Search

We report on third-harmonic (TH) generation emitted from 1D photonic slabs etched into Silicon-on-Insulator (SOI) planar waveguides, as compared to the bare waveguide and (100) Silicon bulk responses. 130-fs laser pulses at ~ 810 nm and ~1550 nm have been chosen as a pump to excite TH signals in reflection and diffraction directions. The measured angles of in-plane diffracted third-harmonic beams agree with those predicted by nonlinear diffraction equations. The nonlinear reflectance as a function of the angle of incidence and azimuthal orientation of the structure has been measured. The near-infrared measurements have revealed that, whenever the pump frequency is resonant with a photonic mode, a substantial enhancement of the harmonic signal occurs. This nonlinear mechanism is in principle a very sensitive spectroscopic tool in determining and mapping the photonic band diagram of the system above the light line. The agreement between experimental data and ad hoc simulations of the nonlinear behavior of the system sheds new light on the nonlinear optical response of these nanostructured materials.

This paper reports on nonlinear optical investigations of 2D photonic crystals etched into GaAs/AlGaAs waveguides by means of second-harmonic generation (SHG) from the surface of the samples. 130-fs laser pulses from a tunable Ti:sapphire source at 800 nm and from an optical parametric oscillator in the range 1.4 to 1.6 micron have been chosen to excite SH signals in reflection and diffraction directions. The measured angles of diffracted second-harmonic beams agree with those predicted from nonlinear diffraction conditions. The intensities of the reflected and diffracted SH signals are measured by varying the angle of incidence, input polarization and wavelength. Their observed behavior reflects the GaAs crystalline symmetry and the photonic crystal structure, respectively. Moreover, the measured high diffraction-to-reflection intensity ratio suggests the possibility of tailoring the nonlinear response using diffraction modes.

Summary form only given. Second and third harmonic signals generated in reflection and diffraction from the surface of photonic crystal (PC) waveguides are considered as a spectroscopic diagnostic tool in two leading material systems: GaAs and Silicon. Measurements of second harmonic generation (SHG) in reflection from GaAs-based 2D patterned planar waveguides reveal resonant interaction of the impinging radiation with the quasi-guided modes of the photonic structure. Spectral and angular dependence of these effects reflects the structure of the sample and may be used for an accurate energy and momentum positioning of the photonic bands. Preliminary results of third harmonic generation (THG) from Si-based 1D patterned planar waveguides in the visible spectral range are also presented, indicating harmonic generation as a possible route towards systematic characterization and description of photonic structures.

Linear and nonlinear optical measurements on GaAs/AlGaAs photonic crystal waveguides with square lattice are reported. Second-harmonic generation in reflection shows a resonant enhancement when the pump beam is frequency- and momentum-matched to a photonic mode in the slab. A full three-dimensional theory of waveguide-embedded photonic crystals allows to determine the dispersion of photonic modes and the intrinsic radiative losses of quasi-guided modes lying above the light line.

Innovative approaches are presented for the computational simulation of planar array antennas. They are based on the integral-equation (IE) formulation at large, and consistently employ synthetic local and global basis functions. The local basis function are provided by the full-wave solution of a reduced problem of small size, but with the same local boundary conditions and relevant IE. The global basis function are indeed provided by asymptotic solutions of a canonical array. Numerical examples are shown, which demonstrate the efficiency and accuracy of the proposed methods for patch arrays and open ended waveguide arrays.

The cumulative costs of diagnostic and interventional procedures in the catheterization laboratory in public hospitals are still largely unknown, notwithstanding the present stress upon the cost-effectiveness issues in medicine.From January through April 2000 we have evaluated procedures in the catheterization laboratory of the Ravenna USL. Costs taken into consideration were the following: the mean cost of materials for each type of examination and of medications used for each patient, personnel costs, machinery mortgages' costs, ambulance transportation's costs, and general hospital expenditures. DRGs and reimbursements have been calculated on the basis of clinical indications and modalities of procedures.During the evaluation period 268 patients have been studied. The procedures taken into consideration included: 135 coronary angiographies, 36 right and left catheterizations plus coronary angiography, 87 coronary angiographies plus percutaneous coronary intervention (PCI), 10 PCI. The total cost of diagnostic catheterization was Itl 1,226,000 (Euro 632) whereas that of each PCI (including stent implantation in 80% of cases) associated in 87 cases with coronary angiography was Itl 5,956,000 (Euro 3044). Patients with an acute coronary syndrome or heart failure were mostly studied during their first hospital stay; those with stable disease (stable angina, previous myocardial infarction, valvular heart disease or cardiomyopathy without heart failure) were studied during ordinary hospital admission or in the context of a day-hospital. DRGs and corresponding reimbursements for the different clinical situations were the following: unstable angina DRG 124 valued at Itl 6,180,000; stable angina DRG 125 valued at Itl 3,900,000; acute or recent myocardial infarction with or without complications DRG 121 or 122 valued at ItI 8,290,000 or Itl 5,900,000; heart failure in valvular heart disease or cardiomyopathy DRG 124 valued at Itl 6,180,000; valvular heart disease or cardiomyopathy DRG 125 valued at Itl 3,900,000. The DRG for a PCI is no. 112 valued at Itl 10,235,000.The costs of diagnostic and interventional hemodynamic procedures were acceptable and proportional to the DRG-related reimbursements. Appropriately indicated procedures and their quick execution during the first hospital stay lead to global economic savings for the health care system and are also clinically advantageous for the individual patient.

For studying the internal part of the array feeding structure the generalized admittance matrix (GAM) method seems to offer advantages in terms of effectiveness and accuracy, especially when the feeding structure, no matter how complex, can be partitioned into rectangular prisms. When applied to studying the interactions between elements of an array, the GAM algorithm has to be joined with a the method of moment (MoM) in the free space region, that uses the modes of a rectangular waveguide as basis functions. However, the analysis becomes computationally prohibitive both for dynamic memory and CPU time. In order to reduce the computational complexity, the effort should be substantially concentrated on the reduction of the number of unknowns. In this paper is presented a criteria to compress the solving matrix, which is based on synthetic aperture functions (SAP) expansion of the electric field on each array aperture.

___

An antenna array is designed for ion cyclotron resonance heating (ICRH) for the IGNITOR experiment, planned to operate in the 70–140 MHz frequency range. The design is based on the conventional strap antenna element, and in our proposed design each strap is fed by a RF power generator via a coaxial cable and a tuning and matching system. The coupling properties of the antenna are calculated with a slab model of the plasma. We consider first a two-dimensional problem to obtain the parameters of the transmission line model for the strap and feeder currents; the current profile thus obtained is then used in a three-dimensional simulation of the antenna that yields the radiation resistance; the input impedance of the straps is then obtained from the radiation resistance and the line parameters. Two methods to obtain the strap input impedance are compared. The first is based on a distributed concept of the radiated power, i.e. introducing a resistance per unit length equal to the ratio between the radiation re...

Wall losses in microwave cavities induce spatial phase variations in all held components. These variations depend on the component and can often be studied separately for each component by the use of suitable transmission line models. By a complete electromagnetic approach the phase relation between different components can be easily found, along with spatial variations, and it can be pointed out that in the presence of losses the vector field polarization is no longer linear, but becomes elliptic and point dependent. In this paper this new way of looking at the effects of wall losses in metal cavities is discussed, as it may become relevant in the context of the study of cavities for atomic frequency standards. In fact, circularly polarized fields can excite different atomic transitions than linearly polarized ones. Another detail which can be studied by electromagnetic calculations, as opposed to transmission line models, is the localized effect of the source on phase and polarization in the neighbourhood of the feed. Useful approaches to this more complex problem are outlined in this paper, and preliminary results are given for the case of a cylindrical TE/sub 011/ cavity, recommended for use in a cesium fountain frequency standard. >

A survey of 30,907 slaughterhouse cattle (5,984 calves, 15,937 young adult, 8,986 cows) was carried out to determine the incidence of blood and serous cysts on atrioventricular valves. The cysts were classified by their content (blood/serous fluid), location (mitral/tricuspid valve), and size. Cyst wall samples were processed for histology, immunohistochemistry for factor VIII-related antigen, and transmission electron microscopy. The content of some cysts was studied by electrophoresis and biochemical and microbiologic methods. Older cows had a higher incidence (16.2%) than younger animals (11.5% in calves, 7.9% in steers, 6.4% in heifers), suggesting that the lesions may be acquired. Blood cysts were often present on both atrioventricular valves; serous cysts prevailed on the mitral valve. Cysts of both types were larger in older animals; serous cysts were larger than the blood cysts. Histologically, blood cysts contained fresh blood, and serous cysts were filled with a hyaline fluid devoid of cells, sterile, and biochemically similar to lymph. All the cysts were lined with endothelium, but a positive immunostaining for the factor VIII-related antigen was appreciable only in blood cysts. Ultrastructurally, the endothelium was composed of flat endothelial cells holding several cytoplasmic filaments, lying in blood cysts on a continuous and often laminated basal lamina with many cytoplasmic projections. The results support the hypothesis that cysts of the atrioventricular valves derive from the dilation of blood and lymphatic valvular vessels, do not regress with age, and are mainly the result of mechanical effects.

Coppa di testa is a traditional cooked pork salami produced in different Italian regions. The main raw material is deboned meat of pork head with the addition of tongue and rind. After a long (3-5 h) high temperature (97°C) cooking, additives and flavourings are added and the salami is prepared. After cooling the salami is often portioned and vacuum- packaged. In this study the growth of naturally occurring contamination of Listeria innocua in three batches of vacuum packaged Coppa di testa, stored at 4°C for 80 days, is described. The average max was 0.24 (days-1) and the average doubling time was 2.87 days. The maximum growth level ranged from 4.90 to 8.17 (log10 cfu/g). These results indicate that Coppa di testa definitely supports the growth of Listeria innocua in the considered storage conditions. Taking into account that at 4°C Listeria monocytogenes strains are associated with higher grow rates than L. innocua, these results emphasize the importance of preventing Listeria monocytogenes contamination in the production stages following cooking.

The authors review the clinical, macro- and microscopical features, and pathogenesis of viral haemorrhagic disease (VHD) of rabbits and the European brown hare syndrome (EBHS). The two diseases share similar clinical and pathological manifestations involving an acute syndrome, sometimes accompanied by nervous and respiratory symptoms and epistaxis, and in all cases by severe hepatic damage and multifocal haemorrhages leading to fatal shock. The hepatic lesions (necrosis and inflammation) result from direct cytolytic and indirect microthrombotic effects of the causal agent. Endothelial lesions and a primary or secondary defect of coagulation factors are possible causes of the haemorrhagic syndrome. Typical lesions consist of necrotic hepatitis and congestion, haemorrhaging and oedema of the lungs and trachea. The histological and ultrastructural alterations of the liver are similar to those found in certain cases of acute fatal hepatitis in man. The high correlation between histologically typical hepatic findings and immunohistochemistry and immunoelectron microscopy is of diagnostic value. Both microscopic lesions and pathogenesis favour the unifying definition of "infectious necrotic hepatitis of Leporids" for the two disease entities.

Aperture coupling to enclosures with low interior losses can cause marked changes in the scattering characteristics of a target without perforation. The changes are attributable primarily to interior resonances. In a previous frequency domain study, a generally applicable self-consistent system format has been introduced for “observable-based” analytical modeling of the exterior-interior wave processes pertaining to cavity backed aperture geometries. The formulation has been applied there to plane-wave scattering from a slit-perforated thin perfectly conducting smooth convex, cylindrical shell with an interior perfectly conducting smooth convex cylindrical load, modeled externally via the ray fields of the geometrical theory of diffraction, internally via guided modes in the annular waveguide between the inner and outer boundaries, and coupled self-consistently by the slit. This study is extended here to short-pulse plane wave excitation. The various wave constituents are now distinguished by their different arrival and turn-on times. Alternative hybrid wavefront-resonance formulations are explored and are shown to furnish well convergent parametrizations of the physical observables in the scattered signal.

We present measurements of iso-frequency dispersion surfaces of light scattered from metallic micro-gratings with different periods. The dispersion surfaces, obtained using an infinity-corrected microscope objective, exhibit maxima attributed to diffracted orders as they become evanescent and pronounced minima due to the resonant excitation of surface plasmon polaritons (SPPs). We have also measured the enhanced photoluminescence of a thin layer of dye molecules on top of the grating. This enhanced luminescence is attributed to the local field enhancement close to the surface due to the coupling of the excitation frequency to SPPs. Moreover, we obtain a directional emission of the luminescence, which is attributed to the grating-assisted coupling of SPPs excited by the dye to free space light. The technique used for the measurements presented in this paper can be extended to characterize the angular emission patterns of emitters coupled to micro- and nano-plasmonic structures.

An InP/InGaAs-based photonic band-edge laser bonded on silicon operating near 1.55 mum is presented. A gold reflector positioned below the slab containing the active layer reduces the optical losses of the Bloch-mode resonator. As a result, a quality factor exceeding 8000 is obtained at transparency leading to a laser threshold as low as 3.4 muJ/cm 2

We report on the continuous-wave operation of a band edge laser at room temperature near 1.55 mum in an InGaAs/InP photonic crystal. A flat dispersion band-edge photonic mode is used for surface normal operation. The photonic crystal slab is integrated onto a Silicon chip by means of Au/In bonding technology, which combines two advantages, efficient heat sinking and broad band reflectivity.

We demonstrate experimentally all-optical bistable operation in an InP-based two-dimensional photonic crystal slab lying on top of a Bragg reflector. Bistability is obtained around 1550nm, using a low group velocity mode at the band edge of the photonic dispersion characteristic. The origin of the bistable regime is shown to be the fast (275ps relaxation time), electronically induced nonlinear refraction index. A low intensity threshold of 4kW∕cm2 was observed, with a contrast of 65% between the high and low reflectivity states.

We observed visible second-harmonic and ultraviolet third-harmonic fields generated in reflection from the surface of a two-dimensional triangular GaN/sapphire photonic crystal. When the pump radiation resonates with a photonic mode, enhancement factors as high as 250 and 3500 occurred for the second- and third-harmonic signals, respectively, as compared to the unpatterned GaN slab. The very large increase of third-harmonic field, with a photon energy exceeding that of the electronic band gap, was used as an efficient mechanism to induce GaN photoluminescence.

An InP-based two-dimensional photonic crystal slab laser is optimized in order to exhibit low group velocity modes both at the pumping and the lasing wavelength. Laser operation is demonstrated at 1566nm in the pulsed regime. A threshold of 4kW∕cm2 is demonstrated by pumping at the photonic mode lying in the bound quantum well electronic levels, one longitudinal optical phonon energy below the lasing photonic mode.

Summary After oral administration of CCI4 and CBrCI3, products of reaction of trichloromethyl free radical (CCI3) were identified by electron-capture gas chromatography. In rat livers 15 minutes after treatment with CCI4, the metabolites CHCI3 and C2CI6 were detected. CHCI3, CCI4, CHBrCI2 and C2CI6 were present 15 min after administration of CBrCI3: the possible formation of the radical CBrCI2 in addition to CCI3 by liver metabolism should also be taken into consideration.

Nonlinear reflection and diffraction measurements have been performed on a GaAs/AlGaAs photonic-crystal waveguide patterned with a square lattice: The basis in the two-dimensional unit cell consists of rings of air in the dielectric matrix. The measured angles of diffracted second-harmonic beams agree with those predicted for nonlinear diffraction conditions, Results for second-harmonic intensities as a function of incidence angle, polarization, and pump wavelength show that the reflected second-harmonic signal is dominated by the crystalline symmetry of GaAs, whereas nonlinear diffraction is determined by the photonic-crystal structure.

Second-harmonic generation (SHG) measurements in reflection on a ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{0.25}{\mathrm{Ga}}_{0.75}\mathrm{As}$ photonic crystal waveguide show a resonant enhancement when the pump beam is frequency and momentum matched with the photonic modes in the slab. The enhanced SH signal is observed in the form of resonant peaks, unlike in linear reflectance spectra. The observations are in very good agreement with a full 3D calculation of the anisotropic mode dispersion in the photonic crystal slab. The present results open the way towards realizing the extraordinary enhancement of SHG which was recently predicted [A. R. Cowan and J. F. Young, Phys. Rev. B $65,$ 085106 (2002)], and also demonstrate the potential of SHG as a nonlinear spectroscopic tool for optical studies of photonic crystals.

The distinctive features of true and false filling defects in the radio-opaque image of the upper urinary tract are discussed. The differential diagnosis of intrinsic intraluminal and parietal lacune is examined and several cases are presented by way of illustration.

The article reports on 1437 cases of narcosis for induced abortion conducted in the hospital of Niguarda, Italy, between June 1978-April 1979. As the majority of women treated were past the 10th week of pregnancy, general anesthesia was chosen, with little doses of thiapentol and NLA drugs; at the same time the patients were inhaling a mixture of O2 and N2O. This method proved far superior to other techniques experimented; there was perfect muscular relaxation, no obstetric or anesthesiological complications, no vomiting, and no necessity to help breathing at awakening. Most patients left the hospital the same day.

The first record in Italy of Micipsella numidica (Seurat, 1917) is reported. The parasite was collected from the portal vein of two rabbits (Oryctolagus cuniculus). Morphological features of the worms (4 females, 3 males and microfilariae from uterus) are described and compared with those reported for African, European and Asiatic specimens found in hares.

In order to further evaluate the role of intracranial pressure (ICP) monitoring in brain injured, comatose patients, in terms of both prognostic significance and usefulness for treatment, our total series of monitored patients has been reviewed.

A case of late postoperative cardiac tamponade causing selective compression of the left ventricle is presented. The patient had undergone aortic valve replacement and presented a picture of severe pulmonary venous congestion and low systemic output. The diagnosis was made on echocardiographic data and because of the failure to respond to inotropic and diuretic therapy. Surgical drainage resulted in a rapid improvement of the patient's hemodynamic functions.

We report a case of severe and rare complications of amphetamine abuse: intracerebral hemorrhage and spasm-induced changes in the cerebral vessels. The pathogenesis and treatment are discussed in the light of published data.

The problems associated with infections by dermatophytes and related fungi are discussed. Published and unpublished surveys of 1 481 wild animals of the orders Carnivora, Ungulata, Lagomorpha, Rodentia, Insectivora and Chiroptera and of 29 birds proved to be positive for fungi which were classified as potentially pathogenic zoophilic, potentially pathogenic geophilic and normally non-pathogenic geophilic. Trichophyton mentagrophytes var. mentagrophytes was isolated from 11% of rodents; the fungus was also isolated from Insectivora, the hare and the ibex. T. mentagrophytes var. erinacei was reported in the hedgehog. Microsporum canis was reported in rodents from anthropogenic areas. M. gypseum was reported in Ungulata, Lagomorpha and Rodentia; other geophilic fungi were found in all the orders investigated, with the exception of Chiroptera which proved to be constantly negative. The relationship between the presence of animals and the "animalization" of the environment, and the consequent presence of geophilic fungi is discussed. It is concluded that wild animals may play a role as carriers of dermatophytes and related fungi, may create environmental conditions favourable to their growth and may help to monitor the presence of a fungus in a given area.

Alphaxalone — alphadolone (Althesin) causes a marked reduction of intracranial pressure (ICP, cerebral blood flow and metabolism (1,2). Thiopentone has a similar effect and has been successfully used against severe intracranial hypertension (HICP) in man (3).

Copyright 2021 (year) Society of Photo‑Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this publication for a fee or for commercial purposes, and modification of the contents of the publication are prohibited. The BEaTriX (Beam Expander Testing X-ray) facility under construction at INAF-Brera Astronomical Observatory aims at performing the acceptance tests of the Silicon Pore Optics mirror modules of the ATHENA (Advanced Telescope for High-ENergy Astrophysics) X-ray observatory. The facility implements a grazing-incidence collimating mirror that, together with a monochromator and a beam expander stages based on crystals, enables the full X-ray illumination of the mirror modules under test. We present the development and test of the collimating mirror, a paraboloid sector having an optical surface of 400 mm -60 mm and sagittal radii of about 155 mm. The ground and lapped optics made of HOQ 310 fused quartz was corrected by bonnet polishing. In this paper, we report on the smoothing of mid-to-high spatial frequency error by pitch-tool polishing process, and on the correction of residual surface shape errors by ion-beam figuring process, both performed at INAF-Brera Astronomical Observatory. We present the X-ray test campaigns carried out on the mirror at PANTER facility, before and after coating it with a Pt layer via magnetron sputtering at DTU Space. The results provide an overview of the mirror performance in terms of angular resolution pre- and post-coating deposition.

The ACE project initiated the start of several integration activities between European institutions involved in electromagnetic modeling of antennas with planar or conformal topologies. The goal of the integration activities was / is not to create a global software package that integrates the software of all partners, but to initiate a long term process for antenna software integration activities within the European antenna community. During the first two years of ACE the integration activities were performed in several groups with a rather small number of partners in each group. The groups were formed by partners who wanted to integrate a specific approach developed by one partner into the software code of another partner. This allows increasing the capability and efficiency of a software code. In this paper a short overview of all integration activities is given.

In an InP-based two-dimensional photonic crystal slab laser effect is improved 10-fold by optically pumping at a low group velocity mode situated one longitudinal optical phonon energy below the lasing mode.