Quantization Of Spin Direction For Solitary Waves In A Uniform Magnetic Field

It is known that there are nonlinear wave equations with localized solitary wave solutions. Some of these solitary waves are stable (with respect to a small perturbation of initial data) and have nonzero spin (nonzero intrinsic angular momentum in the center of momentum frame). In this paper we consider vector-valued solitary wave solutions to a nonlinear Klein-Gordon equation and investigate the behavior of these spinning solitary waves under the influence of an externally imposed uniform magnetic field. We find that the only stationary spinning solitary wave solutions have spin parallel or anti-parallel to the magnetic field direction.Comment: 4 page

Risk assessment illuminotecnico in ambiente ospedaliero: il caso di studio dell'Ospedale "Felice Lotti" di Pontedera

Nella presente Tesi è stato esaminato il risk assessment illuminotecnico nel caso di studio dell’Ospedale “Felice Lotti” di Pontedera dove sono state effettuate valutazioni del rischio in 9 ambienti opportunamente selezionati. Le misurazioni effettuate con luxmetro e luminanzometro sono state elaborate secondo il metodo di valutazione del rischio, messo a punto nel corso del Piano Mirato Triennale per l’Area Tematica 3, che prevede l’utilizzo di fattori di rischio con l’attribuzione di un coefficiente di scostamento e di un coefficiente di pertinenza, dal cui prodotto si ottiene un indice di rilevanza. Nei locali considerati sono stati individuati i fattori di rischio che presentavano i valori più elevati dell’indice di rilevanza e sono state elaborate delle simulazioni di progetto illuminotecnico con l’ausilio del software Dialux 4.11 per risolvere queste criticità

Diagnostic performance of reformatted isotropic thin-section helical CT images in the detection of superior semicircular canal dehiscence

Purpose The purpose of this article is to assess the diagnostic performance of computed tomography (CT) reformatted images for detection of superior semicircular canal (SSC) dehiscence. Material and methods Forty-two patients, with sound- and/or pressure-induced vestibular symptoms, and 42 control participants underwent helical CT examination with a highly collimated beam (0.5 mm). Reformatted images of the vestibular labyrinth were obtained in the standard axial and coronal planes (group A images), and in a plane parallel and perpendicular to the SSC (group B images). Diagnostic performance obtained by evaluating the group A images alone and the group B images alone was analyzed by using the area under the receiver operating characteristic curve (AUC). Results The diagnostic performance of group A images was AUC = 0.929 with an overall accuracy of 92.9%. The diagnostic performance of group B images was AUC = 0.988 with an overall accuracy of 98.8%. The evaluation of group B images alone showed an improved diagnostic performance over the group A images alone. Conclusion Thin-section 0.5-mm collimation CT with reformatted images oriented in the plane parallel and perpendicular to the SSC improves diagnostic accuracy in assessing for SSC dehiscence in comparison to CT images with reconstructions limited to traditional axial and coronal planes

Exact multiplicity of positive solutions in semipositone problems with concave-convex type nonlinearities

We study the existence, multiplicity, and stability of positive solutions to: \eqalign{- u''(x) &= \lambda f(u(x)) \ \text{for} \ x \in (-1, 1), \lambda > 0, \cr u(-1)&= 0\ = u(1) ,} where $f : [0, \infty) \to \Bbb R$ is semipositone ($f(0) 0$, we obtain the exact number of positive solutions as a function of $f(t)/t$ and establish how the positive solution curves to the above problem change. Also, we give examples where our results apply. This work extends the work in [1] by giving a complete classification of positive solutions for concave-convex type nonlinearities

Peritumoral perfusion and proton spectroscopic MR imaging in the differentiation of gliomas and solitary metastases

Purpose: To asses the value of peritumoural perfusion-weighted and proton spectroscopic MR imaging in preoperative grading of gliomas and in differentiating between primary gliomas and solitary metastases. Methods and Materials: Ten low-grade gliomas, eight high-grade gliomas, and ten metastases were prospectively evaluated with MR imaging, dynamic susceptibility contrast-enhanced perfusion imaging, and single-voxel proton MR spectroscopy before surgical resection or stereotactic biopsy. Maximal rCBV values and maximal Cho/Cr ratios were calculated from peritumoural region surrounding the tumour. Tumour grade presumed with these values was compared to histopathologic grading. Differences in the study parameters between groups were assessed using the Mann-Whitney test. A Receiver Operating Characteristic analysis was performed to determine cutoff values. Results: A clear rCBV cutoff value of 1.88 was detected for differentiating low-grade gliomas from high-grade gliomas (sensitivity 100%, specificity 90%, area under the ROC curve .994, p< 0.0001). A clear rCBV cutoff value of 1.20 was detected for differentiation of metastases from gliomas (sensitivity 100%, specificity 90%, area under the ROC curve .972, p< 0.0001). The differences in the Cho/Cr ratios in the peritumoural regions of high-grade gliomas and of solitary metastasis were statistically significant (p<.001) but a clear cutoff value was not found. Conclusion: Our preliminary data support that peritumoural perfusion-weighted imaging can assist in preoperative differentiation between a glioma and a solitary metastasis, along with separating high-grade gliomas from low-grade gliomas