86,712 research outputs found
Early prediction of hypocalcemia following total thyroidectomy using combined intact parathyroid hormone and serum calcium measurement
No full textBackgrounds Concomitant intact parathyroid hormone
(iPTH) and serum calcium measurement is deemed to be
useful in predicting hypocalcemia after total thyroidectomy.
This study aimed to prospectively assess the diagnostic
accuracy of combined iPTH and serum calcium measurement
in predicting early postoperative hypocalcemia.
Methods From January 2010 to January 2011, 112 patients
underwent total thyroidectomy in our department. A prospective
study was carried out to search for factors predicting
postoperative hypocalcemia. Serum calcium, phosphorus, and
iPTH levels have been measured before operation and at 6, 24,
and 48 h postoperatively. Hypocalcemia was defined as a
serum calcium level less than 8.0 mg/dL. Sensitivity and
specificity of different serum measurements have been calculated
using the receiver–operator characteristics curve.
Results Thirty-three patients (29.5 %) had transient postoperative
hypocalcemia. Serum iPTH level showed the highest
sensitivity and specificity in predicting hypocalcemia after
6 h (84.8 % and 93.7 %, respectively) for a criterion
value ≤12.1 pg/mL. Serum calcium level showed the
highest sensitivity and specificity after 24 h (93.9 and
100.0 %, respectively) for a criterion value ≤7.97 mg/
dL. Combined cutoffs of 6-h iPTH and 24-h serum
calcium showed sensitivity and specificity of 100.0 %.
Conclusions The combined measurement of 6-h iPTH
and 24-h serum calcium are highly predictive of early
postoperative hypocalcemia. Patients with serum iPTH
and calcium level≤criterion value are at major risk for
developing hypocalcemia. These results are important
in selecting patients eligible for early discharge and
those patients who need calcium and vitamin D
supplementation
AN EXPERIMENTAL INVESTIGATION ON ISOTHERMAL FREE SWIRLING JET
No full textThis paper reports an experimental investigation on the dynamics of turbulent unconfined swirling flows. Isothermal free swirling jets with five different swirl
numbers (S) and fixed Reynolds number (Re = 21800) are investigated to analyze the effect of swirl intensity on the recirculation, vortex breakdown and the occurrence of the precession vortex core (PVC) by means of 3C-2D Stereoscopic Particle image velocimetry (PIV). The contours and radial profiles of mean axial velocity confirmed the central recirculation zone (CRZ) for high swirl number. The importance of central recirculation zone is to ensure a good mixing of air/ fuel and combustion products and to generate a low velocity region for flame stabilization. Results shows that swirl intensity increases the backflow rate in the recirculation zone and jet spreads almost linearly with a higher spread rate as compared to non swirling flow. The frequency characteristics have been measured with a capacitive microphone. The frequency spectrum indicates the presence of periodic oscillation related to the
existence of PVC. The Strouhal number associated with the frequency of the PVC vary almost linearly with swirl intensity
MEASUREMENT OF ENTRAINMENT RATE IN THE INITIAL REGION OF SWIRLING JETS
No full textThe entrainment rate in the initial region of axisymmetric turbulent swirling air jets has been measured by Particle Image Velocimetry (PIV) for a number of swirl strengths from S = 0 up to S = 1.5 and two Reynolds numbers. From the complete PIV maps of the jet and its surroundings, entrainment has been evaluated by using two methods: a) integration of the radial profiles of time-mean axial velocity of the jet; b) direct measurements of the radial velocity component of ambient air entrained into the jet. The entrainment rate increases with increasing axial distance from the nozzle in a non linear way and shows a rapid enhancement with the swirl number, particularly after inception of vortex breakdown and when the processing vortex core (PVC) is observed. The results allow to better understand the entrainment process in swirling jets and related effects on mixture formation and flame structure in industrial burners
Studio del deficit di alfa-1 antitripsina nella popolazione Sarda
No full textIntroduzione:
L’ AATD e’ una forma genetica abbastanza comune di malattia epatica nel bambino e di enfisema polmonare ed epatopatia nell’adulto, pur facendo parte delle malattie rare. Si manifesta spesso con sintomatologia clinica aspecifica, con tempi e modalità variabili, e spesso non sono utilizzati i test molecolari per una diagnosi definitiva. La diagnosi di laboratorio è spesso casuale e può essere posta partendo dall’assenza del picco delle α1-globuline all’ESP. Tale carenza induce a sospettare l’AATD, che deve essere prima confermata con il dosaggio sierico e quando necessario deve essere studiato il profilo genico. Per questi motivi, è ragionevole pensare che l’AATD sia una condizione clinica sottostimata, da considerarsi probabilmente non una malattia rara, ma raramente diagnosticata. In Sardegna i casi di AATD sono correlati ad una mutazione nota come M-Malton/ M-Cagliari, rarissima nelle altre popolazioni, o alla mutazione S. Non disponiamo ancora di dati attendibili circa la frequenza di questa mutazione. Scopo del lavoro è quello di individuare i soggetti con AATD e calcolare la frequenza della mutazione nella popolazione da noi considerata, trovare un cut-off decisionale di laboratorio da utilizzare per stabilire quali pazienti studiare per la mutazione
Effect of injection conditions on penetration and drop size of HCCI Diesel sprays
No full textAbstract.
The more recent development in Diesel engines and the ongoing study of the HCCI concept will probably require, in a next generation of engines, early fuel injection in air at low pressure and density to reach a correct mixing and to match evaporation and ignition requirements. In this work different common rail nozzles, fed with fuel supplied at constant pressure in the range from 30 to 100 MPa, were used to produce sprays in air at ambient temperature and pressure ranging from 1 to 7 bar, to investigate the spray penetration as a function of air and fuel pressure. From the experimental results a scaling low was then deduced, which is able to account for different penetration curves in the various tests by a unique common behavior: a linear penetration part, whose length is function of the air density and of the nozzle diameter, followed by a decrease of the tip velocity. Best fit interpolation of the scaled results allowed the definition of a correlation that can predict the spray tip penetration in a wide range of conditions. For a reduced set of experimental conditions drop size and velocity were measured by phase Doppler anemometry; phase averaged mean diameter was then computed and analyzed as a function of the fuel injection pressure, and showed a clear reduction of the drop diameter with increasing injection pressure
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