Affine diffractive beam dividers.

Diffractive optical elements that divide an input beam into a set of replicas are used in many optical applications ranging from image processing to communications. Their design requires time-consuming optimization processes, which, for a given number of generated beams, are to be separately treated for one-dimensional and two-dimensional cases because the corresponding optimal efficiencies may be different. After generalizing their Fourier treatment, we prove that, once a particular divider has been designed, its transmission function can be used to generate numberless other dividers through affine transforms that preserve the efficiency of the original element without requiring any further optimization.

Helical plasma filaments from the self-channeling of intense femtosecond laser pulses in optical fibers: publisher's note.

This publisher's note contains a correction to Opt. Lett.47, 1 (2022)10.1364/OL.445321.

Helical plasma filaments from the self-channeling of intense femtosecond laser pulses in optical fibers.

We experimentally and numerically study the ignition of helical-shaped plasma filaments in standard optical fibers. Femtosecond pulses with megawatt peak power with proper off-axis and tilted coupling in the fiber core produce plasma skew rays. These last for distances as long as 1000 wavelengths thanks to a combination of linear waveguiding and the self-channeling effect. Peculiar is the case of graded-index multimode fibers; here the spatial self-imaging places constraints on the helix pitch. These results may find applications for fabricating fibers with helical-shaped core micro-structuration as well as for designing laser components and three-dimensional optical memories.

Rainbow Archimedean spiral emission from optical fibres.

We demonstrate a new practical approach for generating multicolour spiral-shaped beams. It makes use of a standard silica optical fibre, combined with a tilted input laser beam. The resulting breaking of the fibre axial symmetry leads to the propagation of a helical beam. The associated output far-field has a spiral shape, independently of the input laser power value. Whereas, with a high-power near-infrared femtosecond laser, a visible supercontinuum spiral emission is generated. With appropriate control of the input laser coupling conditions, the colours of the spiral spatially self-organize in a rainbow distribution. Our method is independent of the laser source wavelength and polarization. Therefore, standard optical fibres may be used for generating spiral beams in many applications, ranging from communications to optical tweezers and quantum optics.

Experimental observation of self-imaging in SMF-28 optical fibers.

Spatial self-imaging, consisting of the periodic replication of the optical transverse beam profile along the propagation direction, can be achieved in guided wave systems when all excited modes interfere in phase. We exploited material defects photoluminescence for directly visualizing self-imaging in a few-mode, nominal singlemode SMF-28 optical fiber. Visible luminescence was excited by intense femtosecond infrared pulses via multiphoton absorption processes. Our method permits us to determine the mode propagation constants and the cutoff wavelength of transverse fiber modes.

Synthesis of mesoscale ordered two-dimensional π-conjugated polymers with semiconducting properties.

Two-dimensional materials with high charge carrier mobility and tunable band gaps have attracted intense research effort for their potential use in nanoelectronics. Two-dimensional π-conjugated polymers constitute a promising subclass because the band structure can be manipulated by varying the molecular building blocks while preserving key features such as Dirac cones and high charge mobility. The major barriers to the application of two-dimensional π-conjugated polymers have been the small domain size and high defect density attained in the syntheses explored so far. Here, we demonstrate the fabrication of mesoscale ordered two-dimensional π-conjugated polymer kagome lattices with semiconducting properties, Dirac cone structures and flat bands on Au(111). This material has been obtained by combining a rigid azatriangulene precursor and a hot dosing approach, which favours molecular diffusion and eliminates voids in the network. These results open opportunities for the synthesis of two-dimensional π-conjugated polymer Dirac cone materials and their integration into devices.

Parallelism between risk and perception of risk among caregivers during anesthesia delivery.

The paper examines the different perceptions of risk associated with anesthesia systems from the viewpoint of the product manufacturer and the caregiver. Only a little research has been done with regard to the impact of perception of risk on patient safety in anesthesia. The role of the manufacturer in mitigating the perception of risk will be central for the work. The risk will be examined as the probability of negative occurrences based on the Medical Device Reportable (MDR) events for 2016 and 2017 and it will be examined how the caregiver perceives and manages these risks when delivering anesthesia. Analysis of the manufacturer's public Medical Device Reportable events data will be performed in the US market and will represent the actual risk achieved; this review will provide a perspective on how the risk is perceived and managed by the caregiver when delivering anesthesia. The goals of the paper are to highlight how the role of the manufacturers can have an impact on the reduction of perception of risk, increasing patient safety, and showing how the perception of risk is usually magnified by the hospital personnel.

Benefits and hazards of electromagnetic waves, telecommunication, physical and biomedical: a review.

OBJECTIVE: The aim of this paper is to review the current literature on electromagnetic radiation (EMR): physical, biophysical, and telecommunication. The widespread application of EMR in modern technologies requires telecommunication and healthcare professionals to possess some knowledge of its physical and biological properties. In this review article, we will discuss biophysical principles of EMR, its interactions with living organisms and its application in clinical practices. We will discuss here beneficial as well as hazardous effects of EMR. We will also discuss the safety guidelines.

Electromagnetic scattering by a buried sphere in a lossy medium of an inhomogeneous plane wave at arbitrary incidence: spectral-domain method.

A rigorous theoretical treatment to analyze the electromagnetic scattering of an inhomogeneous elliptically polarized plane wave by a sphere buried in a lossy half-space is presented. To consider the losses in the media an inhomogeneous plane wave is considered. The incident and the scattered electric field components are expanded in series of vectorial spherical harmonics using the Legendre functions generalized via hypergeometrical and gamma functions, with unknown expansion coefficients. The spectral-domain method to represent the scattered electric field is used in order to compute the scattered-reflected and scattered-transmitted fields, considering the reflection and transmission of each elementary plane wave by the interface. Finally, the unknown coefficients of the scattered field are computed by imposing the boundary condition on the spherical surface. In order to validate the model, a homemade code has been implemented. Comparisons with the simulations performed with a commercial software and the results in the literature are presented.

Electromagnetic scattering by two concentric spheres buried in a stratified material.

In this paper, a rigorous method to analyze the electromagnetic scattering of an elliptically polarized plane wave by two concentric spheres buried in a dielectric stratified medium is presented. The interaction of the electromagnetic radiation with the stratified material is taken into account by means of the transfer matrix approach, in this way we can consider the stratified medium as an effective single interface. All the electromagnetic fields are expanded in series of spherical vector harmonics. The transmitted field through the stratified medium is obtained by means of the effective transmission coefficient. This field is scattered by the two concentric spheres, and the scattered field interacts again with the stratified material. The scattered-reflected and scattered-transmitted fields by the layered medium are computed by exploiting the plane-wave spectrum of the scattered field, considering the reflection and transmission of each elementary plane wave by the effective interface. The boundary conditions imposition on the spheres' surfaces leads to a linear system that returns the unknown coefficients of the problem. A numerical code has been implemented to compute the field over all the space. In order to compute the scattered fields, a truncation criterion has been proposed for the numerical evaluation of the series. Finally, to validate the presented method, comparisons between the results of the proposed code and the results of simulations with a software based on the finite element method have been implemented, showing very good agreement.

Vectorial spherical-harmonics representation of an inhomogeneous elliptically polarized plane wave.

In this paper, a generalization of the vectorial spherical-harmonics expansion of an inhomogeneous elliptically polarized plane wave is presented. The solution has been achieved using the Legendre functions generalized via hypergeometric and gamma functions, shifting the difficulty to the determination of only expansion coefficients. In order to validate the presented method, a Matlab code has been implemented. To compare the results a Mie scattering by a sphere is considered, then a truncation criterion for the numerical evaluation of the series is proposed, and the Mie scattering coefficients by perfectly conducting and dielectric spheres excited by an inhomogeneous elliptically polarized plane wave are shown.

Body composition, fat distribution and metabolic characteristics in lean and obese women with polycystic ovary syndrome.

The polycystic ovary syndrome (PCOS), characterized by chronic anovulation and hyperandrogenism, has many features of metabolic syndrome and can be considered a metabolic disease. Approximately 50% of patients with PCOS are overweight or obese with abdominal fat accumulation. Some metabolic alterations and abdominal fat distribution have also been reported in lean women with PCOS. The aim of this study was to evaluate the effect, if any, of obesity on metabolic features, body composition and fat distribution in patients with PCOS. Body composition and abdominal fat distribution (evaluated by DEXA), waist circumference, blood pressure, lipid profile, glucose tolerance and homeostasis model assessment index were determined in 23 lean [mean age 23 +/- 5 yr, mean body mass index (BMI) 22 +/- 2 kg/m2] and 27 overweight-obese (mean age 21 +/- 5 yr, mean BMI 32 +/- 5 kg/m2) patients with PCOS and in 20 age- and weight-matched eumenorrhoic women. Patients exhibited slight but non-significant differences in metabolic parameters, waist circumference, blood pressure and total and abdominal fat content compared with weight-matched controls. None of the lean subjects suffered from metabolic syndrome according to the National Cholesterol Education Program--Adult Treatment Panel III (NCEP-ATPIII) criteria as opposed to 10 overweight-obese patients and three overweight-obese control subjects (37% and 33.3% of each subgroup, respectively). Our data do not show significant metabolic alterations in lean PCOS women. Results indicate that obesity seems to underpin the metabolic alterations exhibited by the overweight-obese patients. However, since women with PCOS are at increased cardiovascular risk, further studies are needed to evaluate metabolic alterations and body composition in these patients.

Hyperthermic antiblastic perfusion in the treatment of locoregional spreading limb melanoma.

On the basis of personal experience and a review of the literature, the authors have evaluated the results obtained with hyperthermic antiblastic perfusion (HAP) for the treatment of stage II, III and IIIAB limb melanoma. The evaluation showed that today HAP may be considered a safe and effective treatment, with a major complication rate ranging between 1% and 4%. In terms of tumor response, locoregional control and survival, this treatment has provided better results than other regional chemotherapeutic modalities and undoubtedly better results than those obtained with conventional, even radical, surgery. The multivariate analysis showed that, of the treatment-related prognostic factors, the minimum tumor temperature influenced the percentage of complete response (CR) to the greatest extent (P<0.03), with a positive trend also with regard to the dosage of the antiblastic drug employed (P<0.08). In turn, the complete response rate was a determinant as far as locoregional control (50%; P<0.0009) and disease-free (51.4%; P=0.0009) and overall survival (63%; P<0.009) rates were concerned. Of the tumor-related prognostic factors, the number of lesions (P<0.0014), sex (P<0.04), and the number of disease recurrences (P<0.01) appear to influence overall survival.

Design of a Binary Grating with Subwavelength Features that Acts as a Polarizing Beam Splitter.

A binary diffractive optical element, acting as a polarizing beam splitter, is proposed and analyzed. It behaves like a transmissive blazed grating, working on the first or the second diffraction order, depending on the polarization state of the incident radiation. The grating-phase profile required for both polarization states is obtained by means of suitably sized subwavelength groups etched in an isotropic dielectric medium. A rigorous electromagnetic analysis of the grating is presented, and numerical results concerning its performances in terms of diffraction efficiency as well as frequency and angular bandwidths are provided.

99mTc-MIBI scintimammography using a dedicated nuclear mammograph.

UNLABELLED: This study reports on a prototype single-photon emission mammograph (SPEM) dedicated to 99mTc-hexakis-2-methoxyisobutile isonitrile (MIBI) scintimammography. Main technical features are reported together with physical performance. Preliminary patient data are also reported. METHODS: The SPEM detector head is composed of a CsI(T1) scintillating array coupled to a Hamamatsu R3292 position-sensitive photomultiplier tube with crossed-wire anode. The high-resolution collimator is 35-mm thick with a 1.7-mm hole diameter and a 0.2-mm septal thickness. The electronic acquisition system is composed of five integrated cards with computation based on high-speed programmable microprocessors. The readout electronics include correction maps for on-line energy correction and spatial uniformity. The small size of the detector head allows the use of mechanical breast compression to minimize detection distance and tissue scatter. After physical SPEM performance evaluation in vivo scintimammography was performed in 29 patients and was compared with a state-of-the-art Anger camera. RESULTS: The SPEM showed an intrinsic spatial resolution of 2 mm, an energy resolution of 23% FWHM at 122 keV and spatial uniformities of 18% (integral) and 13.5% (differential). The SPEM imaged one 0.4-cm carcinoma missed by the Anger camera and resolved as separate lumps an irregular focal uptake on the Anger camera image. The remaining cases yielded concordant results. CONCLUSION: The SPEM prototype presented in this study shows adequate physical characteristics for 99mTc-MIBI scintimammography.

Colorectal Kaposi's sarcoma in an HIV-negative male in association with ulcerative rectocolitis: a case report.

A rare case and the first reported in Italy of a classic form of colorectal Kaposi's sarcoma, associated with ulcerative rectocolitis, is presented. Following a total proctocolectomy, the patient was disease-free at four years. Some epidemiological risk factors such as sex, age, place of birth and both advanced malaria and immunodepressive therapies have also been evaluated. Thus far, only five similar cases have been reported in the literature. However, the epidemiological, clinical and prognostic features of this form of Kaposi's sarcoma must still be investigated.

Effects of IFN alpha on late stages of HIV-1 replication cycle.

IFN alpha causes a modest reduction of HIV-1 expression in chronically infected monocytoid U937 cells. However, the ratio between cell-associated and shed viral p24 antigen is altered, being the cell-associated fraction dose-dependently enhanced by IFN. Furthermore, a significant decrease of infectivity of both cell-associated and shed material is observed. Transmission electron microscopy of IFN-treated cells revealed virus assembly being strongly inhibited, with the production of morphologically altered (tear-drop shaped) virus particles. Proteolytic processing of gag proteins appeared to be normal in IFN-treated cultures. However, virions shed from IFN-treated cells showed a markedly reduced incorporation of virus-specific gp120 and cell-derived ICAM-1 by the virus envelope. Additionally, these particles showed a significantly decreased ability to become bound to CD4+ target cells, accounting for, at least in part, the observed decrease of infectivity. Taken together, the data suggest that, in chronically infected cells, IFN alpha can affect late stages of HIV-1 replication, by inhibiting virus assembly and release, and by reducing the infectivity of shed virions. The latter effect seems to be due, at least in part, to altered incorporation of surface glycoproteins and defective particle formation. The relationship between impaired gp120 incorporation and altered morphogenesis of HIV-1 virions is under investigation.

Magnetic resonance imaging of articular cartilage: ex vivo study on normal cartilage correlated with magnetic resonance microscopy.

The aims of this study were (a) to compare the MR appearance of normal articular cartilage in ex vivo MR imaging (MRI) and MR microscopy (MRM) images of disarticulated human femoral heads, (b) to evaluate by MRM the topographic variations in articular cartilage of disarticulated human femoral heads, and subsequently, (c) to compare MRM images with histology. Ten disarticulated femoral heads were examined. Magnetic resonance images were obtained using spin-echo (SE) and gradient-echo (GE) sequences. Microimages were acquired on cartilage-bone cylindrical plugs excised from four regions (superior, inferior, anterior, posterior) of one femoral head, using a modified SE sequence. Both MRI and MRM images were obtained before and after a 90 degrees rotation of the specimen, around the axis perpendicular to the examined cartilage surface. Finally, MRM images were correlated with histology. A trilaminar appearance of articular cartilage was observed with MRI and with a greater detail with MRM. A good correlation between MRI and MRM features was demonstrated. Both MRI and MRM showed a loss of the trilaminar cartilage appearance after specimen rotation, with greater evidence on MRM images. Cartilage excised from the four regions of the femoral head showed a different thickness, being thickest in the samples excised from the superior site. The MRM technique confirms the trilaminar MRI appearance of human articular cartilage, showing good correlation with histology. The loss of the trilaminar appearance of articular cartilage induced by specimen rotation suggests that this feature is partially related to the collagen-fiber orientation within the different layers. The MRM technique also shows topographic variations in thickness of human articular cartilage.

Assessment of pituitary microadenomas: comparison between 2D and 3D MR sequences.

The aim of this study was to compare the diagnostic value and image quality of two different T1-weighted MR sequences in the evaluation of PRL-secreting pituitary microadenomas. Twenty-four patients with a clinical diagnosis of pituitary microprolactinoma were prospectively examined with both a 2D SE and a 3D turbo-SE T1-weighted coronal sequence, before and after intravenous contrast medium administration. Evaluation of MR images was done only on postcontrast images and considered the number of slices in which the lesions were visible and image quality, which was evaluated by both a subjective score and objective parameters (signal-to-noise and contrast-to-noise ratios). Pituitary microprolactinomas are visible in a higher number of slices in 3D TSE sequences; the subjective scores for image quality and signal-to-noise ratios were similar in both 2D and 3D sequences; the contrast-to-noise ratio was always higher in 3D sequences. In patients with hyperprolactinemia, the authors recommend using coronal 3D TSE T1-weighted sequences for evaluation of the pituitary region. 2D SE T1-weighted sequences may be considered if a shorter examination time is required (i.e., for claustrophobic patients) and in assessment or follow-up of microadenomas when a larger size lesion is clinically suspected.

[Magnetic resonance assessment of knee joint hyaline cartilage according to age, sex, and body weight]. / Valutazione con Risonanza Magnetica degli aspetti delle cartilagini ialine articolari del ginocchio in funzione dell'età, del sesso e del peso corporeo.

To study the MR appearance of knee joint hyaline cartilage, 120 subjects were examined with MRI of the knee. Axial SE proton-density (PD) and T2, GE T1 and GE-MTC sequences were used, as well as coronal SE T1 and sagittal SE PD and T2 sequences. At the patellar and femorotibial cartilages the following variables were investigated: thickness, surface, signal intensity and visibility. Moreover, the three patellar sequences were compared qualitatively, by giving a 1-to-4 score to the images, depending on their yield in the four variables. As for articular cartilage thickness, a statistically significant difference was found between men and women in nearly all measurement sites, the mean values being always higher in men. A statistically significant inverse correlation between cartilage thickness and age was found, in men only, at the three load-bearing regions of the medial femoral condyle. Cartilage surface was irregular and/or its signal intensity altered in 28% of patients at the femoral condyles, while the cartilage of tibial plates exhibited normal surface and homogeneous signal intensity in most cases. The visibility rate of trilaminar cartilage was 82.5% for the medial femoral condyle, 87.5% for the lateral femoral condyle, 70% for the patella, 12.5% for the medial tibial plateau and 14.5% for the lateral tibial plateau. No statistically significant correlation was found between cartilage thickness, surface, signal intensity and visibility and age, sex, and body weight. The GE sequence was the best tool to study cartilage thickness and signal intensity, while the SE T2 sequence was the most accurate one to depict the articular surface and, together with the PD SE sequence, to visualize the trilaminar structure. Our study suggests that articular cartilage surface, thickness, and signal intensity can be studied accurately with SE PD and T2 sequences, combined with a GE T1 sequence.