On the Simultaneous Conjugate Match of N-Port Networks

Some advancements are proposed to the theory of simultaneous conjugate match (SCM) of N -ports. It is shown that, if a network qualifies for geometrical unconditional stability (g-), then it can be matched simultaneously at all ports. The proof serves as the basis for constructing an iterative algorithm (AlgG) which is guaranteed to converge to the SCM condition for all N -ports exhibiting g-. In addition to the main results above mentioned, two more iterative algorithms are presented (AlgS and AlsA), which are conjectured to work for all networks satisfying g-. AlgS can be shown to converge globally for TEXPRESERVE3 and AlgA to converge locally for all N . Besides their theoretical interest, these results find a natural application in the matching of passive networks, and in particular of N -element phased arrays. However, they can be applied to any (i.e., also active) N -port as long as this is known to exhibit g-

Partitioned Ohtomo stability test for efficient analysis of large-signal solutions

A fundamental step in the design of electronic circuits is the verification that they are stable at least on a given set of external terminations, in order to avoid that the solution found be not observable in practice. This is especially true at microwave and millimeter-wave circuits, which are typically analyzed in the frequency domain rather than in the time domain. As a consequence, both in the linear and large-signal case, unstable solutions may be found instead of an observable one. Unfortunately, as compared to the linear case, the stability analysis of large-signal solutions is significantly more cumbersome. In particular, although it is possible to translate the small-signal tests based on the Nyquist principle to large-signal equivalents, the price to pay is a significant increase in matrix size. In the case of the Ohtomo test, which has only recently been applied to large-signal solutions, it is however possible to exploit the structure of the problem to significantly reduce the complexity and, therefore, simulation time. A real-world balanced amplifier is selected to validate the proposed method and illustrate its practical usage. The application of the method to a realistic monolithic circuit with a large number of devices is also presented

Pleomorphic Adenoma of the Parotid: Extracapsular Dissection Compared with Superficial Parotidectomy—A 10-Year Retrospective Cohort Study

The purpose of this study was to investigate the complication rates and effectiveness of extracapsular dissection compared with superficial parotidectomy for pleomorphic adenomas of the parotid gland from 2002 to 2012. The authors carried out a retrospective cohort study of 198 patients with pleomorphic adenomas of the parotid gland. Extracapsular dissection (ED) or superficial parotidectomy (SP) was performed. The recurrence rate and complications of the two surgical techniques were measured with a univariate analysis of each variable using the appropriate statistical analysis (chi-squared test or t-test). A total of 198 patients were enrolled between January 2003 and December 2012. The study included 97 females (48.99%) and 101 males (51.01%) whose mean age was 50.97 years (range 14–75). The type of surgery performed was ED in 153 patients (77.27%, 80 males and 73 females) and SP in 45 patients (22.73%, 21 males and 24 females). The mean follow-up time was 61.02 +/− 4.9 months for the patients treated with ED and 66.4 +/− 4.5 months for the patients treated with SP. Transient facial nerve injury and facial paralysis were significantly more frequent after SP than after ED (P=0.001 and P=0.065, resp.). No significant differences in capsular rupture, recurrence, and salivary fistula were observed after SP or ED: 2.2% versus 3.9%, 2.2% versus 3.3%, and 2.2% versus 0.65%, respectively. Extracapsular dissection may be considered the treatment of choice for pleomorphic adenomas located in the superficial portion of the parotid gland because this technique showed similar effectiveness and fewer side effects than superficial parotidectomy

Myoepithelioma of the parotid gland: A case report with review of the literature

Myoepithelioma is a rare tumor of the salivary glands belonging to a distinct category of neoplasms according to World Health Organization. It represents about 1% of all tumors that develop in the salivary glands. Generally the majority of myoepitheliomas are benign but malignant transformation can take place in untreated or recurrent cases. We present a case of a rare myoepithelioma of the left parotid gland, with review of literature. Keywords: Parotid gland, Salivary glands myoepithelioma, Benign salivary glands tumors, Myoepithelioma, Spindle cells myoepitheliom

Dust Masses, PAH Abundances, and Starlight Intensities in the SINGS Galaxy Sample

Physical dust models are presented for 65 galaxies in SINGS that are strongly detected in the four IRAC bands and three MIPS bands. For each galaxy we estimate (1) the total dust mass, (2) the fraction of the dust mass contributed by PAHs, and (3) the intensity of the starlight heating the dust grains. We find that spiral galaxies have dust properties resembling the dust in the local region of the Milky Way, with similar dust-to-gas ratio and similar PAH abundance. The observed SEDs, including galaxies with SCUBA photometry, can be reproduced by dust models that do not require "cold" (T ≾ 10 K) dust. The dust-to-gas ratio is observed to be dependent on metallicity. In the interstellar media of galaxies with A_O ≡ 12 + log_(10)(O/H) > 8.1, grains contain a substantial fraction of interstellar Mg, Si, and Fe. Galaxies with A_O 8.1 have a median q_(PAH) = 3.55%. The derived dust masses favor a value X_(CO) ≈ 4 × 10^(20) cm^(-2) (K km s^(-1))^(-1) for the CO-to-H_2 conversion factor. Except for some starbursting systems (Mrk 33, Tol 89, NGC 3049), dust in the diffuse ISM dominates the IR power

The Comet Interceptor Mission

Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA’s F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ΔV capability of 600 ms−1. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes – B1, provided by the Japanese space agency, JAXA, and B2 – that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission’s science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule

Characterization and modelling of high-frequency active devices oriented to high-sensitivity subsystem design

In this chapter, quite a broad overview of noise characterization-related topics is offered to the reader, with different depth levels. Most of the attention, however, is paid to the practical side of noise measurements and the subsequent steps of noise extraction and modeling, as well as to some advanced design methodologies. A major concern is in the procedures that are necessary to effectively de-embed the measurements from the contribution of the test bench and the adopted methodologies. The scope of the discussion cover a well-assessed theory concerning linear devices operated in the frequency range from a few megahertz to some 100 GHz, and at physical temperatures above some tens of kelvins. In these conditions, 1/f noise can be neglected and Johnson (thermal) noise is approximately independent of frequency; as a consequence, thermal and, possibly, shot noise of elemental noise sources add up to yield a white power spectrum, which can be conveniently described in terms of “equivalent” thermal noise. The second part of the chapter is devoted to the application of the device noise models in the proper design of single- and multistage low noise amplifiers, including a mixed technique that actually employs characterization techniques directly in the amplifier design

High spectral purity X- to W-band active GaAs monolithic frequency multiplier

In this contribution, an active high harmonic suppression x8 frequency multiplier using depletion-mode mHEMT devices and its design procedure are presented. The realized circuit exhibits 3 dB conversion gain in the 86.4 ÷ 91.2 GHz output frequency range, with 6 dBm output power. An harmonic suppression higher than 32 dBc has been achieved. The whole chip current consumption is 125 mA, occupying an area of 2.05 × 3.45 mm2. © 2014 IEEE

Automated Extraction of Device Noise Parameters Based on Multi-Frequency, Source- Pull Data

In this paper a novel approach for determining the four noise parameters of FET devices over frequency is presented. Such methodology is made of two parts: the first one allows to straightforwardly extract single-frequency noise parameters from source-pull data; the second one extends this capability to multi-frequency, source-pull data to obtain a full description of device noise behavior over frequency by means of at most 10 constant parameters (depending on the required accuracy). The whole process is automated via a software routine and does not need a previous knowledge of the FET equivalent circuit's topology, or the values of its elements. This peculiarity makes the proposed method very well suited to quick characterization campaigns of active devices, avoiding the burden of a whole set of prior, different measurements and the relevant, critical extraction procedures, which are strongly dependent on the device