Pleuroparenchymal fibroelastosis in systemic sclerosis: prevalence and prognostic impact

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Functional associations of pleuroparenchymal fibroelastosis and emphysema with hypersensitivity pneumonitis

BACKGROUND: Pleuroparenchymal fibroelastosis (PPFE) has been described in hypersensitivity pneumonitis (HP) yet its functional implications are unclear. Combined pulmonary fibrosis and emphysema (CPFE) has occasionally been described in never-smokers with HP, but epidemiological data regarding its prevalence is sparse. CTs in a large HP cohort were therefore examined to identify the prevalence and effects of PPFE and emphysema. Methods: 233 HP patients had CT extents of interstitial lung disease (ILD) and emphysema quantified to the nearest 5%. Lobar percentage pleural involvement of PPFE was quantified on a 4-point categorical scale: 0 = absent, 1 = affecting 33%. Marked PPFE reflected a total lung score of ≥3/18. Results were evaluated against FVC, DLco and mortality. RESULTS: Marked PPFE prevalence was 23% whilst 23% of never-smokers had emphysema. Following adjustment for patient age, gender, smoking status, and ILD and emphysema extents, marked PPFE independently linked to reduced baseline FVC (p = 0.0002) and DLco (p = 0.002) and when examined alongside the same covariates, independently linked to worsened survival (p = 0.01). CPFE in HP demonstrated a characteristic functional profile of artificial lung volume preservation and disproportionate DLco reduction. CPFE did not demonstrate a worsened outcome when compared to HP patients without emphysema beyond that explained by CT extents of ILD and emphysema. CONCLUSIONS: PPFE is not uncommon in HP, and is independently associated with impaired lung function and increased mortality. Emphysema was identified in 23% of HP never-smokers. CPFE appears not to link to a malignant microvascular phenotype as outcome is explained by ILD and emphysema extents

Transmission line theory for cable modeling: a delay-rational model based on Green's functions

At present, induction motors are controlled via the so-called variable-frequency drives (VFD) that allow to control the speed for the motors. The purpose of this PhD thesis is to improve electromagnetic modeling techniques for the study of conducted electromagnetic emissions in variable-frequency drives, with the aim of enhancing their reliability in energy production plants. Pulse-width-modulated voltage converters are used to feed an AC motor, and they are considered to be the primary reason for high-frequency effects in both the motor and the supply grid. In particular, high-frequency currents, known as common mode currents, flow between all energized components and the ground and travel via low-resistance and low-inductance interconnects such as the power cable between the inverter and the motor.Electrically long power cables are commonly used in VFD installations, and require particular attention. Accurate models can be obtained using the theory of multiconductor transmission lines. In the case of nonlinear terminations, such as an inverter, only time-domain analysis is possible. In recent years, several techniques have been proposed. Some of these techniques include the lumped-element equivalent circuit method, the method of characteristics (MoC) and its generalizations, and the Pad´e approach. In this context, a modeling technique based on Green’s functions has been proposed. The input/output impedance matrix is expressed as a rational series, whose poles and their residues are identified by solving algebraic equations. The primary disadvantage of this method lies in the large number of poles that is typically necessary to model the dynamics of the system, especially when electrically long interconnectsare considered. To overcome this limitation, we have proposed the Delay-Rational Green’s-Function-based Method, abbreviated as DeRaG. In this method, the line delay is extracted and, by virtue of suitable mathematical manipulation of the rational series, is incorporated through hyperbolic functions. The delay extraction enables the use of a reduced number of poles and improves the accuracy of the model in general, avoiding any ringing effects in the time-domain response. The primary advantage of the proposed method compared with other well-known techniques lies in the delayed state-space representation. The obtained model can be computed regardless of the terminations and/or sources, and the terminal conditions can be immediately and essentially incorporated.The next step will be to simulate the entire inverter-cable-motor system. The partial element equivalent circuit (PEEC) technique will be used to model the interconnects as well as the discontinuities in the power cable that can be caused, for example, by switch disconnectors. The theoretical results will be verified against experimental measurements. The final objective is to provide new techniques for modeling the electrodynamics of variable-frequency drives to allow their complete EMC assessment as early as the design stage and to enable the planning of corrective actions in advance.Godkänd; 2016; 20160318 (mardel); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Maria De Lauretis Ämne: Industriell Elektronik/Industrial Electronics Uppsats: Transmission Line Theory for Cable Modeling: A delay-rational model based on Green’s functions Examinator: Professor Jonas Ekman, Institutionen för system- och rymdteknik, Avdelning: EISLAB, Luleå tekniska universitet. Diskutant: Professor Sven Nordebo, Institutionen för fysik och elektroteknik, Linnéuniversitetet, Växjö. Tid: Tisdag 3 maj, 2016 kl 10.30 Plats: A1547, Luleå tekniska universitetFrekvensomriktares funktion i beredskapskritiska syste

Multiconductor transmission lines wideband modeling : A delay-rational Green’s-function-based method

The performance of variable-frequency drives (VFDs) commonly used in energy production plants can be severely affected by electromagnetic (EM) noise in the form of conducted disturbances. A VFD is composed of an inverter, a motor, and a connecting power cable. The insulated-gate bipolar transistor (IGBT) technology and the pulse-width modulation (PWM) technique, used in the inverter, amplified the role of the power cable, which experiences the so-called “high-frequency” or “transmission line” effects, such as reflections, crosstalk, and distortion. Therefore, a complete EM assessment of a VFD requires an accurate and computationally efficient mathematical model of the cable, which can be studied as a multiconductor transmission line (MTL). Accordingly, we developed the “delay-rational Green’s-function-based” (DeRaG) model that should overcome the main limitations of the existing methods in the literature. In the DeRaG model, the impedance (or admittance) matrix is the sum of a rational series and a so-called hyperbolic part realized by hyperbolic functions. The rational series consists of poles and residues and can be truncated to a suitable size by a delay extraction technique. The hyperbolic part retains the primary information of the high-frequency behaviors, such as attenuation and propagation delays, of a line; thus, the DeRaG model is a wideband model. The DeRaG model is independent of the terminations and sources of the line and enables a delayed state-space representation; it can also account for EM interference. Nevertheless, an EM assessment of a complex system can be performed only using a calculator and proper software. Most of the advanced models for MTLs have been adapted for SPICE-like transient solvers. However, power electronics applications are commonly simulated by using software packages such as Simulink that are optimized for system-level simulations. We thus proposed the implementation of the DeRaG model both in SPICE and in Simulink to embrace a larger group of users and applications. The Simulink implementation was notably proven to be extremely simple and easy to describe. In addition, we focused on the hyperbolic part to qualitatively assess the behavior of an MTL. Our investigation resulted in an outstanding outcome; namely, we provided the distortionless condition for MTLs, whereas the distortionless condition was previously defined only for single-conductor transmission lines as the well-known Heaviside condition. In conclusion, the DeRaG model is a wideband model for the EM analysis of generic transmission lines that is suitable for system-level simulations required in power electronics applications and offers new insights into the physics of the system.

Multiconductor transmission lines wideband modeling : A delay-rational Green’s-function-based method

The performance of variable-frequency drives (VFDs) commonly used in energy production plants can be severely affected by electromagnetic (EM) noise in the form of conducted disturbances. A VFD is composed of an inverter, a motor, and a connecting power cable. The insulated-gate bipolar transistor (IGBT) technology and the pulse-width modulation (PWM) technique, used in the inverter, amplified the role of the power cable, which experiences the so-called “high-frequency” or “transmission line” effects, such as reflections, crosstalk, and distortion. Therefore, a complete EM assessment of a VFD requires an accurate and computationally efficient mathematical model of the cable, which can be studied as a multiconductor transmission line (MTL). Accordingly, we developed the “delay-rational Green’s-function-based” (DeRaG) model that should overcome the main limitations of the existing methods in the literature. In the DeRaG model, the impedance (or admittance) matrix is the sum of a rational series and a so-called hyperbolic part realized by hyperbolic functions. The rational series consists of poles and residues and can be truncated to a suitable size by a delay extraction technique. The hyperbolic part retains the primary information of the high-frequency behaviors, such as attenuation and propagation delays, of a line; thus, the DeRaG model is a wideband model. The DeRaG model is independent of the terminations and sources of the line and enables a delayed state-space representation; it can also account for EM interference. Nevertheless, an EM assessment of a complex system can be performed only using a calculator and proper software. Most of the advanced models for MTLs have been adapted for SPICE-like transient solvers. However, power electronics applications are commonly simulated by using software packages such as Simulink that are optimized for system-level simulations. We thus proposed the implementation of the DeRaG model both in SPICE and in Simulink to embrace a larger group of users and applications. The Simulink implementation was notably proven to be extremely simple and easy to describe. In addition, we focused on the hyperbolic part to qualitatively assess the behavior of an MTL. Our investigation resulted in an outstanding outcome; namely, we provided the distortionless condition for MTLs, whereas the distortionless condition was previously defined only for single-conductor transmission lines as the well-known Heaviside condition. In conclusion, the DeRaG model is a wideband model for the EM analysis of generic transmission lines that is suitable for system-level simulations required in power electronics applications and offers new insights into the physics of the system.

[Specific nasal provocative test in allergic rhinitis diagnosis: reliability and standardization]

Specific vasomotorial rhinopathy, or allergic rhinitis is to be seen as a systemic pathology characterized by a condition of hyperactivity, the target organ of which is the nose. Particular attention, among the diagnostic tests, should be reserved to the specific nasal provocative test (sNPT), which has been part of the clinical routine for years but has nonetheless failed to achieve a suitable level of standardization. With this intent, we have devoted the present work to the assay of several phlogosis mediators (tryptase, specific IgE and ECP) before and after performing the sNPT. We have studied 20 patients affected by allergic rhinitis, aged between 13 and 61, with single or multiple allergen sensitivities, but in any case with a predominant sensitization, who underwent sNPT between October 2000 and July 2001. In every patients we performed ECP, tryptase and specific IgE assay via direct incubation in the nasal mucosa, before and after specific nasal provocation. The results of the sNPT (rhinomanometry and symptoms score) were compared with the variations in the phlogosis mediators assayed at nasal level. On the basis of the variations in the rhinomanometric resistance and symptoms score, the sNPT was positive in 10 patients (50%). Tryptase and specific IgE increased to a statistically significant degree (respectively, p = 0.01 and p 0.05). Overall, the simultaneous assay of ECP, tryptase and specific IgE, increasing the sensibility of the sNPT, enabled a positive result to be ascertained in 60% of the subjects examined. The method is furthermore based on the principle of local reactivity in that it assays the phlogosis mediators not at systemic level, but directly in the target organ, showing itself to be more specific than level I and II tests