposes democratic master groups instead of hot-stand-by masters to overcome this problem by. It is shown by means of simulation that the proposed solution will not deteriorate the accuracy of the slave clocks in case of a master failure.

Se estudió la demanda psiquiátrica en la Asistencia Pública de Santiago durante Mayo de 2005. Se registraron las variables sociodemográficas y clínicas extraídas del formulario de atención. Los diagnósticos se organizaron de acuerdo al CIÉ 10. Se encontraron 562 consultas equivalentes al 5,1% de las atenciones realizadas. Destaca que: 52% eran mujeres; 48%) eran menores de 35 años 54,6%> provenían del Área Central y 60%> tenía gratuidad. El 58%> consultó de 8 a 20 hrs. En términos diagnósticos, destacaron los Trastornos por alcohol y drogas (32,7%>) y los Trastornos neuróticos (51,1%). En los hombres predominaron los Trastornos por alcohol y drogas (58,2%) y los Trastornos neuróticos (31,9%) de los cuales los Trastornos somatomorfos eran el 62,8%; mientras que en las mujeres fueron los Trastornos neuróticos (68.7%), los Trastornos por alcohol y drogas (9,3%) y las Autolesiones intencionales (10%). Se indicó psicotrópicos al 15% de los consultantes e interconsulta a especialista sólo en un 2,5%. La frecuencia de trastornos es similar a la observada en estudios previos. Se constata escasa derivación a especialista o atención psicológica especializada en el establecimiento

This work deals with distributed, multi-probe, instrument for performance analysis of Real-Time Ethernet (RTE) network Particularly, the work is focused on synchronization techniques for distributed measurements. In fact, the accuracy of results (typically jitter and delay) strictly depends on synchronization among distributed probes that sample data. Three synchronization techniques have been implemented and experimental results are reported. Synchronization by means of an external dedicated l-PPS signal gives the best results but requires a more complicated instrument structure. On the other hand, a network-oriented synchronization, such as IEEE 1588 FTP or PCTP (PROFINET 10), can simplify time distribution keeping accuracy well below 1 mus.

The anthropometry-bioimpedance analysis-nutrition (ABN) score is a recently proposed objective method of assessing malnutrition in children on chronic peritoneal dialysis (CPD) that uses nine parameters based on anthropometry, skinfold thickness and bioimpedance analysis. The aim of this prospective, cross-sectional study was to apply it to children treated with CPD in seven Italian paediatric nephrology centres, with a score of < 10.33 (the 3rd percentile in a population of 264 healthy children) classifying the children as malnourished. The other considered parameters were age, age at the start of dialysis and duration of dialysis; serum haemoglobin, urea, creatinine, total protein, albumin, transferrin, bicarbonate and C-reactive protein; residual urine output; urinary and peritoneal creatinine clearance; and daily protein and energy intake. The study enrolled 43 patients (mean age 10.2 +/- 4.2 years), 21 of whom (48.8%) had an ABN score of < 10.33: 15 with mild, five with moderate, and one with severe malnutrition. The malnourished patients started CPD at a younger age (P < 0.05) and had a longer duration of dialysis (P < 0.01), and a significant worsening in nutritional status was observed in those treated for more than 12 months of dialysis; they also had significantly lower serum albumin, creatinine and haemoglobin levels. In conclusion, protein-calorie malnutrition is common in children receiving CPD. A younger age at the start of dialysis and a longer duration of treatment are clear risk factors, and counterbalance the long-term viability of CPD in paediatric age.

Cyclosporin A (CsA) is an effective therapy for children with long-lasting nephrotic syndrome (NS). Long-term treatment can result in chronic CsA nephropathy (CsAN) and there is controversy concerning its incidence and severity. Trough levels are commonly used to monitor the drug concentration. We report a retrospective clinical and histological analysis of 18 children (12 males, 6 females) with steroid-dependent nephrotic syndrome (15 patients) and partially steroid-sensitive nephrotic syndrome (3 patients) treated with CsA for a long-term period (mean 4.9 years, range 2.2–6.9). Before CsA treatment all patients had normal creatinine clearance. CsA was started at a dose of 5 mg/kg per day administered orally in two divided doses and adjusted to maintain the mean CsA blood concentration between 250 and 350 ng/ml obtained from abbreviated area under the curve (AUC). A renal biopsy was performed after a mean period of 3.9 years (range 2.2–6.2) from the start of CsA treatment. Tubular, interstitial, and arteriolar lesions were evaluated in order to assess CsAN. The mean CsA dose and the mean CsA blood concentration were 4.4 mg/kg per day (range 3.6–5.8) and 276.6 ng/ml (range 162–346), respectively. No child had a worsening creatinine clearance during CsA treatment and follow-up after CsA discontinuation. If compared with the year before the start of CsA treatment, NS relapses and prednisone (PDN) dose significantly decreased during CsA treatment, 4/year versus 0.8/year (P

In this study we compared patient and technique survival of 163 new hemodialysis (HD) patients (age 11.4+/-3.1 years) and 295 peritoneal dialysis patients (7.7+/-4.8 years. P0.001), treated in 23 dialysis centers participating in the Italian Registry of Pediatric Chronic Peritoneal Dialysis (CPD) during the years 1989-2000. Three HD (1.8%) and 17 CPD (5.8%) patients died; the overall average death rate was 9.8/1,000 patient-years in HD and 29.8/1,000 patient-years in CPD patients. No statistically significant difference in patient survival between CPD and HD was found, while the survival of 102 CPD children younger than 5 years at the start of dialysis was lower ( P=0.0001) than that of 193 CPD and 160 HD patients aged 5-15 years. We registered 12 modality failures among HD (7.4%) patients and 44 among CPD (14.9%) patients. The main causes were vascular access failure and patient choice in HD, and infection in CPD patients. Technique survival was lower ( P=0.007) in CPD than in HD patients; a statistically significant difference ( P=0.01) was also observed between both the 0- to 5- and the 5- to 15-year-old CPD patients and the HD patients aged 5-15 years. Logistic regression analysis confirmed age at initiation of dialysis to be a predictor of patient death ( P=0.0001) in the whole patient population, and of technique failure in HD ( P=0.006) but not in CPD patients ( P=0.16).

We report our experience with the retroperitoneal laparoscopic approach for treating pediatric patients and when the percutaneous needle approach is not possible due to uncontrolled hypertension, bleeding disorders, anti-clotting medications and anatomical abnormalities.Retroperitoneal laparoscopic renal biopsy was performed in 20 patients 2 to 18 years old (mean age 9.7) during a 16-month period. At the same time 53 percutaneous needle biopsies and 1 open biopsy were performed. The child is in a flank position, and 2 trocars are used via a direct vision approach. The first trocar is 12 mm. in diameter and positioned on the posterior axillary line, and the second trocar is 5 mm. in diameter and is entered 4 cm. anteriorly. Gentle dissection is done to free the lower pole of the selected kidney, biopsy forceps are used to grasp the specimen under direct vision and the biopsy site is fulgurated using bipolar electrocautery.Biopsy was performed successfully in all cases except 1, which was converted to an open procedure. Mean operative time was 40 minutes, blood loss was minimal and mean hospital stay was 1.2 days postoperatively. No pain medication was required postoperatively, and all patients returned to their usual activities within 3 to 5 days. A minor intraoperative complication, which was a peritoneal tear with no postoperative sequelae, occurred in 1 case.The retroperitoneal laparoscopic technique is simple and safe, and does not require extensive laparoscopic experience. We believe that this approach is reliable, and has less morbidity and several advantages compared to open surgery. It should be selected as the first choice for treating pediatric patients when percutaneous needle renal biopsy is contraindicated.

The cutaneous side-effects of levamisole include non-specific and lichenoid eruptions, fixed drug eruption and, very rarely, cutaneous vasculitis. We describe a distinctive clinical and histological vasculopathy with immunological abnormalities in children with paediatric nephrotic syndrome receiving long-term levamisole treatment. Four boys and one girl were identified. Their average age was 10 years. Levamisole had been used for an average of 24 months. Purpura of the ears was the most common finding corresponding histologically to a vasculopathic reaction pattern ranging from a leucocytoclastic and thrombotic vasculitis to a vascular occlusive disease without true vasculitis but with associated antinuclear, antiphospholipid and anticytoplasmic antibodies. The eruption resolved in all patients 2-3 weeks after the discontinuation of levamisole, but serum autoantibodies persisted for 2-14 months.

A 10-year-old female with relapsing gross haematuria and Munchausen syndrome is reported, emphasizing the rarity of this situation in children and the difficult diagnostic pathway. A careful personality study of the patient and family members is absolutely necessary in order to proceed with diagnosis and successful treatment.

OBJECTIVE To compare the efficacy (maintenance of remission), safety and tolerability of cyclosporin (CsA) with those of cyclophosphamide in patients with steroid-dependent or frequently relapsing nephrotic syndrome (NS). DESIGN Open, prospective, randomized, multicentre, controlled study for parallel groups, stratified for adults and children. The setting was in nephrological departments in Italy. SUBJECTS AND INTERVENTIONS Seventy-three patients with steroid-sensitive idiopathic NS admitted to the study were randomly assigned to cyclophosphamide (2.5 mg/kg/day) for 8 weeks or CsA (5 mg/kg/day in adults, 6 mg/kg/day in children) for 9 months, tapered off by 25% every month until complete discontinuation at month 12. Seven patients lost to follow up were not considered in the analysis. The remaining 66 patients were followed up for 3-24 months after randomization. MAIN OUTCOME MEASURES Relapse-free survival; number of N.S. relapses/patient/year; cumulative dose of prednisone/patient; laboratory investigations (kidney and liver functions, haematological parameters); incidence of adverse events. RESULTS At month 9, 26 of 35 CsA-treated patients were still in complete remission and a further five patients were in partial remission; 18 of 28 cyclophosphamide-treated patients were in complete remission, and one in partial remission (P = NS). No difference between adults and children was seen with either treatment. The risk of relapse was similar between frequent relapsers (19 of 22) and steroid-dependent patients (8 of 14) given CsA, and those given cyclophosphamide (5 of 15 and 6 of 15). The mean number of relapses per year and the mean dose of prednisone per year were significantly less (P < 0.001) in both groups for the experimental year than for the year before randomization. At 2 years, 25% of the patients given CsA (50% adults and 20% children) and 63% of those given cyclophosphamide (40% adults and 68% children) had not had any relapse of NS. Tolerance to the two drugs was generally good. The CsA-related side-effects were mild and disappeared after drug discontinuation. CONCLUSIONS This study shows that both treatments are effective and well tolerated; more patients given cyclophosphamide had stable remissions.

The results of the first 3 years' collaboration of the Italian Registry of Paediatric Chronic Peritoneal Dialysis (CPD) (1986-1988) are presented. This Registry acquired data on the majority of the paediatric patients treated with CPD in Italy, thus providing a national picture in a field where few nationwide surveys are available. Patients of less than 15 years of age at the start of dialysis were enrolled and clinical data collected until the age of 19 years. The number of nephrological paediatric centres participating in the Registry increased from 7 in 1986 to 11 in 1988. The total number of patients on CPD was 70 and the percentage of dialysed children treated with CPD ranged from 40.2% to 43.6%. Data on 89 peritoneal catheters were collected: during 1417 dialysis-months 70 catheter-related complications were observed (1:20.8 dialysis-months); actuarial catheter survival was 92.7% at 6 months, 84.8% at 1 year and 68.8% at 2 years. the incidence of peritonitis changed from 1 episode every 10.9 patient-months in 1986 to 1 every 19.8 in 1988. Abdominal hernias were the other main clinical complication observed. The survival of patients was 92.5% at 3 years, while the technique survival at the same time was 84%.

The possibility of altering the direction of polarization of [110] shear waves in cubic ferromagnets is discussed. Using conventional magnetoelastic theory and known elastic and magnetoelastic parameters it is predicted that in ${\mathrm{Tb}}_{0.3}$${\mathrm{Dy}}_{0.7}$${\mathrm{Fe}}_{2}$ it is possible, by rotating an applied magnetic field in the (110) plane, to change the polarization of an incident wave by 90\ifmmode^\circ\else\textdegree\fi{}. The acoustical amplitude in a receiving transducer whose axis was perpendicular to that of the transmitting one was measured in fields from 4 to 10 kOe. The amplitude as a function of orientation is sharply peaked at the angle of field at which a rapid change in normal-mode polarization is predicted.

The rare earth-iron systems, RFe2, have enormous magnetic anisotropy and magnetostriction. They are ferrimagnets, with canting at both sites in the amorphous phase. In amorphous materials the remanence is enhanced by exchange pulling between spins, unlike in large grain polycrystals, and we calculate at lowanisotropy a cutoff in the coercivity, and at large anisotropy/exchange, a proportionality of coercivity to anisotropy. Taking account of exchange, we can fit the composition dependence of Tc and the magnetization, and taking account of anisotropy, we can describe the coercive force and initial magnetization. Next, the elastic properties: Single crystal Terfenol has a 50% reduction in c44 with field, the largest known. In polycrystal and amorphous samples the moment breaks the rotation symmetry. There are then two normal shear wave modes with strain polarizations parallel and perpendicular to the magnetic field. This splitting comes from magnetoelastic coupling and is new effect.