289 research outputs found
Physician's mistakes in the interpretation of spirometry
Background. The most recent ATS/ERS recommendations on lung function testing include a definition of airflow obstruction based on lower limit of normal (LLN) of FEV1/FVC and suggest to measure total lung capacity (TLC) in suspected cases of \u201cpseudo-restriction\u201d (normal FEV1/FVC ratio because of concomitant reductions in FEV1 and FVC), that can conceal airflow obstruction if the subject does not exhale long enough.
Aims. To evaluate the skill of physicians in the interpretation of spirometry.
Methods. A questionnaire focusing on the interpretation of five spirograms was administered to 127 physicians (aged 25-67yrs; 39% pulmonologists, 20% geriatrics). Correlates of spirometric misinterpretation were assessed by logistic regression.
Results. Overall, 31% of physicians made at least one mistake in the interpretation of the spirograms administered. The percentage decreases to 15% among pulmonologists (OR=3.7; p=0.005). One quarter of physicians wrongly diagnosed airflow obstruction in a 75yrs old subject with FEV1/FVCLLN.
About 1 out of 5 physicians did not recognize a mixed ventilatory defect (obstruction + restriction), while less than 15% (45% of pulmonologists) highlighted the need to measure TLC in suspected pseudo-restriction.
Factors significantly associated with a lower amount of mistakes included higher n\ub0 of test performed, scientific articles read, respiratory congress attended, COPD and asthma patients visited in the last year.
Conclusions. Inappropriate spirometric interpretation is not rare among physicians and airway obstruction is still frequently overdiagnosed among elderly. Diagnosis by pulmonologists and scientific update of physicians allow to reduce spirometric interpretative errors
Tame majorant analyticity for the Birkhoff map of the defocusing nonlinear Schr\uf6dinger equation on the circle
For the defocusing nonlinear Schr\uf6 dinger equation on the circle, we construct a Birkhoff map \u3a6 which is tame majorant analytic in a neighborhood of the origin. Roughly speaking, majorant analytic means that replacing the coefficients of the Taylor expansion of \u3a6 by their absolute values gives rise to a series (the majorant map) which is uniformly and absolutely convergent, at least in a small neighborhood. Tame majorant analytic means that the majorant map of \u3a6 fulfills tame estimates. The proof is based on a new tame version of the Kuksin-Perelman theorem (2010 Discrete Contin. Dyn. Syst. 1 1-24), which is an infinite dimensional Vey type theorem
Correlation between dental vestibular-palatal inclination and alveolar bone remodeling after orthodontic treatment: A CBCT analysis
The aim of this study was to evaluate the correlation between dental vestibular-palatal inclination changes and the cortical bone remodeling after fixed orthodontic treatment using cone beam computed tomography (CBCT). Twenty-two patients with Angle Class I malocclusion, permanent dentition, and mild to moderate dental crowding were included in the present three-dimensional (3D) analysis. Bone dimensions were evaluated by CBCT scans obtained before and after orthodontic treatment, whereas the torque values were calculated by means of digital models using the 3D VistaDent software. A paired t-test was used to compare the changes between the pretreatment and post-treatment measurements. The correlations between variables were analyzed with linear regression analysis. A significant correlation between torque variations and bone thickness changes was observed for the apical buccal level of the anterior side (P < 0.05). Limited and not significant alveolar bone resorption for the apical thickness of anterior teeth occurred at \ub15 degrees of torque variation, while for tooth inclination exceeding +5 or-5 degrees, the bone remodeling was more evident. The present study demonstrated that anterior region was the most affected area by bone remodeling and that torque variation was highly related to apical bone thickness adaptation for maxillary and mandibular incisors and maxillary canines
A CBCT based analysis of the correlation between volumetric morphology of the frontal sinuses and the facial growth pattern in caucasian subjects. A cross-sectional study
open7noBackground: The aim of this study was to evaluate the relationship between frontal sinus shape and facial growth pattern. Methods: The three-dimensional examination was carried out by means of 80 CBCT scans selected from a sample of 1247 records of patients treated, for different reason, at the Department of Biomedical Surgical and Dental Sciences at University of Milan, Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico Milan. The sample (age ranges between 12 and 40 years) was divided according to gender and age in four groups (12-17, 18-20, 21-30, 31-40). Left and right frontal sinus volume (VOL), surface (SUP) and linear maximum width (XMAX), depth (ZMAX) and height (YMAX) were calculated using Mimics Research 17.0 (Materialise N.V., Leuven, Belgium). Cephalometric analysis has been performed for all subjects to categorize the patients depending on their facial growth pattern. Univariate and multivariate regression analysis were performed to investigate any association of frontal sinuses measurements (height, width, depth, volume and surface) and cephalometric variables. P value < 0.05 was considered statistically significant. Results: A total of 160 frontal sinuses were measures in 80 patients: 40 men and 40 women, average age of 23.5 ±14.6. Globally the frontal sinuses had the following average dimensions: volumes of 9055.8 ± 6505 mm3 and surfaces of 3820.3 ± 2125 mm2. The statistical analysis showed that frontal sinus volume was statistically significant (p=0.003) greater for male (11,425 mm3) than female (6597.5 mm3). Similarly, the surface showed to be greater in men than in women (p=0.005). No correlation between age and frontal sinuses characteristics has been found. A statistically significant (p<0.05) increase of frontal sinus depth, surface and volume was correlated with SNB angle. In addition, frontal sinus volume increased in subjects with greater anterior skeletal dimension values and with a superior length of the cranial base. Furthermore, a decrease of ANB has been found related to an increase in frontal sinus volume (p=0.04). Conclusions: The present study showed a correlation between frontal sinuses dimensions and craniofacial aspects, despite the inter-individual variability of their morphology. The results suggested that young adults in whom the frontal sinuses have reached their maximum size, while vertical growth continues, a larger frontal sinus may be associated with future vertical growth.openAbate A.; Gaffuri F.; Lanteri V.; Fama A.; Ugolini A.; Mannina L.; Maspero C.Abate, A.; Gaffuri, F.; Lanteri, V.; Fama, A.; Ugolini, A.; Mannina, L.; Maspero, C
Comparison of a tridimensional cephalometric analysis performed on 3T-MRI compared with CBCT : a pilot study in adults
OBJECTIVE:
Since the introduction of cone-beam computed tomography (CBCT) in dentistry, this technology has enabled distortion-free three-dimensional cephalometric analysis for orthodontic and orthognathic surgery diagnosis. However, CBCT is associated with significantly higher radiation exposure than traditional routine bidimensional examinations for orthodontic diagnosis, although low-dose protocols have markedly reduced radiation exposure over time. The objective of this preliminary feasibility study is to compare the accuracy and diagnostic capabilities of an already-validated three-dimensional cephalometric analysis on CBCT to those of an analysis on 3-T magnetic resonance imaging (3T-MRI) to assess whether the latter can deliver a comparable quality of information while avoiding radiation exposure.
MATERIALS AND METHODS:
In order to test the feasibility of three-dimensional cephalometry on 3T-MRI, 18 subjects (4 male; 14 female) with mean age 37.8\u2009\ub1\u2009SD 10.2, who had undergone both maxillofacial CBCT and maxillofacial 3T-MRI for various purposes within 1 month, were selected from the archive of the Department of Dentistry and Maxillofacial Surgery of Fondazione Ospedale Policlinico Maggiore, IRCCS, Milano, Italy. A three-dimensional cephalometric analysis composed of ten midsagittal and four bilateral landmarks and 24 measurements (11 angular, 13 linear) was performed on both scans using Mimics Research\uae v. 17.0 (NV, Technologielaan 15, 3001 Leuven, Belgium). Cephalometric analysis was performed twice by two independent orthodontists for each scan, and each orthodontist repeated the measurements 3 weeks later. Statistical analysis was performed with SPSS\uae 20.00 for Windows (IBM\uae Corporation, Sommers, NY, USA). A Bland-Altman test for each cephalometric value was performed to assess the agreement between the procedures. The intraclass correlation coefficient (ICC) was used to assess interobserver and intraobserver reliability. The coefficient of variation was used to evaluate precision.
RESULTS:
Both procedures showed good reliability, with mean intraobserver ICCs of 0.977/0.971 for CBCT and 0.881/0.912 for MRI. The average interobserver ICCs were 0.965 for CBCT and 0.833 for MRI. A Bland-Altman analysis for the cephalometric tracing revealed a similar range of agreement between the two modalities; the bias range (mean\u2009\ub1\u2009SD) was -\u20090.25-0.66\u2009mm (0.174\u2009\ub1\u20090.31) for distances and -\u20090.41-0.54\ub0 (0.12\u2009\ub1\u20090.33) for angles.
CONCLUSIONS:
Within the main limitation of this pilot study, that is, the small sample, it is possible to state that cephalometric measurements on 3T-MRI seem to possess adequate reliability and repeatability and that they show satisfying agreement with values measured on CBCTs. An MRI examination does not expose patients to ionizing radiation and could provide an alternative to CBCT for three-dimensional cephalometrics in the future
Cation-exchange porosity tuning in anionic metal-organic frameworks for the selective separation of gases and vapors and for catalysis
Quantum Poincar\'e Recurrences
We show that quantum effects modify the decay rate of Poincar\'e recurrences
P(t) in classical chaotic systems with hierarchical structure of phase space.
The exponent p of the algebraic decay P(t) ~ 1/t^p is shown to have the
universal value p=1 due to tunneling and localization effects. Experimental
evidence of such decay should be observable in mesoscopic systems and cold
atoms.Comment: revtex, 4 pages, 4 figure
Quantum Poincare Recurrences for Hydrogen Atom in a Microwave Field
We study the time dependence of the ionization probability of Rydberg atoms
driven by a microwave field, both in classical and in quantum mechanics. The
quantum survival probability follows the classical one up to the Heisenberg
time and then decays algebraically as P(t) ~ 1/t. This decay law derives from
the exponentially long times required to escape from some region of the phase
space, due to tunneling and localization effects. We also provide parameter
values which should allow to observe such decay in laboratory experiments.Comment: revtex, 4 pages, 4 figure
Thiazolo[5,4-d]thiazole-2,5-dicarboxylic acid, C6H2N2O4S2, and its coordination polymers
Thiazolo[5,4-d]thiazole-2,5-dicarboxylic acid, C6H2N2O4S2, was isolated as a polycrystalline material, and its crystal structure was determined by ab-initio X-ray powder diffraction (XRPD) methods. This species, upon deprotonation, was subsequently used in preparing the new coordination polymers Ag2(C6N2O4S2), Mn(C6N2O4S2)(H2O)2, Co(C6N2O4S2)(H2O)2, Cu(C6N2O4S2)(H2O) and Zn(C6N2O4S2)(H2O)2, fully characterized by analytical, thermal and XRPD structural methods - including in situ thermodiffractometry and simultaneous TGA and DSC. In the first-row transition metal derivatives, the [C6N2O4S2]2- anion systematically prefers the N,O-chelating, vs. the expected O,O\u2032-bridging, coordination mode, not allowing the formation of porous 3D frameworks. Indeed, these species are dense 1D coordination polymers. At\ua0variance, the silver derivative possesses a complex, dense 3D framework, due to the presence of \u3bc6-[C6N2O4S2]2- ligands showing two \u3bc2-bridging carboxylates and two monohapto N-donor sites. When dehydration is viable, materials of En(C6N2O4S2) formulation are irreversibly recovered (n = 1 for E = Mn, Co, Zn, Cu; n = 2, for E = H)
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