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Measurement 02/2013; 44:1661–1668. · 0.84 Impact Factor
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ABSTRACT: Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) are performed in patients with obesity and type 2 diabetes mellitus (T2DM). The aim of this study is to evaluate retrospectively the clinical efficacy of RYGB and SG in two groups of obese T2DM patients.
From the hospital database, we extracted the clinical records of 31 obese T2DM patients, of whom 15 (7 F/8 M) had undergone laparoscopic SG (LSG) and 16 (7 F/9 M) laparoscopic RYGB (LRYGB) in the period 2005-2008. The groups were comparable for age (range 33-59 years) and BMI (range 38-57 kg/m(2)). LRYGB alimentary limb was 150 cm, and biliopancreatic limb was 150 cm from the Treitz ligament. LSG vertical transection was calibrated on a 40-Fr orogastric bougie. Data were analysed at 6, 12 and 18-24 months with reference to weight loss and remission of comorbidities.
The reduction in body weight was comparable in the two groups. At 18-24 months the percent BMI reduction was 29 ± 8 and 33 ± 11 % in LSG and LRYGB, respectively. Percent excess weight loss was 53 ± 16 and 52 ± 19 % in LSG and LRYGB, respectively. Thirteen patients in LSG and 14 patients in LRYGB discontinued their hypoglycaemic medications. Five (55 %) patients in LSG and eight (89 %) in LRYGB discontinued antihypertensive drugs. Three out of five patients in LSG and one out of two patients in LRYGB withdrew lipid-lowering agents.
LSG and LRYGB are equally effective in terms of weight loss and remission of obesity-related comorbidities. Controlled long-term comparisons are needed to establish the optimal procedure in relation to patients' characteristics.
Obesity Surgery 10/2012; 22(10):1535-9. · 3.29 Impact Factor
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ABSTRACT: Reliably measuring the relevant parameters (like channel power, occupied bandwidth, and carrier frequency) characterizing the signals involved in wireless communications systems turns out to be the key for their in-service testing at a physical layer. This task, however, would not succeed whenever other signals, generated by different wireless systems, interfere with the useful one both in the time and frequency domains. To overcome this limitation, the authors have recently assessed the suitability of eigenvalue decomposition-based algorithms in accurately estimating the power spectrum of a given number of signals that overlap in the time domain and occupy, fully or partially, the same frequency band. Starting from the promising outcomes of the cited algorithms and taking advantage of some nice features of information theoretical criteria, a new measurement method is designed and implemented hereinafter. Designed directly for the in-service physical layer testing of wireless communications systems, the method allows a blind separation of the power spectrum of the useful signal from those of the interfering ones. The evaluation of the desired parameters of the useful signal as well as the frequency-domain characterization of the interfering ones is thus possible, whatever the number of involved signals. The results obtained in a number of laboratory experiments under different in-channel interference conditions show the reliability and efficacy of the method also in the presence of severe in-channel interference.
IEEE Transactions on Instrumentation and Measurement 04/2011; · 1.21 Impact Factor
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ABSTRACT: This study was undertaken to assess medium-term effects of laparoscopic sleeve gastrectomy (LSG) on body weight and glucose homeostasis in severely obese type 2 diabetic (T2DM) subjects. Twenty-five obese T2DM subjects (10 M/15 F, age 45 ± 9 years, BMI 48 ± 8 kg/m(2), M ± SD) underwent evaluation of anthropometric/clinical parameters and glucose homeostasis before, 3 and 9-15 months after LSG. Mean BMI decreased from 48 ± 8 kg/m(2) to 40 ± 9 kg/m(2) (P < .001) at 3 months and 34 ± 6 kg/m(2) (P < .001) at 9-15 months after surgery. Remission of T2DM (fasting plasma glucose < 126 mg/dL and HbA1c < 6.5% in the absence of hypoglycemic treatment) occurred in all patients but one. There was a remarkable reduction in the percentage of patients requiring antihypertensive and hypolipidemic drugs. Our study shows that LSG is effective in producing a significant and sustained weight loss and improving glucose homeostasis in severely obese T2DM patients.
Journal of obesity 01/2011; 2011:340867.
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ABSTRACT: Frequency spectrum is a limited shared resource, nowadays interested by an ever growing number of different applications. Generally, the companies providing such services pay to the governments the right of using a limited portion of the spectrum, consequently they would be assured that the licensed radio spectrum resource is not interested by significant external interferences. At the same time, they have to guarantee that their devices make an efficient use of the spectrum and meet the electromagnetic compatibility regulations. Therefore the competent authorities are called to control the access to the spectrum adopting suitable management and monitoring policies, as well as the manufacturers have to periodically verify the correct working of their apparatuses. Several measurement solutions are present on the market. They generally refer to real-time spectrum analyzers and measurement receivers. Both of them are characterized by good metrological accuracies but show costs, dimensions and weights that make no possible a use "on the field". The paper presents a first step in realizing a digital signal processing based measurement instrument able to suitably accomplish for the above mentioned needs. In particular the attention has been given to the DSP based measurement section of the instrument. To these aims an innovative measurement method for spectrum monitoring and management is proposed in this paper. It performs an efficient sequential analysis based on a sample by sample digital processing. Three main issues are in particular pursued: (i) measurement performance comparable to that exhibited by other methods proposed in literature; (ii) fast measurement time, (iii) easy implementation on cost-effective measurement hardware.
Measurement Science Review 01/2011; 11. · 0.42 Impact Factor
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ABSTRACT: The performance assessment of worldwide interoperability for microwave access (WiMAX) systems is dealt with. A fully digital signal processing approach for modulation quality measurement is proposed, which is particularly addressed to transmitters based on orthogonal frequency-division multiplexing (OFDM) modulation. WiMAX technology deployment is rapidly increasing. To aid researchers, manufactures, and technicians in designing, realizing, and installing devices and apparatuses, some measurement solutions are already available, and new ones are being released on the market. All of them are arranged to complement an ad hoc digital signal processing software with an existing specialized measurement instrument such as a real-time spectrum analyzer or a vector signal analyzer. Furthermore, they strictly rely on a preliminary analog downconversion of the radio-frequency input signal, which is a basic front-end function provided by the cited instruments, to suitably digitize and digitally process the acquired samples. In the same way as the aforementioned solutions, the proposed approach takes advantage of existing instruments, but different from them, it provides for a direct digitization of the radio-frequency input signal. No downconversion is needed, and the use of general-purpose measurement hardware such as digital scopes or data acquisition systems is thus possible. A proper digital signal processing algorithm, which was designed and implemented by the authors, then demodulates the digitized signal, extracts the desired measurement information from its baseband components, and assesses its modulation quality. The results of several experiments conducted on laboratory WiMAX signals show the effectiveness and reliability of the approach with respect to the major competitive solutions; its superior performance in special physical-layer conditions is also highlighted.
IEEE Transactions on Instrumentation and Measurement 10/2010; · 1.21 Impact Factor
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ABSTRACT: In communication networks setup and tuning activities, a key issue is to assess the impact of a new service running on the network on the overall Quality of Service. To this aim suitable figures of merit and test beds have to be adopted and time-consuming measurement campaigns generally should be carried out. A preliminary issue to be accomplished for is the metrological characterization of the test set-up aimed to provide a confidence level and a variability interval to the measurement results. This allows identifying and evaluating the intrinsic uncertainty to be considered in the experimental measurement of Quality of Service parameters. This paper proposes an original experimental approach suitable for the purpose. The uncertainty components involved in the measurement process are identified and experimentally quantified by means of effective statistical analyses. The proposed approach takes into account the general characteristics of the network topology, the number and type of devices involved, the characteristics of the current services operating on the network, and of the new services to be implemented, as well as the intrinsic uncertainties related to the set-up and to the measurement method. As an application example, the proposed approach has been adopted to the measurement of the packet jitter on a test bed involving a real computer network displaced on several kilometers. The obtained results show the effectiveness of the proposal.
Instrumentation and Measurement Technology Conference (I2MTC), 2010 IEEE; 06/2010
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ABSTRACT: Wireless networks such as WiFi suffer communication performance issues in addition to those seen on wired networks due to the characteristics of the radio communication channel used by their Physical Layers (PHY). Understanding these issues is a complex but necessary task given the importance of wireless networks for the transfer of wide ranging packet steams including video as well as traditional data. Simulators are not accurate enough to allow all the intricacies of such communication to be accurately understood, especially when complex interactions between the protocols of different layers occurs. The paper suggests cross layer measurement as a solution to the problem of understanding and analysis of such complex communication issues and proposes a framework in which appropriate performance measurements can be made from a WiFi network supporting a video streaming application. The framework has been used to collect these measurements at the PHY, MAC, Transport and Application layers. Analysis of the collected measurements has allowed the effects of noise interference at the PHY to be related to the perceived performance at the Application Layer for a video streaming application. This has allowed the effect of the SNR on the download time of a video sequence to be studied.
Instrumentation and Measurement Technology Conference (I2MTC), 2010 IEEE; 06/2010
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ABSTRACT: The capacity of a link is a fundamental parameter in communication networks. Its knowledge is needed for both network planning and management. This is why capacity estimation was one of the first measurement challenges in wired communication networks. In the recent past, some experimental tests permitted imputing the poor performance of capacity measurement techniques in wireless networks to some pitfalls of the capacity model that they are based on. This paper is the natural evolution of those experimental findings. It presents a new multilayer capacity model that is consistent with the classical capacity definition but does not suffer from such pitfalls, along with an improved measurement method based on the deployment of proper software probes. The results of experiments that are conducted on IEEE 802.11x wireless links are also given.
IEEE Transactions on Instrumentation and Measurement 06/2010; · 1.21 Impact Factor
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ABSTRACT: A new cyclostationarity-based method for power measurement in digital communication systems in the presence of in-channel interference is proposed. The new method takes advantage of the signal-selective properties typical of algorithms based on cyclic spectral analysis. The true-power measure is achieved from the noisy data by estimating the cyclic spectrum of the desired signal at a cycle frequency not shared with noise and interference. The performance of the method is evaluated through several experiments on spread-spectrum and pulse-amplitude-modulated signals and with reference to different types of interfering signals. The method exhibits very good performance even when the desired and interfering signals completely overlap in both temporal and spectral domains.
IEEE Transactions on Instrumentation and Measurement 01/2010; · 1.21 Impact Factor
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01/2010;
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ABSTRACT: Impairments affecting the baseband modulator of digital transmitters, which are commonly called I / Q impairments, are responsible for the deviations of symbols from their original position on the I / Q diagram. They cause a reduction in the noise margin and ultimately worsen the probability of error. This is why their measurement is so important in all stages in the life cycle of digital transmitters. This paper presents an original method for the evaluation of the I / Q impairments based on a discrete extended Kalman filter (DEKF). In the same way as alternative solutions already presented in the literature, the method exhibits good performance in the presence of time-invariant impairments. Differently from them, it allows accurate measurements of time-varying impairments, thus making real-time tracking of their evolution feasible. After a few theoretical notes on the I / Q impairments and DEKF, the operative stages of the proposed method are described in detail. Several experiments are then conducted on radio frequency signals to assess the performance of the method; the obtained results are given and discussed.
IEEE Transactions on Instrumentation and Measurement 11/2009; · 1.21 Impact Factor
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ABSTRACT: Digital-video-broadcasting-terrestrial (DVB-T) systems affected by in-channel interference are dealt with here. Attention is mainly paid to the experimental assessment of the video quality perceived by the end user when only in-channel interference degrades the transmission path. To this aim, a number of experiments are conducted through a proper testbed, which enlists a flexible DVB-T broadcasting platform. To confer reliability and generality to the research activity, different configurations of the transmission platform parameters are arranged; moreover, common types of interference are taken into account. Due to a proper cross-layer measurement approach, valuable relations involving values that physical and modulation quantities and application-level metrics assume at the same time are deduced. The ultimate goal is to derive helpful information and hints for designers and technicians that are to be applied to efficiently optimize the performance of a DVB-T system whenever in-channel interference is of major concern.
IEEE Transactions on Instrumentation and Measurement 09/2009; · 1.21 Impact Factor
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ABSTRACT: Measuring capacity of communication links is of utmost importance for both network planning and management. While there are several solutions to the problem of measuring capacity in wired networks, to the best of the authors' knowledge, measuring capacity in wireless links is still an issue. The paper presents a new measurement method for multi-layer capacity estimation, which is based on the insertion of suitable software probes at sender's and receiver's side and overcomes the main limitations of alternative solutions. The results of experimental tests on real wireless networks are provided.
Instrumentation and Measurement Technology Conference, 2009. I2MTC '09. IEEE; 06/2009
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ABSTRACT: Several wireless systems and networks share the same or contiguous frequency bands to provide wideband connectivity. Due to the different channel access techniques, the related communication signals are often transmitted, at the same time, over frequency intervals partially or fully overlapping to one another. In such cases, classical approaches either in the frequency or joint time-frequency domain fail in evaluating the power spectrum of each signal, thus preventing relevant measurement information, like channel power, occupied bandwidth and carrier frequency, to be accurately gained.
Instrumentation and Measurement Technology Conference, 2009. I2MTC '09. IEEE; 06/2009
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ABSTRACT: This paper presents a new method for measuring the I / Q impairments affecting the worldwide interoperability for microwave access (WiMax) transmitters through the analysis of the signal acquired through a general-purpose I / Q receiver. Based on a model of the effects of the I / Q impairments on the output signal that is suitable for orthogonal frequency-division multiplexing (OFDM) systems like WiMax, the method is designed to correctly take into account the peculiarities of systems compliant with the IEEE 802.16-2004 standard, such as the potentially noxious effects of the impairments on signal normalization and threshold decisions. The results of the experiments carried out on the standard-compliant signals are given.
IEEE Transactions on Instrumentation and Measurement 06/2009; · 1.21 Impact Factor
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ABSTRACT: Digital-to-analog converters (DACs) whose time base is affected by deterministic jitter are dealt with. A new model is particularly proposed, which is capable of describing how the desired spectral features of the analog waveform at the output of a DAC are distorted by the presence of sinusoidal timing jitter. In addition to a detailed description of the model, very practical and usable relations are given to make its use very straightforward. Efficacy and reliability of the model are assessed through several experiments on an actual DAC. Jitter effects predicted by the model are compared with those measured on the analog output signals. Special attention is paid to sinusoidal signals, which represent a key stimulus in a variety of application fields. Some tests are also conducted on more complex signals, such as digitally modulated signals peculiar to modern communication systems.
IEEE Transactions on Instrumentation and Measurement 03/2009; · 1.21 Impact Factor
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ABSTRACT: Performance assessment and large-scale monitoring of terrestrial digital video broadcasting (DVB-T) transmission apparatuses are currently a pressing need due to the rapid growth of related broadcasting networks in many countries. Power measurements, in particular, play a very important role since RF and IF signal power, RF channel power, RF and IF power spectrum, noise (or unwanted) power, and power efficiency are relevant parameters to be measured as accurately as possible. Although modern spectrum analyzers and high-performance vector signal analyzers exhibit satisfying accuracy and repeatability, their cost, weight, and size make them unsuitable for the purpose. This paper is focused on the design and realization of a digital signal processing-based meter for power measurement in DVB-T systems that is capable of granting good accuracy, satisfying repeatability, reduced measurement time, and cost effectiveness. This paper deals with the digital signal processing algorithm to be implemented in the meter, paying attention to parametric power spectral density (PSD) estimators for their reduced memory requirement and potentially limited computational burden. In particular, a parametric estimation algorithm that is capable of assuring a fast measurement rate is implemented and made operative. The simulation and emulation stages are properly designed to regulate the most relevant parameters of the adopted PSD estimators according to the specific features of the signals involved; a number of experiments on actual DVB-T signals are conducted, the results of which are compared to those provided by competitive measurement solutions.
IEEE Transactions on Instrumentation and Measurement 02/2009; · 1.21 Impact Factor
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IEEE Transactions on Instrumentation and Measurement 01/2009; · 1.21 Impact Factor
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ABSTRACT: A digital-signal-processing-based instrument for phase noise measurement on sinusoidal signals is described. It incorporates a special hardware architecture, which is made up of a core digital signal processor that is connected to a data acquisition board, and takes advantage of a new measurement procedure based on a quadrature demodulation scheme, which has been proposed by the authors. Thanks to an optimized implementation of this procedure, the instrument exploits all its hardware resources to achieve high performance and real-time operation. For input frequencies of up to some hundreds of kilohertz, the instrument proves to be capable both of updating phase noise power spectrum while seamlessly capturing the analyzed signal into its memory and of granting frequency resolution as good as a few units of hertz.
IEEE Transactions on Instrumentation and Measurement 11/2008; · 1.21 Impact Factor
